[Title 40 CFR ]
[Code of Federal Regulations (annual edition) - July 1, 2021 Edition]
[From the U.S. Government Publishing Office]



[[Page i]]

          

                                       Title 40

                                Protection of Environment


                                ________________________

                                     Parts 50 to 51

                         Revised as of July 1, 2021

          Containing a codification of documents of general 
          applicability and future effect

          As of July 1, 2021
                    Published by the Office of the Federal Register 
                    National Archives and Records Administration as a 
                    Special Edition of the Federal Register

[[Page ii]]

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                            Table of Contents



                                                                    Page
  Explanation.................................................       v

  Title 40:
          Chapter I--Environmental Protection Agency 
          (Continued)                                                3
  Finding Aids:
      Table of CFR Titles and Chapters........................     685
      Alphabetical List of Agencies Appearing in the CFR......     705
      List of CFR Sections Affected...........................     715

[[Page iv]]





                     ----------------------------

                     Cite this Code: CFR
                     To cite the regulations in 
                       this volume use title, 
                       part and section number. 
                       Thus, 40 CFR 50.1 refers 
                       to title 40, part 50, 
                       section 1.

                     ----------------------------

[[Page v]]



                               EXPLANATION

    The Code of Federal Regulations is a codification of the general and 
permanent rules published in the Federal Register by the Executive 
departments and agencies of the Federal Government. The Code is divided 
into 50 titles which represent broad areas subject to Federal 
regulation. Each title is divided into chapters which usually bear the 
name of the issuing agency. Each chapter is further subdivided into 
parts covering specific regulatory areas.
    Each volume of the Code is revised at least once each calendar year 
and issued on a quarterly basis approximately as follows:

Title 1 through Title 16.................................as of January 1
Title 17 through Title 27..................................as of April 1
Title 28 through Title 41...................................as of July 1
Title 42 through Title 50................................as of October 1

    The appropriate revision date is printed on the cover of each 
volume.

LEGAL STATUS

    The contents of the Federal Register are required to be judicially 
noticed (44 U.S.C. 1507). The Code of Federal Regulations is prima facie 
evidence of the text of the original documents (44 U.S.C. 1510).

HOW TO USE THE CODE OF FEDERAL REGULATIONS

    The Code of Federal Regulations is kept up to date by the individual 
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    To determine whether a Code volume has been amended since its 
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EFFECTIVE AND EXPIRATION DATES

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OMB CONTROL NUMBERS

    The Paperwork Reduction Act of 1980 (Pub. L. 96-511) requires 
Federal agencies to display an OMB control number with their information 
collection request.

[[Page vi]]

Many agencies have begun publishing numerous OMB control numbers as 
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PAST PROVISIONS OF THE CODE

    Provisions of the Code that are no longer in force and effect as of 
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``[RESERVED]'' TERMINOLOGY

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INCORPORATION BY REFERENCE

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    An index to the text of ``Title 3--The President'' is carried within 
that volume.

[[Page vii]]

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    Oliver A. Potts,
    Director,
    Office of the Federal Register
    July 1, 2021







[[Page ix]]



                               THIS TITLE

    Title 40--Protection of Environment is composed of thirty-seven 
volumes. The parts in these volumes are arranged in the following order: 
Parts 1-49, parts 50-51, part 52 (52.01-52.1018), part 52 (52.1019-
52.2019), part 52 (52.2020-end of part 52), parts 53-59, part 60 (60.1-
60.499), part 60 (60.500-end of part 60, sections), part 60 
(Appendices), parts 61-62, part 63 (63.1-63.599), part 63 (63.600-
63.1199), part 63 (63.1200-63.1439), part 63 (63.1440-63.6175), part 63 
(63.6580-63.8830), part 63 (63.8980-end of part 63), parts 64-71, parts 
72-79, part 80, part 81, parts 82-86, parts 87-95, parts 96-99, parts 
100-135, parts 136-149, parts 150-189, parts 190-259, parts 260-265, 
parts 266-299, parts 300-399, parts 400-424, parts 425-699, parts 700-
722, parts 723-789, parts 790-999, parts 1000-1059, and part 1060 to 
end. The contents of these volumes represent all current regulations 
codified under this title of the CFR as of July 1, 2021.

    Chapter I--Environmental Protection Agency appears in all thirty-
seven volumes. OMB control numbers for title 40 appear in Sec.  9.1 of 
this chapter.

    Chapters IV-IX--Regulations issued by the Environmental Protection 
Agency and Department of Justice, Council on Environmental Quality, 
Chemical Safety and Hazard Investigation Board, Environmental Protection 
Agency and Department of Defense; Uniform National Discharge Standards 
for Vessels of the Armed Forces, Gulf Coast Ecosystem Restoration 
Council, and the Federal Permitting Improvement Steering Council appear 
in volume thirty seven.

    For this volume, Michele Bugenhagen was Chief Editor. The Code of 
Federal Regulations publication program is under the direction of John 
Hyrum Martinez, assisted by Stephen J. Frattini.

[[Page 1]]



                   TITLE 40--PROTECTION OF ENVIRONMENT




                   (This book contains parts 50 to 51)

  --------------------------------------------------------------------
                                                                    Part

chapter i--Environmental Protection Agency (Continued)......          50

[[Page 3]]



         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)




  --------------------------------------------------------------------

                       SUBCHAPTER C--AIR PROGRAMS
Part                                                                Page
50              National primary and secondary ambient air 
                    quality standards.......................           5
51              Requirements for preparation, adoption, and 
                    submittal of implementation plans.......         169

[[Page 5]]



                        SUBCHAPTER C_AIR PROGRAMS





PART 50_NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS--
Table of Contents



Sec.
50.1 Definitions.
50.2 Scope.
50.3 Reference conditions.
50.4 National primary ambient air quality standards for sulfur oxides 
          (sulfur dioxide).
50.5 National secondary ambient air quality standard for sulfur oxides 
          (sulfur dioxide).
50.6 National primary and secondary ambient air quality standards for 
          PM10.
50.7 National primary and secondary ambient air quality standards for 
          PM2.5.
50.8 National primary ambient air quality standards for carbon monoxide.
50.9 National 1-hour primary and secondary ambient air quality standards 
          for ozone.
50.10 National 8-hour primary and secondary ambient air quality 
          standards for ozone.
50.11 National primary and secondary ambient air quality standards for 
          oxides of nitrogen (with nitrogen dioxide as the indicator).
50.12 National primary and secondary ambient air quality standards for 
          lead.
50.13 National primary and secondary ambient air quality standards for 
          PM2.5.
50.14 Treatment of air quality monitoring data influenced by exceptional 
          events.
50.15 National primary and secondary ambient air quality standards for 
          ozone.
50.16 National primary and secondary ambient air quality standards for 
          lead.
50.17 National primary ambient air quality standards for sulfur oxides 
          (sulfur dioxide).
50.18 National primary ambient air quality standards for 
          PM2.5.
50.19 National primary and secondary ambient air quality standards for 
          ozone.

Appendix A-1 to Part 50--Reference Measurement Principle and Calibration 
          Procedure for the Measurement of Sulfur Dioxide in the 
          Atmosphere (Ultraviolet Fluorescence Method)
Appendix A-2 to Part 50--Reference Method for the Determination of 
          Sulfur Dioxide in the Atmosphere (Pararosaniline Method)
Appendix B to Part 50--Reference Method for the Determination of 
          Suspended Particulate Matter in the Atmosphere (High-Volume 
          Method)
Appendix C to Part 50--Measurement Principle and Calibration Procedure 
          for the Measurement of Carbon Monoxide in the Atmosphere (Non-
          Dispersive Infrared Photometry)
Appendix D to Part 50--Reference Measurement Principle and Calibration 
          Procedure for the Measurement of Ozone in the Atmosphere 
          (Chemiluminescence Method)
Appendix E to Part 50 [Reserved]
Appendix F to Part 50--Measurement Principle and Calibration Procedure 
          for the Measurement of Nitrogen Dioxide in the Atmosphere (Gas 
          Phase Chemiluminescence)
Appendix G to Part 50--Reference Method for the Determination of Lead in 
          Total Suspended Particulate Matter
Appendix H to Part 50--Interpretation of the 1-Hour Primary and 
          Secondary National Ambient Air Quality Standards for Ozone
Appendix I to Part 50--Interpretation of the 8-Hour Primary and 
          Secondary National Ambient Air Quality Standards for Ozone
Appendix J to Part 50--Reference Method for the Determination of 
          Particulate Matter as PM10 in the Atmosphere
Appendix K to Part 50--Interpretation of the National Ambient Air 
          Quality Standards for Particulate Matter
Appendix L to Part 50--Reference Method for the Determination of Fine 
          Particulate Matter as PM2.5 in the Atmosphere
Appendix M to Part 50 [Reserved]
Appendix N to Part 50--Interpretation of the National Ambient Air 
          Quality Standards for PM2.5
Appendix O to Part 50--Reference Method for the Determination of Coarse 
          Particulate Matter as PM10-2.5 in the Atmosphere
Appendix P to Part 50--Interpretation of the Primary and Secondary 
          National Ambient Air Quality Standards for Ozone
Appendix Q to Part 50--Reference Method for the Determination of Lead in 
          Particulate Matter as PM10 Collected From Ambient 
          Air
Appendix R to Part 50--Interpretation of the National Ambient Air 
          Quality Standards for Lead
Appendix S to Part 50--Interpretation of the Primary National Ambient 
          Air Quality Standards for Oxides of Nitrogen (Nitrogen 
          Dioxide)
Appendix T to Part 50--Interpretation of the Primary National Ambient 
          Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide)
Appendix U to Part 50--Interpretation of the Primary and Secondary 
          National

[[Page 6]]

          Ambient Air Quality Standards for Ozone

    Authority: 42 U.S.C. 7401, et seq.

    Source: 36 FR 22384, Nov. 25, 1971, unless otherwise noted.



Sec. 50.1  Definitions.

    (a) As used in this part, all terms not defined herein shall have 
the meaning given them by the Act.
    (b) Act means the Clean Air Act, as amended (42 U.S.C. 1857-18571, 
as amended by Pub. L. 91-604).
    (c) Agency means the Environmental Protection Agency.
    (d) Administrator means the Administrator of the Environmental 
Protection Agency.
    (e) Ambient air means that portion of the atmosphere, external to 
buildings, to which the general public has access.
    (f) Reference method means a method of sampling and analyzing the 
ambient air for an air pollutant that is specified as a reference method 
in an appendix to this part, or a method that has been designated as a 
reference method in accordance with part 53 of this chapter; it does not 
include a method for which a reference method designation has been 
cancelled in accordance with Sec. 53.11 or Sec. 53.16 of this chapter.
    (g) Equivalent method means a method of sampling and analyzing the 
ambient air for an air pollutant that has been designated as an 
equivalent method in accordance with part 53 of this chapter; it does 
not include a method for which an equivalent method designation has been 
cancelled in accordance with Sec. 53.11 or Sec. 53.16 of this chapter.
    (h) Traceable means that a local standard has been compared and 
certified either directly or via not more than one intermediate 
standard, to a primary standard such as a National Bureau of Standards 
Standard Reference Material (NBS SRM), or a USEPA/NBS-approved Certified 
Reference Material (CRM).
    (i) Indian country is as defined in 18 U.S.C. 1151.
    (j) Exceptional event means an event(s) and its resulting emissions 
that affect air quality in such a way that there exists a clear causal 
relationship between the specific event(s) and the monitored 
exceedance(s) or violation(s), is not reasonably controllable or 
preventable, is an event(s) caused by human activity that is unlikely to 
recur at a particular location or a natural event(s), and is determined 
by the Administrator in accordance with 40 CFR 50.14 to be an 
exceptional event. It does not include air pollution relating to source 
noncompliance. Stagnation of air masses and meteorological inversions do 
not directly cause pollutant emissions and are not exceptional events. 
Meteorological events involving high temperatures or lack of 
precipitation (i.e., severe, extreme or exceptional drought) also do not 
directly cause pollutant emissions and are not considered exceptional 
events. However, conditions involving high temperatures or lack of 
precipitation may promote occurrences of particular types of exceptional 
events, such as wildfires or high wind events, which do directly cause 
emissions.
    (k) Natural event means an event and its resulting emissions, which 
may recur at the same location, in which human activity plays little or 
no direct causal role. For purposes of the definition of a natural 
event, anthropogenic sources that are reasonably controlled shall be 
considered to not play a direct role in causing emissions.
    (l) Exceedance with respect to a national ambient air quality 
standard means one occurrence of a measured or modeled concentration 
that exceeds the specified concentration level of such standard for the 
averaging period specified by the standard.
    (m) Prescribed fire is any fire intentionally ignited by management 
actions in accordance with applicable laws, policies, and regulations to 
meet specific land or resource management objectives.
    (n) Wildfire is any fire started by an unplanned ignition caused by 
lightning; volcanoes; other acts of nature; unauthorized activity; or 
accidental, human-caused actions, or a prescribed fire that has 
developed into a wildfire. A wildfire that predominantly occurs on 
wildland is a natural event.
    (o) Wildland means an area in which human activity and development 
are essentially non-existent, except for roads, railroads, power lines, 
and similar transportation facilities. Structures, if any, are widely 
scattered.

[[Page 7]]

    (p) High wind dust event is an event that includes the high-speed 
wind and the dust that the wind entrains and transports to a monitoring 
site.
    (q) High wind threshold is the minimum wind speed capable of causing 
particulate matter emissions from natural undisturbed lands in the area 
affected by a high wind dust event.
    (r) Federal land manager means, consistent with the definition in 40 
CFR 51.301, the Secretary of the department with authority over the 
Federal Class I area (or the Secretary's designee) or, with respect to 
Roosevelt-Campobello International Park, the Chairman of the Roosevelt-
Campobello International Park Commission.

[36 FR 22384, Nov. 25, 1971, as amended at 41 FR 11253, Mar. 17, 1976; 
48 FR 2529, Jan. 20, 1983; 63 FR 7274, Feb. 12, 1998; 72 FR 13580, Mar. 
22, 2007; 81 FR 68276, Oct. 3, 2016]



Sec. 50.2  Scope.

    (a) National primary and secondary ambient air quality standards 
under section 109 of the Act are set forth in this part.
    (b) National primary ambient air quality standards define levels of 
air quality which the Administrator judges are necessary, with an 
adequate margin of safety, to protect the public health. National 
secondary ambient air quality standards define levels of air quality 
which the Administrator judges necessary to protect the public welfare 
from any known or anticipated adverse effects of a pollutant. Such 
standards are subject to revision, and additional primary and secondary 
standards may be promulgated as the Administrator deems necessary to 
protect the public health and welfare.
    (c) The promulgation of national primary and secondary ambient air 
quality standards shall not be considered in any manner to allow 
significant deterioration of existing air quality in any portion of any 
State or Indian country.
    (d) The proposal, promulgation, or revision of national primary and 
secondary ambient air quality standards shall not prohibit any State or 
Indian country from establishing ambient air quality standards for that 
State or area under a tribal CAA program or any portion thereof which 
are more stringent than the national standards.

[36 FR 22384, Nov. 25, 1971, as amended at 63 FR 7274, Feb. 12, 1998]



Sec. 50.3  Reference conditions.

    All measurements of air quality that are expressed as mass per unit 
volume (e.g., micrograms per cubic meter) other than for particulate 
matter (PM2.5) standards contained in Sec. Sec. 50.7, 50.13, 
and 50.18, and lead standards contained in Sec. 50.16 shall be 
corrected to a reference temperature of 25 (deg) C and a reference 
pressure of 760 millimeters of mercury (1,013.2 millibars). Measurements 
of PM2.5 for purposes of comparison to the standards 
contained in Sec. Sec. 50.7, 50.13, and 50.18, and of lead for purposes 
of comparison to the standards contained in Sec. 50.16 shall be 
reported based on actual ambient air volume measured at the actual 
ambient temperature and pressure at the monitoring site during the 
measurement period.

[78 FR 3277, Jan. 15, 2013]



Sec. 50.4  National primary ambient air quality standards for sulfur oxides (sulfur dioxide).

    (a) The level of the annual standard is 0.030 parts per million 
(ppm), not to be exceeded in a calendar year. The annual arithmetic mean 
shall be rounded to three decimal places (fractional parts equal to or 
greater than 0.0005 ppm shall be rounded up).
    (b) The level of the 24-hour standard is 0.14 parts per million 
(ppm), not to be exceeded more than once per calendar year. The 24-hour 
averages shall be determined from successive nonoverlapping 24-hour 
blocks starting at midnight each calendar day and shall be rounded to 
two decimal places (fractional parts equal to or greater than 0.005 ppm 
shall be rounded up).
    (c) Sulfur oxides shall be measured in the ambient air as sulfur 
dioxide by the reference method described in appendix A to this part or 
by an equivalent method designated in accordance with part 53 of this 
chapter.
    (d) To demonstrate attainment, the annual arithmetic mean and the 
second-highest 24-hour averages must be based upon hourly data that are 
at

[[Page 8]]

least 75 percent complete in each calendar quarter. A 24-hour block 
average shall be considered valid if at least 75 percent of the hourly 
averages for the 24-hour period are available. In the event that only 
18, 19, 20, 21, 22, or 23 hourly averages are available, the 24-hour 
block average shall be computed as the sum of the available hourly 
averages using 18, 19, etc. as the divisor. If fewer than 18 hourly 
averages are available, but the 24-hour average would exceed the level 
of the standard when zeros are substituted for the missing values, 
subject to the rounding rule of paragraph (b) of this section, then this 
shall be considered a valid 24-hour average. In this case, the 24-hour 
block average shall be computed as the sum of the available hourly 
averages divided by 24.
    (e) The standards set forth in this section will remain applicable 
to all areas notwithstanding the promulgation of SO2 national 
ambient air quality standards (NAAQS) in Sec. 50.17. The SO2 
NAAQS set forth in this section will no longer apply to an area one year 
after the effective date of the designation of that area, pursuant to 
section 107 of the Clean Air Act, for the SO2 NAAQS set forth 
in Sec. 50.17; except that for areas designated nonattainment for the 
SO2 NAAQS set forth in this section as of the effective date 
of Sec. 50.17, and areas not meeting the requirements of a SIP call 
with respect to requirements for the SO2 NAAQS set forth in 
this section, the SO2 NAAQS set forth in this section will 
apply until that area submits, pursuant to section 191 of the Clean Air 
Act, and EPA approves, an implementation plan providing for attainment 
of the SO2 NAAQS set forth in Sec. 50.17.

[61 FR 25579, May 22, 1996, as amended at 75 FR 35592, June 22, 2010]



Sec. 50.5  National secondary ambient air quality standard for sulfur
oxides (sulfur dioxide).

    (a) The level of the 3-hour standard is 0.5 parts per million (ppm), 
not to be exceeded more than once per calendar year. The 3-hour averages 
shall be determined from successive nonoverlapping 3-hour blocks 
starting at midnight each calendar day and shall be rounded to 1 decimal 
place (fractional parts equal to or greater than 0.05 ppm shall be 
rounded up).
    (b) Sulfur oxides shall be measured in the ambient air as sulfur 
dioxide by the reference method described in appendix A of this part or 
by an equivalent method designated in accordance with part 53 of this 
chapter.
    (c) To demonstrate attainment, the second-highest 3-hour average 
must be based upon hourly data that are at least 75 percent complete in 
each calendar quarter. A 3-hour block average shall be considered valid 
only if all three hourly averages for the 3-hour period are available. 
If only one or two hourly averages are available, but the 3-hour average 
would exceed the level of the standard when zeros are substituted for 
the missing values, subject to the rounding rule of paragraph (a) of 
this section, then this shall be considered a valid 3-hour average. In 
all cases, the 3-hour block average shall be computed as the sum of the 
hourly averages divided by 3.

[61 FR 25580, May 22, 1996]



Sec. 50.6  National primary and secondary ambient air quality 
standards for PM10.

    (a) The level of the national primary and secondary 24-hour ambient 
air quality standards for particulate matter is 150 micrograms per cubic 
meter ([micro]g/m\3\), 24-hour average concentration. The standards are 
attained when the expected number of days per calendar year with a 24-
hour average concentration above 150 [micro]g/m\3\, as determined in 
accordance with appendix K to this part, is equal to or less than one.
    (b) [Reserved]
    (c) For the purpose of determining attainment of the primary and 
secondary standards, particulate matter shall be measured in the ambient 
air as PM10 (particles with an aerodynamic diameter less than 
or equal to a nominal 10 micrometers) by:
    (1) A reference method based on appendix J and designated in 
accordance with part 53 of this chapter, or
    (2) An equivalent method designated in accordance with part 53 of 
this chapter.

[52 FR 24663, July 1, 1987, as amended at 62 FR 38711, July 18, 1997; 65 
FR 80779, Dec. 22, 2000; 71 FR 61224, Oct. 17, 2006]

[[Page 9]]



Sec. 50.7  National primary and secondary ambient air quality
standards for PM2.5.

    (a) The national primary and secondary ambient air quality standards 
for particulate matter are 15.0 micrograms per cubic meter ([micro]g/
m\3\) annual arithmetic mean concentration, and 65 [micro]g/m\3\ 24-hour 
average concentration measured in the ambient air as PM2.5 
(particles with an aerodynamic diameter less than or equal to a nominal 
2.5 micrometers) by either:
    (1) A reference method based on appendix L of this part and 
designated in accordance with part 53 of this chapter; or
    (2) An equivalent method designated in accordance with part 53 of 
this chapter.
    (b) The annual primary and secondary PM2.5 standards are 
met when the annual arithmetic mean concentration, as determined in 
accordance with appendix N of this part, is less than or equal to 15.0 
micrograms per cubic meter.
    (c) The 24-hour primary and secondary PM2.5 standards are 
met when the 98\th\ percentile 24-hour concentration, as determined in 
accordance with appendix N of this part, is less than or equal to 65 
micrograms per cubic meter.

[62 FR 38711, July 18, 1997, as amended at 69 FR 45595, July 30, 2004]



Sec. 50.8  National primary ambient air quality standards for carbon
monoxide.

    (a) The national primary ambient air quality standards for carbon 
monoxide are:
    (1) 9 parts per million (10 milligrams per cubic meter) for an 8-
hour average concentration not to be exceeded more than once per year 
and
    (2) 35 parts per million (40 milligrams per cubic meter) for a 1-
hour average concentration not to be exceeded more than once per year.
    (b) The levels of carbon monoxide in the ambient air shall be 
measured by:
    (1) A reference method based on appendix C and designated in 
accordance with part 53 of this chapter, or
    (2) An equivalent method designated in accordance with part 53 of 
this chapter.
    (c) An 8-hour average shall be considered valid if at least 75 
percent of the hourly average for the 8-hour period are available. In 
the event that only six (or seven) hourly averages are available, the 8-
hour average shall be computed on the basis of the hours available using 
six (or seven) as the divisor.
    (d) When summarizing data for comparision with the standards, 
averages shall be stated to one decimal place. Comparison of the data 
with the levels of the standards in parts per million shall be made in 
terms of integers with fractional parts of 0.5 or greater rounding up.

[50 FR 37501, Sept. 13, 1985]



Sec. 50.9  National 1-hour primary and secondary ambient air quality
standards for ozone.

    (a) The level of the national 1-hour primary and secondary ambient 
air quality standards for ozone measured by a reference method based on 
appendix D to this part and designated in accordance with part 53 of 
this chapter, is 0.12 parts per million (235 [micro]g/m\3\). The 
standard is attained when the expected number of days per calendar year 
with maximum hourly average concentrations above 0.12 parts per million 
(235 [micro]g/m\3\) is equal to or less than 1, as determined by 
appendix H to this part.
    (b) The 1-hour standards set forth in this section will remain 
applicable to all areas notwithstanding the promulgation of 8-hour ozone 
standards under Sec. 50.10. The 1-hour NAAQS set forth in paragraph (a) 
of this section will no longer apply to an area one year after the 
effective date of the designation of that area for the 8-hour ozone 
NAAQS pursuant to section 107 of the Clean Air Act. Area designations 
and classifications with respect to the 1-hour standards are codified in 
40 CFR part 81.

[62 FR 38894, July 18, 1997, as amended at 65 FR 45200, July 20, 2000; 
68 FR 38163, June 26, 2003, 69 FR 23996, Apr. 30, 2004; 77 FR 28441, May 
14, 2012]



Sec. 50.10  National 8-hour primary and secondary ambient air quality
standards for ozone.

    (a) The level of the national 8-hour primary and secondary ambient 
air quality standards for ozone, measured

[[Page 10]]

by a reference method based on appendix D to this part and designated in 
accordance with part 53 of this chapter, is 0.08 parts per million 
(ppm), daily maximum 8-hour average.
    (b) The 8-hour primary and secondary ozone ambient air quality 
standards are met at an ambient air quality monitoring site when the 
average of the annual fourth-highest daily maximum 8-hour average ozone 
concentration is less than or equal to 0.08 ppm, as determined in 
accordance with appendix I to this part.
    (c) Until the effective date of the final Implementation of the 2008 
National Ambient Air Quality Standards for Ozone: State Implementation 
Plan Requirements Rule (final SIP Requirements Rule) to be codified at 
40 CFR 51.1100 et seq., the 1997 ozone NAAQS set forth in this section 
will continue in effect, notwithstanding the promulgation of the 2008 
ozone NAAQS under Sec. 50.15. The 1997 ozone NAAQS set forth in this 
section will no longer apply upon the effective date of the final SIP 
Requirements Rule. For purposes of the anti-backsliding requirements of 
Sec. 51.1105, Sec. 51.165 and Appendix S to part 51, the area 
designations and classifications with respect to the revoked 1997 ozone 
NAAQS are codified in 40 CFR part 81.

[62 FR 38894, July 18, 1997, as amended at 77 FR 30170, May 21, 2012; 80 
FR 12312, Mar. 6, 2015]



Sec. 50.11  National primary and secondary ambient air quality 
standards for oxides of nitrogen (with nitrogen dioxide as the
indicator).

    (a) The level of the national primary annual ambient air quality 
standard for oxides of nitrogen is 53 parts per billion (ppb, which is 1 
part in 1,000,000,000), annual average concentration, measured in the 
ambient air as nitrogen dioxide.
    (b) The level of the national primary 1-hour ambient air quality 
standard for oxides of nitrogen is 100 ppb, 1-hour average 
concentration, measured in the ambient air as nitrogen dioxide.
    (c) The level of the national secondary ambient air quality standard 
for nitrogen dioxide is 0.053 parts per million (100 micrograms per 
cubic meter), annual arithmetic mean concentration.
    (d) The levels of the standards shall be measured by:
    (1) A reference method based on appendix F to this part; or
    (2) By a Federal equivalent method (FEM) designated in accordance 
with part 53 of this chapter.
    (e) The annual primary standard is met when the annual average 
concentration in a calendar year is less than or equal to 53 ppb, as 
determined in accordance with appendix S of this part for the annual 
standard.
    (f) The 1-hour primary standard is met when the three-year average 
of the annual 98th percentile of the daily maximum 1-hour average 
concentration is less than or equal to 100 ppb, as determined in 
accordance with appendix S of this part for the 1-hour standard.
    (g) The secondary standard is attained when the annual arithmetic 
mean concentration in a calendar year is less than or equal to 0.053 
ppm, rounded to three decimal places (fractional parts equal to or 
greater than 0.0005 ppm must be rounded up). To demonstrate attainment, 
an annual mean must be based upon hourly data that are at least 75 
percent complete or upon data derived from manual methods that are at 
least 75 percent complete for the scheduled sampling days in each 
calendar quarter.

[75 FR 6531, Feb. 9, 2010]



Sec. 50.12  National primary and secondary ambient air quality 
standards for lead.

    (a) National primary and secondary ambient air quality standards for 
lead and its compounds, measured as elemental lead by a reference method 
based on appendix G to this part, or by an equivalent method, are: 1.5 
micrograms per cubic meter, maximum arithmetic mean averaged over a 
calendar quarter.
    (b) The standards set forth in this section will remain applicable 
to all areas notwithstanding the promulgation of lead national ambient 
air quality standards (NAAQS) in Sec. 50.16. The lead NAAQS set forth 
in this section will no longer apply to an area one

[[Page 11]]

year after the effective date of the designation of that area, pursuant 
to section 107 of the Clean Air Act, for the lead NAAQS set forth in 
Sec. 50.16; except that for areas designated nonattainment for the lead 
NAAQS set forth in this section as of the effective date of Sec. 50.16, 
the lead NAAQS set forth in this section will apply until that area 
submits, pursuant to section 191 of the Clean Air Act, and EPA approves, 
an implementation plan providing for attainment and/or maintenance of 
the lead NAAQS set forth in Sec. 50.16.

(Secs. 109, 301(a) Clean Air Act as amended (42 U.S.C. 7409, 7601(a)))

[43 FR 46258, Oct. 5, 1978, as amended at 73 FR 67051, Nov. 12, 2008]



Sec. 50.13  National primary and secondary ambient air quality
standards for PM2.5.

    (a) The national primary and secondary ambient air quality standards 
for particulate matter are 15.0 micrograms per cubic meter ([micro]g/
m\3\) annual arithmetic mean concentration, and 35 [micro]g/m\3\ 24-hour 
average concentration measured in the ambient air as PM2.5 
(particles with an aerodynamic diameter less than or equal to a nominal 
2.5 micrometers) by either:
    (1) A reference method based on appendix L of this part and 
designated in accordance with part 53 of this chapter; or
    (2) An equivalent method designated in accordance with part 53 of 
this chapter.
    (b) The annual primary and secondary PM2.5 standards are 
met when the annual arithmetic mean concentration, as determined in 
accordance with appendix N of this part, is less than or equal to 15.0 
[micro]g/m\3\.
    (c) The 24-hour primary and secondary PM2.5 standards are 
met when the 98th percentile 24-hour concentration, as determined in 
accordance with appendix N of this part, is less than or equal to 35 
[micro]g/m\3\.
    (d) Until the effective date of the final Fine Particulate Matter 
National Ambient Air Quality Standards: State Implementation Plan 
Requirements rule to be codified at 40 CFR 51.1000 through 51.1016, the 
1997 annual PM2.5 NAAQS set forth in this section will 
continue in effect, notwithstanding the promulgation of the 2012 primary 
annual PM2.5 NAAQS under Sec. 50.18. The 1997 primary annual 
PM2.5 NAAQS set forth in this section will no longer apply 
upon the effective date of the final Fine Particulate Matter National 
Ambient Air Quality Standards: State Implementation Plan Requirements 
rule; except that for areas designated nonattainment for the 1997 annual 
PM2.5 NAAQS set forth in this section as of the effective 
date of the final Fine Particulate Matter National Ambient Air Quality 
Standards: State Implementation Plan Requirements rule, the requirements 
applicable to the 1997 primary annual PM2.5 NAAQS set forth 
in this section will apply until the effective date of an area's 
redesignation to attainment for the 1997 annual PM2.5 NAAQS 
pursuant to the requirements of section 107 of the Clean Air Act. The 
1997 secondary annual PM2.5 NAAQS and the 1997 24-hour 
PM2.5 NAAQS shall remain in effect. The area designations and 
classifications with respect to the 1997 annual and 24-hour 
PM2.5 NAAQS remain codified in 40 CFR part 81 in order to 
provide information on where the 1997 primary annual PM2.5 
NAAQS has been revoked and to facilitate the implementation of the 1997 
secondary annual PM2.5 NAAQS and the 1997 24-hour 
PM2.5 NAAQS.

[71 FR 61224, Oct. 17, 2006, as amended at 81 FR 58149, Aug. 24, 2016]



Sec. 50.14  Treatment of air quality monitoring data influenced by
exceptional events.

    (a) Requirements--(1) Scope. (i) This section applies to the 
treatment of data showing exceedances or violations of any national 
ambient air quality standard for purposes of the following types of 
regulatory determinations by the Administrator:
    (A) An action to designate an area, pursuant to Clean Air Act 
section 107(d)(1), or redesignate an area, pursuant to Clean Air Act 
section 107(d)(3), for a particular national ambient air quality 
standard;
    (B) The assignment or re-assignment of a classification category to 
a nonattainment area where such classification is based on a comparison 
of pollutant design values, calculated according

[[Page 12]]

to the specific data handling procedures in 40 CFR part 50 for each 
national ambient air quality standard, to the level of the relevant 
national ambient air quality standard;
    (C) A determination regarding whether a nonattainment area has 
attained the level of the appropriate national ambient air quality 
standard by its specified deadline;
    (D) A determination that an area has data for the specific NAAQS, 
which qualify the area for an attainment date extension under the CAA 
provisions for the applicable pollutant;
    (E) A determination under Clean Air Act section 110(k)(5), if based 
on an area violating a national ambient air quality standard, that the 
state implementation plan is inadequate under the requirements of Clean 
Air Act section 110; and
    (F) Other actions on a case-by-case basis as determined by the 
Administrator.
    (ii) A State, federal land manager or other federal agency may 
request the Administrator to exclude data showing exceedances or 
violations of any national ambient air quality standard that are 
directly due to an exceptional event from use in determinations 
identified in paragraph (a)(1)(i) of this section by demonstrating to 
the Administrator's satisfaction that such event caused a specific air 
pollution concentration at a particular air quality monitoring location.
    (A) For a federal land manager or other federal agency to be 
eligible to initiate such a request for data exclusion, the federal land 
manager or other federal agency must:
    (1) Either operate a regulatory monitor that has been affected by an 
exceptional event or manage land on which an exceptional event occurred 
that influenced a monitored concentration at a regulatory monitor; and
    (2) Initiate such a request only after the State in which the 
affected monitor is located concurs with the federal land manager's or 
other federal agency's submittal.
    (B) With regard to such a request, all provisions in this section 
that are expressed as requirements applying to a State shall, except as 
noted, be requirements applying to the federal land manager or other 
federal agency.
    (C) Provided all provisions in this section are met, the 
Administrator shall allow a State to submit demonstrations for any 
regulatory monitor within its jurisdictional bounds, including those 
operated by federal land managers, other federal agencies and delegated 
local agencies.
    (D) Where multiple agencies within a state submit demonstrations for 
events that meet the requirements of the Exceptional Events Rule, a 
State submittal shall have primacy for any regulatory monitor within its 
jurisdictional bounds.
    (2) A demonstration to justify data exclusion may include any 
reliable and accurate data, but must specifically address the elements 
in paragraphs (c)(3)(iv) and (v) of this section.
    (b) Determinations by the Administrator--(1) Generally. The 
Administrator shall exclude data from use in determinations of 
exceedances and violations identified in paragraph (a)(1)(i) of this 
section where a State demonstrates to the Administrator's satisfaction 
that an exceptional event caused a specific air pollution concentration 
at a particular air quality monitoring location and otherwise satisfies 
the requirements of this section.
    (2) Fireworks displays. The Administrator shall exclude data from 
use in determinations of exceedances and violations where a State 
demonstrates to the Administrator's satisfaction that emissions from 
fireworks displays caused a specific air pollution concentration in 
excess of one or more national ambient air quality standards at a 
particular air quality monitoring location and otherwise satisfies the 
requirements of this section. Such data will be treated in the same 
manner as exceptional events under this rule, provided a State 
demonstrates that such use of fireworks is significantly integral to 
traditional national, ethnic, or other cultural events including, but 
not limited to, July Fourth celebrations that satisfy the requirements 
of this section.
    (3) Prescribed fires. (i) The Administrator shall exclude data from 
use in determinations of exceedances and violations, where a State 
demonstrates to

[[Page 13]]

the Administrator's satisfaction that emissions from prescribed fires 
caused a specific air pollution concentration in excess of one or more 
national ambient air quality standards at a particular air quality 
monitoring location and otherwise satisfies the requirements of this 
section.
    (ii) In addressing the requirements set forth in paragraph 
(c)(3)(iv)(D) of this section regarding the not reasonably controllable 
or preventable criterion:
    (A) With respect to the requirement that a prescribed fire be not 
reasonably controllable, the State must either certify to the 
Administrator that it has adopted and is implementing a smoke management 
program or the State must demonstrate that the burn manager employed 
appropriate basic smoke management practices identified in Table 1 to 
Sec. 50.14. Where a burn manager employs appropriate basic smoke 
management practices, the State may rely on a statement or other 
documentation provided by the burn manager that he or she employed those 
practices. If an exceedance or violation of a NAAQS occurs when a 
prescribed fire is employing an appropriate basic smoke management 
practices approach, the State and the burn manager must undertake a 
review of the subject fire, including a review of the basic smoke 
management practices applied during the subject fire to ensure the 
protection of air quality and public health and progress towards 
restoring and/or maintaining a sustainable and resilient wildland 
ecosystem. If the prescribed fire becomes the subject of an exceptional 
events demonstration, documentation of the post-burn review must 
accompany the demonstration.
    (B) If the State anticipates satisfying the requirements of 
paragraph (c)(3)(iv)(D) of this section by employing the appropriate 
basic smoke management practices identified in Table 1 to Sec. 50.14, 
then:
    (1) The State, federal land managers, and other entities as 
appropriate, must periodically collaborate with burn managers operating 
within the jurisdiction of the State to discuss and document the process 
by which air agencies and land managers will work together to protect 
public health and manage air quality impacts during the conduct of 
prescribed fires on wildland. Such discussions must include outreach and 
education regarding general expectations for the selection and 
application of appropriate basic smoke management practices and goals 
for advancing strategies and increasing adoption and communication of 
the benefits of appropriate basic smoke management practices;
    (2) The State, federal land managers and burn managers shall have an 
initial implementation period, defined as being 2 years from September 
30, 2016, to implement the collaboration and outreach effort identified 
in paragraph (b)(3)(ii)(B)(1) of this section; and
    (3) Except as provided in paragraph (b)(3)(ii)(B)(2) of this 
section, the Administrator shall not place a concurrence flag in the 
appropriate field for the data record in the AQS database, as specified 
in paragraph (c)(2)(ii) of this section, if the data are associated with 
a prescribed fire on wildland unless the requirements of paragraph 
(b)(3)(ii)(B)(1) of this section have been met and associated 
documentation accompanies any applicable exceptional events 
demonstration. The Administrator may nonconcur or defer action on such a 
demonstration.
    (C) With respect to the requirement that a prescribed fire be not 
reasonably preventable, the State may rely upon and reference a multi-
year land or resource management plan for a wildland area with a stated 
objective to establish, restore and/or maintain a sustainable and 
resilient wildland ecosystem and/or to preserve endangered or threatened 
species through a program of prescribed fire provided that the 
Administrator determines that there is no compelling evidence to the 
contrary in the record and the use of prescribed fire in the area has 
not exceeded the frequency indicated in that plan.
    (iii) Provided the Administrator determines that there is no 
compelling evidence to the contrary in the record, in addressing the 
requirements set forth in paragraph (c)(3)(iv)(E) of this section 
regarding the human activity unlikely to recur at a particular location 
criterion for demonstrations involving prescribed fires on wildland,

[[Page 14]]

the State must describe the actual frequency with which a burn was 
conducted, but may rely upon and reference an assessment of the natural 
fire return interval or the prescribed fire frequency needed to 
establish, restore and/or maintain a sustainable and resilient wildland 
ecosystem contained in a multi-year land or resource management plan 
with a stated objective to establish, restore and/or maintain a 
sustainable and resilient wildland ecosystem and/or to preserve 
endangered or threatened species through a program of prescribed fire.

  Table 1 to Sec. 50.14--Summary of Basic Smoke Management Practices,
         Benefit Achieved With the BSMP, and When it is Applieda
------------------------------------------------------------------------
                                                        When the BSMP is
    Basic Smoke Management      Benefit achieved with   applied--before/
         Practice \b\                  the BSMP         during/after the
                                                              burn
------------------------------------------------------------------------
Evaluate Smoke Dispersion       Minimize smoke         Before, During,
 Conditions.                     impacts.               After.
Monitor Effects on Air Quality  Be aware of where the  Before, During,
                                 smoke is going and     After.
                                 degree it impacts
                                 air quality.
Record-Keeping/Maintain a Burn/ Retain information     Before, During,
 Smoke Journal.                  about the weather,     After.
                                 burn and smoke. If
                                 air quality problems
                                 occur, documentation
                                 helps analyze and
                                 address air
                                 regulatory issues..
Communication--Public           Notify neighbors and   Before, During.
 Notification.                   those potentially
                                 impacted by smoke,
                                 especially sensitive
                                 receptors.
Consider Emission Reduction     Reducing emissions     Before, During,
 Techniques.                     through mechanisms     After.
                                 such as reducing
                                 fuel loading can
                                 reduce downwind
                                 impacts.
Share the Airshed--             Coordinate multiple    Before, During,
 Coordination of Area Burning.   burns in the area to   After.
                                 manage exposure of
                                 the public to smoke.
------------------------------------------------------------------------
\a\ The EPA believes that elements of these BSMP could also be practical
  and beneficial to apply to wildfires for areas likely to experience
  recurring wildfires.
\b\ The listing of BSMP in this table is not intended to be all-
  inclusive. Not all BSMP are appropriate for all burns. Goals for
  applicability should retain flexibility to allow for onsite variation
  and site-specific conditions that can be variable on the day of the
  burn. Burn managers can consider other appropriate BSMP as they become
  available due to technological advancement or programmatic refinement.

    (4) Wildfires. The Administrator shall exclude data from use in 
determinations of exceedances and violations where a State demonstrates 
to the Administrator's satisfaction that emissions from wildfires caused 
a specific air pollution concentration in excess of one or more national 
ambient air quality standard at a particular air quality monitoring 
location and otherwise satisfies the requirements of this section. 
Provided the Administrator determines that there is no compelling 
evidence to the contrary in the record, the Administrator will determine 
every wildfire occurring predominantly on wildland to have met the 
requirements identified in paragraph (c)(3)(iv)(D) of this section 
regarding the not reasonably controllable or preventable criterion.
    (5) High wind dust events. (i) The Administrator shall exclude data 
from use in determinations of exceedances and violations, where a State 
demonstrates to the Administrator's satisfaction that emissions from a 
high wind dust event caused a specific air pollution concentration in 
excess of one or more national ambient air quality standards at a 
particular air quality monitoring location and otherwise satisfies the 
requirements of this section provided that such emissions are from high 
wind dust events.
    (ii) The Administrator will consider high wind dust events to be 
natural events in cases where windblown dust is entirely from natural 
undisturbed lands in the area or where all anthropogenic sources are 
reasonably controlled as determined in accordance with paragraph (b)(8) 
of this section.
    (iii) The Administrator will accept a high wind threshold of a 
sustained wind of 25 mph for areas in the States of Arizona, California, 
Colorado, Kansas, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, 
South Dakota, Texas, Utah, and Wyoming provided this value is not 
contradicted by evidence in the record at the time the State submits a 
demonstration. In lieu of this threshold, States can identify

[[Page 15]]

and use an Administrator-approved alternate area-specific high wind 
threshold that is more representative of local or regional conditions, 
if appropriate.
    (iv) In addressing the requirements set forth in paragraph 
(c)(3)(iv)(D) of this section regarding the not reasonably preventable 
criterion, the State shall not be required to provide a case-specific 
justification for a high wind dust event.
    (v) With respect to the not reasonably controllable criterion of 
paragraph (c)(3)(iv)(D) of this section, dust controls on an 
anthropogenic source shall be considered reasonable in any case in which 
the controls render the anthropogenic source as resistant to high winds 
as natural undisturbed lands in the area affected by the high wind dust 
event. The Administrator may determine lesser controls reasonable on a 
case-by-case basis.
    (vi) For large-scale and high-energy high wind dust events, the 
Administrator will generally consider a demonstration documenting the 
nature and extent of the event to be sufficient with respect to the not 
reasonably controllable criterion of paragraph (c)(3)(iv)(D) of this 
section provided the State provides evidence showing that the event 
satisfies the following:
    (A) The event is associated with a dust storm and is the focus of a 
Dust Storm Warning.
    (B) The event has sustained winds that are greater than or equal to 
40 miles per hour.
    (C) The event has reduced visibility equal to or less than 0.5 
miles.
    (6) Stratospheric Intrusions. Where a State demonstrates to the 
Administrator's satisfaction that emissions from stratospheric 
intrusions caused a specific air pollution concentration in excess of 
one or more national ambient air quality standard at a particular air 
quality monitoring location and otherwise satisfies the requirements of 
this section, the Administrator will determine stratospheric intrusions 
to have met the requirements identified in paragraph (c)(3)(iv)(D) of 
this section regarding the not reasonably controllable or preventable 
criterion and shall exclude data from use in determinations of 
exceedances and violations.
    (7) Determinations with respect to event aggregation, multiple 
national ambient air quality standards for the same pollutant, and 
exclusion of 24-hour values for particulate matter.
    (i) Where a State demonstrates to the Administrator's satisfaction 
that for national ambient air quality standards with averaging or 
cumulative periods less than or equal to 24 hours the aggregate effect 
of events occurring on the same day has caused an exceedance or 
violation, the Administrator shall determine such collective data to 
satisfy the requirements in paragraph (c)(3)(iv)(B) of this section 
regarding the clear causal relationship criterion. Where a State 
demonstrates to the Administrator's satisfaction that for national 
ambient air quality standards with averaging or cumulative periods 
longer than 24 hours the aggregate effect of events occurring on 
different days has caused an exceedance or violation, the Administrator 
shall determine such collective data to satisfy the requirements in 
paragraph (c)(3)(iv)(B) of this section regarding the clear causal 
relationship criterion.
    (ii) The Administrator shall accept as part of a demonstration for 
the clear causal relationship in paragraph (c)(3)(iv)(B) of this section 
with respect to a 24-hour NAAQS, a State's comparison of a 24-hour 
concentration of any national ambient air quality standard pollutant to 
the level of a national ambient air quality standard for the same 
pollutant with a longer averaging period. The Administrator shall also 
accept as part of a demonstration for the clear causal relationship in 
paragraph (c)(3)(iv)(B) of this section with respect to a NAAQS with a 
longer averaging period, a State's comparison of a 24-hour concentration 
of any national ambient air quality standard pollutant to the level of 
the national ambient air quality standard for the same pollutant with a 
longer averaging period, without the State having to demonstrate that 
the event caused the annual average concentration of the pollutant to 
exceed the level of the NAAQS with the longer averaging period.
    (iii) Where a State operates a continuous analyzer that has been 
designated

[[Page 16]]

as a Federal Equivalent Method monitor as defined in 40 CFR 50.1(g) that 
complies with the monitoring requirements of 40 CFR part 58, Appendix C, 
and the State believes that collected data have been influenced by an 
event, in following the process outlined in paragraph (c)(2) of this 
section, the State shall create an initial event description and flag 
the associated event-influenced data that have been submitted to the AQS 
database for the affected monitor. Where a State demonstrates to the 
Administrator's satisfaction that such data satisfy the requirements in 
paragraph (c)(3)(iv)(B) of this section regarding the clear causal 
relationship criterion and otherwise satisfy the requirements of this 
section, the Administrator shall agree to exclude all data within the 
affected calendar day(s).
    (8) Determinations with respect to the not reasonably controllable 
or preventable criterion. (i) The not reasonably controllable or 
preventable criterion has two prongs that the State must demonstrate: 
prevention and control.
    (ii) The Administrator shall determine that an event is not 
reasonably preventable if the State shows that reasonable measures to 
prevent the event were applied at the time of the event.
    (iii) The Administrator shall determine that an event is not 
reasonably controllable if the State shows that reasonable measures to 
control the impact of the event on air quality were applied at the time 
of the event.
    (iv) The Administrator shall assess the reasonableness of available 
controls for anthropogenic sources based on information available as of 
the date of the event.
    (v) Except where a State, tribal or federal air agency is obligated 
to revise its state implementation plan, tribal implementation plan, or 
federal implementation plan, the Administrator shall consider 
enforceable control measures implemented in accordance with a state 
implementation plan, tribal implementation plan, or federal 
implementation plan, approved by the EPA within 5 years of the date of 
the event, that address the event-related pollutant and all sources 
necessary to fulfill the requirements of the Clean Air Act for the state 
implementation plan, tribal implementation plan, or federal 
implementation plan to be reasonable controls with respect to all 
anthropogenic sources that have or may have contributed to the monitored 
exceedance or violation.
    (vi) Where a State, tribal or federal air agency is obligated to 
revise its state implementation plan, tribal implementation plan, or 
federal implementation plan, the deference to enforceable control 
measures identified in paragraph (b)(8)(v) of this section shall remain 
only until the due date of the required state implementation plan, 
tribal implementation plan, or federal implementation plan revisions. 
However, where an air agency is obligated to revise the enforceable 
control measures identified in paragraph (b)(8)(v) of this section in 
its implementation plan as a result of an action pursuant to Clean Air 
Act section 110(k)(5), the deference, if any, to those enforceable 
control measures shall be determined on a case-by-case basis.
    (vii) The Administrator shall not require a State to provide case-
specific justification to support the not reasonably controllable or 
preventable criterion for emissions-generating activity that occurs 
outside of the State's jurisdictional boundaries within which the 
concentration at issue was monitored. In the case of a tribe treated as 
a state under 40 CFR 49.2 with respect to exceptional events 
requirements, the tribe's jurisdictional boundaries for purposes of 
requiring or directly implementing emission controls apply. In the case 
of a federal land manager or other federal agency submitting a 
demonstration under the requirements of this section, the jurisdictional 
boundaries that apply are those of the State or the tribe depending on 
which has jurisdiction over the area where the event has occurred.
    (viii) In addition to the provisions that apply to specific event 
types identified in paragraphs (b)(3)(ii) and (b)(5)(i) through (iii) of 
this section in addressing the requirements set forth in paragraph 
(c)(3)(iv)(D) of this section regarding the not reasonably controllable 
or preventable criterion, the State must include the following 
components:

[[Page 17]]

    (A) Identification of the natural and anthropogenic sources of 
emissions causing and contributing to the monitored exceedance or 
violation, including the contribution from local sources.
    (B) Identification of the relevant state implementation plan, tribal 
implementation plan, or federal implementation plan or other enforceable 
control measures in place for the sources identified in paragraph 
(b)(8)(vii)(A) of this section and the implementation status of these 
controls.
    (C) Evidence of effective implementation and enforcement of the 
measures identified in paragraph (b)(8)(vii)(B) of this section.
    (D) The provisions in this paragraph shall not apply if the 
provisions in paragraph (b)(4), (b)(5)(vi), or (b)(6) of this section 
apply.
    (9) Mitigation plans. (i) Except as provided for in paragraph 
(b)(9)(ii) of this section, where a State is subject to the requirements 
of 40 CFR 51.930(b), the Administrator shall not place a concurrence 
flag in the appropriate field for the data record in the AQS database, 
as specified in paragraph (c)(2)(ii) of this section, if the data are of 
the type and pollutant that are the focus of the mitigation plan until 
the State fulfills its obligations under the requirements of 40 CFR 
51.930(b). The Administrator may nonconcur or defer action on such a 
demonstration.
    (ii) The prohibition on placing a concurrence flag in the 
appropriate field for the data record in the AQS database by the 
Administrator stated in paragraph (b)(9(i) of this section does not 
apply to data that are included in an exceptional events demonstration 
that is:
    (A) submitted in accordance with paragraph (c)(3) of this section 
that is also of the type and pollutant that is the focus of the 
mitigation plan, and
    (B) submitted within the 2-year period allowed for mitigation plan 
development as specified in 40 CFR 51.930(b)(3).
    (c) Schedules and procedures--(1) Public notification. (i) In 
accordance with the mitigation requirement at 40 CFR 51.930(a)(1), all 
States and, where applicable, their political subdivisions must notify 
the public promptly whenever an event occurs or is reasonably 
anticipated to occur which may result in the exceedance of an applicable 
air quality standard.
    (ii) [Reserved]
    (2) Initial notification of potential exceptional event. (i) A State 
shall notify the Administrator of its intent to request exclusion of one 
or more measured exceedances of an applicable national ambient air 
quality standard as being due to an exceptional event by creating an 
initial event description and flagging the associated data that have 
been submitted to the AQS database and by engaging in the Initial 
Notification of Potential Exceptional Event process as follows:
    (A) The State and the appropriate EPA Regional office shall engage 
in regular communications to identify those data that have been 
potentially influenced by an exceptional event, to determine whether the 
identified data may affect a regulatory determination and to discuss 
whether the State should develop and submit an exceptional events 
demonstration according to the requirements in this section;
    (B) For data that may affect an anticipated regulatory determination 
or where circumstances otherwise compel the Administrator to prioritize 
the resulting demonstration, the Administrator shall respond to a 
State's Initial Notification of Potential Exceptional Event with a due 
date for demonstration submittal that considers the nature of the event 
and the anticipated timing of the associated regulatory decision;
    (C) The Administrator may waive the Initial Notification of 
Potential Exceptional Event process on a case-by-case basis.
    (ii) The data shall not be excluded from determinations with respect 
to exceedances or violations of the national ambient air quality 
standards unless and until, following the State's submittal of its 
demonstration pursuant to paragraph (c)(3) of this section and the 
Administrator's review, the Administrator notifies the State of its 
concurrence by placing a concurrence flag in the appropriate field for 
the data record in the AQS database.
    (iii) [Reserved]
    (iv) [Reserved]

[[Page 18]]

    (v) [Reserved]
    (vi) Table 2 to Sec. 50.14 identifies the submission process for 
data that will or may influence the initial designation of areas for any 
new or revised national ambient air quality standard.

     Table 2 to Sec. 50.14--Schedule for Initial Notification and
 Demonstration Submission for Data Influenced by Exceptional Events for
                    Use in Initial Area Designations
------------------------------------------------------------------------
 Exceptional events/Regulatory                       Exceptional events
            action                  Condition      deadline schedule \d\
------------------------------------------------------------------------
(A) Initial Notification        If state and       then the Initial
 deadline for data years 1, 2    tribal initial     Notification
 and 3.\a\.                      designation        deadline will be the
                                 recommendations    July 1 prior to the
                                 for a new/         recommendation
                                 revised national   deadline.
                                 ambient air
                                 quality standard
                                 are due August
                                 through January,
(B) Initial Notification        If state and       then the Initial
 deadline for data years 1, 2    tribal             Notification
 and 3.\a\.                      recommendations    deadline will be the
                                 for a new/         January 1 prior to
                                 revised national   the recommendation
                                 ambient air        deadline.
                                 quality standard
                                 are due February
                                 through July,
(C) Exceptional events          None.............  no later than the
 demonstration submittal                            later of November
 deadline for data years 1, 2                       29, 2016 or the date
 and 3 \a\.                                         that state and
                                                    tribal
                                                    recommendations are
                                                    due to the
                                                    Administrator.
(D) Initial Notification and    None.............  by the last day of
 exceptional events                                 the month that is 1
 demonstration submittal                            year and 7 months
 deadline for data year 4 \b\                       after promulgation
 and, where applicable, data                        of a new/revised
 year 5.\c\.                                        national ambient air
                                                    quality standard,
                                                    unless either
                                                    paragraph (E) or
                                                    paragraph (F)
                                                    applies.
(E) Initial Notification and    If the             the deadline is 2
 exceptional events              Administrator      years and 7 months
 demonstration submittal         follows a 3-year   after promulgation
 deadline for data year 4 \b\    designation        of a new/revised
 and, where applicable, data     schedule.          national ambient air
 year 5.\c\.                                        quality standard.
(F) Initial Notification and    If the             the deadline is 5
 exceptional events              Administrator      months prior to the
 demonstration submittal         notifies the       date specified for
 deadline for data year 4 \b\    state/tribe that   final designations
 and, where applicable, data     it intends to      decisions in such
 year 5.\c\.                     complete the       Administrator
                                 initial area       notification.
                                 designations
                                 process
                                 according to a
                                 schedule between
                                 2 and 3 years,.
------------------------------------------------------------------------
\a\ Where data years 1, 2, and 3 are those years expected to be
  considered in state and tribal recommendations.
\b\ Where data year 4 is the additional year of data that the
  Administrator may consider when making final area designations for a
  new/revised national ambient air quality standard under the standard
  designations schedule.
\c\ Where data year 5 is the additional year of data that the
  Administrator may consider when making final area designations for a
  new/revised national ambient air quality standard under an extended
  designations schedule.
\d\ The date by which air agencies must certify their ambient air
  quality monitoring data in AQS is annually on May 1 of the year
  following the year of data collection as specified in 40 CFR
  58.15(a)(2). In some cases, however, air agencies may choose to
  certify a prior year's data in advance of May 1 of the following year,
  particularly if the Administrator has indicated intent to promulgate
  final designations in the first 8 months of the calendar year.
  Exceptional events demonstration deadlines for ``early certified''
  data will follow the deadlines for ``year 4'' and ``year 5'' data.

    (3) Submission of demonstrations. (i) Except as provided under 
paragraph (c)(2)(vi) of this section, a State that has flagged data as 
being due to an exceptional event and is requesting exclusion of the 
affected measurement data shall, after notice and opportunity for public 
comment, submit a demonstration to justify data exclusion to the 
Administrator according to the schedule established under paragraph 
(c)(2)(i)(B).
    (ii) [Reserved]
    (iii) [Reserved]
    (iv) The demonstration to justify data exclusion must include:
    (A) A narrative conceptual model that describes the event(s) causing 
the exceedance or violation and a discussion of how emissions from the 
event(s) led to the exceedance or violation at the affected monitor(s);
    (B) A demonstration that the event affected air quality in such a 
way that there exists a clear causal relationship between the specific 
event and the monitored exceedance or violation;
    (C) Analyses comparing the claimed event-influenced concentration(s) 
to concentrations at the same monitoring site at other times to support 
the requirement at paragraph (c)(3)(iv)(B) of this section. The 
Administrator shall not require a State to prove a specific percentile 
point in the distribution of data;
    (D) A demonstration that the event was both not reasonably 
controllable and not reasonably preventable; and

[[Page 19]]

    (E) A demonstration that the event was a human activity that is 
unlikely to recur at a particular location or was a natural event.
    (v) With the submission of the demonstration containing the elements 
in paragraph (c)(3)(iv) of this section, the State must:
    (A) Document that the State followed the public comment process and 
that the comment period was open for a minimum of 30 days, which could 
be concurrent with the beginning of the Administrator's initial review 
period of the associated demonstration provided the State can meet all 
requirements in this paragraph;
    (B) Submit the public comments it received along with its 
demonstration to the Administrator; and
    (C) Address in the submission to the Administrator those comments 
disputing or contradicting factual evidence provided in the 
demonstration.
    (vi) Where the State has submitted a demonstration according to the 
requirements of this section after September 30, 2016 and the 
Administrator has reviewed such demonstration and requested additional 
evidence to support one of the elements in paragraph (c)(3)(iv) of this 
section, the State shall have 12 months from the date of the 
Administrator's request to submit such evidence. At the conclusion of 
this time, if the State has not submitted the requested additional 
evidence, the Administrator will notify the State in writing that it 
considers the demonstration to be inactive and will not pursue 
additional review of the demonstration. After a 12-month period of 
inactivity by the State, if a State desires to pursue the inactive 
demonstration, it must reinitiate its request to exclude associated data 
by following the process beginning with paragraph (c)(2)(i) of this 
section.

[81 FR 68277, Oct. 3, 2016]



Sec. 50.15  National primary and secondary ambient air quality
standards for ozone.

    (a) The level of the national 8-hour primary and secondary ambient 
air quality standards for ozone (O3) is 0.075 parts per 
million (ppm), daily maximum 8-hour average, measured by a reference 
method based on appendix D to this part and designated in accordance 
with part 53 of this chapter or an equivalent method designated in 
accordance with part 53 of this chapter.
    (b) The 8-hour primary and secondary O3 ambient air 
quality standards are met at an ambient air quality monitoring site when 
the 3-year average of the annual fourth-highest daily maximum 8-hour 
average O3 concentration is less than or equal to 0.075 ppm, 
as determined in accordance with appendix P to this part.

[73 FR 16511, Mar. 27, 2008]



Sec. 50.16  National primary and secondary ambient air quality
standards for lead.

    (a) The national primary and secondary ambient air quality standards 
for lead (Pb) and its compounds are 0.15 micrograms per cubic meter, 
arithmetic mean concentration over a 3-month period, measured in the 
ambient air as Pb either by:
    (1) A reference method based on appendix G of this part and 
designated in accordance with part 53 of this chapter or;
    (2) An equivalent method designated in accordance with part 53 of 
this chapter.
    (b) The national primary and secondary ambient air quality standards 
for Pb are met when the maximum arithmetic 3-month mean concentration 
for a 3-year period, as determined in accordance with appendix R of this 
part, is less than or equal to 0.15 micrograms per cubic meter.

[73 FR 67052, Nov. 12, 2008]



Sec. 50.17  National primary ambient air quality standards for sulfur 
oxides (sulfur dioxide).

    (a) The level of the national primary 1-hour annual ambient air 
quality standard for oxides of sulfur is 75 parts per billion (ppb, 
which is 1 part in 1,000,000,000), measured in the ambient air as sulfur 
dioxide (SO2).
    (b) The 1-hour primary standard is met at an ambient air quality 
monitoring site when the three-year average of the annual (99th 
percentile) of the daily maximum 1-hour average concentrations is less 
than or equal to 75 ppb, as determined in accordance with appendix T of 
this part.

[[Page 20]]

    (c) The level of the standard shall be measured by a reference 
method based on appendix A or A-1 of this part, or by a Federal 
Equivalent Method (FEM) designated in accordance with part 53 of this 
chapter.

[75 FR 35592, June 22, 2010]



Sec. 50.18  National primary ambient air quality standards for PM2.5.

    (a) The national primary ambient air quality standards for 
PM2.5 are 12.0 micrograms per cubic meter ([micro]g/m\3\) 
annual arithmetic mean concentration and 35 [micro]g/m\3\ 24-hour 
average concentration measured in the ambient air as PM2.5 
(particles with an aerodynamic diameter less than or equal to a nominal 
2.5 micrometers) by either:
    (1) A reference method based on appendix L to this part and 
designated in accordance with part 53 of this chapter; or
    (2) An equivalent method designated in accordance with part 53 of 
this chapter.
    (b) The primary annual PM2.5 standard is met when the 
annual arithmetic mean concentration, as determined in accordance with 
appendix N of this part, is less than or equal to 12.0 [micro]g/m\3\.
    (c) The primary 24-hour PM2.5 standard is met when the 
98th percentile 24-hour concentration, as determined in accordance with 
appendix N of this part, is less than or equal to 35 [micro]g/m\3\.

[78 FR 3277, Jan. 15, 2013]



Sec. 50.19  National primary and secondary ambient air quality 
standards for ozone.

    (a) The level of the national 8-hour primary ambient air quality 
standard for ozone (O3) is 0.070 parts per million (ppm), 
daily maximum 8-hour average, measured by a reference method based on 
appendix D to this part and designated in accordance with part 53 of 
this chapter or an equivalent method designated in accordance with part 
53 of this chapter.
    (b) The 8-hour primary O3 ambient air quality standard is 
met at an ambient air quality monitoring site when the 3-year average of 
the annual fourth-highest daily maximum 8-hour average O3 
concentration is less than or equal to 0.070 ppm, as determined in 
accordance with appendix U to this part.
    (c) The level of the national secondary ambient air quality standard 
for O3 is 0.070 ppm, daily maximum 8-hour average, measured 
by a reference method based on appendix D to this part and designated in 
accordance with part 53 of this chapter or an equivalent method 
designated in accordance with part 53 of this chapter.
    (d) The 8-hour secondary O3 ambient air quality standard 
is met at an ambient air quality monitoring site when the 3-year average 
of the annual fourth-highest daily maximum 8-hour average O3 
concentration is less than or equal to 0.070 ppm, as determined in 
accordance with appendix U to this part.

[80 FR 65452, Oct. 26, 2015]



   Sec. Appendix A-1 to Part 50--Reference Measurement Principle and 
   Calibration Procedure for the Measurement of Sulfur Dioxide in the 
              Atmosphere (Ultraviolet Fluorescence Method)

                            1.0 Applicability

    1.1 This ultraviolet fluorescence (UVF) method provides a 
measurement of the concentration of sulfur dioxide (SO2) in 
ambient air for determining compliance with the national primary and 
secondary ambient air quality standards for sulfur oxides (sulfur 
dioxide) as specified in Sec. 50.4, Sec. 50.5, and Sec. 50.17 of this 
chapter. The method is applicable to the measurement of ambient 
SO2 concentrations using continuous (real-time) sampling. 
Additional quality assurance procedures and guidance are provided in 
part 58, appendix A, of this chapter and in Reference 3.

                              2.0 Principle

    2.1 This reference method is based on automated measurement of the 
intensity of the characteristic fluorescence released by SO2 
in an ambient air sample contained in a measurement cell of an analyzer 
when the air sample is irradiated by ultraviolet (UV) light passed 
through the cell. The fluorescent light released by the SO2 
is also in the ultraviolet region, but at longer wavelengths than the 
excitation light. Typically, optimum instrumental measurement of 
SO2 concentrations is obtained with an excitation wavelength 
in a band between approximately 190 to 230 nm, and measurement of the 
SO2 fluorescence in a broad band around 320 nm, but these 
wavelengths are not necessarily

[[Page 21]]

constraints of this reference method. Generally, the measurement system 
(analyzer) also requires means to reduce the effects of aromatic 
hydrocarbon species, and possibly other compounds, in the air sample to 
control measurement interferences from these compounds, which may be 
present in the ambient air. References 1 and 2 describe UVF method.
    2.2 The measurement system is calibrated by referencing the 
instrumental fluorescence measurements to SO2 standard 
concentrations traceable to a National Institute of Standards and 
Technology (NIST) primary standard for SO2 (see Calibration 
Procedure below).
    2.3 An analyzer implementing this measurement principle is shown 
schematically in Figure 1. Designs should include a measurement cell, a 
UV light source of appropriate wavelength, a UV detector system with 
appropriate wave length sensitivity, a pump and flow control system for 
sampling the ambient air and moving it into the measurement cell, sample 
air conditioning components as necessary to minimize measurement 
interferences, suitable control and measurement processing capability, 
and other apparatus as may be necessary. The analyzer must be designed 
to provide accurate, repeatable, and continuous measurements of 
SO2 concentrations in ambient air, with measurement 
performance as specified in Subpart B of Part 53 of this chapter.
    2.4 Sampling considerations: The use of a particle filter on the 
sample inlet line of a UVF SO2 analyzer is required to 
prevent interference, malfunction, or damage due to particles in the 
sampled air.

                            3.0 Interferences

    3.1 The effects of the principal potential interferences may need to 
be mitigated to meet the interference equivalent requirements of part 53 
of this chapter. Aromatic hydrocarbons such as xylene and naphthalene 
can fluoresce and act as strong positive interferences. These gases can 
be removed by using a permeation type scrubber (hydrocarbon ``kicker''). 
Nitrogen oxide (NO) in high concentrations can also fluoresce and cause 
positive interference. Optical filtering can be employed to improve the 
rejection of interference from high NO. Ozone can absorb UV light given 
off by the SO2 molecule and cause a measurement offset. This 
effect can be reduced by minimizing the measurement path length between 
the area where SO2 fluorescence occurs and the 
photomultiplier tube detector (e.g., <5 cm). A hydrocarbon scrubber, 
optical filter and appropriate distancing of the measurement path length 
may be required method components to reduce interference.

                        4.0 Calibration Procedure

    Atmospheres containing accurately known concentrations of sulfur 
dioxide are prepared using a compressed gas transfer standard diluted 
with accurately metered clean air flow rates.
    4.1 Apparatus: Figure 2 shows a typical generic system suitable for 
diluting a SO2 gas cylinder concentration standard with clean 
air through a mixing chamber to produce the desired calibration 
concentration standards. A valve may be used to conveniently divert the 
SO2 from the sampling manifold to provide clean zero air at 
the output manifold for zero adjustment. The system may be made up using 
common laboratory components, or it may be a commercially manufactured 
system. In either case, the principle components are as follows:
    4.1.1 SO2 standard gas flow control and measurement 
devices (or a combined device) capable of regulating and maintaining the 
standard gas flow rate constant to within 2 
percent and measuring the gas flow rate accurate to within 2, properly calibrated to a NIST-traceable standard.
    4.1.2 Dilution air flow control and measurement devices (or a 
combined device) capable of regulating and maintaining the air flow rate 
constant to within 2 percent and measuring the air 
flow rate accurate to within 2, properly 
calibrated to a NIST-traceable standard.
    4.1.3 Mixing chamber, of an inert material such as glass and of 
proper design to provide thorough mixing of pollutant gas and diluent 
air streams.
    4.1.4 Sampling manifold, constructed of glass, 
polytetrafluoroethylene (PTFE Teflon \TM\), or other suitably inert 
material and of sufficient diameter to insure a minimum pressure drop at 
the analyzer connection, with a vent designed to insure a minimum over-
pressure (relative to ambient air pressure) at the analyzer connection 
and to prevent ambient air from entering the manifold.
    4.1.5 Standard gas pressure regulator, of clean stainless steel with 
a stainless steel diaphragm, suitable for use with a high pressure 
SO2 gas cylinder.

                             4.1.6 Reagents

    4.1.6.1 SO2 gas concentration transfer standard having a 
certified SO2 concentration of not less than 10 ppm, in 
N2, traceable to a NIST Standard Reference Material (SRM).
    4.1.6.2 Clean zero air, free of contaminants that could cause a 
detectable response or a change in sensitivity of the analyzer. Since 
ultraviolet fluorescence analyzers may be sensitive to aromatic 
hydrocarbons and O2-to-N2 ratios, it is important 
that the clean zero air contains less than 0.1 ppm aromatic hydrocarbons 
and O2 and N2 percentages approximately the same 
as in ambient air. A

[[Page 22]]

procedure for generating zero air is given in reference 1.

                              4.2 Procedure

    4.2.1 Obtain a suitable calibration apparatus, such as the one shown 
schematically in Figure 1, and verify that all materials in contact with 
the pollutant are of glass, Teflon \TM\, or other suitably inert 
material and completely clean.
    4.2.2 Purge the SO2 standard gas lines and pressure 
regulator to remove any residual air.
    4.2.3 Ensure that there are no leaks in the system and that the flow 
measuring devices are properly and accurately calibrated under the 
conditions of use against a reliable volume or flow rate standard such 
as a soap-bubble meter or a wet-test meter traceable to a NIST standard. 
All volumetric flow rates should be corrected to the same reference 
temperature and pressure by using the formula below:
[GRAPHIC] [TIFF OMITTED] TR22JN10.000

Where:

Fc = corrected flow rate (L/min at 25 [deg]C and 760 mm Hg),
Fm = measured flow rate, (at temperature, Tm and pressure, 
          Pm),
Pm = measured pressure in mm Hg, (absolute), and
Tm = measured temperature in degrees Celsius.

    4.2.4 Allow the SO2 analyzer under calibration to sample 
zero air until a stable response is obtained, then make the proper zero 
adjustment.
    4.2.5 Adjust the airflow to provide an SO2 concentration 
of approximately 80 percent of the upper measurement range limit of the 
SO2 instrument and verify that the total air flow of the 
calibration system exceeds the demand of all analyzers sampling from the 
output manifold (with the excess vented).
    4.2.6 Calculate the actual SO2 calibration concentration 
standard as:
[GRAPHIC] [TIFF OMITTED] TR22JN10.001

Where:

C = the concentration of the SO2 gas standard
Fp = the flow rate of SO2 gas standard
Ft = the total air flow rate of pollutant and diluent gases

    4.2.7 When the analyzer response has stabilized, adjust the 
SO2 span control to obtain the desired response equivalent to 
the calculated standard concentration. If substantial adjustment of the 
span control is needed, it may be necessary to re-check the zero and 
span adjustments by repeating steps 4.2.4 through 4.2.7 until no further 
adjustments are needed.
    4.2.8 Adjust the flow rate(s) to provide several other 
SO2 calibration concentrations over the analyzer's 
measurement range. At least five different concentrations evenly spaced 
throughout the analyzer's range are suggested.
    4.2.9 Plot the analyzer response (vertical or Y-axis) versus 
SO2 concentration (horizontal or X-axis). Compute the linear 
regression slope and intercept and plot the regression line to verify 
that no point deviates from this line by more than 2 percent of the 
maximum concentration tested.
    Note: Additional information on calibration and pollutant standards 
is provided in Section 12 of Reference 3.

                      5.0 Frequency of Calibration

    The frequency of calibration, as well as the number of points 
necessary to establish the calibration curve and the frequency of other 
performance checking will vary by analyzer; however, the minimum 
frequency, acceptance criteria, and subsequent actions are specified in 
Reference 3, Appendix D: Measurement Quality Objectives and Validation 
Template for SO2 (page 9 of 30). The user's quality control 
program should provide guidelines for initial establishment of these 
variables and for subsequent alteration as

[[Page 23]]

operational experience is accumulated. Manufacturers of analyzers should 
include in their instruction/operation manuals information and guidance 
as to these variables and on other matters of operation, calibration, 
routine maintenance, and quality control.

                6.0 References for SO2 Method

1. H. Okabe, P. L. Splitstone, and J. J. Ball, ``Ambient and Source 
          SO2 Detector Based on a Fluorescence Method'', 
          Journal of the Air Control Pollution Association, vol. 23, p. 
          514-516 (1973).
2. F. P. Schwarz, H. Okabe, and J. K. Whittaker, ``Fluorescence 
          Detection of Sulfur Dioxide in Air at the Parts per Billion 
          Level,'' Analytical Chemistry, vol. 46, pp. 1024-1028 (1974).
3. QA Handbook for Air Pollution Measurement Systems--Volume II. Ambient 
          Air Quality Monitoring Programs. U.S.
          [GRAPHIC] [TIFF OMITTED] TR22JN10.002
          

[[Page 24]]


[GRAPHIC] [TIFF OMITTED] TR22JN10.003


[75 FR 35593, June 22, 2010]



Sec. Appendix A-2 to Part 50--Reference Method for the Determination of 
        Sulfur Dioxide in the Atmosphere (Pararosaniline Method)

    1.0 Applicability.
    1.1 This method provides a measurement of the concentration of 
sulfur dioxide (SO2) in ambient air for determining 
compliance with the primary and secondary national ambient air quality 
standards for sulfur oxides (sulfur dioxide) as specified in Sec. 50.4 
and Sec. 50.5 of this chapter. The method is applicable to the 
measurement of ambient SO2 concentrations using sampling 
periods ranging from 30 minutes to 24 hours. Additional quality 
assurance procedures and guidance are provided in part 58, appendixes A 
and B, of this chapter and in references 1 and 2.
    2.0 Principle.
    2.1 A measured volume of air is bubbled through a solution of 0.04 M 
potassium tetrachloromercurate (TCM). The SO2 present in the 
air stream reacts with the TCM solution to form a stable 
monochlorosulfonatomercurate(3) complex. Once formed, this complex 
resists air oxidation(4, 5) and is stable in the presence of strong 
oxidants such as ozone and oxides of nitrogen. During subsequent 
analysis, the complex is reacted with acid-bleached pararosaniline dye 
and formaldehyde to form an intensely colored pararosaniline methyl 
sulfonic acid.
    (6) The optical density of this species is determined 
spectrophotometrically at 548 nm and is directly related to the amount 
of SO2 collected. The total volume of air sampled, corrected 
to EPA reference conditions (25 [deg]C, 760 mm Hg [101 kPa]), is 
determined from the measured flow rate and the sampling time. The 
concentration of SO2 in the ambient air is computed and 
expressed in micrograms per standard cubic meter ([micro]g/std m\3\).
    3.0 Range.
    3.1 The lower limit of detection of SO2 in 10 mL of TCM 
is 0.75 [micro]g (based on collaborative

[[Page 25]]

test results).(7) This represents a concentration of 25 [micro]g 
SO2/m\3\ (0.01 ppm) in an air sample of 30 standard liters 
(short-term sampling) and a concentration of 13 [micro]g SO2/
m\3\ (0.005 ppm) in an air sample of 288 standard liters (long-term 
sampling). Concentrations less than 25 [micro]g SO2/m\3\ can 
be measured by sampling larger volumes of ambient air; however, the 
collection efficiency falls off rapidly at low concentrations.(8, 9) 
Beer's law is adhered to up to 34 [micro]g of SO2 in 25 mL of 
final solution. This upper limit of the analysis range represents a 
concentration of 1,130 [micro]g SO2/m\3\ (0.43 ppm) in an air 
sample of 30 standard liters and a concentration of 590 [micro]g 
SO2/m\3\ (0.23 ppm) in an air sample of 288 standard liters. 
Higher concentrations can be measured by collecting a smaller volume of 
air, by increasing the volume of absorbing solution, or by diluting a 
suitable portion of the collected sample with absorbing solution prior 
to analysis.
    4.0 Interferences.
    4.1 The effects of the principal potential interferences have been 
minimized or eliminated in the following manner: Nitrogen oxides by the 
addition of sulfamic acid,(10, 11) heavy metals by the addition of 
ethylenediamine tetracetic acid disodium salt (EDTA) and phosphoric 
acid,(10, 12) and ozone by time delay.(10) Up to 60 [micro]g Fe (III), 
22 [micro]g V (V), 10 [micro]g Cu (II), 10 [micro]g Mn (II), and 10 
[micro]g Cr (III) in 10 mL absorbing reagent can be tolerated in the 
procedure.(10) No significant interference has been encountered with 2.3 
[micro]g NH3.(13)
    5.0 Precision and Accuracy.
    5.1 The precision of the analysis is 4.6 percent (at the 95 percent 
confidence level) based on the analysis of standard sulfite samples.(10)
    5.2 Collaborative test results (14) based on the analysis of 
synthetic test atmospheres (SO2 in scrubbed air) using the 
24-hour sampling procedure and the sulfite-TCM calibration procedure 
show that:

 The replication error varies linearly with 
concentration from 2.5 [micro]g/m\3\ at 
concentrations of 100 [micro]g/m\3\ to 7 [micro]g/
m\3\ at concentrations of 400 [micro]g/m\3\.
 The day-to-day variability within an individual 
laboratory (repeatability) varies linearly with concentration from 
18.1 [micro]g/m\3\ at levels of 100 [micro]g/m\3\ 
to 50.9 [micro]g/m\3\ at levels of 400 [micro]g/
m\3\.
 The day-to-day variability between two or more 
laboratories (reproducibility) varies linearly with concentration from 
36.9 [micro]g/m\3\ at levels of 100 [micro]g/m\3\ 
to 103.5 [micro] g/m\3\ at levels of 400 [micro]g/
m\3\.
 The method has a concentration-dependent bias, which 
becomes significant at the 95 percent confidence level at the high 
concentration level. Observed values tend to be lower than the expected 
SO2 concentration level.

    6.0 Stability.
    6.1 By sampling in a controlled temperature environment of 15[deg] 
10 [deg]C, greater than 98.9 percent of the 
SO2-TCM complex is retained at the completion of sampling. 
(15) If kept at 5 [deg]C following the completion of sampling, the 
collected sample has been found to be stable for up to 30 days. (10) The 
presence of EDTA enhances the stability of SO2 in the TCM 
solution and the rate of decay is independent of the concentration of 
SO2. (16)
    7.0 Apparatus.
    7.1 Sampling.
    7.1.1 Sample probe: A sample probe meeting the requirements of 
section 7 of 40 CFR part 58, appendix E (Teflon [supreg] or glass with 
residence time less than 20 sec.) is used to transport ambient air to 
the sampling train location. The end of the probe should be designed or 
oriented to preclude the sampling of precipitation, large particles, 
etc. A suitable probe can be constructed from Teflon [supreg] tubing 
connected to an inverted funnel.
    7.1.2 Absorber--short-term sampling: An all glass midget impinger 
having a solution capacity of 30 mL and a stem clearance of 4 1 mm from the bottom of the vessel is used for sampling 
periods of 30 minutes and 1 hour (or any period considerably less than 
24 hours). Such an impinger is shown in Figure 1. These impingers are 
commercially available from distributors such as Ace Glass, 
Incorporated.
    7.1.3 Absorber--24-hour sampling: A polypropylene tube 32 mm in 
diameter and 164 mm long (available from Bel Art Products, Pequammock, 
NJ) is used as the absorber. The cap of the absorber must be a 
polypropylene cap with two ports (rubber stoppers are unacceptable 
because the absorbing reagent can react with the stopper to yield 
erroneously high SO2 concentrations). A glass impinger stem, 
6 mm in diameter and 158 mm long, is inserted into one port of the 
absorber cap. The tip of the stem is tapered to a small diameter orifice 
(0.4 0.1 mm) such that a No. 79 jeweler's drill 
bit will pass through the opening but a No. 78 drill bit will not. 
Clearance from the bottom of the absorber to the tip of the stem must be 
6 2 mm. Glass stems can be fabricated by any 
reputable glass blower or can be obtained from a scientific supply firm. 
Upon receipt, the orifice test should be performed to verify the orifice 
size. The 50 mL volume level should be permanently marked on the 
absorber. The assembled absorber is shown in Figure 2.
    7.1.4 Moisture trap: A moisture trap constructed of a glass trap as 
shown in Figure 1 or a polypropylene tube as shown in Figure 2 is placed 
between the absorber tube and flow control device to prevent entrained 
liquid from reaching the flow control device. The tube is packed with 
indicating silica gel as shown in Figure 2. Glass wool may be 
substituted for silica gel when collecting short-term samples (1 hour or 
less) as shown in

[[Page 26]]

Figure 1, or for long term (24 hour) samples if flow changes are not 
routinely encountered.
    7.1.5 Cap seals: The absorber and moisture trap caps must seal 
securely to prevent leaks during use. Heat-shrink material as shown in 
Figure 2 can be used to retain the cap seals if there is any chance of 
the caps coming loose during sampling, shipment, or storage.



[[Page 27]]





[[Page 28]]


    7.1.6 Flow control device: A calibrated rotameter and needle valve 
combination capable of maintaining and measuring air flow to within 
2 percent is suitable for short-term sampling but 
may not be used for long-term sampling. A critical orifice can be used 
for regulating flow rate for both long-term and short-term sampling. A 
22-gauge hypodermic needle 25 mm long may be used as a critical orifice 
to yield a flow rate of approximately 1 L/min for a 30-minute sampling 
period. When sampling for 1 hour, a 23-gauge hypodermic needle 16 mm in 
length will provide a flow rate of approximately 0.5 L/min. Flow control 
for a 24-hour sample may be provided by a 27-gauge hypodermic needle 
critical orifice that is 9.5 mm in length. The flow rate should be in 
the range of 0.18 to 0.22 L/min.
    7.1.7 Flow measurement device: Device calibrated as specified in 
9.4.1 and used to measure sample flow rate at the monitoring site.
    7.1.8 Membrane particle filter: A membrane filter of 0.8 to 2 
[micro]m porosity is used to protect the flow controller from particles 
during long-term sampling. This item is optional for short-term 
sampling.
    7.1.9 Vacuum pump: A vacuum pump equipped with a vacuum gauge and 
capable of maintaining at least 70 kPa (0.7 atm) vacuum differential 
across the flow control device at the specified flow rate is required 
for sampling.
    7.1.10 Temperature control device: The temperature of the absorbing 
solution during sampling must be maintained at 15[deg] 10 [deg]C. As soon as possible following sampling and 
until analysis, the temperature of the collected sample must be 
maintained at 5[deg] 5 [deg]C. Where an extended 
period of time may elapse before the collected sample can be moved to 
the lower storage temperature, a collection temperature near the lower 
limit of the 15 10 [deg]C range should be used to 
minimize losses during this period. Thermoelectric coolers specifically 
designed for this temperature control are available commercially and 
normally operate in the range of 5[deg] to 15 [deg]C. Small 
refrigerators can be modified to provide the required temperature 
control; however, inlet lines must be insulated from the lower 
temperatures to prevent condensation when sampling under humid 
conditions. A small heating pad may be necessary when sampling at low 
temperatures (<7 [deg]C) to prevent the absorbing solution from 
freezing.(17)
    7.1.11 Sampling train container: The absorbing solution must be 
shielded from light during and after sampling. Most commercially 
available sampler trains are enclosed in a light-proof box.
    7.1.12 Timer: A timer is recommended to initiate and to stop 
sampling for the 24-hour period. The timer is not a required piece of 
equipment; however, without the timer a technician would be required to 
start and stop the sampling manually. An elapsed time meter is also 
recommended to determine the duration of the sampling period.
    7.2 Shipping.
    7.2.1 Shipping container: A shipping container that can maintain a 
temperature of 5[deg] 5 [deg]C is used for 
transporting the sample from the collection site to the analytical 
laboratory. Ice coolers or refrigerated shipping containers have been 
found to be satisfactory. The use of eutectic cold packs instead of ice 
will give a more stable temperature control. Such equipment is available 
from Cole-Parmer Company, 7425 North Oak Park Avenue, Chicago, IL 60648.
    7.3 Analysis.
    7.3.1 Spectrophotometer: A spectrophotometer suitable for 
measurement of absorbances at 548 nm with an effective spectral 
bandwidth of less than 15 nm is required for analysis. If the 
spectrophotometer reads out in transmittance, convert to absorbance as 
follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.000

where:

A = absorbance, and
T = transmittance (0<=T<1).

    A standard wavelength filter traceable to the National Bureau of 
Standards is used to verify the wavelength calibration according to the 
procedure enclosed with the filter. The wavelength calibration must be 
verified upon initial receipt of the instrument and after each 160 hours 
of normal use or every 6 months, whichever occurs first.
    7.3.2 Spectrophotometer cells: A set of 1-cm path length cells 
suitable for use in the visible region is used during analysis. If the 
cells are unmatched, a matching correction factor must be determined 
according to Section 10.1.
    7.3.3 Temperature control device: The color development step during 
analysis must be conducted in an environment that is in the range of 
20[deg] to 30 [deg]C and controlled to 1 [deg]C. 
Both calibration and sample analysis must be performed under identical 
conditions (within 1 [deg]C). Adequate temperature control may be 
obtained by means of constant temperature baths, water baths with manual 
temperature control, or temperature controlled rooms.
    7.3.4 Glassware: Class A volumetric glassware of various capacities 
is required for preparing and standardizing reagents and standards and 
for dispensing solutions during analysis. These included pipets, 
volumetric flasks, and burets.
    7.3.5 TCM waste receptacle: A glass waste receptacle is required for 
the storage of spent TCM solution. This vessel should be stoppered and 
stored in a hood at all times.
    8.0 Reagents.
    8.1 Sampling.

[[Page 29]]

    8.1.1 Distilled water: Purity of distilled water must be verified by 
the following procedure:(18)
 Place 0.20 mL of potassium permanganate solution 
(0.316 g/L), 500 mL of distilled water, and 1mL of concentrated sulfuric 
acid in a chemically resistant glass bottle, stopper the bottle, and 
allow to stand.
 If the permanganate color (pink) does not disappear 
completely after a period of 1 hour at room temperature, the water is 
suitable for use.
 If the permanganate color does disappear, the water 
can be purified by redistilling with one crystal each of barium 
hydroxide and potassium permanganate in an all glass still.

    8.1.2 Absorbing reagent (0.04 M potassium tetrachloromercurate 
[TCM]): Dissolve 10.86 g mercuric chloride, 0.066 g EDTA, and 6.0 g 
potassium chloride in distilled water and dilute to volume with 
distilled water in a 1,000-mL volumetric flask. (Caution: Mercuric 
chloride is highly poisonous. If spilled on skin, flush with water 
immediately.) The pH of this reagent should be between 3.0 and 5.0 (10) 
Check the pH of the absorbing solution by using pH indicating paper or a 
pH meter. If the pH of the solution is not between 3.0 and 5.0, dispose 
of the solution according to one of the disposal techniques described in 
Section 13.0. The absorbing reagent is normally stable for 6 months. If 
a precipitate forms, dispose of the reagent according to one of the 
procedures described in Section 13.0.
    8.2 Analysis.
    8.2.1 Sulfamic acid (0.6%): Dissolve 0.6 g sulfamic acid in 100 mL 
distilled water. Perpare fresh daily.
    8.2.2 Formaldehyde (0.2%): Dilute 5 mL formaldehyde solution (36 to 
38 percent) to 1,000 mL with distilled water. Prepare fresh daily.
    8.2.3 Stock iodine solution (0.1 N): Place 12.7 g resublimed iodine 
in a 250-mL beaker and add 40 g potassium iodide and 25 mL water. Stir 
until dissolved, transfer to a 1,000 mL volumetric flask and dilute to 
volume with distilled water.
    8.2.4 Iodine solution (0.01 N): Prepare approximately 0.01 N iodine 
solution by diluting 50 mL of stock iodine solution (Section 8.2.3) to 
500 mL with distilled water.
    8.2.5 Starch indicator solution: Triturate 0.4 g soluble starch and 
0.002 g mercuric iodide (preservative) with enough distilled water to 
form a paste. Add the paste slowly to 200 mL of boiling distilled water 
and continue boiling until clear. Cool and transfer the solution to a 
glass stopperd bottle.
    8.2.6 1 N hydrochloric acid: Slowly and while stirring, add 86 mL of 
concentrated hydrochloric acid to 500 mL of distilled water. Allow to 
cool and dilute to 1,000 mL with distilled water.
    8.2.7 Potassium iodate solution: Accurately weigh to the nearest 0.1 
mg, 1.5 g (record weight) of primary standard grade potassium iodate 
that has been previously dried at 180 [deg]C for at least 3 hours and 
cooled in a dessicator. Dissolve, then dilute to volume in a 500-mL 
volumetric flask with distilled water.
    8.2.8 Stock sodium thiosulfate solution (0.1 N): Prepare a stock 
solution by dissolving 25 g sodium thiosulfate (Na2 
S2 O3 / 5H2 O) in 1,000 mL freshly 
boiled, cooled, distilled water and adding 0.1 g sodium carbonate to the 
solution. Allow the solution to stand at least 1 day before 
standardizing. To standardize, accurately pipet 50 mL of potassium 
iodate solution (Section 8.2.7) into a 500-mL iodine flask and add 2.0 g 
of potassium iodide and 10 mL of 1 N HCl. Stopper the flask and allow to 
stand for 5 minutes. Titrate the solution with stock sodium thiosulfate 
solution (Section 8.2.8) to a pale yellow color. Add 5 mL of starch 
solution (Section 8.2.5) and titrate until the blue color just 
disappears. Calculate the normality (Ns) of the stock sodium 
thiosulfate solution as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.001

where:

M = volume of thiosulfate required in mL, and
W = weight of potassium iodate in g (recorded weight in Section 8.2.7).
[GRAPHIC] [TIFF OMITTED] TC08NO91.002

    8.2.9 Working sodium thiosulfate titrant (0.01 N): Accurately pipet 
100 mL of stock sodium thiosulfate solution (Section 8.2.8) into a 
1,000-mL volumetric flask and dilute to volume with freshly boiled, 
cooled, distilled water. Calculate the normality of the working sodium 
thiosulfate titrant (NT) as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.003

    8.2.10 Standardized sulfite solution for the preparation of working 
sulfite-TCM solution: Dissolve 0.30 g sodium metabisulfite 
(Na2 S2 O5) or 0.40 g sodium sulfite 
(Na2 SO3) in 500 mL of recently boiled, cooled, 
distilled water. (Sulfite solution is unstable; it is therefore 
important to use water of the highest purity to minimize this 
instability.) This solution contains the equivalent of 320 to 400 
[micro]g SO2/mL. The actual concentration of the solution is 
determined by adding excess iodine and back-titrating with standard 
sodium thiosulfate solution. To back-titrate, pipet 50 mL of the 0.01 N 
iodine solution (Section 8.2.4) into each of two 500-mL iodine flasks (A 
and B). To flask A (blank) add 25 mL distilled water, and to flask B 
(sample)

[[Page 30]]

pipet 25 mL sulfite solution. Stopper the flasks and allow to stand for 
5 minutes. Prepare the working sulfite-TCM solution (Section 8.2.11) 
immediately prior to adding the iodine solution to the flasks. Using a 
buret containing standardized 0.01 N thiosulfate titrant (Section 
8.2.9), titrate the solution in each flask to a pale yellow color. Then 
add 5 mL starch solution (Section 8.2.5) and continue the titration 
until the blue color just disappears.
    8.2.11 Working sulfite-TCM solution: Accurately pipet 5 mL of the 
standard sulfite solution (Section 8.2.10) into a 250-mL volumetric 
flask and dilute to volume with 0.04 M TCM. Calculate the concentration 
of sulfur dioxide in the working solution as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.004

where:

A = volume of thiosulfate titrant required for the blank, mL;
B = volume of thiosulfate titrant required for the sample, mL;
NT = normality of the thiosulfate titrant, from equation (3);
32,000 = milliequivalent weight of SO2, [micro]g;
25 = volume of standard sulfite solution, mL; and
0.02 = dilution factor.

    This solution is stable for 30 days if kept at 5 [deg]C. (16) If not 
kept at 5 [deg]C, prepare fresh daily.
    8.2.12 Purified pararosaniline (PRA) stock solution (0.2% nominal):
    8.2.12.1 Dye specifications--

 The dye must have a maximum absorbance at a 
wavelength of 540 nm when assayed in a buffered solution of 0.1 M sodium 
acetate-acetic acid;
 The absorbance of the reagent blank, which is 
temperature sensitive (0.015 absorbance unit/ [deg]C), must not exceed 
0.170 at 22 [deg]C with a 1-cm optical path length when the blank is 
prepared according to the specified procedure;
 The calibration curve (Section 10.0) must have a 
slope equal to 0.030 0.002 absorbance unit/
[micro]g SO2 with a 1-cm optical path length when the dye is 
pure and the sulfite solution is properly standardized.

    8.2.12.2 Preparation of stock PRA solution--A specially purified (99 
to 100 percent pure) solution of pararosaniline, which meets the above 
specifications, is commercially available in the required 0.20 percent 
concentration (Harleco Co.). Alternatively, the dye may be purified, a 
stock solution prepared, and then assayed according to the procedure as 
described below.(10)
    8.2.12.3 Purification procedure for PRA--
    1. Place 100 mL each of 1-butanol and 1 N HCl in a large separatory 
funnel (250-mL) and allow to equilibrate. Note: Certain batches of 1-
butanol contain oxidants that create an SO2 demand. Before 
using, check by placing 20 mL of 1-butanol and 5 mL of 20 percent 
potassium iodide (KI) solution in a 50-mL separatory funnel and shake 
thoroughly. If a yellow color appears in the alcohol phase, redistill 
the 1-butanol from silver oxide and collect the middle fraction or 
purchase a new supply of 1-butanol.
    2. Weigh 100 mg of pararosaniline hydrochloride dye (PRA) in a small 
beaker. Add 50 mL of the equilibrated acid (drain in acid from the 
bottom of the separatory funnel in 1.) to the beaker and let stand for 
several minutes. Discard the remaining acid phase in the separatory 
funnel.
    3. To a 125-mL separatory funnel, add 50 mL of the equilibrated 1-
butanol (draw the 1-butanol from the top of the separatory funnel in 
1.). Transfer the acid solution (from 2.) containing the dye to the 
funnel and shake carefully to extract. The violet impurity will transfer 
to the organic phase.
    4. Transfer the lower aqueous phase into another separatory funnel, 
add 20 mL of equilibrated 1-butanol, and extract again.
    5. Repeat the extraction procedure with three more 10-mL portions of 
equilibrated 1-butanol.
    6. After the final extraction, filter the acid phase through a 
cotton plug into a 50-mL volumetric flask and bring to volume with 1 N 
HCl. This stock reagent will be a yellowish red.
    7. To check the purity of the PRA, perform the assay and adjustment 
of concentration (Section 8.2.12.4) and prepare a reagent blank (Section 
11.2); the absorbance of this reagent blank at 540 nm should be less 
than 0.170 at 22 [deg]C. If the absorbance is greater than 0.170 under 
these conditions, further extractions should be performed.
    8.2.12.4 PRA assay procedure--The concentration of pararosaniline 
hydrochloride (PRA) need be assayed only once after purification. It is 
also recommended that commercial solutions of pararosaniline be assayed 
when first purchased. The assay procedure is as follows:(10)
    1. Prepare 1 M acetate-acetic acid buffer stock solution with a pH 
of 4.79 by dissolving

[[Page 31]]

13.61 g of sodium acetate trihydrate in distilled water in a 100-mL 
volumetric flask. Add 5.70 mL of glacial acetic acid and dilute to 
volume with distilled water.
    2. Pipet 1 mL of the stock PRA solution obtained from the 
purification process or from a commercial source into a 100-mL 
volumetric flask and dilute to volume with distilled water.
    3. Transfer a 5-mL aliquot of the diluted PRA solution from 2. into 
a 50-mL volumetric flask. Add 5mL of 1 M acetate-acetic acid buffer 
solution from 1. and dilute the mixture to volume with distilled water. 
Let the mixture stand for 1 hour.
    4. Measure the absorbance of the above solution at 540 nm with a 
spectrophotometer against a distilled water reference. Compute the 
percentage of nominal concentration of PRA by
[GRAPHIC] [TIFF OMITTED] TC08NO91.005

where:

A = measured absorbance of the final mixture (absorbance units);
W = weight in grams of the PRA dye used in the assay to prepare 50 mL of 
          stock solution (for example, 0.100 g of dye was used to 
          prepare 50 mL of solution in the purification procedure; when 
          obtained from commercial sources, use the stated concentration 
          to compute W; for 98% PRA, W = .098 g.); and
K = 21.3 for spectrophotometers having a spectral bandwidth of less than 
          15 nm and a path length of 1 cm.

    8.2.13 Pararosaniline reagent: To a 250-mL volumetric flask, add 20 
mL of stock PRA solution. Add an additional 0.2 mL of stock solution for 
each percentage that the stock assays below 100 percent. Then add 25 mL 
of 3 M phosphoric acid and dilute to volume with distilled water. The 
reagent is stable for at least 9 months. Store away from heat and light.
    9.0 Sampling Procedure.
    9.1 General Considerations. Procedures are described for short-term 
sampling (30-minute and 1-hour) and for long-term sampling (24-hour). 
Different combinations of absorbing reagent volume, sampling rate, and 
sampling time can be selected to meet special needs. For combinations 
other than those specifically described, the conditions must be adjusted 
so that linearity is maintained between absorbance and concentration 
over the dynamic range. Absorbing reagent volumes less than 10 mL are 
not recommended. The collection efficiency is above 98 percent for the 
conditions described; however, the efficiency may be substantially lower 
when sampling concentrations below 25 [micro][gamma]SO2/
m\3\.(8,9)
    9.2 30-Minute and 1-Hour Sampling. Place 10 mL of TCM absorbing 
reagent in a midget impinger and seal the impinger with a thin film of 
silicon stopcock grease (around the ground glass joint). Insert the 
sealed impinger into the sampling train as shown in Figure 1, making 
sure that all connections between the various components are leak tight. 
Greaseless ball joint fittings, heat shrinkable Teflon [supreg] tubing, 
or Teflon [supreg] tube fittings may be used to attain leakfree 
conditions for portions of the sampling train that come into contact 
with air containing SO2. Shield the absorbing reagent from 
direct sunlight by covering the impinger with aluminum foil or by 
enclosing the sampling train in a light-proof box. Determine the flow 
rate according to Section 9.4.2. Collect the sample at 1 0.10 L/min for 30-minute sampling or 0.500 0.05 L/min for 1-hour sampling. Record the exact 
sampling time in minutes, as the sample volume will later be determined 
using the sampling flow rate and the sampling time. Record the 
atmospheric pressure and temperature.
    9.3 24-Hour Sampling. Place 50 mL of TCM absorbing solution in a 
large absorber, close the cap, and, if needed, apply the heat shrink 
material as shown in Figure 3. Verify that the reagent level is at the 
50 mL mark on the absorber. Insert the sealed absorber into the sampling 
train as shown in Figure 2. At this time verify that the absorber 
temperature is controlled to 15 10 [deg]C. During 
sampling, the absorber temperature must be controlled to prevent 
decomposition of the collected complex. From the onset of sampling until 
analysis, the absorbing solution must be protected from direct sunlight. 
Determine the flow rate according to Section 9.4.2. Collect the sample 
for 24 hours from midnight to midnight at a flow rate of 0.200 0.020 L/min. A start/stop timer is helpful for 
initiating and stopping sampling and an elapsed time meter will be 
useful for determining the sampling time.

[[Page 32]]



    9.4 Flow Measurement.
    9.4.1 Calibration: Flow measuring devices used for the on-site flow 
measurements required in 9.4.2 must be calibrated against a reliable 
flow or volume standard such as an NBS traceable bubble flowmeter or 
calibrated wet test meter. Rotameters or critical orifices used in the 
sampling train may be calibrated, if desired, as a quality control 
check, but such calibration shall not replace the on-site flow 
measurements required by 9.4.2. In-line rotameters, if they are to be 
calibrated, should be calibrated in situ, with the appropriate volume of 
solution in the absorber.
    9.4.2 Determination of flow rate at sampling site: For short-term 
samples, the standard flow rate is determined at the sampling site at 
the initiation and completion of sample collection with a calibrated 
flow measuring device connected to the inlet of the absorber. For 24-
hour samples, the standard flow rate is determined at the time the 
absorber is placed in the sampling train and again when the absorber is 
removed from the train for shipment to the analytical laboratory with a 
calibrated flow measuring device connected to the inlet of the sampling 
train. The flow rate determination must be made with all components of 
the sampling system in operation (e.g., the absorber temperature 
controller and any sample box heaters must also be operating). Equation 
6 may be used to determine the standard flow rate when a calibrated 
positive displacement meter is used as the flow measuring device. Other 
types of calibrated flow measuring devices may also be used to determine 
the flow rate at the sampling site provided that the user applies any 
appropriate corrections to devices for which output is dependent on 
temperature or pressure.

[[Page 33]]

[GRAPHIC] [TIFF OMITTED] TC08NO91.006

where:

Qstd = flow rate at standard conditions, std L/min (25 [deg]C 
          and 760 mm Hg);
Qact = flow rate at monitoring site conditions, L/min;
Pb = barometric pressure at monitoring site conditions, mm Hg 
          or kPa;
RH = fractional relative humidity of the air being measured;
PH2O = vapor pressure of water at the temperature 
          of the air in the flow or volume standard, in the same units 
          as Pb, (for wet volume standards only, i.e., bubble 
          flowmeter or wet test meter; for dry standards, i.e., dry test 
          meter, PH2O = 0);
Pstd = standard barometric pressure, in the same units as 
          Pb (760 mm Hg or 101 kPa); and
Tmeter = temperature of the air in the flow or volume 
          standard, [deg]C (e.g., bubble flowmeter).

    If a barometer is not available, the following equation may be used 
to determine the barometric pressure:
[GRAPHIC] [TIFF OMITTED] TC08NO91.007

where:

H = sampling site elevation above sea level in meters.

    If the initial flow rate (Qi) differs from the flow rate 
of the critical orifice or the flow rate indicated by the flowmeter in 
the sampling train (Qc) by more than 5 percent as determined 
by equation (8), check for leaks and redetermine Qi.
[GRAPHIC] [TIFF OMITTED] TC08NO91.008

    Invalidate the sample if the difference between the initial 
(Qi) and final (Qf) flow rates is more than 5 
percent as determined by equation (9):
[GRAPHIC] [TIFF OMITTED] TC08NO91.009

    9.5 Sample Storage and Shipment. Remove the impinger or absorber 
from the sampling train and stopper immediately. Verify that the 
temperature of the absorber is not above 25 [deg]C. Mark the level of 
the solution with a temporary (e.g., grease pencil) mark. If the sample 
will not be analyzed within 12 hours of sampling, it must be stored at 
5[deg] 5 [deg]C until analysis. Analysis must 
occur within 30 days. If the sample is transported or shipped for a 
period exceeding 12 hours, it is recommended that thermal coolers using 
eutectic ice packs, refrigerated shipping containers, etc., be used for 
periods up to 48 hours. (17) Measure the temperature of the absorber 
solution when the shipment is received. Invalidate the sample if the 
temperature is above 10 [deg]C. Store the sample at 5[deg] 5 [deg]C until it is analyzed.
    10.0 Analytical Calibration.
    10.1 Spectrophotometer Cell Matching. If unmatched spectrophotometer 
cells are used, an absorbance correction factor must be determined as 
follows:
    1. Fill all cells with distilled water and designate the one that 
has the lowest absorbance at 548 nm as the reference. (This reference 
cell should be marked as such and continually used for this purpose 
throughout all future analyses.)
    2. Zero the spectrophotometer with the reference cell.
    3. Determine the absorbance of the remaining cells (Ac) 
in relation to the reference cell and record these values for future 
use. Mark all cells in a manner that adequately identifies the 
correction.
    The corrected absorbance during future analyses using each cell is 
determining as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.010

where:

A = corrected absorbance,
Aobs = uncorrected absorbance, and
Ac = cell correction.

    10.2 Static Calibration Procedure (Option 1). Prepare a dilute 
working sulfite-TCM solution by diluting 10 mL of the working sulfite-
TCM solution (Section 8.2.11) to 100 mL with TCM absorbing reagent. 
Following the table below, accurately pipet the indicated volumes of the 
sulfite-TCM solutions into a series of 25-mL volumetric flasks. Add TCM 
absorbing reagent as indicated to bring the volume in each flask to 10 
mL.

[[Page 34]]



------------------------------------------------------------------------
                                        Volume of                Total
                                         sulfite-  Volume of   [micro]g
         Sulfite-TCM solution              TCM      TCM, mL       SO2
                                         solution             (approx.)*
------------------------------------------------------------------------
Working...............................        4.0        6.0        28.8
Working...............................        3.0        7.0        21.6
Working...............................        2.0        8.0        14.4
Dilute working........................       10.0        0.0         7.2
Dilute working........................        5.0        5.0         3.6
                                              0.0       10.0         0.0
------------------------------------------------------------------------
*Based on working sulfite-TCM solution concentration of 7.2 [micro]g SO2/
  mL; the actual total [micro]g SO2 must be calculated using equation 11
  below.

    To each volumetric flask, add 1 mL 0.6% sulfamic acid (Section 
8.2.1), accurately pipet 2 mL 0.2% formaldehyde solution (Section 
8.2.2), then add 5 mL pararosaniline solution (Section 8.2.13). Start a 
laboratory timer that has been set for 30 minutes. Bring all flasks to 
volume with recently boiled and cooled distilled water and mix 
thoroughly. The color must be developed (during the 30-minute period) in 
a temperature environment in the range of 20[deg] to 30 [deg]C, which is 
controlled to 1 [deg]C. For increased precision, a 
constant temperature bath is recommended during the color development 
step. After 30 minutes, determine the corrected absorbance of each 
standard at 548 nm against a distilled water reference (Section 10.1). 
Denote this absorbance as (A). Distilled water is used in the reference 
cell rather than the reagant blank because of the temperature 
sensitivity of the reagent blank. Calculate the total micrograms 
SO2 in each solution:
[GRAPHIC] [TIFF OMITTED] TC08NO91.011

where:

VTCM/SO2 = volume of sulfite-TCM solution used, mL;
CTCM/SO2 = concentration of sulfur dioxide in the working 
          sulfite-TCM, [micro]g SO2/mL (from equation 4); and
D = dilution factor (D = 1 for the working sulfite-TCM solution; D = 0.1 
          for the diluted working sulfite-TCM solution).

    A calibration equation is determined using the method of linear 
least squares (Section 12.1). The total micrograms SO2 
contained in each solution is the x variable, and the corrected 
absorbance (eq. 10) associated with each solution is the y variable. For 
the calibration to be valid, the slope must be in the range of 0.030 
0.002 absorbance unit/[micro]g SO2, the 
intercept as determined by the least squares method must be equal to or 
less than 0.170 absorbance unit when the color is developed at 22 [deg]C 
(add 0.015 to this 0.170 specification for each [deg]C above 22 [deg]C) 
and the correlation coefficient must be greater than 0.998. If these 
criteria are not met, it may be the result of an impure dye and/or an 
improperly standardized sulfite-TCM solution. A calibration factor 
(Bs) is determined by calculating the reciprocal of the slope 
and is subsequently used for calculating the sample concentration 
(Section 12.3).
    10.3 Dynamic Calibration Procedures (Option 2). Atmospheres 
containing accurately known concentrations of sulfur dioxide are 
prepared using permeation devices. In the systems for generating these 
atmospheres, the permeation device emits gaseous SO2 at a 
known, low, constant rate, provided the temperature of the device is 
held constant (0.1 [deg]C) and the device has been 
accurately calibrated at the temperature of use. The SO2 
permeating from the device is carried by a low flow of dry carrier gas 
to a mixing chamber where it is diluted with SO2-free air to 
the desired concentration and supplied to a vented manifold. A typical 
system is shown schematically in Figure 4 and this system and other 
similar systems have been described in detail by O'Keeffe and Ortman; 
(19) Scaringelli, Frey, and Saltzman, (20) and Scaringelli, O'Keeffe, 
Rosenberg, and Bell. (21) Permeation devices may be prepared or 
purchased and in both cases must be traceable either to a National 
Bureau of Standards (NBS) Standard Reference Material (SRM 1625, SRM 
1626, SRM 1627) or to an NBS/EPA-approved commercially available 
Certified Reference Material (CRM). CRM's are described in Reference 22, 
and a list of CRM sources is available from the address shown for 
Reference 22. A recommended protocol for certifying a permeation device 
to an NBS SRM or CRM is given in Section 2.0.7 of Reference 2. Device 
permeation rates of 0.2 to 0.4 [micro]g/min, inert gas flows of about 50 
mL/min, and dilution air flow rates from 1.1 to 15 L/min conveniently 
yield standard atmospheres in the range of 25 to 600 [micro]g 
SO2/m\3\ (0.010 to 0.230 ppm).
    10.3.1 Calibration Option 2A (30-minute and 1-hour samples): 
Generate a series of six standard atmospheres of SO2 (e.g., 
0, 50, 100, 200, 350, 500, 750 [micro]g/m\3\) by adjusting the dilution 
flow rates appropriately. The concentration of SO2 in each 
atmosphere is calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.014

where:


[[Page 35]]


Ca = concentration of SO2 at standard conditions, 
          [micro]g/m\3\;
Pr = permeation rate, [micro]g/min;
Qd = flow rate of dilution air, std L/min; and
Qp = flow rate of carrier gas across permeation device, std 
          L/min.
          
          

[[Page 36]]


    Be sure that the total flow rate of the standard exceeds the flow 
demand of the sample train, with the excess flow vented at atmospheric 
pressure. Sample each atmosphere using similar apparatus as shown in 
Figure 1 and under the same conditions as field sampling (i.e., use same 
absorbing reagent volume and sample same volume of air at an equivalent 
flow rate). Due to the length of the sampling periods required, this 
method is not recommended for 24-hour sampling. At the completion of 
sampling, quantitatively transfer the contents of each impinger to one 
of a series of 25-mL volumetric flasks (if 10 mL of absorbing solution 
was used) using small amounts of distilled water for rinse (<5mL). If 
10 mL of absorbing solution was used, bring the absorber 
solution in each impinger to orginal volume with distilled H2 
O and pipet 10-mL portions from each impinger into a series of 25-mL 
volumetric flasks. If the color development steps are not to be started 
within 12 hours of sampling, store the solutions at 5[deg] 5 [deg]C. Calculate the total micrograms SO2 
in each solution as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.015

where:

Ca = concentration of SO2 in the standard 
          atmosphere, [micro]g/m\3\;
Os = sampling flow rate, std L/min;
t = sampling time, min;
Va = volume of absorbing solution used for color development 
          (10 mL); and
Vb = volume of absorbing solution used for sampling, mL.

    Add the remaining reagents for color development in the same manner 
as in Section 10.2 for static solutions. Calculate a calibration 
equation and a calibration factor (Bg) according to Section 
10.2, adhering to all the specified criteria.
    10.3.2 Calibration Option 2B (24-hour samples): Generate a standard 
atmosphere containing approximately 1,050 [micro]g SO2/m\3\ 
and calculate the exact concentration according to equation 12. Set up a 
series of six absorbers according to Figure 2 and connect to a common 
manifold for sampling the standard atmosphere. Be sure that the total 
flow rate of the standard exceeds the flow demand at the sample 
manifold, with the excess flow vented at atmospheric pressure. The 
absorbers are then allowed to sample the atmosphere for varying time 
periods to yield solutions containing 0, 0.2, 0.6, 1.0, 1.4, 1.8, and 
2.2 [micro]g SO2/mL solution. The sampling times required to 
attain these solution concentrations are calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.016

where:

t = sampling time, min;
Vb = volume of absorbing solution used for sampling (50 mL);
Cs = desired concentration of SO2 in the absorbing 
          solution, [micro]g/mL;
Ca = concentration of the standard atmosphere calculated 
          according to equation 12, [micro]g/m\3\; and
Qs = sampling flow rate, std L/min.

    At the completion of sampling, bring the absorber solutions to 
original volume with distilled water. Pipet a 10-mL portion from each 
absorber into one of a series of 25-mL volumetric flasks. If the color 
development steps are not to be started within 12 hours of sampling, 
store the solutions at 5[deg] 5 [deg]C. Add the 
remaining reagents for color development in the same manner as in 
Section 10.2 for static solutions. Calculate the total [micro]g 
SO2 in each standard as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.017

where:

Va = volume of absorbing solution used for color development 
          (10 mL).
All other parameters are defined in equation 14.

    Calculate a calibration equation and a calibration factor 
(Bt) according to Section 10.2 adhering to all the specified 
criteria.
    11.0 Sample Preparation and Analysis.
    11.1 Sample Preparation. Remove the samples from the shipping 
container. If the shipment period exceeded 12 hours from the completion 
of sampling, verify that the temperature is below 10 [deg]C. Also, 
compare the solution level to the temporary level mark on the absorber. 
If either the temperature is above 10 [deg]C or there was significant 
loss (more than 10 mL) of the sample during shipping, make an 
appropriate notation in the record and invalidate the sample. Prepare 
the samples for analysis as follows:
    1. For 30-minute or 1-hour samples: Quantitatively transfer the 
entire 10 mL amount of absorbing solution to a 25-mL volumetric flask 
and rinse with a small amount (<5 mL) of distilled water.
    2. For 24-hour samples: If the volume of the sample is less than the 
original 50-mL volume (permanent mark on the absorber), adjust the 
volume back to the original volume with distilled water to compensate 
for water lost to evaporation during sampling. If the final volume is 
greater than the original volume, the volume must be measured using a 
graduated cylinder. To analyze, pipet 10 mL

[[Page 37]]

of the solution into a 25-mL volumetric flask.
    11.2 Sample Analysis. For each set of determinations, prepare a 
reagent blank by adding 10 mL TCM absorbing solution to a 25-mL 
volumetric flask, and two control standards containing approximately 5 
and 15 [micro]g SO2, respectively. The control standards are 
prepared according to Section 10.2 or 10.3. The analysis is carried out 
as follows:
    1. Allow the sample to stand 20 minutes after the completion of 
sampling to allow any ozone to decompose (if applicable).
    2. To each 25-mL volumetric flask containing reagent blank, sample, 
or control standard, add 1 mL of 0.6% sulfamic acid (Section 8.2.1) and 
allow to react for 10 min.
    3. Accurately pipet 2 mL of 0.2% formaldehyde solution (Section 
8.2.2) and then 5 mL of pararosaniline solution (Section 8.2.13) into 
each flask. Start a laboratory timer set at 30 minutes.
    4. Bring each flask to volume with recently boiled and cooled 
distilled water and mix thoroughly.
    5. During the 30 minutes, the solutions must be in a temperature 
controlled environment in the range of 20[deg] to 30 [deg]C maintained 
to 1 [deg]C. This temperature must also be within 
1 [deg]C of that used during calibration.
    6. After 30 minutes and before 60 minutes, determine the corrected 
absorbances (equation 10) of each solution at 548 nm using 1-cm optical 
path length cells against a distilled water reference (Section 10.1). 
(Distilled water is used as a reference instead of the reagent blank 
because of the sensitivity of the reagent blank to temperature.)
    7. Do not allow the colored solution to stand in the cells because a 
film may be deposited. Clean the cells with isopropyl alcohol after use.
    8. The reagent blank must be within 0.03 absorbance units of the 
intercept of the calibration equation determined in Section 10.
    11.3 Absorbance range. If the absorbance of the sample solution 
ranges between 1.0 and 2.0, the sample can be diluted 1:1 with a portion 
of the reagent blank and the absorbance redetermined within 5 minutes. 
Solutions with higher absorbances can be diluted up to sixfold with the 
reagent blank in order to obtain scale readings of less than 1.0 
absorbance unit. However, it is recommended that a smaller portion (<10 
mL) of the original sample be reanalyzed (if possible) if the sample 
requires a dilution greater than 1:1.
    11.4 Reagent disposal. All reagents containing mercury compounds 
must be stored and disposed of using one of the procedures contained in 
Section 13. Until disposal, the discarded solutions can be stored in 
closed glass containers and should be left in a fume hood.
    12.0 Calculations.
    12.1 Calibration Slope, Intercept, and Correlation Coefficient. The 
method of least squares is used to calculate a calibration equation in 
the form of:
[GRAPHIC] [TIFF OMITTED] TC08NO91.012

where:

y = corrected absorbance,
m = slope, absorbance unit/[micro]g SO2,
x = micrograms of SO2,
b = y intercept (absorbance units).

    The slope (m), intercept (b), and correlation coefficient (r) are 
calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.018

[GRAPHIC] [TIFF OMITTED] TR31AU93.019

[GRAPHIC] [TIFF OMITTED] TR31AU93.020

where n is the number of calibration points.
    A data form (Figure 5) is supplied for easily organizing calibration 
data when the slope, intercept, and correlation coefficient are 
calculated by hand.
    12.2 Total Sample Volume. Determine the sampling volume at standard 
conditions as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.021

where:

Vstd = sampling volume in std L,
Qi = standard flow rate determined at the initiation of 
          sampling in std L/min,
Qf = standard flow rate determined at the completion of 
          sampling is std L/min, and
t = total sampling time, min.

    12.3 Sulfur Dioxide Concentration. Calculate and report the 
concentration of each sample as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.022

where:

A = corrected absorbance of the sample solution, from equation (10);
Ao = corrected absorbance of the reagent blank, using 
          equation (10);
BX = calibration factor equal to Bs, 
          Bg, or Bt depending on the calibration 
          procedure used, the reciprocal of the slope of the calibration 
          equation;
Va = volume of absorber solution analyzed, mL;
Vb = total volume of solution in absorber (see 11.1-2), mL; 
          and
Vstd = standard air volume sampled, std L (from Section 
          12.2).

[[Page 38]]



                                                    Data Form
                                             [For hand calculations]
----------------------------------------------------------------------------------------------------------------
                                                      Absor- bance
     Calibration point no.       Micro- grams So2        units
----------------------------------------------------------------------------------------------------------------
                                       (x)                (y)                x\2\               xy          y\2\
1.............................  .................  .................  .................  ................  .....
2.............................  .................  .................  .................  ................  .....
3.............................  .................  .................  .................  ................  .....
4.............................  .................  .................  .................  ................  .....
5.............................  .................  .................  .................  ................  .....
6.............................  .................  .................  .................  ................  .....
----------------------------------------------------------------------------------------------------------------

[Sigma] x=___ [Sigma] y=___ [Sigma] x\2\=___ [Sigma]xy___ [Sigma]y\2\___
n=___ (number of pairs of coordinates.)
________________________________________________________________________

Figure 5. Data form for hand calculations.

    12.4 Control Standards. Calculate the analyzed micrograms of 
SO2 in each control standard as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.070

where:

Cq = analyzed [micro]g SO2 in each control 
          standard,
A = corrected absorbance of the control standard, and
Ao = corrected absorbance of the reagent blank.

    The difference between the true and analyzed values of the control 
standards must not be greater than 1 [micro]g. If the difference is 
greater than 1 [micro]g, the source of the discrepancy must be 
identified and corrected.
    12.5 Conversion of [micro]g/m\3\ to ppm (v/v). If desired, the 
concentration of sulfur dioxide at reference conditions can be converted 
to ppm SO2 (v/v) as follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.023

    13.0 The TCM absorbing solution and any reagents containing mercury 
compounds must be treated and disposed of by one of the methods 
discussed below. Both methods remove greater than 99.99 percent of the 
mercury.
    13.1 Disposal of Mercury-Containing Solutions.
    13.2 Method for Forming an Amalgam.
    1. Place the waste solution in an uncapped vessel in a hood.
    2. For each liter of waste solution, add approximately 10 g of 
sodium carbonate until neutralization has occurred (NaOH may have to be 
used).
    3. Following neutralization, add 10 g of granular zinc or magnesium.
    4. Stir the solution in a hood for 24 hours. Caution must be 
exercised as hydrogen gas is evolved by this treatment process.
    5. After 24 hours, allow the solution to stand without stirring to 
allow the mercury amalgam (solid black material) to settle to the bottom 
of the waste receptacle.
    6. Upon settling, decant and discard the supernatant liquid.
    7. Quantitatively transfer the solid material to a container and 
allow to dry.
    8. The solid material can be sent to a mercury reclaiming plant. It 
must not be discarded.
    13.3 Method Using Aluminum Foil Strips.
    1. Place the waste solution in an uncapped vessel in a hood.
    2. For each liter of waste solution, add approximately 10 g of 
aluminum foil strips. If all the aluminum is consumed and no gas is 
evolved, add an additional 10 g of foil. Repeat until the foil is no 
longer consumed and allow the gas to evolve for 24 hours.
    3. Decant the supernatant liquid and discard.
    4. Transfer the elemental mercury that has settled to the bottom of 
the vessel to a storage container.
    5. The mercury can be sent to a mercury reclaiming plant. It must 
not be discarded.
    14.0 References for SO2 Method.
    1. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume I, Principles. EPA-600/9-76-005, U.S. Environmental Protection 
Agency, Research Triangle Park, NC 27711, 1976.
    2. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume II, Ambient Air Specific Methods. EPA-600/4-77-027a, U.S. 
Environmental Protection Agency, Research Triangle Park, NC 27711, 1977.
    3. Dasqupta, P. K., and K. B. DeCesare. Stability of Sulfur Dioxide 
in Formaldehyde and Its Anomalous Behavior in Tetrachloromercurate (II). 
Submitted for publication in Atmospheric Environment, 1982.
    4. West, P. W., and G. C. Gaeke. Fixation of Sulfur Dioxide as 
Disulfitomercurate (II) and Subsequent Colorimetric Estimation. Anal. 
Chem., 28:1816, 1956.
    5. Ephraim, F. Inorganic Chemistry. P. C. L. Thorne and E. R. 
Roberts, Eds., 5th Edition, Interscience, 1948, p. 562.
    6. Lyles, G. R., F. B. Dowling, and V. J. Blanchard. Quantitative 
Determination of Formaldehyde in the Parts Per Hundred Million 
Concentration Level. J. Air. Poll. Cont. Assoc., Vol. 15(106), 1965.
    7. McKee, H. C., R. E. Childers, and O. Saenz, Jr. Collaborative 
Study of Reference Method for Determination of Sulfur Dioxide in the 
Atmosphere (Pararosaniline Method). EPA-APTD-0903, U.S. Environmental 
Protection Agency, Research Triangle Park, NC 27711, September 1971.
    8. Urone, P., J. B. Evans, and C. M. Noyes. Tracer Techniques in 
Sulfur--Air Pollution Studies Apparatus and Studies of Sulfur Dioxide 
Colorimetric and Conductometric Methods. Anal. Chem., 37: 1104, 1965.

[[Page 39]]

    9. Bostrom, C. E. The Absorption of Sulfur Dioxide at Low 
Concentrations (pphm) Studied by an Isotopic Tracer Method. Intern. J. 
Air Water Poll., 9:333, 1965.
    10. Scaringelli, F. P., B. E. Saltzman, and S. A. Frey. 
Spectrophotometric Determination of Atmospheric Sulfur Dioxide. Anal. 
Chem., 39: 1709, 1967.
    11. Pate, J. B., B. E. Ammons, G. A. Swanson, and J. P. Lodge, Jr. 
Nitrite Interference in Spectrophotometric Determination of Atmospheric 
Sulfur Dioxide. Anal. Chem., 37:942, 1965.
    12. Zurlo, N., and A. M. Griffini. Measurement of the Sulfur Dioxide 
Content of the Air in the Presence of Oxides of Nitrogen and Heavy 
Metals. Medicina Lavoro, 53:330, 1962.
    13. Rehme, K. A., and F. P. Scaringelli. Effect of Ammonia on the 
Spectrophotometric Determination of Atmospheric Concentrations of Sulfur 
Dioxide. Anal. Chem., 47:2474, 1975.
    14. McCoy, R. A., D. E. Camann, and H. C. McKee. Collaborative Study 
of Reference Method for Determination of Sulfur Dioxide in the 
Atmosphere (Pararosaniline Method) (24-Hour Sampling). EPA-650/4-74-027, 
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, 
December 1973.
    15. Fuerst, R. G. Improved Temperature Stability of Sulfur Dioxide 
Samples Collected by the Federal Reference Method. EPA-600/4-78-018, 
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, 
April 1978.
    16. Scaringelli, F. P., L. Elfers, D. Norris, and S. Hochheiser. 
Enhanced Stability of Sulfur Dioxide in Solution. Anal. Chem., 42:1818, 
1970.
    17. Martin, B. E. Sulfur Dioxide Bubbler Temperature Study. EPA-600/
4-77-040, U.S. Environmental Protection Agency, Research Triangle Park, 
NC 27711, August 1977.
    18. American Society for Testing and Materials. ASTM Standards, 
Water; Atmospheric Analysis. Part 23. Philadelphia, PA, October 1968, p. 
226.
    19. O'Keeffe, A. E., and G. C. Ortman. Primary Standards for Trace 
Gas Analysis. Anal. Chem., 38:760, 1966.
    20. Scaringelli, F. P., S. A. Frey, and B. E. Saltzman. Evaluation 
of Teflon Permeation Tubes for Use with Sulfur Dioxide. Amer. Ind. 
Hygiene Assoc. J., 28:260, 1967.
    21. Scaringelli, F. P., A. E. O'Keeffe, E. Rosenberg, and J. P. 
Bell, Preparation of Known Concentrations of Gases and Vapors With 
Permeation Devices Calibrated Gravimetrically. Anal. Chem., 42:871, 
1970.
    22. A Procedure for Establishing Traceability of Gas Mixtures to 
Certain National Bureau of Standards Standard Reference Materials. EPA-
600/7-81-010, U.S. Environmental Protection Agency, Environmental 
Monitoring Systems Laboratory (MD-77), Research Triangle Park, NC 27711, 
January 1981.

[47 FR 54899, Dec. 6, 1982; 48 FR 17355, Apr. 22, 1983. Redesignated at 
75 FR 35595, June 22, 2010]



 Sec. Appendix B to Part 50--Reference Method for the Determination of 
   Suspended Particulate Matter in the Atmosphere (High-Volume Method)

    1.0 Applicability.
    1.1 This method provides a measurement of the mass concentration of 
total suspended particulate matter (TSP) in ambient air for determining 
compliance with the primary and secondary national ambient air quality 
standards for particulate matter as specified in Sec. 50.6 and Sec. 
50.7 of this chapter. The measurement process is nondestructive, and the 
size of the sample collected is usually adequate for subsequent chemical 
analysis. Quality assurance procedures and guidance are provided in part 
58, appendixes A and B, of this chapter and in References 1 and 2.
    2.0 Principle.
    2.1 An air sampler, properly located at the measurement site, draws 
a measured quantity of ambient air into a covered housing and through a 
filter during a 24-hr (nominal) sampling period. The sampler flow rate 
and the geometry of the shelter favor the collection of particles up to 
25-50 [micro]m (aerodynamic diameter), depending on wind speed and 
direction.(3) The filters used are specified to have a minimum 
collection efficiency of 99 percent for 0.3 [micro]m (DOP) particles 
(see Section 7.1.4).
    2.2 The filter is weighed (after moisture equilibration) before and 
after use to determine the net weight (mass) gain. The total volume of 
air sampled, corrected to EPA standard conditions (25 [deg]C, 760 mm Hg 
[101 kPa]), is determined from the measured flow rate and the sampling 
time. The concentration of total suspended particulate matter in the 
ambient air is computed as the mass of collected particles divided by 
the volume of air sampled, corrected to standard conditions, and is 
expressed in micrograms per standard cubic meter ([micro]g/std m\3\). 
For samples collected at temperatures and pressures significantly 
different than standard conditions, these corrected concentrations may 
differ substantially from actual concentrations (micrograms per actual 
cubic meter), particularly at high elevations. The actual particulate 
matter concentration can be calculated from the corrected concentration 
using the actual temperature and pressure during the sampling period.
    3.0 Range.
    3.1 The approximate concentration range of the method is 2 to 750 
[micro]g/std m\3\. The upper limit is determined by the point at which 
the

[[Page 40]]

sampler can no longer maintain the specified flow rate due to the 
increased pressure drop of the loaded filter. This point is affected by 
particle size distribution, moisture content of the collected particles, 
and variability from filter to filter, among other things. The lower 
limit is determined by the sensitivity of the balance (see Section 7.10) 
and by inherent sources of error (see Section 6).
    3.2 At wind speeds between 1.3 and 4.5 m/sec (3 and 10 mph), the 
high-volume air sampler has been found to collect particles up to 25 to 
50 [micro]m, depending on wind speed and direction.(3) For the filter 
specified in Section 7.1, there is effectively no lower limit on the 
particle size collected.
    4.0 Precision.
    4.1 Based upon collaborative testing, the relative standard 
deviation (coefficient of variation) for single analyst precision 
(repeatability) of the method is 3.0 percent. The corresponding value 
for interlaboratory precision (reproducibility) is 3.7 percent.(4)
    5.0 Accuracy.
    5.1 The absolute accuracy of the method is undefined because of the 
complex nature of atmospheric particulate matter and the difficulty in 
determining the ``true'' particulate matter concentration. This method 
provides a measure of particulate matter concentration suitable for the 
purpose specified under Section 1.0, Applicability.
    6.0 Inherent Sources of Error.
    6.1 Airflow variation. The weight of material collected on the 
filter represents the (integrated) sum of the product of the 
instantaneous flow rate times the instantaneous particle concentration. 
Therefore, dividing this weight by the average flow rate over the 
sampling period yields the true particulate matter concentration only 
when the flow rate is constant over the period. The error resulting from 
a nonconstant flow rate depends on the magnitude of the instantaneous 
changes in the flow rate and in the particulate matter concentration. 
Normally, such errors are not large, but they can be greatly reduced by 
equipping the sampler with an automatic flow controlling mechanism that 
maintains constant flow during the sampling period. Use of a contant 
flow controller is recommended.*
---------------------------------------------------------------------------

    *At elevated altitudes, the effectiveness of automatic flow 
controllers may be reduced because of a reduction in the maximum sampler 
flow.
---------------------------------------------------------------------------

    6.2 Air volume measurement. If the flow rate changes substantially 
or nonuniformly during the sampling period, appreciable error in the 
estimated air volume may result from using the average of the 
presampling and postsampling flow rates. Greater air volume measurement 
accuracy may be achieved by (1) equipping the sampler with a flow 
controlling mechanism that maintains constant air flow during the 
sampling period,* (2) using a calibrated, continuous flow rate recording 
device to record the actual flow rate during the samping period and 
integrating the flow rate over the period, or (3) any other means that 
will accurately measure the total air volume sampled during the sampling 
period. Use of a continuous flow recorder is recommended, particularly 
if the sampler is not equipped with a constant flow controller.
    6.3 Loss of volatiles. Volatile particles collected on the filter 
may be lost during subsequent sampling or during shipment and/or storage 
of the filter prior to the postsampling weighing.(5) Although such 
losses are largely unavoidable, the filter should be reweighed as soon 
after sampling as practical.
    6.4 Artifact particulate matter. Artifact particulate matter can be 
formed on the surface of alkaline glass fiber filters by oxidation of 
acid gases in the sample air, resulting in a higher than true TSP 
determination.(6 7) This effect usually occurs early in the sample 
period and is a function of the filter pH and the presence of acid 
gases. It is generally believed to account for only a small percentage 
of the filter weight gain, but the effect may become more significant 
where relatively small particulate weights are collected.
    6.5 Humidity. Glass fiber filters are comparatively insensitive to 
changes in relative humidity, but collected particulate matter can be 
hygroscopic.(8) The moisture conditioning procedure minimizes but may 
not completely eliminate error due to moisture.
    6.6 Filter handling. Careful handling of the filter between the 
presampling and postsampling weighings is necessary to avoid errors due 
to loss of fibers or particles from the filter. A filter paper cartridge 
or cassette used to protect the filter can minimize handling errors. 
(See Reference 2, Section 2).
    6.7 Nonsampled particulate matter. Particulate matter may be 
deposited on the filter by wind during periods when the sampler is 
inoperative. (9) It is recommended that errors from this source be 
minimized by an automatic mechanical device that keeps the filter 
covered during nonsampling periods, or by timely installation and 
retrieval of filters to minimize the nonsampling periods prior to and 
following operation.
    6.8 Timing errors. Samplers are normally controlled by clock timers 
set to start and stop the sampler at midnight. Errors in the nominal 
1,440-min sampling period may result from a power interruption during 
the sampling period or from a discrepancy between the start or stop time 
recorded on the filter information record and the actual start or stop 
time of the sampler. Such discrepancies may be caused by (1) poor 
resolution of the timer set-points, (2) timer error due to power 
interruption, (3) missetting of

[[Page 41]]

the timer, or (4) timer malfunction. In general, digital electronic 
timers have much better set-point resolution than mechanical timers, but 
require a battery backup system to maintain continuity of operation 
after a power interruption. A continuous flow recorder or elapsed time 
meter provides an indication of the sampler run-time, as well as 
indication of any power interruption during the sampling period and is 
therefore recommended.
    6.9 Recirculation of sampler exhaust. Under stagnant wind 
conditions, sampler exhaust air can be resampled. This effect does not 
appear to affect the TSP measurement substantially, but may result in 
increased carbon and copper in the collected sample. (10) This problem 
can be reduced by ducting the exhaust air well away, preferably 
downwind, from the sampler.
    7.0 Apparatus.
    (See References 1 and 2 for quality assurance information.)

    Note: Samplers purchased prior to the effective date of this 
amendment are not subject to specifications preceded by ([dagger]).

    7.1 Filter. (Filters supplied by the Environmental Protection Agency 
can be assumed to meet the following criteria. Additional specifications 
are required if the sample is to be analyzed chemically.)
    7.1.1 Size: 20.3 0.2 x 25.4 0.2 cm (nominal 8 x 10 in).
    7.1.2 Nominal exposed area: 406.5 cm\2\ (63 in\2\).
    7.1.3. Material: Glass fiber or other relatively inert, 
nonhygroscopic material. (8)
    7.1.4 Collection efficiency: 99 percent minimum as measured by the 
DOP test (ASTM-2986) for particles of 0.3 [micro]m diameter.
    7.1.5 Recommended pressure drop range: 42-54 mm Hg (5.6-7.2 kPa) at 
a flow rate of 1.5 std m\3\/min through the nominal exposed area.
    7.1.6 pH: 6 to 10. (11)
    7.1.7 Integrity: 2.4 mg maximum weight loss. (11)
    7.1.8 Pinholes: None.
    7.1.9 Tear strength: 500 g minimum for 20 mm wide strip cut from 
filter in weakest dimension. (See ASTM Test D828-60).
    7.1.10 Brittleness: No cracks or material separations after single 
lengthwise crease.
    7.2 Sampler. The air sampler shall provide means for drawing the air 
sample, via reduced pressure, through the filter at a uniform face 
velocity.
    7.2.1 The sampler shall have suitable means to:
    a. Hold and seal the filter to the sampler housing.
    b. Allow the filter to be changed conveniently.
    c. Preclude leaks that would cause error in the measurement of the 
air volume passing through the filter.
    d. ([dagger]) Manually adjust the flow rate to accommodate 
variations in filter pressure drop and site line voltage and altitude. 
The adjustment may be accomplished by an automatic flow controller or by 
a manual flow adjustment device. Any manual adjustment device must be 
designed with positive detents or other means to avoid unintentional 
changes in the setting.
---------------------------------------------------------------------------

    ([dagger]) See note at beginning of Section 7 of this appendix.
---------------------------------------------------------------------------

    7.2.2 Minimum sample flow rate, heavily loaded filter: 1.1 m\3\/min 
(39 ft\3\/min).[Dagger]
---------------------------------------------------------------------------

    [Dagger] These specifications are in actual air volume units; to 
convert to EPA standard air volume units, multiply the specifications by 
(Pb/Pstd)(298/T) where Pb and T are the 
barometric pressure in mm Hg (or kPa) and the temperature in K at the 
sampler, and Pstd is 760 mm Hg (or 101 kPa).
---------------------------------------------------------------------------

    7.2.3 Maximum sample flow rate, clean filter: 1.7 m\3\/min (60 
ft\3\/min).[Dagger]
    7.2.4 Blower Motor: The motor must be capable of continuous 
operation for 24-hr periods.
    7.3 Sampler shelter.
    7.3.1 The sampler shelter shall:
    a. Maintain the filter in a horizontal position at least 1 m above 
the sampler supporting surface so that sample air is drawn downward 
through the filter.
    b. Be rectangular in shape with a gabled roof, similar to the design 
shown in Figure 1.
    c. Cover and protect the filter and sampler from precipitation and 
other weather.
    d. Discharge exhaust air at least 40 cm from the sample air inlet.
    e. Be designed to minimize the collection of dust from the 
supporting surface by incorporating a baffle between the exhaust outlet 
and the supporting surface.
    7.3.2 The sampler cover or roof shall overhang the sampler housing 
somewhat, as shown in Figure 1, and shall be mounted so as to form an 
air inlet gap between the cover and the sampler housing walls. 
[dagger] This sample air inlet should be approximately 
uniform on all sides of the sampler. [dagger] The area of the 
sample air inlet must be sized to provide an effective particle capture 
air velocity of between 20 and 35 cm/sec at the recommended operational 
flow rate. The capture velocity is the sample air flow rate divided by 
the inlet area measured in a horizontal plane at the lower edge of the 
cover. [dagger] Ideally, the inlet area and operational flow 
rate should be selected to obtain a capture air velocity of 25 2 cm/sec.
    7.4 Flow rate measurement devices.
    7.4.1 The sampler shall incorporate a flow rate measurement device 
capable of indicating the total sampler flow rate. Two common types of 
flow indicators covered in the calibration procedure are (1) an 
electronic mass flowmeter and (2) an orifice or orifices

[[Page 42]]

located in the sample air stream together with a suitable pressure 
indicator such as a manometer, or aneroid pressure gauge. A pressure 
recorder may be used with an orifice to provide a continuous record of 
the flow. Other types of flow indicators (including rotameters) having 
comparable precision and accuracy are also acceptable.
    7.4.2 [dagger] The flow rate measurement device must be capable of 
being calibrated and read in units corresponding to a flow rate which is 
readable to the nearest 0.02 std m\3\/min over the range 1.0 to 1.8 std 
m\3\/min.
    7.5 Thermometer, to indicate the approximate air temperature at the 
flow rate measurement orifice, when temperature corrections are used.
    7.5.1 Range: -40[deg] to + 50 [deg]C (223-323 K).
    7.5.2 Resolution: 2 [deg]C (2 K).
    7.6 Barometer, to indicate barometric pressure at the flow rate 
measurement orifice, when pressure corrections are used.
    7.6.1 Range: 500 to 800 mm Hg (66-106 kPa).
    7.6.2 Resolution: 5 mm Hg (0.67 kPa).
    7.7 Timing/control device.
    7.7.1 The timing device must be capable of starting and stopping the 
sampler to obtain an elapsed run-time of 24 hr 1 
hr (1,440 60 min).
    7.7.2 Accuracy of time setting: 30 min, or 
better. (See Section 6.8).
    7.8 Flow rate transfer standard, traceable to a primary standard. 
(See Section 9.2.)
    7.8.1 Approximate range: 1.0 to 1.8 m\3\/min.
    7.8.2 Resolution: 0.02 m\3\/min.
    7.8.3 Reproducibility: 2 percent (2 times 
coefficient of variation) over normal ranges of ambient temperature and 
pressure for the stated flow rate range. (See Reference 2, Section 2.)
    7.8.4 Maximum pressure drop at 1.7 std m\3\/min; 50 cm H2 
O (5 kPa).
    7.8.5 The flow rate transfer standard must connect without leaks to 
the inlet of the sampler and measure the flow rate of the total air 
sample.
    7.8.6 The flow rate transfer standard must include a means to vary 
the sampler flow rate over the range of 1.0 to 1.8 m\3\/min (35-64 
ft\3\/min) by introducing various levels of flow resistance between the 
sampler and the transfer standard inlet.
    7.8.7 The conventional type of flow transfer standard consists of: 
An orifice unit with adapter that connects to the inlet of the sampler, 
a manometer or other device to measure orifice pressure drop, a means to 
vary the flow through the sampler unit, a thermometer to measure the 
ambient temperature, and a barometer to measure ambient pressure. Two 
such devices are shown in Figures 2a and 2b. Figure 2a shows multiple 
fixed resistance plates, which necessitate disassembly of the unit each 
time the flow resistance is changed. A preferable design, illustrated in 
Figure 2b, has a variable flow restriction that can be adjusted 
externally without disassembly of the unit. Use of a conventional, 
orifice-type transfer standard is assumed in the calibration procedure 
(Section 9). However, the use of other types of transfer standards 
meeting the above specifications, such as the one shown in Figure 2c, 
may be approved; see the note following Section 9.1.
    7.9 Filter conditioning environment
    7.9.1 Controlled temperature: between 15[deg] and 30 [deg]C with 
less than 3 [deg]C variation during equilibration 
period.
    7.9.2 Controlled humidity: Less than 50 percent relative humidity, 
constant within 5 percent.
    7.10 Analytical balance.
    7.10.1 Sensitivity: 0.1 mg.
    7.10.2 Weighing chamber designed to accept an unfolded 20.3 x 25.4 
cm (8 x 10 in) filter.
    7.11 Area light source, similar to X-ray film viewer, to backlight 
filters for visual inspection.
    7.12 Numbering device, capable of printing identification numbers on 
the filters before they are placed in the filter conditioning 
environment, if not numbered by the supplier.
    8.0 Procedure.
    (See References 1 and 2 for quality assurance information.)
    8.1 Number each filter, if not already numbered, near its edge with 
a unique identification number.
    8.2 Backlight each filter and inspect for pinholes, particles, and 
other imperfections; filters with visible imperfections must not be 
used.
    8.3 Equilibrate each filter in the conditioning environment for at 
least 24-hr.
    8.4 Following equilibration, weigh each filter to the nearest 
milligram and record this tare weight (Wi) with the filter 
identification number.
    8.5 Do not bend or fold the filter before collection of the sample.
    8.6 Open the shelter and install a numbered, preweighed filter in 
the sampler, following the sampler manufacturer's instructions. During 
inclement weather, precautions must be taken while changing filters to 
prevent damage to the clean filter and loss of sample from or damage to 
the exposed filter. Filter cassettes that can be loaded and unloaded in 
the laboratory may be used to minimize this problem (See Section 6.6).
    8.7 Close the shelter and run the sampler for at least 5 min to 
establish run-temperature conditions.
    8.8 Record the flow indicator reading and, if needed, the barometric 
pressure (P\3\3) and the ambient temperature 
(T\3\3) see NOTE following step 8.12). Stop the sampler. 
Determine the sampler flow rate (see Section 10.1); if it is outside the 
acceptable range (1.1 to 1.7 m\3\/min [39-60 ft\3\/min]), use a 
different filter, or adjust the sampler flow rate. Warning: Substantial 
flow adjustments may affect the

[[Page 43]]

calibration of the orifice-type flow indicators and may necessitate 
recalibration.
    8.9 Record the sampler identification information (filter number, 
site location or identification number, sample date, and starting time).
    8.10 Set the timer to start and stop the sampler such that the 
sampler runs 24-hrs, from midnight to midnight (local time).
    8.11 As soon as practical following the sampling period, run the 
sampler for at least 5 min to again establish run-temperature 
conditions.
    8.12 Record the flow indicator reading and, if needed, the 
barometric pressure (P\3\3) and the ambient temperature 
(T\3\3).

    Note: No onsite pressure or temperature measurements are necessary 
if the sampler flow indicator does not require pressure or temperature 
corrections (e.g., a mass flowmeter) or if average barometric pressure 
and seasonal average temperature for the site are incorporated into the 
sampler calibration (see step 9.3.9). For individual pressure and 
temperature corrections, the ambient pressure and temperature can be 
obtained by onsite measurements or from a nearby weather station. 
Barometric pressure readings obtained from airports must be station 
pressure, not corrected to sea level, and may need to be corrected for 
differences in elevation between the sampler site and the airport. For 
samplers having flow recorders but not constant flow controllers, the 
average temperature and pressure at the site during the sampling period 
should be estimated from weather bureau or other available data.

    8.13 Stop the sampler and carefully remove the filter, following the 
sampler manufacturer's instructions. Touch only the outer edges of the 
filter. See the precautions in step 8.6.
    8.14 Fold the filter in half lengthwise so that only surfaces with 
collected particulate matter are in contact and place it in the filter 
holder (glassine envelope or manila folder).
    8.15 Record the ending time or elapsed time on the filter 
information record, either from the stop set-point time, from an elapsed 
time indicator, or from a continuous flow record. The sample period must 
be 1,440 60 min. for a valid sample.
    8.16 Record on the filter information record any other factors, such 
as meteorological conditions, construction activity, fires or dust 
storms, etc., that might be pertinent to the measurement. If the sample 
is known to be defective, void it at this time.
    8.17 Equilibrate the exposed filter in the conditioning environment 
for at least 24-hrs.
    8.18 Immediately after equilibration, reweigh the filter to the 
nearest milligram and record the gross weight with the filter 
identification number. See Section 10 for TSP concentration 
calculations.
    9.0 Calibration.
    9.1 Calibration of the high volume sampler's flow indicating or 
control device is necessary to establish traceability of the field 
measurement to a primary standard via a flow rate transfer standard. 
Figure 3a illustrates the certification of the flow rate transfer 
standard and Figure 3b illustrates its use in calibrating a sampler flow 
indicator. Determination of the corrected flow rate from the sampler 
flow indicator, illustrated in Figure 3c, is addressed in Section 10.1

    Note: The following calibration procedure applies to a conventional 
orifice-type flow transfer standard and an orifice-type flow indicator 
in the sampler (the most common types). For samplers using a pressure 
recorder having a square-root scale, 3 other acceptable calibration 
procedures are provided in Reference 12. Other types of transfer 
standards may be used if the manufacturer or user provides an 
appropriately modified calibration procedure that has been approved by 
EPA under Section 2.8 of appendix C to part 58 of this chapter.

    9.2 Certification of the flow rate transfer standard.
    9.2.1 Equipment required: Positive displacement standard volume 
meter traceable to the National Bureau of Standards (such as a Roots 
meter or equivalent), stop-watch, manometer, thermometer, and barometer.
    9.2.2 Connect the flow rate transfer standard to the inlet of the 
standard volume meter. Connect the manometer to measure the pressure at 
the inlet of the standard volume meter. Connect the orifice manometer to 
the pressure tap on the transfer standard. Connect a high-volume air 
pump (such as a high-volume sampler blower) to the outlet side of the 
standard volume meter. See Figure 3a.
    9.2.3 Check for leaks by temporarily clamping both manometer lines 
(to avoid fluid loss) and blocking the orifice with a large-diameter 
rubber stopper, wide cellophane tape, or other suitable means. Start the 
high-volume air pump and note any change in the standard volume meter 
reading. The reading should remain constant. If the reading changes, 
locate any leaks by listening for a whistling sound and/or retightening 
all connections, making sure that all gaskets are properly installed.
    9.2.4 After satisfactorily completing the leak check as described 
above, unclamp both manometer lines and zero both manometers.
    9.2.5 Achieve the appropriate flow rate through the system, either 
by means of the variable flow resistance in the transfer standard or by 
varying the voltage to the air pump. (Use of resistance plates as shown 
in Figure 1a is discouraged because the above leak check must be 
repeated each time a new resistance plate is installed.) At least five

[[Page 44]]

different but constant flow rates, evenly distributed, with at least 
three in the specified flow rate interval (1.1 to 1.7 m\3\/min [39-60 
ft\3\/min]), are required.
    9.2.6 Measure and record the certification data on a form similar to 
the one illustrated in Figure 4 according to the following steps.
    9.2.7 Observe the barometric pressure and record as P1 
(item 8 in Figure 4).
    9.2.8 Read the ambient temperature in the vicinity of the standard 
volume meter and record it as T1 (item 9 in Figure 4).
    9.2.9 Start the blower motor, adjust the flow, and allow the system 
to run for at least 1 min for a constant motor speed to be attained.
    9.2.10 Observe the standard volume meter reading and simultaneously 
start a stopwatch. Record the initial meter reading (Vi) in 
column 1 of Figure 4.
    9.2.11 Maintain this constant flow rate until at least 3 m\3\ of air 
have passed through the standard volume meter. Record the standard 
volume meter inlet pressure manometer reading as [Delta]P (column 5 in 
Figure 4), and the orifice manometer reading as [Delta]H (column 7 in 
Figure 4). Be sure to indicate the correct units of measurement.
    9.2.12 After at least 3 m\3\ of air have passed through the system, 
observe the standard volume meter reading while simultaneously stopping 
the stopwatch. Record the final meter reading (Vf) in column 
2 and the elapsed time (t) in column 3 of Figure 4.
    9.2.13 Calculate the volume measured by the standard volume meter at 
meter conditions of temperature and pressures as Vm = 
Vf-Vi. Record in column 4 of Figure 4.
    9.2.14 Correct this volume to standard volume (std m\3\) as follows:
    [GRAPHIC] [TIFF OMITTED] TR31AU93.024
    
where:

Vstd = standard volume, std m\3\;
Vm = actual volume measured by the standard volume meter;
P1 = barometric pressure during calibration, mm Hg or kPa;
[Delta]P = differential pressure at inlet to volume meter, mm Hg or kPa;
Pstd = 760 mm Hg or 101 kPa;
Tstd = 298 K;
T1 = ambient temperature during calibration, K.
Calculate the standard flow rate (std m\3\/min) as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.013

where:

Qstd = standard volumetric flow rate, std m\3\/min
t = elapsed time, minutes.

    Record Qstd to the nearest 0.01 std m\3\/min in column 6 
of Figure 4.
    9.2.15 Repeat steps 9.2.9 through 9.2.14 for at least four 
additional constant flow rates, evenly spaced over the approximate range 
of 1.0 to 1.8 std m\3\/min (35-64 ft\3\/min).
    9.2.16 For each flow, compute

[radic][Delta][Delta]H (P1/Pstd)(298/
          T1)

(column 7a of Figure 4) and plot these value against Qstd as 
shown in Figure 3a. Be sure to use consistent units (mm Hg or kPa) for 
barometric pressure. Draw the orifice transfer standard certification 
curve or calculate the linear least squares slope (m) and intercept (b) 
of the certification curve:

[radic][Delta][Delta]H (P1/Pstd)(298/
          T1)

 = mQstd + b. See Figures 3 and 4. A certification graph 
should be readable to 0.02 std m\3\/min.
    9.2.17 Recalibrate the transfer standard annually or as required by 
applicable quality control procedures. (See Reference 2.)
    9.3 Calibration of sampler flow indicator.

    Note: For samplers equipped with a flow controlling device, the flow 
controller must be disabled to allow flow changes during calibration of 
the sampler's flow indicator, or the alternate calibration of the flow 
controller given in 9.4 may be used. For samplers using an orifice-type 
flow indicator downstream of the motor, do not vary the flow rate by 
adjusting the voltage or power supplied to the sampler.

    9.3.1 A form similar to the one illustrated in Figure 5 should be 
used to record the calibration data.
    9.3.2 Connect the transfer standard to the inlet of the sampler. 
Connect the orifice manometer to the orifice pressure tap, as 
illustrated in Figure 3b. Make sure there are no leaks between the 
orifice unit and the sampler.
    9.3.3 Operate the sampler for at least 5 minutes to establish 
thermal equilibrium prior to the calibration.
    9.3.4 Measure and record the ambient temperature, T2, and 
the barometric pressure, P2, during calibration.
    9.3.5 Adjust the variable resistance or, if applicable, insert the 
appropriate resistance plate (or no plate) to achieve the desired flow 
rate.
    9.3.6 Let the sampler run for at least 2 min to re-establish the 
run-temperature conditions. Read and record the pressure drop across the 
orifice ([Delta]H) and the sampler flow rate indication (I) in the 
appropriate columns of Figure 5.
    9.3.7 Calculate [radic][Delta][Delta]H(P2/
Pstd)(298/T2) and determine the flow rate at 
standard conditions (Qstd) either graphically from the 
certification curve or by calculating Qstd from the least 
square slope and intercept of the transfer standard's transposed 
certification curve:

[[Page 45]]

Qstd = 1/m [radic][Delta]H(P2/
Pstd)(298/T2)-b. Record the value of 
Qstd on Figure 5.
    9.3.8 Repeat steps 9.3.5, 9.3.6, and 9.3.7 for several additional 
flow rates distributed over a range that includes 1.1 to 1.7 std m\3\/
min.
    9.3.9 Determine the calibration curve by plotting values of the 
appropriate expression involving I, selected from table 1, against 
Qstd. The choice of expression from table 1 depends on the 
flow rate measurement device used (see Section 7.4.1) and also on 
whether the calibration curve is to incorporate geographic average 
barometric pressure (Pa) and seasonal average temperature 
(Ta) for the site to approximate actual pressure and 
temperature. Where Pa and Ta can be determined for 
a site for a seasonal period such that the actual barometric pressure 
and temperature at the site do not vary by more than 60 mm Hg (8 kPa) from Pa or 15 [deg]C from Ta, respectively, then using 
Pa and Ta avoids the need for subsequent pressure 
and temperature calculation when the sampler is used. The geographic 
average barometric pressure (Pa) may be estimated from an 
altitude-pressure table or by making an (approximate) elevation 
correction of -26 mm Hg (-3.46 kPa) for each 305 m (1,000 ft) above sea 
level (760 mm Hg or 101 kPa). The seasonal average temperature 
(Ta) may be estimated from weather station or other records. 
Be sure to use consistent units (mm Hg or kPa) for barometric pressure.
    9.3.10 Draw the sampler calibration curve or calculate the linear 
least squares slope (m), intercept (b), and correlation coefficient of 
the calibration curve: [Expression from table 1]= mQstd + b. 
See Figures 3 and 5. Calibration curves should be readable to 0.02 std 
m\3\/min.
    9.3.11 For a sampler equipped with a flow controller, the flow 
controlling mechanism should be re-enabled and set to a flow near the 
lower flow limit to allow maximum control range. The sample flow rate 
should be verified at this time with a clean filter installed. Then add 
two or more filters to the sampler to see if the flow controller 
maintains a constant flow; this is particularly important at high 
altitudes where the range of the flow controller may be reduced.
    9.4 Alternate calibration of flow-controlled samplers. A flow-
controlled sampler may be calibrated solely at its controlled flow rate, 
provided that previous operating history of the sampler demonstrates 
that the flow rate is stable and reliable. In this case, the flow 
indicator may remain uncalibrated but should be used to indicate any 
relative change between initial and final flows, and the sampler should 
be recalibrated more often to minimize potential loss of samples because 
of controller malfunction.
    9.4.1 Set the flow controller for a flow near the lower limit of the 
flow range to allow maximum control range.
    9.4.2 Install a clean filter in the sampler and carry out steps 
9.3.2, 9.3.3, 9.3.4, 9.3.6, and 9.3.7.
    9.4.3 Following calibration, add one or two additional clean filters 
to the sampler, reconnect the transfer standard, and operate the sampler 
to verify that the controller maintains the same calibrated flow rate; 
this is particularly important at high altitudes where the flow control 
range may be reduced.

[[Page 46]]





    10.0 Calculations of TSP Concentration.
    10.1 Determine the average sampler flow rate during the sampling 
period according to either 10.1.1 or 10.1.2 below.
    10.1.1 For a sampler without a continuous flow recorder, determine 
the appropriate expression to be used from table 2 corresponding to the 
one from table 1 used in step 9.3.9. Using this appropriate expression, 
determine Qstd for the initial flow rate from the sampler 
calibration curve, either graphically or from the transposed regression 
equation:

Qstd =
1/m ([Appropriate expression from table 2]-b)

Similarly, determine Qstd from the final flow reading, and 
calculate the average flow Qstd as one-half the sum of the 
initial and final flow rates.

[[Page 47]]

    10.1.2 For a sampler with a continuous flow recorder, determine the 
average flow rate device reading, I, for the period. Determine the 
appropriate expression from table 2 corresponding to the one from table 
1 used in step 9.3.9. Then using this expression and the average flow 
rate reading, determine Qstd from the sampler calibration 
curve, either graphically or from the transposed regression equation:

Qstd =

1/m ([Appropriate expression from table 2]-b)
    If the trace shows substantial flow change during the sampling 
period, greater accuracy may be achieved by dividing the sampling period 
into intervals and calculating an average reading before determining 
Qstd.
    10.2 Calculate the total air volume sampled as:

V - Qstd x t

where:

V = total air volume sampled, in standard volume units, std m\3\/;
Qstd = average standard flow rate, std m\3\/min;
t = sampling time, min.

    10.3 Calculate and report the particulate matter concentration as:
    [GRAPHIC] [TIFF OMITTED] TR31AU93.025
    
where:

TSP = mass concentration of total suspended particulate matter, 
          [micro]g/std m\3\;
Wi = initial weight of clean filter, g;
Wf = final weight of exposed filter, g;
V = air volume sampled, converted to standard conditions, std m\3\,
10\6\ = conversion of g to [micro]g.

    10.4 If desired, the actual particulate matter concentration (see 
Section 2.2) can be calculated as follows:

(TSP)a = TSP (P3/Pstd)(298/
          T3)

where:

(TSP)a = actual concentration at field conditions, [micro]g/
          m\3\;
TSP = concentration at standard conditions, [micro]g/std m\3\;
P3 = average barometric pressure during sampling period, mm 
          Hg;
Pstd = 760 mn Hg (or 101 kPa);
T3 = average ambient temperature during sampling period, K.

    11.0 References.
    1. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume I, Principles. EPA-600/9-76-005, U.S. Environmental Protection 
Agency, Research Triangle Park, NC 27711, 1976.
    2. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume II, Ambient Air Specific Methods. EPA-600/4-77-027a, U.S. 
Environmental Protection Agency, Research Triangle Park, NC 27711, 1977.
    3. Wedding, J. B., A. R. McFarland, and J. E. Cernak. Large Particle 
Collection Characteristics of Ambient Aerosol Samplers. Environ. Sci. 
Technol. 11:387-390, 1977.
    4. McKee, H. C., et al. Collaborative Testing of Methods to Measure 
Air Pollutants, I. The High-Volume Method for Suspended Particulate 
Matter. J. Air Poll. Cont. Assoc., 22 (342), 1972.
    5. Clement, R. E., and F. W. Karasek. Sample Composition Changes in 
Sampling and Analysis of Organic Compounds in Aerosols. The Intern. J. 
Environ. Anal. Chem., 7:109, 1979.
    6. Lee, R. E., Jr., and J. Wagman. A Sampling Anomaly in the 
Determination of Atmospheric Sulfuric Concentration. Am. Ind. Hygiene 
Assoc. J., 27:266, 1966.
    7. Appel, B. R., et al. Interference Effects in Sampling Particulate 
Nitrate in Ambient Air. Atmospheric Environment, 13:319, 1979.
    8. Tierney, G. P., and W. D. Conner. Hygroscopic Effects on Weight 
Determinations of Particulates Collected on Glass-Fiber Filters. Am. 
Ind. Hygiene Assoc. J., 28:363, 1967.
    9. Chahal, H. S., and D. J. Romano. High-Volume Sampling Effect of 
Windborne Particulate Matter Deposited During Idle Periods. J. Air Poll. 
Cont. Assoc., Vol. 26 (885), 1976.
    10. Patterson, R. K. Aerosol Contamination from High-Volume Sampler 
Exhaust. J. Air Poll. Cont. Assoc., Vol. 30 (169), 1980.
    11. EPA Test Procedures for Determining pH and Integrity of High-
Volume Air Filters. QAD/M-80.01. Available from the Methods 
Standardization Branch, Quality Assurance Division, Environmental 
Monitoring Systems Laboratory (MD-77), U.S. Environmental Protection 
Agency, Research Triangle Park, NC 27711, 1980.
    12. Smith, F., P. S. Wohlschlegel, R. S. C. Rogers, and D. J. 
Mulligan. Investigation of Flow Rate Calibration Procedures Associated 
with the High-Volume Method for Determination of Suspended Particulates. 
EPA-600/4-78-047, U.S. Environmental Protection Agency, Research 
Triangle Park, NC, June 1978.

[[Page 48]]




[[Page 49]]





[[Page 50]]





[[Page 51]]





[[Page 52]]





[47 FR 54912, Dec. 6, 1982; 48 FR 17355, Apr. 22, 1983]



   Sec. Appendix C to Part 50--Measurement Principle and Calibration 
Procedure for the Measurement of Carbon Monoxide in the Atmosphere (Non-
                     Dispersive Infrared Photometry)

                            1.0 Applicability

    1.1 This non-dispersive infrared photometry (NDIR) Federal Reference 
Method (FRM) provides measurements of the concentration of carbon 
monoxide (CO) in ambient air for determining compliance with the primary 
and secondary National Ambient Air Quality Standards (NAAQS) for CO as 
specified in Sec. 50.8 of this chapter. The method is applicable to 
continuous sampling and measurement of ambient CO concentrations 
suitable for determining 1-hour or longer average measurements. The 
method may also provide measurements of shorter averaging times, subject 
to specific analyzer performance limitations. Additional CO monitoring 
quality assurance procedures and guidance

[[Page 53]]

are provided in part 58, appendix A, of this chapter and in reference 1 
of this appendix C.

                        2.0 Measurement Principle

    2.1 Measurements of CO in ambient air are based on automated 
measurement of the absorption of infrared radiation by CO in an ambient 
air sample drawn into an analyzer employing non-wavelength-dispersive, 
infrared photometry (NDIR method). Infrared energy from a source in the 
photometer is passed through a cell containing the air sample to be 
analyzed, and the quantitative absorption of energy by CO in the sample 
cell is measured by a suitable detector. The photometer is sensitized 
specifically to CO by employing CO gas in a filter cell in the optical 
path, which, when compared to a differential optical path without a CO 
filter cell, limits the measured absorption to one or more of the 
characteristic wavelengths at which CO strongly absorbs. However, to 
meet measurement performance requirements, various optical filters, 
reference cells, rotating gas filter cells, dual-beam configurations, 
moisture traps, or other means may also be used to further enhance 
sensitivity and stability of the photometer and to minimize potential 
measurement interference from water vapor, carbon dioxide 
(CO2), or other species. Also, various schemes may be used to 
provide a suitable zero reference for the photometer, and optional 
automatic compensation may be provided for the actual pressure and 
temperature of the air sample in the measurement cell. The measured 
infrared absorption, converted to a digital reading or an electrical 
output signal, indicates the measured CO concentration.
    2.2 The measurement system is calibrated by referencing the 
analyzer's CO measurements to CO concentration standards traceable to a 
National Institute of Standards and Technology (NIST) primary standard 
for CO, as described in the associated calibration procedure specified 
in section 4 of this reference method.
    2.3 An analyzer implementing this measurement principle will be 
considered a reference method only if it has been designated as a 
reference method in accordance with part 53 of this chapter.
    2.4 Sampling considerations. The use of a particle filter in the 
sample inlet line of a CO FRM analyzer is optional and left to the 
discretion of the user unless such a filter is specified or recommended 
by the analyzer manufacturer in the analyzer's associated operation or 
instruction manual.

                            3.0 Interferences

    3.1 The NDIR measurement principle is potentially susceptible to 
interference from water vapor and CO2, which have some 
infrared absorption at wavelengths in common with CO and normally exist 
in the atmosphere. Various instrumental techniques can be used to 
effectively minimize these interferences.

                       4.0 Calibration Procedures

    4.1 Principle. Either of two methods may be selected for dynamic 
multipoint calibration of FRM CO analyzers, using test gases of 
accurately known CO concentrations obtained from one or more compressed 
gas cylinders certified as CO transfer standards:
    4.1.1 Dilution method: A single certified standard cylinder of CO is 
quantitatively diluted as necessary with zero air to obtain the various 
calibration concentration standards needed.
    4.1.2 Multiple-cylinder method: Multiple, individually certified 
standard cylinders of CO are used for each of the various calibration 
concentration standards needed.
    4.1.3 Additional information on calibration may be found in Section 
12 of reference 1.
    4.2 Apparatus. The major components and typical configurations of 
the calibration systems for the two calibration methods are shown in 
Figures 1 and 2. Either system may be made up using common laboratory 
components, or it may be a commercially manufactured system. In either 
case, the principal components are as follows:
    4.2.1 CO standard gas flow control and measurement devices (or a 
combined device) capable of regulating and maintaining the standard gas 
flow rate constant to within 2 percent and 
measuring the gas flow rate accurate to within 2 
percent, properly calibrated to a NIST-traceable standard.
    4.2.2 For the dilution method (Figure 1), dilution air flow control 
and measurement devices (or a combined device) capable of regulating and 
maintaining the air flow rate constant to within 2 
percent and measuring the air flow rate accurate to within 2 percent, properly calibrated to a NIST-traceable 
standard.
    4.2.3 Standard gas pressure regulator(s) for the standard CO 
cylinder(s), suitable for use with a high-pressure CO gas cylinder and 
having a non-reactive diaphragm and internal parts and a suitable 
delivery pressure.
    4.2.4 Mixing chamber for the dilution method of an inert material 
and of proper design to provide thorough mixing of CO standard gas and 
diluent air streams.
    4.2.5 Output sampling manifold, constructed of an inert material and 
of sufficient diameter to ensure an insignificant pressure drop at the 
analyzer connection. The system must have a vent designed to ensure 
nearly atmospheric pressure at the analyzer connection port and to 
prevent ambient air from entering the manifold.

                              4.3 Reagents

    4.3.1 CO gas concentration transfer standard(s) of CO in air, 
containing an appropriate

[[Page 54]]

concentration of CO suitable for the selected operating range of the 
analyzer under calibration and traceable to a NIST standard reference 
material (SRM). If the CO analyzer has significant sensitivity to 
CO2, the CO standard(s) should also contain 350 to 400 ppm 
CO2 to replicate the typical CO2 concentration in 
ambient air. However, if the zero air dilution ratio used for the 
dilution method is not less than 100:1 and the zero air contains ambient 
levels of CO2, then the CO standard may be contained in 
nitrogen and need not contain CO2.
    4.3.2 For the dilution method, clean zero air, free of contaminants 
that could cause a detectable response on or a change in sensitivity of 
the CO analyzer. The zero air should contain <0.1 ppm CO.

                 4.4 Procedure Using the Dilution Method

    4.4.1 Assemble or obtain a suitable dynamic dilution calibration 
system such as the one shown schematically in Figure 1. Generally, all 
calibration gases including zero air must be introduced into the sample 
inlet of the analyzer. However, if the analyzer has special, approved 
zero and span inlets and automatic valves to specifically allow 
introduction of calibration standards at near atmospheric pressure, such 
inlets may be used for calibration in lieu of the sample inlet. For 
specific operating instructions, refer to the manufacturer's manual.
    4.4.2 Ensure that there are no leaks in the calibration system and 
that all flowmeters are properly and accurately calibrated, under the 
conditions of use, if appropriate, against a reliable volume or flow 
rate standard such as a soap-bubble meter or wet-test meter traceable to 
a NIST standard. All volumetric flow rates should be corrected to the 
same temperature and pressure such as 298.15 K (25 [deg]C) and 760 mm Hg 
(101 kPa), using a correction formula such as the following:
[GRAPHIC] [TIFF OMITTED] TR31AU11.001

Where:

Fc = corrected flow rate (L/min at 25 [deg]C and 760 mm Hg),
Fm = measured flow rate (at temperature Tm and pressure Pm),
Pm = measured pressure in mm Hg (absolute), and
Tm = measured temperature in degrees Celsius.

    4.4.3 Select the operating range of the CO analyzer to be 
calibrated. Connect the measurement signal output of the analyzer to an 
appropriate readout instrument to allow the analyzer's measurement 
output to be continuously monitored during the calibration. Where 
possible, this readout instrument should be the same one used to record 
routine monitoring data, or, at least, an instrument that is as closely 
representative of that system as feasible.
    4.4.4 Connect the inlet of the CO analyzer to the output-sampling 
manifold of the calibration system.
    4.4.5 Adjust the calibration system to deliver zero air to the 
output manifold. The total air flow must exceed the total demand of the 
analyzer(s) connected to the output manifold to ensure that no ambient 
air is pulled into the manifold vent. Allow the analyzer to sample zero 
air until a stable response is obtained. After the response has 
stabilized, adjust the analyzer zero reading.
    4.4.6 Adjust the zero air flow rate and the CO gas flow rate from 
the standard CO cylinder to provide a diluted CO concentration of 
approximately 80 percent of the measurement upper range limit (URL) of 
the operating range of the analyzer. The total air flow rate must exceed 
the total demand of the analyzer(s) connected to the output manifold to 
ensure that no ambient air is pulled into the manifold vent. The exact 
CO concentration is calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU11.002

Where:

[CO]OUT = diluted CO concentration at the output manifold (ppm),
[CO]STD = concentration of the undiluted CO standard (ppm),

[[Page 55]]

FCO = flow rate of the CO standard (L/min), and
FD = flow rate of the dilution air (L/min).

Sample this CO concentration until a stable response is obtained. Adjust 
the analyzer span control to obtain the desired analyzer response 
reading equivalent to the calculated standard concentration. If 
substantial adjustment of the analyzer span control is required, it may 
be necessary to recheck the zero and span adjustments by repeating steps 
4.4.5 and 4.4.6. Record the CO concentration and the analyzer's final 
response.
    4.4.7 Generate several additional concentrations (at least three 
evenly spaced points across the remaining scale are suggested to verify 
linearity) by decreasing FCO or increasing FD. Be sure the total flow 
exceeds the analyzer's total flow demand. For each concentration 
generated, calculate the exact CO concentration using equation (2). 
Record the concentration and the analyzer's stable response for each 
concentration. Plot the analyzer responses (vertical or y-axis) versus 
the corresponding CO concentrations (horizontal or x-axis). Calculate 
the linear regression slope and intercept of the calibration curve and 
verify that no point deviates from this line by more than 2 percent of 
the highest concentration tested.
    4.5 Procedure Using the Multiple-Cylinder Method. Use the procedure 
for the dilution method with the following changes:
    4.5.1 Use a multi-cylinder, dynamic calibration system such as the 
typical one shown in Figure 2.
    4.5.2 The flowmeter need not be accurately calibrated, provided the 
flow in the output manifold can be verified to exceed the analyzer's 
flow demand.
    4.5.3 The various CO calibration concentrations required in Steps 
4.4.5, 4.4.6, and 4.4.7 are obtained without dilution by selecting zero 
air or the appropriate certified standard cylinder.
    4.6 Frequency of Calibration. The frequency of calibration, as well 
as the number of points necessary to establish the calibration curve and 
the frequency of other performance checking, will vary by analyzer. 
However, the minimum frequency, acceptance criteria, and subsequent 
actions are specified in reference 1, appendix D, ``Measurement Quality 
Objectives and Validation Template for CO'' (page 5 of 30). The user's 
quality control program should provide guidelines for initial 
establishment of these variables and for subsequent alteration as 
operational experience is accumulated. Manufacturers of CO analyzers 
should include in their instruction/operation manuals information and 
guidance as to these variables and on other matters of operation, 
calibration, routine maintenance, and quality control.

                              5.0 Reference

    1. QA Handbook for Air Pollution Measurement Systems--Volume II. 
Ambient Air Quality Monitoring Program. U.S. EPA. EPA-454/B-08-003 
(2008).
[GRAPHIC] [TIFF OMITTED] TR31AU11.003


[[Page 56]]


[GRAPHIC] [TIFF OMITTED] TR31AU11.004


[76 FR 54323, Aug. 31, 2011]



    Sec. Appendix D to Part 50--Reference Measurement Principle and 
  Calibration Procedure for the Measurement of Ozone in the Atmosphere 
                       (Chemiluminescence Method)

    1.0 Applicability.
    1.1 This chemiluminescence method provides reference measurements of 
the concentration of ozone (O3) in ambient air for 
determining compliance with the national primary and secondary ambient 
air quality standards for O3 as specified in 40 CFR part 50. 
This automated method is applicable to the measurement of ambient 
O3 concentrations using continuous (real-time) sampling and 
analysis. Additional quality assurance procedures and guidance are 
provided in 40 CFR part 58, appendix A, and in Reference 14.
    2.0 Measurement Principle.
    2.1 This reference method is based on continuous automated 
measurement of the intensity of the characteristic chemiluminescence 
released by the gas phase reaction of O3 in sampled air with 
either ethylene (C2H4) or nitric oxide (NO) gas. 
An ambient air sample stream and a specific flowing concentration of 
either C2H4 (ET-CL method) or NO (NO-CL method) 
are mixed in a measurement cell, where the resulting chemiluminescence 
is quantitatively measured by a sensitive photo-detector. References 8-
11 describe the chemiluminescence measurement principle.
    2.2 The measurement system is calibrated by referencing the 
instrumental chemiluminescence measurements to certified O3 
standard concentrations generated in a dynamic flow system and assayed 
by photometry to be traceable to a National Institute of Standards and 
Technology (NIST) standard reference photometer for O3 (see 
Section 4, Calibration Procedure, below).
    2.3 An analyzer implementing this measurement principle is shown 
schematically in Figure 1. Designs implementing this measurement 
principle must include: an appropriately designed mixing and measurement 
cell; a suitable quantitative photometric measurement system with 
adequate sensitivity and wavelength specificity for O3; a 
pump, flow control, and sample conditioning system for sampling the 
ambient air and moving it into and through the measurement cell; a 
sample air dryer as necessary to meet the water vapor interference limit 
requirement specified in subpart B of part 53 of this chapter; a means 
to supply, meter, and mix a constant, flowing stream of either 
C2H4 or NO gas of fixed concentration with the 
sample air flow in the measurement cell; suitable electronic control and 
measurement processing capability; and other associated apparatus as may 
be necessary. The analyzer must be designed and constructed to provide 
accurate, repeatable, and continuous measurements of O3 
concentrations in ambient air, with measurement performance that meets 
the requirements specified in subpart B of part 53 of this chapter.

[[Page 57]]

    2.4 An analyzer implementing this measurement principle and 
calibration procedure will be considered a federal reference method 
(FRM) only if it has been designated as a reference method in accordance 
with part 53 of this chapter.
    2.5 Sampling considerations. The use of a particle filter on the 
sample inlet line of a chemiluminescence O3 FRM analyzer is 
required to prevent buildup of particulate matter in the measurement 
cell and inlet components. This filter must be changed weekly (or at 
least often as specified in the manufacturer's operation/instruction 
manual), and the sample inlet system used with the analyzer must be kept 
clean, to avoid loss of O3 in the O3 sample air 
prior to the concentration measurement.
    3.0 Interferences.
    3.1 Except as described in 3.2 below, the chemiluminescence 
measurement system is inherently free of significant interferences from 
other pollutant substances that may be present in ambient air.
    3.2 A small sensitivity to variations in the humidity of the sample 
air is minimized by a sample air dryer. Potential loss of O3 
in the inlet air filter and in the air sample handling components of the 
analyzer and associated exterior air sampling components due to buildup 
of airborne particulate matter is minimized by filter replacement and 
cleaning of the other inlet components.
    4.0 Calibration Procedure.
    4.1 Principle. The calibration procedure is based on the photometric 
assay of O3 concentrations in a dynamic flow system. The 
concentration of O3 in an absorption cell is determined from 
a measurement of the amount of 254 nm light absorbed by the sample. This 
determination requires knowledge of (1) the absorption coefficient 
([alpha]) of O3 at 254 nm, (2) the optical path length (l) 
through the sample, (3) the transmittance of the sample at a nominal 
wavelength of 254 nm, and (4) the temperature (T) and pressure (P) of 
the sample. The transmittance is defined as the ratio I/I0, 
where I is the intensity of light which passes through the cell and is 
sensed by the detector when the cell contains an O3 sample, 
and I0 is the intensity of light which passes through the 
cell and is sensed by the detector when the cell contains zero air. It 
is assumed that all conditions of the system, except for the contents of 
the absorption cell, are identical during measurement of I and 
I0. The quantities defined above are related by the Beer-
Lambert absorption law,
[GRAPHIC] [TIFF OMITTED] TR26OC15.002

Where:

[alpha] = absorption coefficient of O3 at 254 nm = 308 4 atm-1 cm-1 at 0 [deg]C and 760 torr, \1 2 3 
          4 5 6 7\
c = O3 concentration in atmospheres, and
l = optical path length in cm.

    A stable O3 generator is used to produce O3 
concentrations over the required calibration concentration range. Each 
O3 concentration is determined from the measurement of the 
transmittance (I/I0) of the sample at 254 nm with a 
photometer of path length l and calculated from the equation,
[GRAPHIC] [TIFF OMITTED] TR26OC15.003

    The calculated O3 concentrations must be corrected for 
O3 losses, which may occur in the photometer, and for the 
temperature and pressure of the sample.
    4.2 Applicability. This procedure is applicable to the calibration 
of ambient air O3 analyzers, either directly or by means of a 
transfer standard certified by this procedure. Transfer standards must 
meet the requirements and specifications set forth in Reference 12.

[[Page 58]]

    4.3 Apparatus. A complete UV calibration system consists of an 
O3 generator, an output port or manifold, a photometer, an 
appropriate source of zero air, and other components as necessary. The 
configuration must provide a stable O3 concentration at the 
system output and allow the photometer to accurately assay the output 
concentration to the precision specified for the photometer (4.3.1). 
Figure 2 shows a commonly used configuration and serves to illustrate 
the calibration procedure, which follows. Other configurations may 
require appropriate variations in the procedural steps. All connections 
between components in the calibration system downstream of the 
O3 generator must be of glass, Teflon, or other relatively 
inert materials. Additional information regarding the assembly of a UV 
photometric calibration apparatus is given in Reference 13. For 
certification of transfer standards which provide their own source of 
O3, the transfer standard may replace the O3 
generator and possibly other components shown in Figure 2; see Reference 
12 for guidance.
    4.3.1 UV photometer. The photometer consists of a low-pressure 
mercury discharge lamp, (optional) collimation optics, an absorption 
cell, a detector, and signal-processing electronics, as illustrated in 
Figure 2. It must be capable of measuring the transmittance, I/
I0, at a wavelength of 254 nm with sufficient precision such 
that the standard deviation of the concentration measurements does not 
exceed the greater of 0.005 ppm or 3% of the concentration. Because the 
low-pressure mercury lamp radiates at several wavelengths, the 
photometer must incorporate suitable means to assure that no 
O3 is generated in the cell by the lamp, and that at least 
99.5% of the radiation sensed by the detector is 254 nm radiation. (This 
can be readily achieved by prudent selection of optical filter and 
detector response characteristics.) The length of the light path through 
the absorption cell must be known with an accuracy of at least 99.5%. In 
addition, the cell and associated plumbing must be designed to minimize 
loss of O3 from contact with cell walls and gas handling 
components. See Reference 13 for additional information.
    4.3.2 Air flow controllers. Air flow controllers are devices capable 
of regulating air flows as necessary to meet the output stability and 
photometer precision requirements.
    4.3.3 Ozone generator. The ozone generator used must be capable of 
generating stable levels of O3 over the required 
concentration range.
    4.3.4 Output manifold. The output manifold must be constructed of 
glass, Teflon, or other relatively inert material, and should be of 
sufficient diameter to insure a negligible pressure drop at the 
photometer connection and other output ports. The system must have a 
vent designed to insure atmospheric pressure in the manifold and to 
prevent ambient air from entering the manifold.
    4.3.5 Two-way valve. A manual or automatic two-way valve, or other 
means is used to switch the photometer flow between zero air and the 
O3 concentration.
    4.3.6 Temperature indicator. A device to indicate temperature must 
be used that is accurate to 1 [deg]C.
    4.3.7 Barometer or pressure indicator. A device to indicate 
barometric pressure must be used that is accurate to 2 torr.
    4.4 Reagents.
    4.4.1 Zero air. The zero air must be free of contaminants which 
would cause a detectable response from the O3 analyzer, and 
it must be free of NO, C2H4, and other species 
which react with O3. A procedure for generating suitable zero 
air is given in Reference 13. As shown in Figure 2, the zero air 
supplied to the photometer cell for the I0 reference 
measurement must be derived from the same source as the zero air used 
for generation of the O3 concentration to be assayed (I 
measurement). When using the photometer to certify a transfer standard 
having its own source of O3, see Reference 12 for guidance on 
meeting this requirement.
    4.5 Procedure.
    4.5.1 General operation. The calibration photometer must be 
dedicated exclusively to use as a calibration standard. It must always 
be used with clean, filtered calibration gases, and never used for 
ambient air sampling. A number of advantages are realized by locating 
the calibration photometer in a clean laboratory where it can be 
stationary, protected from the physical shock of transportation, 
operated by a responsible analyst, and used as a common standard for all 
field calibrations via transfer standards.
    4.5.2 Preparation. Proper operation of the photometer is of critical 
importance to the accuracy of this procedure. Upon initial operation of 
the photometer, the following steps must be carried out with all 
quantitative results or indications recorded in a chronological record, 
either in tabular form or plotted on a graphical chart. As the 
performance and stability record of the photometer is established, the 
frequency of these steps may be reduced to be consistent with the 
documented stability of the photometer and the guidance provided in 
Reference 12.
    4.5.2.1 Instruction manual. Carry out all set up and adjustment 
procedures or checks as described in the operation or instruction manual 
associated with the photometer.
    4.5.2.2 System check. Check the photometer system for integrity, 
leaks, cleanliness, proper flow rates, etc. Service or replace filters 
and zero air scrubbers or other consumable materials, as necessary.

[[Page 59]]

    4.5.2.3 Linearity. Verify that the photometer manufacturer has 
adequately established that the linearity error of the photometer is 
less than 3%, or test the linearity by dilution as follows: Generate and 
assay an O3 concentration near the upper range limit of the 
system or appropriate calibration scale for the instrument, then 
accurately dilute that concentration with zero air and re-assay it. 
Repeat at several different dilution ratios. Compare the assay of the 
original concentration with the assay of the diluted concentration 
divided by the dilution ratio, as follows
[GRAPHIC] [TIFF OMITTED] TR26OC15.004

Where:

E = linearity error, percent
A1 = assay of the original concentration
A2 = assay of the diluted concentration
R = dilution ratio = flow of original concentration divided by the total 
          flow

    The linearity error must be less than 5%. Since the accuracy of the 
measured flow-rates will affect the linearity error as measured this 
way, the test is not necessarily conclusive. Additional information on 
verifying linearity is contained in Reference 13.
    4.5.2.4 Inter-comparison. The photometer must be inter-compared 
annually, either directly or via transfer standards, with a NIST 
standard reference photometer (SRP) or calibration photometers used by 
other agencies or laboratories.
    4.5.2.5 Ozone losses. Some portion of the O3 may be lost 
upon contact with the photometer cell walls and gas handling components. 
The magnitude of this loss must be determined and used to correct the 
calculated O3 concentration. This loss must not exceed 5%. 
Some guidelines for quantitatively determining this loss are discussed 
in Reference 13.
    4.5.3 Assay of O3 concentrations. The operator must carry 
out the following steps to properly assay O3 concentrations.
    4.5.3.1 Allow the photometer system to warm up and stabilize.
    4.5.3.2 Verify that the flow rate through the photometer absorption 
cell, F, allows the cell to be flushed in a reasonably short period of 
time (2 liter/min is a typical flow). The precision of the measurements 
is inversely related to the time required for flushing, since the 
photometer drift error increases with time.
    4.5.3.3 Ensure that the flow rate into the output manifold is at 
least 1 liter/min greater than the total flow rate required by the 
photometer and any other flow demand connected to the manifold.
    4.5.3.4 Ensure that the flow rate of zero air, Fz, is at least 1 
liter/min greater than the flow rate required by the photometer.
    4.5.3.5 With zero air flowing in the output manifold, actuate the 
two-way valve to allow the photometer to sample first the manifold zero 
air, then Fz. The two photometer readings must be equal (I = 
I0).
    Note: In some commercially available photometers, the operation of 
the two-way valve and various other operations in section 4.5.3 may be 
carried out automatically by the photometer.
    4.5.3.6 Adjust the O3 generator to produce an 
O3 concentration as needed.
    4.5.3.7 Actuate the two-way valve to allow the photometer to sample 
zero air until the absorption cell is thoroughly flushed and record the 
stable measured value of Io.
    4.5.3.8 Actuate the two-way valve to allow the photometer to sample 
the O3 concentration until the absorption cell is thoroughly 
flushed and record the stable measured value of I.
    4.5.3.9 Record the temperature and pressure of the sample in the 
photometer absorption cell. (See Reference 13 for guidance.)
    4.5.3.10 Calculate the O3 concentration from equation 4. 
An average of several determinations will provide better precision.
[GRAPHIC] [TIFF OMITTED] TR26OC15.005

Where:

[O3]OUT = O3 concentration, ppm
[alpha] = absorption coefficient of O3 at 254 nm = 308 atm-1 
          cm-1 at 0 [deg]C and 760 torr
l = optical path length, cm
T = sample temperature, K
P = sample pressure, torr
L = correction factor for O3 losses from 4.5.2.5 = (1-
          fraction of O3 lost).

[[Page 60]]

    Note: Some commercial photometers may automatically evaluate all or 
part of equation 4. It is the operator's responsibility to verify that 
all of the information required for equation 4 is obtained, either 
automatically by the photometer or manually. For ``automatic'' 
photometers which evaluate the first term of equation 4 based on a 
linear approximation, a manual correction may be required, particularly 
at higher O3 levels. See the photometer instruction manual 
and Reference 13 for guidance.
    4.5.3.11 Obtain additional O3 concentration standards as 
necessary by repeating steps 4.5.3.6 to 4.5.3.10 or by Option 1.
    4.5.4 Certification of transfer standards. A transfer standard is 
certified by relating the output of the transfer standard to one or more 
O3 calibration standards as determined according to section 
4.5.3. The exact procedure varies depending on the nature and design of 
the transfer standard. Consult Reference 12 for guidance.
    4.5.5 Calibration of ozone analyzers. Ozone analyzers must be 
calibrated as follows, using O3 standards obtained directly 
according to section 4.5.3 or by means of a certified transfer standard.
    4.5.5.1 Allow sufficient time for the O3 analyzer and the 
photometer or transfer standard to warm-up and stabilize.
    4.5.5.2 Allow the O3 analyzer to sample zero air until a 
stable response is obtained and then adjust the O3 analyzer's 
zero control. Offsetting the analyzer's zero adjustment to +5% of scale 
is recommended to facilitate observing negative zero drift (if any). 
Record the stable zero air response as ``Z''.
    4.5.5.3 Generate an O3 concentration standard of 
approximately 80% of the desired upper range limit (URL) of the 
O3 analyzer. Allow the O3 analyzer to sample this 
O3 concentration standard until a stable response is 
obtained.
    4.5.5.4 Adjust the O3 analyzer's span control to obtain 
the desired response equivalent to the calculated standard 
concentration. Record the O3 concentration and the 
corresponding analyzer response. If substantial adjustment of the span 
control is necessary, recheck the zero and span adjustments by repeating 
steps 4.5.5.2 to 4.5.5.4.
    4.5.5.5 Generate additional O3 concentration standards (a 
minimum of 5 are recommended) over the calibration scale of the 
O3 analyzer by adjusting the O3 source or by 
Option 1. For each O3 concentration standard, record the 
O3 concentration and the corresponding analyzer response.
    4.5.5.6 Plot the O3 analyzer responses (vertical or Y-
axis) versus the corresponding O3 standard concentrations 
(horizontal or X-axis). Compute the linear regression slope and 
intercept and plot the regression line to verify that no point deviates 
from this line by more than 2 percent of the maximum concentration 
tested.
    4.5.5.7 Option 1: The various O3 concentrations required 
in steps 4.5.3.11 and 4.5.5.5 may be obtained by dilution of the 
O3 concentration generated in steps 4.5.3.6 and 4.5.5.3. With 
this option, accurate flow measurements are required. The dynamic 
calibration system may be modified as shown in Figure 3 to allow for 
dilution air to be metered in downstream of the O3 generator. 
A mixing chamber between the O3 generator and the output 
manifold is also required. The flow rate through the O3 
generator (Fo) and the dilution air flow rate (FD) are measured with a 
flow or volume standard that is traceable to a NIST flow or volume 
calibration standard. Each O3 concentration generated by 
dilution is calculated from:
[GRAPHIC] [TIFF OMITTED] TR26OC15.006

Where:

[O3][min]OUT = diluted O3 
          concentration, ppm
FO = flow rate through the O3 generator, liter/min
FD = diluent air flow rate, liter/min
    Note: Additional information on calibration and pollutant standards 
is provided in Section 12 of Reference 14.
    5.0 Frequency of Calibration.
    5.1 The frequency of calibration, as well as the number of points 
necessary to establish the calibration curve, and the frequency of other 
performance checking will vary by analyzer; however, the minimum 
frequency, acceptance criteria, and subsequent actions are specified in 
Appendix D of Reference 14: Measurement Quality Objectives and 
Validation Templates. The user's quality control program shall provide 
guidelines for initial establishment of these variables and for 
subsequent alteration as operational experience is accumulated. 
Manufacturers of analyzers should include in their instruction/operation 
manuals information and guidance as to these variables and on other 
matters of operation, calibration, routine maintenance, and quality 
control.
    6.0 References.
1. E.C.Y. Inn and Y. Tanaka, ``Absorption coefficient of Ozone in the 
          Ultraviolet and Visible Regions'', J. Opt. Soc. Am., 43, 870 
          (1953).

[[Page 61]]

2. A. G. Hearn, ``Absorption of Ozone in the Ultraviolet and Visible 
          Regions of the Spectrum'', Proc. Phys. Soc. (London), 78, 932 
          (1961).
3. W. B. DeMore and O. Raper, ``Hartley Band Extinction Coefficients of 
          Ozone in the Gas Phase and in Liquid Nitrogen, Carbon 
          Monoxide, and Argon'', J. Phys. Chem., 68, 412 (1964).
4. M. Griggs, ``Absorption Coefficients of Ozone in the Ultraviolet and 
          Visible Regions'', J. Chem. Phys., 49, 857 (1968).
5. K. H. Becker, U. Schurath, and H. Seitz, ``Ozone Olefin Reactions in 
          the Gas Phase. 1. Rate Constants and Activation Energies'', 
          Int'l Jour. of Chem. Kinetics, VI, 725 (1974).
6. M. A. A. Clyne and J. A. Coxom, ``Kinetic Studies of Oxy-halogen 
          Radical Systems'', Proc. Roy. Soc., A303, 207 (1968).
7. J. W. Simons, R. J. Paur, H. A. Webster, and E. J. Bair, ``Ozone 
          Ultraviolet Photolysis. VI. The Ultraviolet Spectrum'', J. 
          Chem. Phys., 59, 1203 (1973).
8. Ollison, W.M.; Crow, W.; Spicer, C.W. ``Field testing of new-
          technology ambient air ozone monitors.'' J. Air Waste Manage. 
          Assoc., 63 (7), 855-863 (2013).
9. Parrish, D.D.; Fehsenfeld, F.C. ``Methods for gas-phase measurements 
          of ozone, ozone precursors and aerosol precursors.'' Atmos. 
          Environ., 34 (12-14), 1921-1957(2000).
10. Ridley, B.A.; Grahek, F.E.; Walega, J.G. ``A small, high-
          sensitivity, medium-response ozone detector suitable for 
          measurements from light aircraft.'' J. Atmos. Oceanic 
          Technol., 9 (2), 142-148(1992).
11. Boylan, P., Helmig, D., and Park, J.H. ``Characterization and 
          mitigation of water vapor effects in the measurement of ozone 
          by chemiluminescence with nitric oxide.'' Atmos. Meas. Tech. 
          7, 1231-1244 (2014).
12. Transfer Standards for Calibration of Ambient Air Monitoring 
          Analyzers for Ozone, EPA publication number EPA-454/B-13-004, 
          October 2013. EPA, Office of Air Quality Planning and 
          Standards, Research Triangle Park, NC 27711. [Available at 
          www.epa.gov/ttnamti1/files/ambient/qaqc/
          OzoneTransferStandardGuidance.pdf.]
13. Technical Assistance Document for the Calibration of Ambient Ozone 
          Monitors, EPA publication number EPA-600/4-79-057, September, 
          1979. [Available at www.epa.gov/ttnamti1/files/ambient/
          criteria/4-79-057.pdf.]
14. QA Handbook for Air Pollution Measurement Systems--Volume II. 
          Ambient Air Quality Monitoring Program. EPA-454/B-13-003, May 
          2013. [Available at http://www.epa.gov/ttnamti1/files/ambient/
          pm25/qa/QA-Handbook-Vol-II.pdf.]

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[GRAPHIC] [TIFF OMITTED] TR26OC15.007


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[GRAPHIC] [TIFF OMITTED] TR26OC15.008


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[GRAPHIC] [TIFF OMITTED] TR26OC15.009


[80 FR 65453, Oct. 26, 2015]



                  Sec. Appendix E to Part 50 [Reserved]



   Sec. Appendix F to Part 50--Measurement Principle and Calibration 
Procedure for the Measurement of Nitrogen Dioxide in the Atmosphere (Gas 
                        Phase Chemiluminescence)

                       Principle and Applicability

    1. Atmospheric concentrations of nitrogen dioxide (NO2) 
are measured indirectly by photometrically measuring the light 
intensity, at wavelengths greater than 600 nanometers, resulting from 
the chemiluminescent reaction of nitric oxide (NO) with ozone 
(O3). (1,2,3) NO2 is first quantitatively reduced 
to NO(4,5,6) by means of a converter. NO, which commonly exists in 
ambient air together with NO2, passes through the converter 
unchanged causing a resultant total NOX concentration equal 
to NO + NO2. A sample of the input air is also measured 
without having passed through the converted. This latter NO measurement 
is subtracted from the former measurement (NO + NO2) to yield 
the final NO2 measurement. The NO and NO + NO2 
measurements may be made concurrently with dual systems, or cyclically 
with the same system provided the cycle time does not exceed 1 minute.
    2. Sampling considerations.
    2.1 Chemiluminescence NO/NOX/NO2 analyzers 
will respond to other nitrogen containing compounds, such as 
peroxyacetyl nitrate (PAN), which might be reduced to NO in the thermal 
converter. (7) Atmospheric concentrations of these potential 
interferences are generally low relative to NO2 and valid 
NO2 measurements may be obtained. In certain geographical 
areas, where the concentration of these potential interferences is known 
or suspected to be high relative to NO2, the use of an 
equivalent method for the measurement of NO2 is recommended.
    2.2 The use of integrating flasks on the sample inlet line of 
chemiluminescence NO/

[[Page 65]]

NOX/NO2 analyzers is optional and left to 
couraged. The sample residence time between the sampling point and the 
analyzer should be kept to a minimum to avoid erroneous NO2 
measurements resulting from the reaction of ambient levels of NO and 
O3 in the sampling system.
    2.3 The use of particulate filters on the sample inlet line of 
chemiluminescence NO/NOX/NO2 analyzers is optional 
and left to the discretion of the user or the manufacturer.
Use of the filter should depend on the analyzer's susceptibility to 
interference, malfunction, or damage due to particulates. Users are 
cautioned that particulate matter concentrated on a filter may cause 
erroneous NO2 measurements and therefore filters should be 
changed frequently.
    3. An analyzer based on this principle will be considered a 
reference method only if it has been designated as a reference method in 
accordance with part 53 of this chapter.

                               Calibration

    1. Alternative A--Gas phase titration (GPT) of an NO standard with 
O3.
    Major equipment required: Stable O3 generator. 
Chemiluminescence NO/NOX/NO2 analyzer with strip 
chart recorder(s). NO concentration standard.
    1.1 Principle. This calibration technique is based upon the rapid 
gas phase reaction between NO and O3 to produce 
stoichiometric quantities of NO2 in accordance with the 
following equation: (8)
[GRAPHIC] [TIFF OMITTED] TC08NO91.075

The quantitative nature of this reaction is such that when the NO 
concentration is known, the concentration of NO2 can be 
determined. Ozone is added to excess NO in a dynamic calibration system, 
and the NO channel of the chemiluminescence NO/NOX/
NO2 analyzer is used as an indicator of changes in NO 
concentration. Upon the addition of O3, the decrease in NO 
concentration observed on the calibrated NO channel is equivalent to the 
concentration of NO2 produced. The amount of NO2 
generated may be varied by adding variable amounts of O3 from 
a stable uncalibrated O3 generator. (9)
    1.2 Apparatus. Figure 1, a schematic of a typical GPT apparatus, 
shows the suggested configuration of the components listed below. All 
connections between components in the calibration system downstream from 
the O3 generator should be of glass, Teflon [supreg], or 
other non-reactive material.
    1.2.1 Air flow controllers. Devices capable of maintaining constant 
air flows within 2% of the required flowrate.
    1.2.2 NO flow controller. A device capable of maintaining constant 
NO flows within 2% of the required flowrate. 
Component parts in contact with the NO should be of a non-reactive 
material.
    1.2.3 Air flowmeters. Calibrated flowmeters capable of measuring and 
monitoring air flowrates with an accuracy of 2% of 
the measured flowrate.
    1.2.4 NO flowmeter. A calibrated flowmeter capable of measuring and 
monitoring NO flowrates with an accuracy of 2% of 
the measured flowrate. (Rotameters have been reported to operate 
unreliably when measuring low NO flows and are not recommended.)
    1.2.5 Pressure regulator for standard NO cylinder. This regulator 
must have a nonreactive diaphragm and internal parts and a suitable 
delivery pressure.
    1.2.6 Ozone generator. The generator must be capable of generating 
sufficient and stable levels of O3 for reaction with NO to 
generate NO2 concentrations in the range required. Ozone 
generators of the electric discharge type may produce NO and 
NO2 and are not recommended.
    1.2.7 Valve. A valve may be used as shown in Figure 1 to divert the 
NO flow when zero air is required at the manifold. The valve should be 
constructed of glass, Teflon [supreg], or other nonreactive material.
    1.2.8 Reaction chamber. A chamber, constructed of glass, Teflon 
[supreg], or other nonreactive material, for the quantitative reaction 
of O3 with excess NO. The chamber should be of sufficient 
volume (VRC) such that the residence time (tR) meets the 
requirements specified in 1.4. For practical reasons, tR should be less 
than 2 minutes.
    1.2.9 Mixing chamber. A chamber constructed of glass, Teflon 
[supreg], or other nonreactive material and designed to provide thorough 
mixing of reaction products and diluent air. The residence time is not 
critical when the dynamic parameter specification given in 1.4 is met.
    1.2.10 Output manifold. The output manifold should be constructed of 
glass, Teflon [supreg], or other non-reactive material and should be of 
sufficient diameter to insure an insignificant pressure drop at the 
analyzer connection. The system must have a vent designed to insure 
atmospheric pressure at the manifold and to prevent ambient air from 
entering the manifold.
    1.3 Reagents.
    1.3.1 NO concentration standard. Gas cylinder standard containing 50 
to 100 ppm NO in N2 with less than 1 ppm NO2. This 
standard must be traceable to a National Bureau of Standards (NBS) NO in 
N2 Standard Reference Material (SRM 1683 or SRM 1684), an NBS 
NO2 Standard Reference Material (SRM 1629), or an NBS/EPA-
approved commercially available Certified Reference Material (CRM). 
CRM's are described in Reference 14, and a list of CRM sources is 
available from the address shown for Reference 14. A recommended 
protocol for certifying NO gas cylinders against either an NO SRM or CRM

[[Page 66]]

is given in section 2.0.7 of Reference 15. Reference 13 gives procedures 
for certifying an NO gas cylinder against an NBS NO2 SRM and 
for determining the amount of NO2 impurity in an NO cylinder.
    1.3.2 Zero air. Air, free of contaminants which will cause a 
detectable response on the NO/NOX/NO2 analyzer or 
which might react with either NO, O3, or NO2 in 
the gas phase titration. A procedure for generating zero air is given in 
reference 13.
    1.4 Dynamic parameter specification.
    1.4.1 The O3 generator air flowrate (F0) and 
NO flowrate (FNO) (see Figure 1) must be adjusted such that 
the following relationship holds:
[GRAPHIC] [TIFF OMITTED] TC08NO91.076

[GRAPHIC] [TIFF OMITTED] TC08NO91.077

[GRAPHIC] [TIFF OMITTED] TC08NO91.078

where:

PR = dynamic parameter specification, determined empirically, to insure 
          complete reaction of the available O3, ppm-minute
[NO]RC = NO concentration in the reaction chamber, ppm
R = residence time of the reactant gases in the reaction chamber, minute
[NO]STD = concentration of the undiluted NO standard, ppm
FNO = NO flowrate, scm\3\/min
FO = O3 generator air flowrate, scm\3\/min
VRC = volume of the reaction chamber, scm\3\

    1.4.2 The flow conditions to be used in the GPT system are 
determined by the following procedure:
    (a) Determine FT, the total flow required at the output manifold (FT 
= analyzer demand plus 10 to 50% excess).
    (b) Establish [NO]OUT as the highest NO concentration 
(ppm) which will be required at the output manifold. [NO]OUT 
should be approximately equivalent to 90% of the upper range limit (URL) 
of the NO2 concentration range to be covered.
    (c) Determine FNO as
    [GRAPHIC] [TIFF OMITTED] TC08NO91.079
    
    (d) Select a convenient or available reaction chamber volume. 
Initially, a trial VRC may be selected to be in the range of 
approximately 200 to 500 scm\3\.
    (e) Compute FO as
    
    
    (f) Compute tR as
    [GRAPHIC] [TIFF OMITTED] TC08NO91.080
    
Verify that tR <2 minutes. If not, select a reaction chamber with a 
smaller VRC.
    (g) Compute the diluent air flowrate as
    [GRAPHIC] [TIFF OMITTED] TC08NO91.081
    
where:

FD = diluent air flowrate, scm\3\/min

    (h) If FO turns out to be impractical for the desired system, select 
a reaction chamber having a different VRC and recompute FO and FD.

    Note: A dynamic parameter lower than 2.75 ppm-minutes may be used if 
it can be determined empirically that quantitative reaction of 
O3 with NO occurs. A procedure for making this determination 
as well as a more detailed discussion of the above requirements and 
other related considerations is given in reference 13.

    1.5 Procedure.
    1.5.1 Assemble a dynamic calibration system such as the one shown in 
Figure 1.
    1.5.2 Insure that all flowmeters are calibrated under the conditions 
of use against a reliable standard such as a soap-bubble meter or wet-
test meter. All volumetric flowrates should be corrected to 25 [deg]C 
and 760 mm Hg. A discussion on the calibration of flowmeters is given in 
reference 13.
    1.5.3 Precautions must be taken to remove O2 and other 
contaminants from the NO pressure regulator and delivery system prior to 
the start of calibration to avoid any conversion of the standard NO to 
NO2. Failure to do so can cause significant errors in 
calibration. This problem may be minimized by (1) carefully evacuating 
the regulator, when possible, after the regulator has been connected to 
the cylinder and before opening the cylinder valve; (2) thoroughly 
flushing the regulator and delivery system with NO after opening the 
cylinder valve; (3) not removing the regulator from the cylinder between 
calibrations unless absolutely necessary. Further discussion of these 
procedures is given in reference 13.
    1.5.4 Select the operating range of the NO/NOX/
NO2 analyzer to be calibrated. In order to obtain maximum 
precision and accuracy for NO2 calibration, all three 
channels of the analyzer should be set to the same range. If operation 
of the NO and NOX channels on

[[Page 67]]

higher ranges is desired, subsequent recalibration of the NO and 
NOX channels on the higher ranges is recommended.

    Note: Some analyzer designs may require identical ranges for NO, 
NOX, and NO2 during operation of the analyzer.

    1.5.5 Connect the recorder output cable(s) of the NO/NOX/
NO2 analyzer to the input terminals of the strip chart 
recorder(s). All adjustments to the analyzer should be performed based 
on the appropriate strip chart readings. References to analyzer 
responses in the procedures given below refer to recorder responses.
    1.5.6 Determine the GPT flow conditions required to meet the dynamic 
parameter specification as indicated in 1.4.
    1.5.7 Adjust the diluent air and O3 generator air flows 
to obtain the flows determined in section 1.4.2. The total air flow must 
exceed the total demand of the analyzer(s) connected to the output 
manifold to insure that no ambient air is pulled into the manifold vent. 
Allow the analyzer to sample zero air until stable NO, NOX, 
and NO2 responses are obtained. After the responses have 
stabilized, adjust the analyzer zero control(s).

    Note: Some analyzers may have separate zero controls for NO, 
NOX, and NO2. Other analyzers may have separate 
zero controls only for NO and NOX, while still others may 
have only one zero control common to all three channels.

    Offsetting the analyzer zero adjustments to + 5 percent of scale is 
recommended to facilitate observing negative zero drift. Record the 
stable zero air responses as ZNO, Znox, and Zno2.
    1.5.8 Preparation of NO and NOX calibration curves.
    1.5.8.1 Adjustment of NO span control. Adjust the NO flow from the 
standard NO cylinder to generate an NO concentration of approximately 80 
percent of the upper range limit (URL) of the NO range. This exact NO 
concentration is calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.044

where:

[NO]OUT = diluted NO concentration at the output manifold, ppm

Sample this NO concentration until the NO and NOX responses 
have stabilized. Adjust the NO span control to obtain a recorder 
response as indicated below:

recorder response (percent scale) =
[GRAPHIC] [TIFF OMITTED] TR31AU93.045

where:

URL = nominal upper range limit of the NO channel, ppm

    Note: Some analyzers may have separate span controls for NO, 
NOX, and NO2. Other analyzers may have separate 
span controls only for NO and NOX, while still others may 
have only one span control common to all three channels. When only one 
span control is available, the span adjustment is made on the NO channel 
of the analyzer.

If substantial adjustment of the NO span control is necessary, it may be 
necessary to recheck the zero and span adjustments by repeating steps 
1.5.7 and 1.5.8.1. Record the NO concentration and the analyzer's NO 
response.
    1.5.8.2 Adjustment of NOX span control. When adjusting 
the analyzer's NOX span control, the presence of any 
NO2 impurity in the standard NO cylinder must be taken into 
account. Procedures for determining the amount of NO2 
impurity in the standard NO cylinder are given in reference 13. The 
exact NOX concentration is calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.046

where:

[NOX]OUT = diluted NOX concentration at 
          the output manifold, ppm
[NO2]IMP = concentration of NO2 
          impurity in the standard NO cylinder, ppm

Adjust the NOX span control to obtain a recorder response as 
indicated below:

recorder response (% scale) =
[GRAPHIC] [TIFF OMITTED] TR31AU93.047

    Note: If the analyzer has only one span control, the span adjustment 
is made on the NO channel and no further adjustment is made here for 
NOX.

If substantial adjustment of the NOX span control is 
necessary, it may be necessary to recheck the zero and span adjustments 
by repeating steps 1.5.7 and 1.5.8.2. Record the NOX 
concentration and the analyzer's NOX response.
    1.5.8.3 Generate several additional concentrations (at least five 
evenly spaced points across the remaining scale are suggested to verify 
linearity) by decreasing FNO or increasing FD. For 
each concentration generated, calculate the exact NO and NOX 
concentrations using equations (9) and (11) respectively. Record the 
analyzer's NO and NOX responses for each concentration. Plot 
the analyzer responses versus the respective calculated NO and 
NOX concentrations and draw or calculate the NO and 
NOX calibration curves. For subsequent calibrations

[[Page 68]]

where linearity can be assumed, these curves may be checked with a two-
point calibration consisting of a zero air point and NO and 
NOX concentrations of approximately 80% of the URL.
    1.5.9 Preparation of NO2 calibration curve.
    1.5.9.1 Assuming the NO2 zero has been properly adjusted 
while sampling zero air in step 1.5.7, adjust FO and 
FD as determined in section 1.4.2. Adjust FNO to 
generate an NO concentration near 90% of the URL of the NO range. Sample 
this NO concentration until the NO and NOX responses have 
stabilized. Using the NO calibration curve obtained in section 1.5.8, 
measure and record the NO concentration as [NO]orig. Using 
the NOX calibration curve obtained in section 1.5.8, measure 
and record the NOX concentration as 
[NOX]orig.
    1.5.9.2 Adjust the O3 generator to generate sufficient 
O3 to produce a decrease in the NO concentration equivalent 
to approximately 80% of the URL of the NO2 range. The 
decrease must not exceed 90% of the NO concentration determined in step 
1.5.9.1. After the analyzer responses have stabilized, record the 
resultant NO and NOX concentrations as [NO]rem and 
[NOX]rem.
    1.5.9.3 Calculate the resulting NO2 concentration from:
    [GRAPHIC] [TIFF OMITTED] TC08NO91.082
    
where:

[NO2]OUT = diluted NO2 concentration at 
          the output manifold, ppm
[NO]orig = original NO concentration, prior to addition of 
          O3, ppm
[NO]rem = NO concentration remaining after addition of 
          O3, ppm

Adjust the NO2 span control to obtain a recorder response as 
indicated below:

recorder response (% scale) =
[GRAPHIC] [TIFF OMITTED] TR31AU93.048

    Note: If the analyzer has only one or two span controls, the span 
adjustments are made on the NO channel or NO and NOX channels 
and no further adjustment is made here for NO2.

If substantial adjustment of the NO2 span control is 
necessary, it may be necessary to recheck the zero and span adjustments 
by repeating steps 1.5.7 and 1.5.9.3. Record the NO2 
concentration and the corresponding analyzer NO2 and 
NOX responses.
    1.5.9.4 Maintaining the same FNO, FO, and 
FD as in section 1.5.9.1, adjust the ozone generator to 
obtain several other concentrations of NO2 over the 
NO2 range (at least five evenly spaced points across the 
remaining scale are suggested). Calculate each NO2 
concentration using equation (13) and record the corresponding analyzer 
NO2 and NOX responses. Plot the analyzer's 
NO2 responses versus the corresponding calculated 
NO2 concentrations and draw or calculate the NO2 
calibration curve.
    1.5.10 Determination of converter efficiency.
    1.5.10.1 For each NO2 concentration generated during the 
preparation of the NO2 calibration curve (see section 1.5.9) 
calculate the concentration of NO2 converted from:
[GRAPHIC] [TIFF OMITTED] TC08NO91.083

where:

[NO2]CONV = concentration of NO2 
          converted, ppm
[NOX]orig = original NOX concentration 
          prior to addition of O3, ppm
[NOX]rem = NOX concentration remaining 
          after addition of O3, ppm

    Note: Supplemental information on calibration and other procedures 
in this method are given in reference 13.

Plot [NO2]CONV (y-axis) versus 
[NO2]OUT (x-axis) and draw or calculate the 
converter efficiency curve. The slope of the curve times 100 is the 
average converter efficiency, EC The average converter 
efficiency must be greater than 96%; if it is less than 96%, replace or 
service the converter.
    2. Alternative B--NO2 permeation device.
    Major equipment required:
    Stable O3 generator.
    Chemiluminescence NO/NOX/NO2 analyzer with strip chart 
recorder(s).
    NO concentration standard.
    NO2 concentration standard.

[[Page 69]]

    2.1 Principle. Atmospheres containing accurately known 
concentrations of nitrogen dioxide are generated by means of a 
permeation device. (10) The permeation device emits NO2 at a 
known constant rate provided the temperature of the device is held 
constant (0.1 [deg]C) and the device has been 
accurately calibrated at the temperature of use. The NO2 
emitted from the device is diluted with zero air to produce 
NO2 concentrations suitable for calibration of the 
NO2 channel of the NO/NOX/NO2 analyzer. An NO 
concentration standard is used for calibration of the NO and NOX 
channels of the analyzer.
    2.2 Apparatus. A typical system suitable for generating the required 
NO and NO2 concentrations is shown in Figure 2. All 
connections between components downstream from the permeation device 
should be of glass, Teflon [supreg], or other non-reactive material.
    2.2.1 Air flow controllers. Devices capable of maintaining constant 
air flows within 2% of the required flowrate.
    2.2.2 NO flow controller. A device capable of maintaining constant 
NO flows within 2% of the required flowrate. 
Component parts in contact with the NO must be of a non-reactive 
material.
    2.2.3 Air flowmeters. Calibrated flowmeters capable of measuring and 
monitoring air flowrates with an accuracy of 2% of 
the measured flowrate.
    2.2.4 NO flowmeter. A calibrated flowmeter capable of measuring and 
monitoring NO flowrates with an accuracy of 2% of 
the measured flowrate. (Rotameters have been reported to operate 
unreliably when measuring low NO flows and are not recommended.)
    2.2.5 Pressure regulator for standard NO cylinder. This regulator 
must have a non-reactive diaphragm and internal parts and a suitable 
delivery pressure.
    2.2.6 Drier. Scrubber to remove moisture from the permeation device 
air system. The use of the drier is optional with NO2 
permeation devices not sensitive to moisture. (Refer to the supplier's 
instructions for use of the permeation device.)
    2.2.7 Constant temperature chamber. Chamber capable of housing the 
NO2 permeation device and maintaining its temperature to 
within 0.1 [deg]C.
    2.2.8 Temperature measuring device. Device capable of measuring and 
monitoring the temperature of the NO2 permeation device with 
an accuracy of 0.05 [deg]C.
    2.2.9 Valves. A valve may be used as shown in Figure 2 to divert the 
NO2 from the permeation device when zero air or NO is 
required at the manifold. A second valve may be used to divert the NO 
flow when zero air or NO2 is required at the manifold.
    The valves should be constructed of glass, Teflon [supreg], or other 
nonreactive material.
    2.2.10 Mixing chamber. A chamber constructed of glass, Teflon 
[supreg], or other nonreactive material and designed to provide thorough 
mixing of pollutant gas streams and diluent air.
    2.2.11 Output manifold. The output manifold should be constructed of 
glass, Teflon [supreg], or other non-reactive material and should be of 
sufficient diameter to insure an insignificant pressure drop at the 
analyzer connection. The system must have a vent designed to insure 
atmospheric pressure at the manifold and to prevent ambient air from 
entering the manifold.
    2.3 Reagents.
    2.3.1 Calibration standards. Calibration standards are required for 
both NO and NO2. The reference standard for the calibration 
may be either an NO or NO2 standard, and must be traceable to 
a National Bureau of Standards (NBS) NO in N2 Standard 
Reference Material (SRM 1683 or SRM 1684), and NBS NO2 
Standard Reference Material (SRM 1629), or an NBS/EPA-approved 
commercially available Certified Reference Material (CRM). CRM's are 
described in Reference 14, and a list of CRM sources is available from 
the address shown for Reference 14. Reference 15 gives recommended 
procedures for certifying an NO gas cylinder against an NO SRM or CRM 
and for certifying an NO2 permeation device against an 
NO2 SRM. Reference 13 contains procedures for certifying an 
NO gas cylinder against an NO2 SRM and for certifying an 
NO2 permeation device against an NO SRM or CRM. A procedure 
for determining the amount of NO2 impurity in an NO cylinder 
is also contained in Reference 13. The NO or NO2 standard 
selected as the reference standard must be used to certify the other 
standard to ensure consistency between the two standards.
    2.3.1.1 NO2 Concentration standard. A permeation device 
suitable for generating NO2 concentrations at the required 
flow-rates over the required concentration range. If the permeation 
device is used as the reference standard, it must be traceable to an SRM 
or CRM as specified in 2.3.1. If an NO cylinder is used as the reference 
standard, the NO2 permeation device must be certified against 
the NO standard according to the procedure given in Reference 13. The 
use of the permeation device should be in strict accordance with the 
instructions supplied with the device. Additional information regarding 
the use of permeation devices is given by Scaringelli et al. (11) and 
Rook et al. (12).
    2.3.1.2 NO Concentration standard. Gas cylinder containing 50 to 100 
ppm NO in N2 with less than 1 ppm NO2. If this 
cylinder is used as the reference standard, the cylinder must be 
traceable to an SRM or CRM as specified in 2.3.1. If an NO2 
permeation device is used as the reference standard, the NO cylinder 
must be certified against the NO2 standard according to the 
procedure given in Reference 13. The cylinder should be recertified

[[Page 70]]

on a regular basis as determined by the local quality control program.
    2.3.3 Zero air. Air, free of contaminants which might react with NO 
or NO2 or cause a detectable response on the NO/NOX/
NO2 analyzer. When using permeation devices that are 
sensitive to moisture, the zero air passing across the permeation device 
must be dry to avoid surface reactions on the device. (Refer to the 
supplier's instructions for use of the permeation device.) A procedure 
for generating zero air is given in reference 13.
    2.4 Procedure.
    2.4.1 Assemble the calibration apparatus such as the typical one 
shown in Figure 2.
    2.4.2 Insure that all flowmeters are calibrated under the conditions 
of use against a reliable standard such as a soap bubble meter or wet-
test meter. All volumetric flowrates should be corrected to 25 [deg]C 
and 760 mm Hg. A discussion on the calibration of flowmeters is given in 
reference 13.
    2.4.3 Install the permeation device in the constant temperature 
chamber. Provide a small fixed air flow (200-400 scm\3\/min) across the 
device. The permeation device should always have a continuous air flow 
across it to prevent large buildup of NO2 in the system and a 
consequent restabilization period. Record the flowrate as FP. Allow the 
device to stabilize at the calibration temperature for at least 24 
hours. The temperature must be adjusted and controlled to within 0.1 [deg]C or less of the calibration temperature as 
monitored with the temperature measuring device.
    2.4.4 Precautions must be taken to remove O2 and other 
contaminants from the NO pressure regulator and delivery system prior to 
the start of calibration to avoid any conversion of the standard NO to 
NO2. Failure to do so can cause significant errors in 
calibration. This problem may be minimized by
    (1) Carefully evacuating the regulator, when possible, after the 
regulator has been connected to the cylinder and before opening the 
cylinder valve;
    (2) Thoroughly flushing the regulator and delivery system with NO 
after opening the cylinder valve;
    (3) Not removing the regulator from the cylinder between 
calibrations unless absolutely necessary. Further discussion of these 
procedures is given in reference 13.
    2.4.5 Select the operating range of the NO/NOX NO2 
analyzer to be calibrated. In order to obtain maximum precision and 
accuracy for NO2 calibration, all three channels of the 
analyzer should be set to the same range. If operation of the NO and NOX 
channels on higher ranges is desired, subsequent recalibration of the NO 
and NOX channels on the higher ranges is recommended.

    Note: Some analyzer designs may require identical ranges for NO, 
NOX, and NO2 during operation of the analyzer.

    2.4.6 Connect the recorder output cable(s) of the NO/NOX/
NO2 analyzer to the input terminals of the strip chart 
recorder(s). All adjustments to the analyzer should be performed based 
on the appropriate strip chart readings. References to analyzer 
responses in the procedures given below refer to recorder responses.
    2.4.7 Switch the valve to vent the flow from the permeation device 
and adjust the diluent air flowrate, FD, to provide zero air at the 
output manifold. The total air flow must exceed the total demand of the 
analyzer(s) connected to the output manifold to insure that no ambient 
air is pulled into the manifold vent. Allow the analyzer to sample zero 
air until stable NO, NOX, and NO2 responses are obtained. 
After the responses have stabilized, adjust the analyzer zero 
control(s).

    Note: Some analyzers may have separate zero controls for NO, NOX, 
and NO2. Other analyzers may have separate zero controls only 
for NO and NOX, while still others may have only one zero common control 
to all three channels.

Offsetting the analyzer zero adjustments to + 5% of scale is recommended 
to facilitate observing negative zero drift. Record the stable zero air 
responses as ZNO, ZNOX, and 
ZNO2.
    2.4.8 Preparation of NO and NOX calibration curves.
    2.4.8.1 Adjustment of NO span control. Adjust the NO flow from the 
standard NO cylinder to generate an NO concentration of approximately 
80% of the upper range limit (URL) of the NO range. The exact NO 
concentration is calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.049

where:

[NO]OUT = diluted NO concentration at the output manifold, 
          ppm
FNO = NO flowrate, scm\3\/min
[NO]STD = concentration of the undiluted NO standard, ppm
FD = diluent air flowrate, scm\3\/min

Sample this NO concentration until the NO and NOX responses have 
stabilized. Adjust the NO span control to obtain a recorder response as 
indicated below:

recorder response (% scale) =
[GRAPHIC] [TIFF OMITTED] TR31AU93.050

[GRAPHIC] [TIFF OMITTED] TR31AU93.051

where:


[[Page 71]]


URL = nominal upper range limit of the NO channel, ppm

    Note: Some analyzers may have separate span controls for NO, NOX, 
and NO2. Other analyzers may have separate span controls only 
for NO and NOX, while still others may have only one span control common 
to all three channels. When only one span control is available, the span 
adjustment is made on the NO channel of the analyzer.

If substantial adjustment of the NO span control is necessary, it may be 
necessary to recheck the zero and span adjustments by repeating steps 
2.4.7 and 2.4.8.1. Record the NO concentration and the analyzer's NO 
response.
    2.4.8.2 Adjustment of NOX span control. When adjusting the 
analyzer's NOX span control, the presence of any NO2 impurity 
in the standard NO cylinder must be taken into account. Procedures for 
determining the amount of NO2 impurity in the standard NO 
cylinder are given in reference 13. The exact NOX concentration is 
calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.052

where:

[NOX]OUT = diluted NOX cencentration at 
          the output manifold, ppm
[NO2]IMP = concentration of NO2 
          impurity in the standard NO cylinder, ppm

Adjust the NOX span control to obtain a convenient recorder response as 
indicated below:

recorder response (% scale)
[GRAPHIC] [TIFF OMITTED] TR31AU93.053

    Note: If the analyzer has only one span control, the span adjustment 
is made on the NO channel and no further adjustment is made here for 
NOX.

If substantial adjustment of the NOX span control is 
necessary, it may be necessary to recheck the zero and span adjustments 
by repeating steps 2.4.7 and 2.4.8.2. Record the NOX 
concentration and the analyzer's NOX response.
    2.4.8.3 Generate several additional concentrations (at least five 
evenly spaced points across the remaining scale are suggested to verify 
linearity) by decreasing FNO or increasing FD. For each 
concentration generated, calculate the exact NO and NOX 
concentrations using equations (16) and (18) respectively. Record the 
analyzer's NO and NOX responses for each concentration. Plot 
the analyzer responses versus the respective calculated NO and 
NOX concentrations and draw or calculate the NO and 
NOX calibration curves. For subsequent calibrations where 
linearity can be assumed, these curves may be checked with a two-point 
calibration consisting of a zero point and NO and NOX 
concentrations of approximately 80 percent of the URL.
    2.4.9 Preparation of NO2 calibration curve.
    2.4.9.1 Remove the NO flow. Assuming the NO2 zero has 
been properly adjusted while sampling zero air in step 2.4.7, switch the 
valve to provide NO2 at the output manifold.
    2.4.9.2 Adjust FD to generate an NO2 concentration of 
approximately 80 percent of the URL of the NO2 range. The 
total air flow must exceed the demand of the analyzer(s) under 
calibration. The actual concentration of NO2 is calculated 
from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.054

where:

[NO2]OUT = diluted NO2 concentration at 
          the output manifold, ppm
R = permeation rate, [micro]g/min
K = 0.532 [micro]l NO2/[micro]g NO2 (at 25 [deg]C 
          and 760 mm Hg)
Fp = air flowrate across permeation device, scm\3\/min
FD = diluent air flowrate, scm\3\/min

Sample this NO2 concentration until the NOX and 
NO2 responses have stabilized. Adjust the NO2 span 
control to obtain a recorder response as indicated below:

recorder response (% scale)
[GRAPHIC] [TIFF OMITTED] TR31AU93.055

    Note: If the analyzer has only one or two span controls, the span 
adjustments are made on the NO channel or NO and NOX channels 
and no further adjustment is made here for NO2.

If substantial adjustment of the NO2 span control is 
necessary it may be necessary to recheck the zero and span adjustments 
by repeating steps 2.4.7 and 2.4.9.2. Record the NO2 
concentration and the analyzer's NO2 response. Using the 
NOX calibration curve obtained in step 2.4.8, measure and 
record the NOX concentration as [NOX]M.
    2.4.9.3 Adjust FD to obtain several other concentrations of 
NO2 over the NO2 range (at least five evenly 
spaced points across the remaining scale are suggested). Calculate each 
NO2 concentration using equation (20) and record the 
corresponding analyzer NO2 and NOX responses. Plot 
the analyzer's NO2 responses versus the corresponding 
calculated NO2 concentrations and draw or calculate the 
NO2 calibration curve.
    2.4.10 Determination of converter efficiency.
    2.4.10.1 Plot [NOX]M (y-axis) versus 
[NO2]OUT (x-axis) and draw or calculate the 
converter efficiency curve. The slope of the curve times 100 is the 
average converter efficiency,

[[Page 72]]

EC. The average converter efficiency must be greater than 96 percent; if 
it is less than 96 percent, replace or service the converter.

    Note: Supplemental information on calibration and other procedures 
in this method are given in reference 13.

    3. Frequency of calibration. The frequency of calibration, as well 
as the number of points necessary to establish the calibration curve and 
the frequency of other performance checks, will vary from one analyzer 
to another. The user's quality control program should provide guidelines 
for initial establishment of these variables and for subsequent 
alteration as operational experience is accumulated. Manufacturers of 
analyzers should include in their instruction/operation manuals 
information and guidance as to these variables and on other matters of 
operation, calibration, and quality control.

                               References

    1. A. Fontijn, A. J. Sabadell, and R. J. Ronco, ``Homogeneous 
Chemiluminescent Measurement of Nitric Oxide with Ozone,'' Anal. Chem., 
42, 575 (1970).
    2. D. H. Stedman, E. E. Daby, F. Stuhl, and H. Niki, ``Analysis of 
Ozone and Nitric Oxide by a Chemiluminiscent Method in Laboratory and 
Atmospheric Studies of Photochemical Smog,'' J. Air Poll. Control 
Assoc., 22, 260 (1972).
    3. B. E. Martin, J. A. Hodgeson, and R. K. Stevens, ``Detection of 
Nitric Oxide Chemiluminescence at Atmospheric Pressure,'' Presented at 
164th National ACS Meeting, New York City, August 1972.
    4. J. A. Hodgeson, K. A. Rehme, B. E. Martin, and R. K. Stevens, 
``Measurements for Atmospheric Oxides of Nitrogen and Ammonia by 
Chemiluminescence,'' Presented at 1972 APCA Meeting, Miami, FL, June 
1972.
    5. R. K. Stevens and J. A. Hodgeson, ``Applications of 
Chemiluminescence Reactions to the Measurement of Air Pollutants,'' 
Anal. Chem., 45, 443A (1973).
    6. L. P. Breitenbach and M. Shelef, ``Development of a Method for 
the Analysis of NO2 and NH3 by NO-Measuring 
Instruments,'' J. Air Poll. Control Assoc., 23, 128 (1973).
    7. A. M. Winer, J. W. Peters, J. P. Smith, and J. N. Pitts, Jr., 
``Response of Commercial Chemiluminescent NO-NO2 Analyzers to 
Other Nitrogen-Containing Compounds,'' Environ. Sci. Technol., 8, 1118 
(1974).
    8. K. A. Rehme, B. E. Martin, and J. A. Hodgeson, Tentative Method 
for the Calibration of Nitric Oxide, Nitrogen Dioxide, and Ozone 
Analyzers by Gas Phase Titration,'' EPA-R2-73-246, March 1974.
    9. J. A. Hodgeson, R. K. Stevens, and B. E. Martin, ``A Stable Ozone 
Source Applicable as a Secondary Standard for Calibration of Atmospheric 
Monitors,'' ISA Transactions, 11, 161 (1972).
    10. A. E. O'Keeffe and G. C. Ortman, ``Primary Standards for Trace 
Gas Analysis,'' Anal. Chem., 38, 760 (1966).
    11. F. P. Scaringelli, A. E. O'Keeffe, E. Rosenberg, and J. P. Bell, 
``Preparation of Known Concentrations of Gases and Vapors with 
Permeation Devices Calibrated Gravimetrically,'' Anal. Chem., 42, 871 
(1970).
    12. H. L. Rook, E. E. Hughes, R. S. Fuerst, and J. H. Margeson, 
``Operation Characteristics of NO2 Permeation Devices,'' 
Presented at 167th National ACS Meeting, Los Angeles, CA, April 1974.
    13. E. C. Ellis, ``Technical Assistance Document for the 
Chemiluminescence Measurement of Nitrogen Dioxide,'' EPA-E600/4-75-003 
(Available in draft form from the United States Environmental Protection 
Agency, Department E (MD-76), Environmental Monitoring and Support 
Laboratory, Research Triangle Park, NC 27711).
    14. A Procedure for Establishing Traceability of Gas Mixtures to 
Certain National Bureau of Standards Standard Reference Materials. EPA-
600/7-81-010, Joint publication by NBS and EPA. Available from the U.S. 
Environmental Protection Agency, Environmental Monitoring Systems 
Laboratory (MD-77), Research Triangle Park, NC 27711, May 1981.
    15. Quality Assurance Handbook for Air Pollution Measurement 
Systems, Volume II, Ambient Air Specific Methods. The U.S. Environmental 
Protection Agency, Environmental Monitoring Systems Laboratory, Research 
Triangle Park, NC 27711. Publication No. EAP-600/4-77-027a.

[[Page 73]]






[41 FR 52688, Dec. 1, 1976, as amended at 48 FR 2529, Jan. 20, 1983]

[[Page 74]]



 Sec. Appendix G to Part 50--Reference Method for the Determination of 
               Lead in Total Suspended Particulate Matter

                       1.0 Scope and Applicability

    Based on review of the air quality criteria and national ambient air 
quality standard (NAAQS) for lead (Pb) completed in 2008, the EPA made 
revisions to the primary and secondary NAAQS for Pb to protect public 
health and welfare. The EPA revised the level from 1.5 [micro]g/m\3\ to 
0.15 [micro]g/m\3\ while retaining the current indicator of Pb in total 
suspended particulate matter (Pb-TSP).
    Pb-TSP is collected for 24 hours on a TSP filter as described in 
Appendix B of part 50, the Reference Method for the Determination of 
Suspended Particulate Matter in the Atmosphere (High-Volume Method). 
This method is for the analysis of Pb from TSP filters by Inductively 
Coupled Plasma Mass Spectrometry (ICP-MS) using a heated ultrasonic bath 
with nitric acid (HNO3) and hydrochloric acid (HCl) or a 
heated block (hot block) digester with HNO3 for filter 
extraction.
    This method is based on the EPA's Office of Solid Waste (SW-846) 
Method 6020A--Inductively Coupled Plasma Mass Spectrometry (U.S. EPA, 
2007). Wording in certain sections of this method is paraphrased or 
taken directly from Method 6020A.
    1.1 ICP-MS is applicable for the sub-[micro]g/mL (ppb) determination 
of Pb in a wide variety of matrices. Results reported for monitoring or 
compliance purposes are calculated in [micro]g/m\3\ at local conditions 
(LC). This procedure describes a method for the acid extraction of Pb in 
particulate matter collected on glass fiber, quartz, or PTFE filters and 
measurement of the extracted Pb using ICP-MS.
    1.2 Due to variations in the isotopic abundance of Pb, the value for 
total Pb must be based on the sum of the signal intensities for isotopic 
masses, 206, 207, and 208. Most instrument software packages are able to 
sum the primary isotope signal intensities automatically.
    1.3 ICP-MS requires the use of an internal standard. \115\In 
(Indium), \165\Ho (Holmium), and \209\Bi (Bismuth) are recommended 
internal standards for the determination of Pb.
    1.4 Use of this method is restricted to use by, or under supervision 
of, properly trained and experienced laboratory personnel. Requirements 
include training and experience in inorganic sample preparation, 
including acid extraction, and also knowledge in the recognition and in 
the correction of spectral, chemical and physical interference in ICP-
MS.

                          2.0 Summary of Method

    2.1 This method describes the acid extraction of Pb in particulate 
matter collected on glass fiber, quartz, or PTFE ambient air filters 
with subsequent measurement of Pb by ICP-MS. Estimates of the Method 
Detection Limit (MDL) or sensitivity of the method are provided in 
Tables 1, 3 and 5 and determined using Pb-spiked filters or filter 
strips analyzed in accordance with the guidance provided in 40 CFR 136, 
Appendix B--Determination and procedures for the Determination of the 
Method Detection Limit--Revision 1.1. The analytical range of the method 
is 0.00024 [micro]g/m\3\ to 0.60 [micro]g/m\3\, and based on the low and 
high calibration curve standards and a nominal filter sample volume of 
2000 m\3\.
    2.2 This method includes two extraction methods. In the first 
method, a solution of HNO3 and HCl is added to the filters or 
filter strips in plastic digestion tubes and the tubes are placed in a 
heated ultrasonic bath for one hour to facilitate the extraction of Pb. 
Following ultrasonication, the samples are brought to a final volume of 
40 mL (50 mL for PTFE filters), vortex mixed or shaken vigorously, and 
centrifuged prior to aliquots being taken for ICP-MS analysis. In the 
second method, a solution of dilute HNO3 is added to the 
filter strips in plastic digestion tubes and the tubes placed into the 
hot block digester. The filter strip is completely covered by the 
solution. The tubes are covered with polypropylene watch glasses and 
refluxed. After reflux, the samples are diluted to a final volume of 50 
mL with reagent water and mixed before analysis.
    2.3 Calibration standards and check standards are prepared to matrix 
match the acid composition of the samples. ICP-MS analysis is then 
performed. With this method, the samples are first aspirated and the 
aerosol thus created is transported by a flow of argon gas into the 
plasma torch. The ions produced (e.g., Pb+ 1) in the plasma 
are extracted via a differentially-pumped vacuum interface and are 
separated on the basis of their mass-to-charge ratio. The ions are 
quantified by a channel electron multiplier or a Faraday detector and 
the signal collected is processed by the instrument's software. 
Interferences must be assessed and corrected for, if present.

                             3.0 Definitions

Pb--Elemental or ionic lead
HNO3--Nitric acid
HCl--Hydrochloric acid
ICP-MS--Inductively Coupled Plasma Mass Spectrometer
MDL--Method detection limit
RSD--Relative standard deviation
RPD--Relative percent difference
CB--Calibration Blank
CAL--Calibration Standard
ICB--Initial calibration blank
CCB--Continuing calibration blank
ICV--Initial calibration verification
CCV--Continuing calibration verification

[[Page 75]]

LLCV--Lower Level Calibration Verification, serves as the lower level 
ICV and lower level CCV
RB--Reagent blank
RBS--Reagent blank spike
MSDS--Material Safety Data Sheet
NIST--National Institute of Standards and Technology
D.I. water--Deionized water
SRM--NIST Standard Reference Material
CRM--Certified Reference Material
EPA--Environmental Protection Agency
v/v--Volume to volume ratio

                            4.0 Interferences

    4.1 Reagents, glassware, plasticware, and other sample processing 
hardware may yield artifacts and/or interferences to sample analysis. If 
reagent blanks, filter blanks, or quality control blanks yield results 
above the detection limit, the source of contamination must be 
identified. All containers and reagents used in the processing of the 
samples must be checked for contamination prior to sample extraction and 
analysis. Reagents shall be diluted to match the final concentration of 
the extracts and analyzed for Pb. Labware shall be rinsed with dilute 
acid solution and the solution analyzed. Once a reagent or labware 
article (such as extraction tubes) from a manufacturer has been 
successfully screened, additional screening is not required unless 
contamination is suspected.
    4.2 Isobaric elemental interferences in ICP-MS are caused by 
isotopes of different elements forming atomic ions with the same nominal 
mass-to-charge ratio (m/z) as the species of interest. There are no 
species found in ambient air that will result in isobaric interference 
with the three Pb isotopes (206, 207, and 208) being measured. 
Polyatomic interferences occur when two or more elements combine to form 
an ion with the same mass-to-charge ratio as the isotope being measured. 
Pb is not subject to interference from common polyatomic ions and no 
correction is required.
    4.3 The distribution of Pb isotopes is not constant. The analysis of 
total Pb should be based on the summation of signal intensities for the 
isotopic masses 206, 207, and 208. In most cases, the instrument 
software can perform the summation automatically.
    4.4 Physical interferences are associated with the sample 
nebulization and transport processes as well as with ion-transmission 
efficiencies. Dissolved solids can deposit on the nebulizer tip of a 
pneumatic nebulizer and on the interface skimmers of the ICP-MS. 
Nebulization and transport processes can be affected if a matrix 
component causes a change in surface tension or viscosity. Changes in 
matrix composition can cause significant signal suppression or 
enhancement. These interferences are compensated for by use of internal 
standards. Sample dilution will reduce the effects of high levels of 
dissolved salts, but calibration standards must be prepared in the 
extraction medium and diluted accordingly.
    4.5 Memory interferences are related to sample transport and result 
when there is carryover from one sample to the next. Sample carryover 
can result from sample deposition on the sample and skimmer cones and 
from incomplete rinsing of the sample solution from the plasma torch and 
the spray chamber between samples. These memory effects are dependent 
upon both the analyte being measured and sample matrix and can be 
minimized through the use of suitable rinse times.

                     5.0 Health and Safety Cautions

    5.1 The toxicity or carcinogenicity of reagents used in this method 
has not been fully established. Each chemical should be regarded as a 
potential health hazard and exposure to these compounds should be as low 
as reasonably achievable. Each laboratory is responsible for maintaining 
a current file of OSHA regulations regarding the safe handling of the 
chemicals specified in this method. A reference file of material safety 
data sheets (MSDSs) should be available to all personnel involved in the 
chemical analysis. Specifically, concentrated HNO3 presents 
various hazards and is moderately toxic and extremely irritating to skin 
and mucus membranes. Use this reagent in a fume hood whenever possible 
and if eye or skin contact occurs, flush with large volumes of water. 
Always wear safety glasses or a shield for eye protection, protective 
clothing, and observe proper mixing when working with these reagents.
    5.2 Concentrated HNO3 and HCl are moderately toxic and 
extremely irritating to the skin. Use these reagents in a fume hood, and 
if eye and skin contact occurs, flush with large volumes of water. 
Always wear safety glasses or a shield for eye protection when working 
with these reagents. The component of this procedure requiring the 
greatest care is HNO3. HNO3 is a strong, 
corrosive, oxidizing agent that requires protection of the eyes, skin, 
and clothing. Items to be worn during use of this reagent include:
    1. Safety goggles (or safety glasses with side shields),
    2. Acid resistant rubber gloves, and
    3. A protective garment such as a laboratory apron. HNO3 
spilled on clothing will destroy the fabric; contact with the skin 
underneath will result in a burn.
    It is also essential that an eye wash fountain or eye wash bottle be 
available during performance of this method. An eye wash bottle has a 
spout that covers the eye. If acid or any other corrosive gets into the 
eye, the water in this bottle is squirted onto the eye to wash out the 
harmful material. Eye washing should be performed with large amounts

[[Page 76]]

of water immediately after exposure. Medical help should be sought 
immediately after washing. If either acid, but especially 
HNO3, is spilled onto the skin, wash immediately with large 
amounts of water. Medical attention is not required unless the burn 
appears to be significant. Even after washing and drying, 
HNO3 may leave the skin slightly brown in color; this will 
heal and fade with time.
    5.3 Pb salts and Pb solutions are toxic. Great care must be taken to 
ensure that samples and standards are handled properly; wash hands 
thoroughly after handling.
    5.4 Care must be taken when using the ultrasonic bath and hot block 
digester as they are capable of causing mild burns. Users should refer 
to the safety guidance provided by the manufacturer of their specific 
equipment.
    5.5 Analytical plasma sources emit radio frequency radiation in 
addition to intense ultra violet (UV) radiation. Suitable precautions 
should be taken to protect personnel from such hazards. The inductively 
coupled plasma should only be viewed with proper eye protection from UV 
emissions.

                              6.0 Equipment

    6.1 Thermo Scientific X-Series ICP-MS or equivalent. The system must 
be capable of providing resolution better or equal to 1.0 atomic mass 
unit (amu) at 10 percent peak height. The system must have a mass range 
from at least 7 to 240 amu that allows for the application of the 
internal standard technique. For the measurement of Pb, an instrument 
with a collision or reaction cell is not required.

                   6.2 Ultrasonic Extraction Equipment

    6.2.1 Heated ultrasonic bath capable of maintaining a temperature of 
80 [deg]C; VWR Model 750HT, 240W, or equivalent. Ultrasonic bath must 
meet the following performance criteria:
    1. Cut a strip of aluminum foil almost the width of the tank and 
double the depth.
    2. Turn the ultrasonic bath on and lower the foil into the bath 
vertically until almost touching the bottom of the tank and hold for 10 
seconds.
    3. Remove the foil from the tank and observe the distribution of 
perforations and small pin prick holes. The indentations should be fine 
and evenly distributed. The even distribution of indentations indicates 
the ultrasonic bath is acceptable for use.
    6.2.2 Laboratory centrifuge, Beckman GS-6, or equivalent.
    6.2.3 Vortex mixer, VWR Signature Digital Vortex Mixer, VWR Catalog 
No. 14005-824, or equivalent.
    6.3 Hot block extraction equipment
    6.3.1 Hot block digester, SCP Science DigiPrep Model MS, No. 010-
500-205 block digester capable of maintaining a temperature of 95 
[deg]C, or equivalent.
    6.4 Materials and Supplies
     Argon gas supply, 99.99 percent purity or better. 
National Welders Microbulk, or equivalent.
     Plastic digestion tubes with threaded caps for 
extraction and storage, SCP Science DigiTUBE[supreg] Item No. 010-500-
063, or equivalent.
     Disposable polypropylene ribbed watch glasses 
(for heated block extraction), SCP Science Item No. 010-500-081, or 
equivalent.
     Pipette, Rainin EDP2, 100 [micro]L, 1 percent accuracy, <=1 percent RSD (precision), with 
disposable tips, or equivalent.
     Pipette, Rainin EDP2, 1000 [micro]L, 1 percent accuracy, <=1 percent RSD (precision), with 
disposable tips, or equivalent.
     Pipette, Rainin EDP2, 1-10 mL, 1 percent accuracy, <=1 percent RSD (precision), with 
disposable tips, or equivalent.
     Pipette, Thermo Lab Systems, 5 mL, 1 percent accuracy, <=1 percent RSD (precision), with 
disposable tips, or equivalent.
     Plastic tweezer, VWR Catalog No. 89026-420, or 
equivalent.
     Laboratory marker.
     Ceramic knife, Kyocera LK-25, and non-metal ruler 
or other suitable cutting tools for making straight cuts for accurately 
measured strips.
     Blank labels or labeling tape, VWR Catalog No. 
36425-045, or equivalent.
     Graduated cylinder, 1 L, VWR 89000-260, or 
equivalent.
     Volumetric flask, Class A, 1 L, VWR Catalog No. 
89025-778, or equivalent.
     Millipore Element deionized water system, or 
equivalent, capable of generating water with a resistivity of 
=17.9 M[Omega]-cm).
     Disposable syringes, 10-mL, with 0.45 micron 
filters (must be Pb-free).
     Plastic or PTFE wash bottles.
     Glassware, Class A--volumetric flasks, pipettes, 
and graduated cylinders.
     Glass fiber, quartz, or PTFE filters from the 
same filter manufacturer and lot used for sample collection for use in 
the determination of the MDL and for laboratory blanks.

                       7.0 Reagents and Standards

    7.1 Reagent--or trace metals-grade chemicals must be used in all 
tests. Unless otherwise indicated, it is intended that all reagents 
conform to the specifications of the Committee on Analytical Reagents of 
the American Chemical Society, where such specifications are available.
    7.2 Concentrated nitric acid, 67-70 percent, SCP Science Catalog No. 
250-037-177, or equivalent.
    7.3 Concentrated hydrochloric acid (for the ultrasonic extraction 
method), 33-36 percent, SCP Science Catalog No. 250-037-175, or 
equivalent.

[[Page 77]]

    7.4 Deionized water--All references to deionized water in the method 
refer to deionized water with a resistivity =17.9 M[Omega]-
cm.
    7.5 Standard stock solutions may be commercially purchased for each 
element or as a multi-element mix. Internal standards may be purchased 
as a mixed multi-element solution. The manufacturer's expiration date 
and storage conditions must be adhered to.
    7.5.1 Lead standard, 1000 [micro]g/mL, NIST traceable, commercially 
available with certificate of analysis. High Purity Standards Catalog 
No. 100028-1, or equivalent.
    7.5.2 Indium (In) standard, 1000 [micro]g/mL, NIST traceable, 
commercially available with certificate of analysis. High Purity 
Standards Catalog No. 100024-1, or equivalent.
    7.5.3 Bismuth (Bi) standard, 1000 [micro]g/mL, NIST traceable, 
commercially available with certificate of analysis. High Purity 
Standards Catalog No. 100006-1, or equivalent.
    7.5.4 Holmium (Ho) standard, 1000 [micro]g/mL, NIST traceable, 
commercially available with certificate of analysis. High Purity 
Standards Catalog No. 100023-1, or equivalent.
    7.5.5 Second source lead standard, 1000 [micro]g/mL, NIST traceable, 
commercially available with certificate of analysis. Must be from a 
different vendor or lot than the standard described in 7.5.1. Inorganic 
Ventures Catalog No. CGPB-1, or equivalent.
    7.5.6 Standard Reference Materials, NIST SRM 2583, 2586, 2587 or 
1648, or equivalent.\5\
---------------------------------------------------------------------------

    \5\ Certificates of Analysis for these SRMs can be found at: http://
www.nist.gov/srm/index.cfm.
---------------------------------------------------------------------------

    Note: The In, Bi, and Ho internal standards may also be purchased as 
10 [micro]g/mL standards. Calibration standards are prepared by diluting 
stock standards to the appropriate levels in the same acid 
concentrations as in the final sample volume. The typical range for 
calibration standards is 0.001 to 2.00 [micro]g/mL. At a minimum, the 
curve must contain a blank and five Pb containing calibration standards. 
The calibration standards are stored at ambient laboratory temperature. 
Calibration standards must be prepared weekly and verified against a 
freshly prepared ICV using a NIST-traceable source different from the 
calibration standards.
    7.6 Internal standards may be added to the test solution or by on-
line addition. The nominal concentration for an internal standard is 
0.010 [micro]g/mL (10 ppb). Bismuth (Bi) or holmium (Ho) are the 
preferred internal standards for Pb, but indium (In) may be used in the 
event the sample contains Bi and high recoveries are observed.
    7.7 Three laboratory blank solutions are required for analysis: (1) 
The calibration blank is used in the construction of the calibration 
curve and as a periodic check of system cleanliness (ICB and CCB); (2) 
the reagent blank (RB) is carried through the extraction process to 
assess possible contamination; and (3) the rinse blank is run between 
samples to clean the sample introduction system. If RBs or laboratory 
blanks yield results above the detection limit, the source of 
contamination must be identified. Screening of labware and reagents is 
addressed in Section 4.1.
    7.7.1 The calibration blank is prepared in the same acid matrix as 
the calibration standards and samples and contains all internal 
standards used in the analysis.
    7.7.2 The RB contains all reagents used in the extraction and is 
carried through the extraction procedure at the same time as the 
samples.
    7.7.3 The rinse blank is a solution of 1 to 2 percent 
HNO3 (v/v) in reagent grade water. A sufficient volume should 
be prepared to flush the system between all standards and samples 
analyzed.
    7.7.4 The EPA currently provides glass fiber, quartz, and PTFE 
filters to air monitoring agencies as requested annually. As part of the 
procurement process, these filters are tested for acceptance by the EPA. 
The current acceptance criteria for glass fiber and quartz filters is 15 
[micro]g per filter or 0.0075 [micro]g/m\3\ using a nominal sample 
volume of 2000 m\3\ and 4.8 ng/cm\2\ or 0.0024 [micro]g/m\3\ for PTFE 
filters using a nominal sample volume of 24 m\3\. Acceptance test 
results for filters obtained by the EPA are typically well below the 
criterion specified and also below the recently revised Pb method 
performance detection limit of 0.0075 [micro]g/m\3\; therefore, blank 
subtraction should not be performed.
    7.7.5 If filters are not provided by the EPA for sample collection 
and analysis, filter lot blanks should be analyzed for Pb content. For 
large filter lots (500 filters), randomly select 20 to 30 
filters from the lot and analyze the filter or filter strips for Pb. For 
smaller filter lots, a lesser number of filters can be analyzed. Glass, 
quartz and PTFE filters must not have levels of Pb above the criteria 
specified in section 7.7.4 and, therefore, blank correction should not 
be performed. If acceptance testing shows levels of Pb above the 
criteria in Section 7.7.4, corrective action must be taken to reduce the 
levels before proceeding.
    7.8 The Initial Calibration Verification (ICV), Lower Level 
Calibration Verification (LLCV), and Continuing Calibration Verification 
(CCV) solutions are prepared from a different Pb source than the 
calibration curve standards and at a concentration that is either at or 
below the midpoint on the calibration curve, but within the calibration 
range. Both are prepared in the same acid matrix as the calibration 
standards. Note that the same solution may be used for both the ICV and 
CCV. The ICV/CCV and LLCV solutions must be prepared fresh daily.

[[Page 78]]

    7.9 Tuning Solution. Prepare a tuning solution according to the 
instrument manufacturer's recommendations. This solution will be used to 
verify the mass calibration and resolution of the instrument.

                        8.0 Quality Control (QC)

    8.1 Standard QC practices shall be employed to assess the validity 
of the data generated, including: MDL, RB, duplicate samples, spiked 
samples, serial dilutions, ICV, CCV, LLCV, ICB, CCB, and SRMs/CRMs.
    8.2 MDLs must be calculated in accordance with 40 CFR part 136, 
Appendix B. RBs with low-level standard spikes are used to estimate the 
MDL. The low-level standard spike is added to at least 7 individual 
filter strips and then carried through the entire extraction procedure. 
This will result in at least 7 individual samples to be used for the 
MDL. The recommended range for spiking the strips is 1 to 5 times the 
estimated MDL.
    8.3 For each batch of samples, one RB and one reagent blank spike 
(RBS) that is spiked at the same level as the sample spike (see Section 
8.6) must be prepared and carried throughout the entire process. The 
results of the RB must be below 0.001 [micro]g/mL. The recovery for the 
RBS must be within 20 percent of the expected 
value. If the RB yields a result above 0.001 [micro]g/mL, the source of 
contamination must be identified and the extraction and analysis 
repeated. Reagents and labware must be suspected as sources of 
contamination. Screening of reagents and labware is addressed in Section 
4.1.
    8.4 Any samples that exceed the highest calibration standard must be 
diluted and rerun so that the concentration falls within the curve. The 
minimum dilution will be 1 to 5 with matrix matched acid solution.
    8.5 The internal standard response must be monitored during the 
analysis. If the internal standard response falls below 70 percent or 
rises above 120 percent of expected due to possible matrix effects, the 
sample must be diluted and reanalyzed. The minimum dilution will be 1 to 
5 with matrix matched acid solution. If the first dilution does not 
correct the problem, additional dilutions must be run until the internal 
standard falls within the specified range.
    8.6 For every batch of samples prepared, there must be one duplicate 
and one spike sample prepared. The spike added is to be at a level that 
falls within the calibration curve, normally the midpoint of the curve. 
The initial plus duplicate sample must yield a relative percent 
difference <=20 percent. The spike must be within 20 percent of the expected value.
    8.7 For each batch of samples, one extract must be diluted five-fold 
and analyzed. The corrected dilution result must be within 10 percent of the undiluted result. The sample chosen 
for the serial dilution shall have a concentration at or above 10X the 
lowest standard in the curve to ensure the diluted value falls within 
the curve. If the serial dilution fails, chemical or physical 
interference should be suspected.
    8.8 ICB, ICV, LLCV, CCB and CCV samples are to be run as shown in 
the following table.

------------------------------------------------------------------------
                                                        Performance
          Sample                  Frequency            specification
------------------------------------------------------------------------
ICB.......................  Prior to first sample  Less than 0.001
                                                    [micro]g/mL.
ICV.......................  Prior to first sample  Within 90 to 110
                                                    percent of the
                                                    expected value.
LLCV......................  Daily, before first    10 percent of the
                             last sample.           expected value.
CCB.......................  After every 10         Less than 0.001
                             extracted samples.     [micro]g/mL.
CCV.......................  After every 10         Within 90-110 percent
                             extracted samples.     of the expected
                                                    value.
------------------------------------------------------------------------

    If any of these QC samples fails to meet specifications, the source 
of the unacceptable performance must be determined, the problem 
corrected, and any samples not bracketed by passing QC samples must be 
reanalyzed.
    8.9 For each batch of samples, one certified reference material 
(CRM) must be combined with a blank filter strip and carried through the 
entire extraction procedure. The result must be within 10 percent of the expected value.
    8.10 For each run, a LLCV must be analyzed. The LLCV must be 
prepared at a concentration not more than three times the lowest 
calibration standard and at a concentration not used in the calibration 
curve. The LLCV is used to assess performance at the low end of the 
curve. If the LLCV fails (10 percent of the 
expected value) the run must be terminated, the problem corrected, the 
instrument recalibrated, and the analysis repeated.
    8.11 Pipettes used for volumetric transfer must have the calibration 
checked at least once every 6 months and pass 1 
percent accuracy and <=1 percent RSD (precision) based on five replicate 
readings. The pipettes must be checked weekly for accuracy with a single 
replicate. Any pipette that does not meet 1 
percent accuracy on the weekly check must be removed from service, 
repaired, and pass a full calibration check before use.
    8.12 Samples with physical deformities are not quantitatively 
analyzable. The analyst should visually check filters prior to 
proceeding with preparation for holes, tears, or non-uniform deposit 
which would prevent

[[Page 79]]

representative sampling. Document any deformities and qualify the data 
with flags appropriately. Care must be taken to protect filters from 
contamination. Filters must be kept covered prior to sample preparation.
    9.0 ICP MS Calibration
    Follow the instrument manufacturer's instructions for the routine 
maintenance, cleaning, and ignition procedures for the specific ICP-MS 
instrument being used.
    9.1 Ignite the plasma and wait for at least one half hour for the 
instrument to warm up before beginning any pre-analysis steps.
    9.2 For the Thermo X-Series with Xt cones, aspirate a 10 ng/mL 
tuning solution containing In, Bi, and Ce (Cerium). Monitor the 
intensities of In, Bi, Ce, and CeO (Cerium oxide) and adjust the 
instrument settings to achieve the highest In and Bi counts while 
minimizing the CeO/Ce oxide ratio. For other instruments, follow the 
manufacturer's recommended practice. Tune to meet the instrument 
manufacturer's specifications. After tuning, place the sample aspiration 
probe into a 2 percent HNO3 rinse solution for at least 5 
minutes to flush the system.
    9.3 Aspirate a 5 ng/mL solution containing Co, In, and Bi to perform 
a daily instrument stability check. Run 10 replicates of the solution. 
The percent RSD for the replicates must be less than 3 percent at all 
masses. If the percent RSD is greater than 3 percent, the sample 
introduction system, pump tubing, and tune should be examined, and the 
analysis repeated. Place the sample aspiration probe into a 2 percent 
HNO3 rinse solution for at least 5 minutes to flush the 
system.
    9.4 Load the calibration standards in the autosampler and analyze 
using the same method parameters that will be used to analyze samples. 
The curve must include one blank and at least 5 Pb-containing 
calibration standards. The correlation coefficient must be at least 
0.998 for the curve to be accepted. The lowest standard must recover 
15 percent of the expected value and the remaining 
standards must recover 10 percent of the expected 
value to be accepted.
    9.5 Immediately after the calibration curve is completed, analyze an 
ICV and an ICB. The ICV must be prepared from a different source of Pb 
than the calibration standards. The ICV must recover 90-110 percent of 
the expected value for the run to continue. The ICB must be less than 
0.001 [micro]g/mL. If either the ICV or the ICB fails, the run must be 
terminated, the problem identified and corrected, and the analysis re-
started.
    9.6 A LLCV, CCV and a CCB must be run after the ICV and ICB. A CCV 
and CCB must be run at a frequency of not less than every 10 extracted 
samples. A typical analytical run sequence would be: Calibration blank, 
Calibration standards, ICV, ICB, LLCV, CCV, CCB, Extracts 1-10, CCV, 
CCB, Extracts 11-20, CCV, CCB, Extracts 21-30, CCV, CCB, LLCV, CCV, CCB. 
Extracts are any field sample or QC samples that have been carried 
through the extraction process. The CCV solution is prepared from a 
different source than the calibration standards and may be the same as 
the ICV solution. The LLCV must be within 10 
percent of expected value. The CCV value must be within 10 percent of expected for the run to continue. The CCB 
must be less than 0.001 [micro]g/mL. If either the CCV, LLCV, or CCB 
fails, the run must be terminated, the problem identified and corrected, 
and the analysis re-started from the last passing CCV/LLCV/CCB set.
    9.7 A LLCV, CCV, and CCB set must be run at the end of the analysis. 
The LLCV must be within 30 percent of expected 
value. If either the CCV, LLCV, or CCB fails, the run must be 
terminated, the problem identified and corrected, and the analysis re-
started from the last passing CCV/LLCV/CCB set.

             10.0 Heated Ultrasonic Filter Strip Extraction

    All plasticware (e.g., Nalgene) and glassware used in the extraction 
procedures is soaked in 1 percent HNO3 (v/v) for at least 24 
hours and rinsed with reagent water prior to use. All mechanical 
pipettes used must be calibrated to 1 percent 
accuracy and <=1 percent RSD at a minimum of once every 6 months.
    10.1 Sample Preparation--Heated Ultrasonic Bath
    10.1.1 Extraction solution (1.03M HNO3 + 2.23M HCl). 
Prepare by adding 500 mL of deionized water to a 1000 mL flask, adding 
64.4 mL of concentrated HNO3 and 182 mL of concentrated HCl, 
shaking to mix, allowing solution to cool, diluting to volume with 
reagent water, and inverting several times to mix. Extraction solution 
must be prepared at least weekly.
    10.1.2 Use a ceramic knife and non-metal ruler, or other cutting 
device that will not contaminate the filter with Pb. Cut a \3/4\ inch x 
8 inch strip from the glass fiber or quartz filter by cutting a strip 
from the edge of the filter where it has been folded along the 10 inch 
side at least 1 inch from the right or left side to avoid the un-sampled 
area covered by the filter holder. The filters must be carefully handled 
to avoid dislodging deposits.
    10.1.3 Using plastic tweezers, roll the filter strip up in a coil 
and place the rolled strip in the bottom of a labeled 50 mL extraction 
tube. In a fume hood, add 15.00 0.15 mL of the 
extraction solution (see Section 10.1.1) using a calibrated mechanical 
pipette. Ensure that the extraction solution completely covers the 
filter strip.
    10.1.4 Loosely cap the 50 mL extraction tube and place it upright in 
a plastic rack. When all samples have been prepared, place the racks in 
an uncovered heated ultrasonic water bath that has been preheated to 80 
5

[[Page 80]]

[deg]C and ensure that the water level in the ultrasonic is above the 
level of the extraction solution in the tubes but well below the level 
of the extraction tube caps to avoid contamination. Start the ultrasonic 
bath and allow the unit to run for 1 hour 5 
minutes at 80 5 [deg]C.
    10.1.5 Remove the rack(s) from the ultrasonic bath and allow the 
racks to cool.
    10.1.6 Add 25.00 0.25 mL of D.I. water with a 
calibrated mechanical pipette to bring the sample to a final volume of 
40.0 0.4 mL. Tightly cap the tubes, and vortex mix 
or shake vigorously. Place the extraction tubes in an appropriate holder 
and centrifuge for 20 minutes at 2500 revolutions per minute (RPM).
    CAUTION--Make sure that the centrifuge holder has a flat bottom to 
support the flat bottomed extraction tubes.
    10.1.7 Pour an aliquot of the solution into an autosampler vial for 
ICP-MS analysis to avoid the potential for contamination. Do not pipette 
an aliquot of solution into the autosampler vial.
    10.1.8 Decant the extract to a clean tube, cap tightly, and store 
the sample extract at ambient laboratory temperature. Extracts may be 
stored for up to 6 months from the date of extraction.
    10.2 47 mm PTFE Filter Extraction--Heated Ultrasonic Bath
    10.2.1 Extraction solution (1.03M HNO3 + 2.23M HCl). 
Prepare by adding 500 mL of D.I. water to a 1000mL flask, adding 64.4 mL 
of concentrated HNO3 and 182 mL of concentrated HCl, shaking 
to mix, allowing solution to cool, diluting to volume with reagent 
water, and inverting several times to mix. Extraction solution must be 
prepared at least weekly.
    10.2.2 Using plastic tweezers, bend the PTFE filter into a U-shape 
and insert the filter into a labeled 50 mL extraction tube with the 
particle loaded side facing the center of the tube. Gently push the 
filter to the bottom of the extraction tube. In a fume hood, add 25.00 
0.15 mL of the extraction solution (see Section 
10.2.1) using a calibrated mechanical pipette. Ensure that the 
extraction solution completely covers the filter.
    10.2.3 Loosely cap the 50 mL extraction tube and place it upright in 
a plastic rack. When all samples have been prepared, place the racks in 
an uncovered heated ultrasonic water bath that has been preheated to 80 
5 [deg]C and ensure that the water level in the 
ultrasonic is above the level of the extraction solution in the tubes, 
but well below the level of the extraction tube caps to avoid 
contamination. Start the ultrasonic bath and allow the unit to run for 1 
hour 5 minutes at 80 5 
[deg]C.
    10.2.4 Remove the rack(s) from the ultrasonic bath and allow the 
racks to cool.
    10.2.5 Add 25.00 0.25 mL of D.I. water with a 
calibrated mechanical pipette to bring the sample to a final volume of 
50.0 0.4 mL. Tightly cap the tubes, and vortex mix 
or shake vigorously. Allow samples to stand for one hour to allow 
complete diffusion of the extracted Pb. The sample is now ready for 
analysis.
    Note: Although PTFE filters have only been extracted using the 
ultrasonic extraction procedure in the development of this FRM, PTFE 
filters are inert and have very low Pb content. No issues are expected 
with the extraction of PTFE filters using the heated block digestion 
method. However, prior to using PTFE filters in the heated block 
extraction method, extraction method performance test using CRMs must be 
done to confirm performance (see Section 8.9).

                 11.0 Hot Block Filter Strip Extraction

    All plasticware (e.g., Nalgene) and glassware used in the extraction 
procedures is soaked in 1 percent HNO3 for at least 24 hours 
and rinsed with reagent water prior to use. All mechanical pipettes used 
must be calibrated to 1 percent accuracy and <=1 
percent RSD at a minimum of once every 6 months.
    11.1 Sample Preparation--Hot Block Digestion
    11.1.1 Extraction solution (1:19, v/v HNO3). Prepare by 
adding 500 mL of D.I. water to a 1000 mL flask, adding 50 mL of 
concentrated HNO3, shaking to mix, allowing solution to cool, 
diluting to volume with reagent water, and inverting several times to 
mix. The extraction solution must be prepared at least weekly.
    11.1.2 Use a ceramic knife and non-metal ruler, or other cutting 
device that will not contaminate the filter with Pb. Cut a 1-inch x 8-
inch strip from the glass fiber or quartz filter. Cut a strip from the 
edge of the filter where it has been folded along the 10-inch side at 
least 1 inch from the right or left side to avoid the un-sampled area 
covered by the filter holder. The filters must be carefully handled to 
avoid dislodging particle deposits.
    11.1.3 Using plastic tweezers, roll the filter strip up in a coil 
and place the rolled strip in the bottom of a labeled 50 mL extraction 
tube. In a fume hood, add 20.0 0.15 mL of the 
extraction solution (see Section 11.1.1) using a calibrated mechanical 
pipette. Ensure that the extraction solution completely covers the 
filter strip.
    11.1.4 Place the extraction tube in the heated block digester and 
cover with a disposable polyethylene ribbed watch glass. Heat at 95 
5 [deg]C for 1 hour and ensure that the sample 
does not evaporate to dryness. For proper heating, adjust the 
temperature control of the hot block such that an uncovered vessel 
containing 50 mL of water placed in the center of the hot block can be 
maintained at a temperature approximately, but

[[Page 81]]

no higher than 85C. Once the vessel is covered with a ribbed watch 
glass, the temperature of the water will increase to approximately 95 
[deg]C.
    11.1.5 Remove the rack(s) from the heated block digester and allow 
the samples to cool.
    11.1.6 Bring the samples to a final volume of 50 mL with D.I. water. 
Tightly cap the tubes, and vortex mix or shake vigorously for at least 5 
seconds. Set aside (with the filter strip in the tube) for at least 30 
minutes to allow the HNO3 trapped in the filter to diffuse 
into the extraction solution.
    11.1.7 Shake thoroughly (with the filter strip in the digestion 
tube) and let settle for at least one hour. The sample is now ready for 
analysis.

                       12.0 Measurement Procedure

    12.1 Follow the instrument manufacturer's startup procedures for the 
ICP-MS.
    12.2 Set instrument parameters to the appropriate operating 
conditions as presented in the instrument manufacturer's operating 
manual and allow the instrument to warm up for at least 30 minutes.
    12.3 Calibrate the instrument per Section 9.0 of this method.
    12.4 Verify the instrument is suitable for analysis as defined in 
Sections 9.2 and 9.3.
    12.5 As directed in Section 8.0 of this method, analyze an ICV and 
ICB immediately after the calibration curve followed by a LLCV, then CCV 
and CCB. The acceptance requirements for these parameters are presented 
in Section 8.8.
    12.6 Analyze a CCV and a CCB after every 10 extracted samples.
    12.7 Analyze a LLCV, CCV and CCB at the end of the analysis.
    12.8 A typical sample run will include field samples, field sample 
duplicates, spiked field sample extracts, serially diluted samples, the 
set of QC samples listed in Section 8.8 above, and one or more CRMs or 
SRMs.
    12.9 Any samples that exceed the highest standard in the calibration 
curve must be diluted and reanalyzed so that the diluted concentration 
falls within the calibration curve.
    13.0 Results
    13.1 The filter results must be initially reported in [micro]g/mL as 
analyzed. Any additional dilutions must be accounted for. The internal 
standard recoveries must be included in the result calculation; this is 
done by the ICP-MS software for most commercially-available instruments. 
Final results should be reported in [micro]g Pb/m\3\ to three 
significant figures as follows:

C = (([micro]g Pb/mL * Vf * A)* D))/Vs

Where:

C = Concentration, [micro]g Pb/m\3\
[micro]g Pb/mL = Lead concentration in solution
Vf = Total extraction solution volume
A = Area correction; \3/4\ x 8 strip = 5.25 in\2\ 
          analyzed, A = 12.0 or 1 x 8 strip = 7 
          in\2\ analyzed, A = 9.0
D = dilution factor (if required)
Vs = Actual volume of air sampled

    The calculation assumes the use of a standard 8-inch x 10-inch TSP 
filter which has a sampled area of 9-inch x 7-inch (63.0 in\2\) due to 
the \1/2\-inch filter holder border around the outer edge. The \3/4\-
inch x 8-inch strip has a sampled area of \3/4\-inch x 7-inch (5.25 
in\2\). The 1-inch x 8-inch strip has a sampled area of 1-inch x 7-inch 
(7.0 in\2\). If filter lot blanks are provided for analysis, refer to 
Section 7.7.5 of this method for guidance on testing.

                         14.0 Method Performance

    Information in this section is an example of typical performance 
results achieved by this method. Actual performance must be demonstrated 
by each individual laboratory and instrument.
    14.1 Performance data have been collected to estimate MDLs for this 
method. MDLs were determined in accordance with 40 CFR 136, Appendix B. 
MDLs were estimated for glass fiber, quartz, and PTFE filters using 
seven reagent/filter blank solutions spiked with low level Pb at three 
times the estimated MDL of 0.001 [micro]g/mL. Tables 1, 3, and 5 shows 
the MDLs estimated using both the ultrasonic and hot block extraction 
methods for glass fiber and quartz filters and the ultrasonic method for 
PTFE filters. The MDLs are well below the EPA requirement of five 
percent of the current Pb NAAQS or 0.0075 [micro]g/m\3\. These MDLs are 
provided to demonstrate the adequacy of the method's performance for Pb 
in TSP. Each laboratory using this method should determine MDLs in their 
laboratory and verify them annually. It is recommended that laboratories 
also perform the optional iterative procedure in 40 CFR 136, Appendix B 
to verify the reasonableness of the estimated MDL and subsequent MDL 
determinations.
    14.2 Extraction method recovery tests with glass fiber and quartz 
filter strips, and PTFE filters spiked with NIST SRMs were performed 
using the ultrasonic/HNO3 and HCl filter extraction methods 
and measurement of the dissolved Pb with ICP-MS. Tables 2, 4, and 6 show 
recoveries obtained with these SRM. The recoveries for all SRMs were 
=90 percent at the 95 percent confidence level.

[[Page 82]]



Table 1--Method Detection Limits Determined by Analysis of Reagent/Glass
          Fiber Filter Blanks Spiked With Low-level Pb Solution
------------------------------------------------------------------------
                                                 Ultrasonic    Hotblock
                                                 extraction   extraction
                                                   method       method
                                               -------------------------
                                                 [micro]g/    [micro]g/
                                                    m\3\         m\3\
------------------------------------------------------------------------
n = 1.........................................    0.0000702     0.000533
n = 2.........................................    0.0000715     0.000482
n = 3.........................................    0.0000611     0.000509
n = 4.........................................    0.0000587     0.000427
n = 5.........................................    0.0000608     0.000449
n = 6.........................................    0.0000607     0.000539
n = 7.........................................    0.0000616     0.000481
Average.......................................    0.0000635     0.000489
Standard Deviation............................    0.0000051     0.000042
MDL**.........................................    0.0000161     0.000131
------------------------------------------------------------------------
* Assumes 2000 m\3\ of air sampled.
** MDL is 3.143 times the standard deviation of the results for seven
  sample replicates analyzed.


                   Table 2--Recoveries of Lead From NIST SRMs Spiked Onto Glass Fiber Filters
----------------------------------------------------------------------------------------------------------------
                                                                    Recovery, ICP-MS, (percent)
                                                 ---------------------------------------------------------------
                Extraction method                    NIST 1547                                       NIST 2582
                                                       plant      NIST 2709 soil  NIST 2583 dust       paint
----------------------------------------------------------------------------------------------------------------
Ultrasonic Bath.................................      100 3, HCl, and solutions containing these 
reagents and/or Pb must be placed in labeled bottles and delivered to a 
commercial firm that specializes in removal of hazardous waste.

                             17.0 References

FACDQ (2007). Report of the Federal Advisory Committee on Detection and 
          Quantitation Approaches and Uses in Clean Water Act Programs, 
          submitted to the U.S. EPA December 2007. Available: http://
          water.epa.gov/scitech/methods/cwa/det/upload/final-report-
          200712.pdf.
Rice J (2013). Results from the Development of a New Federal Reference 
          Method (FRM) for Lead in Total Suspended Particulate (TSP) 
          Matter. Docket  EPA-HQ-OAR-2012-0210.
U.S. EPA (2007). Method 6020A--Inductively Coupled Plasma Mass 
          Spectrometry. U.S. Environmental Protection Agency. Revision 
          1, February 2007. Available: http://www.epa.gov/osw/hazard/
          testmethods/sw846/pdfs/6020a.pdf.
U.S. EPA (2011). A Laboratory Study of Procedures Evaluated by the 
          Federal Advisory Committee on Detection and Quantitation 
          Approaches and Uses in Clean Water Act Programs. December 
          2011. Available: http://water.epa.gov/scitech/methods/cwa/det/
          upload/fac_report _2009.pdf.

[78 FR 40004, July 3, 2013]

[[Page 84]]



  Sec. Appendix H to Part 50--Interpretation of the 1-Hour Primary and 
       Secondary National Ambient Air Quality Standards for Ozone

                               1. General

    This appendix explains how to determine when the expected number of 
days per calendar year with maximum hourly average concentrations above 
0.12 ppm (235 [micro]g/m\3\) is equal to or less than 1. An expanded 
discussion of these procedures and associated examples are contained in 
the ``Guideline for Interpretation of Ozone Air Quality Standards.'' For 
purposes of clarity in the following discussion, it is convenient to use 
the term ``exceedance'' to describe a daily maximum hourly average ozone 
measurement that is greater than the level of the standard. Therefore, 
the phrase ``expected number of days with maximum hourly average ozone 
concentrations above the level of the standard'' may be simply stated as 
the ``expected number of exceedances.''
    The basic principle in making this determination is relatively 
straightforward. Most of the complications that arise in determining the 
expected number of annual exceedances relate to accounting for 
incomplete sampling. In general, the average number of exceedances per 
calendar year must be less than or equal to 1. In its simplest form, the 
number of exceedances at a monitoring site would be recorded for each 
calendar year and then averaged over the past 3 calendar years to 
determine if this average is less than or equal to 1.

                2. Interpretation of Expected Exceedances

    The ozone standard states that the expected number of exceedances 
per year must be less than or equal to 1. The statistical term 
``expected number'' is basically an arithmetic average. The following 
example explains what it would mean for an area to be in compliance with 
this type of standard. Suppose a monitoring station records a valid 
daily maximum hourly average ozone value for every day of the year 
during the past 3 years. At the end of each year, the number of days 
with maximum hourly concentrations above 0.12 ppm is determined and this 
number is averaged with the results of previous years. As long as this 
average remains ``less than or equal to 1,'' the area is in compliance.

           3. Estimating the Number of Exceedances for a Year

    In general, a valid daily maximum hourly average value may not be 
available for each day of the year, and it will be necessary to account 
for these missing values when estimating the number of exceedances for a 
particular calendar year. The purpose of these computations is to 
determine if the expected number of exceedances per year is less than or 
equal to 1. Thus, if a site has two or more observed exceedances each 
year, the standard is not met and it is not necessary to use the 
procedures of this section to account for incomplete sampling.
    The term ``missing value'' is used here in the general sense to 
describe all days that do not have an associated ozone measurement. In 
some cases, a measurement might actually have been missed but in other 
cases no measurement may have been scheduled for that day. A daily 
maximum ozone value is defined to be the highest hourly ozone value 
recorded for the day. This daily maximum value is considered to be valid 
if 75 percent of the hours from 9:01 a.m. to 9:00 p.m. (LST) were 
measured or if the highest hour is greater than the level of the 
standard.
    In some areas, the seasonal pattern of ozone is so pronounced that 
entire months need not be sampled because it is extremely unlikely that 
the standard would be exceeded. Any such waiver of the ozone monitoring 
requirement would be handled under provisions of 40 CFR, part 58. Some 
allowance should also be made for days for which valid daily maximum 
hourly values were not obtained but which would quite likely have been 
below the standard. Such an allowance introduces a complication in that 
it becomes necessary to define under what conditions a missing value may 
be assumed to have been less than the level of the standard. The 
following criterion may be used for ozone:
    A missing daily maximum ozone value may be assumed to be less than 
the level of the standard if the valid daily maxima on both the 
preceding day and the following day do not exceed 75 percent of the 
level of the standard.
    Let z denote the number of missing daily maximum values that may be 
assumed to be less than the standard. Then the following formula shall 
be used to estimate the expected number of exceedances for the year:
[GRAPHIC] [TIFF OMITTED] TC08NO91.086

    (*Indicates multiplication.)

where:

e = the estimated number of exceedances for the year,
N = the number of required monitoring days in the year,
n = the number of valid daily maxima,
v = the number of daily values above the level of the standard, and
z = the number of days assumed to be less than the standard level.

    This estimated number of exceedances shall be rounded to one decimal 
place (fractional parts equal to 0.05 round up).

[[Page 85]]

    It should be noted that N will be the total number of days in the 
year unless the appropriate Regional Administrator has granted a waiver 
under the provisions of 40 CFR part 58.
    The above equation may be interpreted intuitively in the following 
manner. The estimated number of exceedances is equal to the observed 
number of exceedances (v) plus an increment that accounts for incomplete 
sampling. There were (N-n) missing values for the year but a certain 
number of these, namely z, were assumed to be less than the standard. 
Therefore, (N-n-z) missing values are considered to include possible 
exceedances. The fraction of measured values that are above the level of 
the standard is v/n. It is assumed that this same fraction applies to 
the (N-n-z) missing values and that (v/n)*(N-n-z) of these values would 
also have exceeded the level of the standard.

[44 FR 8220, Feb. 8, 1979, as amended at 62 FR 38895, July 18, 1997]



  Sec. Appendix I to Part 50--Interpretation of the 8-Hour Primary and 
       Secondary National Ambient Air Quality Standards for Ozone

    1. General.
    This appendix explains the data handling conventions and 
computations necessary for determining whether the national 8-hour 
primary and secondary ambient air quality standards for ozone specified 
in Sec. 50.10 are met at an ambient ozone air quality monitoring site. 
Ozone is measured in the ambient air by a reference method based on 
appendix D of this part. Data reporting, data handling, and computation 
procedures to be used in making comparisons between reported ozone 
concentrations and the level of the ozone standard are specified in the 
following sections. Whether to exclude, retain, or make adjustments to 
the data affected by stratospheric ozone intrusion or other natural 
events is subject to the approval of the appropriate Regional 
Administrator.
    2. Primary and Secondary Ambient Air Quality Standards for Ozone.
    2.1 Data Reporting and Handling Conventions.
    2.1.1 Computing 8-hour averages. Hourly average concentrations shall 
be reported in parts per million (ppm) to the third decimal place, with 
additional digits to the right being truncated. Running 8-hour averages 
shall be computed from the hourly ozone concentration data for each hour 
of the year and the result shall be stored in the first, or start, hour 
of the 8-hour period. An 8-hour average shall be considered valid if at 
least 75% of the hourly averages for the 8-hour period are available. In 
the event that only 6 (or 7) hourly averages are available, the 8-hour 
average shall be computed on the basis of the hours available using 6 
(or 7) as the divisor. (8-hour periods with three or more missing hours 
shall not be ignored if, after substituting one-half the minimum 
detectable limit for the missing hourly concentrations, the 8-hour 
average concentration is greater than the level of the standard.) The 
computed 8-hour average ozone concentrations shall be reported to three 
decimal places (the insignificant digits to the right of the third 
decimal place are truncated, consistent with the data handling 
procedures for the reported data.)
    2.1.2 Daily maximum 8-hour average concentrations. (a) There are 24 
possible running 8-hour average ozone concentrations for each calendar 
day during the ozone monitoring season. (Ozone monitoring seasons vary 
by geographic location as designated in part 58, appendix D to this 
chapter.) The daily maximum 8-hour concentration for a given calendar 
day is the highest of the 24 possible 8-hour average concentrations 
computed for that day. This process is repeated, yielding a daily 
maximum 8-hour average ozone concentration for each calendar day with 
ambient ozone monitoring data. Because the 8-hour averages are recorded 
in the start hour, the daily maximum 8-hour concentrations from two 
consecutive days may have some hourly concentrations in common. 
Generally, overlapping daily maximum 8-hour averages are not likely, 
except in those non-urban monitoring locations with less pronounced 
diurnal variation in hourly concentrations.
    (b) An ozone monitoring day shall be counted as a valid day if valid 
8-hour averages are available for at least 75% of possible hours in the 
day (i.e., at least 18 of the 24 averages). In the event that less than 
75% of the 8-hour averages are available, a day shall also be counted as 
a valid day if the daily maximum 8-hour average concentration for that 
day is greater than the level of the ambient standard.
    2.2 Primary and Secondary Standard-related Summary Statistic. The 
standard-related summary statistic is the annual fourth-highest daily 
maximum 8-hour ozone concentration, expressed in parts per million, 
averaged over three years. The 3-year average shall be computed using 
the three most recent, consecutive calendar years of monitoring data 
meeting the data completeness requirements described in this appendix. 
The computed 3-year average of the annual fourth-highest daily maximum 
8-hour average ozone concentrations shall be expressed to three decimal 
places (the remaining digits to the right are truncated.)
    2.3 Comparisons with the Primary and Secondary Ozone Standards. (a) 
The primary and secondary ozone ambient air quality standards are met at 
an ambient air quality monitoring site when the 3-year average of the 
annual fourth-highest daily maximum 8-hour

[[Page 86]]

average ozone concentration is less than or equal to 0.08 ppm. The 
number of significant figures in the level of the standard dictates the 
rounding convention for comparing the computed 3-year average annual 
fourth-highest daily maximum 8-hour average ozone concentration with the 
level of the standard. The third decimal place of the computed value is 
rounded, with values equal to or greater than 5 rounding up. Thus, a 
computed 3-year average ozone concentration of 0.085 ppm is the smallest 
value that is greater than 0.08 ppm.
    (b) This comparison shall be based on three consecutive, complete 
calendar years of air quality monitoring data. This requirement is met 
for the three year period at a monitoring site if daily maximum 8-hour 
average concentrations are available for at least 90%, on average, of 
the days during the designated ozone monitoring season, with a minimum 
data completeness in any one year of at least 75% of the designated 
sampling days. When computing whether the minimum data completeness 
requirements have been met, meteorological or ambient data may be 
sufficient to demonstrate that meteorological conditions on missing days 
were not conducive to concentrations above the level of the standard. 
Missing days assumed less than the level of the standard are counted for 
the purpose of meeting the data completeness requirement, subject to the 
approval of the appropriate Regional Administrator.
    (c) Years with concentrations greater than the level of the standard 
shall not be ignored on the ground that they have less than complete 
data. Thus, in computing the 3-year average fourth maximum 
concentration, calendar years with less than 75% data completeness shall 
be included in the computation if the average annual fourth maximum 8-
hour concentration is greater than the level of the standard.
    (d) Comparisons with the primary and secondary ozone standards are 
demonstrated by examples 1 and 2 in paragraphs (d)(1) and (d) (2) 
respectively as follows:
    (1) As shown in example 1, the primary and secondary standards are 
met at this monitoring site because the 3-year average of the annual 
fourth-highest daily maximum 8-hour average ozone concentrations (i.e., 
0.084 ppm) is less than or equal to 0.08 ppm. The data completeness 
requirement is also met because the average percent of days with valid 
ambient monitoring data is greater than 90%, and no single year has less 
than 75% data completeness.

             Example 1. Ambient monitoring site attaining the primary and secondary ozone standards
----------------------------------------------------------------------------------------------------------------
                                                 1st Highest  2nd Highest  3rd Highest  4th Highest  5th Highest
                                      Percent    Daily Max 8- Daily Max 8- Daily Max 8- Daily Max 8- Daily Max 8-
               Year                  Valid Days   hour Conc.   hour Conc.   hour Conc.   hour Conc.   hour Conc.
                                                    (ppm)        (ppm)        (ppm)        (ppm)        (ppm)
----------------------------------------------------------------------------------------------------------------
1993..............................         100%        0.092        0.091        0.090        0.088        0.085
----------------------------------------------------------------------------------------------------------------
1994..............................          96%        0.090        0.089        0.086        0.084        0.080
----------------------------------------------------------------------------------------------------------------
1995..............................          98%        0.087        0.085        0.083        0.080        0.075
================================================================================================================
    Average.......................          98%
----------------------------------------------------------------------------------------------------------------

    (2) As shown in example 2, the primary and secondary standards are 
not met at this monitoring site because the 3-year average of the 
fourth-highest daily maximum 8-hour average ozone concentrations (i.e., 
0.093 ppm) is greater than 0.08 ppm. Note that the ozone concentration 
data for 1994 is used in these computations, even though the data 
capture is less than 75%, because the average fourth-highest daily 
maximum 8-hour average concentration is greater than 0.08 ppm.

          Example 2. Ambient Monitoring Site Failing to Meet the Primary and Secondary Ozone Standards
----------------------------------------------------------------------------------------------------------------
                                                 1st Highest  2nd Highest  3rd Highest  4th Highest  5th Highest
                                      Percent    Daily Max 8- Daily Max 8- Daily Max 8- Daily Max 8- Daily Max 8-
               Year                  Valid Days   hour Conc.   hour Conc.   hour Conc.   hour Conc.   hour Conc.
                                                    (ppm)        (ppm)        (ppm)        (ppm)        (ppm)
----------------------------------------------------------------------------------------------------------------
1993..............................          96%        0.105        0.103        0.103        0.102        0.102
----------------------------------------------------------------------------------------------------------------
1994..............................          74%        0.090        0.085        0.082        0.080        0.078
----------------------------------------------------------------------------------------------------------------
1995..............................          98%        0.103        0.101        0.101        0.097        0.095
================================================================================================================
    Average.......................          89%
----------------------------------------------------------------------------------------------------------------


[[Page 87]]

    3. Design Values for Primary and Secondary Ambient Air Quality 
Standards for Ozone. The air quality design value at a monitoring site 
is defined as that concentration that when reduced to the level of the 
standard ensures that the site meets the standard. For a concentration-
based standard, the air quality design value is simply the standard-
related test statistic. Thus, for the primary and secondary ozone 
standards, the 3-year average annual fourth-highest daily maximum 8-hour 
average ozone concentration is also the air quality design value for the 
site.

[62 FR 38895, July 18, 1997]



 Sec. Appendix J to Part 50--Reference Method for the Determination of 
         Particulate Matter as PM10 in the Atmosphere

    1.0 Applicability.
    1.1 This method provides for the measurement of the mass 
concentration of particulate matter with an aerodynamic diameter less 
than or equal to a nominal 10 micrometers (PM1O) in ambient 
air over a 24-hour period for purposes of determining attainment and 
maintenance of the primary and secondary national ambient air quality 
standards for particulate matter specified in Sec. 50.6 of this 
chapter. The measurement process is nondestructive, and the 
PM10 sample can be subjected to subsequent physical or 
chemical analyses. Quality assurance procedures and guidance are 
provided in part 58, appendices A and B, of this chapter and in 
References 1 and 2.
    2.0 Principle.
    2.1 An air sampler draws ambient air at a constant flow rate into a 
specially shaped inlet where the suspended particulate matter is 
inertially separated into one or more size fractions within the 
PM10 size range. Each size fraction in the PM1O 
size range is then collected on a separate filter over the specified 
sampling period. The particle size discrimination characteristics 
(sampling effectiveness and 50 percent cutpoint) of the sampler inlet 
are prescribed as performance specifications in part 53 of this chapter.
    2.2 Each filter is weighed (after moisture equilibration) before and 
after use to determine the net weight (mass) gain due to collected 
PM10. The total volume of air sampled, corrected to EPA 
reference conditions (25 C, 101.3 kPa), is determined from the measured 
flow rate and the sampling time. The mass concentration of 
PM10 in the ambient air is computed as the total mass of 
collected particles in the PM10 size range divided by the 
volume of air sampled, and is expressed in micrograms per standard cubic 
meter ([micro]g/std m\3\). For PM10 samples collected at 
temperatures and pressures significantly different from EPA reference 
conditions, these corrected concentrations sometimes differ 
substantially from actual concentrations (in micrograms per actual cubic 
meter), particularly at high elevations. Although not required, the 
actual PM10 concentration can be calculated from the 
corrected concentration, using the average ambient temperature and 
barometric pressure during the sampling period.
    2.3 A method based on this principle will be considered a reference 
method only if (a) the associated sampler meets the requirements 
specified in this appendix and the requirements in part 53 of this 
chapter, and (b) the method has been designated as a reference method in 
accordance with part 53 of this chapter.
    3.0 Range.
    3.1 The lower limit of the mass concentration range is determined by 
the repeatability of filter tare weights, assuming the nominal air 
sample volume for the sampler. For samplers having an automatic filter-
changing mechanism, there may be no upper limit. For samplers that do 
not have an automatic filter-changing mechanism, the upper limit is 
determined by the filter mass loading beyond which the sampler no longer 
maintains the operating flow rate within specified limits due to 
increased pressure drop across the loaded filter. This upper limit 
cannot be specified precisely because it is a complex function of the 
ambient particle size distribution and type, humidity, filter type, and 
perhaps other factors. Nevertheless, all samplers should be capable of 
measuring 24-hour PM10 mass concentrations of at least 300 
[micro]g/std m\3\ while maintaining the operating flow rate within the 
specified limits.
    4.0 Precision.
    4.1 The precision of PM10 samplers must be 5 [micro]g/
m\3\ for PM10 concentrations below 80 [micro]g/m\3\ and 7 
percent for PM10 concentrations above 80 [micro]g/m\3\, as 
required by part 53 of this chapter, which prescribes a test procedure 
that determines the variation in the PM10 concentration 
measurements of identical samplers under typical sampling conditions. 
Continual assessment of precision via collocated samplers is required by 
part 58 of this chapter for PM10 samplers used in certain 
monitoring networks.
    5.0 Accuracy.
    5.1 Because the size of the particles making up ambient particulate 
matter varies over a wide range and the concentration of particles 
varies with particle size, it is difficult to define the absolute 
accuracy of PM10 samplers. Part 53 of this chapter provides a 
specification for the sampling effectiveness of PM10 
samplers. This specification requires that the expected mass 
concentration calculated for a candidate PM10 sampler, when 
sampling a specified particle size distribution, be within 10 percent of that calculated

[[Page 88]]

for an ideal sampler whose sampling effectiveness is explicitly 
specified. Also, the particle size for 50 percent sampling effectiveness 
is required to be 10 0.5 micrometers. Other 
specifications related to accuracy apply to flow measurement and 
calibration, filter media, analytical (weighing) procedures, and 
artifact. The flow rate accuracy of PM10 samplers used in 
certain monitoring networks is required by part 58 of this chapter to be 
assessed periodically via flow rate audits.
    6.0 Potential Sources of Error.
    6.1 Volatile Particles. Volatile particles collected on filters are 
often lost during shipment and/or storage of the filters prior to the 
post-sampling weighing. \3\ Although shipment or storage of loaded 
filters is sometimes unavoidable, filters should be reweighed as soon as 
practical to minimize these losses.
    6.2 Artifacts. Positive errors in PM10 concentration 
measurements may result from retention of gaseous species on filters. 
4 5 Such errors include the retention of sulfur dioxide and 
nitric acid. Retention of sulfur dioxide on filters, followed by 
oxidation to sulfate, is referred to as artifact sulfate formation, a 
phenomenon which increases with increasing filter alkalinity. \6\ Little 
or no artifact sulfate formation should occur using filters that meet 
the alkalinity specification in section 7.2.4. Artifact nitrate 
formation, resulting primarily from retention of nitric acid, occurs to 
varying degrees on many filter types, including glass fiber, cellulose 
ester, and many quartz fiber filters. 5 7 8 9 10 Loss of true 
atmospheric particulate nitrate during or following sampling may also 
occur due to dissociation or chemical reaction. This phenomenon has been 
observed on Teflon [supreg] filters \8\ and inferred for quartz fiber 
filters. \11 12\ The magnitude of nitrate artifact errors in 
PM10 mass concentration measurements will vary with location 
and ambient temperature; however, for most sampling locations, these 
errors are expected to be small.
    6.3 Humidity. The effects of ambient humidity on the sample are 
unavoidable. The filter equilibration procedure in section 9.0 is 
designed to minimize the effects of moisture on the filter medium.
    6.4 Filter Handling. Careful handling of filters between presampling 
and postsampling weighings is necessary to avoid errors due to damaged 
filters or loss of collected particles from the filters. Use of a filter 
cartridge or cassette may reduce the magnitude of these errors. Filters 
must also meet the integrity specification in section 7.2.3.
    6.5 Flow Rate Variation. Variations in the sampler's operating flow 
rate may alter the particle size discrimination characteristics of the 
sampler inlet. The magnitude of this error will depend on the 
sensitivity of the inlet to variations in flow rate and on the particle 
distribution in the atmosphere during the sampling period. The use of a 
flow control device (section 7.1.3) is required to minimize this error.
    6.6 Air Volume Determination. Errors in the air volume determination 
may result from errors in the flow rate and/or sampling time 
measurements. The flow control device serves to minimize errors in the 
flow rate determination, and an elapsed time meter (section 7.1.5) is 
required to minimize the error in the sampling time measurement.
    7.0 Apparatus.
    7.1 PM10 Sampler.
    7.1.1 The sampler shall be designed to:
    a. Draw the air sample into the sampler inlet and through the 
particle collection filter at a uniform face velocity.
    b. Hold and seal the filter in a horizontal position so that sample 
air is drawn downward through the filter.
    c. Allow the filter to be installed and removed conveniently.
    d. Protect the filter and sampler from precipitation and prevent 
insects and other debris from being sampled.
    e. Minimize air leaks that would cause error in the measurement of 
the air volume passing through the filter.
    f. Discharge exhaust air at a sufficient distance from the sampler 
inlet to minimize the sampling of exhaust air.
    g. Minimize the collection of dust from the supporting surface.
    7.1.2 The sampler shall have a sample air inlet system that, when 
operated within a specified flow rate range, provides particle size 
discrimination characteristics meeting all of the applicable performance 
specifications prescribed in part 53 of this chapter. The sampler inlet 
shall show no significant wind direction dependence. The latter 
requirement can generally be satisfied by an inlet shape that is 
circularly symmetrical about a vertical axis.
    7.1.3 The sampler shall have a flow control device capable of 
maintaining the sampler's operating flow rate within the flow rate 
limits specified for the sampler inlet over normal variations in line 
voltage and filter pressure drop.
    7.1.4 The sampler shall provide a means to measure the total flow 
rate during the sampling period. A continuous flow recorder is 
recommended but not required. The flow measurement device shall be 
accurate to 2 percent.
    7.1.5 A timing/control device capable of starting and stopping the 
sampler shall be used to obtain a sample collection period of 24 1 hr (1,440 60 min). An elapsed 
time meter, accurate to within 15 minutes, shall 
be used to measure sampling time. This meter is optional for samplers 
with continuous flow recorders if the sampling time

[[Page 89]]

measurement obtained by means of the recorder meets the 15 minute accuracy specification.
    7.1.6 The sampler shall have an associated operation or instruction 
manual as required by part 53 of this chapter which includes detailed 
instructions on the calibration, operation, and maintenance of the 
sampler.
    7.2 Filters.
    7.2.1 Filter Medium. No commercially available filter medium is 
ideal in all respects for all samplers. The user's goals in sampling 
determine the relative importance of various filter characteristics 
(e.g., cost, ease of handling, physical and chemical characteristics, 
etc.) and, consequently, determine the choice among acceptable filters. 
Furthermore, certain types of filters may not be suitable for use with 
some samplers, particularly under heavy loading conditions (high mass 
concentrations), because of high or rapid increase in the filter flow 
resistance that would exceed the capability of the sampler's flow 
control device. However, samplers equipped with automatic filter-
changing mechanisms may allow use of these types of filters. The 
specifications given below are minimum requirements to ensure 
acceptability of the filter medium for measurement of PM10 
mass concentrations. Other filter evaluation criteria should be 
considered to meet individual sampling and analysis objectives.
    7.2.2 Collection Efficiency. =99 percent, as measured by 
the DOP test (ASTM-2986) with 0.3 [micro]m particles at the sampler's 
operating face velocity.
    7.2.3 Integrity. 5 [micro]g/m\3\ (assuming 
sampler's nominal 24-hour air sample volume). Integrity is measured as 
the PM10 concentration equivalent corresponding to the 
average difference between the initial and the final weights of a random 
sample of test filters that are weighed and handled under actual or 
simulated sampling conditions, but have no air sample passed through 
them (i.e., filter blanks). As a minimum, the test procedure must 
include initial equilibration and weighing, installation on an 
inoperative sampler, removal from the sampler, and final equilibration 
and weighing.
    7.2.4 Alkalinity. <25 microequivalents/gram of filter, as measured 
by the procedure given in Reference 13 following at least two months 
storage in a clean environment (free from contamination by acidic gases) 
at room temperature and humidity.
    7.3 Flow Rate Transfer Standard. The flow rate transfer standard 
must be suitable for the sampler's operating flow rate and must be 
calibrated against a primary flow or volume standard that is traceable 
to the National Bureau of Standards (NBS). The flow rate transfer 
standard must be capable of measuring the sampler's operating flow rate 
with an accuracy of 2 percent.
    7.4 Filter Conditioning Environment.
    7.4.1 Temperature range: 15 to 30 C.
    7.4.2 Temperature control: 3 C.
    7.4.3 Humidity range: 20% to 45% RH.
    7.4.4 Humidity control: 5% RH.
    7.5 Analytical Balance. The analytical balance must be suitable for 
weighing the type and size of filters required by the sampler. The range 
and sensitivity required will depend on the filter tare weights and mass 
loadings. Typically, an analytical balance with a sensitivity of 0.1 mg 
is required for high volume samplers (flow rates 0.5 m\3\/
min). Lower volume samplers (flow rates <0.5 m\3\/min) will require a 
more sensitive balance.
    8.0 Calibration.
    8.1 General Requirements.
    8.1.1 Calibration of the sampler's flow measurement device is 
required to establish traceability of subsequent flow measurements to a 
primary standard. A flow rate transfer standard calibrated against a 
primary flow or volume standard shall be used to calibrate or verify the 
accuracy of the sampler's flow measurement device.
    8.1.2 Particle size discrimination by inertial separation requires 
that specific air velocities be maintained in the sampler's air inlet 
system. Therefore, the flow rate through the sampler's inlet must be 
maintained throughout the sampling period within the design flow rate 
range specified by the manufacturer. Design flow rates are specified as 
actual volumetric flow rates, measured at existing conditions of 
temperature and pressure (Qa). In contrast, mass 
concentrations of PM10 are computed using flow rates 
corrected to EPA reference conditions of temperature and pressure 
(Qstd).
    8.2 Flow Rate Calibration Procedure.
    8.2.1 PM10 samplers employ various types of flow control 
and flow measurement devices. The specific procedure used for flow rate 
calibration or verification will vary depending on the type of flow 
controller and flow indicator employed. Calibration in terms of actual 
volumetric flow rates (Qa) is generally recommended, but 
other measures of flow rate (e.g., Qstd) may be used provided 
the requirements of section 8.1 are met. The general procedure given 
here is based on actual volumetric flow units (Qa) and serves 
to illustrate the steps involved in the calibration of a PM10 
sampler. Consult the sampler manufacturer's instruction manual and 
Reference 2 for specific guidance on calibration. Reference 14 provides 
additional information on the use of the commonly used measures of flow 
rate and their interrelationships.
    8.2.2 Calibrate the flow rate transfer standard against a primary 
flow or volume standard traceable to NBS. Establish a calibration 
relationship (e.g., an equation or family of curves) such that 
traceability to the primary standard is accurate to within 2 percent 
over the expected range of ambient conditions (i.e., temperatures and 
pressures) under

[[Page 90]]

which the transfer standard will be used. Recalibrate the transfer 
standard periodically.
    8.2.3 Following the sampler manufacturer's instruction manual, 
remove the sampler inlet and connect the flow rate transfer standard to 
the sampler such that the transfer standard accurately measures the 
sampler's flow rate. Make sure there are no leaks between the transfer 
standard and the sampler.
    8.2.4 Choose a minimum of three flow rates (actual m\3\/min), spaced 
over the acceptable flow rate range specified for the inlet (see 7.1.2) 
that can be obtained by suitable adjustment of the sampler flow rate. In 
accordance with the sampler manufacturer's instruction manual, obtain or 
verify the calibration relationship between the flow rate (actual m\3\/
min) as indicated by the transfer standard and the sampler's flow 
indicator response. Record the ambient temperature and barometric 
pressure. Temperature and pressure corrections to subsequent flow 
indicator readings may be required for certain types of flow measurement 
devices. When such corrections are necessary, correction on an 
individual or daily basis is preferable. However, seasonal average 
temperature and average barometric pressure for the sampling site may be 
incorporated into the sampler calibration to avoid daily corrections. 
Consult the sampler manufacturer's instruction manual and Reference 2 
for additional guidance.
    8.2.5 Following calibration, verify that the sampler is operating at 
its design flow rate (actual m\3\/min) with a clean filter in place.
    8.2.6 Replace the sampler inlet.
    9.0 Procedure.
    9.1 The sampler shall be operated in accordance with the specific 
guidance provided in the sampler manufacturer's instruction manual and 
in Reference 2. The general procedure given here assumes that the 
sampler's flow rate calibration is based on flow rates at ambient 
conditions (Qa) and serves to illustrate the steps involved 
in the operation of a PM10 sampler.
    9.2 Inspect each filter for pinholes, particles, and other 
imperfections. Establish a filter information record and assign an 
identification number to each filter.
    9.3 Equilibrate each filter in the conditioning environment (see 
7.4) for at least 24 hours.
    9.4 Following equilibration, weigh each filter and record the 
presampling weight with the filter identification number.
    9.5 Install a preweighed filter in the sampler following the 
instructions provided in the sampler manufacturer's instruction manual.
    9.6 Turn on the sampler and allow it to establish run-temperature 
conditions. Record the flow indicator reading and, if needed, the 
ambient temperature and barometric pressure. Determine the sampler flow 
rate (actual m\3\/min) in accordance with the instructions provided in 
the sampler manufacturer's instruction manual. NOTE.--No onsite 
temperature or pressure measurements are necessary if the sampler's flow 
indicator does not require temperature or pressure corrections or if 
seasonal average temperature and average barometric pressure for the 
sampling site are incorporated into the sampler calibration (see step 
8.2.4). If individual or daily temperature and pressure corrections are 
required, ambient temperature and barometric pressure can be obtained by 
on-site measurements or from a nearby weather station. Barometric 
pressure readings obtained from airports must be station pressure, not 
corrected to sea level, and may need to be corrected for differences in 
elevation between the sampling site and the airport.
    9.7 If the flow rate is outside the acceptable range specified by 
the manufacturer, check for leaks, and if necessary, adjust the flow 
rate to the specified setpoint. Stop the sampler.
    9.8 Set the timer to start and stop the sampler at appropriate 
times. Set the elapsed time meter to zero or record the initial meter 
reading.
    9.9 Record the sample information (site location or identification 
number, sample date, filter identification number, and sampler model and 
serial number).
    9.10 Sample for 24 1 hours.
    9.11 Determine and record the average flow rate (Qa) in 
actual m\3\/min for the sampling period in accordance with the 
instructions provided in the sampler manufacturer's instruction manual. 
Record the elapsed time meter final reading and, if needed, the average 
ambient temperature and barometric pressure for the sampling period (see 
note following step 9.6).
    9.12 Carefully remove the filter from the sampler, following the 
sampler manufacturer's instruction manual. Touch only the outer edges of 
the filter.
    9.13 Place the filter in a protective holder or container (e.g., 
petri dish, glassine envelope, or manila folder).
    9.14 Record any factors such as meteorological conditions, 
construction activity, fires or dust storms, etc., that might be 
pertinent to the measurement on the filter information record.
    9.15 Transport the exposed sample filter to the filter conditioning 
environment as soon as possible for equilibration and subsequent 
weighing.
    9.16 Equilibrate the exposed filter in the conditioning environment 
for at least 24 hours under the same temperature and humidity conditions 
used for presampling filter equilibration (see 9.3).
    9.17 Immediately after equilibration, reweigh the filter and record 
the postsampling weight with the filter identification number.
    10.0 Sampler Maintenance.

[[Page 91]]

    10.1 The PM10 sampler shall be maintained in strict 
accordance with the maintenance procedures specified in the sampler 
manufacturer's instruction manual.
    11.0 Calculations.
    11.1 Calculate the average flow rate over the sampling period 
corrected to EPA reference conditions as Qstd. When the 
sampler's flow indicator is calibrated in actual volumetric units 
(Qa), Qstd is calculated as:

Qstd = Qa x (Pav/
          Tav)(Tstd/Pstd)

where

Qstd = average flow rate at EPA reference conditions, std 
          m\3\/min;
Qa = average flow rate at ambient conditions, m\3\/min;
Pav = average barometric pressure during the sampling period 
          or average barometric pressure for the sampling site, kPa (or 
          mm Hg);
Tav = average ambient temperature during the sampling period 
          or seasonal average ambient temperature for the sampling site, 
          K;
Tstd = standard temperature, defined as 298 K;
Pstd = standard pressure, defined as 101.3 kPa (or 760 mm 
          Hg).

    11.2 Calculate the total volume of air sampled as:

Vstd = Qstd x t

where

Vstd = total air sampled in standard volume units, std m\3\;
t = sampling time, min.

    11.3 Calculate the PM10 concentration as:

PM10 = (Wf-Wi) x 10\6\/Vstd

where

PM10 = mass concentration of PM10, [micro]g/std 
          m\3\;
Wf, Wi = final and initial weights of filter 
          collecting PM1O particles, g;
10\6\ = conversion of g to [micro]g.

    Note: If more than one size fraction in the PM10 size 
range is collected by the sampler, the sum of the net weight gain by 
each collection filter [[Sigma](Wf-Wi)] is used to 
calculate the PM10 mass concentration.
    12.0 References.
    1. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume I, Principles. EPA-600/9-76-005, March 1976. Available from CERI, 
ORD Publications, U.S. Environmental Protection Agency, 26 West St. 
Clair Street, Cincinnati, OH 45268.
    2. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume II, Ambient Air Specific Methods. EPA-600/4-77-027a, May 1977. 
Available from CERI, ORD Publications, U.S. Environmental Protection 
Agency, 26 West St. Clair Street, Cincinnati, OH 45268.
    3. Clement, R.E., and F.W. Karasek. Sample Composition Changes in 
Sampling and Analysis of Organic Compounds in Aerosols. Int. J. Environ. 
Analyt. Chem., 7:109, 1979.
    4. Lee, R.E., Jr., and J. Wagman. A Sampling Anomaly in the 
Determination of Atmospheric Sulfate Concentration. Amer. Ind. Hyg. 
Assoc. J., 27:266, 1966.
    5. Appel, B.R., S.M. Wall, Y. Tokiwa, and M. Haik. Interference 
Effects in Sampling Particulate Nitrate in Ambient Air. Atmos. Environ., 
13:319, 1979.
    6. Coutant, R.W. Effect of Environmental Variables on Collection of 
Atmospheric Sulfate. Environ. Sci. Technol., 11:873, 1977.
    7. Spicer, C.W., and P. Schumacher. Interference in Sampling 
Atmospheric Particulate Nitrate. Atmos. Environ., 11:873, 1977.
    8. Appel, B.R., Y. Tokiwa, and M. Haik. Sampling of Nitrates in 
Ambient Air. Atmos. Environ., 15:283, 1981.
    9. Spicer, C.W., and P.M. Schumacher. Particulate Nitrate: 
Laboratory and Field Studies of Major Sampling Interferences. Atmos. 
Environ., 13:543, 1979.
    10. Appel, B.R. Letter to Larry Purdue, U.S. EPA, Environmental 
Monitoring and Support Laboratory. March 18, 1982, Docket No. A-82-37, 
II-I-1.
    11. Pierson, W.R., W.W. Brachaczek, T.J. Korniski, T.J. Truex, and 
J.W. Butler. Artifact Formation of Sulfate, Nitrate, and Hydrogen Ion on 
Backup Filters: Allegheny Mountain Experiment. J. Air Pollut. Control 
Assoc., 30:30, 1980.
    12. Dunwoody, C.L. Rapid Nitrate Loss From PM10 Filters. 
J. Air Pollut. Control Assoc., 36:817, 1986.
    13. Harrell, R.M. Measuring the Alkalinity of Hi-Vol Air Filters. 
EMSL/RTP-SOP-QAD-534, October 1985. Available from the U.S. 
Environmental Protection Agency, EMSL/QAD, Research Triangle Park, NC 
27711.
    14. Smith, F., P.S. Wohlschlegel, R.S.C. Rogers, and D.J. Mulligan. 
Investigation of Flow Rate Calibration Procedures Associated With the 
High Volume Method for Determination of Suspended Particulates. EPA-600/
4-78-047, U.S. Environmental Protection Agency, Research Triangle Park, 
NC 27711, 1978.

[52 FR 24664, July 1, 1987; 52 FR 29467, Aug. 7, 1987]



 Sec. Appendix K to Part 50--Interpretation of the National Ambient Air 
                Quality Standards for Particulate Matter

                               1.0 General

    (a) This appendix explains the computations necessary for analyzing 
particulate matter data to determine attainment of the 24-hour standards 
specified in 40 CFR 50.6. For the primary and secondary standards, 
particulate matter is measured in the ambient air as PM10 
(particles with an aerodynamic diameter less than or equal to a

[[Page 92]]

nominal 10 micrometers) by a reference method based on appendix J of 
this part and designated in accordance with part 53 of this chapter, or 
by an equivalent method designated in accordance with part 53 of this 
chapter. The required frequency of measurements is specified in part 58 
of this chapter.
    (b) The terms used in this appendix are defined as follows:
    Average refers to the arithmetic mean of the estimated number of 
exceedances per year, as per Section 3.1.
    Daily value for PM10 refers to the 24-hour average 
concentration of PM10 calculated or measured from midnight to 
midnight (local time).
    Exceedance means a daily value that is above the level of the 24-
hour standard after rounding to the nearest 10 [micro]g/m\3\ (i.e., 
values ending in 5 or greater are to be rounded up).
    Expected annual value is the number approached when the annual 
values from an increasing number of years are averaged, in the absence 
of long-term trends in emissions or meteorological conditions.
    Year refers to a calendar year.
    (c) Although the discussion in this appendix focuses on monitored 
data, the same principles apply to modeling data, subject to EPA 
modeling guidelines.

                      2.0 Attainment Determinations

               2.1 24-Hour Primary and Secondary Standards

    (a) Under 40 CFR 50.6(a) the 24-hour primary and secondary standards 
are attained when the expected number of exceedances per year at each 
monitoring site is less than or equal to one. In the simplest case, the 
number of expected exceedances at a site is determined by recording the 
number of exceedances in each calendar year and then averaging them over 
the past 3 calendar years. Situations in which 3 years of data are not 
available and possible adjustments for unusual events or trends are 
discussed in sections 2.3 and 2.4 of this appendix. Further, when data 
for a year are incomplete, it is necessary to compute an estimated 
number of exceedances for that year by adjusting the observed number of 
exceedances. This procedure, performed by calendar quarter, is described 
in section 3.0 of this appendix. The expected number of exceedances is 
then estimated by averaging the individual annual estimates for the past 
3 years.
    (b) The comparison with the allowable expected exceedance rate of 
one per year is made in terms of a number rounded to the nearest tenth 
(fractional values equal to or greater than 0.05 are to be rounded up; 
e.g., an exceedance rate of 1.05 would be rounded to 1.1, which is the 
lowest rate for nonattainment).

                              2.2 Reserved

                          2.3 Data Requirements

    (a) 40 CFR 58.12 specifies the required minimum frequency of 
sampling for PM10. For the purposes of making comparisons 
with the particulate matter standards, all data produced by State and 
Local Air Monitoring Stations (SLAMS) and other sites submitted to EPA 
in accordance with the part 58 requirements must be used, and a minimum 
of 75 percent of the scheduled PM10 samples per quarter are 
required.
    (b) To demonstrate attainment of the 24-hour standards at a 
monitoring site, the monitor must provide sufficient data to perform the 
required calculations of sections 3.0 and 4.0 of this appendix. The 
amount of data required varies with the sampling frequency, data capture 
rate and the number of years of record. In all cases, 3 years of 
representative monitoring data that meet the 75 percent criterion of the 
previous paragraph should be utilized, if available, and would suffice. 
More than 3 years may be considered, if all additional representative 
years of data meeting the 75 percent criterion are utilized. Data not 
meeting these criteria may also suffice to show attainment; however, 
such exceptions will have to be approved by the appropriate Regional 
Administrator in accordance with EPA guidance.
    (c) There are less stringent data requirements for showing that a 
monitor has failed an attainment test and thus has recorded a violation 
of the particulate matter standards. Although it is generally necessary 
to meet the minimum 75 percent data capture requirement per quarter to 
use the computational equations described in section 3.0 of this 
appendix, this criterion does not apply when less data is sufficient to 
unambiguously establish nonattainment. The following examples illustrate 
how nonattainment can be demonstrated when a site fails to meet the 
completeness criteria. Nonattainment of the 24-hour primary standards 
can be established by the observed annual number of exceedances (e.g., 
four observed exceedances in a single year), or by the estimated number 
of exceedances derived from the observed number of exceedances and the 
required number of scheduled samples (e.g., two observed exceedances 
with every other day sampling). In both cases, expected annual values 
must exceed the levels allowed by the standards.

            2.4 Adjustment for Exceptional Events and Trends

    (a) An exceptional event is an uncontrollable event caused by 
natural sources of particulate matter or an event that is not expected 
to recur at a given location. Inclusion of such a value in the 
computation of

[[Page 93]]

exceedances or averages could result in inappropriate estimates of their 
respective expected annual values. To reduce the effect of unusual 
events, more than 3 years of representative data may be used. 
Alternatively, other techniques, such as the use of statistical models 
or the use of historical data could be considered so that the event may 
be discounted or weighted according to the likelihood that it will 
recur. The use of such techniques is subject to the approval of the 
appropriate Regional Administrator in accordance with EPA guidance.
    (b) In cases where long-term trends in emissions and air quality are 
evident, mathematical techniques should be applied to account for the 
trends to ensure that the expected annual values are not inappropriately 
biased by unrepresentative data. In the simplest case, if 3 years of 
data are available under stable emission conditions, this data should be 
used. In the event of a trend or shift in emission patterns, either the 
most recent representative year(s) could be used or statistical 
techniques or models could be used in conjunction with previous years of 
data to adjust for trends. The use of less than 3 years of data, and any 
adjustments are subject to the approval of the appropriate Regional 
Administrator in accordance with EPA guidance.

          3.0 Computational Equations for the 24-Hour Standards

                  3.1 Estimating Exceedances for a Year

    (a) If PM10 sampling is scheduled less frequently than 
every day, or if some scheduled samples are missed, a PM10 
value will not be available for each day of the year. To account for the 
possible effect of incomplete data, an adjustment must be made to the 
data collected at each monitoring location to estimate the number of 
exceedances in a calendar year. In this adjustment, the assumption is 
made that the fraction of missing values that would have exceeded the 
standard level is identical to the fraction of measured values above 
this level. This computation is to be made for all sites that are 
scheduled to monitor throughout the entire year and meet the minimum 
data requirements of section 2.3 of this appendix. Because of possible 
seasonal imbalance, this adjustment shall be applied on a quarterly 
basis. The estimate of the expected number of exceedances for the 
quarter is equal to the observed number of exceedances plus an increment 
associated with the missing data. The following equation must be used 
for these computations:
[GRAPHIC] [TIFF OMITTED] TR17OC06.000

Where:

eq = the estimated number of exceedances for calendar quarter 
          q;
vq = the observed number of exceedances for calendar quarter 
          q;
Nq = the number of days in calendar quarter q;
nq = the number of days in calendar quarter q with 
          PM10 data; and
q = the index for calendar quarter, q = 1, 2, 3 or 4.

    (b) The estimated number of exceedances for a calendar quarter must 
be rounded to the nearest hundredth (fractional values equal to or 
greater than 0.005 must be rounded up).
    (c) The estimated number of exceedances for the year, e, is the sum 
of the estimates for each calendar quarter.
[GRAPHIC] [TIFF OMITTED] TR17OC06.001

    (d) The estimated number of exceedances for a single year must be 
rounded to one decimal place (fractional values equal to or greater than 
0.05 are to be rounded up). The expected number of exceedances is then 
estimated by averaging the individual annual estimates for the most 
recent 3 or more representative years of data. The expected number of 
exceedances must be rounded to one decimal place (fractional values 
equal to or greater than 0.05 are to be rounded up).
    (e) The adjustment for incomplete data will not be necessary for 
monitoring or modeling data which constitutes a complete record, i.e., 
365 days per year.
    (f) To reduce the potential for overestimating the number of 
expected exceedances, the correction for missing data will not be 
required for a calendar quarter in which the first observed exceedance 
has occurred if:
    (1) There was only one exceedance in the calendar quarter;
    (2) Everyday sampling is subsequently initiated and maintained for 4 
calendar quarters in accordance with 40 CFR 58.12; and
    (3) Data capture of 75 percent is achieved during the required 
period of everyday sampling. In addition, if the first exceedance is 
observed in a calendar quarter in which the monitor is already sampling 
every day, no adjustment for missing data will be made to the first 
exceedance if a 75 percent data capture rate was achieved in the quarter 
in which it was observed.

[[Page 94]]

                                Example 1

    a. During a particular calendar quarter, 39 out of a possible 92 
samples were recorded, with one observed exceedance of the 24-hour 
standard. Using Equation 1, the estimated number of exceedances for the 
quarter is:

eq = 1 x 92/39 = 2.359 or 2.36.

    b. If the estimated exceedances for the other 3 calendar quarters in 
the year were 2.30, 0.0 and 0.0, then, using Equation 2, the estimated 
number of exceedances for the year is 2.36 + 2.30 + 0.0 + 0.0 which 
equals 4.66 or 4.7. If no exceedances were observed for the 2 previous 
years, then the expected number of exceedances is estimated by: (\1/3\) 
x (4.7 + 0 + 0) = 1.57 or 1.6. Since 1.6 exceeds the allowable number of 
expected exceedances, this monitoring site would fail the attainment 
test.

                                Example 2

    In this example, everyday sampling was initiated following the first 
observed exceedance as required by 40 CFR 58.12. Accordingly, the first 
observed exceedance would not be adjusted for incomplete sampling. 
During the next three quarters, 1.2 exceedances were estimated. In this 
case, the estimated exceedances for the year would be 1.0 + 1.2 + 0.0 + 
0.0 which equals 2.2. If, as before, no exceedances were observed for 
the two previous years, then the estimated exceedances for the 3-year 
period would then be (\1/3\) x (2.2 + 0.0 + 0.0) = 0.7, and the 
monitoring site would not fail the attainment test.

             3.2 Adjustments for Non-Scheduled Sampling Days

    (a) If a systematic sampling schedule is used and sampling is 
performed on days in addition to the days specified by the systematic 
sampling schedule, e.g., during episodes of high pollution, then an 
adjustment must be made in the equation for the estimation of 
exceedances. Such an adjustment is needed to eliminate the bias in the 
estimate of the quarterly and annual number of exceedances that would 
occur if the chance of an exceedance is different for scheduled than for 
non-scheduled days, as would be the case with episode sampling.
    (b) The required adjustment treats the systematic sampling schedule 
as a stratified sampling plan. If the period from one scheduled sample 
until the day preceding the next scheduled sample is defined as a 
sampling stratum, then there is one stratum for each scheduled sampling 
day. An average number of observed exceedances is computed for each of 
these sampling strata. With nonscheduled sampling days, the estimated 
number of exceedances is defined as:
[GRAPHIC] [TIFF OMITTED] TR17OC06.002

Where:

eq = the estimated number of exceedances for the quarter;
Nq = the number of days in the quarter;
mq = the number of strata with samples during the quarter;
vj = the number of observed exceedances in stratum j; and
kj = the number of actual samples in stratum j.

    (c) Note that if only one sample value is recorded in each stratum, 
then Equation 3 reduces to Equation 1.

                                Example 3

    A monitoring site samples according to a systematic sampling 
schedule of one sample every 6 days, for a total of 15 scheduled samples 
in a quarter out of a total of 92 possible samples. During one 6-day 
period, potential episode levels of PM10 were suspected, so 5 
additional samples were taken. One of the regular scheduled samples was 
missed, so a total of 19 samples in 14 sampling strata were measured. 
The one 6-day sampling stratum with 6 samples recorded 2 exceedances. 
The remainder of the quarter with one sample per stratum recorded zero 
exceedances. Using Equation 3, the estimated number of exceedances for 
the quarter is:

    Eq = (92/14) x (2/6 + 0 + . . . + 0) = 2.19.

[71 FR 61224, Oct. 17, 2006]



 Sec. Appendix L to Part 50--Reference Method for the Determination of 
      Fine Particulate Matter as PM2.5 in the Atmosphere

    1.0 Applicability.
    1.1 This method provides for the measurement of the mass 
concentration of fine particulate matter having an aerodynamic diameter 
less than or equal to a nominal 2.5 micrometers (PM2.5) in 
ambient air over a 24-hour period for purposes of determining whether 
the primary and secondary national ambient air quality standards for 
fine particulate matter specified in Sec. 50.7 and Sec. 50.13 of this 
part are met. The measurement process is considered to be 
nondestructive, and the PM2.5 sample obtained can be 
subjected to subsequent physical or chemical analyses. Quality 
assessment procedures are provided in part 58, appendix A of this 
chapter, and quality assurance guidance are provided in references 1, 2, 
and 3 in section 13.0 of this appendix.

[[Page 95]]

    1.2 This method will be considered a reference method for purposes 
of part 58 of this chapter only if:
    (a) The associated sampler meets the requirements specified in this 
appendix and the applicable requirements in part 53 of this chapter, and
    (b) The method and associated sampler have been designated as a 
reference method in accordance with part 53 of this chapter.
    1.3 PM2.5 samplers that meet nearly all specifications 
set forth in this method but have minor deviations and/or modifications 
of the reference method sampler will be designated as ``Class I'' 
equivalent methods for PM2.5 in accordance with part 53 of 
this chapter.
    2.0 Principle.
    2.1 An electrically powered air sampler draws ambient air at a 
constant volumetric flow rate into a specially shaped inlet and through 
an inertial particle size separator (impactor) where the suspended 
particulate matter in the PM2.5 size range is separated for 
collection on a polytetrafluoroethylene (PTFE) filter over the specified 
sampling period. The air sampler and other aspects of this reference 
method are specified either explicitly in this appendix or generally 
with reference to other applicable regulations or quality assurance 
guidance.
    2.2 Each filter is weighed (after moisture and temperature 
conditioning) before and after sample collection to determine the net 
gain due to collected PM2.5. The total volume of air sampled 
is determined by the sampler from the measured flow rate at actual 
ambient temperature and pressure and the sampling time. The mass 
concentration of PM2.5 in the ambient air is computed as the 
total mass of collected particles in the PM2.5 size range 
divided by the actual volume of air sampled, and is expressed in 
micrograms per cubic meter of air ([micro]g/m\3\).
    3.0 PM2.5 Measurement Range.
    3.1 Lower concentration limit. The lower detection limit of the mass 
concentration measurement range is estimated to be approximately 2 
[micro]g/m\3\, based on noted mass changes in field blanks in 
conjunction with the 24 m\3\ nominal total air sample volume specified 
for the 24-hour sample.
    3.2 Upper concentration limit. The upper limit of the mass 
concentration range is determined by the filter mass loading beyond 
which the sampler can no longer maintain the operating flow rate within 
specified limits due to increased pressure drop across the loaded 
filter. This upper limit cannot be specified precisely because it is a 
complex function of the ambient particle size distribution and type, 
humidity, the individual filter used, the capacity of the sampler flow 
rate control system, and perhaps other factors. Nevertheless, all 
samplers are estimated to be capable of measuring 24-hour 
PM2.5 mass concentrations of at least 200 [micro]g/m\3\ while 
maintaining the operating flow rate within the specified limits.
    3.3 Sample period. The required sample period for PM2.5 
concentration measurements by this method shall be 1,380 to 1500 minutes 
(23 to 25 hours). However, when a sample period is less than 1,380 
minutes, the measured concentration (as determined by the collected 
PM2.5 mass divided by the actual sampled air volume), 
multiplied by the actual number of minutes in the sample period and 
divided by 1,440, may be used as if it were a valid concentration 
measurement for the specific purpose of determining a violation of the 
NAAQS. This value assumes that the PM2.5 concentration is 
zero for the remaining portion of the sample period and therefore 
represents the minimum concentration that could have been measured for 
the full 24-hour sample period. Accordingly, if the value thus 
calculated is high enough to be an exceedance, such an exceedance would 
be a valid exceedance for the sample period. When reported to AIRS, this 
data value should receive a special code to identify it as not to be 
commingled with normal concentration measurements or used for other 
purposes.
    4.0 Accuracy.
    4.1 Because the size and volatility of the particles making up 
ambient particulate matter vary over a wide range and the mass 
concentration of particles varies with particle size, it is difficult to 
define the accuracy of PM2.5 measurements in an absolute 
sense. The accuracy of PM2.5 measurements is therefore 
defined in a relative sense, referenced to measurements provided by this 
reference method. Accordingly, accuracy shall be defined as the degree 
of agreement between a subject field PM2.5 sampler and a 
collocated PM2.5 reference method audit sampler operating 
simultaneously at the monitoring site location of the subject sampler 
and includes both random (precision) and systematic (bias) errors. The 
requirements for this field sampler audit procedure are set forth in 
part 58, appendix A of this chapter.
    4.2 Measurement system bias. Results of collocated measurements 
where the duplicate sampler is a reference method sampler are used to 
assess a portion of the measurement system bias according to the 
schedule and procedure specified in part 58, appendix A of this chapter.
    4.3 Audits with reference method samplers to determine system 
accuracy and bias. According to the schedule and procedure specified in 
part 58, appendix A of this chapter, a reference method sampler is 
required to be located at each of selected PM2.5 SLAMS sites 
as a duplicate sampler. The results from the primary sampler and the 
duplicate reference method sampler are used to calculate accuracy of the 
primary sampler on a quarterly

[[Page 96]]

basis, bias of the primary sampler on an annual basis, and bias of a 
single reporting organization on an annual basis. Reference 2 in section 
13.0 of this appendix provides additional information and guidance on 
these reference method audits.
    4.4 Flow rate accuracy and bias. Part 58, appendix A of this chapter 
requires that the flow rate accuracy and bias of individual 
PM2.5 samplers used in SLAMS monitoring networks be assessed 
periodically via audits of each sampler's operational flow rate. In 
addition, part 58, appendix A of this chapter requires that flow rate 
bias for each reference and equivalent method operated by each reporting 
organization be assessed quarterly and annually. Reference 2 in section 
13.0 of this appendix provides additional information and guidance on 
flow rate accuracy audits and calculations for accuracy and bias.
    5.0 Precision. A data quality objective of 10 percent coefficient of 
variation or better has been established for the operational precision 
of PM2.5 monitoring data.
    5.1 Tests to establish initial operational precision for each 
reference method sampler are specified as a part of the requirements for 
designation as a reference method under Sec. 53.58 of this chapter.
    5.2 Measurement System Precision. Collocated sampler results, where 
the duplicate sampler is not a reference method sampler but is a sampler 
of the same designated method as the primary sampler, are used to assess 
measurement system precision according to the schedule and procedure 
specified in part 58, appendix A of this chapter. Part 58, appendix A of 
this chapter requires that these collocated sampler measurements be used 
to calculate quarterly and annual precision estimates for each primary 
sampler and for each designated method employed by each reporting 
organization. Reference 2 in section 13.0 of this appendix provides 
additional information and guidance on this requirement.
    6.0 Filter for PM2.5 Sample Collection. Any filter 
manufacturer or vendor who sells or offers to sell filters specifically 
identified for use with this PM2.5 reference method shall 
certify that the required number of filters from each lot of filters 
offered for sale as such have been tested as specified in this section 
6.0 and meet all of the following design and performance specifications.
    6.1 Size. Circular, 46.2 mm diameter 0.25 mm.
    6.2 Medium. Polytetrafluoroethylene (PTFE Teflon), with integral 
support ring.
    6.3 Support ring. Polymethylpentene (PMP) or equivalent inert 
material, 0.38 0.04 mm thick, outer diameter 46.2 
mm 0.25 mm, and width of 3.68 mm (0.00, -0.51 mm).
    6.4 Pore size. 2 [micro]m as measured by ASTM F 316-94.
    6.5 Filter thickness. 30 to 50 [micro]m.
    6.6 Maximum pressure drop (clean filter). 30 cm H2O 
column @ 16.67 L/min clean air flow.
    6.7 Maximum moisture pickup. Not more than 10 [micro]g weight 
increase after 24-hour exposure to air of 40 percent relative humidity, 
relative to weight after 24-hour exposure to air of 35 percent relative 
humidity.
    6.8 Collection efficiency. Greater than 99.7 percent, as measured by 
the DOP test (ASTM D 2986-91) with 0.3 [micro]m particles at the 
sampler's operating face velocity.
    6.9 Filter weight stability. Filter weight loss shall be less than 
20 [micro]g, as measured in each of the following two tests specified in 
sections 6.9.1 and 6.9.2 of this appendix. The following conditions 
apply to both of these tests: Filter weight loss shall be the average 
difference between the initial and the final filter weights of a random 
sample of test filters selected from each lot prior to sale. The number 
of filters tested shall be not less than 0.1 percent of the filters of 
each manufacturing lot, or 10 filters, whichever is greater. The filters 
shall be weighed under laboratory conditions and shall have had no air 
sample passed through them, i.e., filter blanks. Each test procedure 
must include initial conditioning and weighing, the test, and final 
conditioning and weighing. Conditioning and weighing shall be in 
accordance with sections 8.0 through 8.2 of this appendix and general 
guidance provided in reference 2 of section 13.0 of this appendix.
    6.9.1 Test for loose, surface particle contamination. After the 
initial weighing, install each test filter, in turn, in a filter 
cassette (Figures L-27, L-28, and L-29 of this appendix) and drop the 
cassette from a height of 25 cm to a flat hard surface, such as a 
particle-free wood bench. Repeat two times, for a total of three drop 
tests for each test filter. Remove the test filter from the cassette and 
weigh the filter. The average change in weight must be less than 20 
[micro]g.
    6.9.2 Test for temperature stability. After weighing each filter, 
place the test filters in a drying oven set at 40 [deg]C 2 [deg]C for not less than 48 hours. Remove, condition, 
and reweigh each test filter. The average change in weight must be less 
than 20 [micro]g.
    6.10 Alkalinity. Less than 25 microequivalents/gram of filter, as 
measured by the guidance given in reference 2 in section 13.0 of this 
appendix.
    6.11 Supplemental requirements. Although not required for 
determination of PM2.5 mass concentration under this 
reference method, additional specifications for the filter must be 
developed by users who intend to subject PM2.5 filter samples 
to subsequent chemical analysis. These supplemental specifications 
include background chemical contamination of the filter and any other 
filter parameters that may be required by the method of chemical 
analysis. All such supplemental filter specifications must be compatible 
with and

[[Page 97]]

secondary to the primary filter specifications given in this section 6.0 
of this appendix.
    7.0 PM2.5 Sampler.
    7.1 Configuration. The sampler shall consist of a sample air inlet, 
downtube, particle size separator (impactor), filter holder assembly, 
air pump and flow rate control system, flow rate measurement device, 
ambient and filter temperature monitoring system, barometric pressure 
measurement system, timer, outdoor environmental enclosure, and suitable 
mechanical, electrical, or electronic control capability to meet or 
exceed the design and functional performance as specified in this 
section 7.0 of this appendix. The performance specifications require 
that the sampler:
    (a) Provide automatic control of sample volumetric flow rate and 
other operational parameters.
    (b) Monitor these operational parameters as well as ambient 
temperature and pressure.
    (c) Provide this information to the sampler operator at the end of 
each sample period in digital form, as specified in table L-1 of section 
7.4.19 of this appendix.
    7.2 Nature of specifications. The PM2.5 sampler is 
specified by a combination of design and performance requirements. The 
sample inlet, downtube, particle size discriminator, filter cassette, 
and the internal configuration of the filter holder assembly are 
specified explicitly by design figures and associated mechanical 
dimensions, tolerances, materials, surface finishes, assembly 
instructions, and other necessary specifications. All other aspects of 
the sampler are specified by required operational function and 
performance, and the design of these other aspects (including the design 
of the lower portion of the filter holder assembly) is optional, subject 
to acceptable operational performance. Test procedures to demonstrate 
compliance with both the design and performance requirements are set 
forth in subpart E of part 53 of this chapter.
    7.3 Design specifications. Except as indicated in this section 7.3 
of this appendix, these components must be manufactured or reproduced 
exactly as specified, in an ISO 9001-registered facility, with 
registration initially approved and subsequently maintained during the 
period of manufacture. See Sec. 53.1(t) of this chapter for the 
definition of an ISO-registered facility. Minor modifications or 
variances to one or more components that clearly would not affect the 
aerodynamic performance of the inlet, downtube, impactor, or filter 
cassette will be considered for specific approval. Any such proposed 
modifications shall be described and submitted to the EPA for specific 
individual acceptability either as part of a reference or equivalent 
method application under part 53 of this chapter or in writing in 
advance of such an intended application under part 53 of this chapter.
    7.3.1 Sample inlet assembly. The sample inlet assembly, consisting 
of the inlet, downtube, and impactor shall be configured and assembled 
as indicated in Figure L-1 of this appendix and shall meet all 
associated requirements. A portion of this assembly shall also be 
subject to the maximum overall sampler leak rate specification under 
section 7.4.6 of this appendix.
    7.3.2 Inlet. The sample inlet shall be fabricated as indicated in 
Figures L-2 through L-18 of this appendix and shall meet all associated 
requirements.
    7.3.3 Downtube. The downtube shall be fabricated as indicated in 
Figure L-19 of this appendix and shall meet all associated requirements.
    7.3.4 Particle size separator. The sampler shall be configured with 
either one of the two alternative particle size separators described in 
this section 7.3.4. One separator is an impactor-type separator (WINS 
impactor) described in sections 7.3.4.1, 7.3.4.2, and 7.3.4.3 of this 
appendix. The alternative separator is a cyclone-type separator (VSCC 
\TM\) described in section 7.3.4.4 of this appendix.
    7.3.4.1 The impactor (particle size separator) shall be fabricated 
as indicated in Figures L-20 through L-24 of this appendix and shall 
meet all associated requirements. Following the manufacture and 
finishing of each upper impactor housing (Figure L-21 of this appendix), 
the dimension of the impaction jet must be verified by the manufacturer 
using Class ZZ go/no-go plug gauges that are traceable to NIST.
    7.3.4.2 Impactor filter specifications:
    (a) Size. Circular, 35 to 37 mm diameter.
    (b) Medium. Borosilicate glass fiber, without binder.
    (c) Pore size. 1 to 1.5 micrometer, as measured by ASTM F 316-80.
    (d) Thickness. 300 to 500 micrometers.
    7.3.4.3 Impactor oil specifications:
    (a) Composition. Dioctyl sebacate (DOS), single-compound diffusion 
oil.
    (b) Vapor pressure. Maximum 2 x 10-8 mm Hg at 25 [deg]C.
    (c) Viscosity. 36 to 40 centistokes at 25 [deg]C.
    (d) Density. 1.06 to 1.07 g/cm\3\ at 25 [deg]C.
    (e) Quantity. 1 mL 0.1 mL.
    7.3.4.4 The cyclone-type separator is identified as a BGI VSCC \TM\ 
Very Sharp Cut Cyclone particle size separator specified as part of EPA-
designated equivalent method EQPM-0202-142 (67 FR 15567, April 2, 2002) 
and as manufactured by BGI Incorporated, 58 Guinan Street, Waltham, 
Massachusetts 20451.
    7.3.5 Filter holder assembly. The sampler shall have a sample filter 
holder assembly to adapt and seal to the down tube and to hold and seal 
the specified filter, under section 6.0 of this appendix, in the sample 
air stream in a horizontal position below the downtube such that the 
sample air passes downward through the filter at a uniform face 
velocity.

[[Page 98]]

The upper portion of this assembly shall be fabricated as indicated in 
Figures L-25 and L-26 of this appendix and shall accept and seal with 
the filter cassette, which shall be fabricated as indicated in Figures 
L-27 through L-29 of this appendix.
    (a) The lower portion of the filter holder assembly shall be of a 
design and construction that:
    (1) Mates with the upper portion of the assembly to complete the 
filter holder assembly,
    (2) Completes both the external air seal and the internal filter 
cassette seal such that all seals are reliable over repeated filter 
changings, and
    (3) Facilitates repeated changing of the filter cassette by the 
sampler operator.
    (b) Leak-test performance requirements for the filter holder 
assembly are included in section 7.4.6 of this appendix.
    (c) If additional or multiple filters are stored in the sampler as 
part of an automatic sequential sample capability, all such filters, 
unless they are currently and directly installed in a sampling channel 
or sampling configuration (either active or inactive), shall be covered 
or (preferably) sealed in such a way as to:
    (1) Preclude significant exposure of the filter to possible 
contamination or accumulation of dust, insects, or other material that 
may be present in the ambient air, sampler, or sampler ventilation air 
during storage periods either before or after sampling; and
    (2) To minimize loss of volatile or semi-volatile PM sample 
components during storage of the filter following the sample period.
    7.3.6 Flow rate measurement adapter. A flow rate measurement adapter 
as specified in Figure L-30 of this appendix shall be furnished with 
each sampler.
    7.3.7 Surface finish. All internal surfaces exposed to sample air 
prior to the filter shall be treated electrolytically in a sulfuric acid 
bath to produce a clear, uniform anodized surface finish of not less 
than 1000 mg/ft\2\ (1.08 mg/cm\2\) in accordance with military standard 
specification (mil. spec.) 8625F, Type II, Class 1 in reference 4 of 
section 13.0 of this appendix. This anodic surface coating shall not be 
dyed or pigmented. Following anodization, the surfaces shall be sealed 
by immersion in boiling deionized water for not less than 15 minutes. 
Section 53.51(d)(2) of this chapter should also be consulted.
    7.3.8 Sampling height. The sampler shall be equipped with legs, a 
stand, or other means to maintain the sampler in a stable, upright 
position and such that the center of the sample air entrance to the 
inlet, during sample collection, is maintained in a horizontal plane and 
is 2.0 0.2 meters above the floor or other 
horizontal supporting surface. Suitable bolt holes, brackets, tie-downs, 
or other means should be provided to facilitate mechanically securing 
the sample to the supporting surface to prevent toppling of the sampler 
due to wind.
    7.4 Performance specifications.
    7.4.1 Sample flow rate. Proper operation of the impactor requires 
that specific air velocities be maintained through the device. 
Therefore, the design sample air flow rate through the inlet shall be 
16.67 L/min (1.000 m\3\/hour) measured as actual volumetric flow rate at 
the temperature and pressure of the sample air entering the inlet.
    7.4.2 Sample air flow rate control system. The sampler shall have a 
sample air flow rate control system which shall be capable of providing 
a sample air volumetric flow rate within the specified range, under 
section 7.4.1 of this appendix, for the specified filter, under section 
6.0 of this appendix, at any atmospheric conditions specified, under 
section 7.4.7 of this appendix, at a filter pressure drop equal to that 
of a clean filter plus up to 75 cm water column (55 mm Hg), and over the 
specified range of supply line voltage, under section 7.4.15.1 of this 
appendix. This flow control system shall allow for operator adjustment 
of the operational flow rate of the sampler over a range of at least 
15 percent of the flow rate specified in section 
7.4.1 of this appendix.
    7.4.3 Sample flow rate regulation. The sample flow rate shall be 
regulated such that for the specified filter, under section 6.0 of this 
appendix, at any atmospheric conditions specified, under section 7.4.7 
of this appendix, at a filter pressure drop equal to that of a clean 
filter plus up to 75 cm water column (55 mm Hg), and over the specified 
range of supply line voltage, under section 7.4.15.1 of this appendix, 
the flow rate is regulated as follows:
    7.4.3.1 The volumetric flow rate, measured or averaged over 
intervals of not more than 5 minutes over a 24-hour period, shall not 
vary more than 5 percent from the specified 16.67 
L/min flow rate over the entire sample period.
    7.4.3.2 The coefficient of variation (sample standard deviation 
divided by the mean) of the flow rate, measured over a 24-hour period, 
shall not be greater than 2 percent.
    7.4.3.3 The amplitude of short-term flow rate pulsations, such as 
may originate from some types of vacuum pumps, shall be attenuated such 
that they do not cause significant flow measurement error or affect the 
collection of particles on the particle collection filter.
    7.4.4 Flow rate cut off. The sampler's sample air flow rate control 
system shall terminate sample collection and stop all sample flow for 
the remainder of the sample period in the event that the sample flow 
rate deviates by more than 10 percent from the sampler design flow rate 
specified in section 7.4.1 of this appendix for more than 60 seconds. 
However, this sampler cut-off provision shall not apply during periods 
when the sampler is inoperative due to a temporary power interruption,

[[Page 99]]

and the elapsed time of the inoperative period shall not be included in 
the total sample time measured and reported by the sampler, under 
section 7.4.13 of this appendix.
    7.4.5 Flow rate measurement.
    7.4.5.1 The sampler shall provide a means to measure and indicate 
the instantaneous sample air flow rate, which shall be measured as 
volumetric flow rate at the temperature and pressure of the sample air 
entering the inlet, with an accuracy of 2 percent. 
The measured flow rate shall be available for display to the sampler 
operator at any time in either sampling or standby modes, and the 
measurement shall be updated at least every 30 seconds. The sampler 
shall also provide a simple means by which the sampler operator can 
manually start the sample flow temporarily during non-sampling modes of 
operation, for the purpose of checking the sample flow rate or the flow 
rate measurement system.
    7.4.5.2 During each sample period, the sampler's flow rate 
measurement system shall automatically monitor the sample volumetric 
flow rate, obtaining flow rate measurements at intervals of not greater 
than 30 seconds.
    (a) Using these interval flow rate measurements, the sampler shall 
determine or calculate the following flow-related parameters, scaled in 
the specified engineering units:
    (1) The instantaneous or interval-average flow rate, in L/min.
    (2) The value of the average sample flow rate for the sample period, 
in L/min.
    (3) The value of the coefficient of variation (sample standard 
deviation divided by the average) of the sample flow rate for the sample 
period, in percent.
    (4) The occurrence of any time interval during the sample period in 
which the measured sample flow rate exceeds a range of 5 percent of the average flow rate for the sample period 
for more than 5 minutes, in which case a warning flag indicator shall be 
set.
    (5) The value of the integrated total sample volume for the sample 
period, in m\3\.
    (b) Determination or calculation of these values shall properly 
exclude periods when the sampler is inoperative due to temporary 
interruption of electrical power, under section 7.4.13 of this appendix, 
or flow rate cut off, under section 7.4.4 of this appendix.
    (c) These parameters shall be accessible to the sampler operator as 
specified in table L-1 of section 7.4.19 of this appendix. In addition, 
it is strongly encouraged that the flow rate for each 5-minute interval 
during the sample period be available to the operator following the end 
of the sample period.
    7.4.6 Leak test capability.
    7.4.6.1 External leakage. The sampler shall include an external air 
leak-test capability consisting of components, accessory hardware, 
operator interface controls, a written procedure in the associated 
Operation/Instruction Manual, under section 7.4.18 of this appendix, and 
all other necessary functional capability to permit and facilitate the 
sampler operator to conveniently carry out a leak test of the sampler at 
a field monitoring site without additional equipment. The sampler 
components to be subjected to this leak test include all components and 
their interconnections in which external air leakage would or could 
cause an error in the sampler's measurement of the total volume of 
sample air that passes through the sample filter.
    (a) The suggested technique for the operator to use for this leak 
test is as follows:
    (1) Remove the sampler inlet and installs the flow rate measurement 
adapter supplied with the sampler, under section 7.3.6 of this appendix.
    (2) Close the valve on the flow rate measurement adapter and use the 
sampler air pump to draw a partial vacuum in the sampler, including (at 
least) the impactor, filter holder assembly (filter in place), flow 
measurement device, and interconnections between these devices, of at 
least 55 mm Hg (75 cm water column), measured at a location downstream 
of the filter holder assembly.
    (3) Plug the flow system downstream of these components to isolate 
the components under vacuum from the pump, such as with a built-in 
valve.
    (4) Stop the pump.
    (5) Measure the trapped vacuum in the sampler with a built-in 
pressure measuring device.
    (6) (i) Measure the vacuum in the sampler with the built-in pressure 
measuring device again at a later time at least 10 minutes after the 
first pressure measurement.
    (ii) Caution: Following completion of the test, the adaptor valve 
should be opened slowly to limit the flow rate of air into the sampler. 
Excessive air flow rate may blow oil out of the impactor.
    (7) Upon completion of the test, open the adaptor valve, remove the 
adaptor and plugs, and restore the sampler to the normal operating 
configuration.
    (b) The associated leak test procedure shall require that for 
successful passage of this test, the difference between the two pressure 
measurements shall not be greater than the number of mm of Hg specified 
for the sampler by the manufacturer, based on the actual internal volume 
of the sampler, that indicates a leak of less than 80 mL/min.
    (c) Variations of the suggested technique or an alternative external 
leak test technique may be required for samplers whose design or 
configuration would make the suggested technique impossible or 
impractical. The specific proposed external leak test procedure, or 
particularly an alternative leak

[[Page 100]]

test technique, proposed for a particular candidate sampler may be 
described and submitted to the EPA for specific individual acceptability 
either as part of a reference or equivalent method application under 
part 53 of this chapter or in writing in advance of such an intended 
application under part 53 of this chapter.
    7.4.6.2 Internal, filter bypass leakage. The sampler shall include 
an internal, filter bypass leak-check capability consisting of 
components, accessory hardware, operator interface controls, a written 
procedure in the Operation/Instruction Manual, and all other necessary 
functional capability to permit and facilitate the sampler operator to 
conveniently carry out a test for internal filter bypass leakage in the 
sampler at a field monitoring site without additional equipment. The 
purpose of the test is to determine that any portion of the sample flow 
rate that leaks past the sample filter without passing through the 
filter is insignificant relative to the design flow rate for the 
sampler.
    (a) The suggested technique for the operator to use for this leak 
test is as follows:
    (1) Carry out an external leak test as provided under section 
7.4.6.1 of this appendix which indicates successful passage of the 
prescribed external leak test.
    (2) Install a flow-impervious membrane material in the filter 
cassette, either with or without a filter, as appropriate, which 
effectively prevents air flow through the filter.
    (3) Use the sampler air pump to draw a partial vacuum in the 
sampler, downstream of the filter holder assembly, of at least 55 mm Hg 
(75 cm water column).
    (4) Plug the flow system downstream of the filter holder to isolate 
the components under vacuum from the pump, such as with a built-in 
valve.
    (5) Stop the pump.
    (6) Measure the trapped vacuum in the sampler with a built-in 
pressure measuring device.
    (7) Measure the vacuum in the sampler with the built-in pressure 
measuring device again at a later time at least 10 minutes after the 
first pressure measurement.
    (8) Remove the flow plug and membrane and restore the sampler to the 
normal operating configuration.
    (b) The associated leak test procedure shall require that for 
successful passage of this test, the difference between the two pressure 
measurements shall not be greater than the number of mm of Hg specified 
for the sampler by the manufacturer, based on the actual internal volume 
of the portion of the sampler under vacuum, that indicates a leak of 
less than 80 mL/min.
    (c) Variations of the suggested technique or an alternative 
internal, filter bypass leak test technique may be required for samplers 
whose design or configuration would make the suggested technique 
impossible or impractical. The specific proposed internal leak test 
procedure, or particularly an alternative internal leak test technique 
proposed for a particular candidate sampler may be described and 
submitted to the EPA for specific individual acceptability either as 
part of a reference or equivalent method application under part 53 of 
this chapter or in writing in advance of such intended application under 
part 53 of this chapter.
    7.4.7 Range of operational conditions. The sampler is required to 
operate properly and meet all requirements specified in this appendix 
over the following operational ranges.
    7.4.7.1 Ambient temperature. -30 to = 45 [deg]C (Note: Although for 
practical reasons, the temperature range over which samplers are 
required to be tested under part 53 of this chapter is -20 to = 40 
[deg]C, the sampler shall be designed to operate properly over this 
wider temperature range.).
    7.4.7.2 Ambient relative humidity. 0 to 100 percent.
    7.4.7.3 Barometric pressure range. 600 to 800 mm Hg.
    7.4.8 Ambient temperature sensor. The sampler shall have capability 
to measure the temperature of the ambient air surrounding the sampler 
over the range of -30 to = 45 [deg]C, with a resolution of 0.1 [deg]C 
and accuracy of 2.0 [deg]C, referenced as 
described in reference 3 in section 13.0 of this appendix, with and 
without maximum solar insolation.
    7.4.8.1 The ambient temperature sensor shall be mounted external to 
the sampler enclosure and shall have a passive, naturally ventilated sun 
shield. The sensor shall be located such that the entire sun shield is 
at least 5 cm above the horizontal plane of the sampler case or 
enclosure (disregarding the inlet and downtube) and external to the 
vertical plane of the nearest side or protuberance of the sampler case 
or enclosure. The maximum temperature measurement error of the ambient 
temperature measurement system shall be less than 1.6 [deg]C at 1 m/s 
wind speed and 1000 W/m2 solar radiation intensity.
    7.4.8.2 The ambient temperature sensor shall be of such a design and 
mounted in such a way as to facilitate its convenient dismounting and 
immersion in a liquid for calibration and comparison to the filter 
temperature sensor, under section 7.4.11 of this appendix.
    7.4.8.3 This ambient temperature measurement shall be updated at 
least every 30 seconds during both sampling and standby (non-sampling) 
modes of operation. A visual indication of the current (most recent) 
value of the ambient temperature measurement, updated at least every 30 
seconds, shall be available to the sampler operator during both sampling 
and standby (non-sampling) modes of operation, as specified in table L-1 
of section 7.4.19 of this appendix.

[[Page 101]]

    7.4.8.4 This ambient temperature measurement shall be used for the 
purpose of monitoring filter temperature deviation from ambient 
temperature, as required by section 7.4.11 of this appendix, and may be 
used for purposes of effecting filter temperature control, under section 
7.4.10 of this appendix, or computation of volumetric flow rate, under 
sections 7.4.1 to 7.4.5 of this appendix, if appropriate.
    7.4.8.5 Following the end of each sample period, the sampler shall 
report the maximum, minimum, and average temperature for the sample 
period, as specified in table L-1 of section 7.4.19 of this appendix.
    7.4.9 Ambient barometric sensor. The sampler shall have capability 
to measure the barometric pressure of the air surrounding the sampler 
over a range of 600 to 800 mm Hg referenced as described in reference 3 
in section 13.0 of this appendix; also see part 53, subpart E of this 
chapter. This barometric pressure measurement shall have a resolution of 
5 mm Hg and an accuracy of 10 mm Hg and shall be 
updated at least every 30 seconds. A visual indication of the value of 
the current (most recent) barometric pressure measurement, updated at 
least every 30 seconds, shall be available to the sampler operator 
during both sampling and standby (non-sampling) modes of operation, as 
specified in table L-1 of section 7.4.19 of this appendix. This 
barometric pressure measurement may be used for purposes of computation 
of volumetric flow rate, under sections 7.4.1 to 7.4.5 of this appendix, 
if appropriate. Following the end of a sample period, the sampler shall 
report the maximum, minimum, and mean barometric pressures for the 
sample period, as specified in table L-1 of section 7.4.19 of this 
appendix.
    7.4.10 Filter temperature control (sampling and post-sampling). The 
sampler shall provide a means to limit the temperature rise of the 
sample filter (all sample filters for sequential samplers), from 
insolation and other sources, to no more 5 [deg]C above the temperature 
of the ambient air surrounding the sampler, during both sampling and 
post-sampling periods of operation. The post-sampling period is the non-
sampling period between the end of the active sampling period and the 
time of retrieval of the sample filter by the sampler operator.
    7.4.11 Filter temperature sensor(s).
    7.4.11.1 The sampler shall have the capability to monitor the 
temperature of the sample filter (all sample filters for sequential 
samplers) over the range of -30 to = 45 [deg]C during both sampling and 
non-sampling periods. While the exact location of this temperature 
sensor is not explicitly specified, the filter temperature measurement 
system must demonstrate agreement, within 1 [deg]C, with a test 
temperature sensor located within 1 cm of the center of the filter 
downstream of the filter during both sampling and non-sampling modes, as 
specified in the filter temperature measurement test described in part 
53, subpart E of this chapter. This filter temperature measurement shall 
have a resolution of 0.1 [deg]C and accuracy of 1.0 [deg]C, referenced as described in reference 3 in 
section 13.0 of this appendix. This temperature sensor shall be of such 
a design and mounted in such a way as to facilitate its reasonably 
convenient dismounting and immersion in a liquid for calibration and 
comparison to the ambient temperature sensor under section 7.4.8 of this 
appendix.
    7.4.11.2 The filter temperature measurement shall be updated at 
least every 30 seconds during both sampling and standby (non-sampling) 
modes of operation. A visual indication of the current (most recent) 
value of the filter temperature measurement, updated at least every 30 
seconds, shall be available to the sampler operator during both sampling 
and standby (non-sampling) modes of operation, as specified in table L-1 
of section 7.4.19 of this appendix.
    7.4.11.3 For sequential samplers, the temperature of each filter 
shall be measured individually unless it can be shown, as specified in 
the filter temperature measurement test described in Sec. 53.57 of this 
chapter, that the temperature of each filter can be represented by fewer 
temperature sensors.
    7.4.11.4 The sampler shall also provide a warning flag indicator 
following any occurrence in which the filter temperature (any filter 
temperature for sequential samplers) exceeds the ambient temperature by 
more than 5 [deg]C for more than 30 consecutive minutes during either 
the sampling or post-sampling periods of operation, as specified in 
table L-1 of section 7.4.19 of this appendix, under section 10.12 of 
this appendix, regarding sample validity when a warning flag occurs. It 
is further recommended (not required) that the sampler be capable of 
recording the maximum differential between the measured filter 
temperature and the ambient temperature and its time and date of 
occurrence during both sampling and post-sampling (non-sampling) modes 
of operation and providing for those data to be accessible to the 
sampler operator following the end of the sample period, as suggested in 
table L-1 of section 7.4.19 of this appendix.
    7.4.12 Clock/timer system.
    (a) The sampler shall have a programmable real-time clock timing/
control system that:
    (1) Is capable of maintaining local time and date, including year, 
month, day-of-month, hour, minute, and second to an accuracy of 1.0 minute per month.
    (2) Provides a visual indication of the current system time, 
including year, month, day-of-month, hour, and minute, updated at least 
each minute, for operator verification.
    (3) Provides appropriate operator controls for setting the correct 
local time and date.

[[Page 102]]

    (4) Is capable of starting the sample collection period and sample 
air flow at a specific, operator-settable time and date, and stopping 
the sample air flow and terminating the sampler collection period 24 
hours (1440 minutes) later, or at a specific, operator-settable time and 
date.
    (b) These start and stop times shall be readily settable by the 
sampler operator to within 1.0 minute. The system 
shall provide a visual indication of the current start and stop time 
settings, readable to 1.0 minute, for verification 
by the operator, and the start and stop times shall also be available 
via the data output port, as specified in table L-1 of section 7.4.19 of 
this appendix. Upon execution of a programmed sample period start, the 
sampler shall automatically reset all sample period information and 
warning flag indications pertaining to a previous sample period. Refer 
also to section 7.4.15.4 of this appendix regarding retention of current 
date and time and programmed start and stop times during a temporary 
electrical power interruption.
    7.4.13 Sample time determination. The sampler shall be capable of 
determining the elapsed sample collection time for each PM2.5 
sample, accurate to within 1.0 minute, measured as 
the time between the start of the sampling period, under section 7.4.12 
of this appendix and the termination of the sample period, under section 
7.4.12 of this appendix or section 7.4.4 of this appendix. This elapsed 
sample time shall not include periods when the sampler is inoperative 
due to a temporary interruption of electrical power, under section 
7.4.15.4 of this appendix. In the event that the elapsed sample time 
determined for the sample period is not within the range specified for 
the required sample period in section 3.3 of this appendix, the sampler 
shall set a warning flag indicator. The date and time of the start of 
the sample period, the value of the elapsed sample time for the sample 
period, and the flag indicator status shall be available to the sampler 
operator following the end of the sample period, as specified in table 
L-1 of section 7.4.19 of this appendix.
    7.4.14 Outdoor environmental enclosure. The sampler shall have an 
outdoor enclosure (or enclosures) suitable to protect the filter and 
other non-weatherproof components of the sampler from precipitation, 
wind, dust, extremes of temperature and humidity; to help maintain 
temperature control of the filter (or filters, for sequential samplers); 
and to provide reasonable security for sampler components and settings.
    7.4.15 Electrical power supply.
    7.4.15.1 The sampler shall be operable and function as specified 
herein when operated on an electrical power supply voltage of 105 to 125 
volts AC (RMS) at a frequency of 59 to 61 Hz. Optional operation as 
specified at additional power supply voltages and/or frequencies shall 
not be precluded by this requirement.
    7.4.15.2 The design and construction of the sampler shall comply 
with all applicable National Electrical Code and Underwriters 
Laboratories electrical safety requirements.
    7.4.15.3 The design of all electrical and electronic controls shall 
be such as to provide reasonable resistance to interference or 
malfunction from ordinary or typical levels of stray electromagnetic 
fields (EMF) as may be found at various monitoring sites and from 
typical levels of electrical transients or electronic noise as may often 
or occasionally be present on various electrical power lines.
    7.4.15.4 In the event of temporary loss of electrical supply power 
to the sampler, the sampler shall not be required to sample or provide 
other specified functions during such loss of power, except that the 
internal clock/timer system shall maintain its local time and date 
setting within 1 minute per week, and the sampler 
shall retain all other time and programmable settings and all data 
required to be available to the sampler operator following each sample 
period for at least 7 days without electrical supply power. When 
electrical power is absent at the operator-set time for starting a 
sample period or is interrupted during a sample period, the sampler 
shall automatically start or resume sampling when electrical power is 
restored, if such restoration of power occurs before the operator-set 
stop time for the sample period.
    7.4.15.5 The sampler shall have the capability to record and retain 
a record of the year, month, day-of-month, hour, and minute of the start 
of each power interruption of more than 1 minute duration, up to 10 such 
power interruptions per sample period. (More than 10 such power 
interruptions shall invalidate the sample, except where an exceedance is 
measured, under section 3.3 of this appendix.) The sampler shall provide 
for these power interruption data to be available to the sampler 
operator following the end of the sample period, as specified in table 
L-1 of section 7.4.19 of this appendix.
    7.4.16 Control devices and operator interface. The sampler shall 
have mechanical, electrical, or electronic controls, control devices, 
electrical or electronic circuits as necessary to provide the timing, 
flow rate measurement and control, temperature control, data storage and 
computation, operator interface, and other functions specified. 
Operator-accessible controls, data displays, and interface devices shall 
be designed to be simple, straightforward, reliable, and easy to learn, 
read, and operate under field conditions. The sampler shall have 
provision for operator input and storage of up to 64 characters of 
numeric (or alphanumeric) data for purposes of site, sampler, and sample 
identification. This information shall be available to the sampler 
operator for verification and

[[Page 103]]

change and for output via the data output port along with other data 
following the end of a sample period, as specified in table L-1 of 
section 7.4.19 of this appendix. All data required to be available to 
the operator following a sample collection period or obtained during 
standby mode in a post-sampling period shall be retained by the sampler 
until reset, either manually by the operator or automatically by the 
sampler upon initiation of a new sample collection period.
    7.4.17 Data output port requirement. The sampler shall have a 
standard RS-232C data output connection through which digital data may 
be exported to an external data storage or transmission device. All 
information which is required to be available at the end of each sample 
period shall be accessible through this data output connection. The 
information that shall be accessible though this output port is 
summarized in table L-1 of section 7.4.19 of this appendix. Since no 
specific format for the output data is provided, the sampler 
manufacturer or vendor shall make available to sampler purchasers 
appropriate computer software capable of receiving exported sampler data 
and correctly translating the data into a standard spreadsheet format 
and optionally any other formats as may be useful to sampler users. This 
requirement shall not preclude the sampler from offering other types of 
output connections in addition to the required RS-232C port.
    7.4.18 Operation/instruction manual. The sampler shall include an 
associated comprehensive operation or instruction manual, as required by 
part 53 of this chapter, which includes detailed operating instructions 
on the setup, operation, calibration, and maintenance of the sampler. 
This manual shall provide complete and detailed descriptions of the 
operational and calibration procedures prescribed for field use of the 
sampler and all instruments utilized as part of this reference method. 
The manual shall include adequate warning of potential safety hazards 
that may result from normal use or malfunction of the method and a 
description of necessary safety precautions. The manual shall also 
include a clear description of all procedures pertaining to 
installation, operation, periodic and corrective maintenance, and 
troubleshooting, and shall include parts identification diagrams.
    7.4.19 Data reporting requirements. The various information that the 
sampler is required to provide and how it is to be provided is 
summarized in the following table L-1.

                                Table L-1 to Appendix L of Part 50--Summary of Information To Be Provided by the Sampler
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      Availability                                        Format
                                    Appendix L section -------------------------------------------------------------------------------------------------
    Information to be provided          reference                        End of        Visual      Data output
                                                         Anytime \1\   period \2\    display \3\       \4\      Digital reading \5\         Units
--------------------------------------------------------------------------------------------------------------------------------------------------------
Flow rate, 30-second maximum       7.4.5.1............      [check]   ............      [check]             *   XX.X...............  L/min
 interval.
Flow rate, average for the sample  7.4.5.2............            *       [check]             *       [check]   XX.X...............  L/min
 period.
Flow rate, CV, for sample period.  7.4.5.2............            *       [check]             *       [check]   XX.X...............  %
Flow rate, 5-min. average out of   7.4.5.2............      [check]       [check]       [check]   [check][squf  On/Off
 spec. (FLAG \6\).                                                                                          ]
Sample volume, total.............  7.4.5.2............            *       [check]       [check]       [check]   XX.X...............  m\3\
Temperature, ambient, 30-second    7.4.8..............      [check]   ............      [check]   ............  XX.X...............  [deg]C
 interval.
Temperature, ambient, min., max.,  7.4.8..............            *       [check]       [check]   [check][squf  XX.X...............  [deg]C
 average for the sample period.                                                                             ]
Baro. pressure, ambient, 30-       7.4.9..............      [check]   ............      [check]   ............  XXX................  mm Hg
 second interval.
Baro. pressure, ambient, min.,     7.4.9..............            *       [check]       [check]   [check][squf  XXX................  mm Hg
 max., average for the sample                                                                               ]
 period.
Filter temperature, 30-second      7.4.11.............      [check]   ............      [check]   ............  XX.X...............  [deg]C
 interval.

[[Page 104]]

 
Filter temp. differential, 30-     7.4.11.............            *       [check]       [check]   [check][squf  On/Off
 second interval, out of spec.                                                                              ]
 (FLAG \6\).
Filter temp., maximum              7.4.11.............            *             *             *             *   X.X, YY/MM/DD HH.mm  [deg]C, Yr/Mon/Day
 differential from ambient, date,                                                                                                     Hrs. min
 time of occurrence.
Date and Time....................  7.4.12.............      [check]   ............      [check]   ............  YY/MM/DD HH.mm.....  Yr/Mon/Day Hrs. min
Sample start and stop time         7.4.12.............      [check]       [check]       [check]       [check]   YY/MM/DD HH.mm.....  Yr/Mon/Day Hrs. min
 settings.
Sample period start time.........  7.4.12.............  ............      [check]       [check]       [check]   YY/MM/DD HH.mm.....  Yr/Mon/Day Hrs. min
Elapsed sample time..............  7.4.13.............            *       [check]       [check]       [check]   HH.mm..............  Hrs. min
Elapsed sample time, out of spec.  7.4.13.............  ............      [check]       [check]   [check][squf  On/Off
 (FLAG \6\).                                                                                                ]
Power interruptions <=1 min.,      7.4.15.5...........            *       [check]             *       [check]   1HH.mm, 2HH.mm,      Hrs. min
 start time of first 10.                                                                                         etc..
User-entered information, such as  7.4.16.............      [check]       [check]       [check]   [check][squf  As entered ........
 sampler and site identification.                                                                           ]
--------------------------------------------------------------------------------------------------------------------------------------------------------
[check] Provision of this information is required.
* Provision of this information is optional. If information related to the entire sample period is optionally provided prior to the end of the sample
  period, the value provided should be the value calculated for the portion of the sampler period completed up to the time the information is provided.
[squf] Indicates that this information is also required to be provided to the Air Quality System (AQS) data bank; see Sec. 58.16 of this chapter. For
  ambient temperature and barometric pressure, only the average for the sample period must be reported.
1. Information is required to be available to the operator at any time the sampler is operating, whether sampling or not.
2. Information relates to the entire sampler period and must be provided following the end of the sample period until reset manually by the operator or
  automatically by the sampler upon the start of a new sample period.
3. Information shall be available to the operator visually.
4. Information is to be available as digital data at the sampler's data output port specified in section 7.4.16 of this appendix following the end of
  the sample period until reset manually by the operator or automatically by the sampler upon the start of a new sample period.
5. Digital readings, both visual and data output, shall have not less than the number of significant digits and resolution specified.
6. Flag warnings may be displayed to the operator by a single flag indicator or each flag may be displayed individually. Only a set (on) flag warning
  must be indicated; an off (unset) flag may be indicated by the absence of a flag warning. Sampler users should refer to section 10.12 of this appendix
  regarding the validity of samples for which the sampler provided an associated flag warning.

    8.0 Filter Weighing. See reference 2 in section 13.0 of this 
appendix, for additional, more detailed guidance.
    8.1 Analytical balance. The analytical balance used to weigh filters 
must be suitable for weighing the type and size of filters specified, 
under section 6.0 of this appendix, and have a readability of 1 [micro]g. The balance shall be calibrated as specified 
by the manufacturer at installation and recalibrated immediately prior 
to each weighing session. See reference 2 in section 13.0 of this 
appendix for additional guidance.
    8.2 Filter conditioning. All sample filters used shall be 
conditioned immediately before both the pre- and post-sampling weighings 
as specified below. See reference 2 in section 13.0 of this appendix for 
additional guidance.
    8.2.1 Mean temperature. 20 - 23 [deg]C.
    8.2.2 Temperature control. 2 [deg]C over 24 
hours.
    8.2.3 Mean humidity. Generally, 30-40 percent relative humidity; 
however, where it can be shown that the mean ambient relative humidity 
during sampling is less than 30 percent, conditioning is permissible at 
a mean

[[Page 105]]

relative humidity within 5 relative humidity 
percent of the mean ambient relative humidity during sampling, but not 
less than 20 percent.
    8.2.4 Humidity control. 5 relative humidity 
percent over 24 hours.
    8.2.5 Conditioning time. Not less than 24 hours.
    8.3 Weighing procedure.
    8.3.1 New filters should be placed in the conditioning environment 
immediately upon arrival and stored there until the pre-sampling 
weighing. See reference 2 in section 13.0 of this appendix for 
additional guidance.
    8.3.2 The analytical balance shall be located in the same controlled 
environment in which the filters are conditioned. The filters shall be 
weighed immediately following the conditioning period without 
intermediate or transient exposure to other conditions or environments.
    8.3.3 Filters must be conditioned at the same conditions (humidity 
within 5 relative humidity percent) before both 
the pre- and post-sampling weighings.
    8.3.4 Both the pre- and post-sampling weighings should be carried 
out on the same analytical balance, using an effective technique to 
neutralize static charges on the filter, under reference 2 in section 
13.0 of this appendix. If possible, both weighings should be carried out 
by the same analyst.
    8.3.5 The pre-sampling (tare) weighing shall be within 30 days of 
the sampling period.
    8.3.6 The post-sampling conditioning and weighing shall be completed 
within 240 hours (10 days) after the end of the sample period, unless 
the filter sample is maintained at temperatures below the average 
ambient temperature during sampling (or 4 [deg]C or below for average 
sampling temperatures less than 4 [deg]C) during the time between 
retrieval from the sampler and the start of the conditioning, in which 
case the period shall not exceed 30 days. Reference 2 in section 13.0 of 
this appendix has additional guidance on transport of cooled filters.
    8.3.7 Filter blanks.
    8.3.7.1 New field blank filters shall be weighed along with the pre-
sampling (tare) weighing of each lot of PM2.5 filters. These 
blank filters shall be transported to the sampling site, installed in 
the sampler, retrieved from the sampler without sampling, and reweighed 
as a quality control check.
    8.3.7.2 New laboratory blank filters shall be weighed along with the 
pre-sampling (tare) weighing of each set of PM2.5 filters. 
These laboratory blank filters should remain in the laboratory in 
protective containers during the field sampling and should be reweighed 
as a quality control check.
    8.3.8 Additional guidance for proper filter weighing and related 
quality assurance activities is provided in reference 2 in section 13.0 
of this appendix.
    9.0 Calibration. Reference 2 in section 13.0 of this appendix 
contains additional guidance.
    9.1 General requirements.
    9.1.1 Multipoint calibration and single-point verification of the 
sampler's flow rate measurement device must be performed periodically to 
establish and maintain traceability of subsequent flow measurements to a 
flow rate standard.
    9.1.2 An authoritative flow rate standard shall be used for 
calibrating or verifying the sampler's flow rate measurement device with 
an accuracy of 2 percent. The flow rate standard 
shall be a separate, stand-alone device designed to connect to the flow 
rate measurement adapter, Figure L-30 of this appendix. This flow rate 
standard must have its own certification and be traceable to a National 
Institute of Standards and Technology (NIST) primary standard for volume 
or flow rate. If adjustments to the sampler's flow rate measurement 
system calibration are to be made in conjunction with an audit of the 
sampler's flow measurement system, such adjustments shall be made 
following the audit. Reference 2 in section 13.0 of this appendix 
contains additional guidance.
    9.1.3 The sampler's flow rate measurement device shall be re-
calibrated after electromechanical maintenance or transport of the 
sampler.
    9.2 Flow rate calibration/verification procedure.
    9.2.1 PM2.5 samplers may employ various types of flow 
control and flow measurement devices. The specific procedure used for 
calibration or verification of the flow rate measurement device will 
vary depending on the type of flow rate controller and flow rate 
measurement employed. Calibration shall be in terms of actual ambient 
volumetric flow rates (Q\a\), measured at the sampler's inlet downtube. 
The generic procedure given here serves to illustrate the general steps 
involved in the calibration of a PM2.5 sampler. The sampler 
operation/instruction manual required under section 7.4.18 of this 
appendix and the Quality Assurance Handbook in reference 2 in section 
13.0 of this appendix provide more specific and detailed guidance for 
calibration.
    9.2.2 The flow rate standard used for flow rate calibration shall 
have its own certification and be traceable to a NIST primary standard 
for volume or flow rate. A calibration relationship for the flow rate 
standard, e.g., an equation, curve, or family of curves relating actual 
flow rate (Qa) to the flow rate indicator reading, shall be 
established that is accurate to within 2 percent over the expected range 
of ambient temperatures and pressures at which the flow rate standard 
may be used. The flow rate standard must be re-calibrated or re-verified 
at least annually.
    9.2.3 The sampler flow rate measurement device shall be calibrated 
or verified by removing the sampler inlet and connecting the

[[Page 106]]

flow rate standard to the sampler's downtube in accordance with the 
operation/instruction manual, such that the flow rate standard 
accurately measures the sampler's flow rate. The sampler operator shall 
first carry out a sampler leak check and confirm that the sampler passes 
the leak test and then verify that no leaks exist between the flow rate 
standard and the sampler.
    9.2.4 The calibration relationship between the flow rate (in actual 
L/min) indicated by the flow rate standard and by the sampler's flow 
rate measurement device shall be established or verified in accordance 
with the sampler operation/instruction manual. Temperature and pressure 
corrections to the flow rate indicated by the flow rate standard may be 
required for certain types of flow rate standards. Calibration of the 
sampler's flow rate measurement device shall consist of at least three 
separate flow rate measurements (multipoint calibration) evenly spaced 
within the range of -10 percent to = 10 percent of the sampler's 
operational flow rate, section 7.4.1 of this appendix. Verification of 
the sampler's flow rate shall consist of one flow rate measurement at 
the sampler's operational flow rate. The sampler operation/instruction 
manual and reference 2 in section 13.0 of this appendix provide 
additional guidance.
    9.2.5 If during a flow rate verification the reading of the 
sampler's flow rate indicator or measurement device differs by 4 percent or more from the flow rate measured by the 
flow rate standard, a new multipoint calibration shall be performed and 
the flow rate verification must then be repeated.
    9.2.6 Following the calibration or verification, the flow rate 
standard shall be removed from the sampler and the sampler inlet shall 
be reinstalled. Then the sampler's normal operating flow rate (in L/min) 
shall be determined with a clean filter in place. If the flow rate 
indicated by the sampler differs by 2 percent or 
more from the required sampler flow rate, the sampler flow rate must be 
adjusted to the required flow rate, under section 7.4.1 of this 
appendix.
    9.3 Periodic calibration or verification of the calibration of the 
sampler's ambient temperature, filter temperature, and barometric 
pressure measurement systems is also required. Reference 3 of section 
13.0 of this appendix contains additional guidance.
    10.0 PM2.5 Measurement Procedure. The detailed procedure 
for obtaining valid PM2.5 measurements with each specific 
sampler designated as part of a reference method for PM2.5 
under part 53 of this chapter shall be provided in the sampler-specific 
operation or instruction manual required by section 7.4.18 of this 
appendix. Supplemental guidance is provided in section 2.12 of the 
Quality Assurance Handbook listed in reference 2 in section 13.0 of this 
appendix. The generic procedure given here serves to illustrate the 
general steps involved in the PM2.5 sample collection and 
measurement, using a PM2.5 reference method sampler.
    10.1 The sampler shall be set up, calibrated, and operated in 
accordance with the specific, detailed guidance provided in the specific 
sampler's operation or instruction manual and in accordance with a 
specific quality assurance program developed and established by the 
user, based on applicable supplementary guidance provided in reference 2 
in section 13.0 of this appendix.
    10.2 Each new sample filter shall be inspected for correct type and 
size and for pinholes, particles, and other imperfections. Unacceptable 
filters should be discarded. A unique identification number shall be 
assigned to each filter, and an information record shall be established 
for each filter. If the filter identification number is not or cannot be 
marked directly on the filter, alternative means, such as a number-
identified storage container, must be established to maintain positive 
filter identification.
    10.3 Each filter shall be conditioned in the conditioning 
environment in accordance with the requirements specified in section 8.2 
of this appendix.
    10.4 Following conditioning, each filter shall be weighed in 
accordance with the requirements specified in section 8.0 of this 
appendix and the presampling weight recorded with the filter 
identification number.
    10.5 A numbered and preweighed filter shall be installed in the 
sampler following the instructions provided in the sampler operation or 
instruction manual.
    10.6 The sampler shall be checked and prepared for sample collection 
in accordance with instructions provided in the sampler operation or 
instruction manual and with the specific quality assurance program 
established for the sampler by the user.
    10.7 The sampler's timer shall be set to start the sample collection 
at the beginning of the desired sample period and stop the sample 
collection 24 hours later.
    10.8 Information related to the sample collection (site location or 
identification number, sample date, filter identification number, and 
sampler model and serial number) shall be recorded and, if appropriate, 
entered into the sampler.
    10.9 The sampler shall be allowed to collect the PM2.5 
sample during the set 24-hour time period.
    10.10 Within 177 hours (7 days, 9 hours) of the end of the sample 
collection period, the filter, while still contained in the filter 
cassette, shall be carefully removed from the sampler, following the 
procedure provided in the sampler operation or instruction manual and 
the quality assurance program, and placed in a protective container. The 
protective container shall contain no loose material that could be 
transferred to the filter. The protective container shall hold the 
filter

[[Page 107]]

cassette securely such that the cover shall not come in contact with the 
filter's surfaces. Reference 2 in section 13.0 of this appendix contains 
additional information.
    10.11 The total sample volume in actual m\3\ for the sampling period 
and the elapsed sample time shall be obtained from the sampler and 
recorded in accordance with the instructions provided in the sampler 
operation or instruction manual. All sampler warning flag indications 
and other information required by the local quality assurance program 
shall also be recorded.
    10.12 All factors related to the validity or representativeness of 
the sample, such as sampler tampering or malfunctions, unusual 
meteorological conditions, construction activity, fires or dust storms, 
etc. shall be recorded as required by the local quality assurance 
program. The occurrence of a flag warning during a sample period shall 
not necessarily indicate an invalid sample but rather shall indicate the 
need for specific review of the QC data by a quality assurance officer 
to determine sample validity.
    10.13 After retrieval from the sampler, the exposed filter 
containing the PM2.5 sample should be transported to the 
filter conditioning environment as soon as possible, ideally to arrive 
at the conditioning environment within 24 hours for conditioning and 
subsequent weighing. During the period between filter retrieval from the 
sampler and the start of the conditioning, the filter shall be 
maintained as cool as practical and continuously protected from exposure 
to temperatures over 25 [deg]C to protect the integrity of the sample 
and minimize loss of volatile components during transport and storage. 
See section 8.3.6 of this appendix regarding time limits for completing 
the post-sampling weighing. See reference 2 in section 13.0 of this 
appendix for additional guidance on transporting filter samplers to the 
conditioning and weighing laboratory.
    10.14. The exposed filter containing the PM2.5 sample 
shall be re-conditioned in the conditioning environment in accordance 
with the requirements specified in section 8.2 of this appendix.
    10.15. The filter shall be reweighed immediately after conditioning 
in accordance with the requirements specified in section 8.0 of this 
appendix, and the postsampling weight shall be recorded with the filter 
identification number.
    10.16 The PM2.5 concentration shall be calculated as 
specified in section 12.0 of this appendix.
    11.0 Sampler Maintenance. The sampler shall be maintained as 
described by the sampler's manufacturer in the sampler-specific 
operation or instruction manual required under section 7.4.18 of this 
appendix and in accordance with the specific quality assurance program 
developed and established by the user based on applicable supplementary 
guidance provided in reference 2 in section 13.0 of this appendix.
    12.0 Calculations
    12.1 (a) The PM2.5 concentration is calculated as:

PM2.5 = (Wf - Wi)/Va

where:

PM2.5 = mass concentration of PM2.5, [micro]g/
          m\3\;
Wf, Wi = final and initial weights, respectively, 
          of the filter used to collect the PM2.5 particle 
          sample, [micro]g;
Va = total air volume sampled in actual volume units, as 
          provided by the sampler, m\3\.

    Note: Total sample time must be between 1,380 and 1,500 minutes (23 
and 25 hrs) for a fully valid PM2.5 sample; however, see also 
section 3.3 of this appendix.

    13.0 References.
    1. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume I, Principles. EPA/600/R-94/038a, April 1994. Available from 
CERI, ORD Publications, U.S. Environmental Protection Agency, 26 West 
Martin Luther King Drive, Cincinnati, Ohio 45268.
    2. Quality Assurance Guidance Document 2.12. Monitoring 
PM2.5 in Ambient Air Using Designated Reference or Class I 
Equivalent Methods. U.S. EPA, National Exposure Research Laboratory. 
Research Triangle Park, NC, November 1988 or later edition. Currently 
available at: http://www.epa.gov/ttn/amtic/pmqainf.html.
    3. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume IV: Meteorological Measurements, (Revised Edition) EPA/600/R-94/
038d, March, 1995. Available from CERI, ORD Publications, U.S. 
Environmental Protection Agency, 26 West Martin Luther King Drive, 
Cincinnati, Ohio 45268.
    4. Military standard specification (mil. spec.) 8625F, Type II, 
Class 1 as listed in Department of Defense Index of Specifications and 
Standards (DODISS), available from DODSSP-Customer Service, 
Standardization Documents Order Desk, 700 Robbins Avenue, Building 4D, 
Philadelphia, PA 1911-5094.
    14.0 Figures L-1 through L-30 to Appendix L.

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[62 FR 38714, July 18, 1997, as amended at 64 FR 19719, Apr. 22, 1999; 
71 FR 61226, Oct. 17, 2006]

[[Page 138]]



                  Sec. Appendix M to Part 50 [Reserved]



 Sec. Appendix N to Part 50--Interpretation of the National Ambient Air 
                 Quality Standards for PM2.5

                               1.0 General

    (a) This appendix explains the data handling conventions and 
computations necessary for determining when the national ambient air 
quality standards (NAAQS) for PM2.5 are met, specifically the 
primary and secondary annual and 24-hour PM2.5 NAAQS 
specified in Sec. 50.7, 50.13, and 50.18. PM2.5 is defined, 
in general terms, as particles with an aerodynamic diameter less than or 
equal to a nominal 2.5 micrometers. PM2.5 mass concentrations 
are measured in the ambient air by a Federal Reference Method (FRM) 
based on appendix L of this part, as applicable, and designated in 
accordance with part 53 of this chapter; or by a Federal Equivalent 
Method (FEM) designated in accordance with part 53 of this chapter; or 
by an Approved Regional Method (ARM) designated in accordance with part 
58 of this chapter. Only those FRM, FEM, and ARM measurements that are 
derived in accordance with part 58 of this chapter (i.e., that are 
deemed ``suitable'') shall be used in comparisons with the 
PM2.5 NAAQS. The data handling and computation procedures to 
be used to construct annual and 24-hour NAAQS metrics from reported 
PM2.5 mass concentrations, and the associated instructions 
for comparing these calculated metrics to the levels of the 
PM2.5 NAAQS, are specified in sections 2.0, 3.0, and 4.0 of 
this appendix.
    (b) Decisions to exclude, retain, or make adjustments to the data 
affected by exceptional events, including natural events, are made 
according to the requirements and process deadlines specified in 
Sec. Sec. 50.1, 50.14 and 51.930 of this chapter.
    (c) The terms used in this appendix are defined as follows:
    Annual mean refers to a weighted arithmetic mean, based on quarterly 
means, as defined in section 4.4 of this appendix.
    The Air Quality System (AQS) is EPA's official repository of ambient 
air data.
    Collocated monitors refers to two or more air measurement 
instruments for the same parameter (e.g., PM2.5 mass) 
operated at the same site location, and whose placement is consistent 
with Sec. 53.1 of this chapter. For purposes of considering a combined 
site record in this appendix, when two or more monitors are operated at 
the same site, one monitor is designated as the ``primary'' monitor with 
any additional monitors designated as ``collocated.'' It is implicit in 
these appendix procedures that the primary monitor and collocated 
monitor(s) are all deemed suitable for the applicable NAAQS comparison; 
however, it is not a requirement that the primary and monitors utilize 
the same specific sampling and analysis method.
    Combined site data record is the data set used for performing 
calculations in appendix N. It represents data for the primary monitors 
augmented with data from collocated monitors according to the procedure 
specified in section 3.0(d) of this appendix.
    Creditable samples are daily values in the combined site record that 
are given credit for data completeness. The number of creditable samples 
(cn) for a given year also governs which value in the sorted series of 
daily values represents the 98th percentile for that year. Creditable 
samples include daily values collected on scheduled sampling days and 
valid make-up samples taken for missed or invalidated samples on 
scheduled sampling days.
    Daily values refer to the 24-hour average concentrations of 
PM2.5 mass measured (or averaged from hourly measurements in 
AQS) from midnight to midnight (local standard time) from suitable 
monitors.
    Data substitution tests are diagnostic evaluations performed on an 
annual PM2.5 NAAQS design value (DV) or a 24-hour 
PM2.5 NAAQS DV to determine if those metrics, which are 
judged to be based on incomplete data in accordance with 4.1(b) or 
4.2(b) of this appendix shall nevertheless be deemed valid for NAAQS 
comparisons, or alternatively, shall still be considered incomplete and 
not valid for NAAQS comparisons. There are two data substitution tests, 
the ``minimum quarterly value'' test and the ``maximum quarterly value'' 
test. Design values (DVs) are the 3-year average NAAQS metrics that are 
compared to the NAAQS levels to determine when a monitoring site meets 
or does not meet the NAAQS, calculated as shown in section 4. There are 
two separate DVs specified in this appendix:
    (1) The 3-year average of PM2.5 annual mean mass 
concentrations for each eligible monitoring site is referred to as the 
``annual PM2.5 NAAQS DV''.
    (2) The 3-year average of annual 98th percentile 24-hour average 
PM2.5 mass concentration values recorded at each eligible 
monitoring site is referred to as the ``24-hour (or daily) PM2.5 NAAQS 
DV''.
    Eligible sites are monitoring stations that meet the criteria 
specified in Sec. 58.11 and Sec. 58.30 of this chapter, and thus are 
approved for comparison to the annual PM2.5 NAAQS. For the 
24-hour PM2.5 NAAQS, all site locations that meet the 
criteria specified in Sec. 58.11 are approved (i.e., eligible) for 
NAAQS comparisons.
    Extra samples are non-creditable samples. They are daily values that 
do not occur on scheduled sampling days and that cannot be used as make-
up samples for missed or invalidated scheduled samples. Extra samples

[[Page 139]]

are used in mean calculations and are included in the series of all 
daily values subject to selection as a 98th percentile value, but are 
not used to determine which value in the sorted list represents the 98th 
percentile.
    Make-up samples are samples collected to take the place of missed or 
invalidated required scheduled samples. Make-up samples can be made by 
either the primary or the collocated monitor. Make-up samples are either 
taken before the next required sampling day or exactly one week after 
the missed (or voided) sampling day.
    The maximum quarterly value data substitution test substitutes 
actual ``high'' reported daily PM2.5 values from the same 
site (specifically, the highest reported non-excluded quarterly value(s) 
(year non-specific) contained in the combined site record for the 
evaluated 3-year period) for missing daily values.
    The minimum quarterly value data substitution test substitutes 
actual ``low'' reported daily PM2.5 values from the same site 
(specifically, the lowest reported quarterly value(s) (year non-
specific) contained in the combined site record for the evaluated 3-year 
period) for missing daily values.
    98th percentile is the smallest daily value out of a year of 
PM2.5 mass monitoring data below which no more than 98 
percent of all daily values fall using the ranking and selection method 
specified in section 4.5(a) of this appendix.
    Primary monitors are suitable monitors designated by a state or 
local agency in their annual network plan (and in AQS) as the default 
data source for creating a combined site record for purposes of NAAQS 
comparisons. If there is only one suitable monitor at a particular site 
location, then it is presumed to be a primary monitor.
    Quarter refers to a calendar quarter (e.g., January through March).
    Quarterly data capture rate is the percentage of scheduled samples 
in a calendar quarter that have corresponding valid reported sample 
values. Quarterly data capture rates are specifically calculated as the 
number of creditable samples for the quarter divided by the number of 
scheduled samples for the quarter, the result then multiplied by 100 and 
rounded to the nearest integer.
    Scheduled PM2.5 samples refers to those reported daily values which 
are consistent with the required sampling frequency (per Sec. 58.12 of 
this chapter) for the primary monitor, or those that meet the special 
exception noted in section 3.0(e) of this appendix.
    Seasonal sampling is the practice of collecting data at a reduced 
frequency during a season of expected low concentrations.
    Suitable monitors are instruments that use sampling and analysis 
methods approved for NAAQS comparisons. For the annual and 24-hour 
PM2.5 NAAQS, suitable monitors include all FRMs, and all 
FEMs/ARMs except those specific continuous FEMs/ARMs disqualified by a 
particular monitoring agency network in accordance with Sec. 
58.10(b)(13) and approved by the EPA Regional Administrator per Sec. 
58.11(e) of this chapter.
    Test design values (TDV) are numerical values that used in the data 
substitution tests described in sections 4.1(c)(i), 4.1(c)(ii) and 
4.2(c)(i) of this appendix to determine if the PM2.5 NAAQS DV 
with incomplete data are judged to be valid for NAAQS comparisons. There 
are two TDVs: TDVmin to determine if the NAAQS is not met and 
is used in the ``minimum quarterly value'' data substitution test and 
TDVmax to determine if the NAAQS is met and is used in the 
``maximum quarterly value'' data substitution test. These TDV's are 
derived by substituting historically low or historically high daily 
concentration values for missing data in an incomplete year(s).
    Year refers to a calendar year.

                      2.0 Monitoring Considerations

    (a) Section 58.30 of this chapter provides special considerations 
for data comparisons to the annual PM2.5 NAAQS.
    (b) Monitors meeting the network technical requirements detailed in 
Sec. 58.11 of this chapter are suitable for comparison with the NAAQS 
for PM2.5.
    (c) Section 58.12 of this chapter specifies the required minimum 
frequency of sampling for PM2.5. Exceptions to the specified 
sampling frequencies, such as seasonal sampling, are subject to the 
approval of the EPA Regional Administrator and must be documented in the 
state or local agency Annual Monitoring Network Plan as required in 
Sec. 58.10 of this chapter and also in AQS.

 3.0 Requirements for Data Use and Data Reporting for Comparisons With 
                     the NAAQS for PM2.5

    (a) Except as otherwise provided in this appendix, all valid FRM/
FEM/ARM PM2.5 mass concentration data produced by suitable 
monitors that are required to be submitted to AQS, or otherwise 
available to EPA, meeting the requirements of part 58 of this chapter 
including appendices A, C, and E shall be used in the DV calculations. 
Generally, EPA will only use such data if they have been certified by 
the reporting organization (as prescribed by Sec. 58.15 of this 
chapter); however, data not certified by the reporting organization can 
nevertheless be used, if the deadline for certification has passed and 
EPA judges the data to be complete and accurate.
    (b) PM2.5 mass concentration data (typically collected 
hourly for continuous instruments and daily for filter-based 
instruments) shall be reported to AQS in micrograms per cubic meter 
([micro]g/m\3\) to at least one decimal place. If concentrations are 
reported to one

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decimal place, additional digits to the right of the tenths decimal 
place shall be truncated. If concentrations are reported to AQS with 
more than one decimal place, AQS will truncate the value to one decimal 
place for NAAQS usage (i.e., for implementing the procedures in this 
appendix). In situations where suitable PM2.5 data are 
available to EPA but not reported to AQS, the same truncation protocol 
shall be applied to that data. In situations where PM2.5 mass 
data are submitted to AQS, or are otherwise available, with less 
precision than specified above, these data shall nevertheless still be 
deemed appropriate for NAAQS usage.
    (c) Twenty-four-hour average concentrations will be computed in AQS 
from submitted hourly PM2.5 concentration data for each 
corresponding day of the year and the result will be stored in the 
first, or start, hour (i.e., midnight, hour `0') of the 24-hour period. 
A 24-hour average concentration shall be considered valid if at least 75 
percent of the hourly averages (i.e., 18 hourly values) for the 24-hour 
period are available. In the event that less than all 24 hourly average 
concentrations are available (i.e., less than 24, but at least 18), the 
24-hour average concentration shall be computed on the basis of the 
hours available using the number of available hours within the 24-hour 
period as the divisor (e.g., 19, if 19 hourly values are available). 
Twenty-four-hour periods with seven or more missing hours shall also be 
considered valid if, after substituting zero for all missing hourly 
concentrations, the resulting 24-hour average daily value is greater 
than the level of the 24-hour PM2.5 NAAQS (i.e., greater than 
or equal to 35.5 [micro]g/m\3\). Twenty-four hour average 
PM2.5 mass concentrations that are averaged in AQS from 
hourly values will be truncated to one decimal place, consistent with 
the data handling procedure for the reported hourly (and also 24-hour 
filter-based) data.
    (d) All calculations shown in this appendix shall be implemented on 
a site-level basis. Site level concentration data shall be processed as 
follows:
    (1) The default dataset for PM2.5 mass concentrations for 
a site shall consist of the measured concentrations recorded from the 
designated primary monitor(s). All daily values produced by the primary 
monitor are considered part of the site record; this includes all 
creditable samples and all extra samples.
    (2) Data for the primary monitors shall be augmented as much as 
possible with data from collocated monitors. If a valid daily value is 
not produced by the primary monitor for a particular day (scheduled or 
otherwise), but a value is available from a collocated monitor, then 
that collocated value shall be considered part of the combined site data 
record. If more than one collocated daily value is available, the 
average of those valid collocated values shall be used as the daily 
value. The data record resulting from this procedure is referred to as 
the ``combined site data record.''
    (e) All daily values in a combined site data record are used in the 
calculations specified in this appendix; however, not all daily values 
are given credit towards data completeness requirements. Only creditable 
samples are given credit for data completeness. Creditable samples 
include daily values in the combined site record that are collected on 
scheduled sampling days and valid make-up samples taken for missed or 
invalidated samples on scheduled sampling days. Days are considered 
scheduled according to the required sampling frequency of the designated 
primary monitor with one exception. The exception is, if a collocated 
continuous FEM/ARM monitor has a more intensive sampling frequency than 
the primary FRM monitor, then samples contributed to the combined site 
record from that continuous FEM/ARM monitor are always considered 
scheduled and, hence, also creditable. Daily values in the combined site 
data record that are reported for nonscheduled days, but that are not 
valid make-up samples are referred to as extra samples.

   4.0 Comparisons With the Annual and 24-Hour PM2.5 NAAQS

                         4.1 Annual PM2.5 NAAQS

    (a) The primary annual PM2.5 NAAQS is met when the annual 
PM2.5 NAAQS DV is less than or equal to 12.0 [micro]g/m\3\ at 
each eligible monitoring site. The secondary annual PM2.5 
NAAQS is met when the annual PM2.5 NAAQS DV is less than or 
equal to 15.0 [micro]g/m\3\ at each eligible monitoring site.
    (b) Three years of valid annual means are required to produce a 
valid annual PM2.5 NAAQS DV. A year meets data completeness 
requirements when quarterly data capture rates for all four quarters are 
at least 75 percent. However, years with at least 11 creditable samples 
in each quarter shall also be considered valid if the resulting annual 
mean or resulting annual PM2.5 NAAQS DV (rounded according to 
the conventions of section 4.3 of this appendix) is greater than the 
level of the applicable primary or secondary annual PM2.5 
NAAQS. Furthermore, where the explicit 75 percent data capture and/or 11 
sample minimum requirements are not met, the 3-year annual 
PM2.5 NAAQS DV shall still be considered valid if it passes 
at least one of the two data substitution tests stipulated below.
    (c) In the case of one, two, or three years that do not meet the 
completeness requirements of section 4.1(b) of this appendix and thus 
would normally not be useable for the calculation of a valid annual 
PM2.5 NAAQS DV, the annual PM2.5 NAAQS DV shall 
nevertheless be considered valid if one of the test

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conditions specified in sections 4.1(c)(i) and 4.1(c)(ii) of this 
appendix is met.
    (i) An annual PM2.5 NAAQS DV that is above the level of 
the NAAQS can be validated if it passes the minimum quarterly value data 
substitution test. This type of data substitution is permitted only if 
there are at least 30 days across the three quarters of the three years 
under consideration (e.g., collectively, quarter 1 of year 1, quarter 1 
of year 2 and quarter 1 of year 3) from which to select the quarter-
specific low value. Data substitution will be performed in all quarter 
periods that have less than 11 creditable samples.
    Procedure: Identify for each deficient quarter (i.e., those with 
less than 11 creditable samples) the lowest reported daily value for 
that quarter, looking across those three months of all three years under 
consideration. If after substituting the lowest reported daily value for 
a quarter for (11- cn) daily values in the matching deficient quarter(s) 
(i.e., to bring the creditable number for those quarters up to 11), the 
procedure yields a recalculated annual PM2.5 NAAQS test DV 
(TDVmin) that is greater than the level of the standard, then 
the annual PM2.5 NAAQS DV is deemed to have passed the 
diagnostic test and is valid, and the annual PM2.5 NAAQS is 
deemed to have been violated in that 3-year period.
    (ii) An annual PM2.5 NAAQS DV that is equal to or below 
the level of the NAAQS can be validated if it passes the maximum 
quarterly value data substitution test. This type of data substitution 
is permitted only if there is at least 50 percent data capture in each 
quarter that is deficient of 75 percent data capture in each of the 
three years under consideration. Data substitution will be performed in 
all quarter periods that have less than 75 percent data capture but at 
least 50 percent data capture. If any quarter has less than 50 percent 
data capture then this substitution test cannot be used.
    Procedure: Identify for each deficient quarter (i.e., those with 
less than 75 percent but at least 50 percent data capture) the highest 
reported daily value for that quarter, excluding state-flagged data 
affected by exceptional events which have been approved for exclusion by 
the Administrator, looking across those three quarters of all three 
years under consideration. If after substituting the highest reported 
daily PM2.5 value for a quarter for all missing daily data in 
the matching deficient quarter(s) (i.e., to make those quarters 100 
percent complete), the procedure yields a recalculated annual 
PM2.5 NAAQS test DV (TDVmax) that is less than or 
equal to the level of the standard, then the annual PM2.5 
NAAQS DV is deemed to have passed the diagnostic test and is valid, and 
the annual PM2.5 NAAQS is deemed to have been met in that 3-
year period.
    (d) An annual PM2.5 NAAQS DV based on data that do not 
meet the completeness criteria stated in 4(b) and also do not satisfy 
the test conditions specified in section 4(c), may also be considered 
valid with the approval of, or at the initiative of, the EPA 
Administrator, who may consider factors such as monitoring site 
closures/moves, monitoring diligence, the consistency and levels of the 
daily values that are available, and nearby concentrations in 
determining whether to use such data.
    (e) The equations for calculating the annual PM2.5 NAAQS 
DVs are given in section 4.4 of this appendix.

                    4.2 Twenty-four-hour PM2.5 NAAQS

    (a) The primary and secondary 24-hour PM2.5 NAAQS are met 
when the 24-hour PM2.5 NAAQS DV at each eligible monitoring 
site is less than or equal to 35 [micro]g/m\3\.
    (b) Three years of valid annual PM2.5 98th percentile 
mass concentrations are required to produce a valid 24-hour 
PM2.5 NAAQS DV. A year meets data completeness requirements 
when quarterly data capture rates for all four quarters are at least 75 
percent. However, years shall be considered valid, notwithstanding 
quarters with less than complete data (even quarters with less than 11 
creditable samples, but at least one creditable sample must be present 
for the year), if the resulting annual 98th percentile value or 
resulting 24-hour NAAQS DV (rounded according to the conventions of 
section 4.3 of this appendix) is greater than the level of the standard. 
Furthermore, where the explicit 75 percent quarterly data capture 
requirement is not met, the 24-hour PM2.5 NAAQS DV shall 
still be considered valid if it passes the maximum quarterly value data 
substitution test.
    (c) In the case of one, two, or three years that do not meet the 
completeness requirements of section 4.2(b) of this appendix and thus 
would normally not be useable for the calculation of a valid 24-hour 
PM2.5 NAAQS DV, the 24-hour PM2.5 NAAQS DV shall 
nevertheless be considered valid if the test conditions specified in 
section 4.2(c)(i) of this appendix are met.
    (i) A PM2.5 24-hour mass NAAQS DV that is equal to or 
below the level of the NAAQS can be validated if it passes the maximum 
quarterly value data substitution test. This type of data substitution 
is permitted only if there is at least 50 percent data capture in each 
quarter that is deficient of 75 percent data capture in each of the 
three years under consideration. Data substitution will be performed in 
all quarters that have less than 75 percent data capture but at least 50 
percent data capture. If any quarter has less than 50 percent data 
capture then this substitution test cannot be used.
    Procedure: Identify for each deficient quarter (i.e., those with 
less than 75 percent but

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at least 50 percent data capture) the highest reported daily 
PM2.5 value for that quarter, excluding state-flagged data 
affected by exceptional events which have been approved for exclusion by 
the Regional Administrator, looking across those three quarters of all 
three years under consideration. If, after substituting the highest 
reported daily maximum PM2.5 value for a quarter for all 
missing daily data in the matching deficient quarter(s) (i.e., to make 
those quarters 100 percent complete), the procedure yields a 
recalculated 3-year 24-hour NAAQS test DV (TDVmax) less than 
or equal to the level of the standard, then the 24-hour PM2.5 
NAAQS DV is deemed to have passed the diagnostic test and is valid, and 
the 24-hour PM2.5 NAAQS is deemed to have been met in that 3-
year period.
    (d) A 24-hour PM2.5 NAAQS DV based on data that do not 
meet the completeness criteria stated in section 4(b) of this appendix 
and also do not satisfy the test conditions specified in section 4(c) of 
this appendix, may also be considered valid with the approval of, or at 
the initiative of, the EPA Administrator, who may consider factors such 
as monitoring site closures/moves, monitoring diligence, the consistency 
and levels of the daily values that are available, and nearby 
concentrations in determining whether to use such data.
    (e) The procedures and equations for calculating the 24-hour 
PM2.5 NAAQS DVs are given in section 4.5 of this appendix.
    4.3 Rounding Conventions. For the purposes of comparing calculated 
PM2.5 NAAQS DVs to the applicable level of the standard, it 
is necessary to round the final results of the calculations described in 
sections 4.4 and 4.5 of this appendix. Results for all intermediate 
calculations shall not be rounded.
    (a) Annual PM2.5 NAAQS DVs shall be rounded to the 
nearest tenth of a [micro]g/m\3\ (decimals x.x5 and greater are rounded 
up to the next tenth, and any decimal lower than x.x5 is rounded down to 
the nearest tenth).
    (b) Twenty-four-hour PM2.5 NAAQS DVs shall be rounded to 
the nearest 1 [micro]g/m\3\ (decimals 0.5 and greater are rounded up to 
the nearest whole number, and any decimal lower than 0.5 is rounded down 
to the nearest whole number).

                4.4 Equations for the Annual PM2.5 NAAQS.

    (a) An annual mean value for PM2.5 is determined by first 
averaging the daily values of a calendar quarter using equation 1 of 
this appendix:
[GRAPHIC] [TIFF OMITTED] TR15JA13.005

Where:

Xq,y = the mean for quarter q of the year y;
nq = the number of daily values in the quarter; and
xi q,y = the i\th\ value in quarter q for year y.

    (b) Equation 2 of this appendix is then used to calculate the site 
annual mean:
[GRAPHIC] [TIFF OMITTED] TR20MR17.000

Where:

Xy = the annual mean concentration for year y (y = 1, 2, or 3);
nQ,y = the number of quarters Q in year y with at least one daily value; 
          and
Xq,y = the mean for quarter q of year y (result of equation 1).


[[Page 143]]


    (c) The annual PM2.5 NAAQS DV is calculated using 
equation 3 of this appendix:
[GRAPHIC] [TIFF OMITTED] TR15JA13.007

Where:

X = the annual PM2.5 NAAQS DV; and
Xy = the annual mean for year y (result of equation 2)

    (d) The annual PM2.5 NAAQS DV is rounded according to the 
conventions in section 4.3 of this appendix before comparisons with the 
levels of the primary and secondary annual PM2.5 NAAQS are 
made.

   4.5 Procedures and Equations for the 24-Hour PM2.5 NAAQS

    (a) When the data for a particular site and year meet the data 
completeness requirements in section 4.2 of this appendix, calculation 
of the 98th percentile is accomplished by the steps provided in this 
subsection. Table 1 of this appendix shall be used to identify annual 
98th percentile values.
    Identification of annual 98th percentile values using the Table 1 
procedure will be based on the creditable number of samples (as 
described below), rather than on the actual number of samples. Credit 
will not be granted for extra (non-creditable) samples. Extra samples, 
however, are candidates for selection as the annual 98th percentile. 
[The creditable number of samples will determine how deep to go into the 
data distribution, but all samples (creditable and extra) will be 
considered when making the percentile assignment.] The annual creditable 
number of samples is the sum of the four quarterly creditable number of 
samples.
    Procedure: Sort all the daily values from a particular site and year 
by descending value. (For example: (x[1], x[2], x[3], * * *, x[n]). In 
this case, x[1] is the largest number and x[n] is the smallest value.) 
The 98th percentile value is determined from this sorted series of daily 
values which is ordered from the highest to the lowest number. Using the 
left column of Table 1, determine the appropriate range for the annual 
creditable number of samples for year y (cny) (e.g., for 120 
creditable samples per year, the appropriate range would be 101 to 150). 
The corresponding ``n'' value in the right column identifies the rank of 
the annual 98th percentile value in the descending sorted list of site 
specific daily values for year y (e.g., for the range of 101 to 150, n 
would be 3). Thus, P0.98, y = the n\th\ largest value (e.g., 
for the range of 101 to 150, the 98th percentile value would be the 
third highest value in the sorted series of daily values.

                                 Table 1
------------------------------------------------------------------------
                                            The 98th percentile for year
                                              y (P0.98,y), is the n\th\
  Annual number of creditable samples for      maximum 24-hour average
               year y (cny)                  value for the year where n
                                                is the listed number
------------------------------------------------------------------------
1 to 50...................................                             1
51 to 100.................................                             2
101 to 150................................                             3
151 to 200................................                             4
201 to 250................................                             5
251 to 300................................                             6
301 to 350................................                             7
351 to 366................................                             8
------------------------------------------------------------------------

    (b) The 24-hour PM2.5 NAAQS DV is then calculated by 
averaging the annual 98th percentiles using equation 4 of this appendix: 
P0.98,y
[GRAPHIC] [TIFF OMITTED] TR15JA13.008


[[Page 144]]


Where:

    P0.98 = the 24-hour PM2.5 NAAQS DV; and
    P0.98, y = the annual 98th percentile for year y

    (c) The 24-hour PM2.5 NAAQS DV is rounded according to 
the conventions in section 4.3 of this appendix before a comparison with 
the level of the primary and secondary 24-hour NAAQS are made.

[78 FR 3277, Jan. 15, 2013, as amended at 82 FR 14327, Mar. 20, 2017]



 Sec. Appendix O to Part 50--Reference Method for the Determination of 
   Coarse Particulate Matter as PM10-2.5 in the Atmosphere

                    1.0 Applicability and Definition

    1.1 This method provides for the measurement of the mass 
concentration of coarse particulate matter (PM10-2.5) in 
ambient air over a 24-hour period. In conjunction with additional 
analysis, this method may be used to develop speciated data.
    1.2 For the purpose of this method, PM10-2.5 is defined 
as particulate matter having an aerodynamic diameter in the nominal 
range of 2.5 to 10 micrometers, inclusive.
    1.3 For this reference method, PM10-2.5 concentrations 
shall be measured as the arithmetic difference between separate but 
concurrent, collocated measurements of PM10 and 
PM2.5, where the PM10 measurements are obtained 
with a specially approved sampler, identified as a ``PM10c 
sampler,'' that meets more demanding performance requirements than 
conventional PM10 samplers described in appendix J of this 
part. Measurements obtained with a PM10c sampler are 
identified as ``PM10c measurements'' to distinguish them from 
conventional PM10 measurements obtained with conventional 
PM10 samplers. Thus, PM10-2.5 = PM10c - 
PM2.5.
    1.4 The PM10c and PM2.5 gravimetric 
measurement processes are considered to be nondestructive, and the 
PM10c and PM2.5 samples obtained in the 
PM10-2.5 measurement process can be subjected to subsequent 
physical or chemical analyses.
    1.5 Quality assessment procedures are provided in part 58, appendix 
A of this chapter. The quality assurance procedures and guidance 
provided in reference 1 in section 13 of this appendix, although written 
specifically for PM2.5, are generally applicable for 
PM10c, and, hence, PM10-2.5 measurements under 
this method, as well.
    1.6 A method based on specific model PM10c and 
PM2.5 samplers will be considered a reference method for 
purposes of part 58 of this chapter only if:
    (a) The PM10c and PM2.5 samplers and the 
associated operational procedures meet the requirements specified in 
this appendix and all applicable requirements in part 53 of this 
chapter, and
    (b) The method based on the specific samplers and associated 
operational procedures have been designated as a reference method in 
accordance with part 53 of this chapter.
    1.7 PM10-2.5 methods based on samplers that meet nearly 
all specifications set forth in this method but have one or more 
significant but minor deviations or modifications from those 
specifications may be designated as ``Class I'' equivalent methods for 
PM10-2.5 in accordance with part 53 of this chapter.
    1.8 PM2.5 measurements obtained incidental to the 
PM10-2.5 measurements by this method shall be considered to 
have been obtained with a reference method for PM2.5 in 
accordance with appendix L of this part.
    1.9 PM10c measurements obtained incidental to the 
PM10-2.5 measurements by this method shall be considered to 
have been obtained with a reference method for PM10 in 
accordance with appendix J of this part, provided that:
    (a) The PM10c measurements are adjusted to EPA reference 
conditions (25 [deg]C and 760 millimeters of mercury), and
    (b) Such PM10c measurements are appropriately identified 
to differentiate them from PM10 measurements obtained with 
other (conventional) methods for PM10 designated in 
accordance with part 53 of this chapter as reference or equivalent 
methods for PM10.

                              2.0 Principle

    2.1 Separate, collocated, electrically powered air samplers for 
PM10c and PM2.5 concurrently draw ambient air at 
identical, constant volumetric flow rates into specially shaped inlets 
and through one or more inertial particle size separators where the 
suspended particulate matter in the PM10 or PM2.5 
size range, as applicable, is separated for collection on a 
polytetrafluoroethylene (PTFE) filter over the specified sampling 
period. The air samplers and other aspects of this PM10-2.5 
reference method are specified either explicitly in this appendix or by 
reference to other applicable regulations or quality assurance guidance.
    2.2 Each PM10c and PM2.5 sample collection 
filter is weighed (after moisture and temperature conditioning) before 
and after sample collection to determine the net weight (mass) gain due 
to collected PM10c or PM2.5. The total volume of 
air sampled by each sampler is determined by the sampler from the 
measured flow rate at local ambient temperature and pressure and the 
sampling time. The mass concentrations of both PM10c and 
PM2.5 in the ambient air are computed as the total mass of 
collected particles in the PM10 or PM2.5 size 
range, as appropriate, divided by the total volume of air sampled by the 
respective samplers, and expressed in micrograms per cubic meter 
([micro]g/

[[Page 145]]

m\3\) at local temperature and pressure conditions. The mass 
concentration of PM10-2.5 is determined as the 
PM10c concentration value less the corresponding, 
concurrently measured PM2.5 concentration value.
    2.3 Most requirements for PM10-2.5 reference methods are 
similar or identical to the requirements for PM2.5 reference 
methods as set forth in appendix L to this part. To insure uniformity, 
applicable appendix L requirements are incorporated herein by reference 
in the sections where indicated rather than repeated in this appendix.

                     3.0 PM10	2.5 Measurement Range

    3.1 Lower concentration limit. The lower detection limit of the mass 
concentration measurement range is estimated to be approximately 3 
[micro]g/m\3\, based on the observed precision of PM2.5 
measurements in the national PM2.5 monitoring network, the 
probable similar level of precision for the matched PM10c 
measurements, and the additional variability arising from the 
differential nature of the measurement process. This value is provided 
merely as a guide to the significance of low PM10-2.5 
concentration measurements.
    3.2 Upper concentration limit. The upper limit of the mass 
concentration range is determined principally by the PM10c 
filter mass loading beyond which the sampler can no longer maintain the 
operating flow rate within specified limits due to increased pressure 
drop across the loaded filter. This upper limit cannot be specified 
precisely because it is a complex function of the ambient particle size 
distribution and type, humidity, the individual filter used, the 
capacity of the sampler flow rate control system, and perhaps other 
factors. All PM10c samplers are estimated to be capable of 
measuring 24-hour mass concentrations of at least 200 [micro]g/m\3\ 
while maintaining the operating flow rate within the specified limits. 
The upper limit for the PM10-2.5 measurement is likely to be 
somewhat lower because the PM10-2.5 concentration represents 
only a fraction of the PM10 concentration.
    3.3 Sample period. The required sample period for 
PM10-2.5 concentration measurements by this method shall be 
at least 1,380 minutes but not more than 1,500 minutes (23 to 25 hours), 
and the start times of the PM2.5 and PM10c samples 
are within 10 minutes and the stop times of the samples are also within 
10 minutes (see section 10.4 of this appendix).

                           4.0 Accuracy (bias)

    4.1 Because the size, density, and volatility of the particles 
making up ambient particulate matter vary over wide ranges and the mass 
concentration of particles varies with particle size, it is difficult to 
define the accuracy of PM10-2.5 measurements in an absolute 
sense. Furthermore, generation of credible PM10-2.5 
concentration standards at field monitoring sites and presenting or 
introducing such standards reliably to samplers or monitors to assess 
accuracy is still generally impractical. The accuracy of 
PM10-2.5 measurements is therefore defined in a relative 
sense as bias, referenced to measurements provided by other reference 
method samplers or based on flow rate verification audits or checks, or 
on other performance evaluation procedures.
    4.2 Measurement system bias for monitoring data is assessed 
according to the procedures and schedule set forth in part 58, appendix 
A of this chapter. The goal for the measurement uncertainty (as bias) 
for monitoring data is defined in part 58, appendix A of this chapter as 
an upper 95 percent confidence limit for the absolute bias of 15 
percent. Reference 1 in section 13 of this appendix provides additional 
information and guidance on flow rate accuracy audits and assessment of 
bias.

                              5.0 Precision

    5.1 Tests to establish initial measurement precision for each 
sampler of the reference method sampler pair are specified as a part of 
the requirements for designation as a reference method under part 53 of 
this chapter.
    5.2 Measurement system precision is assessed according to the 
procedures and schedule set forth in appendix A to part 58 of this 
chapter. The goal for acceptable measurement uncertainty, as precision, 
of monitoring data is defined in part 58, appendix A of this chapter as 
an upper 95 percent confidence limit for the coefficient of variation 
(CV) of 15 percent. Reference 1 in section 13 of this appendix provides 
additional information and guidance on this requirement.
    6.0 Filters for PM10c and PM2.5 Sample 
Collection. Sample collection filters for both PM10c and 
PM2.5 measurements shall be identical and as specified in 
section 6 of appendix L to this part.
    7.0 Sampler. The PM10-2.5 sampler shall consist of a 
PM10c sampler and a PM2.5 sampler, as follows:
    7.1 The PM2.5 sampler shall be as specified in section 7 
of appendix L to this part.
    7.2 The PM10c sampler shall be of like manufacturer, 
design, configuration, and fabrication to that of the PM2.5 
sampler and as specified in section 7 of appendix L to this part, except 
as follows:
    7.2.1 The particle size separator specified in section 7.3.4 of 
appendix L to this part shall be eliminated and replaced by a downtube 
extension fabricated as specified in Figure O-1 of this appendix.
    7.2.2 The sampler shall be identified as a PM10c sampler 
on its identification label required under Sec. 53.9(d) of this 
chapter.
    7.2.3 The average temperature and average barometric pressure 
measured by the

[[Page 146]]

sampler during the sample period, as described in Table L-1 of appendix 
L to this part, need not be reported to EPA's AQS data base, as required 
by section 7.4.19 and Table L-1 of appendix L to this part, provided 
such measurements for the sample period determined by the associated 
PM2.5 sampler are reported as required.
    7.3 In addition to the operation/instruction manual required by 
section 7.4.18 of appendix L to this part for each sampler, supplemental 
operational instructions shall be provided for the simultaneous 
operation of the samplers as a pair to collect concurrent 
PM10c and PM2.5 samples. The supplemental 
instructions shall cover any special procedures or guidance for 
installation and setup of the samplers for PM10-2.5 
measurements, such as synchronization of the samplers' clocks or timers, 
proper programming for collection of concurrent samples, and any other 
pertinent issues related to the simultaneous, coordinated operation of 
the two samplers.
    7.4 Capability for electrical interconnection of the samplers to 
simplify sample period programming and further ensure simultaneous 
operation is encouraged but not required. Any such capability for 
interconnection shall not supplant each sampler's capability to operate 
independently, as required by section 7 of appendix L of this part.

                           8.0 Filter Weighing

    8.1 Conditioning and weighing for both PM10c and 
PM2.5 sample filters shall be as specified in section 8 of 
appendix L to this part. See reference 1 of section 13 of this appendix 
for additional, more detailed guidance.
    8.2 Handling, conditioning, and weighing for both PM10c 
and PM2.5 sample filters shall be matched such that the 
corresponding PM10c and PM2.5 filters of each 
filter pair receive uniform treatment. The PM10c and 
PM2.5 sample filters should be weighed on the same balance, 
preferably in the same weighing session and by the same analyst.
    8.3 Due care shall be exercised to accurately maintain the paired 
relationship of each set of concurrently collected PM10c and 
PM2.5 sample filters and their net weight gain data and to 
avoid misidentification or reversal of the filter samples or weight 
data. See Reference 1 of section 13 of this appendix for additional 
guidance.
    9.0 Calibration. Calibration of the flow rate, temperature 
measurement, and pressure measurement systems for both the 
PM10c and PM2.5 samplers shall be as specified in 
section 9 of appendix L to this part.

                   10.0 PM10	2.5 Measurement Procedure

    10.1 The PM10c and PM2.5 samplers shall be 
installed at the monitoring site such that their ambient air inlets 
differ in vertical height by not more than 0.2 meter, if possible, but 
in any case not more than 1 meter, and the vertical axes of their inlets 
are separated by at least 1 meter but not more than 4 meters, 
horizontally.
    10.2 The measurement procedure for PM10c shall be as 
specified in section 10 of appendix L to this part, with 
``PM10c'' substituted for ``PM2.5'' wherever it 
occurs in that section.
    10.3 The measurement procedure for PM2.5 shall be as 
specified in section 10 of appendix L to this part.
    10.4 For the PM10-2.5 measurement, the PM10c 
and PM2.5 samplers shall be programmed to operate on the same 
schedule and such that the sample period start times are within 5 
minutes and the sample duration times are within 5 minutes.
    10.5 Retrieval, transport, and storage of each PM10c and 
PM2.5 sample pair following sample collection shall be 
matched to the extent practical such that both samples experience 
uniform conditions.
    11.0 Sampler Maintenance. Both PM10c and PM2.5 
samplers shall be maintained as described in section 11 of appendix L to 
this part.

                            12.0 Calculations

    12.1 Both concurrent PM10c and PM2.5 
measurements must be available, valid, and meet the conditions of 
section 10.4 of this appendix to determine the PM10-2.5 mass 
concentration.
    12.2 The PM10c mass concentration is calculated using 
equation 1 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.012

Where:

PM10c = mass concentration of PM10c, [micro]g/
          m\3\;
Wf, Wi = final and initial masses (weights), 
          respectively, of the filter used to collect the 
          PM10c particle sample, [micro]g;
Va = total air volume sampled by the PM10c sampler 
          in actual volume units measured at local conditions of 
          temperature and pressure, as provided by the sampler, m\3\.

    Note: Total sample time must be between 1,380 and 1,500 minutes (23 
and 25 hrs) for a fully valid PM10c sample; however, see also 
section 3.3 of this appendix.

    12.3 The PM2.5 mass concentration is calculated as 
specified in section 12 of appendix L to this part.
    12.4 The PM10-2.5 mass concentration, in [micro]g/m\3\, 
is calculated using Equation 2 of this section:

[[Page 147]]

[GRAPHIC] [TIFF OMITTED] TR17OC06.013

                             13.0 Reference

    1. Quality Assurance Guidance Document 2.12. Monitoring 
PM2.5 in Ambient Air Using Designated Reference or Class I 
Equivalent Methods. Draft, November 1998 (or later version or 
supplement, if available). Available at: www.epa.gov/ttn/amtic/
pgqa.html.

                              14.0 Figures

    Figure O-1 is included as part of this appendix O.

[[Page 148]]

[GRAPHIC] [TIFF OMITTED] TR17OC06.014


[[Page 149]]



[71 FR 61230, Oct. 17, 2006]



Sec. Appendix P to Part 50--Interpretation of the Primary and Secondary 
            National Ambient Air Quality Standards for Ozone

                               1. General

    (a) This appendix explains the data handling conventions and 
computations necessary for determining whether the national 8-hour 
primary and secondary ambient air quality standards for ozone 
(O3) specified in Sec. 50.15 are met at an ambient 
O3 air quality monitoring site. Ozone is measured in the 
ambient air by a reference method based on appendix D of this part, as 
applicable, and designated in accordance with part 53 of this chapter, 
or by an equivalent method designated in accordance with part 53 of this 
chapter. Data reporting, data handling, and computation procedures to be 
used in making comparisons between reported O3 concentrations 
and the levels of the O3 standards are specified in the 
following sections. Whether to exclude, retain, or make adjustments to 
the data affected by exceptional events, including stratospheric 
O3 intrusion and other natural events, is determined by the 
requirements under Sec. Sec. 50.1, 50.14 and 51.930.
    (b) The terms used in this appendix are defined as follows:
    8-hour average is the rolling average of eight hourly O3 
concentrations as explained in section 2 of this appendix.
    Annual fourth-highest daily maximum refers to the fourth highest 
value measured at a monitoring site during a particular year.
    Daily maximum 8-hour average concentration refers to the maximum 
calculated 8-hour average for a particular day as explained in section 2 
of this appendix.
    Design values are the metrics (i.e., statistics) that are compared 
to the NAAQS levels to determine compliance, calculated as shown in 
section 3 of this appendix.
    O3 monitoring season refers to the span of time within a 
calendar year when individual States are required to measure ambient 
O3 concentrations as listed in part 58 appendix D to this 
chapter.
    Year refers to calendar year.

    2. Primary and Secondary Ambient Air Quality Standards for Ozone

               2.1 Data Reporting and Handling Conventions

    Computing 8-hour averages. Hourly average concentrations shall be 
reported in parts per million (ppm) to the third decimal place, with 
additional digits to the right of the third decimal place truncated. 
Running 8-hour averages shall be computed from the hourly O3 
concentration data for each hour of the year and shall be stored in the 
first, or start, hour of the 8-hour period. An 8-hour average shall be 
considered valid if at least 75% of the hourly averages for the 8-hour 
period are available. In the event that only 6 or 7 hourly averages are 
available, the 8-hour average shall be computed on the basis of the 
hours available using 6 or 7 as the divisor. 8-hour periods with three 
or more missing hours shall be considered valid also, if, after 
substituting one-half the minimum detectable limit for the missing 
hourly concentrations, the 8-hour average concentration is greater than 
the level of the standard. The computed 8-hour average O3 
concentrations shall be reported to three decimal places (the digits to 
the right of the third decimal place are truncated, consistent with the 
data handling procedures for the reported data).
    Daily maximum 8-hour average concentrations. (a) There are 24 
possible running 8-hour average O3 concentrations for each 
calendar day during the O3 monitoring season. The daily 
maximum 8-hour concentration for a given calendar day is the highest of 
the 24 possible 8-hour average concentrations computed for that day. 
This process is repeated, yielding a daily maximum 8-hour average 
O3 concentration for each calendar day with ambient 
O3 monitoring data. Because the 8-hour averages are recorded 
in the start hour, the daily maximum 8-hour concentrations from two 
consecutive days may have some hourly concentrations in common. 
Generally, overlapping daily maximum 8-hour averages are not likely, 
except in those non-urban monitoring locations with less pronounced 
diurnal variation in hourly concentrations.
    (b) An O3 monitoring day shall be counted as a valid day 
if valid 8-hour averages are available for at least 75% of possible 
hours in the day (i.e., at least 18 of the 24 averages). In the event 
that less than 75% of the 8-hour averages are available, a day shall 
also be counted as a valid day if the daily maximum 8-hour average 
concentration for that day is greater than the level of the standard.

      2.2 Primary and Secondary Standard-related Summary Statistic

    The standard-related summary statistic is the annual fourth-highest 
daily maximum 8-hour O3 concentration, expressed in parts per 
million, averaged over three years. The 3-year average shall be computed 
using the three most recent, consecutive calendar years of monitoring 
data meeting the data completeness requirements described in this 
appendix. The computed 3-year average of the annual fourth-highest daily 
maximum 8-hour average O3 concentrations shall be reported to 
three decimal places (the digits to the right of the third decimal place 
are truncated, consistent with the data handling procedures for the 
reported data).

[[Page 150]]

     2.3 Comparisons with the Primary and Secondary Ozone Standards

    (a) The primary and secondary O3 ambient air quality 
standards are met at an ambient air quality monitoring site when the 3-
year average of the annual fourth-highest daily maximum 8-hour average 
O3 concentration is less than or equal to 0.075 ppm.
    (b) This comparison shall be based on three consecutive, complete 
calendar years of air quality monitoring data. This requirement is met 
for the 3-year period at a monitoring site if daily maximum 8-hour 
average concentrations are available for at least 90% of the days within 
the O3 monitoring season, on average, for the 3-year period, 
with a minimum data completeness requirement in any one year of at least 
75% of the days within the O3 monitoring season. When 
computing whether the minimum data completeness requirements have been 
met, meteorological or ambient data may be sufficient to demonstrate 
that meteorological conditions on missing days were not conducive to 
concentrations above the level of the standard. Missing days assumed 
less then the level of the standard are counted for the purpose of 
meeting the data completeness requirement, subject to the approval of 
the appropriate Regional Administrator.
    (c) Years with concentrations greater than the level of the standard 
shall be included even if they have less than complete data. Thus, in 
computing the 3-year average fourth maximum concentration, calendar 
years with less than 75% data completeness shall be included in the 
computation if the 3-year average fourth-highest 8-hour concentration is 
greater than the level of the standard.
    (d) Comparisons with the primary and secondary O3 
standards are demonstrated by examples 1 and 2 in paragraphs (d)(1) and 
(d)(2) respectively as follows:

                                   Example 1--Ambient Monitoring Site Attaining the Primary and Secondary O3 Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Percent valid
                                                           days (within     1st Highest     2nd Highest     3rd Highest     4th Highest     5th Highest
                          Year                             the required    daily max 8-    daily max 8-    daily max 8-    daily max 8-    daily max 8-
                                                            monitoring      hour Conc.      hour Conc.      hour Conc.      hour Conc.      hour Conc.
                                                              season)          (ppm)           (ppm)           (ppm)           (ppm)           (ppm)
--------------------------------------------------------------------------------------------------------------------------------------------------------
2004....................................................             100           0.092           0.090           0.085           0.079           0.078
2005....................................................              96           0.084           0.083           0.075           0.072           0.070
2006....................................................              98           0.080           0.079           0.077           0.076           0.060
                                                         -----------------------------------------------------------------------------------------------
    Average.............................................              98  ..............  ..............  ..............           0.075  ..............
--------------------------------------------------------------------------------------------------------------------------------------------------------

    (1) As shown in Example 1, this monitoring site meets the primary 
and secondary O3 standards because the 3-year average of the 
annual fourth-highest daily maximum 8-hour average O3 
concentrations (i.e., 0.075666 * * * ppm, truncated to 0.075 ppm) is 
less than or equal to 0.075 ppm. The data completeness requirement is 
also met because the average percent of days within the required 
monitoring season with valid ambient monitoring data is greater than 
90%, and no single year has less than 75% data completeness. In Example 
1, the individual 8-hour averages used to determine the annual fourth 
maximum have also been truncated to the third decimal place.

                                Example 2--Ambient Monitoring Site Failing to Meet the Primary and Secondary O3 Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Percent valid
                                                           days (within     1st Highest     2nd Highest     3rd Highest     4th Highest     5th Highest
                          Year                             the required    daily max 8-    daily max 8-    daily max 8-    daily max 8-    daily max 8-
                                                            monitoring      hour Conc.      hour Conc.      hour Conc.      hour Conc.      hour Conc.
                                                              season)          (ppm)           (ppm)           (ppm)           (ppm)           (ppm)
--------------------------------------------------------------------------------------------------------------------------------------------------------
2004....................................................              96           0.105           0.103           0.103           0.103           0.102
2005....................................................              74           0.104           0.103           0.092           0.091           0.088
2006....................................................              98           0.103           0.101           0.101           0.095           0.094
                                                         -----------------------------------------------------------------------------------------------
    Average.............................................              89  ..............  ..............  ..............           0.096  ..............
--------------------------------------------------------------------------------------------------------------------------------------------------------

    As shown in Example 2, the primary and secondary O3 
standards are not met for this monitoring site because the 3-year 
average of the fourth-highest daily maximum 8-hour average O3 
concentrations (i.e., 0.096333 * * * ppm, truncated to 0.096 ppm) is 
greater than 0.075 ppm, even though the data capture is less than 75% 
and the average data capture for the 3 years is less than 90% within the 
required monitoring season. In Example 2, the individual 8-hour averages 
used to determine

[[Page 151]]

the annual fourth maximum have also been truncated to the third decimal 
place.

3. Design Values for Primary and Secondary Ambient Air Quality Standards 
                                for Ozone

    The air quality design value at a monitoring site is defined as that 
concentration that when reduced to the level of the standard ensures 
that the site meets the standard. For a concentration-based standard, 
the air quality design value is simply the standard-related test 
statistic. Thus, for the primary and secondary standards, the 3-year 
average annual fourth-highest daily maximum 8-hour average O3 
concentration is also the air quality design value for the site.

[73 FR 16511, Mar. 27, 2008]



 Sec. Appendix Q to Part 50--Reference Method for the Determination of 
Lead in Particulate Matter as PM10 Collected From Ambient Air

    This Federal Reference Method (FRM) draws heavily from the specific 
analytical protocols used by the U.S. EPA.
    1. Applicability and Principle
    1.1 This method provides for the measurement of the lead (Pb) 
concentration in particulate matter that is 10 micrometers or less 
(PM10) in ambient air. PM10 is collected on an 
acceptable (see section 6.1.2) 46.2 mm diameter polytetrafluoroethylene 
(PTFE) filter for 24 hours using active sampling at local conditions 
with a low-volume air sampler. The low-volume sampler has an average 
flow rate of 16.7 liters per minute (Lpm) and total sampled volume of 24 
cubic meters (m\3\) of air. The analysis of Pb in PM10 is 
performed on each individual 24-hour sample. Gravimetric mass analysis 
of PM10c filters is not required for Pb analysis. For the 
purpose of this method, PM10 is defined as particulate matter 
having an aerodynamic diameter in the nominal range of 10 micrometers 
(10 [micro]m) or less.
    1.2 For this reference method, PM10 shall be collected 
with the PM10c federal reference method (FRM) sampler as 
described in appendix O to Part 50 using the same sample period, 
measurement procedures, and requirements specified in appendix L of Part 
50. The PM10c sampler is also being used for measurement of 
PM10-2.5 mass by difference and as such, the PM10c 
sampler must also meet all of the performance requirements specified for 
PM2.5 in appendix L. The concentration of Pb in the 
atmosphere is determined in the total volume of air sampled and 
expressed in micrograms per cubic meter ([micro]g/m\3\) at local 
temperature and pressure conditions.
    1.3 The FRM will serve as the basis for approving Federal Equivalent 
Methods (FEMs) as specified in 40 CFR Part 53 (Reference and Equivalent 
Methods). This FRM specifically applies to the analysis of Pb in 
PM10 filters collected with the PM10c sampler. If 
these filters are analyzed for elements other than Pb, then refer to the 
guidance provided in the EPA Inorganic Compendium Method IO-3.3 
(Reference 1 of section 8) for multi-element analysis.
    1.4 The PM10c air sampler draws ambient air at a constant 
volumetric flow rate into a specially shaped inlet and through an 
inertial particle size separator, where the suspended particulate matter 
in the PM10 size range is separated for collection on a PTFE 
filter over the specified sampling period. The Pb content of the 
PM10 sample is analyzed by energy-dispersive X-ray 
fluorescence spectrometry (EDXRF). Energy-dispersive X-ray fluorescence 
spectrometry provides a means for identification of an element by 
measurement of its characteristic X-ray emission energy. The method 
allows for quantification of the element by measuring the intensity of 
X-rays emitted at the characteristic photon energy and then relating 
this intensity to the elemental concentration. The number or intensity 
of X-rays produced at a given energy provides a measure of the amount of 
the element present by comparisons with calibration standards. The X-
rays are detected and the spectral signals are acquired and processed 
with a personal computer. EDXRF is commonly used as a non-destructive 
method for quantifying trace elements in PM. A detailed explanation of 
quantitative X-ray spectrometry is described in references 2, 3 and 4.
    1.5 Quality assurance (QA) procedures for the collection of 
monitoring data are contained in Part 58, appendix A.
    2. PM10Pb Measurement Range and Detection Limit. The values given 
below in section 2.1 and 2.2 are typical of the method capabilities. 
Absolute values will vary for individual situations depending on the 
instrument, detector age, and operating conditions used. Data are 
typically reported in ng/m\3\ for ambient air samples; however, for this 
reference method, data will be reported in [micro]g/m\3\ at local 
temperature and pressure conditions.
    2.1 EDXRF Pb Measurement Range. The typical ambient air measurement 
range is 0.001 to 30 [micro]g Pb/m\3\, assuming an upper range 
calibration standard of about 60 [micro]g Pb per square centimeter 
(cm\2\), a filter deposit area of 11.86 cm\2\, and an air volume of 24 
m\3\. The top range of the EDXRF instrument is much greater than what is 
stated here. The top measurement range of quantification is defined by 
the level of the high concentration calibration standard used and can be 
increased to expand the measurement range as needed.
    2.2 Detection Limit (DL). A typical estimate of the one-sigma 
detection limit (DL) is about 2 ng Pb/cm\2\ or 0.001 [micro]g Pb/m\3\, 
assuming a filter size of 46.2 mm (filter deposit

[[Page 152]]

area of 11.86 cm\2\) and a sample air volume of 24 m\3\. The DL is an 
estimate of the lowest amount of Pb that can be reliably distinguished 
from a blank filter. The one-sigma detection limit for Pb is calculated 
as the average overall uncertainty or propagated error for Pb, 
determined from measurements on a series of blank filters from the 
filter lot(s) in use. Detection limits must be determined for each 
filter lot in use. If a new filter lot is used, then a new DL must be 
determined. The sources of random error which are considered are 
calibration uncertainty; system stability; peak and background counting 
statistics; uncertainty in attenuation corrections; and uncertainty in 
peak overlap corrections, but the dominating source by far is peak and 
background counting statistics. At a minimum, laboratories are to 
determine annual estimates of the DL using the guidance provided in 
Reference 5.
    3. Factors Affecting Bias and Precision of Lead Determination by 
EDXRF
    3.1 Filter Deposit. X-ray spectra are subject to distortion if 
unusually heavy deposits are analyzed. This is the result of internal 
absorption of both primary and secondary X-rays within the sample; 
however, this is not an issue for Pb due to the energetic X-rays used to 
fluoresce Pb and the energetic characteristic X-rays emitted by Pb. The 
optimum mass filter loading for multi-elemental EDXRF analyis is about 
100 [micro]g/cm\2\ or 1.2 mg/filter for a 46.2-mm filter. Too little 
deposit material can also be problematic due to low counting statistics 
and signal noise. The particle mass deposit should minimally be 15 
[micro]g/cm\2\. The maximum PM10 filter loading or upper 
concentration limit of mass expected to be collected by the 
PM10c sampler is 200 [micro]g/m\3\ (Appendix O to Part 50, 
Section 3.2). This equates to a mass loading of about 400 [micro]g/cm\2\ 
and is the maximum expected loading for PM10c filters. This 
maximum loading is acceptable for the analysis of Pb and other high-Z 
elements with very energetic characteristic X-rays. A properly collected 
sample will have a uniform deposit over the entire collection area. 
Samples with physical deformities (including a visually non-uniform 
deposit area) should not be quantitatively analyzed. Tests on the 
uniformity of particle deposition on PM10C filters showed 
that the non-uniformity of the filter deposit represents a small 
fraction of the overall uncertainty in ambient Pb concentration 
measurement. The analysis beam of the XRF analyzer does not cover the 
entire filter collection area. The minimum allowable beam size is 10 mm.
    3.2 Spectral Interferences and Spectral Overlap. Spectral 
interference occurs when the entirety of the analyte spectral lines of 
two species are nearly 100% overlapped. The presence of arsenic (As) is 
a problematic interference for EDXRF systems which use the Pb L[alpha] 
line exclusively to quantify the Pb concentration. This is because the 
Pb L[alpha] line and the As K[alpha] lines severely overlap. The use of 
multiple Pb lines, including the L[beta] and/or the L[gamma] lines for 
quantification must be used to reduce the uncertainty in the Pb 
determination in the presence of As. There can be instances when lines 
partially overlap the Pb spectral lines, but with the energy resolution 
of most detectors these overlaps are typically de-convoluted using 
standard spectral de-convolution software provided by the instrument 
vendor. An EDXRF protocol for Pb must define which Pb lines are used for 
quantification and where spectral overlaps occur. A de-convolution 
protocol must be used to separate all the lines which overlap with Pb.
    3.3 Particle Size Effects and Attenuation Correction Factors. X-ray 
attenuation is dependent on the X-ray energy, mass sample loading, 
composition, and particle size. In some cases, the excitation and 
fluorescent X-rays are attenuated as they pass through the sample. In 
order to relate the measured intensity of the X-rays to the thin-film 
calibration standards used, the magnitude of any attenuation present 
must be corrected for. See references 6, 7, and 8 for more discussion on 
this issue. Essentially no attenuation corrections are necessary for Pb 
in PM10: Both the incoming excitation X-rays used for 
analyzing lead and the fluoresced Pb X-rays are sufficiently energetic 
that for particles in this size range and for normal filter loadings, 
the Pb X-ray yield is not significantly impacted by attenuation.
    4. Precision
    4.1 Measurement system precision is assessed according to the 
procedures set forth in appendix A to part 58. Measurement method 
precision is assessed from collocated sampling and analysis. The goal 
for acceptable measurement uncertainty, as precision, is defined as an 
upper 90 percent confidence limit for the coefficient of variation (CV) 
of 20 percent.
    5. Bias
    5.1 Measurement system bias for monitoring data is assessed 
according to the procedures set forth in appendix A of part 58. The bias 
is assessed through an audit using spiked filters. The goal for 
measurement bias is defined as an upper 95 percent confidence limit for 
the absolute bias of 15 percent.
    6. Measurement of PTFE Filters by EDXRF
    6.1 Sampling
    6.1.1 Low-Volume PM10cSampler. The low-volume PM10c 
sampler shall be used for PM10 sample collection and operated 
in accordance with the performance specifications described in part 50, 
appendix L.
    6.1.2 PTFE Filters and Filter Acceptance Testing. The PTFE filters 
used for PM10c sample collection shall meet the 
specifications provided in part 50, appendix L. The following 
requirements are similar to those

[[Page 153]]

currently specified for the acceptance of PM2.5 filters that 
are tested for trace elements by EDXRF. For large filter lots (greater 
than 500 filters) randomly select 20 filters from a given lot. For small 
lots (less than 500 filters) a lesser number of filters may be taken. 
Analyze each blank filter separately and calculate the average lead 
concentration in ng/cm\2\. Ninety percent, or 18 of the 20 filters, must 
have an average lead concentration that is less than 4.8 ng Pb/cm\2\.
    6.1.2.1 Filter Blanks. Field blank filters shall be collected along 
with routine samples. Field blank filters will be collected that are 
transported to the sampling site and placed in the sampler for the 
duration of sampling without sampling. Laboratory blank filters from 
each filter lot used shall be analyzed with each batch of routine sample 
filters analyzed. Laboratory blank filters are used in background 
subtraction as discussed below in Section 6.2.4.
    6.2 Analysis. The four main categories of random and systematic 
error encountered in X-ray fluorescence analysis include errors from 
sample collection, the X-ray source, the counting process, and inter-
element effects. These errors are addressed through the calibration 
process and mathematical corrections in the instrument software. 
Spectral processing methods are well established and most commercial 
analyzers have software that can implement the most common approaches 
(references 9-11) to background subtraction, peak overlap correction, 
counting and deadtime corrections.
    6.2.1 EDXRF Analysis Instrument. An energy-dispersive XRF system is 
used. Energy-dispersive XRF systems are available from a number of 
commercial vendors. Examples include Thermo (www.thermo.com), Spectro 
(http://www.spectro.com), Xenemetrix (http://www.xenemetrix.com) and 
PANalytical (http://www.panalytical.com). \1\ The analysis is performed 
at room temperature in either vacuum or in a helium atmosphere. The 
specific details of the corrections and calibration algorithms are 
typically included in commercial analytical instrument software routines 
for automated spectral acquisition and processing and vary by 
manufacturer. It is important for the analyst to understand the 
correction procedures and algorithms of the particular system used, to 
ensure that the necessary corrections are applied.
---------------------------------------------------------------------------

    \1\ These are examples of available systems and is not an all 
inclusive list. The mention of commercial products does not imply 
endorsement by the U.S. Environmental Protection Agency.
---------------------------------------------------------------------------

    6.2.2 Thin film standards. Thin film standards are used for 
calibration because they most closely resemble the layer of particles on 
a filter. Thin films standards are typically deposited on Nuclepore 
substrates. The preparation of thin film standards is discussed in 
reference 8, and 10. The NIST SRM 2783 (Air Particulate on Filter Media) 
is currently available on polycarbonate filters and contains a certified 
concentration for Pb. Thin film standards at 15 and 50 [micro]g/cm\2\ 
are commercially available from MicroMatter Inc. (Arlington, WA).
    6.2.3 Filter Preparation. Filters used for sample collection are 
46.2-mm PTFE filters with a pore size of 2 microns and filter deposit 
area 11.86 cm\2\. Cold storage is not a requirement for filters analyzed 
for Pb; however, if filters scheduled for XRF analysis were stored cold, 
they must be allowed to reach room temperature prior to analysis. All 
filter samples received for analysis are checked for any holes, tears, 
or a non-uniform deposit which would prevent quantitative analysis. 
Samples with physical deformities are not quantitatively analyzable. The 
filters are carefully removed with tweezers from the Petri dish and 
securely placed into the instrument-specific sampler holder for 
analysis. Care must be taken to protect filters from contamination prior 
to analysis. Filters must be kept covered when not being analyzed. No 
other preparation of filter samples is required.
    6.2.4 Calibration. In general, calibration determines each element's 
sensitivity, i.e., its response in x-ray counts/sec to each [micro]g/
cm\2\ of a standard and an interference coefficient for each element 
that causes interference with another one (See section 3.2 above). The 
sensitivity can be determined by a linear plot of count rate versus 
concentration ([micro]g/cm\2\) in which the slope is the instrument's 
sensitivity for that element. A more precise way, which requires fewer 
standards, is to fit sensitivity versus atomic number. Calibration is a 
complex task in the operation of an XRF system. Two major functions 
accomplished by calibration are the production of reference spectra 
which are used for fitting and the determination of the elemental 
sensitivities. Included in the reference spectra (referred to as 
``shapes'') are background-subtracted peak shapes of the elements to be 
analyzed (as well as interfering elements) and spectral backgrounds. 
Pure element thin film standards are used for the element peak shapes 
and clean filter blanks from the same lot as routine filter samples are 
used for the background. The analysis of Pb in PM filter deposits is 
based on the assumption that the thickness of the deposit is small with 
respect to the characteristic Pb X-ray transmission thickness. 
Therefore, the concentration of Pb in a sample is determined by first 
calibrating the spectrometer with thin film standards to determine the 
sensitivity factor for Pb and then analyzing the unknown samples under 
identical excitation conditions as used to determine the calibration. 
Calibration shall be

[[Page 154]]

performed annually or when significant repairs or changes occur (e.g., a 
change in fluorescers, X-ray tubes, or detector). Calibration 
establishes the elemental sensitivity factors and the magnitude of 
interference or overlap coefficients. See reference 7 for more detailed 
discussion of calibration and analysis of shapes standards for 
background correction, coarse particle absorption corrections, and 
spectral overlap.
    6.2.4.1 Spectral Peak Fitting. The EPA uses a library of pure 
element peak shapes (shape standards) to extract the elemental 
background-free peak areas from an unknown spectrum. It is also possible 
to fit spectra using peak stripping or analytically defined functions 
such as modified Gaussian functions. The EPA shape standards are 
generated from pure, mono-elemental thin film standards. The shape 
standards are acquired for sufficiently long times to provide a large 
number of counts in the peaks of interest. It is not necessary for the 
concentration of the standard to be known. A slight contaminant in the 
region of interest in a shape standard can have a significant and 
serious effect on the ability of the least squares fitting algorithm to 
fit the shapes to the unknown spectrum. It is these elemental peak 
shapes that are fitted to the peaks in an unknown sample during spectral 
processing by the analyzer. In addition to this library of elemental 
shapes there is also a background shape spectrum for the filter type 
used as discussed below in section 6.2.4.2 of this section.
    6.2.4.2 Background Measurement and Correction. A background spectrum 
generated by the filter itself must be subtracted from the X-ray 
spectrum prior to extracting peak areas. Background spectra must be 
obtained for each filter lot used for sample collection. The background 
shape standards which are used for background fitting are created at the 
time of calibration. If a new lot of filters is used, new background 
spectra must be obtained. A minimum of 20 clean blank filters from each 
filter lot are kept in a sealed container and are used exclusively for 
background measurement and correction. The spectra acquired on 
individual blank filters are added together to produce a single spectrum 
for each of the secondary targets or fluorescers used in the analysis of 
lead. Individual blank filter spectra which show atypical contamination 
are excluded from the summed spectra. The summed spectra are fitted to 
the appropriate background during spectral processing. Background 
correction is automatically included during spectral processing of each 
sample.
    7. Calculation.
    7.1 PM10 Pb concentrations. The PM10 Pb concentration in 
the atmosphere ([micro]g/m\3\) is calculated using the following 
equation:
[GRAPHIC] [TIFF OMITTED] TR12NO08.000

Where,

MPb is the mass per unit volume for lead in [micro]g/m\3\;
CPb is the mass per unit area for lead in [micro]g/cm\2\ as measured by 
          XRF;
A is the filter deposit area in cm\2\;
VLC is the total volume of air sampled by the PM10c sampler 
          in actual volume units measured at local conditions of 
          temperature and pressure, as provided by the sampler in m\3\.

    7.2 PM10 Pb Uncertainty Calculations.
    The principal contributors to total uncertainty of XRF values 
include: field sampling; filter deposit area; XRF calibration; 
attenuation or loss of the x-ray signals due to the other components of 
the particulate sample; and determination of the Pb X-ray emission peak 
area by curve fitting. See reference 12 for a detailed discussion of how 
uncertainties are similarly calculated for the PM2.5 Chemical 
Speciation program.
    The model for calculating total uncertainty is:

[delta]tot = ([delta]f2 + [delta]a2 + [delta]c2 + [delta]v2) 1/2

Where,

[delta]f = fitting uncertainty (XRF-specific, from 2 to 100 + 
          %)
[delta]a = attenuation uncertainty (XRF-specific, 
          insignificant for Pb)
[delta]c = calibration uncertainty (combined lab uncertainty, 
          assumed as 5%)
[delta]v = volume/deposition size uncertainty (combined field 
          uncertainty, assumed as 5%)

    8. References
    1. Inorganic Compendium Method IO-3.3; Determination of Metals in 
Ambient Particulate Matter Using X-Ray Fluorescence (XRF) Spectroscopy; 
U.S. Environmental Protection Agency, Cincinnati, OH 45268. EPA/625/R-
96/010a. June 1999.
    2. Jenkins, R., Gould, R.W., and Gedcke, D. Quantitative X-ray 
Spectrometry: Second Edition. Marcel Dekker, Inc., New York, NY. 1995.
    3. Jenkins, R. X-Ray Fluorescence Spectrometry: Second Edition in 
Chemical Analysis, a Series of Monographs on Analytical Chemistry and 
Its Applications, Volume 152. Editor J.D.Winefordner; John Wiley & Sons, 
Inc., New York, NY. 1999.
    4. Dzubay, T.G. X-ray Fluorescence Analysis of Environmental 
Samples, Ann Arbor Science Publishers Inc., 1977.
    5. Code of Federal Regulations (CFR) 40, Part 136, Appendix B; 
Definition and Procedure for the Determination of the Method Detection 
Limit--Revision 1.1.
    6. Drane, E.A, Rickel, D.G., and Courtney, W.J., ``Computer Code for 
Analysis X-Ray

[[Page 155]]

Fluorescence Spectra of Airborne Particulate Matter,'' in Advances in X-
Ray Analysis, J.R. Rhodes, Ed., Plenum Publishing Corporation, New York, 
NY, p. 23 (1980).
    7. Analysis of Energy-Dispersive X-ray Spectra of Ambient Aerosols 
with Shapes Optimization, Guidance Document; TR-WDE-06-02; prepared 
under contract EP-D-05-065 for the U.S. Environmental Protection Agency, 
National Exposure Research Laboratory. March 2006.
    8. Billiet, J., Dams, R., and Hoste, J. (1980) Multielement Thin 
Film Standards for XRF Analysis, X-Ray Spectrometry, 9(4): 206-211.
    9. Bonner, N.A.; Bazan, F.; and Camp, D.C. (1973). Elemental 
analysis of air filter samples using x-ray fluorescence. Report No. 
UCRL-51388. Prepared for U.S. Atomic Energy Commission, by Univ. of 
Calif., Lawrence Livermore Laboratory, Livermore, CA.
    10. Dzubay, T.G.; Lamothe, P.J.; and Yoshuda, H. (1977). Polymer 
films as calibration standards for X-ray fluorescence analysis. Adv. X-
Ray Anal., 20:411.
    11. Giauque, R.D.; Garrett, R.B.; and Goda, L.Y. (1977). Calibration 
of energy-dispersive X-ray spectrometers for analysis of thin 
environmental samples. In X-Ray Fluorescence Analysis of Environmental 
Samples, T.G. Dzubay, Ed., Ann Arbor Science Publishers, Ann Arbor, MI, 
pp. 153-181.
    12. Harmonization of Interlaboratory X-ray Fluorescence Measurement 
Uncertainties, Detailed Discussion Paper; August 4, 2006; prepared for 
the Office of Air Quality Planning and Standards under EPA contract 68-
D-03-038. http://www.epa.gov/ttn/amtic/files/ambient/pm25/spec/
xrfdet.pdf.

[73 FR 67052, Nov. 12, 2008]



 Sec. Appendix R to Part 50--Interpretation of the National Ambient Air 
                       Quality Standards for Lead

                               1. General.

    (a) This appendix explains the data handling conventions and 
computations necessary for determining when the primary and secondary 
national ambient air quality standards (NAAQS) for lead (Pb) specified 
in Sec. 50.16 are met. The NAAQS indicator for Pb is defined as: lead 
and its compounds, measured as elemental lead in total suspended 
particulate (Pb-TSP), sampled and analyzed by a Federal reference method 
(FRM) based on appendix G to this part or by a Federal equivalent method 
(FEM) designated in accordance with part 53 of this chapter. Although 
Pb-TSP is the lead NAAQS indicator, surrogate Pb-TSP concentrations 
shall also be used for NAAQS comparisons; specifically, valid surrogate 
Pb-TSP data are concentration data for lead and its compounds, measured 
as elemental lead, in particles with an aerodynamic size of 10 microns 
or less (Pb-PM10), sampled and analyzed by an FRM based on 
appendix Q to this part or by an FEM designated in accordance with part 
53 of this chapter. Surrogate Pb-TSP data (i.e., Pb-PM10 
data), however, can only be used to show that the Pb NAAQS were violated 
(i.e., not met); they can not be used to demonstrate that the Pb NAAQS 
were met. Pb-PM10 data used as surrogate Pb-TSP data shall be 
processed at face value; that is, without any transformation or scaling. 
Data handling and computation procedures to be used in making 
comparisons between reported and/or surrogate Pb-TSP concentrations and 
the level of the Pb NAAQS are specified in the following sections.
    (b) Whether to exclude, retain, or make adjustments to the data 
affected by exceptional events, including natural events, is determined 
by the requirements and process deadlines specified in Sec. Sec. 50.1, 
50.14, and 51.930 of this chapter.
    (c) The terms used in this appendix are defined as follows:
    Annual monitoring network plan refers to the plan required by 
section 58.10 of this chapter.
    Creditable samples are samples that are given credit for data 
completeness. They include valid samples collected on required sampling 
days and valid ``make-up'' samples taken for missed or invalidated 
samples on required sampling days.
    Daily values for Pb refer to the 24-hour mean concentrations of Pb 
(Pb-TSP or Pb-PM10), measured from midnight to midnight 
(local standard time), that are used in NAAQS computations.
    Design value is the site-level metric (i.e., statistic) that is 
compared to the NAAQS level to determine compliance; the design value 
for the Pb NAAQS is selected according to the procedures in this 
appendix from among the valid three-month Pb-TSP and surrogate Pb-TSP 
(Pb-PM10) arithmetic mean concentration for the 38-month 
period consisting of the most recent 3-year calendar period plus two 
previous months (i.e., 36 3-month periods) using the last month of each 
3-month period as the period of report.
    Extra samples are non-creditable samples. They are daily values that 
do not occur on scheduled sampling days and that can not be used as 
``make-up samples'' for missed or invalidated scheduled samples. Extra 
samples are used in mean calculations. For purposes of determining 
whether a sample must be treated as a make-up sample or an extra sample, 
Pb-TSP and Pb-PM10 data collected before January 1, 2009 will 
be treated with an assumed scheduled sampling frequency of every sixth 
day.
    Make-up samples are samples taken to replace missed or invalidated 
required scheduled samples. Make-ups can be made by either the primary 
or collocated (same size fraction) instruments; to be considered a

[[Page 156]]

valid make-up, the sampling must be conducted with equipment and 
procedures that meet the requirements for scheduled sampling. Make-up 
samples are either taken before the next required sampling day or 
exactly one week after the missed (or voided) sampling day. Make-up 
samples can not span years; that is, if a scheduled sample for December 
is missed (or voided), it can not be made up in January. Make-up 
samples, however, may span months, for example a missed sample on 
January 31 may be made up on February 1, 2, 3, 4, 5, or 7 (with an 
assumed sampling frequency of every sixth day). Section 3(e) explains 
how such month-spanning make-up samples are to be treated for purposes 
of data completeness and mean calculations. Only two make-up samples are 
permitted each calendar month; these are counted according to the month 
in which the miss and not the makeup occurred. For purposes of 
determining whether a sample must be treated as a make-up sample or an 
extra sample, Pb-TSP and Pb-PM10 data collected before 
January 1, 2009 will be treated with an assumed scheduled sampling 
frequency of every sixth day.
    Monthly mean refers to an arithmetic mean, calculated as specified 
in section 6(a) of this appendix. Monthly means are computed at each 
monitoring site separately for Pb-TSP and Pb-PM10 (i.e., by 
site-parameter-year-month).
    Parameter refers either to Pb-TSP or to Pb-PM10.
    Pollutant Occurrence Code (POC) refers to a numerical code (1, 2, 3, 
etc.) used to distinguish the data from two or more monitors for the 
same parameter at a single monitoring site.
    Scheduled sampling day means a day on which sampling is scheduled 
based on the required sampling frequency for the monitoring site, as 
provided in section 58.12 of this chapter.
    Three-month means are arithmetic averages of three consecutive 
monthly means. Three-month means are computed on a rolling, overlapping 
basis. Each distinct monthly mean will be included in three different 3-
month means; for example, in a given year, a November mean would be 
included in: (1) The September-October-November 3-month mean, (2) the 
October-November-December 3-month mean, and (3) the November-December-
January(of the following year) 3-month mean. Three-month means are 
computed separately for each parameter per section 6(a) (and are 
referred to as 3-month parameter means) and are validated according to 
the criteria specified in section 4(c). The parameter-specific 3-month 
means are then prioritized according to section 2(a) to determine a 
single 3-month site mean.
    Year refers to a calendar year.
    2. Use of Pb-PM10 Data as Surrogate Pb-TSP Data.
    (a) As stipulated in section 2.10 of Appendix C to 40 CFR part 58, 
at some mandatory Pb monitoring locations, monitoring agencies are 
required to sample for Pb as Pb-TSP, and at other mandatory Pb 
monitoring sites, monitoring agencies are permitted to monitor for Pb-
PM10 in lieu of Pb-TSP. In either situation, valid collocated 
Pb data for the other parameter may be produced. Additionally, there may 
be non-required monitoring locations that also produce valid Pb-TSP and/
or valid Pb-PM10 data. Pb-TSP data and Pb-PM10 
data are always processed separately when computing monthly and 3-month 
parameter means; monthly and 3-month parameter means are validated 
according to the criteria stated in section 4 of this appendix. Three-
month ``site'' means, which are the final valid 3-month mean from which 
a design value is identified, are determined from the one or two 
available valid 3-month parameter means according to the following 
prioritization which applies to all Pb monitoring locations.
    (i) Whenever a valid 3-month Pb-PM10 mean shows a 
violation and either is greater than a corresponding (collocated) 3-
month Pb-TSP mean or there is no corresponding valid 3-month Pb-TSP mean 
present, then that 3-month Pb-PM10 mean will be the site-
level mean for that (site's) 3-month period.
    (ii) Otherwise (i.e., there is no valid violating 3-month Pb-
PM10 that exceeds a corresponding 3-month Pb-TSP mean),
    (A) If a valid 3-month Pb-TSP mean exists, then it will be the site-
level mean for that (site's) 3-month period, or
    (B) If a valid 3-month Pb-TSP mean does not exist, then there is no 
valid 3-month site mean for that period (even if a valid non-violating 
3-month Pb-PM10 mean exists).
    (b) As noted in section 1(a) of this appendix, FRM/FEM Pb-
PM10 data will be processed at face value (i.e., at reported 
concentrations) without adjustment when computing means and making NAAQS 
comparisons.
    3. Requirements for Data Used for Comparisons With the Pb NAAQS and 
Data Reporting Considerations.
    (a) All valid FRM/FEM Pb-TSP data and all valid FRM/FEM Pb-
PM10 data submitted to EPA's Air Quality System (AQS), or 
otherwise available to EPA, meeting the requirements of part 58 of this 
chapter including appendices A, C, and E shall be used in design value 
calculations. Pb-TSP and Pb-PM10 data representing sample 
collection periods prior to January 1, 2009 (i.e., ``pre-rule'' data) 
will also be considered valid for NAAQS comparisons and related 
attainment/nonattainment determinations if the sampling and analysis 
methods that were utilized to collect that data were consistent with 
previous or newly designated FRMs or FEMs and with either the provisions 
of part 58 of this chapter including appendices A, C,

[[Page 157]]

and E that were in effect at the time of original sampling or that are 
in effect at the time of the attainment/nonattainment determination, and 
if such data are submitted to AQS prior to September 1, 2009.
    (b) Pb-TSP and Pb-PM10 measurement data are reported to 
AQS in units of micrograms per cubic meter ([micro]g/m\3\) at local 
conditions (local temperature and pressure, LC) to three decimal places; 
any additional digits to the right of the third decimal place are 
truncated. Pre-rule Pb-TSP and Pb-PM10 concentration data 
that were reported in standard conditions (standard temperature and 
standard pressure, STP) will not require a conversion to local 
conditions but rather, after truncating to three decimal places and 
processing as stated in this appendix, shall be compared ``as is'' to 
the NAAQS (i.e., the LC to STP conversion factor will be assumed to be 
one). However, if the monitoring agency has retroactively resubmitted 
Pb-TSP or Pb-PM10 pre-rule data converted from STP to LC 
based on suitable meteorological data, only the LC data will be used.
    (c) At each monitoring location (site), Pb-TSP and Pb-
PM10 data are to be processed separately when selecting daily 
data by day (as specified in section 3(d) of this appendix), when 
aggregating daily data by month (per section 6(a)), and when forming 3-
month means (per section 6(b)). However, when deriving (i.e., 
identifying) the design value for the 38-month period, 3-month means for 
the two data types may be considered together; see sections 2(a) and 
4(e) of this appendix for details.
    (d) Daily values for sites will be selected for a site on a size cut 
(Pb-TSP or Pb-PM10, i.e., ``parameter'') basis; Pb-TSP 
concentrations and Pb-PM10 concentrations shall not be 
commingled in these determinations. Site level, parameter-specific daily 
values will be selected as follows:
    (i) The starting dataset for a site-parameter shall consist of the 
measured daily concentrations recorded from the designated primary FRM/
FEM monitor for that parameter. The primary monitor for each parameter 
shall be designated in the appropriate state or local agency annual 
Monitoring Network Plan. If no primary monitor is designated, the 
Administrator will select which monitor to treat as primary. All daily 
values produced by the primary sampler are considered part of the site-
parameter data record (i.e., that site-parameter's set of daily values); 
this includes all creditable samples and all extra samples. For pre-rule 
Pb-TSP and Pb-PM10 data, valid data records present in AQS 
for the monitor with the lowest occurring Pollutant Occurrence Code 
(POC), as selected on a site-parameter-daily basis, will constitute the 
site-parameter data record. Where pre-rule Pb-TSP data (or subsequent 
non-required Pb-TSP or Pb-PM10 data) are reported in 
``composite'' form (i.e., multiple filters for a month of sampling that 
are analyzed together), the composite concentration will be used as the 
site-parameter monthly mean concentration if there are no valid daily 
Pb-TSP data reported for that month with a lower POC.
    (ii) Data for the primary monitor for each parameter shall be 
augmented as much as possible with data from collocated (same parameter) 
FRM/FEM monitors. If a valid 24-hour measurement is not produced from 
the primary monitor for a particular day (scheduled or otherwise), but a 
valid sample is generated by a collocated (same parameter) FRM/FEM 
instrument, then that collocated value shall be considered part of the 
site-parameter data record (i.e., that site-parameter's monthly set of 
daily values). If more than one valid collocated FRM/FEM value is 
available, the mean of those valid collocated values shall be used as 
the daily value. Note that this step will not be necessary for pre-rule 
data given the daily identification presumption for the primary monitor.
    (e) All daily values in the composite site-parameter record are used 
in monthly mean calculations. However, not all daily values are given 
credit towards data completeness requirements. Only ``creditable'' 
samples are given credit for data completeness. Creditable samples 
include valid samples on scheduled sampling days and valid make-up 
samples. All other types of daily values are referred to as ``extra'' 
samples. Make-up samples taken in the (first week of the) month after 
the one in which the miss/void occurred will be credited for data 
capture in the month of the miss/void but will be included in the month 
actually taken when computing monthly means. For example, if a make-up 
sample was taken in February to replace a missed sample scheduled for 
January, the make-up concentration would be included in the February 
monthly mean but the sample credited in the January data capture rate.
    4. Comparisons With the Pb NAAQS.
    (a) The Pb NAAQS is met at a monitoring site when the identified 
design value is valid and less than or equal to 0.15 micrograms per 
cubic meter ([micro]g/m\3\). A Pb design value that meets the NAAQS 
(i.e., 0.15 [micro]g/m\3\ or less), is considered valid if it 
encompasses 36 consecutive valid 3-month site means (specifically for a 
3-year calendar period and the two previous months). For sites that 
begin monitoring Pb after this rule is effective but before January 15, 
2010 (or January 15, 2011), a 2010-2012 (or 2011-2013) Pb design value 
that meets the NAAQS will be considered valid if it encompasses at least 
34 consecutive valid 3-month means (specifically encompassing only the 
3-year calendar period). See 4(c) of this appendix for the description 
of a valid 3-month mean and section 6(d) for the definition of the 
design value.

[[Page 158]]

    (b) The Pb NAAQS is violated at a monitoring site when the 
identified design value is valid and is greater than 0.15 [micro]g/m\3\, 
no matter whether determined from Pb-TSP or Pb-PM10 data. A 
Pb design value greater than 0.15 [micro]g/m\3\ is valid no matter how 
many valid 3-month means in the 3-year period it encompasses; that is, a 
violating design value is valid even if it (i.e., the highest 3-month 
mean) is the only valid 3-month mean in the 3-year timeframe. Further, a 
site does not have to monitor for three full calendar years in order to 
have a valid violating design value; a site could monitor just three 
months and still produce a valid (violating) design value.
    (c)(i) A 3-month parameter mean is considered valid (i.e., meets 
data completeness requirements) if the average of the data capture rate 
of the three constituent monthly means (i.e., the 3-month data capture 
rate) is greater than or equal to 75 percent. Monthly data capture rates 
(expressed as a percentage) are specifically calculated as the number of 
creditable samples for the month (including any make-up samples taken 
the subsequent month for missed samples in the month in question, and 
excluding any make-up samples taken in the month in question for missed 
samples in the previous month) divided by the number of scheduled 
samples for the month, the result then multiplied by 100 but not 
rounded. The 3-month data capture rate is the sum of the three 
corresponding unrounded monthly data capture rates divided by three and 
the result rounded to the nearest integer (zero decimal places). As 
noted in section 3(c), Pb-TSP and Pb-PM10 daily values are 
processed separately when calculating monthly means and data capture 
rates; a Pb-TSP value cannot be used as a make-up for a missing Pb-
PM10 value or vice versa. For purposes of assessing data 
capture, Pb-TSP and Pb-PM10 data collected before January 1, 
2009 will be treated with an assumed scheduled sampling frequency of 
every sixth day.
    (ii) A 3-month parameter mean that does not have at least 75 percent 
data capture and thus is not considered valid under 4(c)(i) shall be 
considered valid (and complete) if it passes either of the two following 
``data substitution'' tests, one such test for validating an above 
NAAQS-level (i.e., violating) 3-month Pb-TSP or Pb-PM10 mean 
(using actual ``low'' reported values from the same site at about the 
same time of the year (i.e., in the same month) looking across three or 
four years), and the second test for validating a below-NAAQS level 3-
month Pb-TSP mean (using actual ``high'' values reported for the same 
site at about the same time of the year (i.e., in the same month) 
looking across three or four years). Note that both tests are merely 
diagnostic in nature intending to confirm that there is a very high 
likelihood if not certainty that the original mean (the one with less 
than 75% data capture) reflects the true over/under NAAQS-level status 
for that 3-month period; the result of one of these data substitution 
tests (i.e., a ``test mean'', as defined in section 4(c)(ii)(A) or 
4(c)(ii)(B)) is not considered the actual 3-month parameter mean and 
shall not be used in the determination of design values. For both types 
of data substitution, substitution is permitted only if there are 
available data points from which to identify the high or low 3-year 
month-specific values, specifically if there are at least 10 data points 
total from at least two of the three (or four for November and December) 
possible year-months. Data substitution may only use data of the same 
parameter type.
    (A) The ``above NAAQS level'' test is as follows: Data substitution 
will be done in each month of the 3-month period that has less than 75 
percent data capture; monthly capture rates are temporarily rounded to 
integers (zero decimals) for this evaluation. If by substituting the 
lowest reported daily value for that month (year non-specific; e.g., for 
January) over the 38-month design value period in question for missing 
scheduled data in the deficient months (substituting only enough to meet 
the 75 percent data capture minimum), the computation yields a 
recalculated test 3-month parameter mean concentration above the level 
of the standard, then the 3-month period is deemed to have passed the 
diagnostic test and the level of the standard is deemed to have been 
exceeded in that 3-month period. As noted in section 4(c)(ii), in such a 
case, the 3-month parameter mean of the data actually reported, not the 
recalculated (``test'') result including the low values, shall be used 
to determine the design value.
    (B) The ``below NAAQS level'' test is as follows: Data substitution 
will be performed for each month of the 3-month period that has less 
than 75 percent but at least 50 percent data capture; if any month has 
less than 50% data capture then the 3-month mean can not utilize this 
substitution test. Also, incomplete 3-month Pb-PM10 means can 
not utilize this test. A 3-month Pb-TSP mean with less than 75% data 
capture shall still be considered valid (and complete) if, by 
substituting the highest reported daily value, month-specific, over the 
3-year design value period in question, for all missing scheduled data 
in the deficient months (i.e., bringing the data capture rate up to 
100%), the computation yields a recalculated 3-month parameter mean 
concentration equal or less than the level of the standard (0.15 
[micro]g/m\3\), then the 3-month mean is deemed to have passed the 
diagnostic test and the level of the standard is deemed not to have been 
exceeded in that 3-month period (for that parameter). As noted in 
section 4(c)(ii), in such a case, the 3-month parameter mean of the data 
actually reported, not the recalculated (``test'') result

[[Page 159]]

including the high values, shall be used to determine the design value.
    (d) Months that do not meet the completeness criteria stated in 
4(c)(i) or 4(c)(ii), and design values that do not meet the completeness 
criteria stated in 4(a) or 4(b), may also be considered valid (and 
complete) with the approval of, or at the initiative of, the 
Administrator, who may consider factors such as monitoring site 
closures/moves, monitoring diligence, the consistency and levels of the 
valid concentration measurements that are available, and nearby 
concentrations in determining whether to use such data.
    (e) The site-level design value for a 38-month period (three 
calendar years plus two previous months) is identified from the 
available (between one and 36) valid 3-month site means. In a situation 
where there are valid 3-month means for both parameters (Pb-TSP and Pb-
PM10), the mean originating from the reported Pb-TSP data 
will be the one deemed the site-level monthly mean and used in design 
value identifications unless the Pb-PM10 mean shows a 
violation of the NAAQS and exceeds the Pb-TSP mean; see section 2(a) for 
details. A monitoring site will have only one site-level 3-month mean 
per 3-month period; however, the set of site-level 3-month means 
considered for design value identification (i.e., one to 36 site-level 
3-month means) can be a combination of Pb-TSP and Pb-PM10 
data.
    (f) The procedures for calculating monthly means and 3-month means, 
and identifying Pb design values are given in section 6 of this 
appendix.
    5. Rounding Conventions.
    (a) Monthly means and monthly data capture rates are not rounded.
    (b) Three-month means shall be rounded to the nearest hundredth 
[micro]g/m\3\ (0.xx). Decimals 0.xx5 and greater are rounded up, and any 
decimal lower than 0.xx5 is rounded down. E.g., a 3-month mean of 
0.104925 rounds to 0.10 and a 3-month mean of .10500 rounds to 0.11. 
Three-month data capture rates, expressed as a percent, are round to 
zero decimal places.
    (c) Because a Pb design value is simply a (highest) 3-month mean and 
because the NAAQS level is stated to two decimal places, no additional 
rounding beyond what is specified for 3-month means is required before a 
design value is compared to the NAAQS.
    6. Procedures and Equations for the Pb NAAQS.
    (a)(i) A monthly mean value for Pb-TSP (or Pb-PM10) is 
determined by averaging the daily values of a calendar month using 
equation 1 of this appendix, unless the Administrator chooses to 
exercise his discretion to use the alternate approach described in 
6(a)(ii).
[GRAPHIC] [TIFF OMITTED] TR12NO08.001

Where:

Xm,y,s = the mean for month m of the year y for sites; and
nm = the number of daily values in the month (creditable plus extra 
          samples); and
Xi,m,y,s = the i\th\ value in month m for year y for site s.

    (a)(ii) The Administrator may at his discretion use the following 
alternate approach to calculating the monthly mean concentration if the 
number of extra sampling days during a month is greater than the number 
of successfully completed scheduled and make-up sample days in that 
month. In exercising his discretion, the Administrator will consider 
whether the approach specified in 6(a)(i) might in the Administrator's 
judgment result in an unrepresentative value for the monthly mean 
concentration. This provision is to protect the integrity of the monthly 
and 3-month mean concentration values in situations in which, by 
intention or otherwise, extra sampling days are concentrated in a period 
during which ambient concentrations are particularly high or low. The 
alternate approach is to average all extra and make-up samples (in the 
given month) taken after each scheduled sampling day (``Day X'') and 
before the next scheduled sampling day (e.g., ``Day X + 6'', in the case 
of one-in-six sampling) with the sample taken on Day X (assuming valid 
data was obtained on the scheduled sampling day), and then averaging 
these averages to calculate the monthly mean. This approach has the 
effect of giving approximately equal weight to periods during a month 
that have equal number of days, regardless of how many samples were 
actually obtained during the periods, thus mitigating the potential for 
the monthly mean to be distorted. The first day of scheduled sampling 
typically will not fall on the first day of the calendar month, and 
there may be make-up and/or extra samples (in that same calendar month) 
preceding the first scheduled day of the month. These samples will not 
be shifted into the previous month's mean concentration, but rather will 
stay associated with their actual calendar month as follows. Any extra 
and make-up samples taken in a month before the first scheduled sampling 
day of the month will be associated with and averaged with the last 
scheduled sampling day of that same month.
    (b) Three-month parameter means are determined by averaging three 
consecutive monthly means of the same parameter using Equation 2 of this 
appendix.

[[Page 160]]

[GRAPHIC] [TIFF OMITTED] TR12NO08.002

Where:

Xm1, m2, m3; s = the 3-month parameter mean for months m1, m2, and m3 
          for site s; and
nm = the number of monthly means available to be averaged (typically 3, 
          sometimes 1 or 2 if one or two months have no valid daily 
          values); and
Xm, y: z, s = The mean for month m of the year y (or z) for site s.

    (c) Three-month site means are determined from available 3-month 
parameter means according to the hierarchy established in 2(a) of this 
appendix.
    (d) The site-level Pb design value is the highest valid 3-month 
site-level mean over the most recent 38-month period (i.e., the most 
recent 3-year calendar period plus two previous months). Section 4(a) of 
this appendix explains when the identified design value is itself 
considered valid for purposes of determining that the NAAQS is met or 
violated at a site.

[73 FR 67054, Nov. 12, 2008]



   Sec. Appendix S to Part 50--Interpretation of the Primary National 
 Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide)

                               1. General

    (a) This appendix explains the data handling conventions and 
computations necessary for determining when the primary national ambient 
air quality standards for oxides of nitrogen as measured by nitrogen 
dioxide (``NO2 NAAQS'') specified in 50.11 are met. Nitrogen 
dioxide (NO2) is measured in the ambient air by a Federal 
reference method (FRM) based on appendix F to this part or by a Federal 
equivalent method (FEM) designated in accordance with part 53 of this 
chapter. Data handling and computation procedures to be used in making 
comparisons between reported NO2 concentrations and the 
levels of the NO2 NAAQS are specified in the following 
sections.
    (b) Whether to exclude, retain, or make adjustments to the data 
affected by exceptional events, including natural events, is determined 
by the requirements and process deadlines specified in 50.1, 50.14 and 
51.930 of this chapter.
    (c) The terms used in this appendix are defined as follows:
    Annual mean refers to the annual average of all of the 1-hour 
concentration values as defined in section 5.1 of this appendix.
    Daily maximum 1-hour values for NO2 refers to the maximum 
1-hour NO2 concentration values measured from midnight to 
midnight (local standard time) that are used in NAAQS computations.
    Design values are the metrics (i.e., statistics) that are compared 
to the NAAQS levels to determine compliance, calculated as specified in 
section 5 of this appendix. The design values for the primary NAAQS are:
    (1) The annual mean value for a monitoring site for one year 
(referred to as the ``annual primary standard design value'').
    (2) The 3-year average of annual 98th percentile daily maximum 1-
hour values for a monitoring site (referred to as the ``1-hour primary 
standard design value'').
    98th percentile daily maximum 1-hour value is the value below which 
nominally 98 percent of all daily maximum 1-hour concentration values 
fall, using the ranking and selection method specified in section 5.2 of 
this appendix.
    Quarter refers to a calendar quarter.
    Year refers to a calendar year.

 2. Requirements for Data Used for Comparisons With the NO2 
                 NAAQS and Data Reporting Considerations

    (a) All valid FRM/FEM NO2 hourly data required to be 
submitted to EPA's Air Quality System (AQS), or otherwise available to 
EPA, meeting the requirements of part 58 of this chapter including 
appendices A, C, and E shall be used in design value calculations. 
Multi-hour average concentration values collected by wet chemistry 
methods shall not be used.
    (b) When two or more NO2 monitors are operated at a site, 
the State may in advance designate one of them as the primary monitor. 
If the State has not made this designation, the Administrator will make 
the designation, either in advance or retrospectively. Design values 
will be developed using only the data from the primary monitor, if this 
results in a valid design value. If data from the primary monitor do not 
allow the development of a valid design value, data solely from the 
other monitor(s) will be used in turn to develop a valid design value, 
if this results in a valid design value. If there are three or more 
monitors, the order for such comparison of the other monitors will be 
determined by the Administrator. The Administrator may combine data from 
different monitors in different years for the purpose of developing a 
valid 1-hour primary standard design value, if a valid design value 
cannot be developed solely with the data from a single monitor. However, 
data from two or more monitors in the same year at the same site will 
not be combined in an attempt to meet data completeness requirements, 
except if one monitor has physically replaced another instrument 
permanently, in

[[Page 161]]

which case the two instruments will be considered to be the same 
monitor, or if the State has switched the designation of the primary 
monitor from one instrument to another during the year.
    (c) Hourly NO2 measurement data shall be reported to AQS 
in units of parts per billion (ppb), to at most one place after the 
decimal, with additional digits to the right being truncated with no 
further rounding.

              3. Comparisons With the NO2 NAAQS

                    3.1 The Annual Primary NO2 NAAQS

    (a) The annual primary NO2 NAAQS is met at a site when 
the valid annual primary standard design value is less than or equal to 
53 parts per billion (ppb).
    (b) An annual primary standard design value is valid when at least 
75 percent of the hours in the year are reported.
    (c) An annual primary standard design value based on data that do 
not meet the completeness criteria stated in section 3.1(b) may also be 
considered valid with the approval of, or at the initiative of, the 
Administrator, who may consider factors such as monitoring site 
closures/moves, monitoring diligence, the consistency and levels of the 
valid concentration measurements that are available, and nearby 
concentrations in determining whether to use such data.
    (d) The procedures for calculating the annual primary standard 
design values are given in section 5.1 of this appendix.

                    3.2 The 1-hour Primary NO2 NAAQS

    (a) The 1-hour primary NO2 NAAQS is met at a site when 
the valid 1-hour primary standard design value is less than or equal to 
100 parts per billion (ppb).
    (b) An NO2 1-hour primary standard design value is valid 
if it encompasses three consecutive calendar years of complete data. A 
year meets data completeness requirements when all 4 quarters are 
complete. A quarter is complete when at least 75 percent of the sampling 
days for each quarter have complete data. A sampling day has complete 
data if 75 percent of the hourly concentration values, including State-
flagged data affected by exceptional events which have been approved for 
exclusion by the Administrator, are reported.
    (c) In the case of one, two, or three years that do not meet the 
completeness requirements of section 3.2(b) of this appendix and thus 
would normally not be useable for the calculation of a valid 3-year 1-
hour primary standard design value, the 3-year 1-hour primary standard 
design value shall nevertheless be considered valid if one of the 
following conditions is true.
    (i) At least 75 percent of the days in each quarter of each of three 
consecutive years have at least one reported hourly value, and the 
design value calculated according to the procedures specified in section 
5.2 is above the level of the primary 1-hour standard.
    (ii)(A) A 1-hour primary standard design value that is below the 
level of the NAAQS can be validated if the substitution test in section 
3.2(c)(ii)(B) results in a ``test design value'' that is below the level 
of the NAAQS. The test substitutes actual ``high'' reported daily 
maximum 1-hour values from the same site at about the same time of the 
year (specifically, in the same calendar quarter) for unknown values 
that were not successfully measured. Note that the test is merely 
diagnostic in nature, intended to confirm that there is a very high 
likelihood that the original design value (the one with less than 75 
percent data capture of hours by day and of days by quarter) reflects 
the true under-NAAQS-level status for that 3-year period; the result of 
this data substitution test (the ``test design value'', as defined in 
section 3.2(c)(ii)(B)) is not considered the actual design value. For 
this test, substitution is permitted only if there are at least 200 days 
across the three matching quarters of the three years under 
consideration (which is about 75 percent of all possible daily values in 
those three quarters) for which 75 percent of the hours in the day, 
including State-flagged data affected by exceptional events which have 
been approved for exclusion by the Administrator, have reported 
concentrations. However, maximum 1-hour values from days with less than 
75 percent of the hours reported shall also be considered in identifying 
the high value to be used for substitution.
    (B) The substitution test is as follows: Data substitution will be 
performed in all quarter periods that have less than 75 percent data 
capture but at least 50 percent data capture, including State-flagged 
data affected by exceptional events which have been approved for 
exclusion by the Administrator; if any quarter has less than 50 percent 
data capture then this substitution test cannot be used. Identify for 
each quarter (e.g., January-March) the highest reported daily maximum 1-
hour value for that quarter, excluding State-flagged data affected by 
exceptional events which have been approved for exclusion by the 
Administrator, looking across those three months of all three years 
under consideration. All daily maximum 1-hour values from all days in 
the quarter period shall be considered when identifying this highest 
value, including days with less than 75 percent data capture. If after 
substituting the highest non-excluded reported daily maximum 1-hour 
value for a quarter for as much of the missing daily data in the 
matching deficient quarter(s) as is needed to make them 100 percent 
complete, the procedure in section 5.2 yields a recalculated 3-year 1-
hour standard ``test design value'' below the level of the standard, 
then the 1-hour primary standard design value is deemed to have

[[Page 162]]

passed the diagnostic test and is valid, and the level of the standard 
is deemed to have been met in that 3-year period. As noted in section 
3.2(c)(i), in such a case, the 3-year design value based on the data 
actually reported, not the ``test design value'', shall be used as the 
valid design value.
    (iii)(A) A 1-hour primary standard design value that is above the 
level of the NAAQS can be validated if the substitution test in section 
3.2(c)(iii)(B) results in a ``test design value'' that is above the 
level of the NAAQS. The test substitutes actual ``low'' reported daily 
maximum 1-hour values from the same site at about the same time of the 
year (specifically, in the same three months of the calendar) for 
unknown values that were not successfully measured. Note that the test 
is merely diagnostic in nature, intended to confirm that there is a very 
high likelihood that the original design value (the one with less than 
75 percent data capture of hours by day and of days by quarter) reflects 
the true above-NAAQS-level status for that 3-year period; the result of 
this data substitution test (the ``test design value'', as defined in 
section 3.2(c)(iii)(B)) is not considered the actual design value. For 
this test, substitution is permitted only if there are a minimum number 
of available daily data points from which to identify the low quarter-
specific daily maximum 1-hour values, specifically if there are at least 
200 days across the three matching quarters of the three years under 
consideration (which is about 75 percent of all possible daily values in 
those three quarters) for which 75 percent of the hours in the day have 
reported concentrations. Only days with at least 75 percent of the hours 
reported shall be considered in identifying the low value to be used for 
substitution.
    (B) The substitution test is as follows: Data substitution will be 
performed in all quarter periods that have less than 75 percent data 
capture. Identify for each quarter (e.g., January-March) the lowest 
reported daily maximum 1-hour value for that quarter, looking across 
those three months of all three years under consideration. All daily 
maximum 1-hour values from all days with at least 75 percent capture in 
the quarter period shall be considered when identifying this lowest 
value. If after substituting the lowest reported daily maximum 1-hour 
value for a quarter for as much of the missing daily data in the 
matching deficient quarter(s) as is needed to make them 75 percent 
complete, the procedure in section 5.2 yields a recalculated 3-year 1-
hour standard ``test design value'' above the level of the standard, 
then the 1-hour primary standard design value is deemed to have passed 
the diagnostic test and is valid, and the level of the standard is 
deemed to have been exceeded in that 3-year period. As noted in section 
3.2(c)(i), in such a case, the 3-year design value based on the data 
actually reported, not the ``test design value'', shall be used as the 
valid design value.
    (d) A 1-hour primary standard design value based on data that do not 
meet the completeness criteria stated in 3.2(b) and also do not satisfy 
section 3.2(c), may also be considered valid with the approval of, or at 
the initiative of, the Administrator, who may consider factors such as 
monitoring site closures/moves, monitoring diligence, the consistency 
and levels of the valid concentration measurements that are available, 
and nearby concentrations in determining whether to use such data.
    (e) The procedures for calculating the 1-hour primary standard 
design values are given in section 5.2 of this appendix.

                         4. Rounding Conventions

        4.1 Rounding Conventions for the Annual Primary NO2 NAAQS

    (a) Hourly NO2 measurement data shall be reported to AQS 
in units of parts per billion (ppb), to at most one place after the 
decimal, with additional digits to the right being truncated with no 
further rounding.
    (b) The annual primary standard design value is calculated pursuant 
to section 5.1 and then rounded to the nearest whole number or 1 ppb 
(decimals 0.5 and greater are rounded up to the nearest whole number, 
and any decimal lower than 0.5 is rounded down to the nearest whole 
number).

        4.2 Rounding Conventions for the 1-hour Primary NO2 NAAQS

    (a) Hourly NO2 measurement data shall be reported to AQS 
in units of parts per billion (ppb), to at most one place after the 
decimal, with additional digits to the right being truncated with no 
further rounding.
    (b) Daily maximum 1-hour values are not rounded.
    (c) The 1-hour primary standard design value is calculated pursuant 
to section 5.2 and then rounded to the nearest whole number or 1 ppb 
(decimals 0.5 and greater are rounded up to the nearest whole number, 
and any decimal lower than 0.5 is rounded down to the nearest whole 
number).

     5. Calculation Procedures for the Primary NO2 NAAQS

             5.1 Procedures for the Annual Primary NO2 NAAQS

    (a) When the data for a site and year meet the data completeness 
requirements in section 3.1(b) of this appendix, or if the Administrator 
exercises the discretionary authority in section 3.1(c), the annual mean 
is simply the arithmetic average of all of the reported 1-hour values.
    (b) The annual primary standard design value for a site is the valid 
annual mean

[[Page 163]]

rounded according to the conventions in section 4.1.

       5.2 Calculation Procedures for the 1-hour Primary NO2 NAAQS

    (a) Procedure for identifying annual 98th percentile values. When 
the data for a particular site and year meet the data completeness 
requirements in section 3.2(b), or if one of the conditions of section 
3.2(c) is met, or if the Administrator exercises the discretionary 
authority in section 3.2(d), identification of annual 98th percentile 
value is accomplished as follows.
    (i) The annual 98th percentile value for a year is the higher of the 
two values resulting from the following two procedures.
    (1) Procedure 1.
    (A) For the year, determine the number of days with at least 75 
percent of the hourly values reported including State-flagged data 
affected by exceptional events which have been approved for exclusion by 
the Administrator.
    (B) For the year, from only the days with at least 75 percent of the 
hourly values reported, select from each day the maximum hourly value 
excluding State-flagged data affected by exceptional events which have 
been approved for exclusion by the Administrator.
    (C) Sort all these daily maximum hourly values from a particular 
site and year by descending value. (For example: (x[1], x[2], x[3], * * 
*, x[n]). In this case, x[1] is the largest number and x[n] is the 
smallest value.) The 98th percentile is determined from this sorted 
series of daily values which is ordered from the highest to the lowest 
number. Using the left column of Table 1, determine the appropriate 
range (i.e., row) for the annual number of days with valid data for year 
y (cny) as determined from step (A). The corresponding ``n'' 
value in the right column identifies the rank of the annual 98th 
percentile value in the descending sorted list of daily site values for 
year y. Thus, P0.98, y = the nth largest value.
    (2) Procedure 2.
    (A) For the year, determine the number of days with at least one 
hourly value reported including State-flagged data affected by 
exceptional events which have been approved for exclusion by the 
Administrator.
    (B) For the year, from all the days with at least one hourly value 
reported, select from each day the maximum hourly value excluding State-
flagged data affected by exceptional events which have been approved for 
exclusion by the Administrator.
    (C) Sort all these daily maximum values from a particular site and 
year by descending value. (For example: (x[1], x[2], x[3], * * *, x[n]). 
In this case, x[1] is the largest number and x[n] is the smallest 
value.) The 98th percentile is determined from this sorted series of 
daily values which is ordered from the highest to the lowest number. 
Using the left column of Table 1, determine the appropriate range (i.e., 
row) for the annual number of days with valid data for year y 
(cny) as determined from step (A). The corresponding ``n'' 
value in the right column identifies the rank of the annual 98th 
percentile value in the descending sorted list of daily site values for 
year y. Thus, P0.98, y = the nth largest value.
    (b) The 1-hour primary standard design value for a site is mean of 
the three annual 98th percentile values, rounded according to the 
conventions in section 4.

                                 Table 1
------------------------------------------------------------------------
                                                        P0.98, y is the
                                                       nth maximum value
Annual number of days with valid data for year ``y''  of the year, where
                        (cny)                           n is the listed
                                                            number
------------------------------------------------------------------------
1-50................................................                  1
51-100..............................................                  2
101-150.............................................                  3
151-200.............................................                  4
201-250.............................................                  5
251-300.............................................                  6
301-350.............................................                  7
351-366.............................................                  8
------------------------------------------------------------------------


[75 FR 6532, Feb. 9, 2010]



   Sec. Appendix T to Part 50--Interpretation of the Primary National 
   Ambient Air Quality Standards for Oxides of Sulfur (Sulfur Dioxide)

                               1. General

    (a) This appendix explains the data handling conventions and 
computations necessary for determining when the primary national ambient 
air quality standards for Oxides of Sulfur as measured by Sulfur Dioxide 
(``SO2 NAAQS'') specified in Sec. 50.17 are met at an 
ambient air quality monitoring site. Sulfur Dioxide (SO2) is 
measured in the ambient air by a Federal reference method (FRM) based on 
appendix A or A-1 to this part or by a Federal equivalent method (FEM) 
designated in accordance with part 53 of this chapter. Data handling and 
computation procedures to be used in making comparisons between reported 
SO2 concentrations and the levels of the SO2 NAAQS 
are specified in the following sections.
    (b) Decisions to exclude, retain, or make adjustments to the data 
affected by exceptional events, including natural events, are made 
according to the requirements and process deadlines specified in 
Sec. Sec. 50.1, 50.14 and 51.930 of this chapter.
    (c) The terms used in this appendix are defined as follows:
    Daily maximum 1-hour values for SO2 refers to the maximum 
1-hour SO2 concentration

[[Page 164]]

values measured from midnight to midnight (local standard time) that are 
used in NAAQS computations.
    Design values are the metrics (i.e., statistics) that are compared 
to the NAAQS levels to determine compliance, calculated as specified in 
section 5 of this appendix. The design value for the primary 1-hour 
NAAQS is the 3-year average of annual 99th percentile daily maximum 1-
hour values for a monitoring site (referred to as the ``1-hour primary 
standard design value'').
    99th percentile daily maximum 1-hour value is the value below which 
nominally 99 percent of all daily maximum 1-hour concentration values 
fall, using the ranking and selection method specified in section 5 of 
this appendix.
    Pollutant Occurrence Code (POC) refers to a numerical code (1, 2, 3, 
etc.) used to distinguish the data from two or more monitors for the 
same parameter at a single monitoring site.
    Quarter refers to a calendar quarter.
    Year refers to a calendar year.

 2. Requirements for Data Used for Comparisons With the SO2 
                 NAAQS and Data Reporting Considerations

    (a) All valid FRM/FEM SO2 hourly data required to be 
submitted to EPA's Air Quality System (AQS), or otherwise available to 
EPA, meeting the requirements of part 58 of this chapter including 
appendices A, C, and E shall be used in design value calculations. 
Multi-hour average concentration values collected by wet chemistry 
methods shall not be used.
    (b) Data from two or more monitors from the same year at the same 
site reported to EPA under distinct Pollutant Occurrence Codes shall not 
be combined in an attempt to meet data completeness requirements. The 
Administrator will combine annual 99th percentile daily maximum 
concentration values from different monitors in different years, 
selected as described here, for the purpose of developing a valid 1-hour 
primary standard design value. If more than one of the monitors meets 
the completeness requirement for all four quarters of a year, the steps 
specified in section 5(a) of this appendix shall be applied to the data 
from the monitor with the highest average of the four quarterly 
completeness values to derive a valid annual 99th percentile daily 
maximum concentration. If no monitor is complete for all four quarters 
in a year, the steps specified in section 3(c) and 5(a) of this appendix 
shall be applied to the data from the monitor with the highest average 
of the four quarterly completeness values in an attempt to derive a 
valid annual 99th percentile daily maximum concentration. This paragraph 
does not prohibit a monitoring agency from making a local designation of 
one physical monitor as the primary monitor for a Pollutant Occurrence 
Code and substituting the 1-hour data from a second physical monitor 
whenever a valid concentration value is not obtained from the primary 
monitor; if a monitoring agency substitutes data in this manner, each 
substituted value must be accompanied by an AQS qualifier code 
indicating that substitution with a value from a second physical monitor 
has taken place.
    (c) Hourly SO2 measurement data shall be reported to AQS 
in units of parts per billion (ppb), to at most one place after the 
decimal, with additional digits to the right being truncated with no 
further rounding.

       3. Comparisons With the 1-Hour Primary SO2 NAAQS

    (a) The 1-hour primary SO2 NAAQS is met at an ambient air 
quality monitoring site when the valid 1-hour primary standard design 
value is less than or equal to 75 parts per billion (ppb).
    (b) An SO2 1-hour primary standard design value is valid 
if it encompasses three consecutive calendar years of complete data. A 
year meets data completeness requirements when all 4 quarters are 
complete. A quarter is complete when at least 75 percent of the sampling 
days for each quarter have complete data. A sampling day has complete 
data if 75 percent of the hourly concentration values, including State-
flagged data affected by exceptional events which have been approved for 
exclusion by the Administrator, are reported.
    (c) In the case of one, two, or three years that do not meet the 
completeness requirements of section 3(b) of this appendix and thus 
would normally not be useable for the calculation of a valid 3-year 1-
hour primary standard design value, the 3-year 1-hour primary standard 
design value shall nevertheless be considered valid if one of the 
following conditions is true.
    (i) At least 75 percent of the days in each quarter of each of three 
consecutive years have at least one reported hourly value, and the 
design value calculated according to the procedures specified in section 
5 is above the level of the primary 1-hour standard.
    (ii)(A) A 1-hour primary standard design value that is equal to or 
below the level of the NAAQS can be validated if the substitution test 
in section 3(c)(ii)(B) results in a ``test design value'' that is below 
the level of the NAAQS. The test substitutes actual ``high'' reported 
daily maximum 1-hour values from the same site at about the same time of 
the year (specifically, in the same calendar quarter) for unknown values 
that were not successfully measured. Note that the test is merely 
diagnostic in nature, intended to confirm that there is a very high 
likelihood that the original design value (the one with less than 75 
percent data capture of hours by day and of days by quarter) reflects 
the true under-NAAQS-level status for that

[[Page 165]]

3-year period; the result of this data substitution test (the ``test 
design value'', as defined in section 3(c)(ii)(B)) is not considered the 
actual design value. For this test, substitution is permitted only if 
there are at least 200 days across the three matching quarters of the 
three years under consideration (which is about 75 percent of all 
possible daily values in those three quarters) for which 75 percent of 
the hours in the day, including State-flagged data affected by 
exceptional events which have been approved for exclusion by the 
Administrator, have reported concentrations. However, maximum 1-hour 
values from days with less than 75 percent of the hours reported shall 
also be considered in identifying the high value to be used for 
substitution.
    (B) The substitution test is as follows: Data substitution will be 
performed in all quarter periods that have less than 75 percent data 
capture but at least 50 percent data capture, including State-flagged 
data affected by exceptional events which have been approved for 
exclusion by the Administrator; if any quarter has less than 50 percent 
data capture then this substitution test cannot be used. Identify for 
each quarter (e.g., January-March) the highest reported daily maximum 1-
hour value for that quarter, excluding State-flagged data affected by 
exceptional events which have been approved for exclusion by the 
Administrator, looking across those three months of all three years 
under consideration. All daily maximum 1-hour values from all days in 
the quarter period shall be considered when identifying this highest 
value, including days with less than 75 percent data capture. If after 
substituting the highest reported daily maximum 1-hour value for a 
quarter for as much of the missing daily data in the matching deficient 
quarter(s) as is needed to make them 100 percent complete, the procedure 
in section 5 yields a recalculated 3-year 1-hour standard ``test design 
value'' less than or equal to the level of the standard, then the 1-hour 
primary standard design value is deemed to have passed the diagnostic 
test and is valid, and the level of the standard is deemed to have been 
met in that 3-year period. As noted in section 3(c)(i), in such a case, 
the 3-year design value based on the data actually reported, not the 
``test design value'', shall be used as the valid design value.
    (iii)(A) A 1-hour primary standard design value that is above the 
level of the NAAQS can be validated if the substitution test in section 
3(c)(iii)(B) results in a ``test design value'' that is above the level 
of the NAAQS. The test substitutes actual ``low'' reported daily maximum 
1-hour values from the same site at about the same time of the year 
(specifically, in the same three months of the calendar) for unknown 
hourly values that were not successfully measured. Note that the test is 
merely diagnostic in nature, intended to confirm that there is a very 
high likelihood that the original design value (the one with less than 
75 percent data capture of hours by day and of days by quarter) reflects 
the true above-NAAQS-level status for that 3-year period; the result of 
this data substitution test (the ``test design value'', as defined in 
section 3(c)(iii)(B)) is not considered the actual design value. For 
this test, substitution is permitted only if there are a minimum number 
of available daily data points from which to identify the low quarter-
specific daily maximum 1-hour values, specifically if there are at least 
200 days across the three matching quarters of the three years under 
consideration (which is about 75 percent of all possible daily values in 
those three quarters) for which 75 percent of the hours in the day have 
reported concentrations. Only days with at least 75 percent of the hours 
reported shall be considered in identifying the low value to be used for 
substitution.
    (B) The substitution test is as follows: Data substitution will be 
performed in all quarter periods that have less than 75 percent data 
capture. Identify for each quarter (e.g., January-March) the lowest 
reported daily maximum 1-hour value for that quarter, looking across 
those three months of all three years under consideration. All daily 
maximum 1-hour values from all days with at least 75 percent capture in 
the quarter period shall be considered when identifying this lowest 
value. If after substituting the lowest reported daily maximum 1-hour 
value for a quarter for as much of the missing daily data in the 
matching deficient quarter(s) as is needed to make them 75 percent 
complete, the procedure in section 5 yields a recalculated 3-year 1-hour 
standard ``test design value'' above the level of the standard, then the 
1-hour primary standard design value is deemed to have passed the 
diagnostic test and is valid, and the level of the standard is deemed to 
have been exceeded in that 3-year period. As noted in section 3(c)(i), 
in such a case, the 3-year design value based on the data actually 
reported, not the ``test design value'', shall be used as the valid 
design value.
    (d) A 1-hour primary standard design value based on data that do not 
meet the completeness criteria stated in 3(b) and also do not satisfy 
section 3(c), may also be considered valid with the approval of, or at 
the initiative of, the Administrator, who may consider factors such as 
monitoring site closures/moves, monitoring diligence, the consistency 
and levels of the valid concentration measurements that are available, 
and nearby concentrations in determining whether to use such data.
    (e) The procedures for calculating the 1-hour primary standard 
design values are given in section 5 of this appendix.

[[Page 166]]

   4. Rounding Conventions for the 1-Hour Primary SO2 NAAQS

    (a) Hourly SO2 measurement data shall be reported to AQS 
in units of parts per billion (ppb), to at most one place after the 
decimal, with additional digits to the right being truncated with no 
further rounding.
    (b) Daily maximum 1-hour values and therefore the annual 99th 
percentile of those daily values are not rounded.
    (c) The 1-hour primary standard design value is calculated pursuant 
to section 5 and then rounded to the nearest whole number or 1 ppb 
(decimals 0.5 and greater are rounded up to the nearest whole number, 
and any decimal lower than 0.5 is rounded down to the nearest whole 
number).

  5. Calculation Procedures for the 1-Hour Primary SO2 NAAQS

    (a) Procedure for identifying annual 99th percentile values. When 
the data for a particular ambient air quality monitoring site and year 
meet the data completeness requirements in section 3(b), or if one of 
the conditions of section 3(c) is met, or if the Administrator exercises 
the discretionary authority in section 3(d), identification of annual 
99th percentile value is accomplished as follows.
    (i) The annual 99th percentile value for a year is the higher of the 
two values resulting from the following two procedures.
    (1) Procedure 1. For the year, determine the number of days with at 
least 75 percent of the hourly values reported.
    (A) For the year, determine the number of days with at least 75 
percent of the hourly values reported including State-flagged data 
affected by exceptional events which have been approved for exclusion by 
the Administrator.
    (B) For the year, from only the days with at least 75 percent of the 
hourly values reported, select from each day the maximum hourly value 
excluding State-flagged data affected by exceptional events which have 
been approved for exclusion by the Administrator.
    (C) Sort all these daily maximum hourly values from a particular 
site and year by descending value. (For example: (x[1], x[2], x[3], * * 
*, x[n]). In this case, x[1] is the largest number and x[n] is the 
smallest value.) The 99th percentile is determined from this sorted 
series of daily values which is ordered from the highest to the lowest 
number. Using the left column of Table 1, determine the appropriate 
range (i.e., row) for the annual number of days with valid data for year 
y (cny). The corresponding ``n'' value in the right column 
identifies the rank of the annual 99th percentile value in the 
descending sorted list of daily site values for year y. Thus, 
P0.99, y = the nth largest value.
    (2) Procedure 2. For the year, determine the number of days with at 
least one hourly value reported.
    (A) For the year, determine the number of days with at least one 
hourly value reported including State-flagged data affected by 
exceptional events which have been approved for exclusion by the 
Administrator.
    (B) For the year, from all the days with at least one hourly value 
reported, select from each day the maximum hourly value excluding State-
flagged data affected by exceptional events which have been approved for 
exclusion by the Administrator.
    (C) Sort all these daily maximum values from a particular site and 
year by descending value. (For example: (x[1], x[2], x[3], * * *, x[n]). 
In this case, x[1] is the largest number and x[n] is the smallest 
value.) The 99th percentile is determined from this sorted series of 
daily values which is ordered from the highest to the lowest number. 
Using the left column of Table 1, determine the appropriate range (i.e., 
row) for the annual number of days with valid data for year y 
(cny). The corresponding ``n'' value in the right column 
identifies the rank of the annual 99th percentile value in the 
descending sorted list of daily site values for year y. Thus, 
P0.99,y = the nth largest value.
    (b) The 1-hour primary standard design value for an ambient air 
quality monitoring site is mean of the three annual 99th percentile 
values, rounded according to the conventions in section 4.

                                 Table 1
------------------------------------------------------------------------
                                                     P0.99,y is the nth
  Annual number of days with valid data for year    maximum value of the
                    ``y'' (cny)                     year, where n is the
                                                        listed number
------------------------------------------------------------------------
1-100.............................................                     1
101-200...........................................                     2
201-300...........................................                     3
301-366...........................................                     4
------------------------------------------------------------------------


[75 FR 35595, June 23, 2010]



Sec. Appendix U to Part 50--Interpretation of the Primary and Secondary 
            National Ambient Air Quality Standards for Ozone

                               1. General

    (a) This appendix explains the data handling conventions and 
computations necessary for determining whether the primary and secondary 
national ambient air quality standards (NAAQS) for ozone (O3) 
specified in Sec. 50.19 are met at an ambient O3 air quality 
monitoring site. Data reporting, data handling, and computation 
procedures to be used in making comparisons between reported 
O3 concentrations and the levels of the O3 NAAQS 
are specified in the following sections.
    (b) Whether to exclude or retain the data affected by exceptional 
events is determined

[[Page 167]]

by the requirements under Sec. Sec. 50.1, 50.14 and 51.930.
    (c) The terms used in this appendix are defined as follows:
    8-hour average refers to the moving average of eight consecutive 
hourly O3 concentrations measured at a site, as explained in 
section 3 of this appendix.
    Annual fourth-highest daily maximum refers to the fourth highest 
value measured at a site during a year.
    Collocated monitors refers to the instance of two or more 
O3 monitors operating at the same physical location.
    Daily maximum 8-hour average O3 concentration refers to the maximum 
calculated 8-hour average value measured at a site on a particular day, 
as explained in section 3 of this appendix.
    Design value refers to the metric (i.e., statistic) that is used to 
compare ambient O3 concentration data measured at a site to 
the NAAQS in order to determine compliance, as explained in section 4 of 
this appendix.
    Minimum data completeness requirements refer to the amount of data 
that a site is required to collect in order to make a valid 
determination that the site is meeting the NAAQS.
    Monitor refers to a physical instrument used to measure ambient 
O3 concentrations.
    O3 monitoring season refers to the span of time within a 
year when individual states are required to measure ambient 
O3 concentrations, as listed in Appendix D to part 58 of this 
chapter.
    Site refers to an ambient O3 air quality monitoring site.
    Site data record refers to the set of hourly O3 
concentration data collected at a site for use in comparisons with the 
NAAQS.
    Year refers to calendar year.

    2. Selection of Data for use in Comparisons With the Primary and 
                          Secondary Ozone NAAQS

    (a) All valid hourly O3 concentration data collected 
using a federal reference method specified in Appendix D to this part, 
or an equivalent method designated in accordance with part 53 of this 
chapter, meeting all applicable requirements in part 58 of this chapter, 
and submitted to EPA's Air Quality System (AQS) database or otherwise 
available to EPA, shall be used in design value calculations.
    (b) All design value calculations shall be implemented on a site-
level basis. If data are reported to EPA from collocated monitors, those 
data shall be combined into a single site data record as follows:
    (i) The monitoring agency shall designate one monitor as the primary 
monitor for the site.
    (ii) Hourly O3 concentration data from a secondary 
monitor shall be substituted into the site data record whenever a valid 
hourly O3 concentration is not obtained from the primary 
monitor. In the event that hourly O3 concentration data are 
available for more than one secondary monitor, the hourly concentration 
values from the secondary monitors shall be averaged and substituted 
into the site data record.
    (c) In certain circumstances, including but not limited to site 
closures or relocations, data from two nearby sites may be combined into 
a single site data record for the purpose of calculating a valid design 
value. The appropriate Regional Administrator may approve such 
combinations after taking into consideration factors such as distance 
between sites, spatial and temporal patterns in air quality, local 
emissions and meteorology, jurisdictional boundaries, and terrain 
features.

             3. Data Reporting and Data Handling Conventions

    (a) Hourly average O3 concentrations shall be reported in 
parts per million (ppm) to the third decimal place, with additional 
digits to the right of the third decimal place truncated. Each hour 
shall be identified using local standard time (LST).
    (b) Moving 8-hour averages shall be computed from the hourly 
O3 concentration data for each hour of the year and shall be 
stored in the first, or start, hour of the 8-hour period. An 8-hour 
average shall be considered valid if at least 6 of the hourly 
concentrations for the 8-hour period are available. In the event that 
only 6 or 7 hourly concentrations are available, the 8-hour average 
shall be computed on the basis of the hours available, using 6 or 7, 
respectively, as the divisor. In addition, in the event that 5 or fewer 
hourly concentrations are available, the 8-hour average shall be 
considered valid if, after substituting zero for the missing hourly 
concentrations, the resulting 8-hour average is greater than the level 
of the NAAQS, or equivalently, if the sum of the available hourly 
concentrations is greater than 0.567 ppm. The 8-hour averages shall be 
reported to three decimal places, with additional digits to the right of 
the third decimal place truncated. Hourly O3 concentrations 
that have been approved under Sec. 50.14 as having been affected by 
exceptional events shall be counted as missing or unavailable in the 
calculation of 8-hour averages.
    (c) The daily maximum 8-hour average O3 concentration for 
a given day is the highest of the 17 consecutive 8-hour averages 
beginning with the 8-hour period from 7:00 a.m. to 3:00 p.m. and ending 
with the 8-hour period from 11:00 p.m. to 7:00 a.m. the following day 
(i.e., the 8-hour averages for 7:00 a.m. to 11:00 p.m.). Daily maximum 
8-hour average O3 concentrations shall be determined for each 
day with ambient O3 monitoring data, including days outside 
the O3 monitoring season if those data are available.

[[Page 168]]

    (d) A daily maximum 8-hour average O3 concentration shall 
be considered valid if valid 8-hour averages are available for at least 
13 of the 17 consecutive 8-hour periods starting from 7:00 a.m. to 11:00 
p.m. In addition, in the event that fewer than 13 valid 8-hour averages 
are available, a daily maximum 8-hour average O3 
concentration shall also be considered valid if it is greater than the 
level of the NAAQS. Hourly O3 concentrations that have been 
approved under Sec. 50.14 as having been affected by exceptional events 
shall be included when determining whether these criteria have been met.
    (e) The primary and secondary O3 design value statistic 
is the annual fourth-highest daily maximum 8-hour O3 
concentration, averaged over three years, expressed in ppm. The fourth-
highest daily maximum 8-hour O3 concentration for each year 
shall be determined based only on days meeting the validity criteria in 
3(d). The 3-year average shall be computed using the three most recent, 
consecutive years of ambient O3 monitoring data. Design 
values shall be reported in ppm to three decimal places, with additional 
digits to the right of the third decimal place truncated.

        4. Comparisons With the Primary and Secondary Ozone NAAQS

    (a) The primary and secondary national ambient air quality standards 
for O3 are met at an ambient air quality monitoring site when 
the 3-year average of the annual fourth-highest daily maximum 8-hour 
average O3 concentration (i.e., the design value) is less 
than or equal to 0.070 ppm.
    (b) A design value greater than the level of the NAAQS is always 
considered to be valid. A design value less than or equal to the level 
of the NAAQS must meet minimum data completeness requirements in order 
to be considered valid. These requirements are met for a 3-year period 
at a site if valid daily maximum 8-hour average O3 
concentrations are available for at least 90% of the days within the 
O3 monitoring season, on average, for the 3-year period, with 
a minimum of at least 75% of the days within the O3 
monitoring season in any one year.
    (c) When computing whether the minimum data completeness 
requirements have been met, meteorological or ambient data may be 
sufficient to demonstrate that meteorological conditions on missing days 
were not conducive to concentrations above the level of the NAAQS. 
Missing days assumed less than the level of the NAAQS are counted for 
the purpose of meeting the minimum data completeness requirements, 
subject to the approval of the appropriate Regional Administrator.
    (d) Comparisons with the primary and secondary O3 NAAQS 
are demonstrated by examples 1 and 2 as follows:

                                               Example 1--Site Meeting the Primary and Secondary O3 NAAQS
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Percent valid
                                                          days within O3    1st highest     2nd highest     3rd highest     4th highest     5th highest
                          Year                              monitoring     daily max 8-    daily max 8-    daily max 8-    daily max 8-    daily max 8-
                                                           season (Data    hour O3 (ppm)   hour O3 (ppm)   hour O3 (ppm)   hour O3 (ppm)   hour O3 (ppm)
                                                           completeness)
--------------------------------------------------------------------------------------------------------------------------------------------------------
2014....................................................             100           0.082           0.080           0.075           0.069           0.068
2015....................................................              96           0.074           0.073           0.065           0.062           0.060
2016....................................................              98           0.070           0.069           0.067           0.066           0.060
Average.................................................              98  ..............  ..............  ..............           0.065
--------------------------------------------------------------------------------------------------------------------------------------------------------

    As shown in Example 1, this site meets the primary and secondary 
O3 NAAQS because the 3-year average of the annual fourth-
highest daily maximum 8-hour average O3 concentrations (i.e., 
0.065666 ppm, truncated to 0.065 ppm) is less than or equal to 0.070 
ppm. The minimum data completeness requirements are also met (i.e., 
design value is considered valid) because the average percent of days 
within the O3 monitoring season with valid ambient monitoring 
data is greater than 90%, and no single year has less than 75% data 
completeness.

                                          Example 2--Site Failing to Meet the Primary and Secondary O3 O3 NAAQS
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Percent valid
                                                          days within O3    1st highest     2nd highest     3rd highest     4th highest     5th highest
                          Year                              monitoring     daily max 8-    daily max 8-    daily max 8-    daily max 8-    daily max 8-
                                                           season (Data    hour O3 (ppm)   hour O3 (ppm)   hour O3 (ppm)   hour O3 (ppm)   hour O3 (ppm)
                                                           completeness)
--------------------------------------------------------------------------------------------------------------------------------------------------------
2014....................................................              96           0.085           0.080           0.079           0.074           0.072
2015....................................................              74           0.084           0.083           0.072           0.071           0.068
2016....................................................              98           0.083           0.081           0.081           0.075           0.074
Average.................................................              89  ..............  ..............  ..............           0.073
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 169]]

    As shown in Example 2, this site fails to meet the primary and 
secondary O3 NAAQS because the 3-year average of the annual 
fourth-highest daily maximum 8-hour average O3 concentrations 
(i.e., 0.073333 ppm, truncated to 0.073 ppm) is greater than 0.070 ppm, 
even though the annual data completeness is less than 75% in one year 
and the 3-year average data completeness is less than 90% (i.e., design 
value would not otherwise be considered valid).

[80 FR 65458, Oct. 26, 2015]



PART 51_REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF 
IMPLEMENTATION PLANS--Table of Contents



             Subpart A_Air Emissions Reporting Requirements

               General Information For Inventory Preparers

Sec.
51.1 Who is responsible for actions described in this subpart?
51.5 What tools are available to help prepare and report emissions data?
51.10 [Reserved]

                     Specific Reporting Requirements

51.15 What data does my state need to report to EPA?
51.20 What are the emission thresholds that separate point and nonpoint 
          sources?
51.25 What geographic area must my state's inventory cover?
51.30 When does my state report which emissions data to EPA?
51.35 How can my state equalize the emission inventory effort from year 
          to year?
51.40 In what form and format should my state report the data to EPA?
51.45 Where should my state report the data?
51.50 What definitions apply to this subpart?

Appendix A to Subpart A of Part 51--Tables
Appendix B to Subpart A of Part 51 [Reserved]

Subparts B-E [Reserved]

                    Subpart F_Procedural Requirements

51.100 Definitions.
51.101 Stipulations.
51.102 Public hearings.
51.103 Submission of plans, preliminary review of plans.
51.104 Revisions.
51.105 Approval of plans.

                       Subpart G_Control Strategy

51.110 Attainment and maintenance of national standards.
51.111 Description of control measures.
51.112 Demonstration of adequacy.
51.113 [Reserved]
51.114 Emissions data and projections.
51.115 Air quality data and projections.
51.116 Data availability.
51.117 Additional provisions for lead.
51.118 Stack height provisions.
51.119 Intermittent control systems.
51.120 Requirements for State Implementation Plan revisions relating to 
          new motor vehicles.
51.121 Findings and requirements for submission of State implementation 
          plan revisions relating to emissions of nitrogen oxides.
51.122 Emissions reporting requirements for SIP revisions relating to 
          budgets for NOX emissions.
51.123 Findings and requirements for submission of State implementation 
          plan revisions relating to emissions of oxides of nitrogen 
          pursuant to the Clean Air Interstate Rule.
51.124 Findings and requirements for submission of State implementation 
          plan revisions relating to emissions of sulfur dioxide 
          pursuant to the Clean Air Interstate Rule.
51.125 [Reserved]
51.126 Determination of widespread use of ORVR and waiver of CAA section 
          182(b)(3) Stage II gasoline vapor recovery requirements.

        Subpart H_Prevention of Air Pollution Emergency Episodes

51.150 Classification of regions for episode plans.
51.151 Significant harm levels.
51.152 Contingency plans.
51.153 Reevaluation of episode plans.

            Subpart I_Review of New Sources and Modifications

51.160 Legally enforceable procedures.
51.161 Public availability of information.
51.162 Identification of responsible agency.
51.163 Administrative procedures.
51.164 Stack height procedures.
51.165 Permit requirements.
51.166 Prevention of significant deterioration of air quality.

               Subpart J_Ambient Air Quality Surveillance

51.190 Ambient air quality monitoring requirements.

[[Page 170]]

                      Subpart K_Source Surveillance

51.210 General.
51.211 Emission reports and recordkeeping.
51.212 Testing, inspection, enforcement, and complaints.
51.213 Transportation control measures.
51.214 Continuous emission monitoring.

                        Subpart L_Legal Authority

51.230 Requirements for all plans.
51.231 Identification of legal authority.
51.232 Assignment of legal authority to local agencies.

                Subpart M_Intergovernmental Consultation

                           Agency Designation

51.240 General plan requirements.
51.241 Nonattainment areas for carbon monoxide and ozone.
51.242 [Reserved]

                     Subpart N_Compliance Schedules

51.260 Legally enforceable compliance schedules.
51.261 Final compliance schedules.
51.262 Extension beyond one year.

            Subpart O_Miscellaneous Plan Content Requirements

51.280 Resources.
51.281 Copies of rules and regulations.
51.285 Public notification.
51.286 Electronic reporting.

                   Subpart P_Protection of Visibility

51.300 Purpose and applicability.
51.301 Definitions.
51.302 Reasonably attributable visibility impairment.
51.303 Exemptions from control.
51.304 Identification of integral vistas.
51.305 Monitoring for reasonably attributable visibility impairment.
51.306 [Reserved]
51.307 New source review.
51.308 Regional haze program requirements.
51.309 Requirements related to the Grand Canyon Visibility Transport 
          Commission.

                            Subpart Q_Reports

                       Air Quality Data Reporting

51.320 Annual air quality data report.

               Source Emissions and State Action Reporting

51.321 Annual source emissions and State action report.
51.322 Sources subject to emissions reporting.
51.323 Reportable emissions data and information.
51.324 Progress in plan enforcement.
51.326 Reportable revisions.
51.327 Enforcement orders and other State actions.
51.328 [Reserved]

                          Subpart R_Extensions

51.341 Request for 18-month extension.

          Subpart S_Inspection/Maintenance Program Requirements

51.350 Applicability.
51.351 Enhanced I/M performance standard.
51.352 Basic I/M performance standard.
51.353 Network type and program evaluation.
51.354 Adequate tools and resources.
51.355 Test frequency and convenience.
51.356 Vehicle coverage.
51.357 Test procedures and standards.
51.358 Test equipment.
51.359 Quality control.
51.360 Waivers and compliance via diagnostic inspection.
51.361 Motorist compliance enforcement.
51.362 Motorist compliance enforcement program oversight.
51.363 Quality assurance.
51.364 Enforcement against contractors, stations and inspectors.
51.365 Data collection.
51.366 Data analysis and reporting.
51.367 Inspector training and licensing or certification.
51.368 Public information and consumer protection.
51.369 Improving repair effectiveness.
51.370 Compliance with recall notices.
51.371 On-road testing.
51.372 State Implementation Plan submissions.
51.373 Implementation deadlines.

Appendix A to Subpart S of Part 51--Calibrations, Adjustments and 
          Quality Control
Appendix B to Subpart S of Part 51--Test Procedures
Appendix C to Subpart S of Part 51--Steady-State Short Test Standards
Appendix D to Subpart S of Part 51--Steady-State Short Test Equipment
Appendix E to Subpart S of Part 51--Transient Test Driving Cycle

    Subpart T_Conformity to State or Federal Implementation Plans of 
   Transportation Plans, Programs, and Projects Developed, Funded or 
       Approved Under Title 23 U.S.C. or the Federal Transit Laws

51.390 Implementation plan revision.

[[Page 171]]

                  Subpart U_Economic Incentive Programs

51.490 Applicability.
51.491 Definitions.
51.492 State program election and submittal.
51.493 State program requirements.
51.494 Use of program revenues.

Subpart W_Determining Conformity of General Federal Actions to State or 
                      Federal Implementation Plans

51.850 [Reserved]
51.851 State implementation plan (SIP) or Tribal implementation plan 
          (TIP) revision.
51.852-51.860 [Reserved]

Subpart X_Provisions for Implementation of 8-hour Ozone National Ambient 
                          Air Quality Standard

51.900 Definitions.
51.901 Applicability of part 51.
51.902 Which classification and nonattainment area planning provisions 
          of the CAA shall apply to areas designated nonattainment for 
          the 1997 8-hour NAAQS?
51.903 How do the classification and attainment date provisions in 
          section 181 of subpart 2 of the CAA apply to areas subject to 
          Sec. 51.902(a)?
51.904 How do the classification and attainment date provisions in 
          section 172(a) of subpart 1 of the CAA apply to areas subject 
          to Sec. 51.902(b)?
51.905 How do areas transition from the 1-hour NAAQS to the 1997 8-hour 
          NAAQS and what are the anti-backsliding provisions?
51.906 Redesignation to nonattainment following initial designations for 
          the 8-hour NAAQS.
51.907 For an area that fails to attain the 8-hour NAAQS by its 
          attainment date, how does EPA interpret sections 
          172(a)(2)(C)(ii) and 181(a)(5)(B) of the CAA?
51.908 What modeling and attainment demonstration requirements apply for 
          purposes of the 8-hour ozone NAAQS?
51.909 [Reserved]
51.910 What requirements for reasonable further progress (RFP) under 
          sections 172(c)(2) and 182 apply for areas designated 
          nonattainment for the 8-hour ozone NAAQS?
51.911 [Reserved]
51.912 What requirements apply for reasonably available control 
          technology (RACT) and reasonably available control measures 
          (RACM) under the 8-hour NAAQS?
51.913 How do the section 182(f) NOX exemption provisions 
          apply for the 8-hour NAAQS?
51.914 What new source review requirements apply for 8-hour ozone 
          nonattainment areas?
51.915 What emissions inventory requirements apply under the 8-hour 
          NAAQS?
51.916 What are the requirements for an Ozone Transport Region under the 
          8-hour NAAQS?
51.917 What is the effective date of designation for the Las Vegas, NV, 
          8-hour ozone nonattainment area?
51.918 Can any SIP planning requirements be suspended in 8-hour ozone 
          nonattainment areas that have air quality data that meets the 
          NAAQS?
51.919 Applicability.

                    Subpart Y_Mitigation Requirements

51.930 Mitigation of Exceptional Events.

  Subpart Z_Provisions for Implementation of PM2.5 National 
                      Ambient Air Quality Standards

51.1000 Definitions.
51.1001 Applicability of part 51.
51.1002 Classifications and reclassifications.
51.1003 Attainment plan due dates and submission requirements.
51.1004 Attainment dates.
51.1005 Attainment date extensions.
51.1006 Optional PM2.5 precursor demonstrations.
51.1007 [Reserved]
51.1008 Emissions inventory requirements.
51.1009 Moderate area attainment plan control strategy requirements.
51.1010 Serious area attainment plan control strategy requirements.
51.1011 Attainment demonstration and modeling requirements.
51.1012 Reasonable further progress (RFP) requirements.
51.1013 Quantitative milestone requirements.
51.1014 Contingency measures requirements.
51.1015 Clean data requirements.
51.1016 Continued applicability of the FIP and SIP requirements 
          pertaining to interstate transport under CAA section 
          110(a)(2)(D)(i) and (ii) after revocation of the 1997 primary 
          annual PM2.5 NAAQS.

  Subpart AA_Provisions for Implementation of the 2008 Ozone National 
                      Ambient Air Quality Standards

51.1100 Definitions.
51.1101 Applicability of part 51.
51.1102 Classification and nonattainment area planning provisions.
51.1103 Application of classification and attainment date provisions in 
          CAA section 181 to areas subject to Sec. 51.1102.
51.1104 [Reserved]

[[Page 172]]

51.1105 Transition from the 1997 ozone NAAQS to the 2008 ozone NAAQS and 
          anti-backsliding.
51.1106 Redesignation to nonattainment following initial designations.
51.1107 Determining eligibility for 1-year attainment date extensions 
          for the 2008 ozone NAAQS under CAA section 181(a)(5).
51.1108 Modeling and attainment demonstration requirements.
51.1109 [Reserved].
51.1110 Requirements for reasonable further progress (RFP).
51.1111 [Reserved].
51.1112 Requirements for reasonably available control technology (RACT) 
          and reasonably available control measures (RACM).
51.1113 Section 182(f) NOX exemption provisions.
51.1114 New source review requirements.
51.1115 Emissions inventory requirements.
51.1116 Requirements for an Ozone Transport Region.
51.1117 Fee programs for Severe and Extreme nonattainment areas that 
          fail to attain.
51.1118 Suspension of SIP planning requirements in nonattainment areas 
          that have air quality data that meet an ozone NAAQS.
51.1119 Applicability.

  Subpart BB_Data Requirements for Characterizing Air Quality for the 
                      Primary SO2 NAAQS

51.1200 Definitions.
51.1201 Purpose.
51.1202 Applicability.
51.1203 Air agency requirements.
51.1204 Enforceable emission limits providing for attainment.
51.1205 Ongoing data requirements.

  Subpart CC_Provisions for Implementation of the 2015 Ozone National 
                      Ambient Air Quality Standards

51.1300 Definitions.
51.1301 Applicability of this part.
51.1302 Classification and nonattainment area planning provisions.
51.1303 Application of classification and attainment date provisions in 
          CAA section 181 to areas subject to Sec. 51.1302.
51.1304-51.1305 [Reserved]
51.1306 Redesignation to nonattainment following initial designations.
51.1307 Determining eligibility for 1-year attainment date extensions 
          for an 8-hour ozone NAAQS under CAA section 181(a)(5).
51.1308 Modeling and attainment demonstration requirements.
51.1309 [Reserved]
51.1310 Requirements for reasonable further progress (RFP).
51.1311 [Reserved]
51.1312 Requirements for reasonably available control technology (RACT) 
          and reasonably available control measures (RACM).
51.1313 Section 182(f) NOX exemption provisions.
51.1314 New source review requirements.
51.1315 Emissions inventory requirements.
51.1316 Requirements for an Ozone Transport Region.
51.1317 Fee programs for Severe and Extreme nonattainment areas that 
          fail to attain.
51.1318 Suspension of SIP planning requirements in nonattainment areas 
          that have air quality data that meet an ozone NAAQS.
51.1319 [Reserved]

Appendixes A-K to Part 51 [Reserved]
Appendix L to Part 51--Example Regulations for Prevention of Air 
          Pollution Emergency Episodes
Appendix M to Part 51--Recommended Test Methods for State Implementation 
          Plans
Appendixes N-O to Part 51 [Reserved]
Appendix P to Part 51--Minimum Emission Monitoring Requirements
Appendixes Q-R to Part 51 [Reserved]
Appendix S to Part 51--Emission Offset Interpretative Ruling
Appendixes T-U to Part 51 [Reserved]
Appendix V to Part 51--Criteria for Determining the Completeness of Plan 
          Submissions
Appendix W to Part 51--Guideline on Air Quality Models
Appendix X to Part 51--Examples of Economic Incentive Programs
Appendix Y to Part 51--Guidelines for BART Determinations Under the 
          Regional Haze Rule

    Authority: 23 U.S.C. 101; 42 U.S.C. 7401-7671q.

    Source: 36 FR 22398, Nov. 25, 1971, unless otherwise noted.



             Subpart A_Air Emissions Reporting Requirements

    Source: 73 FR 76552, Dec. 17, 2008, unless otherwise noted.

               General Information for Inventory Preparers



Sec. 51.1  Who is responsible for actions described in this subpart?

    States must inventory emission sources located on nontribal lands 
and report this information to EPA.

[[Page 173]]



Sec. 51.5  What tools are available to help prepare and report
emissions data?

    (a) We urge your state to use estimation procedures described in 
documents from the Emission Inventory Improvement Program (EIIP), 
available at the following Internet address: http://www.epa.gov/ttn/
chief/eiip. These procedures are standardized and ranked according to 
relative uncertainty for each emission estimating technique. Using this 
guidance will enable others to use your state's data and evaluate its 
quality and consistency with other data.
    (b) Where current EIIP guidance materials have been supplanted by 
state-of-the-art emission estimation approaches or are not applicable to 
sources or source categories, states are urged to use applicable, state-
of-the-art techniques for estimating emissions.



Sec. 51.10  [Reserved]

                     Specific Reporting Requirements



Sec. 51.15  What data does my state need to report to EPA?

    (a) Pollutants. Report actual emissions of the following (see Sec. 
51.50 for precise definitions as required):
    (1) Required pollutants for triennial reports of annual (12-month) 
emissions for all sources and every-year reports of annual emissions 
from Type A sources:
    (i) Sulfur dioxide (SO2).
    (ii) Volatile organic compounds (VOC).
    (iii) Nitrogen oxides (NOX).
    (iv) Carbon monoxide (CO).
    (v) Lead and lead compounds.
    (vi) Primary PM2.5. As applicable, also report filterable 
and condensable components.
    (vii) Primary PM10. As applicable, also report filterable 
and condensable components.
    (viii) Ammonia (NH3).
    (2) A state may, at its option, choose to report NOX and 
VOC summer day emissions (or any other emissions) as required under the 
Ozone Implementation Rule or report CO winter work weekday emissions for 
CO nonattainment areas or CO attainment areas with maintenance plans to 
the Emission Inventory System (EIS) using the data elements described in 
this subpart.
    (3) A state may, at its option, choose to report ozone season day 
emissions of NOX as required under the NOX SIP 
Call and summer day emissions of NOX that may be required 
under the NOX SIP Call for controlled sources to the EIS 
using the data elements described in this subpart.
    (4) A state may, at its option, include estimates of emissions for 
additional pollutants (such as hazardous air pollutants) in its emission 
inventory reports.
    (b) Sources. Emissions should be reported from the following sources 
in all parts of the state, excluding sources located on tribal lands:
    (1) Point.
    (2) Nonpoint. States may choose to meet the requirements for some of 
their nonpoint sources by accepting the EPA's estimates for the sources 
for which the EPA makes calculations. In such instances, states are 
encouraged to review and update the activity values or other 
calculational inputs used by the EPA for these sources.
    (3) Onroad and Nonroad mobile. (i) Emissions for onroad and nonroad 
mobile sources must be reported as inputs to the latest EPA-developed 
mobile emissions models, such as the Motor Vehicle Emissions Simulator 
(MOVES) for onroad sources or the NMIM for nonroad sources. States using 
these models may report, at their discretion, emissions values computed 
from these models in addition to the model inputs.
    (ii) In lieu of submitting model inputs for onroad and nonroad 
mobile sources, California must submit emissions values.
    (iii) In lieu of submitting any data, states may accept existing EPA 
emission estimates.
    (4) Emissions for wild and prescribed fires are not required to be 
reported by states. If states wish to optionally report these sources, 
they must be reported to the events data category. The events data 
category is a day-specific accounting of these large-scale but usually 
short duration emissions. Submissions must include both daily emissions 
estimates as well as daily acres burned values. In lieu of submitting

[[Page 174]]

this information, states may accept the EPA estimates or they may submit 
inputs (e.g., acres burned, fuel loads) for us to use in the EPA's 
estimation approach.
    (c) Supporting information. You must report the data elements in 
Tables 2a and 2b in Appendix A of this subpart. We may ask you for other 
data on a voluntary basis to meet special purposes.
    (d) Confidential data. We do not consider the data in Tables 2a and 
2b in Appendix A of this subpart confidential, but some states limit 
release of these types of data. Any data that you submit to EPA under 
this subpart will be considered in the public domain and cannot be 
treated as confidential. If Federal and state requirements are 
inconsistent, consult your EPA Regional Office for a final 
reconciliation.

[73 FR 76552, Dec. 17, 2008, as amended at 80 FR 8795, Feb. 19, 2015]



Sec. 51.20  What are the emission thresholds that separate point and 
nonpoint sources?

    (a) All anthropogenic stationary sources must be included in your 
inventory as either point or nonpoint sources.
    (b) Sources that meet the definition of point source in this subpart 
must be reported as point sources. All pollutants specified in Sec. 
51.15(a) must be reported for point sources, not just the pollutant(s) 
that qualify the source as a point source.
    (c) If your state has lower emission reporting thresholds for point 
sources than paragraph (b) of this section, then you may use these in 
reporting your emissions to EPA.
    (d) All stationary source emissions that are not reported as point 
sources must be reported as nonpoint sources. Episodic wind-generated 
particulate matter (PM) emissions from sources that are not major 
sources may be excluded, for example dust lifted by high winds from 
natural or tilled soil. Emissions of nonpoint sources should be 
aggregated to the resolution required by the EIS as described in the 
current National Emission Inventory (NEI) inventory year plan posted at 
http://www.epa.gov/ttn/chief/eiinformation.html. In most cases, this is 
county level and must be separated and identified by source 
classification code (SCC). Nonpoint source categories or emission events 
reasonably estimated by the state to represent a de minimis percentage 
of total county and state emissions of a given pollutant may be omitted.
    (1) The reporting of wild and prescribed fires is encouraged but not 
required and should be done via only the ``Events'' data category.
    (2) Agricultural fires (also referred to as crop residue burning) 
must be reported to the nonpoint data category.

[73 FR 76552, Dec. 17, 2008, as amended at 80 FR 8795, Feb. 19, 2015]



Sec. 51.25  What geographic area must my state's inventory cover?

    Because of the regional nature of these pollutants, your state's 
inventory must be statewide, regardless of any area's attainment status.



Sec. 51.30  When does my state report which emissions data to EPA?

    All states are required to report two basic types of emission 
inventories to the EPA: An every-year inventory; and a triennial 
inventory.
    (a) Every-year inventory. See Tables 2a and 2b of Appendix A of this 
subpart for the specific data elements to report every year.
    (1) All states are required to report every year the annual (12-
month) emissions data described in Sec. 51.15 from Type A (large) point 
sources, as defined in Table 1 of Appendix A of this subpart. The first 
every-year cycle inventory will be for the 2009 inventory year and must 
be submitted to the EPA within 12 months, i.e., by December 31, 2010.
    (2) In inventory years that fall under the triennial inventory 
requirements, the reporting required by the triennial inventory 
satisfies the every-year reporting requirements of paragraph (a) of this 
section.
    (b) Triennial inventory. See Tables 2a and 2b to Appendix A of 
subpart A for the specific data elements that must be reported for the 
triennial inventories.

[[Page 175]]

    (1) All states are required to report for every third inventory year 
the annual (12-month) emissions data as described in Sec. 51.15. The 
first triennial inventory will be for the 2011 inventory and must be 
submitted to the EPA within 12 months, i.e., by December 31, 2012. 
Subsequent triennial inventories (2014, 2017, etc.) will be due 12 
months after the end of the inventory year, i.e., by December 31 of the 
following year.
    (2) [Reserved]

[80 FR 8796, Feb. 19, 2015]



Sec. 51.35  How can my state equalize the emission inventory effort
from year to year?

    (a) Compiling a triennial inventory means more effort every 3 years. 
As an option, your state may ease this workload spike by using the 
following approach:
    (1) Each year, collect and report data for all Type A (large) point 
sources (this is required for all Type A point sources).
    (2) Each year, collect data for one-third of your sources that are 
not Type A point sources. Collect data for a different third of these 
sources each year so that data has been collected for all of the sources 
that are not Type A point sources by the end of each 3-year cycle. You 
must save 3 years of data and then report all emissions from the sources 
that are not Type A point sources on the triennial inventory due date.
    (3) Each year, collect data for one-third of the nonpoint, nonroad 
mobile, and onroad mobile sources. You must save 3 years of data for 
each such source and then report all of these data on the triennial 
inventory due date.
    (b) For the sources described in paragraph (a) of this section, your 
state will have data from 3 successive years at any given time, rather 
than from the single year in which it is compiled.
    (c) If your state chooses the method of inventorying one-third of 
your sources that are not Type A point sources and triennial inventory 
nonpoint, nonroad mobile, and onroad mobile sources each year, your 
state must compile each year of the 3-year period identically. For 
example, if a process has not changed for a source category or 
individual plant, your state must use the same emission factors to 
calculate emissions for each year of the 3-year period. If your state 
has revised emission factors during the 3 years for a process that has 
not changed, you must compute previous years' data using the revised 
factor. If your state uses models to estimate emissions, you must make 
sure that the model is the same for all 3 years.

[80 FR 8796, Feb. 19, 2015]



Sec. 51.40  In what form and format should my state report the data
to EPA?

    You must report your emission inventory data to us in electronic 
form. We support specific electronic data reporting formats, and you are 
required to report your data in a format consistent with these. The term 
``format'' encompasses the definition of one or more specific data 
fields for each of the data elements listed in Tables 2a and 2b in 
Appendix A of this subpart; allowed code values for certain data fields; 
transmittal information; and data table relational structure. Because 
electronic reporting technology may change, contact the EPA Emission 
Inventory and Analysis Group (EIAG) for the latest specific formats. You 
can find information on the current formats at the following Internet 
address: http://www.epa.gov/ttn/chief/eis/2011nei/xml_data _eis.pdf. You 
may also call the air emissions contact in your EPA Regional Office or 
our Info CHIEF help desk at (919) 541-1000 or send email to 
[email protected].

[80 FR 8796, Feb. 19, 2015]



Sec. 51.45  Where should my state report the data?

    (a) Your state submits or reports data by providing it directly to 
EPA.
    (b) The latest information on data reporting procedures is available 
at the following Internet address: http://www.epa.gov/ttn/chief. You may 
also call our Info CHIEF help desk at (919) 541-1000 or e-mail to 
[email protected].



Sec. 51.50  What definitions apply to this subpart?

    Aircraft engine type means a code defining a unique combination of 
aircraft

[[Page 176]]

and engine used as an input parameter for calculating emissions from 
aircraft.
    Annual emissions means actual emissions for a plant, point, or 
process that are measured or calculated to represent a calendar year.
    Control measure means a unique code for the type of control device 
or operational measure (e.g., wet scrubber, flaring, process change, 
ban) used to reduce emissions.
    Emission calculation method means the code describing how the 
emissions for a pollutant were calculated, e.g., by stack test, 
continuous emissions monitor, EPA emission factor, etc.
    Emission factor means the ratio relating emissions of a specific 
pollutant to an activity throughput level.
    Emission operating type means the operational status of an emissions 
unit for the time period for which emissions are being reported, i.e., 
Routine, Startup, Shutdown, or Upset.
    Emission process identifier means a unique code for the process 
generating the emissions.
    Emission type means the type of emissions produced for onroad and 
nonroad sources or the mode of operation for marine vessels.
    Emissions year means the calendar year for which the emissions 
estimates are reported.
    Facility site identifier means the unique code for a plant or 
facility treated as a point source, containing one or more pollutant-
emitting units. The EPA's reporting format allows for state submittals 
to use either the state's data system identifiers or the EPA's Emission 
Inventory System identifiers.
    Facility site name means the name of the facility.
    Lead (Pb) means lead as defined in 40 CFR 50.12. Emissions of Pb 
which occur either as elemental Pb or as a chemical compound containing 
Pb should be reported as the mass of the Pb atoms only.
    Mobile source means a motor vehicle, nonroad engine or nonroad 
vehicle, where:
    (1) A motor vehicle is any self-propelled vehicle used to carry 
people or property on a street or highway;
    (2) A nonroad engine is an internal combustion engine (including 
fuel system) that is not used in a motor vehicle or a vehicle used 
solely for competition, or that is not affected by sections 111 or 202 
of the CAA; and
    (3) A nonroad vehicle is a vehicle that is run by a nonroad engine 
and that is not a motor vehicle or a vehicle used solely for 
competition.
    NAICS means North American Industry Classification System code. The 
NAICS codes are U.S. Department of Commerce's codes for categorizing 
businesses by products or services and have replaced Standard Industrial 
Classification codes.
    Nitrogen oxides (NOX) means nitrogen oxides (NOX) as 
defined in 40 CFR 60.2 as all oxides of nitrogen except N2O. 
Nitrogen oxides should be reported on an equivalent molecular weight 
basis as nitrogen dioxide (NO2).
    Nonpoint sources collectively represent individual sources that have 
not been inventoried as specific point or mobile sources. These 
individual sources treated collectively as nonpoint sources are 
typically too small, numerous, or difficult to inventory using the 
methods for the other classes of sources.
    Particulate matter (PM) is a criteria air pollutant. For the purpose 
of this subpart, the following definitions apply:
    (1) Filterable PM2.5 or Filterable PM10: Particles that are directly 
emitted by a source as a solid or liquid at stack or release conditions 
and captured on the filter of a stack test train. Filterable 
PM2.5 is particulate matter with an aerodynamic diameter 
equal to or less than 2.5 micrometers. Filterable PM10 is 
particulate matter with an aerodynamic diameter equal to or less than 10 
micrometers.
    (2) Condensable PM: Material that is vapor phase at stack 
conditions, but which condenses and/or reacts upon cooling and dilution 
in the ambient air to form solid or liquid PM immediately after 
discharge from the stack. Note that all condensable PM, if present from 
a source, is typically in the PM2.5 size fraction and, 
therefore, all of it is a component of both primary PM2.5 and 
primary PM10.
    (3) Primary PM2.5: The sum of filterable PM2.5 and 
condensable PM.

[[Page 177]]

    (4) Primary PM10: The sum of filterable PM10 
and condensable PM.
    (5) Secondary PM: Particles that form or grow in mass through 
chemical reactions in the ambient air well after dilution and 
condensation have occurred. Secondary PM is usually formed at some 
distance downwind from the source. Secondary PM should not be reported 
in the emission inventory and is not covered by this subpart.
    Percent control approach capture efficiency means the percentage of 
an exhaust gas stream actually collected for routing to a set of control 
devices.
    Percent control approach effectiveness means the percentage of time 
or activity throughput that a control approach is operating as designed, 
including the capture and reduction devices. This percentage accounts 
for the fact that controls typically are not 100 percent effective 
because of equipment downtime, upsets and decreases in control 
efficiencies.
    Percent control approach penetration means the percentage of a 
nonpoint source category activity that is covered by the reported 
control measures.
    Percent control measures reduction efficiency means the net emission 
reduction efficiency across all emissions control devices. It does not 
account for capture device efficiencies.
    Physical address means the location address (street address or other 
physical location description), locality name, state, and postal zip 
code of a facility. This is the physical location where the emissions 
occur; not the corporate headquarters or a mailing address.
    Point source means large, stationary (non-mobile), identifiable 
sources of emissions that release pollutants into the atmosphere. A 
point source is a facility that is a major source under 40 CFR part 70 
for one or more of the pollutants for which reporting is required by 
Sec. 51.15 (a)(1). This does not include the emissions of hazardous air 
pollutants, which are not considered in determining whether a source is 
a point source under this subpart. The minimum point source reporting 
thresholds are shown in Table 1 of Appendix A.
    Pollutant code means a unique code for each reported pollutant 
assigned by the reporting format specified by the EPA for each inventory 
year.
    Release point apportionment percent means the average percentage(s) 
of an emissions exhaust stream directed to a given release point.
    Release point exit gas flow rate means the numeric value of the flow 
rate of a stack gas.
    Release point exit gas temperature means the numeric value of the 
temperature of an exit gas stream in degrees Fahrenheit.
    Release point exit gas velocity means the numeric value of the 
velocity of an exit gas stream.
    Release point identifier means a unique code for the point where 
emissions from one or more processes release into the atmosphere.
    Release point stack diameter means the inner physical diameter of a 
stack.
    Release point stack height means physical height of a stack above 
the surrounding terrain.
    Release point type code means the code for physical configuration of 
the release point.
    Reporting period type means the code describing the time period 
covered by the emissions reported, i.e., Annual, 5-month ozone season, 
summer day, or winter.
    Source classification code (SCC) means a process-level code that 
describes the equipment and/or operation which is emitting pollutants.
    State and county FIPS code means the system of unique identifiers in 
the Federal Information Placement System (FIPS) used to identify states, 
counties and parishes for the entire United States, Puerto Rico, and 
Guam.
    Throughput means a measurable factor or parameter that relates 
directly or indirectly to the emissions of an air pollution source 
during the period for which emissions are reported. Depending on the 
type of source category, activity information may refer to the amount of 
fuel combusted, raw material processed, product manufactured, or 
material handled or processed. It may also refer to population, 
employment, or number of units. Activity throughput is typically the 
value that is multiplied against an emission factor to generate an 
emissions estimate.

[[Page 178]]

    Type A source means large point sources with a potential to emit 
greater than or equal to any of the thresholds listed in Table 1 of 
Appendix A of this subpart. If a source is a Type A source for any 
pollutant listed in Table 1, then the emissions for all pollutants 
required by Sec. 51.15 must be reported for that source.
    Unit design capacity means a measure of the size of a point source, 
based on the reported maximum continuous throughput or output capacity 
of the unit.
    Unit identifier means a unique code for the unit that generates 
emissions, typically a physical piece of equipment or a closely related 
set of equipment.
    VOC means volatile organic compounds. The EPA's regulatory 
definition of VOC is in 40 CFR 51.100.

[80 FR 8796, Feb. 19, 2015]



             Sec. Appendix A to Subpart A of Part 51--Tables

 Table 1 to Appendix A of Subpart A--Emission Thresholds \1\ by Pollutant for Treatment as Point Source Under 40
                                                    CFR 51.30
----------------------------------------------------------------------------------------------------------------
                                            Every-year                           Triennial
                                         -----------------------------------------------------------------------
                Pollutant                 Type A sources
                                                \2\             Type B sources              NAA sources \3\
----------------------------------------------------------------------------------------------------------------
(1) SO2.................................  =25  =100...........  =100.
                                                      00
                                          ..............  ..........................  PM2.5 (Serious) >=70.
(2) VOC.................................  =25  =100...........  =100.
                                                       0
                                          ..............  within OTR \4\ =50.
                                                           eq>=50.
                                          ..............  ..........................  O3 (Serious) >=50.
                                          ..............  ..........................  O3 (Severe) >=25.
                                          ..............  ..........................  O3 (Extreme) >=10.
                                          ..............  ..........................  PM2.5 (Serious) >=70.
(3) NOX.................................  =25  =100...........  =100.
                                                      00
                                          ..............  ..........................  O3 (Serious) >=50.
                                          ..............  ..........................  O3 (Severe) >=25.
                                          ..............  ..........................  O3 (Extreme) >=10.
                                          ..............  ..........................  PM2.5 (Serious) >=70.
(4) CO..................................  =25  =1000..........  =1000.
                                                      00
                                          ..............  ..........................  CO (all areas) =100.
(5) Lead................................  ..............  =0.5 (actual)..  =0.5 (actual).
(6) Primary PM10........................  =25  =100...........  =100.
                                                       0
                                          ..............  ..........................  PM10 (Serious) >=70.
(7) Primary PM2.5.......................  =25  =100...........  =100.
                                                       0
                                          ..............  ..........................  PM2.5 (Serious) >=70.
(8) NH3.................................  =25  =100...........  =100.
                                                       0
                                          ..............  ..........................  PM2.5 (Serious) >=70.
----------------------------------------------------------------------------------------------------------------
\1\ Thresholds for point source determination shown in tons per year of potential to emit as defined in 40 CFR
  part 70, with the exception of lead. Reported emissions should be in actual tons emitted for the required time
  period.
\2\ Type A sources are a subset of the Type B sources and are the larger emitting sources by pollutant.
\3\ NAA = Nonattainment Area. The point source reporting thresholds vary by attainment status for SO2, VOC, NOX,
  CO, PM10, PM2.5, and NH3.
\4\ OTR = Ozone Transport Region (see 40 CFR 51.1300(k)).


    Table 2a to Appendix A of Subpart A--Facility Inventory \1\ Data
 Elements for Reporting Emissions From Point Sources, Where Required by
                              40 CFR 51.30
------------------------------------------------------------------------
                              Data elements
-------------------------------------------------------------------------
(1) Emissions Year.
(2) State and County FIPS Code or Tribal Code.
(3) Facility Site Identifier.
(4) Unit Identifier.
(5) Emission Process Identifier.
(6) Release Point Identifier.
(7) Facility Site Name.
(8) Physical Address (Location Address, Locality Name, State and Postal
 Code).
(9) Latitude and Longitude at facility level.
(10) Source Classification Code.
(11) Aircraft Engine Type (where applicable).
(12) Facility Site Status and Year.
(13) Release Point Stack Height and Unit of Measure.
(14) Release Point Stack Diameter and Unit of Measure.
(15) Release Point Exit Gas Temperature and Unit of Measure.
(16) Release Point Exit Gas Velocity or Release Point Exit Gas Flow Rate
 and Unit of Measure.
(17) Release Point Status and Year.
(18) NAICS at facility level.
(19) Unit Design Capacity and Unit of Measure (for some unit types).
(20) Unit Type.
(21) Unit Status and Year.

[[Page 179]]

 
(22) Release Point Apportionment Percent.
(23) Release Point Type.
(24) Control Measure and Control Pollutant (where applicable).
(25) Percent Control Approach Capture Efficiency (where applicable).
(26) Percent Control Measures Reduction Efficiency (where applicable).
(27) Percent Control Approach Effectiveness (where applicable).
------------------------------------------------------------------------
\1\ Facility Inventory data elements need only be reported once to the
  EIS and then revised if needed. They do not need to be reported for
  each triennial or every-year emissions inventory.


 Table 2b to Appendix A of Subpart A--Data Elements for Reporting Emissions From Point, Nonpoint, Onroad Mobile
                           and Nonroad Mobile Sources, Where Required by 40 CFR 51.30
----------------------------------------------------------------------------------------------------------------
                      Data elements                           Point       Nonpoint       Onroad        Nonroad
----------------------------------------------------------------------------------------------------------------
(1) Emissions Year......................................            Y             Y             Y             Y
(2) FIPS code...........................................            Y             Y             Y             Y
(3) Shape Identifiers (where applicable)................  ............            Y
(4) Source Classification Code..........................  ............            Y             Y             Y
(5) Emission Type (where applicable)....................  ............            Y             Y             Y
(8) Emission Factor.....................................            Y             Y
(9) Throughput (Value, Material, Unit of Measure, and               Y             Y             Y
 Type)..................................................
(10) Pollutant Code.....................................            Y             Y             Y             Y
(11) Annual Emissions and Unit of Measure...............            Y             Y             Y             Y
(12) Reporting Period Type (Annual).....................            Y             Y             Y             Y
(13) Emission Operating Type (Routine)..................            Y   ............
(14) Emission Calculation Method........................            Y             Y
(15) Control Measure and Control Pollutant (where         ............            Y
 applicable)............................................
(16) Percent Control Measures Reduction Efficiency        ............            Y
 (where applicable).....................................
(17) Percent Control Approach Effectiveness (where        ............            Y
 applicable)............................................
(18) Percent Control Approach Penetration (where          ............            Y   ............  ............
 applicable)............................................
----------------------------------------------------------------------------------------------------------------


[73 FR 76552, Dec. 17, 2008, as amended at 80 FR 8796, Feb. 19, 2015; 81 
FR 58149, Aug. 24, 2016; 83 FR 63031, Dec. 6, 2018]

Subparts B-E [Reserved]



                    Subpart F_Procedural Requirements

    Authority: 42 U.S.C. 7401, 7411, 7412, 7413, 7414, 7470-7479, 7501-
7508, 7601, and 7602.



Sec. 51.100  Definitions.

    As used in this part, all terms not defined herein will have the 
meaning given them in the Act:
    (a) Act means the Clean Air Act (42 U.S.C. 7401 et seq., as amended 
by Pub. L. 91-604, 84 Stat. 1676 Pub. L. 95-95, 91 Stat., 685 and Pub. 
L. 95-190, 91 Stat., 1399.)
    (b) Administrator means the Administrator of the Environmental 
Protection Agency (EPA) or an authorized representative.
    (c) Primary standard means a national primary ambient air quality 
standard promulgated pursuant to section 109 of the Act.
    (d) Secondary standard means a national secondary ambient air 
quality standard promulgated pursuant to section 109 of the Act.
    (e) National standard means either a primary or secondary standard.
    (f) Owner or operator means any person who owns, leases, operates, 
controls, or supervises a facility, building, structure, or installation 
which directly or indirectly result or may result in emissions of any 
air pollutant for which a national standard is in effect.
    (g) Local agency means any local government agency other than the 
State

[[Page 180]]

agency, which is charged with responsibility for carrying out a portion 
of the plan.
    (h) Regional Office means one of the ten (10) EPA Regional Offices.
    (i) State agency means the air pollution control agency primarily 
responsible for development and implementation of a plan under the Act.
    (j) Plan means an implementation plan approved or promulgated under 
section 110 of 172 of the Act.
    (k) Point source means the following:
    (1) For particulate matter, sulfur oxides, carbon monoxide, volatile 
organic compounds (VOC) and nitrogen dioxide--
    (i) Any stationary source the actual emissions of which are in 
excess of 90.7 metric tons (100 tons) per year of the pollutant in a 
region containing an area whose 1980 urban place population, as defined 
by the U.S. Bureau of the Census, was equal to or greater than 1 
million.
    (ii) Any stationary source the actual emissions of which are in 
excess of 22.7 metric tons (25 tons) per year of the pollutant in a 
region containing an area whose 1980 urban place population, as defined 
by the U.S. Bureau of the Census, was less than 1 million; or
    (2) For lead or lead compounds measured as elemental lead, any 
stationary source that actually emits a total of 4.5 metric tons (5 
tons) per year or more.
    (l) Area source means any small residential, governmental, 
institutional, commercial, or industrial fuel combustion operations; 
onsite solid waste disposal facility; motor vehicles, aircraft vessels, 
or other transportation facilities or other miscellaneous sources 
identified through inventory techniques similar to those described in 
the ``AEROS Manual series, Vol. II AEROS User's Manual,'' EPA-450/2-76-
029 December 1976.
    (m) Region means an area designated as an air quality control region 
(AQCR) under section 107(c) of the Act.
    (n) Control strategy means a combination of measures designated to 
achieve the aggregate reduction of emissions necessary for attainment 
and maintenance of national standards including, but not limited to, 
measures such as:
    (1) Emission limitations.
    (2) Federal or State emission charges or taxes or other economic 
incentives or disincentives.
    (3) Closing or relocation of residential, commercial, or industrial 
facilities.
    (4) Changes in schedules or methods of operation of commercial or 
industrial facilities or transportation systems, including, but not 
limited to, short-term changes made in accordance with standby plans.
    (5) Periodic inspection and testing of motor vehicle emission 
control systems, at such time as the Administrator determines that such 
programs are feasible and practicable.
    (6) Emission control measures applicable to in-use motor vehicles, 
including, but not limited to, measures such as mandatory maintenance, 
installation of emission control devices, and conversion to gaseous 
fuels.
    (7) Any transportation control measure including those 
transportation measures listed in section 108(f) of the Clean Air Act as 
amended.
    (8) Any variation of, or alternative to any measure delineated 
herein.
    (9) Control or prohibition of a fuel or fuel additive used in motor 
vehicles, if such control or prohibition is necessary to achieve a 
national primary or secondary air quality standard and is approved by 
the Administrator under section 211(c)(4)(C) of the Act.
    (o) Reasonably available control technology (RACT) means devices, 
systems, process modifications, or other apparatus or techniques that 
are reasonably available taking into account:
    (1) The necessity of imposing such controls in order to attain and 
maintain a national ambient air quality standard;
    (2) The social, environmental, and economic impact of such controls; 
and
    (3) Alternative means of providing for attainment and maintenance of 
such standard. (This provision defines RACT for the purposes of Sec. 
51.341(b) only.)
    (p) Compliance schedule means the date or dates by which a source or 
category of sources is required to comply with specific emission 
limitations contained in an implementation plan and with any increments 
of progress toward such compliance.

[[Page 181]]

    (q) Increments of progress means steps toward compliance which will 
be taken by a specific source, including:
    (1) Date of submittal of the source's final control plan to the 
appropriate air pollution control agency;
    (2) Date by which contracts for emission control systems or process 
modifications will be awarded; or date by which orders will be issued 
for the purchase of component parts to accomplish emission control or 
process modification;
    (3) Date of initiation of on-site construction or installation of 
emission control equipment or process change;
    (4) Date by which on-site construction or installation of emission 
control equipment or process modification is to be completed; and
    (5) Date by which final compliance is to be achieved.
    (r) Transportation control measure means any measure that is 
directed toward reducing emissions of air pollutants from transportation 
sources. Such measures include, but are not limited to, those listed in 
section 108(f) of the Clean Air Act.
    (s) Volatile organic compounds (VOC) means any compound of carbon, 
excluding carbon monoxide, carbon dioxide, carbonic acid, metallic 
carbides or carbonates, and ammonium carbonate, which participates in 
atmospheric photochemical reactions.
    (1) This includes any such organic compound other than the 
following, which have been determined to have negligible photochemical 
reactivity: Methane; ethane; methylene chloride (dichloromethane); 
1,1,1-trichloroethane (methyl chloroform); 1,1,2-trichloro-1,2,2-
trifluoroethane (CFC-113); trichlorofluoromethane (CFC-11); 
dichlorodifluoromethane (CFC-12); chlorodifluoromethane (HCFC-22); 
trifluoromethane (HFC-23); 1,2-dichloro 1,1,2,2-tetrafluoroethane (CFC-
114); chloropentafluoroethane (CFC-115); 1,1,1-trifluoro 2,2-
dichloroethane (HCFC-123); 1,1,1,2-tetrafluoroethane (HFC-134a); 1,1-
dichloro 1-fluoroethane (HCFC-141b); 1-chloro 1,1-difluoroethane (HCFC-
142b); 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124); pentafluoroethane 
(HFC-125); 1,1,2,2-tetrafluoroethane (HFC-134); 1,1,1-trifluoroethane 
(HFC-143a); 1,1-difluoroethane (HFC-152a); parachlorobenzotrifluoride 
(PCBTF); cyclic, branched, or linear completely methylated siloxanes; 
acetone; perchloroethylene (tetrachloroethylene); 3,3-dichloro-
1,1,1,2,2-pentafluoropropane (HCFC-225ca); 1,3-dichloro-1,1,2,2,3-
pentafluoropropane (HCFC-225cb); 1,1,1,2,3,4,4,5,5,5-decafluoropentane 
(HFC 43-10mee); difluoromethane (HFC-32); ethylfluoride (HFC-161); 
1,1,1,3,3,3-hexafluoropropane (HFC-236fa); 1,1,2,2,3-pentafluoropropane 
(HFC-245ca); 1,1,2,3,3-pentafluoropropane (HFC-245ea); 1,1,1,2,3-
pentafluoropropane (HFC-245eb); 1,1,1,3,3-pentafluoropropane (HFC-
245fa); 1,1,1,2,3,3-hexafluoropropane (HFC-236ea); 1,1,1,3,3-
pentafluorobutane (HFC-365mfc); chlorofluoromethane (HCFC-31); 1 chloro-
1-fluoroethane (HCFC-151a); 1,2-dichloro-1,1,2-trifluoroethane (HCFC-
123a); 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane 
(C4F9OCH3 or HFE-7100); 2-
(difluoromethoxymethyl)-1,1,1,2,3,3,3-heptafluoropropane 
((CF3)2CFCF2OCH3); 1-ethoxy-
1,1,2,2,3,3,4,4,4-nonafluorobutane 
(C4F9OC2H5 or HFE-7200); 2-
(ethoxydifluoromethyl)-1,1,1,2,3,3,3-heptafluoropropane 
((CF3)2CFCF2OC2H5)
; methyl acetate; 1,1,1,2,2,3,3-heptafluoro-3-methoxy-propane (n-
C3F7OCH3, HFE-7000); 3-ethoxy- 1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-
(trifluoromethyl) hexane (HFE-7500); 1,1,1,2,3,3,3-heptafluoropropane 
(HFC 227ea); methyl formate (HCOOCH3); 1,1,1,2,2,3,4,5,5,5-decafluoro-3-
methoxy-4-trifluoromethyl-pentane (HFE-7300); propylene carbonate; 
dimethyl carbonate; trans-1,3,3,3-tetrafluoropropene; 
HCF2OCF2H (HFE-134); 
HCF2OCF2OCF2H (HFE-236cal2); 
HCF2OCF2CF2OCF2H (HFE-
338pcc13); 
HCF2OCF2OCF2CF2OCF2
H (H-Galden 1040x or H-Galden ZT 130 (or 150 or 180)); trans 1-chloro-
3,3,3-trifluoroprop-1-ene; 2,3,3,3-tetrafluoropropene; 2-amino-2-methyl-
1-propanol; t-butyl acetate; 1,1,2,2- Tetrafluoro -1-(2,2,2-
trifluoroethoxy) ethane; cis-1,1,1,4,4,4-hexafluorobut-2-ene (HFO-
1336mzz-Z); and perfluorocarbon compounds which fall into these classes:

[[Page 182]]

    (i) Cyclic, branched, or linear, completely fluorinated alkanes;
    (ii) Cyclic, branched, or linear, completely fluorinated ethers with 
no unsaturations;
    (iii) Cyclic, branched, or linear, completely fluorinated tertiary 
amines with no unsaturations; and
    (iv) Sulfur containing perfluorocarbons with no unsaturations and 
with sulfur bonds only to carbon and fluorine.
    (2) For purposes of determining compliance with emissions limits, 
VOC will be measured by the test methods in the approved State 
implementation plan (SIP) or 40 CFR part 60, appendix A, as applicable. 
Where such a method also measures compounds with negligible 
photochemical reactivity, these negligibility-reactive compounds may be 
excluded as VOC if the amount of such compounds is accurately 
quantified, and such exclusion is approved by the enforcement authority.
    (3) As a precondition to excluding these compounds as VOC or at any 
time thereafter, the enforcement authority may require an owner or 
operator to provide monitoring or testing methods and results 
demonstrating, to the satisfaction of the enforcement authority, the 
amount of negligibly-reactive compounds in the source's emissions.
    (4) For purposes of Federal enforcement for a specific source, the 
EPA shall use the test methods specified in the applicable EPA-approved 
SIP, in a permit issued pursuant to a program approved or promulgated 
under title V of the Act, or under 40 CFR part 51, subpart I or appendix 
S, or under 40 CFR parts 52 or 60. The EPA shall not be bound by any 
State determination as to appropriate methods for testing or monitoring 
negligibly-reactive compounds if such determination is not reflected in 
any of the above provisions.
    (5) [Reserved]
    (6) For the purposes of determining compliance with California's 
aerosol coatings reactivity-based regulation, (as described in the 
California Code of Regulations, Title 17, Division 3, Chapter 1, 
Subchapter 8.5, Article 3), any organic compound in the volatile portion 
of an aerosol coating is counted towards that product's reactivity-based 
limit. Therefore, the compounds identified in paragraph (s) of this 
section as negligibly reactive and excluded from EPA's definition of 
VOCs are to be counted towards a product's reactivity limit for the 
purposes of determining compliance with California's aerosol coatings 
reactivity-based regulation.
    (7) For the purposes of determining compliance with EPA's aerosol 
coatings reactivity based regulation (as described in 40 CFR part 59--
National Volatile Organic Compound Emission Standards for Consumer and 
Commercial Products) any organic compound in the volatile portion of an 
aerosol coating is counted towards the product's reactivity-based limit, 
as provided in 40 CFR part 59, subpart E. Therefore, the compounds that 
are used in aerosol coating products and that are identified in 
paragraphs (s)(1) or (s)(5) of this section as excluded from EPA's 
definition of VOC are to be counted towards a product's reactivity limit 
for the purposes of determining compliance with EPA's aerosol coatings 
reactivity-based national regulation, as provided in 40 CFR part 59, 
subpart E.
    (t)-(w) [Reserved]
    (x) Time period means any period of time designated by hour, month, 
season, calendar year, averaging time, or other suitable 
characteristics, for which ambient air quality is estimated.
    (y) Variance means the temporary deferral of a final compliance date 
for an individual source subject to an approved regulation, or a 
temporary change to an approved regulation as it applies to an 
individual source.
    (z) Emission limitation and emission standard mean a requirement 
established by a State, local government, or the Administrator which 
limits the quantity, rate, or concentration of emissions of air 
pollutants on a continuous basis, including any requirements which limit 
the level of opacity, prescribe equipment, set fuel specifications, or 
prescribe operation or maintenance procedures for a source to assure 
continuous emission reduction.
    (aa) Capacity factor means the ratio of the average load on a 
machine or equipment for the period of time considered to the capacity 
rating of the machine or equipment.

[[Page 183]]

    (bb) Excess emissions means emissions of an air pollutant in excess 
of an emission standard.
    (cc) Nitric acid plant means any facility producing nitric acid 30 
to 70 percent in strength by either the pressure or atmospheric pressure 
process.
    (dd) Sulfuric acid plant means any facility producing sulfuric acid 
by the contact process by burning elemental sulfur, alkylation acid, 
hydrogen sulfide, or acid sludge, but does not include facilities where 
conversion to sulfuric acid is utilized primarily as a means of 
preventing emissions to the atmosphere of sulfur dioxide or other sulfur 
compounds.
    (ee) Fossil fuel-fired steam generator means a furnance or bioler 
used in the process of burning fossil fuel for the primary purpose of 
producing steam by heat transfer.
    (ff) Stack means any point in a source designed to emit solids, 
liquids, or gases into the air, including a pipe or duct but not 
including flares.
    (gg) A stack in existence means that the owner or operator had (1) 
begun, or caused to begin, a continuous program of physical on-site 
construction of the stack or (2) entered into binding agreements or 
contractual obligations, which could not be cancelled or modified 
without substantial loss to the owner or operator, to undertake a 
program of construction of the stack to be completed within a reasonable 
time.
    (hh)(1) Dispersion technique means any technique which attempts to 
affect the concentration of a pollutant in the ambient air by:
    (i) Using that portion of a stack which exceeds good engineering 
practice stack height:
    (ii) Varying the rate of emission of a pollutant according to 
atmospheric conditions or ambient concentrations of that pollutant; or
    (iii) Increasing final exhaust gas plume rise by manipulating source 
process parameters, exhaust gas parameters, stack parameters, or 
combining exhaust gases from several existing stacks into one stack; or 
other selective handling of exhaust gas streams so as to increase the 
exhaust gas plume rise.
    (2) The preceding sentence does not include:
    (i) The reheating of a gas stream, following use of a pollution 
control system, for the purpose of returning the gas to the temperature 
at which it was originally discharged from the facility generating the 
gas stream;
    (ii) The merging of exhaust gas streams where:
    (A) The source owner or operator demonstrates that the facility was 
originally designed and constructed with such merged gas streams;
    (B) After July 8, 1985 such merging is part of a change in operation 
at the facility that includes the installation of pollution controls and 
is accompanied by a net reduction in the allowable emissions of a 
pollutant. This exclusion from the definition of dispersion techniques 
shall apply only to the emission limitation for the pollutant affected 
by such change in operation; or
    (C) Before July 8, 1985, such merging was part of a change in 
operation at the facility that included the installation of emissions 
control equipment or was carried out for sound economic or engineering 
reasons. Where there was an increase in the emission limitation or, in 
the event that no emission limitation was in existence prior to the 
merging, an increase in the quantity of pollutants actually emitted 
prior to the merging, the reviewing agency shall presume that merging 
was significantly motivated by an intent to gain emissions credit for 
greater dispersion. Absent a demonstration by the source owner or 
operator that merging was not significantly motivated by such intent, 
the reviewing agency shall deny credit for the effects of such merging 
in calculating the allowable emissions for the source;
    (iii) Smoke management in agricultural or silvicultural prescribed 
burning programs;
    (iv) Episodic restrictions on residential woodburning and open 
burning; or
    (v) Techniques under Sec. 51.100(hh)(1)(iii) which increase final 
exhaust gas plume rise where the resulting allowable emissions of sulfur 
dioxide from the facility do not exceed 5,000 tons per year.
    (ii) Good engineering practice (GEP) stack height means the greater 
of:

[[Page 184]]

    (1) 65 meters, measured from the ground-level elevation at the base 
of the stack:
    (2)(i) For stacks in existence on January 12, 1979, and for which 
the owner or operator had obtained all applicable permits or approvals 
required under 40 CFR parts 51 and 52.

Hg = 2.5H,


provided the owner or operator produces evidence that this equation was 
actually relied on in establishing an emission limitation:
    (ii) For all other stacks,

Hg = H + 1.5L

where:

Hg = good engineering practice stack height, measured from 
          the ground-level elevation at the base of the stack,
H = height of nearby structure(s) measured from the ground-level 
          elevation at the base of the stack.
L = lesser dimension, height or projected width, of nearby structure(s)


provided that the EPA, State or local control agency may require the use 
of a field study or fluid model to verify GEP stack height for the 
source; or
    (3) The height demonstrated by a fluid model or a field study 
approved by the EPA State or local control agency, which ensures that 
the emissions from a stack do not result in excessive concentrations of 
any air pollutant as a result of atmospheric downwash, wakes, or eddy 
effects created by the source itself, nearby structures or nearby 
terrain features.
    (jj) Nearby as used in Sec. 51.100(ii) of this part is defined for 
a specific structure or terrain feature and
    (1) For purposes of applying the formulae provided in Sec. 
51.100(ii)(2) means that distance up to five times the lesser of the 
height or the width dimension of a structure, but not greater than 0.8 
km (\1/2\ mile), and
    (2) For conducting demonstrations under Sec. 51.100(ii)(3) means 
not greater than 0.8 km (\1/2\ mile), except that the portion of a 
terrain feature may be considered to be nearby which falls within a 
distance of up to 10 times the maximum height (Ht) of the 
feature, not to exceed 2 miles if such feature achieves a height 
(Ht) 0.8 km from the stack that is at least 40 percent of the 
GEP stack height determined by the formulae provided in Sec. 
51.100(ii)(2)(ii) of this part or 26 meters, whichever is greater, as 
measured from the ground-level elevation at the base of the stack. The 
height of the structure or terrain feature is measured from the ground-
level elevation at the base of the stack.
    (kk) Excessive concentration is defined for the purpose of 
determining good engineering practice stack height under Sec. 
51.100(ii)(3) and means:
    (1) For sources seeking credit for stack height exceeding that 
established under Sec. 51.100(ii)(2) a maximum ground-level 
concentration due to emissions from a stack due in whole or part to 
downwash, wakes, and eddy effects produced by nearby structures or 
nearby terrain features which individually is at least 40 percent in 
excess of the maximum concentration experienced in the absence of such 
downwash, wakes, or eddy effects and which contributes to a total 
concentration due to emissions from all sources that is greater than an 
ambient air quality standard. For sources subject to the prevention of 
significant deterioration program (40 CFR 51.166 and 52.21), an 
excessive concentration alternatively means a maximum ground-level 
concentration due to emissions from a stack due in whole or part to 
downwash, wakes, or eddy effects produced by nearby structures or nearby 
terrain features which individually is at least 40 percent in excess of 
the maximum concentration experienced in the absence of such downwash, 
wakes, or eddy effects and greater than a prevention of significant 
deterioration increment. The allowable emission rate to be used in 
making demonstrations under this part shall be prescribed by the new 
source performance standard that is applicable to the source category 
unless the owner or operator demonstrates that this emission rate is 
infeasible. Where such demonstrations are approved by the authority 
administering the State implementation plan, an alternative emission 
rate shall be established in consultation with the source owner or 
operator.

[[Page 185]]

    (2) For sources seeking credit after October 11, 1983, for increases 
in existing stack heights up to the heights established under Sec. 
51.100(ii)(2), either (i) a maximum ground-level concentration due in 
whole or part to downwash, wakes or eddy effects as provided in 
paragraph (kk)(1) of this section, except that the emission rate 
specified by any applicable State implementation plan (or, in the 
absence of such a limit, the actual emission rate) shall be used, or 
(ii) the actual presence of a local nuisance caused by the existing 
stack, as determined by the authority administering the State 
implementation plan; and
    (3) For sources seeking credit after January 12, 1979 for a stack 
height determined under Sec. 51.100(ii)(2) where the authority 
administering the State implementation plan requires the use of a field 
study or fluid model to verify GEP stack height, for sources seeking 
stack height credit after November 9, 1984 based on the aerodynamic 
influence of cooling towers, and for sources seeking stack height credit 
after December 31, 1970 based on the aerodynamic influence of structures 
not adequately represented by the equations in Sec. 51.100(ii)(2), a 
maximum ground-level concentration due in whole or part to downwash, 
wakes or eddy effects that is at least 40 percent in excess of the 
maximum concentration experienced in the absence of such downwash, 
wakes, or eddy effects.
    (ll)-(mm) [Reserved]
    (nn) Intermittent control system (ICS) means a dispersion technique 
which varies the rate at which pollutants are emitted to the atmosphere 
according to meteorological conditions and/or ambient concentrations of 
the pollutant, in order to prevent ground-level concentrations in excess 
of applicable ambient air quality standards. Such a dispersion technique 
is an ICS whether used alone, used with other dispersion techniques, or 
used as a supplement to continuous emission controls (i.e., used as a 
supplemental control system).
    (oo) Particulate matter means any airborne finely divided solid or 
liquid material with an aerodynamic diameter smaller than 100 
micrometers.
    (pp) Particulate matter emissions means all finely divided solid or 
liquid material, other than uncombined water, emitted to the ambient air 
as measured by applicable reference methods, or an equivalent or 
alternative method, specified in this chapter, or by a test method 
specified in an approved State implementation plan.
    (qq) PM10 means particulate matter with an aerodynamic 
diameter less than or equal to a nominal 10 micrometers as measured by a 
reference method based on appendix J of part 50 of this chapter and 
designated in accordance with part 53 of this chapter or by an 
equivalent method designated in accordance with part 53 of this chapter.
    (rr) PM10 emissions means finely divided solid or liquid 
material, with an aerodynamic diameter less than or equal to a nominal 
10 micrometers emitted to the ambient air as measured by an applicable 
reference method, or an equivalent or alternative method, specified in 
this chapter or by a test method specified in an approved State 
implementation plan.
    (ss) Total suspended particulate means particulate matter as 
measured by the method described in appendix B of part 50 of this 
chapter.

[51 FR 40661, Nov. 7, 1986]

    Editorial Note: For Federal Register citations affecting Sec. 
51.100, see the List of CFR Sections Affected, which appears in the 
Finding Aids section of the printed volume and at www.govinfo.gov.



Sec. 51.101  Stipulations.

    Nothing in this part will be construed in any manner:
    (a) To encourage a State to prepare, adopt, or submit a plan which 
does not provide for the protection and enhancement of air quality so as 
to promote the public health and welfare and productive capacity.
    (b) To encourage a State to adopt any particular control strategy 
without taking into consideration the cost-effectiveness of such control 
strategy in relation to that of alternative control strategies.
    (c) To preclude a State from employing techniques other than those 
specified in this part for purposes of estimating air quality or 
demonstrating the adequacy of a control strategy,

[[Page 186]]

provided that such other techniques are shown to be adequate and 
appropriate for such purposes.
    (d) To encourage a State to prepare, adopt, or submit a plan without 
taking into consideration the social and economic impact of the control 
strategy set forth in such plan, including, but not limited to, impact 
on availability of fuels, energy, transportation, and employment.
    (e) To preclude a State from preparing, adopting, or submitting a 
plan which provides for attainment and maintenance of a national 
standard through the application of a control strategy not specifically 
identified or described in this part.
    (f) To preclude a State or political subdivision thereof from 
adopting or enforcing any emission limitations or other measures or 
combinations thereof to attain and maintain air quality better than that 
required by a national standard.
    (g) To encourage a State to adopt a control strategy uniformly 
applicable throughout a region unless there is no satisfactory 
alternative way of providing for attainment and maintenance of a 
national standard throughout such region.

[61 FR 30163, June 14, 1996]



Sec. 51.102  Public hearings.

    (a) Except as otherwise provided in paragraph (c) of this section 
and within the 30 day notification period as required by paragraph (d) 
of this section, States must provide notice, provide the opportunity to 
submit written comments and allow the public the opportunity to request 
a public hearing. The State must hold a public hearing or provide the 
public the opportunity to request a public hearing. The notice 
announcing the 30 day notification period must include the date, place 
and time of the public hearing. If the State provides the public the 
opportunity to request a public hearing and a request is received the 
State must hold the scheduled hearing or schedule a public hearing (as 
required by paragraph (d) of this section). The State may cancel the 
public hearing through a method it identifies if no request for a public 
hearing is received during the 30 day notification period and the 
original notice announcing the 30 day notification period clearly 
states: If no request for a public hearing is received the hearing will 
be cancelled; identifies the method and time for announcing that the 
hearing has been cancelled; and provides a contact phone number for the 
public to call to find out if the hearing has been cancelled. These 
requirements apply for adoption and submission to EPA of:
    (1) Any plan or revision of it required by Sec. 51.104(a).
    (2) Any individual compliance schedule under (Sec. 51.260).
    (3) Any revision under Sec. 51.104(d).
    (b) Separate hearings may be held for plans to implement primary and 
secondary standards.
    (c) No hearing will be required for any change to an increment of 
progress in an approved individual compliance schedule unless such 
change is likely to cause the source to be unable to comply with the 
final compliance date in the schedule. The requirements of Sec. Sec. 
51.104 and 51.105 will be applicable to such schedules, however.
    (d) Any hearing required by paragraph (a) of this section will be 
held only after reasonable notice, which will be considered to include, 
at least 30 days prior to the date of such hearing(s):
    (1) Notice given to the public by prominent advertisement in the 
area affected announcing the date(s), time(s), and place(s) of such 
hearing(s);
    (2) Availability of each proposed plan or revision for public 
inspection in at least one location in each region to which it will 
apply, and the availability of each compliance schedule for public 
inspection in at least one location in the region in which the affected 
source is located;
    (3) Notification to the Administrator (through the appropriate 
Regional Office);
    (4) Notification to each local air pollution control agency which 
will be significantly impacted by such plan, schedule or revision;
    (5) In the case of an interstate region, notification to any other 
States included, in whole or in part, in the regions which are 
significantly impacted by such plan or schedule or revision.

[[Page 187]]

    (e) The State must prepare and retain, for inspection by the 
Administrator upon request, a record of each hearing. The record must 
contain, as a minimum, a list of witnesses together with the text of 
each presentation.
    (f) The State must submit with the plan, revision, or schedule, a 
certification that the requirements in paragraph (a) and (d) of this 
section were met. Such certification will include the date and place of 
any public hearing(s) held or that no public hearing was requested 
during the 30 day notification period.
    (g) Upon written application by a State agency (through the 
appropriate Regional Office), the Administrator may approve State 
procedures for public hearings. The following criteria apply:
    (1) Procedures approved under this section shall be deemed to 
satisfy the requirement of this part regarding public hearings.
    (2) Procedures different from this part may be approved if they--
    (i) Ensure public participation in matters for which hearings are 
required; and
    (ii) Provide adequate public notification of the opportunity to 
participate.
    (3) The Administrator may impose any conditions on approval he or 
she deems necessary.

[36 FR 22938, Nov. 25, 1971, as amended at 65 FR 8657, Feb. 22, 2000; 72 
FR 38792, July 16, 2007]



Sec. 51.103  Submission of plans, preliminary review of plans.

    (a) The State makes an official plan submission to EPA only when the 
submission conforms to the requirements of appendix V to this part and 
the State delivers the submission to EPA through one of the three 
following methods: An electronic submission through EPA's eSIP 
submission system; one paper submission to the appropriate Regional 
Office with an exact duplicate electronic version, preferably in a word 
searchable format; or three paper submissions. Any State submission 
under this part, whether through the eSIP submission system or in paper 
copy form, will serve as the official submission.
    (b) Upon request by a State, the Administrator will work with the 
State to provide preliminary review of a plan or portion thereof 
submitted in advance of the date such plan is due. Such requests must be 
made to the appropriate Regional Office, and must indicate changes (such 
as redline/strikethrough) to the existing approved plan where 
applicable, and be submitted using a format agreed upon by the State and 
Regional Office. Requests for preliminary review do not relieve a State 
of the responsibility of adopting and submitting plans in accordance 
with prescribed due dates.
    (c) In addition to conforming to the requirements of appendix V to 
this part for complete SIP submissions, the EPA requests that the state 
consult with the appropriate Regional Office regarding any additional 
guidance for submitting a plan to EPA.

[80 FR 7340, Feb. 10, 2015]



Sec. 51.104  Revisions.

    (a) States may revise the plan from time to time consistent with the 
requirements applicable to implementation plans under this part.
    (b) The States must submit any revision of any regulation or any 
compliance schedule under paragraph (c) of this section to the 
Administrator no later than 60 days after its adoption.
    (c) EPA will approve revisions only after applicable hearing 
requirements of Sec. 51.102 have been satisfied.
    (d) In order for a variance to be considered for approval as a 
revision to the State implementation plan, the State must submit it in 
accordance with the requirements of this section.

[51 FR 40661, Nov. 7, 1986, as amended at 61 FR 16060, Apr. 11, 1996]



Sec. 51.105  Approval of plans.

    Revisions of a plan, or any portion thereof, will not be considered 
part of an applicable plan until such revisions have been approved by 
the Administrator in accordance with this part.

[51 FR 40661, Nov. 7, 1986, as amended at 60 FR 33922, June 29, 1995]

[[Page 188]]



                       Subpart G_Control Strategy

    Source: 51 FR 40665, Nov. 7, 1986, unless otherwise noted.



Sec. 51.110  Attainment and maintenance of national standards.

    (a) Each plan providing for the attainment of a primary or secondary 
standard must specify the projected attainment date.
    (b)-(f) [Reserved]
    (g) During developing of the plan, EPA encourages States to identify 
alternative control strategies, as well as the costs and benefits of 
each such alternative for attainment or maintenance of the national 
standard.

[51 FR 40661 Nov. 7, 1986, as amended at 61 FR 16060, Apr. 11, 1996; 61 
FR 30163, June 14, 1996]



Sec. 51.111  Description of control measures.

    Each plan must set forth a control strategy which includes the 
following:
    (a) A description of enforcement methods including, but not limited 
to:
    (1) Procedures for monitoring compliance with each of the selected 
control measures,
    (2) Procedures for handling violations, and
    (3) A designation of agency responsibility for enforcement of 
implementation.
    (b) [Reserved]

[51 FR 40665, Nov. 7, 1986, as amended at 60 FR 33922, June 29, 1995]



Sec. 51.112  Demonstration of adequacy.

    (a) Each plan must demonstrate that the measures, rules, and 
regulations contained in it are adequate to provide for the timely 
attainment and maintenance of the national standard that it implements.
    (1) The adequacy of a control strategy shall be demonstrated by 
means of applicable air quality models, data bases, and other 
requirements specified in appendix W of this part (Guideline on Air 
Quality Models).
    (2) Where an air quality model specified in appendix W of this part 
(Guideline on Air Quality Models) is inappropriate, the model may be 
modified or another model substituted. Such a modification or 
substitution of a model may be made on a case-by-case basis or, where 
appropriate, on a generic basis for a specific State program. Written 
approval of the Administrator must be obtained for any modification or 
substitution. In addition, use of a modified or substituted model must 
be subject to notice and opportunity for public comment under procedures 
set forth in Sec. 51.102.
    (b) The demonstration must include the following:
    (1) A summary of the computations, assumptions, and judgments used 
to determine the degree of reduction of emissions (or reductions in the 
growth of emissions) that will result from the implementation of the 
control strategy.
    (2) A presentation of emission levels expected to result from 
implementation of each measure of the control strategy.
    (3) A presentation of the air quality levels expected to result from 
implementation of the overall control strategy presented either in 
tabular form or as an isopleth map showing expected maximum pollutant 
concentrations.
    (4) A description of the dispersion models used to project air 
quality and to evaluate control strategies.
    (5) For interstate regions, the analysis from each constituent State 
must, where practicable, be based upon the same regional emission 
inventory and air quality baseline.

[51 FR 40665, Nov. 7, 1986, as amended at 58 FR 38821, July 20, 1993; 60 
FR 40468, Aug. 9, 1995; 61 FR 41840, Aug. 12, 1996]



Sec. 51.113  [Reserved]



Sec. 51.114  Emissions data and projections.

    (a) Except for lead, each plan must contain a detailed inventory of 
emissions from point and area sources. Lead requirements are specified 
in Sec. 51.117. The inventory must be based upon measured emissions or, 
where measured emissions are not available, documented emission factors.
    (b) Each plan must contain a summary of emission levels projected to 
result from application of the new control strategy.

[[Page 189]]

    (c) Each plan must identify the sources of the data used in the 
projection of emissions.



Sec. 51.115  Air quality data and projections.

    (a) Each plan must contain a summary of data showing existing air 
quality.
    (b) Each plan must:
    (1) Contain a summary of air quality concentrations expected to 
result from application of the control strategy, and
    (2) Identify and describe the dispersion model, other air quality 
model, or receptor model used.
    (c) Actual measurements of air quality must be used where available 
if made by methods specified in appendix C to part 58 of this chapter. 
Estimated air quality using appropriate modeling techniques may be used 
to supplement measurements.
    (d) For purposes of developing a control strategy, background 
concentration shall be taken into consideration with respect to 
particulate matter. As used in this subpart, background concentration is 
that portion of the measured ambient levels that cannot be reduced by 
controlling emissions from man-made sources.
    (e) In developing an ozone control strategy for a particular area, 
background ozone concentrations and ozone transported into an area must 
be considered. States may assume that the ozone standard will be 
attained in upwind areas.



Sec. 51.116  Data availability.

    (a) The State must retain all detailed data and calculations used in 
the preparation of each plan or each plan revision, and make them 
available for public inspection and submit them to the Administrator at 
his request.
    (b) The detailed data and calculations used in the preparation of 
plan revisions are not considered a part of the plan.
    (c) Each plan must provide for public availability of emission data 
reported by source owners or operators or otherwise obtained by a State 
or local agency. Such emission data must be correlated with applicable 
emission limitations or other measures. As used in this paragraph, 
correlated means presented in such a manner as to show the relationship 
between measured or estimated amounts of emissions and the amounts of 
such emissions allowable under the applicable emission limitations or 
other measures.



Sec. 51.117  Additional provisions for lead.

    In addition to other requirements in Sec. Sec. 51.100 through 
51.116 the following requirements apply to lead. To the extent they 
conflict, there requirements are controlling over those of the 
proceeding sections.
    (a) Control strategy demonstration. Each plan must contain a 
demonstration showing that the plan will attain and maintain the 
standard in the following areas:
    (1) Areas in the vicinity of the following point sources of lead: 
Primary lead smelters, Secondary lead smelters, Primary copper smelters, 
Lead gasoline additive plants, Lead-acid storage battery manufacturing 
plants that produce 2,000 or more batteries per day. Any other 
stationary source that actually emits 25 or more tons per year of lead 
or lead compounds measured as elemental lead.
    (2) Any other area that has lead air concentrations in excess of the 
national ambient air quality standard concentration for lead, measured 
since January 1, 1974.
    (b) Time period for demonstration of adequacy. The demonstration of 
adequacy of the control strategy required under Sec. 51.112 may cover a 
longer period if allowed by the appropriate EPA Regional Administrator.
    (c) Special modeling provisions. (1) For urbanized areas with 
measured lead concentrations in excess of 4.0 [micro]g/m\3\, quarterly 
mean measured since January 1, 1974, the plan must employ the modified 
rollback model for the demonstration of attainment as a minimum, but may 
use an atmospheric dispersion model if desired, consistent with 
requirements contained in Sec. 51.112(a). If a proportional model is 
used, the air quality data should be the same year as the emissions 
inventory required under the paragraph e.
    (2) For each point source listed in Sec. 51.117(a), that plan must 
employ an atmospheric dispersion model for demonstration of attainment, 
consistent

[[Page 190]]

with requirements contained in Sec. 51.112(a).
    (3) For each area in the vicinity of an air quality monitor that has 
recorded lead concentrations in excess of the lead national standard 
concentration, the plan must employ the modified rollback model as a 
minimum, but may use an atmospheric dispersion model if desired for the 
demonstration of attainment, consistent with requirements contained in 
Sec. 51.112(a).
    (d) Air quality data and projections. (1) Each State must submit to 
the appropriate EPA Regional Office with the plan, but not part of the 
plan, all lead air quality data measured since January 1, 1974. This 
requirement does not apply if the data has already been submitted.
    (2) The data must be submitted in accordance with the procedures and 
data forms specified in Chapter 3.4.0 of the ``AEROS User's Manual'' 
concerning storage and retrieval of aerometric data (SAROAD) except 
where the Regional Administrator waives this requirement.
    (3) If additional lead air quality data are desired to determine 
lead air concentrations in areas suspected of exceeding the lead 
national ambient air quality standard, the plan may include data from 
any previously collected filters from particulate matter high volume 
samplers. In determining the lead content of the filters for control 
strategy demonstration purposes, a State may use, in addition to the 
reference method, X-ray fluorescence or any other method approved by the 
Regional Administrator.
    (e) Emissions data. (1) The point source inventory on which the 
summary of the baseline for lead emissions inventory is based must 
contain all sources that emit 0.5 or more tons of lead per year.
    (2) Each State must submit lead emissions data to the appropriate 
EPA Regional Office with the original plan. The submission must be made 
with the plan, but not as part of the plan, and must include emissions 
data and information related to point and area source emissions. The 
emission data and information should include the information identified 
in the Hazardous and Trace Emissions System (HATREMS) point source 
coding forms for all point sources and the area source coding forms for 
all sources that are not point sources, but need not necessarily be in 
the format of those forms.

[41 FR 18388, May 3, 1976, as amended at 58 FR 38822, July 20, 1993; 73 
FR 67057, Nov. 12, 2008]



Sec. 51.118  Stack height provisions.

    (a) The plan must provide that the degree of emission limitation 
required of any source for control of any air pollutant must not be 
affected by so much of any source's stack height that exceeds good 
engineering practice or by any other dispersion technique, except as 
provided in Sec. 51.118(b). The plan must provide that before a State 
submits to EPA a new or revised emission limitation that is based on a 
good engineering practice stack height that exceeds the height allowed 
by Sec. 51.100(ii) (1) or (2), the State must notify the public of the 
availabilty of the demonstration study and must provide opportunity for 
a public hearing on it. This section does not require the plan to 
restrict, in any manner, the actual stack height of any source.
    (b) The provisions of Sec. 51.118(a) shall not apply to (1) stack 
heights in existence, or dispersion techniques implemented on or before 
December 31, 1970, except where pollutants are being emitted from such 
stacks or using such dispersion techniques by sources, as defined in 
section 111(a)(3) of the Clean Air Act, which were constructed, or 
reconstructed, or for which major modifications, as defined in 
Sec. Sec. 51.165(a)(1)(v)(A), 51.166(b)(2)(i) and 52.21(b)(2)(i), were 
carried out after December 31, 1970; or (2) coal-fired steam electric 
generating units subject to the provisions of section 118 of the Clean 
Air Act, which commenced operation before July 1, 1957, and whose stacks 
were construced under a construction contract awarded before February 8, 
1974.



Sec. 51.119  Intermittent control systems.

    (a) The use of an intermittent control system (ICS) may be taken 
into account in establishing an emission limitation for a pollutant 
under a State implementation plan, provided:

[[Page 191]]

    (1) The ICS was implemented before December 31, 1970, according to 
the criteria specified in Sec. 51.119(b).
    (2) The extent to which the ICS is taken into account is limited to 
reflect emission levels and associated ambient pollutant concentrations 
that would result if the ICS was the same as it was before December 31, 
1970, and was operated as specified by the operating system of the ICS 
before December 31, 1970.
    (3) The plan allows the ICS to compensate only for emissions from a 
source for which the ICS was implemented before December 31, 1970, and, 
in the event the source has been modified, only to the extent the 
emissions correspond to the maximum capacity of the source before 
December 31, 1970. For purposes of this paragraph, a source for which 
the ICS was implemented is any particular structure or equipment the 
emissions from which were subject to the ICS operating procedures.
    (4) The plan requires the continued operation of any constant 
pollution control system which was in use before December 31, 1970, or 
the equivalent of that system.
    (5) The plan clearly defines the emission limits affected by the ICS 
and the manner in which the ICS is taken into account in establishing 
those limits.
    (6) The plan contains requirements for the operation and maintenance 
of the qualifying ICS which, together with the emission limitations and 
any other necessary requirements, will assure that the national ambient 
air quality standards and any applicable prevention of significant 
deterioration increments will be attained and maintained. These 
requirements shall include, but not necessarily be limited to, the 
following:
    (i) Requirements that a source owner or operator continuously 
operate and maintain the components of the ICS specified at Sec. 
51.119(b)(3) (ii)-(iv) in a manner which assures that the ICS is at 
least as effective as it was before December 31, 1970. The air quality 
monitors and meteorological instrumentation specified at Sec. 51.119(b) 
may be operated by a local authority or other entity provided the source 
has ready access to the data from the monitors and instrumentation.
    (ii) Requirements which specify the circumstances under which, the 
extent to which, and the procedures through which, emissions shall be 
curtailed through the activation of ICS.
    (iii) Requirements for recordkeeping which require the owner or 
operator of the source to keep, for periods of at least 3 years, records 
of measured ambient air quality data, meteorological information 
acquired, and production data relating to those processes affected by 
the ICS.
    (iv) Requirements for reporting which require the owner or operator 
of the source to notify the State and EPA within 30 days of a NAAQS 
violation pertaining to the pollutant affected by the ICS.
    (7) Nothing in this paragraph affects the applicability of any new 
source review requirements or new source performance standards contained 
in the Clean Air Act or 40 CFR subchapter C. Nothing in this paragraph 
precludes a State from taking an ICS into account in establishing 
emission limitations to any extent less than permitted by this 
paragraph.
    (b) An intermittent control system (ICS) may be considered 
implemented for a pollutant before December 31, 1970, if the following 
criteria are met:
    (1) The ICS must have been established and operational with respect 
to that pollutant prior to December 31, 1970, and reductions in 
emissions of that pollutant must have occurred when warranted by 
meteorological and ambient monitoring data.
    (2) The ICS must have been designed and operated to meet an air 
quality objective for that pollutant such as an air quality level or 
standard.
    (3) The ICS must, at a minimum, have included the following 
components prior to December 31, 1970:
    (i) Air quality monitors. An array of sampling stations whose 
location and type were consistent with the air quality objective and 
operation of the system.
    (ii) Meteorological instrumentation. A meteorological data 
acquisition network (may be limited to a single station) which provided 
meteorological

[[Page 192]]

prediction capabilities sufficient to determine the need for, and degree 
of, emission curtailments necessary to achieve the air quality design 
objective.
    (iii) Operating system. A system of established procedures for 
determining the need for curtailments and for accomplishing such 
curtailments. Documentation of this system, as required by paragraph 
(n)(4), may consist of a compendium of memoranda or comparable material 
which define the criteria and procedures for curtailments and which 
identify the type and number of personnel authorized to initiate 
curtailments.
    (iv) Meteorologist. A person, schooled in meteorology, capable of 
interpreting data obtained from the meteorological network and qualified 
to forecast meteorological incidents and their effect on ambient air 
quality. Sources may have obtained meteorological services through a 
consultant. Services of such a consultant could include sufficient 
training of source personnel for certain operational procedures, but not 
for design, of the ICS.
    (4) Documentation sufficient to support the claim that the ICS met 
the criteria listed in this paragraph must be provided. Such 
documentation may include affidavits or other documentation.



Sec. 51.120  Requirements for State Implementation Plan revisions 
relating to new motor vehicles.

    (a) The EPA Administrator finds that the State Implementation Plans 
(SIPs) for the States of Connecticut, Delaware, Maine, Maryland, 
Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode 
Island, and Vermont, the portion of Virginia included (as of November 
15, 1990) within the Consolidated Metropolitan Statistical Area that 
includes the District of Columbia, are substantially inadequate to 
comply with the requirements of section 110(a)(2)(D) of the Clean Air 
Act, 42 U.S.C. 7410(a)(2)(D), and to mitigate adequately the interstate 
pollutant transport described in section 184 of the Clean Air Act, 42 
U.S.C. 7511C, to the extent that they do not provide for emission 
reductions from new motor vehicles in the amount that would be achieved 
by the Ozone Transport Commission low emission vehicle (OTC LEV) program 
described in paragraph (c) of this section. This inadequacy will be 
deemed cured for each of the aforementioned States (including the 
District of Columbia) in the event that EPA determines through 
rulemaking that a national LEV-equivalent new motor vehicle emission 
control program is an acceptable alternative for OTC LEV and finds that 
such program is in effect. In the event no such finding is made, each of 
those States must adopt and submit to EPA by February 15, 1996 a SIP 
revision meeting the requirements of paragraph (b) of this section in 
order to cure the SIP inadequacy.
    (b) If a SIP revision is required under paragraph (a) of this 
section, it must contain the OTC LEV program described in paragraph (c) 
of this section unless the State adopts and submits to EPA, as a SIP 
revision, other emission-reduction measures sufficient to meet the 
requirements of paragraph (d) of this section. If a State adopts and 
submits to EPA, as a SIP revision, other emission-reduction measures 
pursuant to paragraph (d) of this section, then for purposes of 
determining whether such a SIP revision is complete within the meaning 
of section 110(k)(1) (and hence is eligible at least for consideration 
to be approved as satisfying paragraph (d) of this section), such a SIP 
revision must contain other adopted emission-reduction measures that, 
together with the identified potentially broadly practicable measures, 
achieve at least the minimum level of emission reductions that could 
potentially satisfy the requirements of paragraph (d) of this section. 
All such measures must be fully adopted and enforceable.
    (c) The OTC LEV program is a program adopted pursuant to section 177 
of the Clean Air Act.
    (1) The OTC LEV program shall contain the following elements:
    (i) It shall apply to all new 1999 and later model year passenger 
cars and light-duty trucks (0-5750 pounds loaded vehicle weight), as 
defined in Title 13, California Code of Regulations, section 1900(b)(11) 
and (b)(8), respectively, that

[[Page 193]]

are sold, imported, delivered, purchased, leased, rented, acquired, 
received, or registered in any area of the State that is in the 
Northeast Ozone Transport Region as of December 19, 1994.
    (ii) All vehicles to which the OTC LEV program is applicable shall 
be required to have a certificate from the California Air Resources 
Board (CARB) affirming compliance with California standards.
    (iii) All vehicles to which this LEV program is applicable shall be 
required to meet the mass emission standards for Non-Methane Organic 
Gases (NMOG), Carbon Monoxide (CO), Oxides of Nitrogen (NOX), 
Formaldehyde (HCHO), and particulate matter (PM) as specified in Title 
13, California Code of Regulations, section 1960.1(f)(2) (and 
formaldehyde standards under section 1960.1(e)(2), as applicable) or as 
specified by California for certification as a TLEV (Transitional Low-
Emission Vehicle), LEV (Low-Emission Vehicle), ULEV (Ultra-Low-Emission 
Vehicle), or ZEV (Zero-Emission Vehicle) under section 1960.1(g)(1) (and 
section 1960.1(e)(3), for formaldehyde standards, as applicable).
    (iv) All manufacturers of vehicles subject to the OTC LEV program 
shall be required to meet the fleet average NMOG exhaust emission values 
for production and delivery for sale of their passenger cars, light-duty 
trucks 0-3750 pounds loaded vehicle weight, and light-duty trucks 3751-
5750 pounds loaded vehicle weight specified in Title 13, California Code 
of Regulations, section 1960.1(g)(2) for each model year beginning in 
1999. A State may determine not to implement the NMOG fleet average in 
the first model year of the program if the State begins implementation 
of the program late in a calendar year. However, all States must 
implement the NMOG fleet average in any full model years of the LEV 
program.
    (v) All manufacturers shall be allowed to average, bank and trade 
credits in the same manner as allowed under the program specified in 
Title 13, California Code of Regulations, section 1960.1(g)(2) footnote 
7 for each model year beginning in 1999. States may account for credits 
banked by manufacturers in California or New York in years immediately 
preceding model year 1999, in a manner consistent with California 
banking and discounting procedures.
    (vi) The provisions for small volume manufacturers and intermediate 
volume manufacturers, as applied by Title 13, California Code of 
Regulations to California's LEV program, shall apply. Those 
manufacturers defined as small volume manufacturers and intermediate 
volume manufacturers in California under California's regulations shall 
be considered small volume manufacturers and intermediate volume 
manufacturers under this program.
    (vii) The provisions for hybrid electric vehicles (HEVs), as defined 
in Title 13 California Code of Regulations, section 1960.1, shall apply 
for purposes of calculating fleet average NMOG values.
    (viii) The provisions for fuel-flexible vehicles and dual-fuel 
vehicles specified in Title 13, California Code of Regulations, section 
1960.1(g)(1) footnote 4 shall apply.
    (ix) The provisions for reactivity adjustment factors, as defined by 
Title 13, California Code of Regulations, shall apply.
    (x) The aforementioned State OTC LEV standards shall be identical to 
the aforementioned California standards as such standards exist on 
December 19, 1994.
    (xi) All States' OTC LEV programs must contain any other provisions 
of California's LEV program specified in Title 13, California Code of 
Regulations necessary to comply with section 177 of the Clean Air Act.
    (2) States are not required to include the mandate for production of 
ZEVs specified in Title 13, California Code of Regulations, section 
1960.1(g)(2) footnote 9.
    (3) Except as specified elsewhere in this section, States may 
implement the OTC LEV program in any manner consistent with the Act that 
does not decrease the emissions reductions or jeopardize the 
effectiveness of the program.
    (d) The SIP revision that paragraph (b) of this section describes as 
an alternative to the OTC LEV program described in paragraph (c) of this 
section must contain a set of State-adopted

[[Page 194]]

measures that provides at least the following amount of emission 
reductions in time to bring serious ozone nonattainment areas into 
attainment by their 1999 attainment date:
    (1) Reductions at least equal to the difference between:
    (i) The nitrogen oxides (NOX) emission reductions from 
the 1990 statewide emissions inventory achievable through implementation 
of all of the Clean Air Act-mandated and potentially broadly practicable 
control measures throughout all portions of the State that are within 
the Northeast Ozone Transport Region created under section 184(a) of the 
Clean Air Act as of December 19, 1994; and
    (ii) A reduction in NOX emissions from the 1990 statewide 
inventory in such portions of the State of 50% or whatever greater 
reduction is necessary to prevent significant contribution to 
nonattainment in, or interference with maintenance by, any downwind 
State.
    (2) Reductions at least equal to the difference between:
    (i) The VOC emission reductions from the 1990 statewide emissions 
inventory achievable through implementation of all of the Clean Air Act-
mandated and potentially broadly practicable control measures in all 
portions of the State in, or near and upwind of, any of the serious or 
severe ozone nonattainment areas lying in the series of such areas 
running northeast from the Washington, DC, ozone nonattainment area to 
and including the Portsmouth, New Hampshire ozone nonattainment area; 
and
    (ii) A reduction in VOC emissions from the 1990 emissions inventory 
in all such areas of 50% or whatever greater reduction is necessary to 
prevent significant contribution to nonattainment in, or interference 
with maintenance by, any downwind State.

[60 FR 4736, Jan. 24, 1995]



Sec. 51.121  Findings and requirements for submission of State 
implementation plan revisions relating to emissions of nitrogen
oxides.

    (a)(1) The Administrator finds that the State implementation plan 
(SIP) for each jurisdiction listed in paragraph (c) of this section is 
substantially inadequate to comply with the requirements of section 
110(a)(2)(D)(i)(I) of the Clean Air Act (CAA), 42 U.S.C. 
7410(a)(2)(D)(i)(I), because the SIP does not include adequate 
provisions to prohibit sources and other activities from emitting 
nitrogen oxides (``NOX'') in amounts that will contribute 
significantly to nonattainment in one or more other States with respect 
to the 1-hour ozone national ambient air quality standards (NAAQS). Each 
of the jurisdictions listed in paragraph (c) of this section must submit 
to EPA a SIP revision that cures the inadequacy.
    (2) [Reserved]
    (3) As used in this section, these terms shall have the following 
meanings:
    Nitrogen oxides or NOX means all oxides of nitrogen except nitrous 
oxide (N2O), reported on an equivalent molecular weight basis 
as nitrogen dioxide (NO2).
    Ozone season means the period from May 1 to September 30 of a year.
    Phase I SIP submission means a SIP revision submitted by a State on 
or before October 30, 2000 in compliance with paragraph (b)(1)(ii) of 
this section to limit projected NOX emissions during the 
ozone season from sources in the relevant portion or all of the State, 
as applicable, to no more than the State's Phase I NOX ozone 
season budget under paragraph (e) of this section.
    Phase II SIP submission means a SIP revision submitted by a State in 
compliance with paragraph (b)(1)(ii) of this section to limit projected 
NOX emissions during the ozone season from sources in the 
relevant portion or all of the State, as applicable, to no more than the 
State's final NOX ozone season budget under paragraph (e) of 
this section.
    (b)(1) For each jurisdiction listed in paragraph (c) of this 
section, each SIP revision required under paragraph (a) of this section 
will contain adequate provisions, for purposes of complying with section 
110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), only if 
the SIP revision:
    (i) Contains control measures adequate to prohibit emissions of 
NOX that

[[Page 195]]

would otherwise be projected, in accordance with paragraph (g) of this 
section, to cause the jurisdiction's overall NOX emissions 
during the ozone season to be in excess of the applicable NOX 
ozone season budget for that jurisdiction described in paragraph (e) of 
this section;
    (ii) Requires full implementation of all such control measures by no 
later than May 31, 2004 for the sources covered by a Phase I SIP 
submission and May 1, 2007 for the sources covered by a Phase II SIP 
submission; and
    (iii) Meets the other requirements of this section. The SIP 
revision's compliance with the requirement of paragraph (b)(1)(i) of 
this section shall be considered compliance with the jurisdiction's 
NOX ozone season budget for purposes of this section.
    (2) [Reserved]
    (c) The following jurisdictions (hereinafter referred to as 
``States'') are subject to the requirement of this section:
    (1) Connecticut, Delaware, Illinois, Indiana, Kentucky, Maryland, 
Massachusetts, New Jersey, New York, North Carolina, Ohio, Pennsylvania, 
Rhode Island, South Carolina, Tennessee, Virginia, West Virginia, and 
the District of Columbia.
    (2) The portions of Alabama, Michigan, and Missouri within the fine 
grid of the OTAG modeling domain. The fine grid is the area encompassed 
by a box with the following geographic coordinates: Southwest Corner, 92 
degrees West longitude and 32 degrees North latitude; and Northeast 
Corner, 69.5 degrees West longitude and 44 degrees North latitude.
    (d)(1) [Reserved]
    (2) Each SIP submission under this section must comply with Sec. 
51.103 (regarding submission of plans).
    (e)(1) Except as provided in paragraph (e)(2)(ii) of this section, 
the NOX ozone season budget for a State listed in paragraph 
(c) of this section is defined as the total amount of NOX 
emissions from all sources in that State, as indicated in paragraph 
(e)(2)(i) of this section with respect to that State, which the State 
must demonstrate that it will not exceed in the 2007 ozone season 
pursuant to paragraph (g)(1) of this section.
    (2)(i) The State-by-State amounts of the Phase I and final 
NOX ozone season budgets, expressed in tons, are listed in 
Table 1 to this paragraph (e)(2)(i):

     Table 1 to Paragraph (e)(2)(i)--State NOX Ozone Season Budgets
------------------------------------------------------------------------
                                    Phase I NOX ozone   Final NOX ozone
                                      season budget      season budget
               State                   (2004-2006)         (2007 and
                                                          thereafter)
------------------------------------------------------------------------
Alabama...........................            124,795            119,827
Connecticut.......................             42,891             42,850
Delaware..........................             23,522             22,862
District of Columbia..............              6,658              6,657
Illinois..........................            278,146            271,091
Indiana...........................            234,625            230,381
Kentucky..........................            165,075            162,519
Maryland..........................             82,727             81,947
Massachusetts.....................             85,871             84,848
Michigan..........................            191,941            190,908
Missouri..........................  .................             61,406
New Jersey........................             95,882             96,876
New York..........................            241,981            240,322
North Carolina....................            171,332            165,306
Ohio..............................            252,282            249,541
Pennsylvania......................            268,158            257,928
Rhode Island......................              9,570              9,378
South Carolina....................            127,756            123,496
Tennessee.........................            201,163            198,286
Virginia..........................            186,689            180,521
West Virginia.....................             85,045             83,921
------------------------------------------------------------------------

    (ii) (A) For purposes of paragraph (e)(2)(i) of this section, in the 
case of each State listed in paragraphs (e)(2)(ii)(B) through (E) of 
this section, the NOX ozone season budget is defined as the 
total amount of NOX emissions from all sources in the 
specified counties in that State, as indicated in paragraph (e)(2)(i) of 
this section with respect to the State, which the State must demonstrate 
that it will not exceed in the 2007 ozone season pursuant to paragraph 
(g)(1) of this section.
    (B) In the case of Alabama, the counties are: Autauga, Bibb, Blount, 
Calhoun, Chambers, Cherokee, Chilton, Clay, Cleburne, Colbert, Coosa, 
Cullman, Dallas, DeKalb, Elmore, Etowah, Fayette, Franklin, Greene, 
Hale, Jackson, Jefferson, Lamar, Lauderdale, Lawrence, Lee, Limestone, 
Macon, Madison, Marion, Marshall, Morgan, Perry, Pickens, Randolph, 
Russell, St. Clair, Shelby, Sumter, Talladega, Tallapoosa, Tuscaloosa, 
Walker, and Winston.
    (C) [Reserved]
    (D) In the case of Michigan, the counties are: Allegan, Barry, Bay, 
Berrien, Branch, Calhoun, Cass, Clinton, Eaton, Genesee, Gratiot, 
Hillsdale, Ingham,

[[Page 196]]

Ionia, Isabella, Jackson, Kalamazoo, Kent, Lapeer, Lenawee, Livingston, 
Macomb, Mecosta, Midland, Monroe, Montcalm, Muskegon, Newaygo, Oakland, 
Oceana, Ottawa, Saginaw, St. Clair, St. Joseph, Sanilac, Shiawassee, 
Tuscola, Van Buren, Washtenaw, and Wayne.
    (E) In the case of Missouri, the counties are: Bollinger, Butler, 
Cape Girardeau, Carter, Clark, Crawford, Dent, Dunklin, Franklin, 
Gasconade, Iron, Jefferson, Lewis, Lincoln, Madison, Marion, 
Mississippi, Montgomery, New Madrid, Oregon, Pemiscot, Perry, Pike, 
Ralls, Reynolds, Ripley, St. Charles, St. Francois, St. Louis, St. Louis 
City, Ste. Genevieve, Scott, Shannon, Stoddard, Warren, Washington, and 
Wayne.
    (f) Each SIP revision must set forth control measures to meet the 
NOX ozone season budget in accordance with paragraph 
(b)(1)(i) of this section, which include the following:
    (1) A description of enforcement methods including, but not limited 
to:
    (i) Procedures for monitoring compliance with each of the selected 
control measures;
    (ii) Procedures for handling violations; and
    (iii) A designation of agency responsibility for enforcement of 
implementation.
    (2) Should a State elect to impose control measures on fossil fuel-
fired NOX sources serving electric generators with a 
nameplate capacity greater than 25 MWe or boilers, combustion turbines 
or combined cycle units with a maximum design heat input greater than 
250 mmBtu/hr as a means of meeting its NOX ozone season 
budget, then those measures must:
    (i)(A) Impose a NOX mass emissions cap on each source;
    (B) Impose a NOX emissions rate limit on each source and 
assume maximum operating capacity for every such source for purposes of 
estimating NOX mass emissions; or
    (C) Impose any other regulatory requirement which the State has 
demonstrated to EPA provides equivalent or greater assurance than 
options in paragraph (f)(2)(i)(A) or (B) of this section that the State 
will comply with its NOX ozone season budget in the 2007 
ozone season; and
    (ii) Impose enforceable mechanisms, in accordance with paragraphs 
(b)(1)(i) and (ii) of this section, to assure that collectively all such 
sources, including new or modified units, will not exceed in the 2007 
ozone season the total NOX emissions projected for such 
sources by the State pursuant to paragraph (g) of this section.
    (3) For purposes of paragraph (f)(2) of this section, the term 
``fossil fuel-fired'' means, with regard to a NOX source:
    (i) The combustion of fossil fuel, alone or in combination with any 
other fuel, where fossil fuel actually combusted comprises more than 50 
percent of the annual heat input on a Btu basis during any year starting 
in 1995 or, if a NOX source had no heat input starting in 
1995, during the last year of operation of the NOX source 
prior to 1995; or
    (ii) The combustion of fossil fuel, alone or in combination with any 
other fuel, where fossil fuel is projected to comprise more than 50 
percent of the annual heat input on a Btu basis during any year; 
provided that the NOX source shall be ``fossil fuel-fired'' 
as of the date, during such year, on which the NOX source 
begins combusting fossil fuel.
    (g)(1) Each SIP revision must demonstrate that the control measures 
contained in it are adequate to provide for the timely compliance with 
the State's NOX ozone season budget during the 2007 ozone 
season.
    (2) The demonstration must include the following:
    (i) Each revision must contain a detailed baseline inventory of 
NOX mass emissions during the ozone season from the following 
sources in the year 2007, absent the control measures specified in the 
SIP submission: electric generating units (EGU), non-electric generating 
units (non-EGU), area, nonroad and highway sources. The State must use 
the same baseline emissions inventory that EPA used in calculating the 
State's NOX ozone season budget, except that EPA may direct 
the State to use different baseline inventory information if the State 
fails to certify that it has implemented all of the control

[[Page 197]]

measures assumed in developing the baseline inventory.
    (ii) [Reserved]
    (iii) Each revision must contain a summary of NOX mass 
emissions during the ozone season in 2007 projected to result from 
implementation of each of the control measures specified in the SIP 
submission and from all NOX sources together following 
implementation of all such control measures, compared to the baseline 
2007 NOX emissions inventory for the State described in 
paragraph (g)(2)(i) of this section. The State must provide EPA with a 
summary of the computations, assumptions, and judgments used to 
determine the degree of reduction in projected 2007 NOX 
emissions that will be achieved from the implementation of the new 
control measures compared to the baseline emissions inventory.
    (iv) Each revision must identify the sources of the data used in the 
projection of emissions.
    (h) Each revision must comply with Sec. 51.116 (regarding data 
availability).
    (i) Each revision must provide for monitoring the status of 
compliance with any control measures adopted to meet the NOX 
ozone season budget. Specifically, the revision must meet the following 
requirements:
    (1) The revision must provide for legally enforceable procedures for 
requiring owners or operators of stationary sources to maintain records 
of and periodically report to the State:
    (i) Information on the amount of NOX emissions from the 
stationary sources; and
    (ii) Other information as may be necessary to enable the State to 
determine whether the sources are in compliance with applicable portions 
of the control measures;
    (2) The revision must comply with Sec. 51.212 (regarding testing, 
inspection, enforcement, and complaints);
    (3) If the revision contains any transportation control measures, 
then the revision must comply with Sec. 51.213 (regarding 
transportation control measures);
    (4) If the revision contains measures to control fossil fuel-fired 
NOX sources serving electric generators with a nameplate 
capacity greater than 25 MWe or boilers, combustion turbines or combined 
cycle units with a maximum design heat input greater than 250 mmBtu/hr, 
then the revision may require some or all such sources to comply with 
the full set of monitoring, recordkeeping, and reporting provisions of 
40 CFR part 75, subpart H. A State requiring such compliance authorizes 
the Administrator to assist the State in implementing the revision by 
carrying out the functions of the Administrator under such part.
    (5) For purposes of paragraph (i)(4) of this section, the term 
``fossil fuel-fired'' has the meaning set forth in paragraph (f)(3) of 
this section.
    (j) Each revision must show that the State has legal authority to 
carry out the revision, including authority to:
    (1) Adopt emissions standards and limitations and any other measures 
necessary for attainment and maintenance of the State's NOX 
ozone season budget specified in paragraph (e) of this section;
    (2) Enforce applicable laws, regulations, and standards, and seek 
injunctive relief;
    (3) Obtain information necessary to determine whether air pollution 
sources are in compliance with applicable laws, regulations, and 
standards, including authority to require recordkeeping and to make 
inspections and conduct tests of air pollution sources;
    (4) Require owners or operators of stationary sources to install, 
maintain, and use emissions monitoring devices and to make periodic 
reports to the State on the nature and amounts of emissions from such 
stationary sources; also authority for the State to make such data 
available to the public as reported and as correlated with any 
applicable emissions standards or limitations.
    (k)(1) The provisions of law or regulation which the State 
determines provide the authorities required under this section must be 
specifically identified, and copies of such laws or regulations must be 
submitted with the SIP revision.
    (2) Legal authority adequate to fulfill the requirements of 
paragraphs (j)(3) and (4) of this section may be delegated to the State 
under section 114 of the CAA, 42 U.S.C. 7414.

[[Page 198]]

    (l)(1) A revision may assign legal authority to local agencies in 
accordance with Sec. 51.232.
    (2) Each revision must comply with Sec. 51.240 (regarding general 
plan requirements).
    (m) Each revision must comply with Sec. 51.280 (regarding 
resources).
    (n) For purposes of the SIP revisions required by this section, EPA 
may make a finding as applicable under section 179(a)(1)-(4) of the CAA, 
42 U.S.C. 7509(a)(1)-(4), starting the sanctions process set forth in 
section 179(a) of the CAA. Any such finding will be deemed a finding 
under 40 CFR 52.31(c) and sanctions will be imposed in accordance with 
the order of sanctions and the terms for such sanctions established in 
40 CFR 52.31.
    (o) Each revision must provide for State compliance with the 
reporting requirements set forth in Sec. 51.122.
    (p)-(q) [Reserved]
    (r)(1) Notwithstanding any provisions of subparts A through I of 40 
CFR part 96 and any State's SIP to the contrary, with regard to any 
ozone season that occurs after September 30, 2008, the Administrator 
will not carry out any of the functions set forth for the Administrator 
in subparts A through I of 40 CFR part 96 or in any emissions trading 
program provisions in a State's SIP approved under this section.
    (2) Except as provided in 40 CFR 52.38(b)(13)(ii), a State whose SIP 
is approved as meeting the requirements of this section and that 
includes or included an emissions trading program approved under this 
section must revise the SIP to adopt control measures that satisfy the 
same portion of the State's NOX emissions reduction 
requirements under this section as the State projected such emissions 
trading program would satisfy.

[63 FR 57491, Oct. 27, 1998, as amended at 63 FR 71225, Dec. 24, 1998; 
64 FR 26305, May 14, 1999; 65 FR 11230, Mar. 2, 2000; 65 FR 56251, Sept. 
18, 2000; 69 FR 21642, Apr. 21, 2004; 70 FR 25317, May 12, 2005; 70 FR 
51597, Aug. 31, 2005; 73 FR 21538, Apr. 22, 2008; 76 FR 48353, Aug. 8, 
2011; 79 FR 71671, Dec. 3, 2014; 84 FR 8442, Mar. 8, 2019; 86 FR 23164, 
Apr. 30, 2021]



Sec. 51.122  Emissions reporting requirements for SIP revisions
relating to budgets for NOX emissions.

    (a) As used in this section, words and terms shall have the meanings 
set forth in Sec. 51.50. In addition, the following terms shall apply 
to this section:
    (1) Ozone season emissions means emissions during the period from 
May 1 through September 30 of a year.
    (2) Summer day emissions means an average day's emissions for a 
typical summer work weekday. The state will select the particular 
month(s) in summer and the day(s) in the work week to be represented.
    (b) For its transport SIP revision under Sec. 51.121, each state 
must submit to EPA NOX emissions data as described in this 
section.
    (c) Each revision must provide for periodic reporting by the state 
of NOX emissions data to demonstrate whether the state's 
emissions are consistent with the projections contained in its approved 
SIP submission.
    (1) For the every-year reporting cycle, each revision must provide 
for reporting of NOX emissions data every year as follows:
    (i) The state must report to EPA emissions data from all 
NOX sources within the state for which the state specified 
control measures in its SIP submission under Sec. 51.121(g), including 
all sources for which the state has adopted measures that differ from 
the measures incorporated into the baseline inventory for the year 2007 
that the state developed in accordance with Sec. 51.121(g).The state 
must also report to EPA ozone season emissions of NOX and 
summer day emissions of NOX from any point, nonpoint, onroad 
mobile, or nonroad mobile source for which the state specified control 
measures in its SIP submission under Sec. 51.121(g).
    (ii) If sources report NOX emissions data to EPA for a 
given year pursuant to the monitoring and reporting requirements of 40 
CFR part 75, then the state need not provide an every-year cycle report 
to EPA for such sources.
    (2) For the 3-year cycle reporting, each plan must provide for 
triennial (i.e., every third year) reporting of NOX emissions 
data from all sources within the state. The state must also report to

[[Page 199]]

EPA ozone season emissions of NOX and summer day emissions of 
NOX from all point sources, nonpoint sources, onroad mobile 
sources, and nonroad mobile sources.
    (3) The data availability requirements in Sec. 51.116 must be 
followed for all data submitted to meet the requirements of paragraphs 
(c)(1) and (2) of this section.
    (d) [Reserved]
    (e) Each state must submit for EPA approval an example of the 
calculation procedure used to calculate ozone season emissions along 
with sufficient information to verify the calculated value of ozone 
season emissions.
    (f) Data collection is to begin during the ozone season 1 year prior 
to the state's NOX SIP Call compliance date.
    (g) The state shall report emissions as point sources according to 
the point source emissions thresholds of the Air Emissions Reporting 
Rule (AERR), 40 CFR part 51, subpart A. The detail of the emissions 
inventory shall be consistent with the data elements required by 40 CFR 
part 51, subpart A. When submitting a formal NOX Budget 
Emissions Report and associated data, states shall notify the 
appropriate EPA Regional Office.

[73 FR 76558, Dec. 17, 2008, as amended at 80 FR 8796, Feb. 19, 2015; 84 
FR 8443, Mar. 8, 2019]



Sec. 51.123  Findings and requirements for submission of State
implementation plan revisions relating to emissions of oxides
of nitrogen pursuant to the Clean Air Interstate Rule.
          

    (a)(1) Under section 110(a)(1) of the CAA, 42 U.S.C. 7410(a)(1), the 
Administrator determines that each State identified in paragraph (c)(1) 
and (2) of this section must submit a SIP revision to comply with the 
requirements of section 110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 
7410(a)(2)(D)(i)(I), through the adoption of adequate provisions 
prohibiting sources and other activities from emitting NOX in 
amounts that will contribute significantly to nonattainment in, or 
interfere with maintenance by, one or more other States with respect to 
the fine particles (PM2.5) NAAQS.
    (2)(a) Under section 110(a)(1) of the CAA, 42 U.S.C. 7410(a)(1), the 
Administrator determines that each State identified in paragraph (c)(1) 
and (3) of this section must submit a SIP revision to comply with the 
requirements of section 110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 
7410(a)(2)(D)(i)(I), through the adoption of adequate provisions 
prohibiting sources and other activities from emitting NOX in 
amounts that will contribute significantly to nonattainment in, or 
interfere with maintenance by, one or more other States with respect to 
the 8-hour ozone NAAQS.
    (3) Notwithstanding the other provisions of this section, such 
provisions are not applicable as they relate to the State of Minnesota 
as of December 3, 2009.
    (b) For each State identified in paragraph (c) of this section, the 
SIP revision required under paragraph (a) of this section will contain 
adequate provisions, for purposes of complying with section 
110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), only if 
the SIP revision contains control measures that assure compliance with 
the applicable requirements of this section.
    (c) In addition to being subject to the requirements in paragraphs 
(b) and (d) of this section:
    (1) Alabama, Delaware, Florida, Illinois, Indiana, Iowa, Kentucky, 
Louisiana, Maryland, Michigan, Mississippi, Missouri, New Jersey, New 
York, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, 
Virginia, West Virginia, Wisconsin, and the District of Columbia shall 
be subject to the requirements contained in paragraphs (e) through (cc) 
of this section;
    (2) Georgia, Minnesota, and Texas shall be subject to the 
requirements in paragraphs (e) through (o) and (cc) of this section; and
    (3) Arkansas, Connecticut, and Massachusetts shall be subject to the 
requirements contained in paragraphs (q) through (cc) of this section.
    (d)(1) The State's SIP revision under paragraph (a) of this section 
must be submitted to EPA by no later than September 11, 2006.
    (2) The requirements of appendix V to this part shall apply to the 
SIP revision under paragraph (a) of this section.
    (3) The State shall deliver 5 copies of the SIP revision under 
paragraph (a) of

[[Page 200]]

this section to the appropriate Regional Office, with a letter giving 
notice of such action.
    (e) The State's SIP revision shall contain control measures and 
demonstrate that they will result in compliance with the State's Annual 
EGU NOX Budget, if applicable, and achieve the State's Annual 
Non-EGU NOX Reduction Requirement, if applicable, for the 
appropriate periods. The amounts of the State's Annual EGU 
NOX Budget and Annual Non-EGU NOX Reduction 
Requirement shall be determined as follows:
    (1)(i) The Annual EGU NOX Budget for the State is defined 
as the total amount of NOX emissions from all EGUs in that 
State for a year, if the State meets the requirements of paragraph 
(a)(1) of this section by imposing control measures, at least in part, 
on EGUs. If the State imposes control measures under this section on 
only EGUs, the Annual EGU NOX Budget for the State shall not 
exceed the amount, during the indicated periods, specified in paragraph 
(e)(2) of this section.
    (ii) The Annual Non-EGU NOX Reduction Requirement, if 
applicable, is defined as the total amount of NOX emission 
reductions that the State demonstrates, in accordance with paragraph (g) 
of this section, it will achieve from non-EGUs during the appropriate 
period. If the State meets the requirements of paragraph (a)(1) of this 
section by imposing control measures on only non-EGUs, then the State's 
Annual Non-EGU NOX Reduction Requirement shall equal or 
exceed, during the appropriate periods, the amount determined in 
accordance with paragraph (e)(3) of this section.
    (iii) If a State meets the requirements of paragraph (a)(1) of this 
section by imposing control measures on both EGUs and non-EGUs, then:
    (A) The Annual Non-EGU NOX Reduction Requirement shall 
equal or exceed the difference between the amount specified in paragraph 
(e)(2) of this section for the appropriate period and the amount of the 
State's Annual EGU NOX Budget specified in the SIP revision 
for the appropriate period; and
    (B) The Annual EGU NOX Budget shall not exceed, during 
the indicated periods, the amount specified in paragraph (e)(2) of this 
section plus the amount of the Annual Non-EGU NOX Reduction 
Requirement under paragraph (e)(1)(iii)(A) of this section for the 
appropriate period.
    (2) For a State that complies with the requirements of paragraph 
(a)(1) of this section by imposing control measures on only EGUs, the 
amount of the Annual EGU NOX Budget, in tons of 
NOX per year, shall be as follows, for the indicated State 
for the indicated period:

------------------------------------------------------------------------
                                                          Annual EGU NOX
                                          Annual EGU NOX    budget for
                  State                     budget for       2015 and
                                             2009-2014      thereafter
                                              (tons)          (tons)
------------------------------------------------------------------------
Alabama.................................          69,020          57,517
Delaware................................           4,166           3,472
District of Columbia....................             144             120
Florida.................................          99,445          82,871
Georgia.................................          66,321          55,268
Illinois................................          76,230          63,525
Indiana.................................         108,935          90,779
Iowa....................................          32,692          27,243
Kentucky................................          83,205          69,337
Louisiana...............................          35,512          29,593
Maryland................................          27,724          23,104
Michigan................................          65,304          54,420
Minnesota...............................          31,443          26,203
Mississippi.............................          17,807          14,839
Missouri................................          59,871          49,892
New Jersey..............................          12,670          10,558
New York................................          45,617          38,014
North Carolina..........................          62,183          51,819
Ohio....................................         108,667          90,556
Pennsylvania............................          99,049          82,541
South Carolina..........................          32,662          27,219
Tennessee...............................          50,973          42,478
Texas...................................         181,014         150,845
Virginia................................          36,074          30,062
West Virginia...........................          74,220          61,850
Wisconsin...............................          40,759          33,966
------------------------------------------------------------------------

    (3) For a State that complies with the requirements of paragraph 
(a)(1) of this section by imposing control measures on only non-EGUs, 
the amount of the Annual Non-EGU NOX Reduction Requirement, 
in tons of NOX per year, shall be determined, for the State 
for 2009 and thereafter, by subtracting the amount of the State's Annual 
EGU NOX Budget for the appropriate year, specified in 
paragraph (e)(2) of this section from the amount of the State's 
NOX baseline EGU emissions inventory projected for the 
appropriate year, specified in Table 5 of ``Regional and State 
SO2 and NOX Budgets'', March 2005 (available at 
http://www.epa.gov/cleanairinterstaterule).
    (4)(i) Notwithstanding the State's obligation to comply with 
paragraph

[[Page 201]]

(e)(2) or (3) of this section, the State's SIP revision may allow 
sources required by the revision to implement control measures to 
demonstrate compliance using credit issued from the State's compliance 
supplement pool, as set forth in paragraph (e)(4)(ii) of this section.
    (ii) The State-by-State amounts of the compliance supplement pool 
are as follows:

------------------------------------------------------------------------
                                                            Compliance
                          State                             supplement
                                                               pool
------------------------------------------------------------------------
Alabama.................................................          10,166
Delaware................................................             843
District of Columbia....................................               0
Florida.................................................           8,335
Georgia.................................................          12,397
Illinois................................................          11,299
Indiana.................................................          20,155
Iowa....................................................           6,978
Kentucky................................................          14,935
Louisiana...............................................           2,251
Maryland................................................           4,670
Michigan................................................           8,347
Minnesota...............................................           6,528
Mississippi.............................................           3,066
Missouri................................................           9,044
New Jersey..............................................             660
New York................................................               0
North Carolina..........................................               0
Ohio....................................................          25,037
Pennsylvania............................................          16,009
South Carolina..........................................           2,600
Tennessee...............................................           8,944
Texas...................................................             772
Virginia................................................           5,134
West Virginia...........................................          16,929
Wisconsin...............................................           4,898
------------------------------------------------------------------------

    (iii) The SIP revision may provide for the distribution of credits 
from the compliance supplement pool to sources that are required to 
implement control measures using one or both of the following two 
mechanisms:
    (A) The State may issue credit from compliance supplement pool to 
sources that are required by the SIP revision to implement 
NOX emission control measures and that implement 
NOX emission reductions in 2007 and 2008 that are not 
necessary to comply with any State or federal emissions limitation 
applicable at any time during such years. Such a source may be issued 
one credit from the compliance supplement pool for each ton of such 
emission reductions in 2007 and 2008.
    (1) The State shall complete the issuance process by January 1, 
2010.
    (2) The emissions reductions for which credits are issued must have 
been demonstrated by the owners and operators of the source to have 
occurred during 2007 and 2008 and not to be necessary to comply with any 
applicable State or federal emissions limitation.
    (3) The emissions reductions for which credits are issued must have 
been quantified by the owners and operators of the source:
    (i) For EGUs and for fossil-fuel-fired non-EGUs that are boilers or 
combustion turbines with a maximum design heat input greater than 250 
mmBut/hr, using emissions data determined in accordance with subpart H 
of part 75 of this chapter; and
    (ii) For non-EGUs not described in paragraph (e)(4)(iii)(A)(3)(i) of 
this section, using emissions data determined in accordance with subpart 
H of part 75 of this chapter or, if the State demonstrates that 
compliance with subpart H of part 75 of this chapter is not practicable, 
determined, to the extent practicable, with the same degree of assurance 
with which emissions data are determined for sources subject to subpart 
H of part 75.
    (4) If the SIP revision contains approved provisions for an 
emissions trading program, the owners and operators of sources that 
receive credit according to the requirements of this paragraph may 
transfer the credit to other sources or persons according to the 
provisions in the emissions trading program.
    (B) The State may issue credit from the compliance supplement pool 
to sources that are required by the SIP revision to implement 
NOX emission control measures and whose owners and operators 
demonstrate a need for an extension, beyond 2009, of the deadline for 
the source for implementing such emission controls.
    (1) The State shall complete the issuance process by January 1, 
2010.
    (2) The State shall issue credit to a source only if the owners and 
operators of the source demonstrate that:
    (i) For a source used to generate electricity, implementation of the 
SIP revision's applicable control measures by 2009 would create undue 
risk for the reliability of the electricity supply. This demonstration 
must include a showing that it would not be feasible for the owners and 
operators of the source to

[[Page 202]]

obtain a sufficient amount of electricity, to prevent such undue risk, 
from other electricity generation facilities during the installation of 
control technology at the source necessary to comply with the SIP 
revision.
    (ii) For a source not used to generate electricity, compliance with 
the SIP revision's applicable control measures by 2009 would create 
undue risk for the source or its associated industry to a degree that is 
comparable to the risk described in paragraph (e)(4)(iii)(B)(2)(i) of 
this section.
    (iii) This demonstration must include a showing that it would not be 
possible for the source to comply with applicable control measures by 
obtaining sufficient credits under paragraph (e)(4)(iii)(A) of this 
section, or by acquiring sufficient credits from other sources or 
persons, to prevent undue risk.
    (f) Each SIP revision must set forth control measures to meet the 
amounts specified in paragraph (e) of this section, as applicable, 
including the following:
    (1) A description of enforcement methods including, but not limited 
to:
    (i) Procedures for monitoring compliance with each of the selected 
control measures;
    (ii) Procedures for handling violations; and
    (iii) A designation of agency responsibility for enforcement of 
implementation.
    (2)(i) If a State elects to impose control measures on EGUs, then 
those measures must impose an annual NOX mass emissions cap 
on all such sources in the State.
    (ii) If a State elects to impose control measures on fossil fuel-
fired non-EGUs that are boilers or combustion turbines with a maximum 
design heat input greater than 250 mmBtu/hr, then those measures must 
impose an annual NOX mass emissions cap on all such sources 
in the State.
    (iii) If a State elects to impose control measures on non-EGUs other 
than those described in paragraph (f)(2)(ii) of this section, then those 
measures must impose an annual NOX mass emissions cap on all 
such sources in the State or the State must demonstrate why such 
emissions cap is not practicable and adopt alternative requirements that 
ensure that the State will comply with its requirements under paragraph 
(e) of this section, as applicable, in 2009 and subsequent years.
    (g)(1) Each SIP revision that contains control measures covering 
non-EGUs as part or all of a State's obligation in meeting its 
requirement under paragraph (a)(1) of this section must demonstrate that 
such control measures are adequate to provide for the timely compliance 
with the State's Annual Non-EGU NOX Reduction Requirement 
under paragraph (e) of this section and are not adopted or implemented 
by the State, as of May 12, 2005, and are not adopted or implemented by 
the Federal government, as of the date of submission of the SIP revision 
by the State to EPA.
    (2) The demonstration under paragraph (g)(1) of this section must 
include the following, with respect to each source category of non-EGUs 
for which the SIP revision requires control measures:
    (i) A detailed historical baseline inventory of NOX mass 
emissions from the source category in a representative year consisting, 
at the State's election, of 2002, 2003, 2004, or 2005, or an average of 
2 or more of those years, absent the control measures specified in the 
SIP revision.
    (A) This inventory must represent estimates of actual emissions 
based on monitoring data in accordance with subpart H of part 75 of this 
chapter, if the source category is subject to monitoring requirements in 
accordance with subpart H of part 75 of this chapter.
    (B) In the absence of monitoring data in accordance with subpart H 
of part 75 of this chapter, actual emissions must be quantified, to the 
maximum extent practicable, with the same degree of assurance with which 
emissions are quantified for sources subject to subpart H of part 75 of 
this chapter and using source-specific or source-category-specific 
assumptions that ensure a source's or source category's actual emissions 
are not overestimated. If a State uses factors to estimate emissions, 
production or utilization, or effectiveness of controls or rules for a 
source category, such factors must be

[[Page 203]]

chosen to ensure that emissions are not overestimated.
    (C) For measures to reduce emissions from motor vehicles, emission 
estimates must be based on an emissions model that has been approved by 
EPA for use in SIP development and must be consistent with the planning 
assumptions regarding vehicle miles traveled and other factors current 
at the time of the SIP development.
    (D) For measures to reduce emissions from nonroad engines or 
vehicles, emission estimates methodologies must be approved by EPA.
    (ii) A detailed baseline inventory of NOX mass emissions 
from the source category in the years 2009 and 2015, absent the control 
measures specified in the SIP revision and reflecting changes in these 
emissions from the historical baseline year to the years 2009 and 2015, 
based on projected changes in the production input or output, 
population, vehicle miles traveled, economic activity, or other factors 
as applicable to this source category.
    (A) These inventories must account for implementation of any control 
measures that are otherwise required by final rules already promulgated, 
as of May 12, 2005, or adopted or implemented by any federal agency, as 
of the date of submission of the SIP revision by the State to EPA, and 
must exclude any control measures specified in the SIP revision to meet 
the NOX emissions reduction requirements of this section.
    (B) Economic and population forecasts must be as specific as 
possible to the applicable industry, State, and county of the source or 
source category and must be consistent with both national projections 
and relevant official planning assumptions, including estimates of 
population and vehicle miles traveled developed through consultation 
between State and local transportation and air quality agencies. 
However, if these official planning assumptions are inconsistent with 
official U.S. Census projections of population or with energy 
consumption projections contained in the U.S. Department of Energy's 
most recent Annual Energy Outlook, then the SIP revision must make 
adjustments to correct the inconsistency or must demonstrate how the 
official planning assumptions are more accurate.
    (C) These inventories must account for any changes in production 
method, materials, fuels, or efficiency that are expected to occur 
between the historical baseline year and 2009 or 2015, as appropriate.
    (iii) A projection of NOX mass emissions in 2009 and 2015 
from the source category assuming the same projected changes as under 
paragraph (g)(2)(ii) of this section and resulting from implementation 
of each of the control measures specified in the SIP revision.
    (A) These inventories must address the possibility that the State's 
new control measures may cause production or utilization, and emissions, 
to shift to unregulated or less stringently regulated sources in the 
source category in the same or another State, and these inventories must 
include any such amounts of emissions that may shift to such other 
sources.
    (B) The State must provide EPA with a summary of the computations, 
assumptions, and judgments used to determine the degree of reduction in 
projected 2009 and 2015 NOX emissions that will be achieved 
from the implementation of the new control measures compared to the 
relevant baseline emissions inventory.
    (iv) The result of subtracting the amounts in paragraph (g)(2)(iii) 
of this section for 2009 and 2015, respectively, from the lower of the 
amounts in paragraph (g)(2)(i) or (g)(2)(ii) of this section for 2009 
and 2015, respectively, may be credited towards the State's Annual Non-
EGU NOX Reduction Requirement in paragraph (e)(3) of this 
section for the appropriate period.
    (v) Each SIP revision must identify the sources of the data used in 
each estimate and each projection of emissions.
    (h) Each SIP revision must comply with Sec. 51.116 (regarding data 
availability).
    (i) Each SIP revision must provide for monitoring the status of 
compliance with any control measures adopted to meet the State's 
requirements under paragraph (e) of this section as follows:

[[Page 204]]

    (1) The SIP revision must provide for legally enforceable procedures 
for requiring owners or operators of stationary sources to maintain 
records of, and periodically report to the State:
    (i) Information on the amount of NOX emissions from the 
stationary sources; and
    (ii) Other information as may be necessary to enable the State to 
determine whether the sources are in compliance with applicable portions 
of the control measures;
    (2) The SIP revision must comply with Sec. 51.212 (regarding 
testing, inspection, enforcement, and complaints);
    (3) If the SIP revision contains any transportation control 
measures, then the SIP revision must comply with Sec. 51.213 (regarding 
transportation control measures);
    (4)(i) If the SIP revision contains measures to control EGUs, then 
the SIP revision must require such sources to comply with the 
monitoring, recordkeeping, and reporting provisions of subpart H of part 
75 of this chapter.
    (ii) If the SIP revision contains measures to control fossil fuel-
fired non-EGUs that are boilers or combustion turbines with a maximum 
design heat input greater than 250 mmBtu/hr, then the SIP revision must 
require such sources to comply with the monitoring, recordkeeping, and 
reporting provisions of subpart H of part 75 of this chapter.
    (iii) If the SIP revision contains measures to control any other 
non-EGUs that are not described in paragraph (i)(4)(ii) of this section, 
then the SIP revision must require such sources to comply with the 
monitoring, recordkeeping, and reporting provisions of subpart H of part 
75 of this chapter, or the State must demonstrate why such requirements 
are not practicable and adopt alternative requirements that ensure that 
the required emissions reductions will be quantified, to the maximum 
extent practicable, with the same degree of assurance with which 
emissions are quantified for sources subject to subpart H of part 75 of 
this chapter.
    (j) Each SIP revision must show that the State has legal authority 
to carry out the SIP revision, including authority to:
    (1) Adopt emissions standards and limitations and any other measures 
necessary for attainment and maintenance of the State's relevant Annual 
EGU NOX Budget or the Annual Non-EGU NOX Reduction 
Requirement, as applicable, under paragraph (e) of this section;
    (2) Enforce applicable laws, regulations, and standards and seek 
injunctive relief;
    (3) Obtain information necessary to determine whether air pollution 
sources are in compliance with applicable laws, regulations, and 
standards, including authority to require recordkeeping and to make 
inspections and conduct tests of air pollution sources; and
    (4)(i) Require owners or operators of stationary sources to install, 
maintain, and use emissions monitoring devices and to make periodic 
reports to the State on the nature and amounts of emissions from such 
stationary sources; and
    (ii) Make the data described in paragraph (j)(4)(i) of this section 
available to the public within a reasonable time after being reported 
and as correlated with any applicable emissions standards or 
limitations.
    (k)(1) The provisions of law or regulation that the State determines 
provide the authorities required under this section must be specifically 
identified, and copies of such laws or regulations must be submitted 
with the SIP revision.
    (2) Legal authority adequate to fulfill the requirements of 
paragraphs (j)(3) and (4) of this section may be delegated to the State 
under section 114 of the CAA.
    (l)(1) A SIP revision may assign legal authority to local agencies 
in accordance with Sec. 51.232.
    (2) Each SIP revision must comply with Sec. 51.240 (regarding 
general plan requirements).
    (m) Each SIP revision must comply with Sec. 51.280 (regarding 
resources).
    (n) Each SIP revision must provide for State compliance with the 
reporting requirements in Sec. 51.125.
    (o)(1) Notwithstanding any other provision of this section, if a 
State adopts regulations substantively identical to subparts AA through 
II of part 96 of

[[Page 205]]

this chapter (CAIR NOX Annual Trading Program), incorporates 
such subparts by reference into its regulations, or adopts regulations 
that differ substantively from such subparts only as set forth in 
paragraph (o)(2) of this section, then such emissions trading program in 
the State's SIP revision is automatically approved as meeting the 
requirements of paragraph (e) of this section, provided that the State 
has the legal authority to take such action and to implement its 
responsibilities under such regulations. Before January 1, 2009, a 
State's regulations shall be considered to be substantively identical to 
subparts AA through II of part 96 of this chapter, or differing 
substantively only as set forth in paragraph (o)(2) of this section, 
regardless of whether the State's regulations include the definition of 
``Biomass'', paragraph (3) of the definition of ``Cogeneration unit'', 
and the second sentence of the definition of ``Total energy input'' in 
Sec. 96.102 of this chapter promulgated on October 19, 2007, provided 
that the State timely submits to the Administrator a SIP revision that 
revises the State's regulations to include such provisions. Submission 
to the Administrator of a SIP revision that revises the State's 
regulations to include such provisions shall be considered timely if the 
submission is made by January 1, 2009.
    (2) If a State adopts an emissions trading program that differs 
substantively from subparts AA through II of part 96 of this chapter 
only as follows, then the emissions trading program is approved as set 
forth in paragraph (o)(1) of this section.
    (i) The State may decline to adopt the CAIR NOX opt-in 
provisions of:
    (A) Subpart II of this part and the provisions applicable only to 
CAIR NOX opt-in units in subparts AA through HH of this part;
    (B) Section 96.188(b) of this chapter and the provisions of subpart 
II of this part applicable only to CAIR NOX opt-in units 
under Sec. 96.188(b); or
    (C) Section 96.188(c) of this chapter and the provisions of subpart 
II of this part applicable only to CAIR NOX opt-in units 
under Sec. 96.188(c).
    (ii) The State may decline to adopt the allocation provisions set 
forth in subpart EE of part 96 of this chapter and may instead adopt any 
methodology for allocating CAIR NOX allowances to individual 
sources, as follows:
    (A) The State's methodology must not allow the State to allocate 
CAIR NOX allowances for a year in excess of the amount in the 
State's Annual EGU NOX Budget for such year;
    (B) The State's methodology must require that, for EGUs commencing 
operation before January 1, 2001, the State will determine, and notify 
the Administrator of, each unit's allocation of CAIR NOX 
allowances by October 31, 2006 for 2009, 2010, and 2011 and by October 
31, 2008 and October 31 of each year thereafter for 4th the year after 
the year of the notification deadline;
    (C) The State's methodology must require that, for EGUs commencing 
operation on or after January 1, 2001, the State will determine, and 
notify the Administrator of, each unit's allocation of CAIR 
NOX allowances by October 31 of the year for which the CAIR 
NOX allowances are allocated; and
    (D) The State's methodology for allocating the compliance supplement 
pool must be substantively identical to Sec. 97.143 (except that the 
permitting authority makes the allocations and the Administrator records 
the allocations made by the permitting authority) or otherwise in 
accordance with paragraph (e)(4) of this section.
    (3) A State that adopts an emissions trading program in accordance 
with paragraph (o)(1) or (2) of this section is not required to adopt an 
emissions trading program in accordance with paragraph (aa)(1) or (2) of 
this section or Sec. 96.124(o)(1) or (2).
    (4) If a State adopts an emissions trading program that differs 
substantively from subparts AA through HH of part 96 of this chapter, 
other than as set forth in paragraph (o)(2) of this section, then such 
emissions trading program is not automatically approved as set forth in 
paragraph (o)(1) or (2) of this section and will be reviewed by the 
Administrator for approvability in accordance with the other provisions 
of this section, provided that the NOX allowances issued 
under such emissions trading program shall not, and the SIP revision 
shall state that such NOX allowances shall

[[Page 206]]

not, qualify as CAIR NOX allowances or CAIR NOX 
Ozone Season allowances under any emissions trading program approved 
under paragraphs (o)(1) or (2) or (aa)(1) or (2) of this section.
    (p) Notwithstanding any other provision of this section, a State may 
adopt, and include in a SIP revision submitted by March 31, 2007, 
regulations relating to the Federal CAIR NOX Annual Trading 
Program under subparts AA through HH of part 97 of this chapter as 
follows:
    (1) The State may adopt, as CAIR NOX allowance allocation 
provisions replacing the provisions in subpart EE of part 97 of this 
chapter:
    (i) Allocation provisions substantively identical to subpart EE of 
part 96 of this chapter, under which the permitting authority makes the 
allocations; or
    (ii) Any methodology for allocating CAIR NOX allowances 
to individual sources under which the permitting authority makes the 
allocations, provided that:
    (A) The State's methodology must not allow the permitting authority 
to allocate CAIR NOX allowances for a year in excess of the 
amount in the State's Annual EGU NOX budget for such year.
    (B) The State's methodology must require that, for EGUs commencing 
operation before January 1, 2001, the permitting authority will 
determine, and notify the Administrator of, each unit's allocation of 
CAIR NOX allowances by April 30, 2007 for 2009, 2010, and 
2011 and by October 31, 2008 and October 31 of each year thereafter for 
the 4th year after the year of the notification deadline.
    (C) The State's methodology must require that, for EGUs commencing 
operation on or after January 1, 2001, the permitting authority will 
determine, and notify the Administrator of, each unit's allocation of 
CAIR NOX allowances by October 31 of the year for which the 
CAIR NOX allowances are allocated.
    (2) The State may adopt, as compliance supplement pool provisions 
replacing the provisions in Sec. 97.143 of this chapter:
    (i) Provisions for allocating the State's compliance supplement pool 
that are substantively identical to Sec. 97.143 of this chapter, except 
that the permitting authority makes the allocations and the 
Administrator records the allocations made by the permitting authority;
    (ii) Provisions for allocating the State's compliance supplement 
pool that are substantively identical to Sec. 96.143 of this chapter; 
or
    (iii) Other provisions for allocating the State's compliance 
supplement pool that are in accordance with paragraph (e)(4) of this 
section.
    (3) The State may adopt CAIR opt-in unit provisions as follows:
    (i) Provisions for CAIR opt-in units, including provisions for 
applications for CAIR opt-in permits, approval of CAIR opt-in permits, 
treatment of units as CAIR opt-in units, and allocation and recordation 
of CAIR NOX allowances for CAIR opt-in units, that are 
substantively identical to subpart II of part 96 of this chapter and the 
provisions of subparts AA through HH that are applicable to CAIR opt-in 
units or units for which a CAIR opt-in permit application is submitted 
and not withdrawn and a CAIR opt-in permit is not yet issued or denied;
    (ii) Provisions for CAIR opt-in units, including provisions for 
applications for CAIR opt-in permits, approval of CAIR opt-in permits, 
treatment of units as CAIR opt-in units, and allocation and recordation 
of CAIR NOX allowances for CAIR opt-in units, that are 
substantively identical to subpart II of part 96 of this chapter and the 
provisions of subparts AA through HH that are applicable to CAIR opt-in 
units or units for which a CAIR opt-in permit application is submitted 
and not withdrawn and a CAIR opt-in permit is not yet issued or denied, 
except that the provisions exclude Sec. 96.188(b) of this chapter and 
the provisions of subpart II of part 96 of this chapter that apply only 
to units covered by Sec. 96.188(b) of this chapter; or
    (iii) Provisions for applications for CAIR opt-in units, including 
provisions for CAIR opt-in permits, approval of CAIR opt-in permits, 
treatment of units as CAIR opt-in units, and allocation and recordation 
of CAIR NOX allowances for CAIR opt-in units, that are 
substantively identical to subpart

[[Page 207]]

II of part 96 of this chapter and the provisions of subparts AA through 
HH that are applicable to CAIR opt-in units or units for which a CAIR 
opt-in permit application is submitted and not withdrawn and a CAIR opt-
in permit is not yet issued or denied, except that the provisions 
exclude Sec. 96.188(c) of this chapter and the provisions of subpart II 
of part 96 of this chapter that apply only to units covered by Sec. 
96.188(c) of this chapter.
    (q) The State's SIP revision shall contain control measures and 
demonstrate that they will result in compliance with the State's Ozone 
Season EGU NOX Budget, if applicable, and achieve the State's 
Ozone Season Non-EGU NOX Reduction Requirement, if 
applicable, for the appropriate periods. The amounts of the State's 
Ozone Season EGU NOX Budget and Ozone Season Non-EGU 
NOX Reduction Requirement shall be determined as follows:
    (1)(i) The Ozone Season EGU NOX Budget for the State is 
defined as the total amount of NOX emissions from all EGUs in 
that State for an ozone season, if the State meets the requirements of 
paragraph (a)(2) of this section by imposing control measures, at least 
in part, on EGUs. If the State imposes control measures under this 
section on only EGUs, the Ozone Season EGU NOX Budget for the 
State shall not exceed the amount, during the indicated periods, 
specified in paragraph (q)(2) of this section.
    (ii) The Ozone Season Non-EGU NOX Reduction Requirement, 
if applicable, is defined as the total amount of NOX emission 
reductions that the State demonstrates, in accordance with paragraph (s) 
of this section, it will achieve from non-EGUs during the appropriate 
period. If the State meets the requirements of paragraph (a)(2) of this 
section by imposing control measures on only non-EGUs, then the State's 
Ozone Season Non-EGU NOX Reduction Requirement shall equal or 
exceed, during the appropriate periods, the amount determined in 
accordance with paragraph (q)(3) of this section.
    (iii) If a State meets the requirements of paragraph (a)(2) of this 
section by imposing control measures on both EGUs and non-EGUs, then:
    (A) The Ozone Season Non-EGU NOX Reduction Requirement 
shall equal or exceed the difference between the amount specified in 
paragraph (q)(2) of this section for the appropriate period and the 
amount of the State's Ozone Season EGU NOX Budget specified 
in the SIP revision for the appropriate period; and
    (B) The Ozone Season EGU NOX Budget shall not exceed, 
during the indicated periods, the amount specified in paragraph (q)(2) 
of this section plus the amount of the Ozone Season Non-EGU 
NOX Reduction Requirement under paragraph (q)(1)(iii)(A) of 
this section for the appropriate period.
    (2) For a State that complies with the requirements of paragraph 
(a)(2) of this section by imposing control measures on only EGUs, the 
amount of the Ozone Season EGU NOX Budget, in tons of 
NOX per ozone season, shall be as follows, for the indicated 
State for the indicated period:

------------------------------------------------------------------------
                                                           Ozone season
                                           Ozone season   EGU NOX budget
                  State                   EGU NOX budget   for 2015 and
                                           for 2009-2014    thereafter
                                              (tons)          (tons)
------------------------------------------------------------------------
Alabama.................................          32,182          26,818
Arkansas................................          11,515           9,596
Connecticut.............................           2,559           2,559
Delaware................................           2,226           1,855
District of Columbia....................             112              94
Florida.................................          47,912          39,926
Illinois................................          30,701          28,981
Indiana.................................          45,952          39,273
Iowa....................................          14,263          11,886
Kentucky................................          36,045          30,587
Louisiana...............................          17,085          14,238
Maryland................................          12,834          10,695
Massachusetts...........................           7,551           6,293
Michigan................................          28,971          24,142
Mississippi.............................           8,714           7,262
Missouri................................          26,678          22,231
New Jersey..............................           6,654           5,545
New York................................          20,632          17,193
North Carolina..........................          28,392          23,660
Ohio....................................          45,664          39,945
Pennsylvania............................          42,171          35,143
South Carolina..........................          15,249          12,707
Tennessee...............................          22,842          19,035
Virginia................................          15,994          13,328
West Virginia...........................          26,859          26,525
Wisconsin...............................          17,987          14,989
------------------------------------------------------------------------

    (3) For a State that complies with the requirements of paragraph 
(a)(2) of this section by imposing control measures on only non-EGUs, 
the amount of the Ozone Season Non-EGU NOX Reduction 
Requirement, in tons of NOX per ozone season, shall be 
determined, for the State for 2009 and thereafter, by

[[Page 208]]

subtracting the amount of the State's Ozone Season EGU NOX 
Budget for the appropriate year, specified in paragraph (q)(2) of this 
section, from the amount of the State's NOX baseline EGU 
emissions inventory projected for the ozone season in the appropriate 
year, specified in Table 7 of ``Regional and State SO2 and 
NOX Budgets'', March 2005 (available at: http://www.epa.gov/
cleanairinterstaterule).
    (4) Notwithstanding the State's obligation to comply with paragraph 
(q)(2) or (3) of this section, the State's SIP revision may allow 
sources required by the revision to implement NOX emission 
control measures to demonstrate compliance using NOX SIP Call 
allowances allocated under the NOX Budget Trading Program for 
any ozone season during 2003 through 2008 that have not been deducted by 
the Administrator under the NOX Budget Trading Program, if 
the SIP revision ensures that such allowances will not be available for 
such deduction under the NOX Budget Trading Program.
    (r) Each SIP revision must set forth control measures to meet the 
amounts specified in paragraph (q) of this section, as applicable, 
including the following:
    (1) A description of enforcement methods including, but not limited 
to:
    (i) Procedures for monitoring compliance with each of the selected 
control measures;
    (ii) Procedures for handling violations; and
    (iii) A designation of agency responsibility for enforcement of 
implementation.
    (2)(i) If a State elects to impose control measures on EGUs, then 
those measures must impose an ozone season NOX mass emissions 
cap on all such sources in the State.
    (ii) If a State elects to impose control measures on fossil fuel-
fired non-EGUs that are boilers or combustion turbines with a maximum 
design heat input greater than 250 mmBtu/hr, then those measures must 
impose an ozone season NOX mass emissions cap on all such 
sources in the State.
    (iii) If a State elects to impose control measures on non-EGUs other 
than those described in paragraph (r)(2)(ii) of this section, then those 
measures must impose an ozone season NOX mass emissions cap 
on all such sources in the State or the State must demonstrate why such 
emissions cap is not practicable and adopt alternative requirements that 
ensure that the State will comply with its requirements under paragraph 
(q) of this section, as applicable, in 2009 and subsequent years.
    (s)(1) Each SIP revision that contains control measures covering 
non-EGUs as part or all of a State's obligation in meeting its 
requirement under paragraph (a)(2) of this section must demonstrate that 
such control measures are adequate to provide for the timely compliance 
with the State's Ozone Season Non-EGU NOX Reduction 
Requirement under paragraph (q) of this section and are not adopted or 
implemented by the State, as of May 12, 2005, and are not adopted or 
implemented by the federal government, as of the date of submission of 
the SIP revision by the State to EPA.
    (2) The demonstration under paragraph (s)(1) of this section must 
include the following, with respect to each source category of non-EGUs 
for which the SIP revision requires control measures:
    (i) A detailed historical baseline inventory of NOX mass 
emissions from the source category in a representative ozone season 
consisting, at the State's election, of the ozone season in 2002, 2003, 
2004, or 2005, or an average of 2 or more of those ozone seasons, absent 
the control measures specified in the SIP revision.
    (A) This inventory must represent estimates of actual emissions 
based on monitoring data in accordance with subpart H of part 75 of this 
chapter, if the source category is subject to monitoring requirements in 
accordance with subpart H of part 75 of this chapter.
    (B) In the absence of monitoring data in accordance with subpart H 
of part 75 of this chapter, actual emissions must be quantified, to the 
maximum extent practicable, with the same degree of assurance with which 
emissions are quantified for sources subject to subpart H of part 75 of 
this chapter and using source-specific or source-category-specific 
assumptions that ensure a source's or source category's actual

[[Page 209]]

emissions are not overestimated. If a State uses factors to estimate 
emissions, production or utilization, or effectiveness of controls or 
rules for a source category, such factors must be chosen to ensure that 
emissions are not overestimated.
    (C) For measures to reduce emissions from motor vehicles, emission 
estimates must be based on an emissions model that has been approved by 
EPA for use in SIP development and must be consistent with the planning 
assumptions regarding vehicle miles traveled and other factors current 
at the time of the SIP development.
    (D) For measures to reduce emissions from nonroad engines or 
vehicles, emission estimates methodologies must be approved by EPA.
    (ii) A detailed baseline inventory of NOX mass emissions 
from the source category in ozone seasons 2009 and 2015, absent the 
control measures specified in the SIP revision and reflecting changes in 
these emissions from the historical baseline ozone season to the ozone 
seasons 2009 and 2015, based on projected changes in the production 
input or output, population, vehicle miles traveled, economic activity, 
or other factors as applicable to this source category.
    (A) These inventories must account for implementation of any control 
measures that are adopted or implemented by the State, as of May 12, 
2005, or adopted or implemented by the federal government, as of the 
date of submission of the SIP revision by the State to EPA, and must 
exclude any control measures specified in the SIP revision to meet the 
NOX emissions reduction requirements of this section.
    (B) Economic and population forecasts must be as specific as 
possible to the applicable industry, State, and county of the source or 
source category and must be consistent with both national projections 
and relevant official planning assumptions including estimates of 
population and vehicle miles traveled developed through consultation 
between State and local transportation and air quality agencies. 
However, if these official planning assumptions are inconsistent with 
official U.S. Census projections of population or with energy 
consumption projections contained in the U.S. Department of Energy's 
most recent Annual Energy Outlook, then the SIP revision must make 
adjustments to correct the inconsistency or must demonstrate how the 
official planning assumptions are more accurate.
    (C) These inventories must account for any changes in production 
method, materials, fuels, or efficiency that are expected to occur 
between the historical baseline ozone season and ozone season 2009 or 
ozone season 2015, as appropriate.
    (iii) A projection of NOX mass emissions in ozone season 
2009 and ozone season 2015 from the source category assuming the same 
projected changes as under paragraph (s)(2)(ii) of this section and 
resulting from implementation of each of the control measures specified 
in the SIP revision.
    (A) These inventories must address the possibility that the State's 
new control measures may cause production or utilization, and emissions, 
to shift to unregulated or less stringently regulated sources in the 
source category in the same or another State, and these inventories must 
include any such amounts of emissions that may shift to such other 
sources.
    (B) The State must provide EPA with a summary of the computations, 
assumptions, and judgments used to determine the degree of reduction in 
projected ozone season 2009 and ozone season 2015 NOX 
emissions that will be achieved from the implementation of the new 
control measures compared to the relevant baseline emissions inventory.
    (iv) The result of subtracting the amounts in paragraph (s)(2)(iii) 
of this section for ozone season 2009 and ozone season 2015, 
respectively, from the lower of the amounts in paragraph (s)(2)(i) or 
(s)(2)(ii) of this section for ozone season 2009 and ozone season 2015, 
respectively, may be credited towards the State's Ozone Season Non-EGU 
NOX Reduction Requirement in paragraph (q)(3) of this section 
for the appropriate period.
    (v) Each SIP revision must identify the sources of the data used in 
each estimate and each projection of emissions.

[[Page 210]]

    (t) Each SIP revision must comply with Sec. 51.116 (regarding data 
availability).
    (u) Each SIP revision must provide for monitoring the status of 
compliance with any control measures adopted to meet the State's 
requirements under paragraph (q) of this section as follows:
    (1) The SIP revision must provide for legally enforceable procedures 
for requiring owners or operators of stationary sources to maintain 
records of, and periodically report to the State:
    (i) Information on the amount of NOX emissions from the 
stationary sources; and
    (ii) Other information as may be necessary to enable the State to 
determine whether the sources are in compliance with applicable portions 
of the control measures;
    (2) The SIP revision must comply with Sec. 51.212 (regarding 
testing, inspection, enforcement, and complaints);
    (3) If the SIP revision contains any transportation control 
measures, then the SIP revision must comply with Sec. 51.213 (regarding 
transportation control measures);
    (4)(i) If the SIP revision contains measures to control EGUs, then 
the SIP revision must require such sources to comply with the 
monitoring, recordkeeping, and reporting provisions of subpart H of part 
75 of this chapter.
    (ii) If the SIP revision contains measures to control fossil fuel-
fired non-EGUs that are boilers or combustion turbines with a maximum 
design heat input greater than 250 mmBtu/hr, then the SIP revision must 
require such sources to comply with the monitoring, recordkeeping, and 
reporting provisions of subpart H of part 75 of this chapter.
    (iii) If the SIP revision contains measures to control any other 
non-EGUs that are not described in paragraph (u)(4)(ii) of this section, 
then the SIP revision must require such sources to comply with the 
monitoring, recordkeeping, and reporting provisions of subpart H of part 
75 of this chapter, or the State must demonstrate why such requirements 
are not practicable and adopt alternative requirements that ensure that 
the required emissions reductions will be quantified, to the maximum 
extent practicable, with the same degree of assurance with which 
emissions are quantified for sources subject to subpart H of part 75 of 
this chapter.
    (v) Each SIP revision must show that the State has legal authority 
to carry out the SIP revision, including authority to:
    (1) Adopt emissions standards and limitations and any other measures 
necessary for attainment and maintenance of the State's relevant Ozone 
Season EGU NOX Budget or the Ozone Season Non-EGU 
NOX Reduction Requirement, as applicable, under paragraph (q) 
of this section;
    (2) Enforce applicable laws, regulations, and standards and seek 
injunctive relief;
    (3) Obtain information necessary to determine whether air pollution 
sources are in compliance with applicable laws, regulations, and 
standards, including authority to require recordkeeping and to make 
inspections and conduct tests of air pollution sources; and
    (4)(i) Require owners or operators of stationary sources to install, 
maintain, and use emissions monitoring devices and to make periodic 
reports to the State on the nature and amounts of emissions from such 
stationary sources; and
    (ii) Make the data described in paragraph (v)(4)(i) of this section 
available to the public within a reasonable time after being reported 
and as correlated with any applicable emissions standards or 
limitations.
    (w)(1) The provisions of law or regulation that the State determines 
provide the authorities required under this section must be specifically 
identified, and copies of such laws or regulations must be submitted 
with the SIP revision.
    (2) Legal authority adequate to fulfill the requirements of 
paragraphs (v)(3) and (4) of this section may be delegated to the State 
under section 114 of the CAA.
    (x)(1) A SIP revision may assign legal authority to local agencies 
in accordance with Sec. 51.232.
    (2) Each SIP revision must comply with Sec. 51.240 (regarding 
general plan requirements).

[[Page 211]]

    (y) Each SIP revision must comply with Sec. 51.280 (regarding 
resources).
    (z) Each SIP revision must provide for State compliance with the 
reporting requirements in Sec. 51.125.
    (aa)(1) Notwithstanding any other provision of this section, if a 
State adopts regulations substantively identical to subparts AAAA 
through IIII of part 96 of this chapter (CAIR Ozone Season 
NOX Trading Program), incorporates such subparts by reference 
into its regulations, or adopts regulations that differ substantively 
from such subparts only as set forth in paragraph (aa)(2) of this 
section, then such emissions trading program in the State's SIP revision 
is automatically approved as meeting the requirements of paragraph (q) 
of this section, provided that the State has the legal authority to take 
such action and to implement its responsibilities under such 
regulations. Before January 1, 2009, a State's regulations shall be 
considered to be substantively identical to subparts AAAA through IIII 
of part 96 of the chapter, or differing substantively only as set forth 
in paragraph (o)(2) of this section, regardless of whether the State's 
regulations include the definition of ``Biomass'', paragraph (3) of the 
definition of ``Cogeneration unit'', and the second sentence of the 
definition of ``Total energy input'' in Sec. 96.302 of this chapter 
promulgated on October 19, 2007, provided that the State timely submits 
to the Administrator a SIP revision that revises the State's regulations 
to include such provisions. Submission to the Administrator of a SIP 
revision that revises the State's regulations to include such provisions 
shall be considered timely if the submission is made by January 1, 2009.
    (2) If a State adopts an emissions trading program that differs 
substantively from subparts AAAA through IIII of part 96 of this chapter 
only as follows, then the emissions trading program is approved as set 
forth in paragraph (aa)(1) of this section.
    (i) The State may expand the applicability provisions in Sec. 
96.304 to include all non-EGUs subject to the State's emissions trading 
program approved under Sec. 51.121(p).
    (ii) The State may decline to adopt the CAIR NOX Ozone 
Season opt-in provisions of:
    (A) Subpart IIII of this part and the provisions applicable only to 
CAIR NOX Ozone Season opt-in units in subparts AAAA through 
HHHH of this part;
    (B) Section 96.388(b) of this chapter and the provisions of subpart 
IIII of this part applicable only to CAIR NOX Ozone Season 
opt-in units under Sec. 96.388(b); or
    (C) Section 96.388(c) of this chapter and the provisions of subpart 
IIII of this part applicable only to CAIR NOX Ozone Season 
opt-in units under Sec. 96.388(c).
    (iii) The State may decline to adopt the allocation provisions set 
forth in subpart EEEE of part 96 of this chapter and may instead adopt 
any methodology for allocating CAIR NOX Ozone Season 
allowances to individual sources, as follows:
    (A) The State may provide for issuance of an amount of CAIR Ozone 
Season NOX allowances for an ozone season, in addition to the 
amount in the State's Ozone Season EGU NOX Budget for such 
ozone season, not exceeding the amount of NOX SIP Call 
allowances allocated for the ozone season under the NOX 
Budget Trading Program to non-EGUs that the applicability provisions in 
Sec. 96.304 are expanded to include under paragraph (aa)(2)(i) of this 
section;
    (B) The State's methodology must not allow the State to allocate 
CAIR Ozone Season NOX allowances for an ozone season in 
excess of the amount in the State's Ozone Season EGU NOX 
Budget for such ozone season plus any additional amount of CAIR Ozone 
Season NOX allowances issued under paragraph (aa)(2)(iii)(A) 
of this section for such ozone season;
    (C) The State's methodology must require that, for EGUs commencing 
operation before January 1, 2001, the State will determine, and notify 
the Administrator of, each unit's allocation of CAIR NOX 
allowances by October 31, 2006 for the ozone seasons 2009, 2010, and 
2011 and by October 31, 2008 and October 31 of each year thereafter for 
the ozone season in the 4th year after the year of the notification 
deadline; and

[[Page 212]]

    (D) The State's methodology must require that, for EGUs commencing 
operation on or after January 1, 2001, the State will determine, and 
notify the Administrator of, each unit's allocation of CAIR Ozone Season 
NOX allowances by July 31 of the calendar year of the ozone 
season for which the CAIR Ozone Season NOX allowances are 
allocated.
    (3) A State that adopts an emissions trading program in accordance 
with paragraph (aa)(1) or (2) of this section is not required to adopt 
an emissions trading program in accordance with paragraph (o)(1) or (2) 
of this section or Sec. 51.153(o)(1) or (2).
    (4) If a State adopts an emissions trading program that differs 
substantively from subparts AAAA through IIII of part 96 of this 
chapter, other than as set forth in paragraph (aa)(2) of this section, 
then such emissions trading program is not automatically approved as set 
forth in paragraph (aa)(1) or (2) of this section and will be reviewed 
by the Administrator for approvability in accordance with the other 
provisions of this section, provided that the NOX allowances 
issued under such emissions trading program shall not, and the SIP 
revision shall state that such NOX allowances shall not, 
qualify as CAIR NOX allowances or CAIR Ozone Season 
NOX allowances under any emissions trading program approved 
under paragraphs (o)(1) or (2) or (aa)(1) or (2) of this section.
    (bb)(1)(i) The State may revise its SIP to provide that, for each 
ozone season during which a State implements control measures on EGUs or 
non-EGUs through an emissions trading program approved under paragraph 
(aa)(1) or (2) of this section, such EGUs and non-EGUs shall not be 
subject to the requirements of the State's SIP meeting the requirements 
of Sec. 51.121, if the State meets the requirement in paragraph 
(bb)(1)(ii) of this section.
    (ii) For a State under paragraph (bb)(1)(i) of this section, if the 
State's amount of tons specified in paragraph (q)(2) of this section 
exceeds the State's amount of NOX SIP Call allowances 
allocated for the ozone season in 2009 or in any year thereafter for the 
same types and sizes of units as those covered by the amount of tons 
specified in paragraph (q)(2) of this section, then the State must 
replace the former amount for such ozone season by the latter amount for 
such ozone season in applying paragraph (q) of this section.
    (2) Rhode Island may revise its SIP to provide that, for each ozone 
season during which Rhode Island implements control measures on EGUs and 
non-EGUs through an emissions trading program adopted in regulations 
that differ substantively from subparts AAAA through IIII of part 96 of 
this chapter as set forth in this paragraph, such EGUs and non-EGUs 
shall not be subject to the requirements of the State's SIP meeting the 
requirements of Sec. 51.121.
    (i) Rhode Island must expand the applicability provisions in Sec. 
96.304 to include all non-EGUs subject to Rhode Island's emissions 
trading program approved under Sec. 51.121(p).
    (ii) Rhode Island may decline to adopt the CAIR NOX Ozone 
Season opt-in provisions of:
    (A) Subpart IIII of this part and the provisions applicable only to 
CAIR NOX Ozone Season opt-in units in subparts AAAA through 
HHHH of this part;
    (B) Section 96.388(b) of this chapter and the provisions of subpart 
IIII of this part applicable only to CAIR NOX Ozone Season 
opt-in units under Sec. 96.388(b); or
    (C) Section 96.388(c) of this chapter and the provisions of subpart 
IIII of this part applicable only to CAIR NOX Ozone Season 
opt-in units under Sec. 96.388(c).
    (iii) Rhode Island may adopt the allocation provisions set forth in 
subpart EEEE of part 96 of this chapter, provided that Rhode Island must 
provide for issuance of an amount of CAIR Ozone Season NOX 
allowances for an ozone season not exceeding 936 tons for 2009 and 
thereafter;
    (iv) Rhode Island may adopt any methodology for allocating CAIR 
NOX Ozone Season allowances to individual sources, as 
follows:
    (A) Rhode Island's methodology must not allow Rhode Island to 
allocate CAIR Ozone Season NOX allowances for an ozone season 
in excess of 936 tons for 2009 and thereafter;

[[Page 213]]

    (B) Rhode Island's methodology must require that, for EGUs 
commencing operation before January 1, 2001, Rhode Island will 
determine, and notify the Administrator of, each unit's allocation of 
CAIR NOX allowances by October 31, 2006 for the ozone seasons 
2009, 2010, and 2011 and by October 31, 2008 and October 31 of each year 
thereafter for the ozone season in the 4th year after the year of the 
notification deadline; and
    (C) Rhode Island's methodology must require that, for EGUs 
commencing operation on or after January 1, 2001, Rhode Island will 
determine, and notify the Administrator of, each unit's allocation of 
CAIR Ozone Season NOX allowances by July 31 of the calendar 
year of the ozone season for which the CAIR Ozone Season NOX 
allowances are allocated.
    (3) Notwithstanding a SIP revision by a State authorized under 
paragraph (bb)(1) of this section or by Rhode Island under paragraph 
(bb)(2) of this section, if the State's or Rhode Island's SIP that, 
without such SIP revision, imposes control measures on EGUs or non-EGUs 
under Sec. 51.121 is determined by the Administrator to meet the 
requirements of Sec. 51.121, such SIP shall be deemed to continue to 
meet the requirements of Sec. 51.121.
    (cc) The terms used in this section shall have the following 
meanings:
    Administrator means the Administrator of the United States 
Environmental Protection Agency or the Administrator's duly authorized 
representative.
    Allocate or allocation means, with regard to allowances, the 
determination of the amount of allowances to be initially credited to a 
source or other entity.
    Biomass means--
    (1) Any organic material grown for the purpose of being converted to 
energy;
    (2) Any organic byproduct of agriculture that can be converted into 
energy; or
    (3) Any material that can be converted into energy and is 
nonmerchantable for other purposes, that is segregated from other 
nonmerchantable material, and that is;
    (i) A forest-related organic resource, including mill residues, 
precommercial thinnings, slash, brush, or byproduct from conversion of 
trees to merchantable material; or
    (ii) A wood material, including pallets, crates, dunnage, 
manufacturing and construction materials (other than pressure-treated, 
chemically-treated, or painted wood products), and landscape or right-
of-way tree trimmings.
    Boiler means an enclosed fossil- or other-fuel-fired combustion 
device used to produce heat and to transfer heat to recirculating water, 
steam, or other medium.
    Bottoming-cycle cogeneration unit means a cogeneration unit in which 
the energy input to the unit is first used to produce useful thermal 
energy and at least some of the reject heat from the useful thermal 
energy application or process is then used for electricity production.
    Clean Air Act or CAA means the Clean Air Act, 42 U.S.C. 7401, et 
seq.
    Cogeneration unit means a stationary, fossil-fuel-fired boiler or 
stationary, fossil-fuel-fired combustion turbine:
    (1) Having equipment used to produce electricity and useful thermal 
energy for industrial, commercial, heating, or cooling purposes through 
the sequential use of energy; and
    (2) Producing during the 12-month period starting on the date the 
unit first produces electricity and during any calendar year after the 
calendar year in which the unit first produces electricity--
    (i) For a topping-cycle cogeneration unit,
    (A) Useful thermal energy not less than 5 percent of total energy 
output; and
    (B) Useful power that, when added to one-half of useful thermal 
energy produced, is not less then 42.5 percent of total energy input, if 
useful thermal energy produced is 15 percent or more of total energy 
output, or not less than 45 percent of total energy input, if useful 
thermal energy produced is less than 15 percent of total energy output.
    (ii) For a bottoming-cycle cogeneration unit, useful power not less 
than 45 percent of total energy input;
    (3) Provided that the total energy input under paragraphs (2)(i)(B) 
and

[[Page 214]]

(2)(ii) of this definition shall equal the unit's total energy input 
from all fuel except biomass if the unit is a boiler.
    Combustion turbine means:
    (1) An enclosed device comprising a compressor, a combustor, and a 
turbine and in which the flue gas resulting from the combustion of fuel 
in the combustor passes through the turbine, rotating the turbine; and
    (2) If the enclosed device under paragraph (1) of this definition is 
combined cycle, any associated duct burner, heat recovery steam 
generator, and steam turbine.
    Commence operation means to have begun any mechanical, chemical, or 
electronic process, including, with regard to a unit, start-up of a 
unit's combustion chamber.
    Electric generating unit or EGU means:
    (1)(i) Except as provided in paragraph (2) of this definition, a 
stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired 
combustion turbine serving at any time, since the later of November 15, 
1990 or the start-up of the unit's combustion chamber, a generator with 
nameplate capacity of more than 25 MWe producing electricity for sale.
    (ii) If a stationary boiler or stationary combustion turbine that, 
under paragraph (1)(i) of this section, is not an electric generating 
unit begins to combust fossil fuel or to serve a generator with 
nameplate capacity of more than 25 MWe producing electricity for sale, 
the unit shall become an electric generating unit as provided in 
paragraph (1)(i) of this section on the first date on which it both 
combusts fossil fuel and serves such generator.
    (2) A unit that meets the requirements set forth in paragraphs 
(2)(i)(A), (2)(ii)(A), or (2)(ii)(B) of this definition paragraph shall 
not be an electric generating unit:
    (i)(A) Any unit that is an electric generating unit under paragraph 
(1)(i) or (ii) of this definition:
    (1) Qualifying as a cogeneration unit during the 12-month period 
starting on the date the unit first produces electricity and continuing 
to qualify as a cogeneration unit; and
    (2) Not serving at any time, since the later of November 15, 1990 or 
the start-up of the unit's combustion chamber, a generator with 
nameplate capacity of more than 25 MWe supplying in any calendar year 
more than one-third of the unit's potential electric output capacity or 
219,000 MWh, whichever is greater, to any utility power distribution 
system for sale.
    (B) If a unit qualifies as a cogeneration unit during the 12-month 
period starting on the date the unit first produces electricity and 
meets the requirements of paragraphs (2)(i)(A) of this section for at 
least one calendar year, but subsequently no longer meets all such 
requirements, the unit shall become an electric generating unit starting 
on the earlier of January 1 after the first calendar year during which 
the unit first no longer qualifies as a cogeneration unit or January 1 
after the first calendar year during which the unit no longer meets the 
requirements of paragraph (2)(i)(A)(2) of this section.
    (ii)(A) Any unit that is an electric generating unit under paragraph 
(1)(i) or (ii) of this definition commencing operation before January 1, 
1985:
    (1) Qualifying as a solid waste incineration unit; and
    (2) With an average annual fuel consumption of non-fossil fuel for 
1985-1987 exceeding 80 percent (on a Btu basis) and an average annual 
fuel consumption of non-fossil fuel for any 3 consecutive calendar years 
after 1990 exceeding 80 percent (on a Btu basis).
    (B) Any unit that is an electric generating unit under paragraph 
(1)(i) or (ii) of this definition commencing operation on or after 
January 1, 1985:
    (1) Qualifying as a solid waste incineration unit; and
    (2) With an average annual fuel consumption of non-fossil fuel for 
the first 3 calendar years of operation exceeding 80 percent (on a Btu 
basis) and an average annual fuel consumption of non-fossil fuel for any 
3 consecutive calendar years after 1990 exceeding 80 percent (on a Btu 
basis).
    (C) If a unit qualifies as a solid waste incineration unit and meets 
the requirements of paragraph (2)(ii)(A) or (B) of this section for at 
least 3 consecutive calendar years, but subsequently no longer meets all 
such requirements, the unit shall become an electric generating unit 
starting on the

[[Page 215]]

earlier of January 1 after the first calendar year during which the unit 
first no longer qualifies as a solid waste incineration unit or January 
1 after the first 3 consecutive calendar years after 1990 for which the 
unit has an average annual fuel consumption of fossil fuel of 20 percent 
or more.
    Fossil fuel means natural gas, petroleum, coal, or any form of 
solid, liquid, or gaseous fuel derived from such material.
    Fossil-fuel-fired means, with regard to a unit, combusting any 
amount of fossil fuel in any calendar year.
    Generator means a device that produces electricity.
    Maximum design heat input means the maximum amount of fuel per hour 
(in Btu/hr) that a unit is capable of combusting on a steady state basis 
as of the initial installation of the unit as specified by the 
manufacturer of the unit.
    NAAQS means National Ambient Air Quality Standard.
    Nameplate capacity means, starting from the initial installation of 
a generator, the maximum electrical generating output (in MWe) that the 
generator is capable of producing on a steady state basis and during 
continuous operation (when not restricted by seasonal or other 
deratings) as of such installation as specified by the manufacturer of 
the generator or, starting from the completion of any subsequent 
physical change in the generator resulting in an increase in the maximum 
electrical generating output (in MWe) that the generator is capable of 
producing on a steady state basis and during continuous operation (when 
not restricted by seasonal or other deratings), such increased maximum 
amount as of such completion as specified by the person conducting the 
physical change.
    Non-EGU means a source of NOX emissions that is not an 
EGU.
    NOX Budget Trading Program means a multi-state nitrogen 
oxides air pollution control and emission reduction program approved and 
administered by the Administrator in accordance with subparts A through 
I of this part and Sec. 51.121, as a means of mitigating interstate 
transport of ozone and nitrogen oxides.
    NOX SIP Call allowance means a limited authorization 
issued by the Administrator under the NOX Budget Trading 
Program to emit up to one ton of nitrogen oxides during the ozone season 
of the specified year or any year thereafter, provided that the 
provision in Sec. 51.121(b)(2)(ii)(E) shall not be used in applying 
this definition.
    Ozone season means the period, which begins May 1 and ends September 
30 of any year.
    Potential electrical output capacity means 33 percent of a unit's 
maximum design heat input, divided by 3,413 Btu/kWh, divided by 1,000 
kWh/MWh, and multiplied by 8,760 hr/yr.
    Sequential use of energy means:
    (1) For a topping-cycle cogeneration unit, the use of reject heat 
from electricity production in a useful thermal energy application or 
process; or
    (2) For a bottoming-cycle cogeneration unit, the use of reject heat 
from useful thermal energy application or process in electricity 
production.
    Solid waste incineration unit means a stationary, fossil-fuel-fired 
boiler or stationary, fossil-fuel-fired combustion turbine that is a 
``solid waste incineration unit'' as defined in section 129(g)(1) of the 
Clean Air Act.
    Topping-cycle cogeneration unit means a cogeneration unit in which 
the energy input to the unit is first used to produce useful power, 
including electricity, and at least some of the reject heat from the 
electricity production is then used to provide useful thermal energy.
    Total energy input means, with regard to a cogeneration unit, total 
energy of all forms supplied to the cogeneration unit, excluding energy 
produced by the cogeneration unit itself. Each form of energy supplied 
shall be measured by the lower heating value of that form of energy 
calculated as follows:

LHV = HHV - 10.55(W + 9H)

Where:

LHV = lower heating value of fuel in Btu/lb,
HHV = higher heating value of fuel in Btu/lb,
W = Weight % of moisture in fuel, and
H = Weight % of hydrogen in fuel.

    Total energy output means, with regard to a cogeneration unit, the 
sum of useful power and useful thermal energy produced by the 
cogeneration unit.

[[Page 216]]

    Unit means a stationary, fossil-fuel-fired boiler or a stationary, 
fossil-fuel-fired combustion turbine.
    Useful power means, with regard to a cogeneration unit, electricity 
or mechanical energy made available for use, excluding any such energy 
used in the power production process (which process includes, but is not 
limited to, any on-site processing or treatment of fuel combusted at the 
unit and any on-site emission controls).
    Useful thermal energy means, with regard to a cogeneration unit, 
thermal energy that is:
    (1) Made available to an industrial or commercial process, excluding 
any heat contained in condensate return or makeup water;
    (2) Used in a heating application (e.g., space heating or domestic 
hot water heating); or
    (3) Used in a space cooling application (i.e., thermal energy used 
by an absorption chiller).
    Utility power distribution system means the portion of an 
electricity grid owned or operated by a utility and dedicated to 
delivering electricity to customers.
    (dd) New Hampshire may revise its SIP to implements control measures 
on EGUs and non-EGUs through an emissions trading program adopted in 
regulations that differ substantively from subparts AAAA through IIII of 
part 96 of this chapter as set forth in this paragraph.
    (1) New Hampshire must expand the applicability provisions in Sec. 
96.304 of this chapter to include all non-EGUs subject to New 
Hampshire's emissions trading program at New Hampshire Code of 
Administrative Rules, chapter Env-A 3200 (2004).
    (2) New Hampshire may decline to adopt the CAIR NOX Ozone 
Season opt-in provisions of:
    (i) Subpart IIII of this part and the provisions applicable only to 
CAIR NOX Ozone Season opt-in units in subparts AAAA through 
HHHH of this part;
    (ii) Section 96.388(b) of this chapter and the provisions of subpart 
IIII of this part applicable only to CAIR NOX Ozone Season 
opt-in units under Sec. 96.388(b); or
    (iii) Section 96.388(c) of this chapter and the provisions of 
subpart IIII of this part applicable only to CAIR NOX Ozone 
Season opt-in units under Sec. 96.388(c).
    (3) New Hampshire may adopt the allocation provisions set forth in 
subpart EEEE of part 96 of this chapter, provided that New Hampshire 
must provide for issuance of an amount of CAIR Ozone Season 
NOX allowances for an ozone season not exceeding 3,000 tons 
for 2009 and thereafter;
    (4) New Hampshire may adopt any methodology for allocating CAIR 
NOX Ozone Season allowances to individual sources, as 
follows:
    (i) New Hampshire's methodology must not allow New Hampshire to 
allocate CAIR Ozone Season NOX allowances for an ozone season 
in excess of 3,000 tons for 2009 and thereafter;
    (ii) New Hampshire's methodology must require that, for EGUs 
commencing operation before January 1, 2001, New Hampshire will 
determine, and notify the Administrator of, each unit's allocation of 
CAIR NOX allowances by October 31, 2006 for the ozone seasons 
2009, 2010, and 2011 and by October 31, 2008 and October 31 of each year 
thereafter for the ozone season in the 4th year after the year of the 
notification deadline; and
    (iii) New Hampshire's methodology must require that, for EGUs 
commencing operation on or after January 1, 2001, New Hampshire will 
determine, and notify the Administrator of, each unit's allocation of 
CAIR Ozone Season NOX allowances by July 31 of the calendar 
year of the ozone season for which the CAIR Ozone Season NOX 
allowances are allocated.
    (ee) Notwithstanding any other provision of this section, a State 
may adopt, and include in a SIP revision submitted by March 31, 2007, 
regulations relating to the Federal CAIR NOX Ozone Season 
Trading Program under subparts AAAA through HHHH of part 97 of this 
chapter as follows:
    (1) The State may adopt, as applicability provisions replacing the 
provisions in Sec. 97.304 of this chapter, provisions for applicability 
that are substantively identical to the provisions in Sec. 96.304 of 
this chapter expanded to include all non-EGUs subject to the State's 
emissions trading program approved under Sec. 51.121(p). Before January

[[Page 217]]

1, 2009, a State's applicability provisions shall be considered to be 
substantively identical to Sec. 96.304 of this chapter (with the 
expansion allowed under this paragraph) regardless of whether the 
State's regulations include the definition of ``Biomass'', paragraph (3) 
of the definition of ``Cogeneration unit'', and the second sentence of 
the definition of ``Total energy input'' in Sec. 97.102 of this chapter 
promulgated on October 19, 2007, provided that the State timely submits 
to the Administrator a SIP revision that revises the State's regulations 
to include such provisions. Submission to the Administrator of a SIP 
revision that revises the State's regulations to include such provisions 
shall be considered timely if the submission is made by January 1, 2009.
    (2) The State may adopt, as CAIR NOX Ozone Season 
allowance allocation provisions replacing the provisions in subpart EEEE 
of part 97 of this chapter:
    (i) Allocation provisions substantively identical to subpart EEEE of 
part 96 of this chapter, under which the permitting authority makes the 
allocations; or
    (ii) Any methodology for allocating CAIR NOX Ozone Season 
allowances to individual sources under which the permitting authority 
makes the allocations, provided that:
    (A) The State may provide for issuance of an amount of CAIR Ozone 
Season NOX allowances for an ozone season, in addition to the 
amount in the State's Ozone Season EGU NOX Budget for such 
ozone season, not exceeding the portion of the State's trading program 
budget, under the State's emissions trading program approved under Sec. 
51.121(p), attributed to the non-EGUs that the applicability provisions 
in Sec. 96.304 of this chapter are expanded to include under paragraph 
(ee)(1) of this section.
    (B) The State's methodology must not allow the State to allocate 
CAIR Ozone Season NOX allowances for an ozone season in 
excess of the amount in the State's Ozone Season EGU NOX 
Budget for such ozone season plus any additional amount of CAIR Ozone 
Season NOX allowances issued under paragraph (ee)(2)(ii)(A) 
of this section for such ozone season.
    (C) The State's methodology must require that, for EGUs commencing 
operation before January 1, 2001, the permitting authority will 
determine, and notify the Administrator of, each unit's allocation of 
CAIR NOX Ozone Season allowances by April 30, 2007 for 2009, 
2010, and 2011 and by October 31, 2008 and October 31 of each year 
thereafter for the 4th year after the year of the notification deadline.
    (D) The State's methodology must require that, for EGUs commencing 
operation on or after January 1, 2001, the permitting authority will 
determine, and notify the Administrator of, each unit's allocation of 
CAIR NOX Ozone Season allowances by July 31 of the year for 
which the CAIR NOX Ozone Season allowances are allocated.
    (3) The State may adopt CAIR opt-in unit provisions as follows:
    (i) Provisions for CAIR opt-in units, including provisions for 
applications for CAIR opt-in permits, approval of CAIR opt-in permits, 
treatment of units as CAIR opt-in units, and allocation and recordation 
of CAIR NOX Ozone Season allowances for CAIR opt-in units, 
that are substantively identical to subpart IIII of part 96 of this 
chapter and the provisions of subparts AAAA through HHHH that are 
applicable to CAIR opt-in units or units for which a CAIR opt-in permit 
application is submitted and not withdrawn and a CAIR opt-in permit is 
not yet issued or denied;
    (ii) Provisions for CAIR opt-in units, including provisions for 
applications for CAIR opt-in permits, approval of CAIR opt-in permits, 
treatment of units as CAIR opt-in units, and allocation and recordation 
of CAIR NOX Ozone Season allowances for CAIR opt-in units, 
that are substantively identical to subpart IIII of part 96 of this 
chapter and the provisions of subparts AAAA through HHHH that are 
applicable to CAIR opt-in units or units for which a CAIR opt-in permit 
application is submitted and not withdrawn and a CAIR opt-in permit is 
not yet issued or denied, except that the provisions exclude Sec. 
96.388(b) of this chapter and the provisions of subpart IIII of part 96 
of

[[Page 218]]

this chapter that apply only to units covered by Sec. 96.388(b) of this 
chapter; or
    (iii) Provisions for applications for CAIR opt-in units, including 
provisions for CAIR opt-in permits, approval of CAIR opt-in permits, 
treatment of units as CAIR opt-in units, and allocation and recordation 
of CAIR NOX allowances for CAIR opt-in units, that are 
substantively identical to subpart IIII of part 96 of this chapter and 
the provisions of subparts AAAA through HHHH that are applicable to CAIR 
opt-in units or units for which a CAIR opt-in permit application is 
submitted and not withdrawn and a CAIR opt-in permit is not yet issued 
or denied, except that the provisions exclude Sec. 96.388(c) of this 
chapter and the provisions of subpart IIII of part 96 of this chapter 
that apply only to units covered by Sec. 96.388(c) of this chapter.
    (ff) Notwithstanding any provisions of paragraphs (a) through (ee) 
of this section, subparts AA through II and AAAA through IIII of part 96 
of this chapter, subparts AA through II and AAAA through IIII of part 97 
of this chapter, and any State's SIP to the contrary:
    (1) With regard to any control period that begins after December 31, 
2014, the Administrator:
    (i) Rescinds the determination in paragraph (a) of this section that 
the States identified in paragraph (c) of this section must submit a SIP 
revision with respect to the fine particles (PM2.5) NAAQS and 
the 8-hour ozone NAAQS meeting the requirements of paragraphs (b) 
through (ee) of this section; and
    (ii) Will not carry out any of the functions set forth for the 
Administrator in subparts AA through II and AAAA through IIII of part 96 
of this chapter, subparts AA through II and AAAA through IIII of part 97 
of this chapter, or in any emissions trading program provisions in a 
State's SIP approved under this section;
    (2) The Administrator will not deduct for excess emissions any CAIR 
NOX allowances or CAIR NOX Ozone Season allowances 
allocated for 2015 or any year thereafter;
    (3) By March 3, 2015, the Administrator will remove from the CAIR 
NOX Allowance Tracking System accounts all CAIR 
NOX allowances allocated for a control period in 2015 and any 
subsequent year, and, thereafter, no holding or surrender of CAIR 
NOX allowances will be required with regard to emissions or 
excess emissions for such control periods; and
    (4) By March 3, 2015, the Administrator will remove from the CAIR 
NOX Ozone Season Allowance Tracking System accounts all CAIR 
NOX Ozone Season allowances allocated for a control period in 
2015 and any subsequent year, and, thereafter, no holding or surrender 
of CAIR NOX Ozone Season allowances will be required with 
regard to emissions or excess emissions for such control periods.

[70 FR 25319, May 12, 2005, as amended at 71 FR 25301, 25370, Apr. 28, 
2006; 71 FR 74793, Dec. 13, 2006; 72 FR 59203, Oct. 19, 2007; 74 FR 
56726, Nov. 3, 2009; 76 FR 48353, Aug. 8, 2011; 79 FR 71671, Dec. 3, 
2014]



Sec. 51.124  Findings and requirements for submission of State 
implementation plan revisions relating to emissions of sulfur dioxide 
pursuant to the Clean Air Interstate Rule.
          

    (a)(1) Under section 110(a)(1) of the CAA, 42 U.S.C. 7410(a)(1), the 
Administrator determines that each State identified in paragraph (c) of 
this section must submit a SIP revision to comply with the requirements 
of section 110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), 
through the adoption of adequate provisions prohibiting sources and 
other activities from emitting SO2 in amounts that will 
contribute significantly to nonattainment in, or interfere with 
maintenance by, one or more other States with respect to the fine 
particles (PM2.5) NAAQS.
    (2) Notwithstanding the other provisions of this section, such 
provisions are not applicable as they relate to the State of Minnesota 
as of December 3, 2009.
    (b) For each State identified in paragraph (c) of this section, the 
SIP revision required under paragraph (a) of this section will contain 
adequate provisions, for purposes of complying with section 
110(a)(2)(D)(i)(I) of the CAA, 42 U.S.C. 7410(a)(2)(D)(i)(I), only if 
the SIP revision contains control measures that assure compliance with 
the applicable requirements of this section.

[[Page 219]]

    (c) The following States are subject to the requirements of this 
section: Alabama, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, 
Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, 
Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, 
South Carolina, Tennessee, Texas, Virginia, West Virginia, Wisconsin, 
and the District of Columbia.
    (d)(1) The SIP revision under paragraph (a) of this section must be 
submitted to EPA by no later than September 11, 2006.
    (2) The requirements of appendix V to this part shall apply to the 
SIP revision under paragraph (a) of this section.
    (3) The State shall deliver 5 copies of the SIP revision under 
paragraph (a) of this section to the appropriate Regional Office, with a 
letter giving notice of such action.
    (e) The State's SIP revision shall contain control measures and 
demonstrate that they will result in compliance with the State's Annual 
EGU SO2 Budget, if applicable, and achieve the State's Annual 
Non-EGU SO2 Reduction Requirement, if applicable, for the 
appropriate periods. The amounts of the State's Annual EGU 
SO2 Budget and Annual Non-EGU SO2 Reduction 
Requirement shall be determined as follows:
    (1)(i) The Annual EGU SO2 Budget for the State is defined 
as the total amount of SO2 emissions from all EGUs in that 
State for a year, if the State meets the requirements of paragraph (a) 
of this section by imposing control measures, at least in part, on EGUs. 
If the State imposes control measures under this section on only EGUs, 
the Annual EGU SO2 Budget for the State shall not exceed the 
amount, during the indicated periods, specified in paragraph (e)(2) of 
this section.
    (ii) The Annual Non-EGU SO2 Reduction Requirement, if 
applicable, is defined as the total amount of SO2 emission 
reductions that the State demonstrates, in accordance with paragraph (g) 
of this section, it will achieve from non-EGUs during the appropriate 
period. If the State meets the requirements of paragraph (a) of this 
section by imposing control measures on only non-EGUs, then the State's 
Annual Non-EGU SO2 Reduction Requirement shall equal or 
exceed, during the appropriate periods, the amount determined in 
accordance with paragraph (e)(3) of this section.
    (iii) If a State meets the requirements of paragraph (a) of this 
section by imposing control measures on both EGUs and non-EGUs, then:
    (A) The Annual Non-EGU SO2 Reduction Requirement shall 
equal or exceed the difference between the amount specified in paragraph 
(e)(2) of this section for the appropriate period and the amount of the 
State's Annual EGU SO2 Budget specified in the SIP revision 
for the appropriate period; and
    (B) The Annual EGU SO2 Budget shall not exceed, during 
the indicated periods, the amount specified in paragraph (e)(2) of this 
section plus the amount of the Annual Non-EGU SO2 Reduction 
Requirement under paragraph (e)(1)(iii)(A) of this section for the 
appropriate period.
    (2) For a State that complies with the requirements of paragraph (a) 
of this section by imposing control measures on only EGUs, the amount of 
the Annual EGU SO2 Budget, in tons of SO2 per 
year, shall be as follows, for the indicated State for the indicated 
period:

------------------------------------------------------------------------
                                 Annual EGU SO2        Annual EGU SO2
            State             budget for 2010-2014   budget for 2015 and
                                     (tons)           thereafter (tons)
------------------------------------------------------------------------
Alabama.....................               157,582               110,307
Delaware....................                22,411                15,687
District of Columbia........                   708                   495
Florida.....................               253,450               177,415
Georgia.....................               213,057               149,140
Illinois....................               192,671               134,869
Indiana.....................               254,599               178,219
Iowa........................                64,095                44,866
Kentucky....................               188,773               132,141
Louisiana...................                59,948                41,963
Maryland....................                70,697                49,488
Michigan....................               178,605               125,024

[[Page 220]]

 
Minnesota...................                49,987                34,991
Mississippi.................                33,763                23,634
Missouri....................               137,214                96,050
New Jersey..................                32,392                22,674
New York....................               135,139                94,597
North Carolina..............               137,342                96,139
Ohio........................               333,520               233,464
Pennsylvania................               275,990               193,193
South Carolina..............                57,271                40,089
Tennessee...................               137,216                96,051
Texas.......................               320,946               224,662
Virginia....................                63,478                44,435
West Virginia...............               215,881               151,117
Wisconsin...................                87,264                61,085
------------------------------------------------------------------------

    (3) For a State that complies with the requirements of paragraph (a) 
of this section by imposing control measures on only non-EGUs, the 
amount of the Annual Non-EGU SO2 Reduction Requirement, in 
tons of SO2 per year, shall be determined, for the State for 
2010 and thereafter, by subtracting the amount of the State's Annual EGU 
SO2 Budget for the appropriate year, specified in paragraph 
(e)(2) of this section, from an amount equal to 2 times the State's 
Annual EGU SO2 Budget for 2010 through 2014, specified in 
paragraph (e)(2) of this section.
    (f) Each SIP revision must set forth control measures to meet the 
amounts specified in paragraph (e) of this section, as applicable, 
including the following:
    (1) A description of enforcement methods including, but not limited 
to:
    (i) Procedures for monitoring compliance with each of the selected 
control measures;
    (ii) Procedures for handling violations; and
    (iii) A designation of agency responsibility for enforcement of 
implementation.
    (2)(i) If a State elects to impose control measures on EGUs, then 
those measures must impose an annual SO2 mass emissions cap 
on all such sources in the State.
    (ii) If a State elects to impose control measures on fossil fuel-
fired non-EGUs that are boilers or combustion turbines with a maximum 
design heat input greater than 250 mmBtu/hr, then those measures must 
impose an annual SO2 mass emissions cap on all such sources 
in the State.
    (iii) If a State elects to impose control measures on non-EGUs other 
than those described in paragraph (f)(2)(ii) of this section, then those 
measures must impose an annual SO2 mass emissions cap on all 
such sources in the State, or the State must demonstrate why such 
emissions cap is not practicable, and adopt alternative requirements 
that ensure that the State will comply with its requirements under 
paragraph (e) of this section, as applicable, in 2010 and subsequent 
years.
    (g)(1) Each SIP revision that contains control measures covering 
non-EGUs as part or all of a State's obligation in meeting its 
requirement under paragraph (a) of this section must demonstrate that 
such control measures are adequate to provide for the timely compliance 
with the State's Annual Non-EGU SO2 Reduction Requirement 
under paragraph (e) of this section and are not adopted or implemented 
by the State, as of May 12, 2005, and are not adopted or implemented by 
the federal government, as of the date of submission of the SIP revision 
by the State to EPA.
    (2) The demonstration under paragraph (g)(1) of this section must 
include the following, with respect to each source category of non-EGUs 
for which the SIP revision requires control measures:
    (i) A detailed historical baseline inventory of SO2 mass 
emissions from the source category in a representative year consisting, 
at the State's election, of 2002, 2003, 2004, or 2005, or an average of 
2 or more of those years, absent the control measures specified in the 
SIP revision.

[[Page 221]]

    (A) This inventory must represent estimates of actual emissions 
based on monitoring data in accordance with part 75 of this chapter, if 
the source category is subject to part 75 monitoring requirements in 
accordance with part 75 of this chapter.
    (B) In the absence of monitoring data in accordance with part 75 of 
this chapter, actual emissions must be quantified, to the maximum extent 
practicable, with the same degree of assurance with which emissions are 
quantified for sources subject to part 75 of this chapter and using 
source-specific or source-category-specific assumptions that ensure a 
source's or source category's actual emissions are not overestimated. If 
a State uses factors to estimate emissions, production or utilization, 
or effectiveness of controls or rules for a source category, such 
factors must be chosen to ensure that emissions are not overestimated.
    (C) For measures to reduce emissions from motor vehicles, emission 
estimates must be based on an emissions model that has been approved by 
EPA for use in SIP development and must be consistent with the planning 
assumptions regarding vehicle miles traveled and other factors current 
at the time of the SIP development.
    (D) For measures to reduce emissions from nonroad engines or 
vehicles, emission estimates methodologies must be approved by EPA.
    (ii) A detailed baseline inventory of SO2 mass emissions 
from the source category in the years 2010 and 2015, absent the control 
measures specified in the SIP revision and reflecting changes in these 
emissions from the historical baseline year to the years 2010 and 2015, 
based on projected changes in the production input or output, 
population, vehicle miles traveled, economic activity, or other factors 
as applicable to this source category.
    (A) These inventories must account for implementation of any control 
measures that are adopted or implemented by the State, as of May 12, 
2005, or adopted or implemented by the federal government, as of the 
date of submission of the SIP revision by the State to EPA, and must 
exclude any control measures specified in the SIP revision to meet the 
SO2 emissions reduction requirements of this section.
    (B) Economic and population forecasts must be as specific as 
possible to the applicable industry, State, and county of the source or 
source category and must be consistent with both national projections 
and relevant official planning assumptions, including estimates of 
population and vehicle miles traveled developed through consultation 
between State and local transportation and air quality agencies. 
However, if these official planning assumptions are inconsistent with 
official U.S. Census projections of population or with energy 
consumption projections contained in the U.S. Department of Energy's 
most recent Annual Energy Outlook, then the SIP revision must make 
adjustments to correct the inconsistency or must demonstrate how the 
official planning assumptions are more accurate.
    (C) These inventories must account for any changes in production 
method, materials, fuels, or efficiency that are expected to occur 
between the historical baseline year and 2010 or 2015, as appropriate.
    (iii) A projection of SO2 mass emissions in 2010 and 2015 
from the source category assuming the same projected changes as under 
paragraph (g)(2)(ii) of this section and resulting from implementation 
of each of the control measures specified in the SIP revision.
    (A) These inventories must address the possibility that the State's 
new control measures may cause production or utilization, and emissions, 
to shift to unregulated or less stringently regulated sources in the 
source category in the same or another State, and these inventories must 
include any such amounts of emissions that may shift to such other 
sources.
    (B) The State must provide EPA with a summary of the computations, 
assumptions, and judgments used to determine the degree of reduction in 
projected 2010 and 2015 SO2 emissions that will be achieved 
from the implementation of the new control measures compared to the 
relevant baseline emissions inventory.
    (iv) The result of subtracting the amounts in paragraph (g)(2)(iii) 
of this section for 2010 and 2015, respectively,

[[Page 222]]

from the lower of the amounts in paragraph (g)(2)(i) or (g)(2)(ii) of 
this section for 2010 and 2015, respectively, may be credited towards 
the State's Annual Non-EGU SO2 Reduction Requirement in 
paragraph (e)(3) of this section for the appropriate period.
    (v) Each SIP revision must identify the sources of the data used in 
each estimate and each projection of emissions.
    (h) Each SIP revision must comply with Sec. 51.116 (regarding data 
availability).
    (i) Each SIP revision must provide for monitoring the status of 
compliance with any control measures adopted to meet the State's 
requirements under paragraph (e) of this section, as follows:
    (1) The SIP revision must provide for legally enforceable procedures 
for requiring owners or operators of stationary sources to maintain 
records of, and periodically report to the State:
    (i) Information on the amount of SO2 emissions from the 
stationary sources; and
    (ii) Other information as may be necessary to enable the State to 
determine whether the sources are in compliance with applicable portions 
of the control measures;
    (2) The SIP revision must comply with Sec. 51.212 (regarding 
testing, inspection, enforcement, and complaints);
    (3) If the SIP revision contains any transportation control 
measures, then the SIP revision must comply with Sec. 51.213 (regarding 
transportation control measures);
    (4)(i) If the SIP revision contains measures to control EGUs, then 
the SIP revision must require such sources to comply with the 
monitoring, recordkeeping, and reporting provisions of part 75 of this 
chapter.
    (ii) If the SIP revision contains measures to control fossil fuel-
fired non-EGUs that are boilers or combustion turbines with a maximum 
design heat input greater than 250 mmBtu/hr, then the SIP revision must 
require such sources to comply with the monitoring, recordkeeping, and 
reporting provisions of part 75 of this chapter.
    (iii) If the SIP revision contains measures to control any other 
non-EGUs that are not described in paragraph (i)(4)(ii) of this section, 
then the SIP revision must require such sources to comply with the 
monitoring, recordkeeping, and reporting provisions of part 75 of this 
chapter, or the State must demonstrate why such requirements are not 
practicable and adopt alternative requirements that ensure that the 
required emissions reductions will be quantified, to the maximum extent 
practicable, with the same degree of assurance with which emissions are 
quantified for sources subject to part 75 of this chapter.
    (j) Each SIP revision must show that the State has legal authority 
to carry out the SIP revision, including authority to:
    (1) Adopt emissions standards and limitations and any other measures 
necessary for attainment and maintenance of the State's relevant Annual 
EGU SO2 Budget or the Annual Non-EGU SO2 Reduction 
Requirement, as applicable, under paragraph (e) of this section;
    (2) Enforce applicable laws, regulations, and standards and seek 
injunctive relief;
    (3) Obtain information necessary to determine whether air pollution 
sources are in compliance with applicable laws, regulations, and 
standards, including authority to require recordkeeping and to make 
inspections and conduct tests of air pollution sources; and
    (4)(i) Require owners or operators of stationary sources to install, 
maintain, and use emissions monitoring devices and to make periodic 
reports to the State on the nature and amounts of emissions from such 
stationary sources; and
    (ii) Make the data described in paragraph (j)(4)(i) of this section 
available to the public within a reasonable time after being reported 
and as correlated with any applicable emissions standards or 
limitations.
    (k)(1) The provisions of law or regulation that the State determines 
provide the authorities required under this section must be specifically 
identified, and copies of such laws or regulations must be submitted 
with the SIP revision.
    (2) Legal authority adequate to fulfill the requirements of 
paragraphs (j)(3)

[[Page 223]]

and (4) of this section may be delegated to the State under section 114 
of the CAA.
    (l)(1) A SIP revision may assign legal authority to local agencies 
in accordance with Sec. 51.232.
    (2) Each SIP revision must comply with Sec. 51.240 (regarding 
general plan requirements).
    (m) Each SIP revision must comply with Sec. 51.280 (regarding 
resources).
    (n) Each SIP revision must provide for State compliance with the 
reporting requirements in Sec. 51.125.
    (o)(1) Notwithstanding any other provision of this section, if a 
State adopts regulations substantively identical to subparts AAA through 
III of part 96 of this chapter (CAIR SO2 Trading Program), 
incorporates such subparts by reference into its regulations, or adopts 
regulations that differ substantively from such subparts only as set 
forth in paragraph (o)(2) of this section, then such emissions trading 
program in the State's SIP revision is automatically approved as meeting 
the requirements of paragraph (e) of this section, provided that the 
State has the legal authority to take such action and to implement its 
responsibilities under such regulations. Before January 1, 2009, a 
State's regulations shall be considered to be substantively identical to 
subparts AAA through III of part 96 of the chapter, or differing 
substantively only as set forth in paragraph (o)(2) of this section, 
regardless of whether the State's regulations include the definition of 
``Biomass'', paragraph (3) of the definition of ``Cogeneration unit'', 
and the second sentence of the definition of ``Total energy input'' in 
Sec. 96.202 of this chapter promulgated on October 19, 2007, provided 
that the State timely submits to the Administrator a SIP revision that 
revises the State's regulations to include such provisions. Submission 
to the Administrator of a SIP revision that revises the State's 
regulations to include such provisions shall be considered timely if the 
submission is made by January 1, 2009.
    (2) If a State adopts an emissions trading program that differs 
substantively from subparts AAA through III of part 96 of this chapter 
only as follows, then the emissions trading program is approved as set 
forth in paragraph (o)(1) of this section.
    (i) The State may decline to adopt the CAIR SO2 opt-in 
provisions of subpart III of this part and the provisions applicable 
only to CAIR SO2 opt-in units in subparts AAA through HHH of 
this part.
    (ii) The State may decline to adopt the CAIR SO2 opt-in 
provisions of Sec. 96.288(b) of this chapter and the provisions of 
subpart III of this part applicable only to CAIR SO2 opt-in 
units under Sec. 96.288(b).
    (iii) The State may decline to adopt the CAIR SO2 opt-in 
provisions of Sec. 96.288(c) of this chapter and the provisions of 
subpart II of this part applicable only to CAIR SO2 opt-in 
units under Sec. 96.288(c).
    (3) A State that adopts an emissions trading program in accordance 
with paragraph (o)(1) or (2) of this section is not required to adopt an 
emissions trading program in accordance with Sec. 96.123 (o)(1) or (2) 
or (aa)(1) or (2) of this chapter.
    (4) If a State adopts an emissions trading program that differs 
substantively from subparts AAA through III of part 96 of this chapter, 
other than as set forth in paragraph (o)(2) of this section, then such 
emissions trading program is not automatically approved as set forth in 
paragraph (o)(1) or (2) of this section and will be reviewed by the 
Administrator for approvability in accordance with the other provisions 
of this section, provided that the SO2 allowances issued 
under such emissions trading program shall not, and the SIP revision 
shall state that such SO2 allowances shall not, qualify as 
CAIR SO2 allowances under any emissions trading program 
approved under paragraph (o)(1) or (2) of this section.
    (p) If a State's SIP revision does not contain an emissions trading 
program approved under paragraph (o)(1) or (2) of this section but 
contains control measures on EGUs as part or all of a State's obligation 
in meeting its requirement under paragraph (a) of this section:
    (1) The SIP revision shall provide, for each year that the State has 
such obligation, for the permanent retirement of an amount of Acid Rain 
allowances allocated to sources in the State for

[[Page 224]]

that year and not deducted by the Administrator under the Acid Rain 
Program and any emissions trading program approved under paragraph 
(o)(1) or (2) of this section, equal to the difference between--
    (A) The total amount of Acid Rain allowances allocated under the 
Acid Rain Program to the sources in the State for that year; and
    (B) If the State's SIP revision contains only control measures on 
EGUs, the State's Annual EGU SO2 Budget for the appropriate 
period as specified in paragraph (e)(2) of this section or, if the 
State's SIP revision contains control measures on EGUs and non-EGUs, the 
State's Annual EGU SO2 Budget for the appropriate period as 
specified in the SIP revision.
    (2) The SIP revision providing for permanent retirement of Acid Rain 
allowances under paragraph (p)(1) of this section must ensure that such 
allowances are not available for deduction by the Administrator under 
the Acid Rain Program and any emissions trading program approved under 
paragraph (o)(1) or (2) of this section.
    (q) The terms used in this section shall have the following 
meanings:
    Acid Rain allowance means a limited authorization issued by the 
Administrator under the Acid Rain Program to emit up to one ton of 
sulfur dioxide during the specified year or any year thereafter, except 
as otherwise provided by the Administrator.
    Acid Rain Program means a multi-State sulfur dioxide and nitrogen 
oxides air pollution control and emissions reduction program established 
by the Administrator under title IV of the CAA and parts 72 through 78 
of this chapter.
    Administrator means the Administrator of the United States 
Environmental Protection Agency or the Administrator's duly authorized 
representative.
    Allocate or allocation means, with regard to allowances, the 
determination of the amount of allowances to be initially credited to a 
source or other entity.
    Biomass means--
    (1) Any organic material grown for the purpose of being converted to 
energy;
    (2) Any organic byproduct of agriculture that can be converted into 
energy; or
    (3) Any material that can be converted into energy and is 
nonmerchantable for other purposes, that is segregated from other 
nonmerchantable material, and that is;
    (i) A forest-related organic resource, including mill residues, 
precommercial thinnings, slash, brush, or byproduct from conversion of 
trees to merchantable material; or
    (ii) A wood material, including pallets, crates, dunnage, 
manufacturing and construction materials (other than pressure-treated, 
chemically-treated, or painted wood products), and landscape or right-
of-way tree trimmings.
    Boiler means an enclosed fossil- or other-fuel-fired combustion 
device used to produce heat and to transfer heat to recirculating water, 
steam, or other medium.
    Bottoming-cycle cogeneration unit means a cogeneration unit in which 
the energy input to the unit is first used to produce useful thermal 
energy and at least some of the reject heat from the useful thermal 
energy application or process is then used for electricity production.
    Clean Air Act or CAA means the Clean Air Act, 42 U.S.C. 7401, et 
seq.
    Cogeneration unit means a stationary, fossil-fuel-fired boiler or 
stationary, fossil-fuel-fired combustion turbine:
    (1) Having equipment used to produce electricity and useful thermal 
energy for industrial, commercial, heating, or cooling purposes through 
the sequential use of energy; and
    (2) Producing during the 12-month period starting on the date the 
unit first produces electricity and during any calendar year after the 
calendar year in which the unit first produces electricity--
    (i) For a topping-cycle cogeneration unit,
    (A) Useful thermal energy not less than 5 percent of total energy 
output; and
    (B) Useful power that, when added to one-half of useful thermal 
energy produced, is not less then 42.5 percent of total energy input, if 
useful thermal energy produced is 15 percent or more of total energy 
output, or not less than

[[Page 225]]

45 percent of total energy input, if useful thermal energy produced is 
less than 15 percent of total energy output.
    (ii) For a bottoming-cycle cogeneration unit, useful power not less 
than 45 percent of total energy input;
    (3) Provided that the total energy input under paragraphs (2)(i)(B) 
and (2)(ii) of this definition shall equal the unit's total energy input 
from all fuel except biomass if the unit is a boiler.
    Combustion turbine means:
    (1) An enclosed device comprising a compressor, a combustor, and a 
turbine and in which the flue gas resulting from the combustion of fuel 
in the combustor passes through the turbine, rotating the turbine; and
    (2) If the enclosed device under paragraph (1) of this definition is 
combined cycle, any associated duct burner, heat recovery steam 
generator, and steam turbine.
    Commence operation means to have begun any mechanical, chemical, or 
electronic process, including, with regard to a unit, start-up of a 
unit's combustion chamber.
    Electric generating unit or EGU means:
    (1)(i) Except as provided in paragraph (2) of this definition, a 
stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired 
combustion turbine serving at any time, since the later of November 15, 
1990 or the start-up of the unit's combustion chamber, a generator with 
nameplate capacity of more than 25 MWe producing electricity for sale.
    (ii) If a stationary boiler or stationary combustion turbine that, 
under paragraph (1)(i) of this section, is not an electric generating 
unit begins to combust fossil fuel or to serve a generator with 
nameplate capacity of more than 25 MWe producing electricity for sale, 
the unit shall become an electric generating unit as provided in 
paragraph (1)(i) of this section on the first date on which it both 
combusts fossil fuel and serves such generator.
    (2) A unit that meets the requirements set forth in paragraphs 
(2)(i)(A), (2)(ii)(A), or (2)(ii)(B) of this definition paragraph shall 
not be an electric generating unit:
    (i)(A) Any unit that is an electric generating unit under paragraph 
(1)(i) or (ii) of this definition:
    (1) Qualifying as a cogeneration unit during the 12-month period 
starting on the date the unit first produces electricity and continuing 
to qualify as a cogeneration unit; and
    (2) Not serving at any time, since the later of November 15, 1990 or 
the start-up of the unit's combustion chamber, a generator with 
nameplate capacity of more than 25 MWe supplying in any calendar year 
more than one-third of the unit's potential electric output capacity or 
219,000 MWh, whichever is greater, to any utility power distribution 
system for sale.
    (B) If a unit qualifies as a cogeneration unit during the 12-month 
period starting on the date the unit first produces electricity and 
meets the requirements of paragraphs (2)(i)(A) of this section for at 
least one calendar year, but subsequently no longer meets all such 
requirements, the unit shall become an electric generating unit starting 
on the earlier of January 1 after the first calendar year during which 
the unit first no longer qualifies as a cogeneration unit or January 1 
after the first calendar year during which the unit no longer meets the 
requirements of paragraph (2)(i)(A)(2) of this section.
    (ii)(A) Any unit that is an electric generating unit under paragraph 
(1)(i) or (ii) of this definition commencing operation before January 1, 
1985:
    (1) Qualifying as a solid waste incineration unit; and
    (2) With an average annual fuel consumption of non-fossil fuel for 
1985-1987 exceeding 80 percent (on a Btu basis) and an average annual 
fuel consumption of non-fossil fuel for any 3 consecutive calendar years 
after 1990 exceeding 80 percent (on a Btu basis).
    (B) Any unit that is an electric generating unit under paragraph 
(1)(i) or (ii) of this definition commencing operation on or after 
January 1, 1985:
    (1) Qualifying as a solid waste incineration unit; and
    (2) With an average annual fuel consumption of non-fossil fuel for 
the first 3 calendar years of operation exceeding 80 percent (on a Btu 
basis) and an average annual fuel consumption of non-fossil fuel for any 
3 consecutive calendar years after 1990 exceeding 80 percent (on a Btu 
basis).

[[Page 226]]

    (C) If a unit qualifies as a solid waste incineration unit and meets 
the requirements of paragraph (2)(ii)(A) or (B) of this section for at 
least 3 consecutive calendar years, but subsequently no longer meets all 
such requirements, the unit shall become an electric generating unit 
starting on the earlier of January 1 after the first calendar year 
during which the unit first no longer qualifies as a solid waste 
incineration unit or January 1 after the first 3 consecutive calendar 
years after 1990 for which the unit has an average annual fuel 
consumption of fossil fuel of 20 percent or more.
    Fossil fuel means natural gas, petroleum, coal, or any form of 
solid, liquid, or gaseous fuel derived from such material.
    Fossil-fuel-fired means, with regard to a unit, combusting any 
amount of fossil fuel in any calendar year.
    Generator means a device that produces electricity.
    Maximum design heat input means the maximum amount of fuel per hour 
(in Btu/hr) that a unit is capable of combusting on a steady state basis 
as of the initial installation of the unit as specified by the 
manufacturer of the unit.
    NAAQS means National Ambient Air Quality Standard.
    Nameplate capacity means, starting from the initial installation of 
a generator, the maximum electrical generating output (in MWe) that the 
generator is capable of producing on a steady state basis and during 
continuous operation (when not restricted by seasonal or other deratings 
as of such installation as specified by the manufacturer of the 
generator or, starting from the completion of any subsequent physical 
change in the generator resulting in an increase in the maximum 
electrical generating output (in MWe) that the generator is capable of 
producing on a steady state basis and during continuous operation (when 
not restricted by seasonal or other deratings), such increased maximum 
amount as of such completion as specified by the person conducting the 
physical change.
    Non-EGU means a source of SO2 emissions that is not an 
EGU.
    Potential electrical output capacity means 33 percent of a unit's 
maximum design heat input, divided by 3,413 Btu/kWh, divided by 1,000 
kWh/MWh, and multiplied by 8,760 hr/yr.
    Sequential use of energy means:
    (1) For a topping-cycle cogeneration unit, the use of reject heat 
from electricity production in a useful thermal energy application or 
process; or
    (2) For a bottoming-cycle cogeneration unit, the use of reject heat 
from useful thermal energy application or process in electricity 
production.
    Solid waste incineration unit means a stationary, fossil-fuel-fired 
boiler or stationary, fossil-fuel-fired combustion turbine that is a 
``solid waste incineration unit'' as defined in section 129(g)(1) of the 
Clean Air Act.
    Topping-cycle cogeneration unit means a cogeneration unit in which 
the energy input to the unit is first used to produce useful power, 
including electricity, and at least some of the reject heat from the 
electricity production is then used to provide useful thermal energy.
    Total energy input means, with regard to a cogeneration unit, total 
energy of all forms supplied to the cogeneration unit, excluding energy 
produced by the cogeneration unit itself.
    Total energy output means, with regard to a cogeneration unit, the 
sum of useful power and useful thermal energy produced by the 
cogeneration unit. Each form of energy supplied shall be measured by the 
lower heating value of that form of energy calculated as follows:

LHV = HHV - 10.55(W + 9H)

Where:

LHV = lower heating value of fuel in Btu/lb,
HHV = higher heating value of fuel in Btu/lb,
W = Weight % of moisture in fuel, and
H = Weight % of hydrogen in fuel.

    Unit means a stationary, fossil-fuel-fired boiler or a stationary, 
fossil-fuel fired combustion turbine.
    Useful power means, with regard to a cogeneration unit, electricity 
or mechanical energy made available for use, excluding any such energy 
used in the power production process (which process includes, but is not 
limited to, any on-site processing or treatment of fuel

[[Page 227]]

combusted at the unit and any on-site emission controls).
    Useful thermal energy means, with regard to a cogeneration unit, 
thermal energy that is:
    (1) Made available to an industrial or commercial process, excluding 
any heat contained in condensate return or makeup water;
    (2) Used in a heating application (e.g., space heating or domestic 
hot water heating); or
    (3) Used in a space cooling application (i.e., thermal energy used 
by an absorption chiller).
    Utility power distribution system means the portion of an 
electricity grid owned or operated by a utility and dedicated to 
delivering electricity to customers.
    (r) Notwithstanding any other provision of this section, a State may 
adopt, and include in a SIP revision submitted by March 31, 2007, 
regulations relating to the Federal CAIR SO2 Trading Program 
under subparts AAA through HHH of part 97 of this chapter as follows. 
The State may adopt the following CAIR opt-in unit provisions:
    (1) Provisions for CAIR opt-in units, including provisions for 
applications for CAIR opt-in permits, approval of CAIR opt-in permits, 
treatment of units as CAIR opt-in units, and allocation and recordation 
of CAIR SO2 allowances for CAIR opt-in units, that are 
substantively identical to subpart III of part 96 of this chapter and 
the provisions of subparts AAA through HHH that are applicable to CAIR 
opt-in units or units for which a CAIR opt-in permit application is 
submitted and not withdrawn and a CAIR opt-in permit is not yet issued 
or denied;
    (2) Provisions for CAIR opt-in units, including provisions for 
applications for CAIR opt-in permits, approval of CAIR opt-in permits, 
treatment of units as CAIR opt-in units, and allocation and recordation 
of CAIR SO2 allowances for CAIR opt-in units, that are 
substantively identical to subpart III of part 96 of this chapter and 
the provisions of subparts AAA through HHH that are applicable to CAIR 
opt-in units or units for which a CAIR opt-in permit application is 
submitted and not withdrawn and a CAIR opt-in permit is not yet issued 
or denied, except that the provisions exclude Sec. 96.288(b) of this 
chapter and the provisions of subpart III of part 96 of this chapter 
that apply only to units covered by Sec. 96.288(b) of this chapter; or
    (3) Provisions for applications for CAIR opt-in units, including 
provisions for CAIR opt-in permits, approval of CAIR opt-in permits, 
treatment of units as CAIR opt-in units, and allocation and recordation 
of CAIR SO2 allowances for CAIR opt-in units, that are 
substantively identical to subpart III of part 96 of this chapter and 
the provisions of subparts AAA through HHH that are applicable to CAIR 
opt-in units or units for which a CAIR opt-in permit application is 
submitted and not withdrawn and a CAIR opt-in permit is not yet issued 
or denied, except that the provisions exclude Sec. 96.288(c) of this 
chapter and the provisions of subpart III of part 96 of this chapter 
that apply only to units covered by Sec. 96.288(c) of this chapter.
    (s) Notwithstanding any provisions of paragraphs (a) through (r) of 
this section, subparts AAA through III of part 96 of this chapter, 
subparts AAA through III of part 97 of this chapter, and any State's SIP 
to the contrary:
    (1) With regard to any control period that begins after December 31, 
2014, the Administrator:
    (i) Rescinds the determination in paragraph (a) of this section that 
the States identified in paragraph (c) of this section must submit a SIP 
revision with respect to the fine particles (PM2.5) NAAQS 
meeting the requirements of paragraphs (b) through (r) of this section; 
and
    (ii) Will not carry out any of the functions set forth for the 
Administrator in subparts AAA through III of part 96 of this chapter, 
subparts AAA through III of part 97 of this chapter, or in any emissions 
trading program in a State's SIP approved under this section; and
    (2) The Administrator will not deduct for excess emissions any CAIR 
SO2 allowances allocated for 2015 or any year thereafter.

[70 FR 25328, May 12, 2005, as amended at 71 FR 25302, 25372, Apr. 28, 
2006; 71 FR 74793, Dec. 13, 2006; 72 FR 59204, Oct. 19, 2007; 74 FR 
56726, Nov. 3, 2009; 76 FR 48353, Aug. 8, 2011; 79 FR 71671, Dec. 3, 
2014]

[[Page 228]]



Sec. 51.125  [Reserved]



Sec. 51.126  Determination of widespread use of ORVR and waiver of
CAA section 182(b)(3) Stage II gasoline vapor recovery requirements.

    (a) Pursuant to section 202(a)(6) of the Clean Air Act, the 
Administrator has determined that, effective May 16, 2012, onboard 
refueling vapor recovery (ORVR) systems are in widespread use in the 
motor vehicle fleet within the United States.
    (b) Effective May 16, 2012, the Administrator waives the requirement 
of Clean Air Act section 182(b)(3) for Stage II vapor recovery systems 
in ozone nonattainment areas regardless of classification. States must 
submit and receive EPA approval of a revision to their approved State 
Implementation Plans before removing Stage II requirements that are 
contained therein.

[77 FR 28782, May 16, 2012]



        Subpart H_Prevention of Air Pollution Emergency Episodes

    Source: 51 FR 40668, Nov. 7, 1986, unless otherwise noted.



Sec. 51.150  Classification of regions for episode plans.

    (a) This section continues the classification system for episode 
plans. Each region is classified separately with respect to each of the 
following pollutants: Sulfur oxides, particulate matter, carbon 
monoxide, nitrogen dioxide, and ozone.
    (b) Priority I Regions means any area with greater ambient 
concentrations than the following:
    (1) Sulfur dioxide--100 [micro]g/m\3\ (0.04 ppm) annual arithmetic 
mean; 455 [micro]g/m\3\ (0.17 ppm) 24-hour maximum.
    (2) Particulate matter--95 [micro]g/m\3\ annual geometric mean; 325 
[micro]g/m\3\ 24-hour maximum.
    (3) Carbon monoxide--55 mg/m\3\ (48 ppm) 1-hour maximum; 14 mg/m\3\ 
(12 ppm) 8-hour maximum.
    (4) Nitrogen dioxide--100 [micro]g/m\3\ (0.06 ppm) annual arithmetic 
mean.
    (5) Ozone--195 [micro]g/m\3\ (0.10 ppm) 1-hour maximum.
    (c) Priority IA Region means any area which is Priority I primarily 
because of emissions from a single point source.
    (d) Priority II Region means any area which is not a Priority I 
region and has ambient concentrations between the following:
    (1) Sulfur Dioxides--60-100 [micro]g/m\3\ (0.02-0.04 ppm) annual 
arithmetic mean; 260-445 [micro]g/m\3\ (0.10-0.17 ppm) 24-hour maximum; 
any concentration above 1,300 [micro]g/m\3\ (0.50 ppm) three-hour 
average.
    (2) Particulate matter--60-95 [micro]g/m\3\ annual geometric mean; 
150-325 [micro]g/m\3\ 24-hour maximum.
    (e) In the absence of adequate monitoring data, appropriate models 
must be used to classify an area under paragraph (b) of this section, 
consistent with the requirements contained in Sec. 51.112(a).
    (f) Areas which do not meet the above criteria are classified 
Priority III.

[51 FR 40668, Nov. 7, 1986, as amended at 58 FR 38822, July 20, 1993]



Sec. 51.151  Significant harm levels.

    Each plan for a Priority I region must include a contingency plan 
which must, as a minimum, provide for taking action necessary to prevent 
ambient pollutant concentrations at any location in such region from 
reaching the following levels:

Sulfur dioxide--2.620 [micro]g/m\3\ (1.0 ppm) 24-hour average.
PM10--600 micrograms/cubic meter; 24-hour average.
Carbon monoxide--57.5 mg/m\3\ (50 ppm) 8-hour average; 86.3 mg/m\3\ (75 
ppm) 4-hour average; 144 mg/m\3\ (125 ppm) 1-hour average.
Ozone--1,200 ug/m\3\ (0.6 ppm) 2-hour average.
Nitrogen dioxide--3.750 ug/m\3\ (2.0 ppm) 1-hour average; 938 ug/m\3\ 
(0.5 ppm) 24-hour average.

[51 FR 40668, Nov. 7, 1986, as amended at 52 FR 24713, July 1, 1987]



Sec. 51.152  Contingency plans.

    (a) Each contingency plan must--
    (1) Specify two or more stages of episode criteria such as those set 
forth in appendix L to this part, or their equivalent;
    (2) Provide for public announcement whenever any episode stage has 
been determined to exist; and

[[Page 229]]

    (3) Specify adequate emission control actions to be taken at each 
episode stage. (Examples of emission control actions are set forth in 
appendix L.)
    (b) Each contingency plan for a Priority I region must provide for 
the following:
    (1) Prompt acquisition of forecasts of atmospheric stagnation 
conditions and of updates of such forecasts as frequently as they are 
issued by the National Weather Service.
    (2) Inspection of sources to ascertain compliance with applicable 
emission control action requirements.
    (3) Communications procedures for transmitting status reports and 
orders as to emission control actions to be taken during an episode 
stage, including procedures for contact with public officials, major 
emission sources, public health, safety, and emergency agencies and news 
media.
    (c) Each plan for a Priority IA and II region must include a 
contingency plan that meets, as a minimum, the requirements of 
paragraphs (b)(1) and (b)(2) of this section. Areas classified Priority 
III do not need to develop episode plans.
    (d) Notwithstanding the requirements of paragraphs (b) and (c) of 
this section, the Administrator may, at his discretion--
    (1) Exempt from the requirements of this section those portions of 
Priority I, IA, or II regions which have been designated as attainment 
or unclassifiable for national primary and secondary standards under 
section 107 of the Act; or
    (2) Limit the requirements pertaining to emission control actions in 
Priority I regions to--
    (i) Urbanized areas as identified in the most recent United States 
Census, and
    (ii) Major emitting facilities, as defined by section 169(1) of the 
Act, outside the urbanized areas.



Sec. 51.153  Reevaluation of episode plans.

    (a) States should periodically reevaluate priority classifications 
of all Regions or portion of Regions within their borders. The 
reevaluation must consider the three most recent years of air quality 
data. If the evaluation indicates a change to a higher priority 
classification, appropriate changes in the episode plan must be made as 
expeditiously as practicable.
    (b) [Reserved]



            Subpart I_Review of New Sources and Modifications

    Source: 51 FR 40669, Nov. 7, 1986, unless otherwise noted.



Sec. 51.160  Legally enforceable procedures.

    (a) Each plan must set forth legally enforceable procedures that 
enable the State or local agency to determine whether the construction 
or modification of a facility, building, structure or installation, or 
combination of these will result in--
    (1) A violation of applicable portions of the control strategy; or
    (2) Interference with attainment or maintenance of a national 
standard in the State in which the proposed source (or modification) is 
located or in a neighboring State.
    (b) Such procedures must include means by which the State or local 
agency responsible for final decisionmaking on an application for 
approval to construct or modify will prevent such construction or 
modification if--
    (1) It will result in a violation of applicable portions of the 
control strategy; or
    (2) It will interfere with the attainment or maintenance of a 
national standard.
    (c) The procedures must provide for the submission, by the owner or 
operator of the building, facility, structure, or installation to be 
constructed or modified, of such information on--
    (1) The nature and amounts of emissions to be emitted by it or 
emitted by associated mobile sources;
    (2) The location, design, construction, and operation of such 
facility, building, structure, or installation as may be necessary to 
permit the State or local agency to make the determination referred to 
in paragraph (a) of this section.

[[Page 230]]

    (d) The procedures must provide that approval of any construction or 
modification must not affect the responsibility to the owner or operator 
to comply with applicable portions of the control strategy.
    (e) The procedures must identify types and sizes of facilities, 
buildings, structures, or installations which will be subject to review 
under this section. The plan must discuss the basis for determining 
which facilities will be subject to review.
    (f) The procedures must discuss the air quality data and the 
dispersion or other air quality modeling used to meet the requirements 
of this subpart.
    (1) All applications of air quality modeling involved in this 
subpart shall be based on the applicable models, data bases, and other 
requirements specified in appendix W of this part (Guideline on Air 
Quality Models).
    (2) Where an air quality model specified in appendix W of this part 
(Guideline on Air Quality Models) is inappropriate, the model may be 
modified or another model substituted. Such a modification or 
substitution of a model may be made on a case-by-case basis or, where 
appropriate, on a generic basis for a specific State program. Written 
approval of the Administrator must be obtained for any modification or 
substitution. In addition, use of a modified or substituted model must 
be subject to notice and opportunity for public comment under procedures 
set forth in Sec. 51.102.

[51 FR 40669, Nov. 7, 1986, as amended at 58 FR 38822, July 20, 1993; 60 
FR 40468, Aug. 9, 1995; 61 FR 41840, Aug. 12, 1996]



Sec. 51.161  Public availability of information.

    (a) The legally enforceable procedures in Sec. 51.160 must also 
require the State or local agency to provide opportunity for public 
comment on information submitted by owners and operators. The public 
information must include the agency's analysis of the effect of 
construction or modification on ambient air quality, including the 
agency's proposed approval or disapproval.
    (b) For purposes of paragraph (a) of this section, opportunity for 
public comment shall include, as a minimum--
    (1) Availability for public inspection in at least one location in 
the area affected of the information submitted by the owner or operator 
and of the State or local agency's analysis of the effect on air 
quality. This requirement may be met by making these materials available 
at a physical location or on a public Web site identified by the State 
or local agency;
    (2) A 30-day period for submittal of public comment; and
    (3) A notice by prominent advertisement in the area affected of the 
location of the source information and analysis specified in paragraph 
(b)(1) of this section.
    (c) Where the 30-day comment period required in paragraph (b) of 
this section would conflict with existing requirements for acting on 
requests for permission to construct or modify, the State may submit for 
approval a comment period which is consistent with such existing 
requirements.
    (d) A copy of the notice required by paragraph (b) of this section 
must also be sent to the Administrator through the appropriate Regional 
Office, and to all other State and local air pollution control agencies 
having jurisdiction in the region in which such new or modified 
installation will be located. The notice also must be sent to any other 
agency in the region having responsibility for implementing the 
procedures required under this subpart. For lead, a copy of the notice 
is required for all point sources. The definition of point for lead is 
given in Sec. 51.100(k)(2).

[51 FR 40669, Nov. 7, 1986, as amended at 81 FR 71629, Oct. 18, 2016]



Sec. 51.162  Identification of responsible agency.

    Each plan must identify the State or local agency which will be 
responsible for meeting the requirements of this subpart in each area of 
the State. Where such responsibility rests with an agency other than an 
air pollution control agency, such agency will consult with the 
appropriate State or local air pollution control agency in carrying out 
the provisions of this subpart.

[[Page 231]]



Sec. 51.163  Administrative procedures.

    The plan must include the administrative procedures, which will be 
followed in making the determination specified in paragraph (a) of Sec. 
51.160.



Sec. 51.164  Stack height procedures.

    Such procedures must provide that the degree of emission limitation 
required of any source for control of any air pollutant must not be 
affected by so much of any source's stack height that exceeds good 
engineering practice or by any other dispersion technique, except as 
provided in Sec. 51.118(b). Such procedures must provide that before a 
State issues a permit to a source based on a good engineering practice 
stack height that exceeds the height allowed by Sec. 51.100(ii) (1) or 
(2), the State must notify the public of the availability of the 
demonstration study and must provide opportunity for public hearing on 
it. This section does not require such procedures to restrict in any 
manner the actual stack height of any source.



Sec. 51.165  Permit requirements.

    (a) State Implementation Plan and Tribal Implementation Plan 
provisions satisfying sections 172(c)(5) and 173 of the Act shall meet 
the following conditions:
    (1) All such plans shall use the specific definitions. Deviations 
from the following wording will be approved only if the State 
specifically demonstrates that the submitted definition is more 
stringent, or at least as stringent, in all respects as the 
corresponding definition below:
    (i) Stationary source means any building, structure, facility, or 
installation which emits or may emit a regulated NSR pollutant.
    (ii)(A) Building, structure, facility, or installation means all of 
the pollutant-emitting activities which belong to the same industrial 
grouping, are located on one or more contiguous or adjacent properties, 
and are under the control of the same person (or persons under common 
control) except the activities of any vessel. Pollutant emitting 
activities shall be considered as part of the same industrial grouping 
if they belong to the same Major Group (i.e., which have the same two-
digit code) as described in the Standard Industrial Classification 
Manual, 1972, as amended by the 1977 Supplement (U.S. Government 
Printing Office stock numbers 4101-0065 and 003-005-00176-0, 
respectively).
    (B) The plan may include the following provision: Notwithstanding 
the provisions of paragraph (a)(1)(ii)(A) of this section, building, 
structure, facility, or installation means, for onshore activities under 
Standard Industrial Classification (SIC) Major Group 13: Oil and Gas 
Extraction, all of the pollutant-emitting activities included in Major 
Group 13 that are located on one or more contiguous or adjacent 
properties, and are under the control of the same person (or persons 
under common control). Pollutant emitting activities shall be considered 
adjacent if they are located on the same surface site; or if they are 
located on surface sites that are located within \1/4\ mile of one 
another (measured from the center of the equipment on the surface site) 
and they share equipment. Shared equipment includes, but is not limited 
to, produced fluids storage tanks, phase separators, natural gas 
dehydrators or emissions control devices. Surface site, as used in this 
paragraph (a)(1)(ii)(B), has the same meaning as in 40 CFR 63.761.
    (iii) Potential to emit means the maximum capacity of a stationary 
source to emit a pollutant under its physical and operational design. 
Any physical or operational limitation on the capacity of the source to 
emit a pollutant, including air pollution control equipment and 
restrictions on hours of operation or on the type or amount of material 
combusted, stored, or processed, shall be treated as part of its design 
only if the limitation or the effect it would have on emissions is 
federally enforceable. Secondary emissions do not count in determining 
the potential to emit of a stationary source.
    (iv)(A) Major stationary source means:
    (1) Any stationary source of air pollutants that emits, or has the 
potential to emit, 100 tons per year or more of any regulated NSR 
pollutant (as defined in paragraph (a)(1)(xxxvii) of this section), 
except that lower emissions thresholds shall apply in areas subject to 
subpart 2, subpart 3, or subpart 4 of part D, title I of the Act, 
according to

[[Page 232]]

paragraphs (a)(1)(iv)(A)(1)(i) through (viii) of this section.
    (i) 50 tons per year of Volatile organic compounds in any serious 
ozone nonattainment area.
    (ii) 50 tons per year of Volatile organic compounds in an area 
within an ozone transport region, except for any severe or extreme ozone 
nonattainment area.
    (iii) 25 tons per year of Volatile organic compounds in any severe 
ozone nonattainment area.
    (iv) 10 tons per year of Volatile organic compounds in any extreme 
ozone nonattainment area.
    (v) 50 tons per year of Carbon monoxide in any serious nonattainment 
area for carbon monoxide, where stationary sources contribute 
significantly to Carbon monoxide levels in the area (as determined under 
rules issued by the Administrator).
    (vi) 70 tons per year of PM10 in any serious 
nonattainment area for PM10.
    (vii) 70 tons per year of PM2.5 in any serious 
nonattainment area for PM2.5.
    (viii) 70 tons per year of any individual precursor for 
PM2.5 (as defined in paragraph (a)(1)(xxxvii) of this 
section), in any serious nonattainment area for PM2.5.
    (2) For the purposes of applying the requirements of paragraph 
(a)(8) of this section to stationary sources of nitrogen oxides located 
in an ozone nonattainment area or in an ozone transport region, any 
stationary source which emits, or has the potential to emit, 100 tons 
per year or more of nitrogen oxides emissions, except that the emission 
thresholds in paragraphs (a)(1)(iv)(A)(2)(i) through (vi) of this 
section shall apply in areas subject to subpart 2 of part D, title I of 
the Act.
    (i) 100 tons per year or more of nitrogen oxides in any ozone 
nonattainment area classified as marginal or moderate.
    (ii) 100 tons per year or more of nitrogen oxides in any ozone 
nonattainment area classified as a transitional, submarginal, or 
incomplete or no data area, when such area is located in an ozone 
transport region.
    (iii) 100 tons per year or more of nitrogen oxides in any area 
designated under section 107(d) of the Act as attainment or 
unclassifiable for ozone that is located in an ozone transport region.
    (iv) 50 tons per year or more of nitrogen oxides in any serious 
nonattainment area for ozone.
    (v) 25 tons per year or more of nitrogen oxides in any severe 
nonattainment area for ozone.
    (vi) 10 tons per year or more of nitrogen oxides in any extreme 
nonattainment area for ozone; or
    (3) Any physical change that would occur at a stationary source not 
qualifying under paragraphs (a)(1)(iv)(A)(1) or (2) of this section as a 
major stationary source, if the change would constitute a major 
stationary source by itself.
    (B) A major stationary source that is major for volatile organic 
compounds shall be considered major for ozone
    (C) The fugitive emissions of a stationary source shall not be 
included in determining for any of the purposes of this paragraph 
whether it is a major stationary source, unless the source belongs to 
one of the following categories of stationary sources:
    (1) Coal cleaning plants (with thermal dryers);
    (2) Kraft pulp mills;
    (3) Portland cement plants;
    (4) Primary zinc smelters;
    (5) Iron and steel mills;
    (6) Primary aluminum ore reduction plants;
    (7) Primary copper smelters;
    (8) Municipal incinerators capable of charging more than 250 tons of 
refuse per day;
    (9) Hydrofluoric, sulfuric, or nitric acid plants;
    (10) Petroleum refineries;
    (11) Lime plants;
    (12) Phosphate rock processing plants;
    (13) Coke oven batteries;
    (14) Sulfur recovery plants;
    (15) Carbon black plants (furnace process);
    (16) Primary lead smelters;
    (17) Fuel conversion plants;
    (18) Sintering plants;
    (19) Secondary metal production plants;
    (20) Chemical process plants--The term chemical processing plant 
shall not include ethanol production facilities that produce ethanol by 
natural

[[Page 233]]

fermentation included in NAICS codes 325193 or 312140;
    (21) Fossil-fuel boilers (or combination thereof) totaling more than 
250 million British thermal units per hour heat input;
    (22) Petroleum storage and transfer units with a total storage 
capacity exceeding 300,000 barrels;
    (23) Taconite ore processing plants;
    (24) Glass fiber processing plants;
    (25) Charcoal production plants;
    (26) Fossil fuel-fired steam electric plants of more than 250 
million British thermal units per hour heat input; and
    (27) Any other stationary source category which, as of August 7, 
1980, is being regulated under section 111 or 112 of the Act.
    (v)(A) Major modification means any physical change in or change in 
the method of operation of a major stationary source that would result 
in:
    (1) A significant emissions increase of a regulated NSR pollutant 
(as defined in paragraph (a)(1)(xxxvii) of this section); and
    (2) A significant net emissions increase of that pollutant from the 
major stationary source.
    (B) Any significant emissions increase (as defined in paragraph 
(a)(1)(xxvii) of this section) from any emissions units or net emissions 
increase (as defined in paragraph (a)(1)(vi) of this section) at a major 
stationary source that is significant for volatile organic compounds 
shall be considered significant for ozone.
    (C) A physical change or change in the method of operation shall not 
include:
    (1) Routine maintenance, repair and replacement. Routine 
maintenance, repair and replacement shall include, but not be limited 
to, any activity(s) that meets the requirements of the equipment 
replacement provisions contained in paragraph (h) of this section;

    Note to paragraph (a)(1)(v)(C)(1): On December 24, 2003, the second 
sentence of this paragraph (a)(1)(v)(C)(1) is stayed indefinitely by 
court order. The stayed provisions will become effective immediately if 
the court terminates the stay. At that time, EPA will publish a document 
in the Federal Register advising the public of the termination of the 
stay.

    (2) Use of an alternative fuel or raw material by reason of an order 
under sections 2 (a) and (b) of the Energy Supply and Environmental 
Coordination Act of 1974 (or any superseding legislation) or by reason 
of a natural gas curtailment plan pursuant to the Federal Power Act;
    (3) Use of an alternative fuel by reason of an order or rule section 
125 of the Act;
    (4) Use of an alternative fuel at a steam generating unit to the 
extent that the fuel is generated from municipal solid waste;
    (5) Use of an alternative fuel or raw material by a stationary 
source which;
    (i) The source was capable of accommodating before December 21, 
1976, unless such change would be prohibited under any federally 
enforceable permit condition which was established after December 12, 
1976 pursuant to 40 CFR 52.21 or under regulations approved pursuant to 
40 CFR subpart I or Sec. 51.166, or
    (ii) The source is approved to use under any permit issued under 
regulations approved pursuant to this section;
    (6) An increase in the hours of operation or in the production rate, 
unless such change is prohibited under any federally enforceable permit 
condition which was established after December 21, 1976 pursuant to 40 
CFR 52.21 or regulations approved pursuant to 40 CFR part 51 subpart I 
or 40 CFR 51.166.
    (7) Any change in ownership at a stationary source.
    (8) [Reserved]
    (9) The installation, operation, cessation, or removal of a 
temporary clean coal technology demonstration project, provided that the 
project complies with:
    (i) The State Implementation Plan for the State in which the project 
is located, and
    (ii) Other requirements necessary to attain and maintain the 
national ambient air quality standard during the project and after it is 
terminated.
    (D) This definition shall not apply with respect to a particular 
regulated NSR pollutant when the major stationary source is complying 
with the requirements under paragraph (f) of

[[Page 234]]

this section for a PAL for that pollutant. Instead, the definition at 
paragraph (f)(2)(viii) of this section shall apply.
    (E) For the purpose of applying the requirements of (a)(8) of this 
section to modifications at major stationary sources of nitrogen oxides 
located in ozone nonattainment areas or in ozone transport regions, 
whether or not subject to subpart 2, part D, title I of the Act, any 
significant net emissions increase of nitrogen oxides is considered 
significant for ozone.
    (F) Any physical change in, or change in the method of operation of, 
a major stationary source of volatile organic compounds that results in 
any increase in emissions of volatile organic compounds from any 
discrete operation, emissions unit, or other pollutant emitting activity 
at the source shall be considered a significant net emissions increase 
and a major modification for ozone, if the major stationary source is 
located in an extreme ozone nonattainment area that is subject to 
subpart 2, part D, title I of the Act.
    (G) Fugitive emissions shall not be included in determining for any 
of the purposes of this section whether a physical change in or change 
in the method of operation of a major stationary source is a major 
modification, unless the source belongs to one of the source categories 
listed in paragraph (a)(1)(iv)(C) of this section.
    (vi)(A) Net emissions increase means, with respect to any regulated 
NSR pollutant emitted by a major stationary source, the amount by which 
the sum of the following exceeds zero:
    (1) The increase in emissions from a particular physical change or 
change in the method of operation at a stationary source as calculated 
pursuant to paragraph (a)(2)(ii) of this section; and
    (2) Any other increases and decreases in actual emissions at the 
major stationary source that are contemporaneous with the particular 
change and are otherwise creditable. Baseline actual emissions for 
calculating increases and decreases under this paragraph 
(a)(1)(vi)(A)(2) shall be determined as provided in paragraph 
(a)(1)(xxxv) of this section, except that paragraphs (a)(1)(xxxv)(A)(3) 
and (a)(1)(xxxv)(B)(4) of this section shall not apply.
    (B) An increase or decrease in actual emissions is contemporaneous 
with the increase from the particular change only if it occurs before 
the date that the increase from the particular change occurs;
    (C) An increase or decrease in actual emissions is creditable only 
if:
    (1) It occurs within a reasonable period to be specified by the 
reviewing authority; and
    (2) The reviewing authority has not relied on it in issuing a permit 
for the source under regulations approved pursuant to this section, 
which permit is in effect when the increase in actual emissions from the 
particular change occurs; and
    (3) As it pertains to an increase or decrease in fugitive emissions 
(to the extent quantifiable), it occurs at an emissions unit that is 
part of one of the source categories listed in paragraph (a)(1)(iv)(C) 
of this section or it occurs at an emissions unit that is located at a 
major stationary source that belongs to one of the listed source 
categories. Fugitive emission increases or decreases are not creditable 
for those emissions units located at a facility whose primary activity 
is not represented by one of the source categories listed in paragraph 
(a)(1)(iv)(C) of this section and that are not, by themselves, part of a 
listed source category.
    (D) An increase in actual emissions is creditable only to the extent 
that the new level of actual emissions exceeds the old level.
    (E) A decrease in actual emissions is creditable only to the extent 
that:
    (1) The old level of actual emission or the old level of allowable 
emissions whichever is lower, exceeds the new level of actual emissions;
    (2) It is enforceable as a practical matter at and after the time 
that actual construction on the particular change begins; and
    (3) The reviewing authority has not relied on it in issuing any 
permit under regulations approved pursuant to 40 CFR part 51 subpart I 
or the State has

[[Page 235]]

not relied on it in demonstrating attainment or reasonable further 
progress;
    (4) It has approximately the same qualitative significance for 
public health and welfare as that attributed to the increase from the 
particular change; and
    (F) An increase that results from a physical change at a source 
occurs when the emissions unit on which construction occurred becomes 
operational and begins to emit a particular pollutant. Any replacement 
unit that requires shakedown becomes operational only after a reasonable 
shakedown period, not to exceed 180 days.
    (G) Paragraph (a)(1)(xii)(B) of this section shall not apply for 
determining creditable increases and decreases or after a change.
    (vii) Emissions unit means any part of a stationary source that 
emits or would have the potential to emit any regulated NSR pollutant 
and includes an electric steam generating unit as defined in paragraph 
(a)(1)(xx) of this section. For purposes of this section, there are two 
types of emissions units as described in paragraphs (a)(1)(vii)(A) and 
(B) of this section.
    (A) A new emissions unit is any emissions unit which is (or will be) 
newly constructed and which has existed for less than 2 years from the 
date such emissions unit first operated.
    (B) An existing emissions unit is any emissions unit that does not 
meet the requirements in paragraph (a)(1)(vii)(A) of this section. A 
replacement unit, as defined in paragraph (a)(1)(xxi) of this section, 
is an existing emissions unit.
    (viii) Secondary emissons means emissions which would occur as a 
result of the construction or operation of a major stationary source or 
major modification, but do not come from the major stationary source or 
major modification itself. For the purpose of this section, secondary 
emissions must be specific, well defined, quantifiable, and impact the 
same general area as the stationary source or modification which causes 
the secondary emissions. Secondary emissions include emissions from any 
offsite support facility which would not be constructed or increase its 
emissions except as a result of the construction of operation of the 
major stationary source of major modification. Secondary emissions do 
not include any emissions which come directly from a mobile source such 
as emissions from the tailpipe of a motor vehicle, from a train, or from 
a vessel.
    (ix) Fugitive emissions means those emissions which could not 
reasonably pass through a stack, chimney, vent or other functionally 
equivalent opening.
    (x)(A) Significant means, in reference to a net emissions increase 
or the potential of a source to emit any of the following pollutants, a 
rate of emissions that would equal or exceed any of the following rates:

                         Pollutant Emission Rate

Carbon monoxide: 100 tons per year (tpy)
Nitrogen oxides: 40 tpy
Sulfur dioxide: 40 tpy
Ozone: 40 tpy of Volatile organic compounds or Nitrogen oxides
Lead: 0.6 tpy
PM10: 15 tpy
PM2.5: 10 tpy of direct PM2.5 emissions; 40 tpy of 
Sulfur dioxide emissions, 40 tpy of Nitrogen oxide emissions, or 40 tpy 
of VOC emissions, to the extent that any such pollutant is defined as a 
precursor for PM2.5 in paragraph (a)(1)(xxxvii) of this 
section.

    (B) Notwithstanding the significant emissions rate for ozone in 
paragraph (a)(1)(x)(A) of this section, significant means, in reference 
to an emissions increase or a net emissions increase, any increase in 
actual emissions of volatile organic compounds that would result from 
any physical change in, or change in the method of operation of, a major 
stationary source locating in a serious or severe ozone nonattainment 
area that is subject to subpart 2, part D, title I of the Act, if such 
emissions increase of volatile organic compounds exceeds 25 tons per 
year.
    (C) For the purposes of applying the requirements of paragraph 
(a)(8) of this section to modifications at major stationary sources of 
nitrogen oxides located in an ozone nonattainment area or in an ozone 
transport region, the significant emission rates and other requirements 
for volatile organic compounds in paragraphs (a)(1)(x)(A), (B), and (E) 
of this section shall apply to nitrogen oxides emissions.
    (D) Notwithstanding the significant emissions rate for carbon 
monoxide

[[Page 236]]

under paragraph (a)(1)(x)(A) of this section, significant means, in 
reference to an emissions increase or a net emissions increase, any 
increase in actual emissions of carbon monoxide that would result from 
any physical change in, or change in the method of operation of, a major 
stationary source in a serious nonattainment area for carbon monoxide if 
such increase equals or exceeds 50 tons per year, provided the 
Administrator has determined that stationary sources contribute 
significantly to carbon monoxide levels in that area.
    (E) Notwithstanding the significant emissions rates for ozone under 
paragraphs (a)(1)(x)(A) and (B) of this section, any increase in actual 
emissions of volatile organic compounds from any emissions unit at a 
major stationary source of volatile organic compounds located in an 
extreme ozone nonattainment area that is subject to subpart 2, part D, 
title I of the Act shall be considered a significant net emissions 
increase.
    (F) For the purposes of applying the requirements of paragraph 
(a)(13) of this section to modifications at existing major stationary 
sources of Ammonia located in a PM2.5 nonattainment area, if 
the plan requires that the control requirements of this section apply to 
major stationary sources and major modifications of Ammonia as a 
regulated NSR pollutant (as a PM2.5 precursor), the plan 
shall also define ``significant'' for Ammonia for that area, subject to 
the approval of the Administrator.
    (xi) Allowable emissions means the emissions rate of a stationary 
source calculated using the maximum rated capacity of the source (unless 
the source is subject to federally enforceable limits which restrict the 
operating rate, or hours of operation, or both) and the most stringent 
of the following:
    (A) The applicable standards set forth in 40 CFR part 60 or 61;
    (B) Any applicable State Implementation Plan emissions limitation 
including those with a future compliance date; or
    (C) The emissions rate specified as a federally enforceable permit 
condition, including those with a future compliance date.
    (xii)(A) Actual emissions means the actual rate of emissions of a 
regulated NSR pollutant from an emissions unit, as determined in 
accordance with paragraphs (a)(1)(xii)(B) through (D) of this section, 
except that this definition shall not apply for calculating whether a 
significant emissions increase has occurred, or for establishing a PAL 
under paragraph (f) of this section. Instead, paragraphs (a)(1)(xxviii) 
and (xxxv) of this section shall apply for those purposes.
    (B) In general, actual emissions as of a particular date shall equal 
the average rate, in tons per year, at which the unit actually emitted 
the pollutant during a consecutive 24-month period which precedes the 
particular date and which is representative of normal source operation. 
The reviewing authority shall allow the use of a different time period 
upon a determination that it is more representative of normal source 
operation. Actual emissions shall be calculated using the unit's actual 
operating hours, production rates, and types of materials processed, 
stored, or combusted during the selected time period.
    (C) The reviewing authority may presume that source-specific 
allowable emissions for the unit are equivalent to the actual emissions 
of the unit.
    (D) For any emissions unit that has not begun normal operations on 
the particular date, actual emissions shall equal the potential to emit 
of the unit on that date.
    (xiii) Lowest achievable emission rate (LAER) means, for any source, 
the more stringent rate of emissions based on the following:
    (A) The most stringent emissions limitation which is contained in 
the implementation plan of any State for such class or category of 
stationary source, unless the owner or operator of the proposed 
stationary source demonstrates that such limitations are not achievable; 
or
    (B) The most stringent emissions limitation which is achieved in 
practice by such class or category of stationary sources. This 
limitation, when applied to a modification, means the lowest achievable 
emissions rate for

[[Page 237]]

the new or modified emissions units within or stationary source. In no 
event shall the application of the term permit a proposed new or 
modified stationary source to emit any pollutant in excess of the amount 
allowable under an applicable new source standard of performance.
    (xiv) Federally enforceable means all limitations and conditions 
which are enforceable by the Administrator, including those requirements 
developed pursuant to 40 CFR parts 60 and 61, requirements within any 
applicable State implementation plan, any permit requirements 
established pursuant to 40 CFR 52.21 or under regulations approved 
pursuant to 40 CFR part 51, subpart I, including operating permits 
issued under an EPA-approved program that is incorporated into the State 
implementation plan and expressly requires adherence to any permit 
issued under such program.
    (xv) Begin actual construction means in general, initiation of 
physical on-site construction activities on an emissions unit which are 
of a permanent nature. Such activities include, but are not limited to, 
installation of building supports and foundations, laying of underground 
pipework, and construction of permanent storage structures. With respect 
to a change in method of operating this term refers to those on-site 
activities other than preparatory activities which mark the initiation 
of the change.
    (xvi) Commence as applied to construction of a major stationary 
source or major modification means that the owner or operator has all 
necessary preconstruction approvals or permits and either has:
    (A) Begun, or caused to begin, a continuous program of actual on-
site construction of the source, to be completed within a reasonable 
time; or
    (B) Entered into binding agreements or contractual obligations, 
which cannot be canceled or modified without substantial loss to the 
owner or operator, to undertake a program of actual construction of the 
source to be completed within a reasonable time.
    (xvii) Necessary preconstruction approvals or permits means those 
Federal air quality control laws and regulations and those air quality 
control laws and regulations which are part of the applicable State 
Implementation Plan.
    (xviii) Construction means any physical change or change in the 
method of operation (including fabrication, erection, installation, 
demolition, or modification of an emissions unit) that would result in a 
change in emissions.
    (xix) Volatile organic compounds (VOC) is as defined in Sec. 
51.100(s) of this part.
    (xx) Electric utility steam generating unit means any steam electric 
generating unit that is constructed for the purpose of supplying more 
than one-third of its potential electric output capacity and more than 
25 MW electrical output to any utility power distribution system for 
sale. Any steam supplied to a steam distribution system for the purpose 
of providing steam to a steam-electric generator that would produce 
electrical energy for sale is also considered in determining the 
electrical energy output capacity of the affected facility.
    (xxi) Replacement unit means an emissions unit for which all the 
criteria listed in paragraphs (a)(1)(xxi)(A) through (D) of this section 
are met. No creditable emission reductions shall be generated from 
shutting down the existing emissions unit that is replaced.
    (A) The emissions unit is a reconstructed unit within the meaning of 
Sec. 60.15(b)(1) of this chapter, or the emissions unit completely 
takes the place of an existing emissions unit.
    (B) The emissions unit is identical to or functionally equivalent to 
the replaced emissions unit.
    (C) The replacement does not alter the basic design parameters (as 
discussed in paragraph (h)(2) of this section) of the process unit.
    (D) The replaced emissions unit is permanently removed from the 
major stationary source, otherwise permanently disabled, or permanently 
barred from operation by a permit that is enforceable as a practical 
matter. If the replaced emissions unit is brought back into operation, 
it shall constitute a new emissions unit.
    (xxii) Temporary clean coal technology demonstration project means a 
clean coal technology demonstration project that is operated for a 
period of 5 years or less, and which complies with the State 
Implementation Plan for the

[[Page 238]]

State in which the project is located and other requirements necessary 
to attain and maintain the national ambient air quality standards during 
the project and after it is terminated.
    (xxiii) Clean coal technology means any technology, including 
technologies applied at the precombustion, combustion, or post 
combustion stage, at a new or existing facility which will achieve 
significant reductions in air emissions of sulfur dioxide or oxides of 
nitrogen associated with the utilization of coal in the generation of 
electricity, or process steam which was not in widespread use as of 
November 15, 1990.
    (xxiv) Clean coal technology demonstration project means a project 
using funds appropriated under the heading ``Department of Energy-Clean 
Coal Technology,'' up to a total amount of $2,500,000,000 for commercial 
demonstration of clean coal technology, or similar projects funded 
through appropriations for the Environmental Protection Agency. The 
Federal contribution for a qualifying project shall be at least 20 
percent of the total cost of the demonstration project.
    (xxv) [Reserved]
    (xxvi) Pollution prevention means any activity that through process 
changes, product reformulation or redesign, or substitution of less 
polluting raw materials, eliminates or reduces the release of air 
pollutants (including fugitive emissions) and other pollutants to the 
environment prior to recycling, treatment, or disposal; it does not mean 
recycling (other than certain ``in-process recycling'' practices), 
energy recovery, treatment, or disposal.
    (xxvii) Significant emissions increase means, for a regulated NSR 
pollutant, an increase in emissions that is significant (as defined in 
paragraph (a)(1)(x) of this section) for that pollutant.
    (xxviii)(A) Projected actual emissions means, the maximum annual 
rate, in tons per year, at which an existing emissions unit is projected 
to emit a regulated NSR pollutant in any one of the 5 years (12-month 
period) following the date the unit resumes regular operation after the 
project, or in any one of the 10 years following that date, if the 
project involves increasing the emissions unit's design capacity or its 
potential to emit of that regulated NSR pollutant and full utilization 
of the unit would result in a significant emissions increase or a 
significant net emissions increase at the major stationary source.
    (B) In determining the projected actual emissions under paragraph 
(a)(1)(xxviii)(A) of this section before beginning actual construction, 
the owner or operator of the major stationary source:
    (1) Shall consider all relevant information, including but not 
limited to, historical operational data, the company's own 
representations, the company's expected business activity and the 
company's highest projections of business activity, the company's 
filings with the State or Federal regulatory authorities, and compliance 
plans under the approved plan; and
    (2) Shall include fugitive emissions to the extent quantifiable, and 
emissions associated with startups, shutdowns, and malfunctions; and
    (3) Shall exclude, in calculating any increase in emissions that 
results from the particular project, that portion of the unit's 
emissions following the project that an existing unit could have 
accommodated during the consecutive 24-month period used to establish 
the baseline actual emissions under paragraph (a)(1)(xxxv) of this 
section and that are also unrelated to the particular project, including 
any increased utilization due to product demand growth; or,
    (4) In lieu of using the method set out in paragraphs 
(a)(1)(xxviii)(B)(1) through (3) of this section, may elect to use the 
emissions unit's potential to emit, in tons per year, as defined under 
paragraph (a)(1)(iii) of this section.
    (xxix) [Reserved]
    (xxx) Nonattainment major new source review (NSR) program means a 
major source preconstruction permit program that has been approved by 
the Administrator and incorporated into the plan to implement the 
requirements of this section, or a program that implements part 51, 
appendix S, Sections I through VI of this chapter. Any permit issued 
under such a program is a major NSR permit.

[[Page 239]]

    (xxxi) Continuous emissions monitoring system (CEMS) means all of 
the equipment that may be required to meet the data acquisition and 
availability requirements of this section, to sample, condition (if 
applicable), analyze, and provide a record of emissions on a continuous 
basis.
    (xxxii) Predictive emissions monitoring system (PEMS) means all of 
the equipment necessary to monitor process and control device 
operational parameters (for example, control device secondary voltages 
and electric currents) and other information (for example, gas flow 
rate, O2 or CO2 concentrations), and calculate and 
record the mass emissions rate (for example, lb/hr) on a continuous 
basis.
    (xxxiii) Continuous parameter monitoring system (CPMS) means all of 
the equipment necessary to meet the data acquisition and availability 
requirements of this section, to monitor process and control device 
operational parameters (for example, control device secondary voltages 
and electric currents) and other information (for example, gas flow 
rate, O2 or CO2 concentrations), and to record 
average operational parameter value(s) on a continuous basis.
    (xxxiv) Continuous emissions rate monitoring system (CERMS) means 
the total equipment required for the determination and recording of the 
pollutant mass emissions rate (in terms of mass per unit of time).
    (xxxv) Baseline actual emissions means the rate of emissions, in 
tons per year, of a regulated NSR pollutant, as determined in accordance 
with paragraphs (a)(1)(xxxv)(A) through (D) of this section.
    (A) For any existing electric utility steam generating unit, 
baseline actual emissions means the average rate, in tons per year, at 
which the unit actually emitted the pollutant during any consecutive 24-
month period selected by the owner or operator within the 5-year period 
immediately preceding when the owner or operator begins actual 
construction of the project. The reviewing authority shall allow the use 
of a different time period upon a determination that it is more 
representative of normal source operation.
    (1) The average rate shall include fugitive emissions to the extent 
quantifiable, and emissions associated with startups, shutdowns, and 
malfunctions.
    (2) The average rate shall be adjusted downward to exclude any non-
compliant emissions that occurred while the source was operating above 
any emission limitation that was legally enforceable during the 
consecutive 24-month period.
    (3) For a regulated NSR pollutant, when a project involves multiple 
emissions units, only one consecutive 24-month period must be used to 
determine the baseline actual emissions for the emissions units being 
changed. A different consecutive 24-month period can be used for each 
regulated NSR pollutant.
    (4) The average rate shall not be based on any consecutive 24-month 
period for which there is inadequate information for determining annual 
emissions, in tons per year, and for adjusting this amount if required 
by paragraph (a)(1)(xxxv)(A)(2) of this section.
    (B) For an existing emissions unit (other than an electric utility 
steam generating unit), baseline actual emissions means the average 
rate, in tons per year, at which the emissions unit actually emitted the 
pollutant during any consecutive 24-month period selected by the owner 
or operator within the 10-year period immediately preceding either the 
date the owner or operator begins actual construction of the project, or 
the date a complete permit application is received by the reviewing 
authority for a permit required either under this section or under a 
plan approved by the Administrator, whichever is earlier, except that 
the 10-year period shall not include any period earlier than November 
15, 1990.
    (1) The average rate shall include fugitive emissions to the extent 
quantifiable, and emissions associated with startups, shutdowns, and 
malfunctions.
    (2) The average rate shall be adjusted downward to exclude any non-
compliant emissions that occurred while the source was operating above 
an emission limitation that was legally enforceable during the 
consecutive 24-month period.

[[Page 240]]

    (3) The average rate shall be adjusted downward to exclude any 
emissions that would have exceeded an emission limitation with which the 
major stationary source must currently comply, had such major stationary 
source been required to comply with such limitations during the 
consecutive 24-month period. However, if an emission limitation is part 
of a maximum achievable control technology standard that the 
Administrator proposed or promulgated under part 63 of this chapter, the 
baseline actual emissions need only be adjusted if the State has taken 
credit for such emissions reductions in an attainment demonstration or 
maintenance plan consistent with the requirements of paragraph 
(a)(3)(ii)(G) of this section.
    (4) For a regulated NSR pollutant, when a project involves multiple 
emissions units, only one consecutive 24-month period must be used to 
determine the baseline actual emissions for the emissions units being 
changed. A different consecutive 24-month period can be used For each 
regulated NSR pollutant.
    (5) The average rate shall not be based on any consecutive 24-month 
period for which there is inadequate information for determining annual 
emissions, in tons per year, and for adjusting this amount if required 
by paragraphs (a)(1)(xxxv)(B)(2) and (3) of this section.
    (C) For a new emissions unit, the baseline actual emissions for 
purposes of determining the emissions increase that will result from the 
initial construction and operation of such unit shall equal zero; and 
thereafter, for all other purposes, shall equal the unit's potential to 
emit.
    (D) For a PAL for a major stationary source, the baseline actual 
emissions shall be calculated for existing electric utility steam 
generating units in accordance with the procedures contained in 
paragraph (a)(1)(xxxv)(A) of this section, for other existing emissions 
units in accordance with the procedures contained in paragraph 
(a)(1)(xxxv)(B) of this section, and for a new emissions unit in 
accordance with the procedures contained in paragraph (a)(1)(xxxv)(C) of 
this section.
    (xxxvi) [Reserved]
    (xxxvii) Regulated NSR pollutant, for purposes of this section, 
means the following:
    (A) Nitrogen oxides or any volatile organic compounds;
    (B) Any pollutant for which a national ambient air quality standard 
has been promulgated;
    (C) Any pollutant that is identified under this paragraph 
(a)(1)(xxxvii)(C) as a constituent or precursor of a general pollutant 
listed under paragraph (a)(1)(xxxvii)(A) or (B) of this section, 
provided that such constituent or precursor pollutant may only be 
regulated under NSR as part of regulation of the general pollutant. 
Precursors identified by the Administrator for purposes of NSR are the 
following:
    (1) Volatile organic compounds and nitrogen oxides are precursors to 
ozone in all ozone nonattainment areas.
    (2) Sulfur dioxide, Nitrogen oxides, Volatile organic compounds and 
Ammonia are precursors to PM2.5 in any PM2.5 
nonattainment area.
    (D) PM2.5 emissions and PM10 emissions shall 
include gaseous emissions from a source or activity which condense to 
form particulate matter at ambient temperatures. On or after January 1, 
2011 (or any earlier date established in the upcoming rulemaking 
codifying test methods), such condensable particulate matter shall be 
accounted for in applicability determinations and in establishing 
emissions limitations for PM2.5 and PM10 in 
nonattainment major NSR permits. Compliance with emissions limitations 
for PM2.5 and PM10 issued prior to this date shall 
not be based on condensable particulate matter unless required by the 
terms and conditions of the permit or the applicable implementation 
plan. Applicability determinations made prior to this date without 
accounting for condensable particulate matter shall not be considered in 
violation of this section unless the applicable implementation plan 
required condensable particulate matter to be included.
    (xxxviii) Reviewing authority means the State air pollution control 
agency, local agency, other State agency, Indian tribe, or other agency 
authorized by the Administrator to carry out a permit program under this 
section and

[[Page 241]]

Sec. 51.166, or the Administrator in the case of EPA-implemented permit 
programs under Sec. 52.21.
    (xxxix) Project means a physical change in, or change in the method 
of operation of, an existing major stationary source.
    (xl) Best available control technology (BACT) means an emissions 
limitation (including a visible emissions standard) based on the maximum 
degree of reduction for each regulated NSR pollutant which would be 
emitted from any proposed major stationary source or major modification 
which the reviewing authority, on a case-by-case basis, taking into 
account energy, environmental, and economic impacts and other costs, 
determines is achievable for such source or modification through 
application of production processes or available methods, systems, and 
techniques, including fuel cleaning or treatment or innovative fuel 
combustion techniques for control of such pollutant. In no event shall 
application of best available control technology result in emissions of 
any pollutant which would exceed the emissions allowed by any applicable 
standard under 40 CFR part 60 or 61. If the reviewing authority 
determines that technological or economic limitations on the application 
of measurement methodology to a particular emissions unit would make the 
imposition of an emissions standard infeasible, a design, equipment, 
work practice, operational standard, or combination thereof, may be 
prescribed instead to satisfy the requirement for the application of 
BACT. Such standard shall, to the degree possible, set forth the 
emissions reduction achievable by implementation of such design, 
equipment, work practice or operation, and shall provide for compliance 
by means which achieve equivalent results.
    (xli) Prevention of Significant Deterioration (PSD) permit means any 
permit that is issued under a major source preconstruction permit 
program that has been approved by the Administrator and incorporated 
into the plan to implement the requirements of Sec. 51.166 of this 
chapter, or under the program in Sec. 52.21 of this chapter.
    (xlii) Federal Land Manager means, with respect to any lands in the 
United States, the Secretary of the department with authority over such 
lands.
    (xliii)(A) In general, process unit means any collection of 
structures and/or equipment that processes, assembles, applies, blends, 
or otherwise uses material inputs to produce or store an intermediate or 
a completed product. A single stationary source may contain more than 
one process unit, and a process unit may contain more than one emissions 
unit.
    (B) Pollution control equipment is not part of the process unit, 
unless it serves a dual function as both process and control equipment. 
Administrative and warehousing facilities are not part of the process 
unit.
    (C) For replacement cost purposes, components shared between two or 
more process units are proportionately allocated based on capacity.
    (D) The following list identifies the process units at specific 
categories of stationary sources.
    (1) For a steam electric generating facility, the process unit 
consists of those portions of the plant that contribute directly to the 
production of electricity. For example, at a pulverized coal-fired 
facility, the process unit would generally be the combination of those 
systems from the coal receiving equipment through the emission stack 
(excluding post-combustion pollution controls), including the coal 
handling equipment, pulverizers or coal crushers, feedwater heaters, ash 
handling, boiler, burners, turbine-generator set, condenser, cooling 
tower, water treatment system, air preheaters, and operating control 
systems. Each separate generating unit is a separate process unit.
    (2) For a petroleum refinery, there are several categories of 
process units: those that separate and/or distill petroleum feedstocks; 
those that change molecular structures; petroleum treating processes; 
auxiliary facilities, such as steam generators and hydrogen production 
units; and those that load, unload, blend or store intermediate or 
completed products.
    (3) For an incinerator, the process unit would consist of components 
from the feed pit or refuse pit to the stack,

[[Page 242]]

including conveyors, combustion devices, heat exchangers and steam 
generators, quench tanks, and fans.

    Note to paragraph (a)(1)(xliii): By a court order on December 24, 
2003, this paragraph (a)(1)(xliii) is stayed indefinitely. The stayed 
provisions will become effective immediately if the court terminates the 
stay. At that time, EPA will publish a document in the Federal Register 
advising the public of the termination of the stay.

    (xliv) Functionally equivalent component means a component that 
serves the same purpose as the replaced component.

    Note to paragraph (a)(1)(xliv): By a court order on December 24, 
2003, this paragraph (a)(1)(xliv) is stayed indefinitely. The stayed 
provisions will become effective immediately if the court terminates the 
stay. At that time, EPA will publish a document in the Federal Register 
advising the public of the termination of the stay.

    (xlv) Fixed capital cost means the capital needed to provide all the 
depreciable components. ``Depreciable components'' refers to all 
components of fixed capital cost and is calculated by subtracting land 
and working capital from the total capital investment, as defined in 
paragraph (a)(1)(xlvi) of this section.

    Note to paragraph (a)(1)(xlv): By a court order on December 24, 
2003, this paragraph (a)(1)(xlv) is stayed indefinitely. The stayed 
provisions will become effective immediately if the court terminates the 
stay. At that time, EPA will publish a document in the Federal Register 
advising the public of the termination of the stay.

    (xlvi) Total capital investment means the sum of the following: All 
costs required to purchase needed process equipment (purchased equipment 
costs); the costs of labor and materials for installing that equipment 
(direct installation costs); the costs of site preparation and 
buildings; other costs such as engineering, construction and field 
expenses, fees to contractors, startup and performance tests, and 
contingencies (indirect installation costs); land for the process 
equipment; and working capital for the process equipment.

    Note to paragraph (a)(1)(xlvi): By a court order on December 24, 
2003, this paragraph (a)(1)(xlvi) is stayed indefinitely. The stayed 
provisions will become effective immediately if the court terminates the 
stay. At that time, EPA will publish a document in the Federal Register 
advising the public of the termination of the stay.

    (2) Applicability procedures. (i) Each plan shall adopt a 
preconstruction review program to satisfy the requirements of sections 
172(c)(5) and 173 of the Act for any area designated nonattainment for 
any national ambient air quality standard under subpart C of 40 CFR part 
81. Such a program shall apply to any new major stationary source or 
major modification that is major for the pollutant for which the area is 
designated nonattainment under section 107(d)(1)(A)(i) of the Act, if 
the stationary source or modification would locate anywhere in the 
designated nonattainment area. Different pollutants, including 
individual precursors, are not summed to determine applicability of a 
major stationary source or major modification.
    (ii) Each plan shall use the specific provisions of paragraphs 
(a)(2)(ii)(A) through (F) of this section. Deviations from these 
provisions will be approved only if the State specifically demonstrates 
that the submitted provisions are more stringent than or at least as 
stringent in all respects as the corresponding provisions in paragraphs 
(a)(2)(ii)(A) through (F) of this section.
    (A) Except as otherwise provided in paragraphs (a)(2)(iii) and (iv) 
of this section, and consistent with the definition of major 
modification contained in paragraph (a)(1)(v)(A) of this section, a 
project is a major modification for a regulated NSR pollutant (as 
defined in paragraph (a)(1)(xxxvii) of this section) if it causes two 
types of emissions increases--a significant emissions increase (as 
defined in paragraph (a)(1)(xxvii) of this section), and a significant 
net emissions increase (as defined in paragraphs (a)(1)(vi) and (x) of 
this section). The project is not a major modification if it does not 
cause a significant emissions increase. If the project causes a 
significant emissions increase, then the project is a major modification 
only if it also results in a significant net emissions increase.
    (B) The procedure for calculating (before beginning actual 
construction)

[[Page 243]]

whether a significant emissions increase (i.e., the first step of the 
process) will occur depends upon the type of emissions units being 
modified, according to paragraphs (a)(2)(ii)(C) through (F) of this 
section. The procedure for calculating (before beginning actual 
construction) whether a significant net emissions increase will occur at 
the major stationary source (i.e., the second step of the process) is 
contained in the definition in paragraph (a)(1)(vi) of this section. 
Regardless of any such preconstruction projections, a major modification 
results if the project causes a significant emissions increase and a 
significant net emissions increase.
    (C) Actual-to-projected-actual applicability test for projects that 
only involve existing emissions units. A significant emissions increase 
of a regulated NSR pollutant is projected to occur if the sum of the 
difference between the projected actual emissions (as defined in 
paragraph (a)(1)(xxviii) of this section) and the baseline actual 
emissions (as defined in paragraphs (a)(1)(xxxv)(A) and (B) of this 
section, as applicable), for each existing emissions unit, equals or 
exceeds the significant amount for that pollutant (as defined in 
paragraph (a)(1)(x) of this section).
    (D) Actual-to-potential test for projects that only involve 
construction of a new emissions unit(s). A significant emissions 
increase of a regulated NSR pollutant is projected to occur if the sum 
of the difference between the potential to emit (as defined in paragraph 
(a)(1)(iii) of this section) from each new emissions unit following 
completion of the project and the baseline actual emissions (as defined 
in paragraph (a)(1)(xxxv)(C) of this section) of these units before the 
project equals or exceeds the significant amount for that pollutant (as 
defined in paragraph (a)(1)(x) of this section).
    (E) [Reserved]
    (F) Hybrid test for projects that involve multiple types of 
emissions units. A significant emissions increase of a regulated NSR 
pollutant is projected to occur if the sum of the difference for all 
emissions units, using the method specified in paragraphs (a)(2)(ii)(C) 
through (D) of this section as applicable with respect to each emissions 
unit, equals or exceeds the significant amount for that pollutant (as 
defined in paragraph (a)(1)(x) of this section).
    (G) The ``sum of the difference'' as used in paragraphs (C), (D) and 
(F) of this section shall include both increases and decreases in 
emissions calculated in accordance with those paragraphs.
    (3)(i) Each plan shall provide that for sources and modifications 
subject to any preconstruction review program adopted pursuant to this 
subsection the baseline for determining credit for emissions reductions 
is the emissions limit under the applicable State Implementation Plan in 
effect at the time the application to construct is filed, except that 
the offset baseline shall be the actual emissions of the source from 
which offset credit is obtained where;
    (A) The demonstration of reasonable further progress and attainment 
of ambient air quality standards is based upon the actual emissions of 
sources located within a designated nonattainment area for which the 
preconstruction review program was adopted; or
    (B) The applicable State Implementation Plan does not contain an 
emissions limitation for that source or source category.
    (ii) The plan shall further provide that:
    (A) Where the emissions limit under the applicable State 
Implementation Plan allows greater emissions than the potential to emit 
of the source, emissions offset credit will be allowed only for control 
below this potential;
    (B) For an existing fuel combustion source, credit shall be based on 
the allowable emissions under the applicable State Implementation Plan 
for the type of fuel being burned at the time the application to 
construct is filed. If the existing source commits to switch to a 
cleaner fuel at some future date, emissions offset credit based on the 
allowable (or actual) emissions for the fuels involved is not 
acceptable, unless the permit is conditioned to require the use of a 
specified alternative control measure which would achieve the same 
degree of emissions reduction should the source switch back to a dirtier 
fuel at some later date. The reviewing authority should ensure that

[[Page 244]]

adequate long-term supplies of the new fuel are available before 
granting emissions offset credit for fuel switches,
    (C)(1) Emissions reductions achieved by shutting down an existing 
emission unit or curtailing production or operating hours may be 
generally credited for offsets if they meet the requirements in 
paragraphs (a)(3)(ii)(C)(1)(i) through (ii) of this section.
    (i) Such reductions are surplus, permanent, quantifiable, and 
federally enforceable.
    (ii) The shutdown or curtailment occurred after the last day of the 
base year for the SIP planning process. For purposes of this paragraph, 
a reviewing authority may choose to consider a prior shutdown or 
curtailment to have occurred after the last day of the base year if the 
projected emissions inventory used to develop the attainment 
demonstration explicitly includes the emissions from such previously 
shutdown or curtailed emission units. However, in no event may credit be 
given for shutdowns that occurred before August 7, 1977.
    (2) Emissions reductions achieved by shutting down an existing 
emissions unit or curtailing production or operating hours and that do 
not meet the requirements in paragraph (a)(3)(ii)(C)(1)(ii) of this 
section may be generally credited only if:
    (i) The shutdown or curtailment occurred on or after the date the 
construction permit application is filed; or
    (ii) The applicant can establish that the proposed new emissions 
unit is a replacement for the shutdown or curtailed emissions unit, and 
the emissions reductions achieved by the shutdown or curtailment met the 
requirements of paragraph (a)(3)(ii)(C)(1)(i) of this section.
    (D) No emissions credit may be allowed for replacing one hydrocarbon 
compound with another of lesser reactivity, except for those compounds 
listed in Table 1 of EPA's ``Recommended Policy on Control of Volatile 
Organic Compounds'' (42 FR 35314, July 8, 1977; (This document is also 
available from Mr. Ted Creekmore, Office of Air Quality Planning and 
Standards, (MD-15) Research Triangle Park, NC 27711.))
    (E) All emission reductions claimed as offset credit shall be 
federally enforceable;
    (F) Procedures relating to the permissible location of offsetting 
emissions shall be followed which are at least as stringent as those set 
out in 40 CFR part 51 appendix S section IV.D.
    (G) Credit for an emissions reduction can be claimed to the extent 
that the reviewing authority has not relied on it in issuing any permit 
under regulations approved pursuant to 40 CFR part 51 subpart I or the 
State has not relied on it in demonstration attainment or reasonable 
further progress.
    (H) [Reserved]
    (I) [Reserved]
    (J) The total tonnage of increased emissions, in tons per year, 
resulting from a major modification that must be offset in accordance 
with section 173 of the Act shall be determined by summing the 
difference between the allowable emissions after the modification (as 
defined by paragraph (a)(1)(xi) of this section) and the actual 
emissions before the modification (as defined in paragraph (a)(1)(xii) 
of this section) for each emissions unit.
    (4) Each plan may provide that the provisions of this paragraph do 
not apply to a source or modification that would be a major stationary 
source or major modification only if fugitive emissions, to the extent 
quantifiable, are considered in calculating the potential to emit of the 
stationary source or modification and the source does not belong to any 
of the following categories:
    (i) Coal cleaning plants (with thermal dryers);
    (ii) Kraft pulp mills;
    (iii) Portland cement plants;
    (iv) Primary zinc smelters;
    (v) Iron and steel mills;
    (vi) Primary aluminum ore reduction plants;
    (vii) Primary copper smelters;
    (viii) Municipal incinerators capable of charging more than 250 tons 
of refuse per day;
    (ix) Hydrofluoric, sulfuric, or citric acid plants;
    (x) Petroleum refineries;
    (xi) Lime plants;
    (xii) Phosphate rock processing plants;

[[Page 245]]

    (xiii) Coke oven batteries;
    (xiv) Sulfur recovery plants;
    (xv) Carbon black plants (furnace process);
    (xvi) Primary lead smelters;
    (xvii) Fuel conversion plants;
    (xviii) Sintering plants;
    (xix) Secondary metal production plants;
    (xx) Chemical process plants--The term chemical processing plant 
shall not include ethanol production facilities that produce ethanol by 
natural fermentation included in NAICS codes 325193 or 312140;
    (xxi) Fossil-fuel boilers (or combination thereof) totaling more 
than 250 million British thermal units per hour heat input;
    (xxii) Petroleum storage and transfer units with a total storage 
capacity exceeding 300,000 barrels;
    (xxiii) Taconite ore processing plants;
    (xxiv) Glass fiber processing plants;
    (xxv) Charcoal production plants;
    (xxvi) Fossil fuel-fired steam electric plants of more than 250 
million British thermal units per hour heat input;
    (xxvii) Any other stationary source category which, as of August 7, 
1980, is being regulated under section 111 or 112 of the Act.
    (5) Each plan shall include enforceable procedures to provide that:
    (i) Approval to construct shall not relieve any owner or operator of 
the responsibility to comply fully with applicable provision of the plan 
and any other requirements under local, State or Federal law.
    (ii) At such time that a particular source or modification becomes a 
major stationary source or major modification solely by virtue of a 
relaxation in any enforcement limitation which was established after 
August 7, 1980, on the capacity of the source or modification otherwise 
to emit a pollutant, such as a restriction on hours of operation, then 
the requirements of regulations approved pursuant to this section shall 
apply to the source or modification as though construction had not yet 
commenced on the source or modification;
    (6) Each plan shall provide that, except as otherwise provided in 
paragraph (a)(6)(vi) of this section, the following specific provisions 
apply with respect to any regulated NSR pollutant emitted from projects 
at existing emissions units at a major stationary source (other than 
projects at a source with a PAL) in circumstances where there is a 
reasonable possibility, within the meaning of paragraph (a)(6)(vi) of 
this section, that a project that is not a part of a major modification 
may result in a significant emissions increase of such pollutant, and 
the owner or operator elects to use the method specified in paragraphs 
(a)(1)(xxviii)(B)(1) through (3) of this section for calculating 
projected actual emissions. Deviations from these provisions will be 
approved only if the State specifically demonstrates that the submitted 
provisions are more stringent than or at least as stringent in all 
respects as the corresponding provisions in paragraphs (a)(6)(i) through 
(vi) of this section.
    (i) Before beginning actual construction of the project, the owner 
or operator shall document and maintain a record of the following 
information:
    (A) A description of the project;
    (B) Identification of the emissions unit(s) whose emissions of a 
regulated NSR pollutant could be affected by the project; and
    (C) A description of the applicability test used to determine that 
the project is not a major modification for any regulated NSR pollutant, 
including the baseline actual emissions, the projected actual emissions, 
the amount of emissions excluded under paragraph (a)(1)(xxviii)(B)(3) of 
this section and an explanation for why such amount was excluded, and 
any netting calculations, if applicable.
    (ii) If the emissions unit is an existing electric utility steam 
generating unit, before beginning actual construction, the owner or 
operator shall provide a copy of the information set out in paragraph 
(a)(6)(i) of this section to the reviewing authority. Nothing in this 
paragraph (a)(6)(ii) shall be construed to require the owner or operator 
of such a unit to obtain any determination from the reviewing authority 
before beginning actual construction.
    (iii) The owner or operator shall monitor the emissions of any 
regulated NSR pollutant that could increase as a

[[Page 246]]

result of the project and that is emitted by any emissions units 
identified in paragraph (a)(6)(i)(B) of this section; and calculate and 
maintain a record of the annual emissions, in tons per year on a 
calendar year basis, for a period of 5 years following resumption of 
regular operations after the change, or for a period of 10 years 
following resumption of regular operations after the change if the 
project increases the design capacity or potential to emit of that 
regulated NSR pollutant at such emissions unit.
    (iv) If the unit is an existing electric utility steam generating 
unit, the owner or operator shall submit a report to the reviewing 
authority within 60 days after the end of each year during which records 
must be generated under paragraph (a)(6)(iii) of this section setting 
out the unit's annual emissions during the year that preceded submission 
of the report.
    (v) If the unit is an existing unit other than an electric utility 
steam generating unit, the owner or operator shall submit a report to 
the reviewing authority if the annual emissions, in tons per year, from 
the project identified in paragraph (a)(6)(i) of this section, exceed 
the baseline actual emissions (as documented and maintained pursuant to 
paragraph (a)(6)(i)(C) of this section, by a significant amount (as 
defined in paragraph (a)(1)(x) of this section) for that regulated NSR 
pollutant, and if such emissions differ from the preconstruction 
projection as documented and maintained pursuant to paragraph 
(a)(6)(i)(C) of this section. Such report shall be submitted to the 
reviewing authority within 60 days after the end of such year. The 
report shall contain the following:
    (A) The name, address and telephone number of the major stationary 
source;
    (B) The annual emissions as calculated pursuant to paragraph 
(a)(6)(iii) of this section; and
    (C) Any other information that the owner or operator wishes to 
include in the report (e.g., an explanation as to why the emissions 
differ from the preconstruction projection).
    (vi) A ``reasonable possibility'' under paragraph (a)(6) of this 
section occurs when the owner or operator calculates the project to 
result in either:
    (A) A projected actual emissions increase of at least 50 percent of 
the amount that is a ``significant emissions increase,'' as defined 
under paragraph (a)(1)(xxvii) of this section (without reference to the 
amount that is a significant net emissions increase), for the regulated 
NSR pollutant; or
    (B) A projected actual emissions increase that, added to the amount 
of emissions excluded under paragraph (a)(1)(xxviii)(B)(3), sums to at 
least 50 percent of the amount that is a ``significant emissions 
increase,'' as defined under paragraph (a)(1)(xxvii) of this section 
(without reference to the amount that is a significant net emissions 
increase), for the regulated NSR pollutant. For a project for which a 
reasonable possibility occurs only within the meaning of paragraph 
(a)(6)(vi)(B) of this section, and not also within the meaning of 
paragraph (a)(6)(vi)(A) of this section, then provisions (a)(6)(ii) 
through (v) do not apply to the project.
    (7) Each plan shall provide that the owner or operator of the source 
shall make the information required to be documented and maintained 
pursuant to paragraph (a)(6) of this section available for review upon a 
request for inspection by the reviewing authority or the general public 
pursuant to the requirements contained in Sec. 70.4(b)(3)(viii) of this 
chapter.
    (8) The plan shall provide that the requirements of this section 
applicable to major stationary sources and major modifications of 
volatile organic compounds shall apply to nitrogen oxides emissions from 
major stationary sources and major modifications of nitrogen oxides in 
an ozone transport region or in any ozone nonattainment area, except in 
ozone nonattainment areas or in portions of an ozone transport region 
where the Administrator has granted a NOX waiver applying the 
standards set forth under section 182(f) of the Act and the waiver 
continues to apply.
    (9)(i) The plan shall require that in meeting the emissions offset 
requirements of paragraph (a)(3) of this section, the ratio of total 
actual emissions reductions to the emissions increase

[[Page 247]]

shall be at least 1:1 unless an alternative ratio is provided for the 
applicable nonattainment area in paragraphs (a)(9)(ii) through 
(a)(9)(iv) of this section.
    (ii) The plan shall require that in meeting the emissions offset 
requirements of paragraph (a)(3) of this section for ozone nonattainment 
areas that are subject to subpart 2, part D, title I of the Act, the 
ratio of total actual emissions reductions of VOC to the emissions 
increase of VOC shall be as follows:
    (A) In any marginal nonattainment area for ozone--at least 1.1:1;
    (B) In any moderate nonattainment area for ozone--at least 1.15:1;
    (C) In any serious nonattainment area for ozone--at least 1.2:1;
    (D) In any severe nonattainment area for ozone--at least 1.3:1 
(except that the ratio may be at least 1.2:1 if the approved plan also 
requires all existing major sources in such nonattainment area to use 
BACT for the control of VOC); and
    (E) In any extreme nonattainment area for ozone--at least 1.5:1 
(except that the ratio may be at least 1.2:1 if the approved plan also 
requires all existing major sources in such nonattainment area to use 
BACT for the control of VOC); and
    (iii) Notwithstanding the requirements of paragraph (a)(9)(ii) of 
this section for meeting the requirements of paragraph (a)(3) of this 
section, the ratio of total actual emissions reductions of VOC to the 
emissions increase of VOC shall be at least 1.15:1 for all areas within 
an ozone transport region that is subject to subpart 2, part D, title I 
of the Act, except for serious, severe, and extreme ozone nonattainment 
areas that are subject to subpart 2, part D, title I of the Act.
    (iv) The plan shall require that in meeting the emissions offset 
requirements of paragraph (a)(3) of this section for ozone nonattainment 
areas that are subject to subpart 1, part D, title I of the Act (but are 
not subject to subpart 2, part D, title I of the Act, including 8-hour 
ozone nonattainment areas subject to 40 CFR 51.902(b)), the ratio of 
total actual emissions reductions of VOC to the emissions increase of 
VOC shall be at least 1:1.
    (10) The plan shall require that the requirements of this section 
applicable to major stationary sources and major modifications of PM-10 
shall also apply to major stationary sources and major modifications of 
PM-10 precursors, except where the Administrator determines that such 
sources do not contribute significantly to PM-10 levels that exceed the 
PM-10 ambient standards in the area.
    (11) Interpollutant offsetting, or interpollutant trading or 
interprecursor trading or interprecursor offset substitution--The plan 
shall require that in meeting the emissions offset requirements of 
paragraph (a)(3) of this section, the emissions offsets obtained shall 
be for the same regulated NSR pollutant unless interprecursor offsetting 
is permitted for a particular pollutant as specified in this paragraph. 
(a)(3) of this section, the emissions offsets obtained shall be for the 
same regulated NSR pollutant unless interprecursor offsetting is 
permitted for a particular pollutant as specified in this paragraph.
    (i) The plan may allow the offset requirement in paragraph (a)(3) of 
this section for emissions of the ozone precursors NOX and 
VOC to be satisfied, where appropriate, by offsetting reductions of 
actual emissions of either of those precursors, if all other 
requirements contained in this section for such offsets are also 
satisfied.
    (A) The plan shall indicate whether such precursor substitutions for 
ozone precursors are to be based on an area-specific default ratio 
(default ratio) for the applicable ozone nonattainment area, established 
in regulations as part of the approved plan, or default IPT ratios for 
an applicable ozone nonattainment area established in advance by an air 
agency that are presumed to be appropriate for each permit application 
in the area, absent contrary information in the record of an individual 
permit application, or case-specific ratios established for individual 
permits.
    (B)(1) Where a state seeks to use a default IPT ratio that is not 
part of the approved plan, the plan shall include the following to 
authorize the development of a default ratio for a particular ozone 
nonattainment area, including a revised default ratio resulting from the

[[Page 248]]

periodic review required under paragraph (a)(11)(i)(B)(2) of this 
section:
    (i) A description of the model(s) that will be used to develop any 
default ratio;
    (ii) A description of the approach that will be used to analyze 
modeling data, ambient monitoring data, and emission inventory data to 
determine the sensitivity of an area to emissions of ozone precursors in 
the formation of ground-level ozone; and
    (iii) A description of the modeling demonstration that will be used 
to show that the default ratio provides an equivalent or greater air 
quality benefit with respect to ground level concentrations in the ozone 
nonattainment area than an offset of the emitted precursor would 
achieve.
    (2) The plan shall require that for any default ratio for ozone, the 
reviewing authority shall evaluate that ratio at least every 5 years to 
determine whether current conditions support the continued use of such 
ratio.
    (C) The plan shall require that, for any case-specific permit ratio 
for ozone proposed by a permit applicant to be used for a particular 
permit, the following information shall be submitted to the reviewing 
authority to support approval of the ratio:
    (1) The description of the air quality model(s) used to propose a 
case-specific ratio; and
    (2) the proposed ratio for the precursor substitution and 
accompanying calculations; and
    (3) a modeling demonstration showing that such ratio(s) as applied 
to the proposed project and credit source will provide an equivalent or 
greater air quality benefit with respect to ground level concentrations 
in the ozone nonattainment area than an offset of the emitted precursor 
would achieve.
    (ii) The plan may allow the offset requirements in paragraph (a)(3) 
of this section for direct PM2.5 emissions or emissions of 
precursors of PM2.5 to be satisfied by offsetting reductions 
in direct PM2.5 emissions or emissions of any 
PM2.5 precursor identified under paragraph (a)(1)(xxxvii)(C) 
of this section if such offsets comply with the interprecursor trading 
hierarchy and ratio established in the approved plan for a particular 
nonattainment area.
    (12) The plan shall require that in any area designated 
nonattainment for the 2008 ozone NAAQS and designated nonattainment for 
the 1997 ozone NAAQS on April 6, 2015 the requirements of this section 
applicable to major stationary sources and major modifications of ozone 
shall include the anti-backsliding requirements contained at Sec. 
51.1105.
    (13) The plan shall require that the control requirements of this 
section applicable to major stationary sources and major modifications 
of PM2.5 shall also apply to major stationary sources and 
major modifications of PM2.5 precursors in a PM2.5 
nonattainment area, except that a reviewing authority may exempt new 
major stationary sources and major modifications of a particular 
precursor from the requirements of this section for PM2.5 if 
the NNSR precursor demonstration submitted to and approved by the 
Administrator shows that such sources do not contribute significantly to 
PM2.5 levels that exceed the standard in the area. Any 
demonstration submitted for the Administrator's review must meet the 
conditions for a NNSR precursor demonstration as set forth in Sec. 
51.1006(a)(3).
    (b)(1) Each plan shall include a preconstruction review permit 
program or its equivalent to satisfy the requirements of section 
110(a)(2)(D)(i) of the Act for any new major stationary source or major 
modification as defined in paragraphs (a)(1) (iv) and (v) of this 
section. Such a program shall apply to any such source or modification 
that would locate in any area designated as attainment or unclassifiable 
for any national ambient air quality standard pursuant to section 107 of 
the Act, when it would cause or contribute to a violation of any 
national ambient air quality standard.
    (2) A major source or major modification will be considered to cause 
or contribute to a violation of a national ambient air quality standard 
when such source or modification would, at a minimum, exceed the 
following significance levels at any locality that does not or would not 
meet the applicable national standard:

[[Page 249]]



----------------------------------------------------------------------------------------------------------------
                                                                     Averaging time (hours)
          Pollutant                 Annual     -----------------------------------------------------------------
                                                       24               8                3               1
----------------------------------------------------------------------------------------------------------------
SO2..........................  1.0 [micro]g/    5 [micro]g/m\3\  ...............  25 [micro]g/
                                m\3\                                               m\3\
PM10.........................  1.0 [micro]g/    5 [micro]g/m\3\
                                m\3\
PM2.5........................  0.3 [micro]g/    1.2 [micro]g/
                                m\3\             m\3\
NO2..........................  1.0 [micro]g/
                                m\3\
CO...........................  ...............  ...............  0.5 mg/m\3\      ...............  2 mg/m\3\
----------------------------------------------------------------------------------------------------------------

    (3) Such a program may include a provision which allows a proposed 
major source or major modification subject to paragraph (b) of this 
section to reduce the impact of its emissions upon air quality by 
obtaining sufficient emission reductions to, at a minimum, compensate 
for its adverse ambient impact where the major source or major 
modification would otherwise cause or contribute to a violation of any 
national ambient air quality standard. The plan shall require that, in 
the absence of such emission reductions, the State or local agency shall 
deny the proposed construction.
    (4) The requirements of paragraph (b) of this section shall not 
apply to a major stationary source or major modification with respect to 
a particular pollutant if the owner or operator demonstrates that, as to 
that pollutant, the source or modification is located in an area 
designated as nonattainment pursuant to section 107 of the Act.
    (c)-(e) [Reserved]
    (f) Actuals PALs. The plan shall provide for PALs according to the 
provisions in paragraphs (f)(1) through (15) of this section.
    (1) Applicability. (i) The reviewing authority may approve the use 
of an actuals PAL for any existing major stationary source (except as 
provided in paragraph (f)(1)(ii) of this section) if the PAL meets the 
requirements in paragraphs (f)(1) through (15) of this section. The term 
``PAL'' shall mean ``actuals PAL'' throughout paragraph (f) of this 
section.
    (ii) The reviewing authority shall not allow an actuals PAL for VOC 
or NOX for any major stationary source located in an extreme 
ozone nonattainment area.
    (iii) Any physical change in or change in the method of operation of 
a major stationary source that maintains its total source-wide emissions 
below the PAL level, meets the requirements in paragraphs (f)(1) through 
(15) of this section, and complies with the PAL permit:
    (A) Is not a major modification for the PAL pollutant;
    (B) Does not have to be approved through the plan's nonattainment 
major NSR program; and
    (C) Is not subject to the provisions in paragraph (a)(5)(ii) of this 
section (restrictions on relaxing enforceable emission limitations that 
the major stationary source used to avoid applicability of the 
nonattainment major NSR program).
    (iv) Except as provided under paragraph (f)(1)(iii)(C) of this 
section, a major stationary source shall continue to comply with all 
applicable Federal or State requirements, emission limitations, and work 
practice requirements that were established prior to the effective date 
of the PAL.
    (2) Definitions. The plan shall use the definitions in paragraphs 
(f)(2)(i) through (xi) of this section for the purpose of developing and 
implementing regulations that authorize the use of actuals PALs 
consistent with paragraphs (f)(1) through (15) of this section. When a 
term is not defined in these paragraphs, it shall have the meaning given 
in paragraph (a)(1) of this section or in the Act.
    (i) Actuals PAL for a major stationary source means a PAL based on 
the baseline actual emissions (as defined in paragraph (a)(1)(xxxv) of 
this section) of all emissions units (as defined in paragraph 
(a)(1)(vii) of this section) at the source, that emit or have the 
potential to emit the PAL pollutant.
    (ii) Allowable emissions means ``allowable emissions'' as defined in 
paragraph (a)(1)(xi) of this section, except as this definition is 
modified according to paragraphs (f)(2)(ii)(A) through (B) of this 
section.

[[Page 250]]

    (A) The allowable emissions for any emissions unit shall be 
calculated considering any emission limitations that are enforceable as 
a practical matter on the emissions unit's potential to emit.
    (B) An emissions unit's potential to emit shall be determined using 
the definition in paragraph (a)(1)(iii) of this section, except that the 
words ``or enforceable as a practical matter'' should be added after 
``federally enforceable.''
    (iii) Small emissions unit means an emissions unit that emits or has 
the potential to emit the PAL pollutant in an amount less than the 
significant level for that PAL pollutant, as defined in paragraph 
(a)(1)(x) of this section or in the Act, whichever is lower.
    (iv) Major emissions unit means:
    (A) Any emissions unit that emits or has the potential to emit 100 
tons per year or more of the PAL pollutant in an attainment area; or
    (B) Any emissions unit that emits or has the potential to emit the 
PAL pollutant in an amount that is equal to or greater than the major 
source threshold for the PAL pollutant as defined by the Act for 
nonattainment areas. For example, in accordance with the definition of 
major stationary source in section 182(c) of the Act, an emissions unit 
would be a major emissions unit for VOC if the emissions unit is located 
in a serious ozone nonattainment area and it emits or has the potential 
to emit 50 or more tons of VOC per year.
    (v) Plantwide applicability limitation (PAL) means an emission 
limitation expressed in tons per year, for a pollutant at a major 
stationary source, that is enforceable as a practical matter and 
established source-wide in accordance with paragraphs (f)(1) through 
(f)(15) of this section.
    (vi) PAL effective date generally means the date of issuance of the 
PAL permit. However, the PAL effective date for an increased PAL is the 
date any emissions unit which is part of the PAL major modification 
becomes operational and begins to emit the PAL pollutant.
    (vii) PAL effective period means the period beginning with the PAL 
effective date and ending 10 years later.
    (viii) PAL major modification means, notwithstanding paragraphs 
(a)(1)(v) and (vi) of this section (the definitions for major 
modification and net emissions increase), any physical change in or 
change in the method of operation of the PAL source that causes it to 
emit the PAL pollutant at a level equal to or greater than the PAL.
    (ix) PAL permit means the major NSR permit, the minor NSR permit, or 
the State operating permit under a program that is approved into the 
plan, or the title V permit issued by the reviewing authority that 
establishes a PAL for a major stationary source.
    (x) PAL pollutant means the pollutant for which a PAL is established 
at a major stationary source.
    (xi) Significant emissions unit means an emissions unit that emits 
or has the potential to emit a PAL pollutant in an amount that is equal 
to or greater than the significant level (as defined in paragraph 
(a)(1)(x) of this section or in the Act, whichever is lower) for that 
PAL pollutant, but less than the amount that would qualify the unit as a 
major emissions unit as defined in paragraph (f)(2)(iv) of this section.
    (3) Permit application requirements. As part of a permit application 
requesting a PAL, the owner or operator of a major stationary source 
shall submit the following information to the reviewing authority for 
approval:
    (i) A list of all emissions units at the source designated as small, 
significant or major based on their potential to emit. In addition, the 
owner or operator of the source shall indicate which, if any, Federal or 
State applicable requirements, emission limitations or work practices 
apply to each unit.
    (ii) Calculations of the baseline actual emissions (with supporting 
documentation). Baseline actual emissions are to include emissions 
associated not only with operation of the unit, but also emissions 
associated with startup, shutdown and malfunction.
    (iii) The calculation procedures that the major stationary source 
owner or operator proposes to use to convert the monitoring system data 
to monthly emissions and annual emissions based on a 12-month rolling 
total for each month as required by paragraph (f)(13)(i) of this 
section.

[[Page 251]]

    (4) General requirements for establishing PALs. (i) The plan allows 
the reviewing authority to establish a PAL at a major stationary source, 
provided that at a minimum, the requirements in paragraphs (f)(4)(i)(A) 
through (G) of this section are met.
    (A) The PAL shall impose an annual emission limitation in tons per 
year, that is enforceable as a practical matter, for the entire major 
stationary source. For each month during the PAL effective period after 
the first 12 months of establishing a PAL, the major stationary source 
owner or operator shall show that the sum of the monthly emissions from 
each emissions unit under the PAL for the previous 12 consecutive months 
is less than the PAL (a 12-month average, rolled monthly). For each 
month during the first 11 months from the PAL effective date, the major 
stationary source owner or operator shall show that the sum of the 
preceding monthly emissions from the PAL effective date for each 
emissions unit under the PAL is less than the PAL.
    (B) The PAL shall be established in a PAL permit that meets the 
public participation requirements in paragraph (f)(5) of this section.
    (C) The PAL permit shall contain all the requirements of paragraph 
(f)(7) of this section.
    (D) The PAL shall include fugitive emissions, to the extent 
quantifiable, from all emissions units that emit or have the potential 
to emit the PAL pollutant at the major stationary source.
    (E) Each PAL shall regulate emissions of only one pollutant.
    (F) Each PAL shall have a PAL effective period of 10 years.
    (G) The owner or operator of the major stationary source with a PAL 
shall comply with the monitoring, recordkeeping, and reporting 
requirements provided in paragraphs (f)(12) through (14) of this section 
for each emissions unit under the PAL through the PAL effective period.
    (ii) At no time (during or after the PAL effective period) are 
emissions reductions of a PAL pollutant, which occur during the PAL 
effective period, creditable as decreases for purposes of offsets under 
paragraph (a)(3)(ii) of this section unless the level of the PAL is 
reduced by the amount of such emissions reductions and such reductions 
would be creditable in the absence of the PAL.
    (5) Public participation requirement for PALs. PALs for existing 
major stationary sources shall be established, renewed, or increased 
through a procedure that is consistent with Sec. Sec. 51.160 and 51.161 
of this chapter. This includes the requirement that the reviewing 
authority provide the public with notice of the proposed approval of a 
PAL permit and at least a 30-day period for submittal of public comment. 
The reviewing authority must address all material comments before taking 
final action on the permit.
    (6) Setting the 10-year actuals PAL level. (i) Except as provided in 
paragraph (f)(6)(ii) of this section, the plan shall provide that the 
actuals PAL level for a major stationary source shall be established as 
the sum of the baseline actual emissions (as defined in paragraph 
(a)(1)(xxxv) of this section) of the PAL pollutant for each emissions 
unit at the source; plus an amount equal to the applicable significant 
level for the PAL pollutant under paragraph (a)(1)(x) of this section or 
under the Act, whichever is lower. When establishing the actuals PAL 
level, for a PAL pollutant, only one consecutive 24-month period must be 
used to determine the baseline actual emissions for all existing 
emissions units. However, a different consecutive 24-month period may be 
used for each different PAL pollutant. Emissions associated with units 
that were permanently shut down after this 24-month period must be 
subtracted from the PAL level. The reviewing authority shall specify a 
reduced PAL level(s) (in tons/yr) in the PAL permit to become effective 
on the future compliance date(s) of any applicable Federal or State 
regulatory requirement(s) that the reviewing authority is aware of prior 
to issuance of the PAL permit. For instance, if the source owner or 
operator will be required to reduce emissions from industrial boilers in 
half from baseline emissions of 60 ppm NOX to a new rule 
limit of 30 ppm, then the permit shall contain a future effective PAL 
level that is equal to the current

[[Page 252]]

PAL level reduced by half of the original baseline emissions of such 
unit(s).
    (ii) For newly constructed units (which do not include modifications 
to existing units) on which actual construction began after the 24-month 
period, in lieu of adding the baseline actual emissions as specified in 
paragraph (f)(6)(i) of this section, the emissions must be added to the 
PAL level in an amount equal to the potential to emit of the units.
    (7) Contents of the PAL permit. The plan shall require that the PAL 
permit contain, at a minimum, the information in paragraphs (f)(7)(i) 
through (x) of this section.
    (i) The PAL pollutant and the applicable source-wide emission 
limitation in tons per year.
    (ii) The PAL permit effective date and the expiration date of the 
PAL (PAL effective period).
    (iii) Specification in the PAL permit that if a major stationary 
source owner or operator applies to renew a PAL in accordance with 
paragraph (f)(10) of this section before the end of the PAL effective 
period, then the PAL shall not expire at the end of the PAL effective 
period. It shall remain in effect until a revised PAL permit is issued 
by the reviewing authority.
    (iv) A requirement that emission calculations for compliance 
purposes include emissions from startups, shutdowns and malfunctions.
    (v) A requirement that, once the PAL expires, the major stationary 
source is subject to the requirements of paragraph (f)(9) of this 
section.
    (vi) The calculation procedures that the major stationary source 
owner or operator shall use to convert the monitoring system data to 
monthly emissions and annual emissions based on a 12-month rolling total 
for each month as required by paragraph (f)(13)(i) of this section.
    (vii) A requirement that the major stationary source owner or 
operator monitor all emissions units in accordance with the provisions 
under paragraph (f)(12) of this section.
    (viii) A requirement to retain the records required under paragraph 
(f)(13) of this section on site. Such records may be retained in an 
electronic format.
    (ix) A requirement to submit the reports required under paragraph 
(f)(14) of this section by the required deadlines.
    (x) Any other requirements that the reviewing authority deems 
necessary to implement and enforce the PAL.
    (8) PAL effective period and reopening of the PAL permit. The plan 
shall require the information in paragraphs (f)(8)(i) and (ii) of this 
section.
    (i) PAL effective period. The reviewing authority shall specify a 
PAL effective period of 10 years.
    (ii) Reopening of the PAL permit. (A) During the PAL effective 
period, the plan shall require the reviewing authority to reopen the PAL 
permit to:
    (1) Correct typographical/calculation errors made in setting the PAL 
or reflect a more accurate determination of emissions used to establish 
the PAL.
    (2) Reduce the PAL if the owner or operator of the major stationary 
source creates creditable emissions reductions for use as offsets under 
paragraph (a)(3)(ii) of this section.
    (3) Revise the PAL to reflect an increase in the PAL as provided 
under paragraph (f)(11) of this section.
    (B) The plan shall provide the reviewing authority discretion to 
reopen the PAL permit for the following:
    (1) Reduce the PAL to reflect newly applicable Federal requirements 
(for example, NSPS) with compliance dates after the PAL effective date.
    (2) Reduce the PAL consistent with any other requirement, that is 
enforceable as a practical matter, and that the State may impose on the 
major stationary source under the plan.
    (3) Reduce the PAL if the reviewing authority determines that a 
reduction is necessary to avoid causing or contributing to a NAAQS or 
PSD increment violation, or to an adverse impact on an air quality 
related value that has been identified for a Federal Class I area by a 
Federal Land Manager and for which information is available to the 
general public.
    (C) Except for the permit reopening in paragraph (f)(8)(ii)(A)(1) of 
this section for the correction of typographical/calculation errors that 
do not increase the PAL level, all other reopenings shall be carried out 
in accordance with the public participation

[[Page 253]]

requirements of paragraph (f)(5) of this section.
    (9) Expiration of a PAL. Any PAL which is not renewed in accordance 
with the procedures in paragraph (f)(10) of this section shall expire at 
the end of the PAL effective period, and the requirements in paragraphs 
(f)(9)(i) through (v) of this section shall apply.
    (i) Each emissions unit (or each group of emissions units) that 
existed under the PAL shall comply with an allowable emission limitation 
under a revised permit established according to the procedures in 
paragraphs (f)(9)(i)(A) through (B) of this section.
    (A) Within the time frame specified for PAL renewals in paragraph 
(f)(10)(ii) of this section, the major stationary source shall submit a 
proposed allowable emission limitation for each emissions unit (or each 
group of emissions units, if such a distribution is more appropriate as 
decided by the reviewing authority) by distributing the PAL allowable 
emissions for the major stationary source among each of the emissions 
units that existed under the PAL. If the PAL had not yet been adjusted 
for an applicable requirement that became effective during the PAL 
effective period, as required under paragraph (f)(10)(v) of this 
section, such distribution shall be made as if the PAL had been 
adjusted.
    (B) The reviewing authority shall decide whether and how the PAL 
allowable emissions will be distributed and issue a revised permit 
incorporating allowable limits for each emissions unit, or each group of 
emissions units, as the reviewing authority determines is appropriate.
    (ii) Each emissions unit(s) shall comply with the allowable emission 
limitation on a 12-month rolling basis. The reviewing authority may 
approve the use of monitoring systems (source testing, emission factors, 
etc.) other than CEMS, CERMS, PEMS or CPMS to demonstrate compliance 
with the allowable emission limitation.
    (iii) Until the reviewing authority issues the revised permit 
incorporating allowable limits for each emissions unit, or each group of 
emissions units, as required under paragraph (f)(9)(i)(A) of this 
section, the source shall continue to comply with a source-wide, multi-
unit emissions cap equivalent to the level of the PAL emission 
limitation.
    (iv) Any physical change or change in the method of operation at the 
major stationary source will be subject to the nonattainment major NSR 
requirements if such change meets the definition of major modification 
in paragraph (a)(1)(v) of this section.
    (v) The major stationary source owner or operator shall continue to 
comply with any State or Federal applicable requirements (BACT, RACT, 
NSPS, etc.) that may have applied either during the PAL effective period 
or prior to the PAL effective period except for those emission 
limitations that had been established pursuant to paragraph (a)(5)(ii) 
of this section, but were eliminated by the PAL in accordance with the 
provisions in paragraph (f)(1)(iii)(C) of this section.
    (10) Renewal of a PAL. (i) The reviewing authority shall follow the 
procedures specified in paragraph (f)(5) of this section in approving 
any request to renew a PAL for a major stationary source, and shall 
provide both the proposed PAL level and a written rationale for the 
proposed PAL level to the public for review and comment. During such 
public review, any person may propose a PAL level for the source for 
consideration by the reviewing authority.
    (ii) Application deadline. The plan shall require that a major 
stationary source owner or operator shall submit a timely application to 
the reviewing authority to request renewal of a PAL. A timely 
application is one that is submitted at least 6 months prior to, but not 
earlier than 18 months from, the date of permit expiration. This 
deadline for application submittal is to ensure that the permit will not 
expire before the permit is renewed. If the owner or operator of a major 
stationary source submits a complete application to renew the PAL within 
this time period, then the PAL shall continue to be effective until the 
revised permit with the renewed PAL is issued.
    (iii) Application requirements. The application to renew a PAL 
permit shall contain the information required in paragraphs 
(f)(10)(iii)(A) through (D) of this section.

[[Page 254]]

    (A) The information required in paragraphs (f)(3)(i) through (iii) 
of this section.
    (B) A proposed PAL level.
    (C) The sum of the potential to emit of all emissions units under 
the PAL (with supporting documentation).
    (D) Any other information the owner or operator wishes the reviewing 
authority to consider in determining the appropriate level for renewing 
the PAL.
    (iv) PAL adjustment. In determining whether and how to adjust the 
PAL, the reviewing authority shall consider the options outlined in 
paragraphs (f)(10)(iv)(A) and (B) of this section. However, in no case 
may any such adjustment fail to comply with paragraph (f)(10)(iv)(C) of 
this section.
    (A) If the emissions level calculated in accordance with paragraph 
(f)(6) of this section is equal to or greater than 80 percent of the PAL 
level, the reviewing authority may renew the PAL at the same level 
without considering the factors set forth in paragraph (f)(10)(iv)(B) of 
this section; or
    (B) The reviewing authority may set the PAL at a level that it 
determines to be more representative of the source's baseline actual 
emissions, or that it determines to be appropriate considering air 
quality needs, advances in control technology, anticipated economic 
growth in the area, desire to reward or encourage the source's voluntary 
emissions reductions, or other factors as specifically identified by the 
reviewing authority in its written rationale.
    (C) Notwithstanding paragraphs (f)(10)(iv)(A) and (B) of this 
section,
    (1) If the potential to emit of the major stationary source is less 
than the PAL, the reviewing authority shall adjust the PAL to a level no 
greater than the potential to emit of the source; and
    (2) The reviewing authority shall not approve a renewed PAL level 
higher than the current PAL, unless the major stationary source has 
complied with the provisions of paragraph (f)(11) of this section 
(increasing a PAL).
    (v) If the compliance date for a State or Federal requirement that 
applies to the PAL source occurs during the PAL effective period, and if 
the reviewing authority has not already adjusted for such requirement, 
the PAL shall be adjusted at the time of PAL permit renewal or title V 
permit renewal, whichever occurs first.
    (11) Increasing a PAL during the PAL effective period. (i) The plan 
shall require that the reviewing authority may increase a PAL emission 
limitation only if the major stationary source complies with the 
provisions in paragraphs (f)(11)(i)(A) through (D) of this section.
    (A) The owner or operator of the major stationary source shall 
submit a complete application to request an increase in the PAL limit 
for a PAL major modification. Such application shall identify the 
emissions unit(s) contributing to the increase in emissions so as to 
cause the major stationary source's emissions to equal or exceed its 
PAL.
    (B) As part of this application, the major stationary source owner 
or operator shall demonstrate that the sum of the baseline actual 
emissions of the small emissions units, plus the sum of the baseline 
actual emissions of the significant and major emissions units assuming 
application of BACT equivalent controls, plus the sum of the allowable 
emissions of the new or modified emissions unit(s) exceeds the PAL. The 
level of control that would result from BACT equivalent controls on each 
significant or major emissions unit shall be determined by conducting a 
new BACT analysis at the time the application is submitted, unless the 
emissions unit is currently required to comply with a BACT or LAER 
requirement that was established within the preceding 10 years. In such 
a case, the assumed control level for that emissions unit shall be equal 
to the level of BACT or LAER with which that emissions unit must 
currently comply.
    (C) The owner or operator obtains a major NSR permit for all 
emissions unit(s) identified in paragraph (f)(11)(i)(A) of this section, 
regardless of the magnitude of the emissions increase resulting from 
them (that is, no significant levels apply). These emissions unit(s) 
shall comply with any emissions requirements resulting from the 
nonattainment major NSR program process (for example, LAER),

[[Page 255]]

even though they have also become subject to the PAL or continue to be 
subject to the PAL.
    (D) The PAL permit shall require that the increased PAL level shall 
be effective on the day any emissions unit that is part of the PAL major 
modification becomes operational and begins to emit the PAL pollutant.
    (ii) The reviewing authority shall calculate the new PAL as the sum 
of the allowable emissions for each modified or new emissions unit, plus 
the sum of the baseline actual emissions of the significant and major 
emissions units (assuming application of BACT equivalent controls as 
determined in accordance with paragraph (f)(11)(i)(B)), plus the sum of 
the baseline actual emissions of the small emissions units.
    (iii) The PAL permit shall be revised to reflect the increased PAL 
level pursuant to the public notice requirements of paragraph (f)(5) of 
this section.
    (12) Monitoring requirements for PALs--(i) General requirements. (A) 
Each PAL permit must contain enforceable requirements for the monitoring 
system that accurately determines plantwide emissions of the PAL 
pollutant in terms of mass per unit of time. Any monitoring system 
authorized for use in the PAL permit must be based on sound science and 
meet generally acceptable scientific procedures for data quality and 
manipulation. Additionally, the information generated by such system 
must meet minimum legal requirements for admissibility in a judicial 
proceeding to enforce the PAL permit.
    (B) The PAL monitoring system must employ one or more of the four 
general monitoring approaches meeting the minimum requirements set forth 
in paragraphs (f)(12)(ii)(A) through (D) of this section and must be 
approved by the reviewing authority.
    (C) Notwithstanding paragraph (f)(12)(i)(B) of this section, you may 
also employ an alternative monitoring approach that meets paragraph 
(f)(12)(i)(A) of this section if approved by the reviewing authority.
    (D) Failure to use a monitoring system that meets the requirements 
of this section renders the PAL invalid.
    (ii) Minimum Performance Requirements for Approved Monitoring 
Approaches. The following are acceptable general monitoring approaches 
when conducted in accordance with the minimum requirements in paragraphs 
(f)(12)(iii) through (ix) of this section:
    (A) Mass balance calculations for activities using coatings or 
solvents;
    (B) CEMS;
    (C) CPMS or PEMS; and
    (D) Emission Factors.
    (iii) Mass Balance Calculations. An owner or operator using mass 
balance calculations to monitor PAL pollutant emissions from activities 
using coating or solvents shall meet the following requirements:
    (A) Provide a demonstrated means of validating the published content 
of the PAL pollutant that is contained in or created by all materials 
used in or at the emissions unit;
    (B) Assume that the emissions unit emits all of the PAL pollutant 
that is contained in or created by any raw material or fuel used in or 
at the emissions unit, if it cannot otherwise be accounted for in the 
process; and
    (C) Where the vendor of a material or fuel, which is used in or at 
the emissions unit, publishes a range of pollutant content from such 
material, the owner or operator must use the highest value of the range 
to calculate the PAL pollutant emissions unless the reviewing authority 
determines there is site-specific data or a site-specific monitoring 
program to support another content within the range.
    (iv) CEMS. An owner or operator using CEMS to monitor PAL pollutant 
emissions shall meet the following requirements:
    (A) CEMS must comply with applicable Performance Specifications 
found in 40 CFR part 60, appendix B; and
    (B) CEMS must sample, analyze and record data at least every 15 
minutes while the emissions unit is operating.
    (v) CPMS or PEMS. An owner or operator using CPMS or PEMS to monitor 
PAL pollutant emissions shall meet the following requirements:
    (A) The CPMS or the PEMS must be based on current site-specific data 
demonstrating a correlation between the monitored parameter(s) and the 
PAL pollutant emissions across the

[[Page 256]]

range of operation of the emissions unit; and
    (B) Each CPMS or PEMS must sample, analyze, and record data at least 
every 15 minutes, or at another less frequent interval approved by the 
reviewing authority, while the emissions unit is operating.
    (vi) Emission factors. An owner or operator using emission factors 
to monitor PAL pollutant emissions shall meet the following 
requirements:
    (A) All emission factors shall be adjusted, if appropriate, to 
account for the degree of uncertainty or limitations in the factors' 
development;
    (B) The emissions unit shall operate within the designated range of 
use for the emission factor, if applicable; and
    (C) If technically practicable, the owner or operator of a 
significant emissions unit that relies on an emission factor to 
calculate PAL pollutant emissions shall conduct validation testing to 
determine a site-specific emission factor within 6 months of PAL permit 
issuance, unless the reviewing authority determines that testing is not 
required.
    (vii) A source owner or operator must record and report maximum 
potential emissions without considering enforceable emission limitations 
or operational restrictions for an emissions unit during any period of 
time that there is no monitoring data, unless another method for 
determining emissions during such periods is specified in the PAL 
permit.
    (viii) Notwithstanding the requirements in paragraphs (f)(12)(iii) 
through (vii) of this section, where an owner or operator of an 
emissions unit cannot demonstrate a correlation between the monitored 
parameter(s) and the PAL pollutant emissions rate at all operating 
points of the emissions unit, the reviewing authority shall, at the time 
of permit issuance:
    (A) Establish default value(s) for determining compliance with the 
PAL based on the highest potential emissions reasonably estimated at 
such operating point(s); or
    (B) Determine that operation of the emissions unit during operating 
conditions when there is no correlation between monitored parameter(s) 
and the PAL pollutant emissions is a violation of the PAL.
    (ix) Re-validation. All data used to establish the PAL pollutant 
must be re-validated through performance testing or other scientifically 
valid means approved by the reviewing authority. Such testing must occur 
at least once every 5 years after issuance of the PAL.
    (13) Recordkeeping requirements. (i) The PAL permit shall require an 
owner or operator to retain a copy of all records necessary to determine 
compliance with any requirement of paragraph (f) of this section and of 
the PAL, including a determination of each emissions unit's 12-month 
rolling total emissions, for 5 years from the date of such record.
    (ii) The PAL permit shall require an owner or operator to retain a 
copy of the following records for the duration of the PAL effective 
period plus 5 years:
    (A) A copy of the PAL permit application and any applications for 
revisions to the PAL; and
    (B) Each annual certification of compliance pursuant to title V and 
the data relied on in certifying the compliance.
    (14) Reporting and notification requirements. The owner or operator 
shall submit semi-annual monitoring reports and prompt deviation reports 
to the reviewing authority in accordance with the applicable title V 
operating permit program. The reports shall meet the requirements in 
paragraphs (f)(14)(i) through (iii).
    (i) Semi-Annual Report. The semi-annual report shall be submitted to 
the reviewing authority within 30 days of the end of each reporting 
period. This report shall contain the information required in paragraphs 
(f)(14)(i)(A) through (G) of this section.
    (A) The identification of owner and operator and the permit number.
    (B) Total annual emissions (tons/year) based on a 12-month rolling 
total for each month in the reporting period recorded pursuant to 
paragraph (f)(13)(i) of this section.

[[Page 257]]

    (C) All data relied upon, including, but not limited to, any Quality 
Assurance or Quality Control data, in calculating the monthly and annual 
PAL pollutant emissions.
    (D) A list of any emissions units modified or added to the major 
stationary source during the preceding 6-month period.
    (E) The number, duration, and cause of any deviations or monitoring 
malfunctions (other than the time associated with zero and span 
calibration checks), and any corrective action taken.
    (F) A notification of a shutdown of any monitoring system, whether 
the shutdown was permanent or temporary, the reason for the shutdown, 
the anticipated date that the monitoring system will be fully 
operational or replaced with another monitoring system, and whether the 
emissions unit monitored by the monitoring system continued to operate, 
and the calculation of the emissions of the pollutant or the number 
determined by method included in the permit, as provided by paragraph 
(f)(12)(vii) of this section.
    (G) A signed statement by the responsible official (as defined by 
the applicable title V operating permit program) certifying the truth, 
accuracy, and completeness of the information provided in the report.
    (ii) Deviation report. The major stationary source owner or operator 
shall promptly submit reports of any deviations or exceedance of the PAL 
requirements, including periods where no monitoring is available. A 
report submitted pursuant to Sec. 70.6(a)(3)(iii)(B) of this chapter 
shall satisfy this reporting requirement. The deviation reports shall be 
submitted within the time limits prescribed by the applicable program 
implementing Sec. 70.6(a)(3)(iii)(B) of this chapter. The reports shall 
contain the following information:
    (A) The identification of owner and operator and the permit number;
    (B) The PAL requirement that experienced the deviation or that was 
exceeded;
    (C) Emissions resulting from the deviation or the exceedance; and
    (D) A signed statement by the responsible official (as defined by 
the applicable title V operating permit program) certifying the truth, 
accuracy, and completeness of the information provided in the report.
    (iii) Re-validation results. The owner or operator shall submit to 
the reviewing authority the results of any re-validation test or method 
within 3 months after completion of such test or method.
    (15) Transition requirements. (i) No reviewing authority may issue a 
PAL that does not comply with the requirements in paragraphs (f)(1) 
through (15) of this section after the Administrator has approved 
regulations incorporating these requirements into a plan.
    (ii) The reviewing authority may supersede any PAL which was 
established prior to the date of approval of the plan by the 
Administrator with a PAL that complies with the requirements of 
paragraphs (f)(1) through (15) of this section.
    (g) If any provision of this section, or the application of such 
provision to any person or circumstance, is held invalid, the remainder 
of this section, or the application of such provision to persons or 
circumstances other than those as to which it is held invalid, shall not 
be affected thereby.
    (h) Equipment replacement provision. Without regard to other 
considerations, routine maintenance, repair and replacement includes, 
but is not limited to, the replacement of any component of a process 
unit with an identical or functionally equivalent component(s), and 
maintenance and repair activities that are part of the replacement 
activity, provided that all of the requirements in paragraphs (h)(1) 
through (3) of this section are met.
    (1) Capital Cost threshold for Equipment Replacement. (i) For an 
electric utility steam generating unit, as defined in Sec. 
51.165(a)(1)(xx), the fixed capital cost of the replacement component(s) 
plus the cost of any associated maintenance and repair activities that 
are part of the replacement shall not exceed 20 percent of the 
replacement value of the process unit, at the time the equipment is 
replaced. For a process unit that is not an electric utility steam 
generating unit the fixed capital cost of the replacement component(s) 
plus the cost of any associated maintenance

[[Page 258]]

and repair activities that are part of the replacement shall not exceed 
20 percent of the replacement value of the process unit, at the time the 
equipment is replaced.
    (ii) In determining the replacement value of the process unit; and, 
except as otherwise allowed under paragraph (h)(1)(iii) of this section, 
the owner or operator shall determine the replacement value of the 
process unit on an estimate of the fixed capital cost of constructing a 
new process unit, or on the current appraised value of the process unit.
    (iii) As an alternative to paragraph (h)(1)(ii) of this section for 
determining the replacement value of a process unit, an owner or 
operator may choose to use insurance value (where the insurance value 
covers only complete replacement), investment value adjusted for 
inflation, or another accounting procedure if such procedure is based on 
Generally Accepted Accounting Principles, provided that the owner or 
operator sends a notice to the reviewing authority. The first time that 
an owner or operator submits such a notice for a particular process 
unit, the notice may be submitted at any time, but any subsequent notice 
for that process unit may be submitted only at the beginning of the 
process unit's fiscal year. Unless the owner or operator submits a 
notice to the reviewing authority, then paragraph (h)(1)(ii) of this 
section will be used to establish the replacement value of the process 
unit. Once the owner or operator submits a notice to use an alternative 
accounting procedure, the owner or operator must continue to use that 
procedure for the entire fiscal year for that process unit. In 
subsequent fiscal years, the owner or operator must continue to use this 
selected procedure unless and until the owner or operator sends another 
notice to the reviewing authority selecting another procedure consistent 
with this paragraph or paragraph (h)(1)(ii) of this section at the 
beginning of such fiscal year.
    (2) Basic design parameters. The replacement does not change the 
basic design parameter(s) of the process unit to which the activity 
pertains.

    Note to paragraph (h): By a court order on December 24, 2003, this 
paragraph (h) is stayed indefinitely. The stayed provisions will become 
effective immediately if the court terminates the stay. At that time, 
EPA will publish a document in the Federal Register advising the public 
of the termination of the stay.

    (i) Except as provided in paragraph (h)(2)(iii) of this section, for 
a process unit at a steam electric generating facility, the owner or 
operator may select as its basic design parameters either maximum hourly 
heat input and maximum hourly fuel consumption rate or maximum hourly 
electric output rate and maximum steam flow rate. When establishing fuel 
consumption specifications in terms of weight or volume, the minimum 
fuel quality based on British Thermal Units content shall be used for 
determining the basic design parameter(s) for a coal-fired electric 
utility steam generating unit.
    (ii) Except as provided in paragraph (h)(2)(iii) of this section, 
the basic design parameter(s) for any process unit that is not at a 
steam electric generating facility are maximum rate of fuel or heat 
input, maximum rate of material input, or maximum rate of product 
output. Combustion process units will typically use maximum rate of fuel 
input. For sources having multiple end products and raw materials, the 
owner or operator should consider the primary product or primary raw 
material when selecting a basic design parameter.
    (iii) If the owner or operator believes the basic design 
parameter(s) in paragraphs (h)(2)(i) and (ii) of this section is not 
appropriate for a specific industry or type of process unit, the owner 
or operator may propose to the reviewing authority an alternative basic 
design parameter(s) for the source's process unit(s). If the reviewing 
authority approves of the use of an alternative basic design 
parameter(s), the reviewing authority shall issue a permit that is 
legally enforceable that records such basic design parameter(s) and 
requires the owner or operator to comply with such parameter(s).
    (iv) The owner or operator shall use credible information, such as 
results of historic maximum capability tests, design information from 
the manufacturer, or engineering calculations, in

[[Page 259]]

establishing the magnitude of the basic design parameter(s) specified in 
paragraphs (h)(2)(i) and (ii) of this section.
    (v) If design information is not available for a process unit, then 
the owner or operator shall determine the process unit's basic design 
parameter(s) using the maximum value achieved by the process unit in the 
five-year period immediately preceding the planned activity.
    (vi) Efficiency of a process unit is not a basic design parameter.
    (3) The replacement activity shall not cause the process unit to 
exceed any emission limitation, or operational limitation that has the 
effect of constraining emissions, that applies to the process unit and 
that is legally enforceable.
    (i) Public participation requirements. The reviewing authority shall 
notify the public of a draft permit by a method described in either 
paragraph (i)(1) or (2) of this section. The selected method, known as 
the ``consistent noticing method,'' shall comply with the public 
participation procedural requirements of Sec. 51.161 of this chapter 
and be used for all permits issued under this section and may, when 
appropriate, be supplemented by other noticing methods on individual 
permits.
    (1) Post the information in paragraphs (i)(1)(i) through (iii) of 
this section, for the duration of the public comment period, on a public 
Web site identified by the reviewing authority.
    (i) A notice of availability of the draft permit for public comment;
    (ii) The draft permit; and
    (iii) Information on how to access the administrative record for the 
draft permit.
    (2) Publish a notice of availability of the draft permit for public 
comment in a newspaper of general circulation in the area where the 
source is located. The notice shall include information on how to access 
the draft permit and the administrative record for the draft permit.

[51 FR 40669, Nov. 7, 1986]

    Editorial Note: For Federal Register citations affecting Sec. 
51.165, see the List of CFR Sections Affected, which appears in the 
Finding Aids section of the printed volume and at www.govinfo.gov.

    Effective Date Note: At 76 FR 17552, Mar. 30, 2011, Sec. 51.165, 
paragraphs (a)(1)(v)(G) and (v)(1)(vi)(C)(3) are stayed indefinitely.



Sec. 51.166  Prevention of significant deterioration of air quality.

    (a)(1) Plan requirements. In accordance with the policy of section 
101(b)(1) of the Act and the purposes of section 160 of the Act, each 
applicable State Implementation Plan and each applicable Tribal 
Implementation Plan shall contain emission limitations and such other 
measures as may be necessary to prevent significant deterioration of air 
quality.
    (2) Plan revisions. If a State Implementation Plan revision would 
result in increased air quality deterioration over any baseline 
concentration, the plan revision shall include a demonstration that it 
will not cause or contribute to a violation of the applicable 
increment(s). If a plan revision proposing less restrictive requirements 
was submitted after August 7, 1977 but on or before any applicable 
baseline date and was pending action by the Administrator on that date, 
no such demonstration is necessary with respect to the area for which a 
baseline date would be established before final action is taken on the 
plan revision. Instead, the assessment described in paragraph (a)(4) of 
this section, shall review the expected impact to the applicable 
increment(s).
    (3) Required plan revision. If the State or the Administrator 
determines that a plan is substantially inadequate to prevent 
significant deterioration or that an applicable increment is being 
violated, the plan shall be revised to correct the inadequacy or the 
violation. The plan shall be revised within 60 days of such a finding by 
a State or within 60 days following notification by the Administrator, 
or by such later date as prescribed by the Administrator after 
consultation with the State.
    (4) Plan assessment. The State shall review the adequacy of a plan 
on a periodic basis and within 60 days of such time as information 
becomes available that an applicable increment is being violated.
    (5) Public participation. Any State action taken under this 
paragraph shall be subject to the opportunity for public hearing in 
accordance with procedures

[[Page 260]]

equivalent to those established in Sec. 51.102.
    (6) Amendments. (i) Any State required to revise its implementation 
plan by reason of an amendment to this section, with the exception of 
amendments to add new maximum allowable increases or other measures 
pursuant to section 166(a) of the Act, shall adopt and submit such plan 
revision to the Administrator for approval no later than 3 years after 
such amendment is published in the Federal Register. With regard to a 
revision to an implementation plan by reason of an amendment to 
paragraph (c) of this section to add maximum allowable increases or 
other measures, the State shall submit such plan revision to the 
Administrator for approval within 21 months after such amendment is 
published in the Federal Register.
    (ii) Any revision to an implementation plan that would amend the 
provisions for the prevention of significant air quality deterioration 
in the plan shall specify when and as to what sources and modifications 
the revision is to take effect.
    (iii) Any revision to an implementation plan that an amendment to 
this section required shall take effect no later than the date of its 
approval and may operate prospectively.
    (7) Applicability. Each plan shall contain procedures that 
incorporate the requirements in paragraphs (a)(7)(i) through (vi) of 
this section.
    (i) The requirements of this section apply to the construction of 
any new major stationary source (as defined in paragraph (b)(1) of this 
section) or any project at an existing major stationary source in an 
area designated as attainment or unclassifiable under sections 
107(d)(1)(A)(ii) or (iii) of the Act.
    (ii) The requirements of paragraphs (j) through (r) of this section 
apply to the construction of any new major stationary source or the 
major modification of any existing major stationary source, except as 
this section otherwise provides.
    (iii) No new major stationary source or major modification to which 
the requirements of paragraphs (j) through (r)(5) of this section apply 
shall begin actual construction without a permit that states that the 
major stationary source or major modification will meet those 
requirements.
    (iv) Each plan shall use the specific provisions of paragraphs 
(a)(7)(iv)(a) through (f) of this section. Deviations from these 
provisions will be approved only if the State specifically demonstrates 
that the submitted provisions are more stringent than or at least as 
stringent in all respects as the corresponding provisions in paragraphs 
(a)(7)(iv)(a) through (f) of this section.
    (a) Except as otherwise provided in paragraphs (a)(7)(v) and (vi) of 
this section, and consistent with the definition of major modification 
contained in paragraph (b)(2) of this section, a project is a major 
modification for a regulated NSR pollutant if it causes two types of 
emissions increases--a significant emissions increase (as defined in 
paragraph (b)(39) of this section), and a significant net emissions 
increase (as defined in paragraphs (b)(3) and (b)(23) of this section). 
The project is not a major modification if it does not cause a 
significant emissions increase. If the project causes a significant 
emissions increase, then the project is a major modification only if it 
also results in a significant net emissions increase.
    (b) The procedure for calculating (before beginning actual 
construction) whether a significant emissions increase (i.e., the first 
step of the process) will occur depends upon the type of emissions units 
being modified, according to paragraphs (a)(7)(iv)(c) through (f) of 
this section. The procedure for calculating (before beginning actual 
construction) whether a significant net emissions increase will occur at 
the major stationary source (i.e., the second step of the process) is 
contained in the definition in paragraph (b)(3) of this section. 
Regardless of any such preconstruction projections, a major modification 
results if the project causes a significant emissions increase and a 
significant net emissions increase.
    (c) Actual-to-projected-actual applicability test for projects that 
only involve existing emissions units. A significant emissions increase 
of a regulated NSR pollutant is projected to occur if the sum of the 
difference between the projected actual emissions (as defined in

[[Page 261]]

paragraph (b)(40) of this section) and the baseline actual emissions (as 
defined in paragraphs (b)(47)(i) and (ii) of this section) for each 
existing emissions unit, equals or exceeds the significant amount for 
that pollutant (as defined in paragraph (b)(23) of this section).
    (d) Actual-to-potential test for projects that only involve 
construction of a new emissions unit(s). A significant emissions 
increase of a regulated NSR pollutant is projected to occur if the sum 
of the difference between the potential to emit (as defined in paragraph 
(b)(4) of this section) from each new emissions unit following 
completion of the project and the baseline actual emissions (as defined 
in paragraph (b)(47)(iii) of this section) of these units before the 
project equals or exceeds the significant amount for that pollutant (as 
defined in paragraph (b)(23) of this section).
    (e) [Reserved]
    (f) Hybrid test for projects that involve multiple types of 
emissions units. A significant emissions increase of a regulated NSR 
pollutant is projected to occur if the sum of the difference for all 
emissions units, using the method specified in paragraphs (a)(7)(iv)(c) 
through (d) of this section as applicable with respect to each emissions 
unit, equals or exceeds the significant amount for that pollutant (as 
defined in paragraph (b)(23) of this section).
    (g) The ``sum of the difference'' as used in paragraphs (c), (d) and 
(f) of this section shall include both increases and decreases in 
emissions calculated in accordance with those paragraphs.
    (v) The plan shall require that for any major stationary source for 
a PAL for a regulated NSR pollutant, the major stationary source shall 
comply with requirements under paragraph (w) of this section.
    (b) Definitions. All State plans shall use the following definitions 
for the purposes of this section. Deviations from the following wording 
will be approved only if the State specifically demonstrates that the 
submitted definition is more stringent, or at least as stringent, in all 
respects as the corresponding definitions below:
    (1)(i) Major stationary source means:
    (a) Any of the following stationary sources of air pollutants which 
emits, or has the potential to emit, 100 tons per year or more of any 
regulated NSR pollutant: Fossil fuel-fired steam electric plants of more 
than 250 million British thermal units per hour heat input, coal 
cleaning plants (with thermal dryers), kraft pulp mills, portland cement 
plants, primary zinc smelters, iron and steel mill plants, primary 
aluminum ore reduction plants (with thermal dryers), primary copper 
smelters, municipal incinerators capable of charging more than 250 tons 
of refuse per day, hydrofluoric, sulfuric, and nitric acid plants, 
petroleum refineries, lime plants, phosphate rock processing plants, 
coke oven batteries, sulfur recovery plants, carbon black plants 
(furnace process), primary lead smelters, fuel conversion plants, 
sintering plants, secondary metal production plants, chemical process 
plants (which does not include ethanol production facilities that 
produce ethanol by natural fermentation included in NAICS codes 325193 
or 312140), fossil-fuel boilers (or combinations thereof) totaling more 
than 250 million British thermal units per hour heat input, petroleum 
storage and transfer units with a total storage capacity exceeding 
300,000 barrels, taconite ore processing plants, glass fiber processing 
plants, and charcoal production plants;
    (b) Notwithstanding the stationary source size specified in 
paragraph (b)(1)(i)(a) of this section, any stationary source which 
emits, or has the potential to emit, 250 tons per year or more of a 
regulated NSR pollutant; or
    (c) Any physical change that would occur at a stationary source not 
otherwise qualifying under paragraph (b)(1) of this section, as a major 
stationary source if the change would constitute a major stationary 
source by itself.
    (ii) A major source that is major for volatile organic compounds or 
NOX shall be considered major for ozone.
    (iii) The fugitive emissions of a stationary source shall not be 
included in determining for any of the purposes of this section whether 
it is a major stationary source, unless the source belongs to one of the 
following categories of stationary sources:

[[Page 262]]

    (a) Coal cleaning plants (with thermal dryers);
    (b) Kraft pulp mills;
    (c) Portland cement plants;
    (d) Primary zinc smelters;
    (e) Iron and steel mills;
    (f) Primary aluminum ore reduction plants;
    (g) Primary copper smelters;
    (h) Municipal incinerators capable of charging more than 250 tons of 
refuse per day;
    (i) Hydrofluoric, sulfuric, or nitric acid plants;
    (j) Petroleum refineries;
    (k) Lime plants;
    (l) Phosphate rock processing plants;
    (m) Coke oven batteries;
    (n) Sulfur recovery plants;
    (o) Carbon black plants (furnace process);
    (p) Primary lead smelters;
    (q) Fuel conversion plants;
    (r) Sintering plants;
    (s) Secondary metal production plants;
    (t) Chemical process plants--The term chemical processing plant 
shall not include ethanol production facilities that produce ethanol by 
natural fermentation included in NAICS codes 325193 or 312140;
    (u) Fossil-fuel boilers (or combination thereof) totaling more than 
250 million British thermal units per hour heat input;
    (v) Petroleum storage and transfer units with a total storage 
capacity exceeding 300,000 barrels;
    (w) Taconite ore processing plants;
    (x) Glass fiber processing plants;
    (y) Charcoal production plants;
    (z) Fossil fuel-fired steam electric plants of more that 250 million 
British thermal units per hour heat input;
    (aa) Any other stationary source category which, as of August 7, 
1980, is being regulated under section 111 or 112 of the Act.
    (2)(i) Major modification means any physical change in or change in 
the method of operation of a major stationary source that would result 
in: a significant emissions increase (as defined in paragraph (b)(39) of 
this section) of a regulated NSR pollutant (as defined in paragraph 
(b)(49) of this section); and a significant net emissions increase of 
that pollutant from the major stationary source.
    (ii) Any significant emissions increase (as defined at paragraph 
(b)(39) of this section) from any emissions units or net emissions 
increase (as defined in paragraph (b)(3) of this section) at a major 
stationary source that is significant for volatile organic compounds or 
NOX shall be considered significant for ozone.
    (iii) A physical change or change in the method of operation shall 
not include:
    (a) Routine maintenance, repair and replacement. Routine 
maintenance, repair and replacement shall include, but not be limited 
to, any activity(s) that meets the requirements of the equipment 
replacement provisions contained in paragraph (y) of this section;

    Note to paragraph (b)(2)(iii)(a): On December 24, 2003, the second 
sentence of this paragraph (b)(2)(iii)(a) is stayed indefinitely by 
court order. The stayed provisions will become effective immediately if 
the court terminates the stay. At that time, EPA will publish a document 
in the Federal Register advising the public of the termination of the 
stay.

    (b) Use of an alternative fuel or raw material by reason of any 
order under section 2 (a) and (b) of the Energy Supply and Environmental 
Coordination Act of 1974 (or any superseding legislation) or by reason 
of a natural gas curtailment plan pursuant to the Federal Power Act;
    (c) Use of an alternative fuel by reason of an order or rule under 
section 125 of the Act;
    (d) Use of an alternative fuel at a steam generating unit to the 
extent that the fuel is generated from municipal solid waste;
    (e) Use of an alternative fuel or raw material by a stationary 
source which:
    (1) The source was capable of accommodating before January 6, 1975, 
unless such change would be prohibited under any federally enforceable 
permit condition which was established after January 6, 1975 pursuant to 
40 CFR 52.21 or under regulations approved pursuant to 40 CFR subpart I 
or Sec. 51.166; or
    (2) The source is approved to use under any permit issued under 40 
CFR 52.21 or under regulations approved pursuant to 40 CFR 51.166;

[[Page 263]]

    (f) An increase in the hours of operation or in the production rate, 
unless such change would be prohibited under any federally enforceable 
permit condition which was established after January 6, 1975, pursuant 
to 40 CFR 52.21 or under regulations approved pursuant to 40 CFR subpart 
I or Sec. 51.166.
    (g) Any change in ownership at a stationary source.
    (h) [Reserved]
    (i) The installation, operation, cessation, or removal of a 
temporary clean coal technology demonstration project, provided that the 
project complies with:
    (1) The State implementation plan for the State in which the project 
is located; and
    (2) Other requirements necessary to attain and maintain the national 
ambient air quality standards during the project and after it is 
terminated.
    (j) The installation or operation of a permanent clean coal 
technology demonstration project that constitutes repowering, provided 
that the project does not result in an increase in the potential to emit 
of any regulated pollutant emitted by the unit. This exemption shall 
apply on a pollutant-by-pollutant basis.
    (k) The reactivation of a very clean coal-fired electric utility 
steam generating unit.
    (iv) This definition shall not apply with respect to a particular 
regulated NSR pollutant when the major stationary source is complying 
with the requirements under paragraph (w) of this section for a PAL for 
that pollutant. Instead, the definition at paragraph (w)(2)(viii) of 
this section shall apply.
    (v) Fugitive emissions shall not be included in determining for any 
of the purposes of this section whether a physical change in or change 
in the method of operation of a major stationary source is a major 
modification, unless the source belongs to one of the source categories 
listed in paragraph (b)(1)(iii) of this section.
    (3)(i) Net emissions increase means, with respect to any regulated 
NSR pollutant emitted by a major stationary source, the amount by which 
the sum of the following exceeds zero:
    (a) The increase in emissions from a particular physical change or 
change in the method of operation at a stationary source as calculated 
pursuant to paragraph (a)(7)(iv) of this section; and
    (b) Any other increases and decreases in actual emissions at the 
major stationary source that are contemporaneous with the particular 
change and are otherwise creditable. Baseline actual emissions for 
calculating increases and decreases under this paragraph (b)(3)(i)(b) 
shall be determined as provided in paragraph (b)(47), except that 
paragraphs (b)(47)(i)(c) and (b)(47)(ii)(d) of this section shall not 
apply.
    (ii) An increase or decrease in actual emissions is contemporaneous 
with the increase from the particular change only if it occurs within a 
reasonable period (to be specified by the State) before the date that 
the increase from the particular change occurs.
    (iii) An increase or decrease in actual emissions is creditable only 
if:
    (a) It occurs within a reasonable period (to be specified by the 
reviewing authority); and
    (b) The reviewing authority has not relied on it in issuing a permit 
for the source under regulations approved pursuant to this section, 
which permit is in effect when the increase in actual emissions from the 
particular change occurs; and
    (c) The increase or decrease in emissions did not occur at a Clean 
Unit, except as provided in paragraphs (t)(8) and (u)(10) of this 
section.
    (d) As it pertains to an increase or decrease in fugitive emissions 
(to the extent quantifiable), it occurs at an emissions unit that is 
part of one of the source categories listed in paragraph (b)(1)(iii) of 
this section or it occurs at an emission unit that is located at a major 
stationary source that belongs to one of the listed source categories. 
Fugitive emission increases or decreases are not included for those 
emissions units located at a facility whose primary activity is not 
represented by one of the source categories listed in paragraph 
(b)(1)(iii) of this section and that are not, by themselves, part of a 
listed source category.

[[Page 264]]

    (iv) An increase or decrease in actual emissions of sulfur dioxide, 
particulate matter, or nitrogen oxides that occurs before the applicable 
minor source baseline date is creditable only if it is required to be 
considered in calculating the amount of maximum allowable increases 
remaining available.
    (v) An increase in actual emissions is creditable only to the extent 
that the new level of actual emissions exceeds the old level.
    (vi) A decrease in actual emissions is creditable only to the extent 
that:
    (a) The old level of actual emissions or the old level of allowable 
emissions, whichever is lower, exceeds the new level of actual 
emissions;
    (b) It is enforceable as a practical matter at and after the time 
that actual construction on the particular change begins;
    (c) It has approximately the same qualitative significance for 
public health and welfare as that attributed to the increase from the 
particular change; and
    (vii) An increase that results from a physical change at a source 
occurs when the emissions unit on which construction occurred becomes 
operational and begins to emit a particular pollutant. Any replacement 
unit that requires shakedown becomes operational only after a reasonable 
shakedown period, not to exceed 180 days.
    (viii) Paragraph (b)(21)(ii) of this section shall not apply for 
determining creditable increases and decreases.
    (4) Potential to emit means the maximum capacity of a stationary 
source to emit a pollutant under its physical and operational design. 
Any physical or operational limitation on the capacity of the source to 
emit a pollutant, including air pollution control equipment and 
restrictions on hours of operation or on the type or amount of material 
combusted, stored, or processed, shall be treated as part of its design 
if the limitation or the effect it would have on emissions is federally 
enforceable. Secondary emissions do not count in determining the 
potential to emit of a stationary source.
    (5) Stationary source means any building, structure, facility, or 
installation which emits or may emit a regulated NSR pollutant.
    (6)(i) Building, structure, facility, or installation means all of 
the pollutant-emitting activities which belong to the same industrial 
grouping, are located on one or more contiguous or adjacent properties, 
and are under the control of the same person (or persons under common 
control) except the activities of any vessel. Pollutant-emitting 
activities shall be considered as part of the same industrial grouping 
if they belong to the same Major Group (i.e., which have the same two-
digit code) as described in the Standard Industrial Classification 
Manual, 1972, as amended by the 1977 Supplement (U.S. Government 
Printing Office stock numbers 4101-0066 and 003-005-00176-0, 
respectively).
    (ii) The plan may include the following provision: Notwithstanding 
the provisions of paragraph (b)(6)(i) of this section, building, 
structure, facility, or installation means, for onshore activities under 
SIC Major Group 13: Oil and Gas Extraction, all of the pollutant-
emitting activities included in Major Group 13 that are located on one 
or more contiguous or adjacent properties, and are under the control of 
the same person (or persons under common control). Pollutant emitting 
activities shall be considered adjacent if they are located on the same 
surface site; or if they are located on surface sites that are located 
within \1/4\ mile of one another (measured from the center of the 
equipment on the surface site) and they share equipment. Shared 
equipment includes, but is not limited to, produced fluids storage 
tanks, phase separators, natural gas dehydrators or emissions control 
devices. Surface site, as used in this paragraph (b)(6)(ii), has the 
same meaning as in 40 CFR 63.761.
    (7) Emissions unit means any part of a stationary source that emits 
or would have the potential to emit any regulated NSR pollutant and 
includes an electric utility steam generating unit as defined in 
paragraph (b)(30) of this section. For purposes of this section, there 
are two types of emissions units as described in paragraphs (b)(7)(i) 
and (ii) of this section.
    (i) A new emissions unit is any emissions unit that is (or will be) 
newly constructed and that has existed for less than 2 years from the 
date such emissions unit first operated.

[[Page 265]]

    (ii) An existing emissions unit is any emissions unit that does not 
meet the requirements in paragraph (b)(7)(i) of this section. A 
replacement unit, as defined in paragraph (b)(32) of this section, is an 
existing emissions unit.
    (8) Construction means any physical change or change in the method 
of operation (including fabrication, erection, installation, demolition, 
or modification of an emissions unit) that would result in a change in 
emissions.
    (9) Commence as applied to construction of a major stationary source 
or major modification means that the owner or operator has all necessary 
preconstruction approvals or permits and either has:
    (i) Begun, or caused to begin, a continuous program of actual on-
site construction of the source, to be completed within a reasonable 
time; or
    (ii) Entered into binding agreements or contractual obligations, 
which cannot be cancelled or modified without substantial loss to the 
owner or operator, to undertake a program of actual construction of the 
source to be completed within a reasonable time.
    (10) Necessary preconstruction approvals or permits means those 
permits or approvals required under Federal air quality control laws and 
regulations and those air quality control laws and regulations which are 
part of the applicable State Implementation Plan.
    (11) Begin actual construction means, in general, initiation of 
physical on-site construction activities on an emissions unit which are 
of a permanent nature. Such activities include, but are not limited to, 
installation of building supports and foundations, laying of underground 
pipework, and construction of permanent storage structures. With respect 
to a change in method of operation this term refers to those on-site 
activities, other than preparatory activities, which mark the initiation 
of the change.
    (12) Best available control technology means an emissions limitation 
(including a visible emissions standard) based on the maximum degree of 
reduction for each a regulated NSR pollutant which would be emitted from 
any proposed major stationary source or major modification which the 
reviewing authority, on a case-by-case basis, taking into account 
energy, environmental, and economic impacts and other costs, determines 
is achievable for such source or modification through application of 
production processes or available methods, systems, and techniques, 
including fuel cleaning or treatment or innovative fuel combination 
techniques for control of such pollutant. In no event shall application 
of best available control technology result in emissions of any 
pollutant which would exceed the emissions allowed by any applicable 
standard under 40 CFR parts 60 and 61. If the reviewing authority 
determines that technological or economic limitations on the application 
of measurement methodology to a particular emissions unit would make the 
imposition of an emissions standard infeasible, a design, equipment, 
work practice, operational standard or combination thereof, may be 
prescribed instead to satisfy the requirement for the application of 
best available control technology. Such standard shall, to the degree 
possible, set forth the emissions reduction achievable by implementation 
of such design, equipment, work practice or operation, and shall provide 
for compliance by means which achieve equivalent results.
    (13)(i) Baseline concentration means that ambient concentration 
level that exists in the baseline area at the time of the applicable 
minor source baseline date. A baseline concentration is determined for 
each pollutant for which a minor source baseline date is established and 
shall include:
    (a) The actual emissions, as defined in paragraph (b)(21) of this 
section, representative of sources in existence on the applicable minor 
source baseline date, except as provided in paragraph (b)(13)(ii) of 
this section;
    (b) The allowable emissions of major stationary sources that 
commenced construction before the major source baseline date, but were 
not in operation by the applicable minor source baseline date.
    (ii) The following will not be included in the baseline 
concentration and will affect the applicable maximum allowable 
increase(s):
    (a) Actual emissions, as defined in paragraph (b)(21) of this 
section, from any major stationary source on which

[[Page 266]]

construction commenced after the major source baseline date; and
    (b) Actual emissions increases and decreases, as defined in 
paragraph (b)(21) of this section, at any stationary source occurring 
after the minor source baseline date.
    (14)(i) Major source baseline date means:
    (a) In the case of PM10 and sulfur dioxide, January 6, 
1975;
    (b) In the case of nitrogen dioxide, February 8, 1988; and
    (c) In the case of PM2.5, October 20, 2010.
    (ii) Minor source baseline date means the earliest date after the 
trigger date on which a major stationary source or a major modification 
subject to 40 CFR 52.21 or to regulations approved pursuant to 40 CFR 
51.166 submits a complete application under the relevant regulations. 
The trigger date is:
    (a) In the case of PM10 and sulfur dioxide, August 7, 
1977;
    (b) In the case of nitrogen dioxide, February 8, 1988; and
    (c) In the case of PM2.5, October 20, 2011.
    (iii) The baseline date is established for each pollutant for which 
increments or other equivalent measures have been established if:
    (a) The area in which the proposed source or modification would 
construct is designated as attainment or unclassifiable under section 
107(d)(1)(A)(ii) or (iii) of the Act for the pollutant on the date of 
its complete application under 40 CFR 52.21 or under regulations 
approved pursuant to 40 CFR 51.166; and
    (b) In the case of a major stationary source, the pollutant would be 
emitted in significant amounts, or, in the case of a major modification, 
there would be a significant net emissions increase of the pollutant.
    (iv) Any minor source baseline date established originally for the 
TSP increments shall remain in effect and shall apply for purposes of 
determining the amount of available PM-10 increments, except that the 
reviewing authority may rescind any such minor source baseline date 
where it can be shown, to the satisfaction of the reviewing authority, 
that the emissions increase from the major stationary source, or the net 
emissions increase from the major modification, responsible for 
triggering that date did not result in a significant amount of PM-10 
emissions.
    (15)(i) Baseline area means any intrastate area (and every part 
thereof) designated as attainment or unclassifiable under section 
107(d)(1)(A)(ii) or (iii) of the Act in which the major source or major 
modification establishing the minor source baseline date would construct 
or would have an air quality impact for the pollutant for which the 
baseline date is established, as follows: Equal to or greater than 1 
[micro]g/m\3\ (annual average) for SO2, NO2, or 
PM10; or equal or greater than 0.3 [micro]g/m\3\ (annual 
average) for PM2.5.
    (ii) Area redesignations under section 107(d)(1)(A)(ii) or (iii) of 
the Act cannot intersect or be smaller than the area of impact of any 
major stationary source or major modification which:
    (a) Establishes a minor source baseline date; or
    (b) Is subject to 40 CFR 52.21 or under regulations approved 
pursuant to 40 CFR 51.166, and would be constructed in the same State as 
the State proposing the redesignation.
    (iii) Any baseline area established originally for the TSP 
increments shall remain in effect and shall apply for purposes of 
determining the amount of available PM-10 increments, except that such 
baseline area shall not remain in effect if the permit authority 
rescinds the corresponding minor source baseline date in accordance with 
paragraph (b)(14)(iv) of this section.
    (16) Allowable emissions means the emissions rate of a stationary 
source calculated using the maximum rated capacity of the source (unless 
the source is subject to federally enforceable limits which restrict the 
operating rate, or hours of operation, or both) and the most stringent 
of the following:
    (i) The applicable standards as set forth in 40 CFR parts 60 and 61;
    (ii) The applicable State Implementation Plan emissions limitation, 
including those with a future compliance date; or
    (iii) The emissions rate specified as a federally enforceable permit 
condition.

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    (17) Federally enforceable means all limitations and conditions 
which are enforceable by the Administrator, including those requirements 
developed pursuant to 40 CFR parts 60 and 61, requirements within any 
applicable State implementation plan, any permit requirements 
established pursuant to 40 CFR 52.21 or under regulations approved 
pursuant to 40 CFR part 51, subpart I, including operating permits 
issued under an EPA-approved program that is incorporated into the State 
implementation plan and expressly requires adherence to any permit 
issued under such program.
    (18) Secondary emissions means emissions which occur as a result of 
the construction or operation of a major stationary source or major 
modification, but do not come from the major stationary source or major 
modification itself. For the purposes of this section, secondary 
emissions must be specific, well defined, quantifiable, and impact the 
same general areas the stationary source modification which causes the 
secondary emissions. Secondary emissions include emissions from any 
offsite support facility which would not be constructed or increase its 
emissions except as a result of the construction or operation of the 
major stationary source or major modification. Secondary emissions do 
not include any emissions which come directly from a mobile source, such 
as emissions from the tailpipe of a motor vehicle, from a train, or from 
a vessel.
    (19) Innovative control technology means any system of air pollution 
control that has not been adequately demonstrated in practice, but would 
have a substantial likelihood of achieving greater continuous emissions 
reduction than any control system in current practice or of achieving at 
least comparable reductions at lower cost in terms of energy, economics, 
or nonair quality environmental impacts.
    (20) Fugitive emissions means those emissions which could not 
reasonably pass through a stack, chimney, vent, or other functionally 
equivalent opening.
    (21)(i) Actual emissions means the actual rate of emissions of a 
regulated NSR pollutant from an emissions unit, as determined in 
accordance with paragraphs (b)(21)(ii) through (iv) of this section, 
except that this definition shall not apply for calculating whether a 
significant emissions increase has occurred, or for establishing a PAL 
under paragraph (w) of this section. Instead, paragraphs (b)(40) and 
(b)(47) of this section shall apply for those purposes.
    (ii) In general, actual emissions as of a particular date shall 
equal the average rate, in tons per year, at which the unit actually 
emitted the pollutant during a consecutive 24-month period which 
precedes the particular date and which is representative of normal 
source operation. The reviewing authority shall allow the use of a 
different time period upon a determination that it is more 
representative of normal source operation. Actual emissions shall be 
calculated using the unit's actual operating hours, production rates, 
and types of materials processed, stored, or combusted during the 
selected time period.
    (iii) The reviewing authority may presume that source-specific 
allowable emissions for the unit are equivalent to the actual emissions 
of the unit.
    (iv) For any emissions unit that has not begun normal operations on 
the particular date, actual emissions shall equal the potential to emit 
of the unit on that date.
    (22) Complete means, in reference to an application for a permit, 
that the application contains all the information necessary for 
processing the application. Designating an application complete for 
purposes of permit processing does not preclude the reviewing authority 
from requesting or accepting any additional information.
    (23)(i) Significant means, in reference to a net emissions increase 
or the potential of a source to emit any of the following pollutants, a 
rate of emissions that would equal or exceed any of the following rates:

                      Pollutant and Emissions Rate

Carbon monoxide: 100 tons per year (tpy)
Nitrogen oxides: 40 tpy
Sulfur dioxide: 40 tpy
Particulate matter: 25 tpy of particulate matter emissions. 15 tpy of 
PM10 emissions
PM2.5: 10 tpy of direct PM2.5 emissions; 40 tpy of 
sulfur dioxide emissions; 40 tpy of nitrogen oxide emissions unless 
demonstrated not to be a PM2.5 precursor under paragraph 
(b)(49) of this section

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Ozone: 40 tpy of volatile organic compounds or nitrogen oxides
Lead: 0.6 tpy
Fluorides: 3 tpy
Sulfuric acid mist: 7 tpy
Hydrogen sulfide (H2S): 10 tpy
Total reduced sulfur (including H2S): 10 tpy
Reduced sulfur compounds (including H2S): 10 tpy
Municipal waste combustor organics (measured as total tetra-through 
octa-chlorinated dibenzo-p-dioxins and dibenzofurans): 3.2 x 10-
-6 megagrams per year (3.5 x 10-6 tons per year)
Municipal waste combustor metals (measured as particulate matter): 14 
megagrams per year (15 tons per year)
Municipal waste combustor acid gases (measured as sulfur dioxide and 
hydrogen chloride): 36 megagrams per year (40 tons per year)
Municipal solid waste landfill emissions (measured as nonmethane organic 
compounds): 45 megagrams per year (50 tons per year)

    (ii) Significant means, in reference to a net emissions increase or 
the potential of a source to emit a regulated NSR pollutant that 
paragraph (b)(23)(i) of this section, does not list, any emissions rate.
    (iii) Notwithstanding paragraph (b)(23)(i) of this section, 
significant means any emissions rate or any net emissions increase 
associated with a major stationary source or major modification, which 
would construct within 10 kilometers of a Class I area, and have an 
impact on such area equal to or greater than 1 [micro]g/m\3\ (24-hour 
average).
    (24) Federal Land Manager means, with respect to any lands in the 
United States, the Secretary of the department with authority over such 
lands.
    (25) High terrain means any area having an elevation 900 feet or 
more above the base of the stack of a source.
    (26) Low terrain means any area other than high terrain.
    (27) Indian Reservation means any federally recognized reservation 
established by Treaty, Agreement, Executive Order, or Act of Congress.
    (28) Indian Governing Body means the governing body of any tribe, 
band, or group of Indians subject to the jurisdiction of the United 
States and recognized by the United States as possessing power of self-
government.
    (29) Volatile organic compounds (VOC) is as defined in Sec. 
51.100(s) of this part.
    (30) Electric utility steam generating unit means any steam electric 
generating unit that is constructed for the purpose of supplying more 
than one-third of its potential electric output capacity and more than 
25 MW electrical output to any utility power distribution system for 
sale. Any steam supplied to a steam distribution system for the purpose 
of providing steam to a steam-electric generator that would produce 
electrical energy for sale is also considered in determining the 
electrical energy output capacity of the affected facility.
    (31) [Reserved]
    (32) Replacement unit means an emissions unit for which all the 
criteria listed in paragraphs (b)(32)(i) through (iv) of this section 
are met. No creditable emission reductions shall be generated from 
shutting down the existing emissions unit that is replaced.
    (i) The emissions unit is a reconstructed unit within the meaning of 
Sec. 60.15(b)(1) of this chapter, or the emissions unit completely 
takes the place of an existing emissions unit.
    (ii) The emissions unit is identical to or functionally equivalent 
to the replaced emissions unit.
    (iii) The replacement does not change the basic design parameter(s) 
(as discussed in paragraph (y)(2) of this section) of the process unit.
    (iv) The replaced emissions unit is permanently removed from the 
major stationary source, otherwise permanently disabled, or permanently 
barred from operation by a permit that is enforceable as a practical 
matter. If the replaced emissions unit is brought back into operation, 
it shall constitute a new emissions unit.
    (33) Clean coal technology means any technology, including 
technologies applied at the precombustion, combustion, or post 
combustion stage, at a new or existing facility which will achieve 
significant reductions in air emissions of sulfur dioxide or oxides of 
nitrogen associated with the utilization of coal in the generation of 
electricity, or process steam which was not in widespread use as of 
November 15, 1990.
    (34) Clean coal technology demonstration project means a project 
using funds

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appropriated under the heading ``Department of Energy--Clean Coal 
Technology'', up to a total amount of $2,500,000,000 for commercial 
demonstration of clean coal technology, or similar projects funded 
through appropriations for the Environmental Protection Agency. The 
Federal contribution for a qualifying project shall be at least 20 
percent of the total cost of the demonstration project.
    (35) Temporary clean coal technology demonstration project means a 
clean coal technology demonstration project that is operated for a 
period of 5 years or less, and which complies with the State 
implementation plan for the State in which the project is located and 
other requirements necessary to attain and maintain the national ambient 
air quality standards during and after the project is terminated.
    (36)(i) Repowering means replacement of an existing coal-fired 
boiler with one of the following clean coal technologies: atmospheric or 
pressurized fluidized bed combustion, integrated gasification combined 
cycle, magnetohydrodynamics, direct and indirect coal-fired turbines, 
integrated gasification fuel cells, or as determined by the 
Administrator, in consultation with the Secretary of Energy, a 
derivative of one or more of these technologies, and any other 
technology capable of controlling multiple combustion emissions 
simultaneously with improved boiler or generation efficiency and with 
significantly greater waste reduction relative to the performance of 
technology in widespread commercial use as of November 15, 1990.
    (ii) Repowering shall also include any oil and/or gas-fired unit 
which has been awarded clean coal technology demonstration funding as of 
January 1, 1991, by the Department of Energy.
    (iii) The reviewing authority shall give expedited consideration to 
permit applications for any source that satisfies the requirements of 
this subsection and is granted an extension under section 409 of the 
Clean Air Act.
    (37) Reactivation of a very clean coal-fired electric utility steam 
generating unit means any physical change or change in the method of 
operation associated with the commencement of commercial operations by a 
coal-fired utility unit after a period of discontinued operation where 
the unit:
    (i) Has not been in operation for the two-year period prior to the 
enactment of the Clean Air Act Amendments of 1990, and the emissions 
from such unit continue to be carried in the permitting authority's 
emissions inventory at the time of enactment;
    (ii) Was equipped prior to shutdown with a continuous system of 
emissions control that achieves a removal efficiency for sulfur dioxide 
of no less than 85 percent and a removal efficiency for particulates of 
no less than 98 percent;
    (iii) Is equipped with low-NOX burners prior to the time 
of commencement of operations following reactivation; and
    (iv) Is otherwise in compliance with the requirements of the Clean 
Air Act.
    (38) Pollution prevention means any activity that through process 
changes, product reformulation or redesign, or substitution of less 
polluting raw materials, eliminates or reduces the release of air 
pollutants (including fugitive emissions) and other pollutants to the 
environment prior to recycling, treatment, or disposal; it does not mean 
recycling (other than certain ``in-process recycling'' practices), 
energy recovery, treatment, or disposal.
    (39) Significant emissions increase means, for a regulated NSR 
pollutant, an increase in emissions that is significant (as defined in 
paragraph (b)(23) of this section) for that pollutant.
    (40)(i) Projected actual emissions means the maximum annual rate, in 
tons per year, at which an existing emissions unit is projected to emit 
a regulated NSR pollutant in any one of the 5 years (12-month period) 
following the date the unit resumes regular operation after the project, 
or in any one of the 10 years following that date, if the project 
involves increasing the emissions unit's design capacity or its 
potential to emit that regulated NSR pollutant, and full utilization of 
the unit would result in a significant emissions increase, or a 
significant net emissions increase at the major stationary source.
    (ii) In determining the projected actual emissions under paragraph 
(b)(40)(i) of this section (before beginning actual construction), the 
owner or

[[Page 270]]

operator of the major stationary source:
    (a) Shall consider all relevant information, including but not 
limited to, historical operational data, the company's own 
representations, the company's expected business activity and the 
company's highest projections of business activity, the company's 
filings with the State or Federal regulatory authorities, and compliance 
plans under the approved plan; and
    (b) Shall include fugitive emissions to the extent quantifiable, and 
emissions associated with startups, shutdowns, and malfunctions; and
    (c) Shall exclude, in calculating any increase in emissions that 
results from the particular project, that portion of the unit's 
emissions following the project that an existing unit could have 
accommodated during the consecutive 24-month period used to establish 
the baseline actual emissions under paragraph (b)(47) of this section 
and that are also unrelated to the particular project, including any 
increased utilization due to product demand growth; or,
    (d) In lieu of using the method set out in paragraphs (b)(40)(ii)(a) 
through (c) of this section, may elect to use the emissions unit's 
potential to emit, in tons per year, as defined under paragraph (b)(4) 
of this section.
    (41) [Reserved]
    (42) Prevention of Significant Deterioration Program (PSD) program 
means a major source preconstruction permit program that has been 
approved by the Administrator and incorporated into the plan to 
implement the requirements of this section, or the program in Sec. 
52.21 of this chapter. Any permit issued under such a program is a major 
NSR permit.
    (43) Continuous emissions monitoring system (CEMS) means all of the 
equipment that may be required to meet the data acquisition and 
availability requirements of this section, to sample, condition (if 
applicable), analyze, and provide a record of emissions on a continuous 
basis.
    (44) Predictive emissions monitoring system (PEMS) means all of the 
equipment necessary to monitor process and control device operational 
parameters (for example, control device secondary voltages and electric 
currents) and other information (for example, gas flow rate, O\2\ or 
CO\2\ concentrations), and calculate and record the mass emissions rate 
(for example, lb/hr) on a continuous basis.
    (45) Continuous parameter monitoring system (CPMS) means all of the 
equipment necessary to meet the data acquisition and availability 
requirements of this section, to monitor process and control device 
operational parameters (for example, control device secondary voltages 
and electric currents) and other information (for example, gas flow 
rate, O\2\ or CO\2\ concentrations), and to record average operational 
parameter value(s) on a continuous basis.
    (46) Continuous emissions rate monitoring system (CERMS) means the 
total equipment required for the determination and recording of the 
pollutant mass emissions rate (in terms of mass per unit of time).
    (47) Baseline actual emissions means the rate of emissions, in tons 
per year, of a regulated NSR pollutant, as determined in accordance with 
paragraphs (b)(47)(i) through (iv) of this section.
    (i) For any existing electric utility steam generating unit, 
baseline actual emissions means the average rate, in tons per year, at 
which the unit actually emitted the pollutant during any consecutive 24-
month period selected by the owner or operator within the 5-year period 
immediately preceding when the owner or operator begins actual 
construction of the project. The reviewing authority shall allow the use 
of a different time period upon a determination that it is more 
representative of normal source operation.
    (a) The average rate shall include fugitive emissions to the extent 
quantifiable, and emissions associated with startups, shutdowns, and 
malfunctions.
    (b) The average rate shall be adjusted downward to exclude any non-
compliant emissions that occurred while the source was operating above 
an emission limitation that was legally enforceable during the 
consecutive 24-month period.
    (c) For a regulated NSR pollutant, when a project involves multiple 
emissions units, only one consecutive 24-month period must be used to 
determine the baseline actual emissions for

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the emissions units being changed. A different consecutive 24-month 
period can be used For each regulated NSR pollutant.
    (d) The average rate shall not be based on any consecutive 24-month 
period for which there is inadequate information for determining annual 
emissions, in tons per year, and for adjusting this amount if required 
by paragraph (b)(47)(i)(b) of this section.
    (ii) For an existing emissions unit (other than an electric utility 
steam generating unit), baseline actual emissions means the average 
rate, in tons per year, at which the emissions unit actually emitted the 
pollutant during any consecutive 24-month period selected by the owner 
or operator within the 10-year period immediately preceding either the 
date the owner or operator begins actual construction of the project, or 
the date a complete permit application is received by the reviewing 
authority for a permit required either under this section or under a 
plan approved by the Administrator, whichever is earlier, except that 
the 10-year period shall not include any period earlier than November 
15, 1990.
    (a) The average rate shall include fugitive emissions to the extent 
quantifiable, and emissions associated with startups, shutdowns, and 
malfunctions.
    (b) The average rate shall be adjusted downward to exclude any non-
compliant emissions that occurred while the source was operating above 
an emission limitation that was legally enforceable during the 
consecutive 24-month period.
    (c) The average rate shall be adjusted downward to exclude any 
emissions that would have exceeded an emission limitation with which the 
major stationary source must currently comply, had such major stationary 
source been required to comply with such limitations during the 
consecutive 24-month period. However, if an emission limitation is part 
of a maximum achievable control technology standard that the 
Administrator proposed or promulgated under part 63 of this chapter, the 
baseline actual emissions need only be adjusted if the State has taken 
credit for such emissions reductions in an attainment demonstration or 
maintenance plan consistent with the requirements of Sec. 
51.165(a)(3)(ii)(G).
    (d) For a regulated NSR pollutant, when a project involves multiple 
emissions units, only one consecutive 24-month period must be used to 
determine the baseline actual emissions for the emissions units being 
changed. A different consecutive 24-month period can be used For each 
regulated NSR pollutant.
    (e) The average rate shall not be based on any consecutive 24-month 
period for which there is inadequate information for determining annual 
emissions, in tons per year, and for adjusting this amount if required 
by paragraphs (b)(47)(ii)(b) and (c) of this section.
    (iii) For a new emissions unit, the baseline actual emissions for 
purposes of determining the emissions increase that will result from the 
initial construction and operation of such unit shall equal zero; and 
thereafter, for all other purposes, shall equal the unit's potential to 
emit.
    (iv) For a PAL for a stationary source, the baseline actual 
emissions shall be calculated for existing electric utility steam 
generating units in accordance with the procedures contained in 
paragraph (b)(47)(i) of this section, for other existing emissions units 
in accordance with the procedures contained in paragraph (b)(47)(ii) of 
this section, and for a new emissions unit in accordance with the 
procedures contained in paragraph (b)(47)(iii) of this section.
    (48) Subject to regulation means, for any air pollutant, that the 
pollutant is subject to either a provision in the Clean Air Act, or a 
nationally-applicable regulation codified by the Administrator in 
subchapter C of this chapter, that requires actual control of the 
quantity of emissions of that pollutant, and that such a control 
requirement has taken effect and is operative to control, limit or 
restrict the quantity of emissions of that pollutant released from the 
regulated activity. Except that:
    (i) Greenhouse gases (GHGs), the air pollutant defined in Sec. 
86.1818-12(a) of this chapter as the aggregate group of six greenhouse 
gases: Carbon dioxide, nitrous oxide, methane,

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hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride, shall not 
be subject to regulation except as provided in paragraphs (b)(48)(iv) 
through (v) of this section.
    (ii) For purposes of paragraphs (b)(48)(iii) through (v) of this 
section, the term tpy CO2 equivalent emissions 
(CO2e) shall represent an amount of GHGs emitted, and shall 
be computed as follows:
    (a) Multiplying the mass amount of emissions (tpy), for each of the 
six greenhouse gases in the pollutant GHGs, by the gas's associated 
global warming potential published at Table A-1 to subpart A of part 98 
of this chapter--Global Warming Potentials. For purposes of this 
paragraph (b)(48)(ii)(a), prior to July 21, 2014, the mass of the 
greenhouse gas carbon dioxide shall not include carbon dioxide emissions 
resulting from the combustion or decomposition of non-fossilized and 
biodegradable organic material originating from plants, animals, or 
micro-organisms (including products, by-products, residues and waste 
from agriculture, forestry and related industries as well as the non-
fossilized and biodegradable organic fractions of industrial and 
municipal wastes, including gases and liquids recovered from the 
decomposition of non-fossilized and biodegradable organic material).
    (b) Sum the resultant value from paragraph (b)(48)(ii)(a) of this 
section for each gas to compute a tpy CO2e.
    (iii) The term emissions increase as used in paragraphs (b)(48)(iv) 
through (v) of this section shall mean that both a significant emissions 
increase (as calculated using the procedures in (a)(7)(iv) of this 
section) and a significant net emissions increase (as defined in 
paragraphs (b)(3) and (b)(23) of this section) occur. For the pollutant 
GHGs, an emissions increase shall be based on tpy CO2e, and 
shall be calculated assuming the pollutant GHGs is a regulated NSR 
pollutant, and ``significant'' is defined as 75,000 tpy CO2e 
instead of applying the value in paragraph (b)(23)(ii) of this section.
    (iv) Beginning January 2, 2011, the pollutant GHGs is subject to 
regulation if:
    (a) The stationary source is a new major stationary source for a 
regulated NSR pollutant that is not GHGs, and also will emit or will 
have the potential to emit 75,000 tpy CO2e or more; or
    (b) The stationary source is an existing major stationary source for 
a regulated NSR pollutant that is not GHGs, and also will have an 
emissions increase of a regulated NSR pollutant, and an emissions 
increase of 75,000 tpy CO2e or more; and,
    (49) Regulated NSR pollutant, for purposes of this section, means 
the following:
    (i) Any pollutant for which a national ambient air quality standard 
has been promulgated. This includes, but is not limited to, the 
following:
    (a) PM2.5 emissions and PM10 emissions shall 
include gaseous emissions from a source or activity which condense to 
form particulate matter at ambient temperatures. On or after January 1, 
2011, such condensable particulate matter shall be accounted for in 
applicability determinations and in establishing emissions limitations 
for PM2.5 and PM10 in PSD permits. Compliance with 
emissions limitations for PM2.5 and PM10 issued 
prior to this date shall not be based on condensable particulate matter 
unless required by the terms and conditions of the permit or the 
applicable implementation plan. Applicability determinations made prior 
to this date without accounting for condensable particulate matter shall 
not be considered in violation of this section unless the applicable 
implementation plan required condensable particulate matter to be 
included;
    (b) Any pollutant identified under this paragraph (b)(49)(i)(b) as a 
constituent or precursor to a pollutant for which a national ambient air 
quality standard has been promulgated. Precursors identified by the 
Administrator for purposes of NSR are the following:
    (1) Volatile organic compounds and nitrogen oxides are precursors to 
ozone in all attainment and unclassifiable areas.
    (2) Sulfur dioxide is a precursor to PM2.5 in all 
attainment and unclassifiable areas.
    (3) Nitrogen oxides are presumed to be precursors to 
PM2.5 in all attainment and unclassifiable areas, unless

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the State demonstrates to the Administrator's satisfaction or EPA 
demonstrates that emissions of nitrogen oxides from sources in a 
specific area are not a significant contributor to that area's ambient 
PM2.5 concentrations.
    (4) Volatile organic compounds are presumed not to be precursors to 
PM2.5 in any attainment or unclassifiable area, unless the 
State demonstrates to the Administrator's satisfaction or EPA 
demonstrates that emissions of volatile organic compounds from sources 
in a specific area are a significant contributor to that area's ambient 
PM2.5 concentrations.
    (ii) Any pollutant that is subject to any standard promulgated under 
section 111 of the Act;
    (iii) Any Class I or II substance subject to a standard promulgated 
under or established by title VI of the Act;
    (iv) Any pollutant that otherwise is subject to regulation under the 
Act as defined in paragraph (b)(48) of this section.
    (v) Notwithstanding paragraphs (b)(49)(i) through (iv) of this 
section, the term regulated NSR pollutant shall not include any or all 
hazardous air pollutants either listed in section 112 of the Act, or 
added to the list pursuant to section 112(b)(2) of the Act, and which 
have not been delisted pursuant to section 112(b)(3) of the Act, unless 
the listed hazardous air pollutant is also regulated as a constituent or 
precursor of a general pollutant listed under section 108 of the Act.
    (50) Reviewing authority means the State air pollution control 
agency, local agency, other State agency, Indian tribe, or other agency 
authorized by the Administrator to carry out a permit program under 
Sec. 51.165 and this section, or the Administrator in the case of EPA-
implemented permit programs under Sec. 52.21 of this chapter.
    (51) Project means a physical change in, or change in method of 
operation of, an existing major stationary source.
    (52) Lowest achievable emission rate (LAER) is as defined in Sec. 
51.165(a)(1)(xiii).
    (53)(i) In general, process unit means any collection of structures 
and/or equipment that processes, assembles, applies, blends, or 
otherwise uses material inputs to produce or store an intermediate or a 
completed product. A single stationary source may contain more than one 
process unit, and a process unit may contain more than one emissions 
unit.
    (ii) Pollution control equipment is not part of the process unit, 
unless it serves a dual function as both process and control equipment. 
Administrative and warehousing facilities are not part of the process 
unit.
    (iii) For replacement cost purposes, components shared between two 
or more process units are proportionately allocated based on capacity.
    (iv) The following list identifies the process units at specific 
categories of stationary sources.
    (a) For a steam electric generating facility, the process unit 
consists of those portions of the plant that contribute directly to the 
production of electricity. For example, at a pulverized coal-fired 
facility, the process unit would generally be the combination of those 
systems from the coal receiving equipment through the emission stack 
(excluding post-combustion pollution controls), including the coal 
handling equipment, pulverizers or coal crushers, feedwater heaters, ash 
handling, boiler, burners, turbine-generator set, condenser, cooling 
tower, water treatment system, air preheaters, and operating control 
systems. Each separate generating unit is a separate process unit.
    (b) For a petroleum refinery, there are several categories of 
process units: those that separate and/or distill petroleum feedstocks; 
those that change molecular structures; petroleum treating processes; 
auxiliary facilities, such as steam generators and hydrogen production 
units; and those that load, unload, blend or store intermediate or 
completed products.
    (c) For an incinerator, the process unit would consist of components 
from the feed pit or refuse pit to the stack, including conveyors, 
combustion devices, heat exchangers and steam generators, quench tanks, 
and fans.

    Note to paragraph (b)(53): By a court order on December 24, 2003, 
this paragraph (b)(53) is stayed indefinitely. The stayed provisions 
will become effective immediately if the court terminates the stay. At 
that time,

[[Page 274]]

EPA will publish a document in the Federal Register advising the public 
of the termination of the stay.

    (54) Functionally equivalent component means a component that serves 
the same purpose as the replaced component.

    Note to paragraph (b)(54): By a court order on December 24, 2003, 
this paragraph (b)(54) is stayed indefinitely. The stayed provisions 
will become effective immediately if the court terminates the stay. At 
that time, EPA will publish a document in the Federal Register advising 
the public of the termination of the stay.

    (55) Fixed capital cost means the capital needed to provide all the 
depreciable components. ``Depreciable components'' refers to all 
components of fixed capital cost and is calculated by subtracting land 
and working capital from the total capital investment, as defined in 
paragraph (b)(56) of this section.

    Note to paragraph (b)(55): By a court order on December 24, 2003, 
this paragraph (b)(55) is stayed indefinitely. The stayed provisions 
will become effective immediately if the court terminates the stay. At 
that time, EPA will publish a document in the Federal Register advising 
the public of the termination of the stay.

    (56) Total capital investment means the sum of the following: all 
costs required to purchase needed process equipment (purchased equipment 
costs); the costs of labor and materials for installing that equipment 
(direct installation costs); the costs of site preparation and 
buildings; other costs such as engineering, construction and field 
expenses, fees to contractors, startup and performance tests, and 
contingencies (indirect installation costs); land for the process 
equipment; and working capital for the process equipment.

    Note to paragraph (b)(56): By a court order on December 24, 2003, 
this paragraph (b)(56) is stayed indefinitely. The stayed provisions 
will become effective immediately if the court terminates the stay. At 
that time, EPA will publish a document in the Federal Register advising 
the public of the termination of the stay.

    (c) Ambient air increments and other measures. (1) The plan shall 
contain emission limitations and such other measures as may be necessary 
to assure that in areas designated as Class I, II, or III, increases in 
pollutant concentrations over the baseline concentration shall be 
limited to the following:

------------------------------------------------------------------------
                                                              Maximum
                                                             allowable
                                                             increase
                        Pollutant                           (micrograms
                                                             per cubic
                                                              meter)
------------------------------------------------------------------------
                              Class I Area
------------------------------------------------------------------------
PM2.5:
    Annual arithmetic mean..............................               1
    24-hr maximum.......................................               2
PM10:
    Annual arithmetic mean..............................               4
    24-hr maximum.......................................               8
Sulfur dioxide:
    Annual arithmetic mean..............................               2
    24-hr maximum.......................................               5
    3-hr maximum........................................              25
Nitrogen dioxide:
    Annual arithmetic mean..............................             2.5
------------------------------------------------------------------------
                              Class II Area
------------------------------------------------------------------------
PM2.5:
    Annual arithmetic mean..............................               4
    24-hr maximum.......................................               9
PM10:
    Annual arithmetic mean..............................              17
    24-hr maximum.......................................              30
Sulfur dioxide:
    Annual arithmetic mean..............................              20
    24-hr maximum.......................................              91
    3-hr maximum........................................             512
Nitrogen dioxide:

[[Page 275]]

 
    Annual arithmetic mean..............................              25
------------------------------------------------------------------------
                             Class III Area
------------------------------------------------------------------------
PM2.5:
    Annual arithmetic mean..............................               8
    24-hr maximum.......................................              18
PM10:
    Annual arithmetic mean..............................              34
    24-hr maximum.......................................              60
Sulfur dioxide:
    Annual arithmetic mean..............................              40
    24-hr maximum.......................................             182
    3-hr maximum........................................             700
Nitrogen dioxide:
    Annual arithmetic mean..............................              50
------------------------------------------------------------------------

    For any period other than an annual period, the applicable maximum 
allowable increase may be exceeded during one such period per year at 
any one location.
    (2) Where the State can demonstrate that it has alternative measures 
in its plan other than maximum allowable increases as defined under 
paragraph (c)(1) of this section, that satisfy the requirements in 
sections 166(c) and 166(d) of the Clean Air Act for a regulated NSR 
pollutant for which the Administrator has established maximum allowable 
increases pursuant to section 166(a) of the Act, the requirements for 
maximum allowable increases for that pollutant under paragraph (c)(1) of 
this section shall not apply upon approval of the plan by the 
Administrator. The following regulated NSR pollutants are eligible for 
such treatment:
    (i) Nitrogen dioxide.
    (ii) PM2.5.
    (d) Ambient air ceilings. The plan shall provide that no 
concentration of a pollutant shall exceed:
    (1) The concentration permitted under the national secondary ambient 
air quality standard, or
    (2) The concentration permitted under the national primary ambient 
air quality standard, whichever concentration is lowest for the 
pollutant for a period of exposure.
    (e) Restrictions on area classifications. The plan shall provide 
that--
    (1) All of the following areas which were in existence on August 7, 
1977, shall be Class I areas and may not be redesignated:
    (i) International parks,
    (ii) National wilderness areas which exceed 5,000 acres in size,
    (iii) National memorial parks which exceed 5,000 acres in size, and
    (iv) National parks which exceed 6,000 acres in size.
    (2) Areas which were redesignated as Class I under regulations 
promulgated before August 7, 1977, shall remain Class I, but may be 
redesignated as provided in this section.
    (3) Any other area, unless otherwise specified in the legislation 
creating such an area, is initially designated Class II, but may be 
redesignated as provided in this section.
    (4) The following areas may be redesignated only as Class I or II:
    (i) An area which as of August 7, 1977, exceeded 10,000 acres in 
size and was a national monument, a national primitive area, a national 
preserve, a national recreational area, a national wild and scenic 
river, a national wildlife refuge, a national lakeshore or seashore; and
    (ii) A national park or national wilderness area established after 
August 7, 1977, which exceeds 10,000 acres in size.
    (f) Exclusions from increment consumption. (1) The plan may provide 
that the following concentrations shall be excluded in determining 
compliance with a maximum allowable increase:
    (i) Concentrations attributable to the increase in emissions from 
stationary

[[Page 276]]

sources which have converted from the use of petroleum products, natural 
gas, or both by reason of an order in effect under section 2 (a) and (b) 
of the Energy Supply and Environmental Coordination Act of 1974 (or any 
superseding legislation) over the emissions from such sources before the 
effective date of such an order;
    (ii) Concentrations attributable to the increase in emissions from 
sources which have converted from using natural gas by reason of natural 
gas curtailment plan in effect pursuant to the Federal Power Act over 
the emissions from such sources before the effective date of such plan;
    (iii) Concentrations of particulate matter attributable to the 
increase in emissions from construction or other temporary emission-
related activities of new or modified sources;
    (iv) The increase in concentrations attributable to new sources 
outside the United States over the concentrations attributable to 
existing sources which are included in the baseline concentration; and
    (v) Concentrations attributable to the temporary increase in 
emissions of sulfur dioxide, particulate matter, or nitrogen oxides from 
stationary sources which are affected by plan revisions approved by the 
Administrator as meeting the criteria specified in paragraph (f)(4) of 
this section.
    (2) If the plan provides that the concentrations to which paragraph 
(f)(1) (i) or (ii) of this section, refers shall be excluded, it shall 
also provide that no exclusion of such concentrations shall apply more 
than five years after the effective date of the order to which paragraph 
(f)(1)(i) of this section, refers or the plan to which paragraph 
(f)(1)(ii) of this section, refers, whichever is applicable. If both 
such order and plan are applicable, no such exclusion shall apply more 
than five years after the later of such effective dates.
    (3) [Reserved]
    (4) For purposes of excluding concentrations pursuant to paragraph 
(f)(1)(v) of this section, the Administrator may approve a plan revision 
that:
    (i) Specifies the time over which the temporary emissions increase 
of sulfur dioxide, particulate matter, or nitrogen oxides would occur. 
Such time is not to exceed 2 years in duration unless a longer time is 
approved by the Administrator.
    (ii) Specifies that the time period for excluding certain 
contributions in accordance with paragraph (f)(4)(i) of this section, is 
not renewable;
    (iii) Allows no emissions increase from a stationary source which 
would:
    (a) Impact a Class I area or an area where an applicable increment 
is known to be violated; or
    (b) Cause or contribute to the violation of a national ambient air 
quality standard;
    (iv) Requires limitations to be in effect the end of the time period 
specified in accordance with paragraph (f)(4)(i) of this section, which 
would ensure that the emissions levels from stationary sources affected 
by the plan revision would not exceed those levels occurring from such 
sources before the plan revision was approved.
    (g) Redesignation. (1) The plan shall provide that all areas of the 
State (except as otherwise provided under paragraph (e) of this section) 
shall be designated either Class I, Class II, or Class III. Any 
designation other than Class II shall be subject to the redesignation 
procedures of this paragraph. Redesignation (except as otherwise 
precluded by paragraph (e) of this section) may be proposed by the 
respective States or Indian Governing Bodies, as provided below, subject 
to approval by the Administrator as a revision to the applicable State 
implementation plan.
    (2) The plan may provide that the State may submit to the 
Administrator a proposal to redesignate areas of the State Class I or 
Class II: Provided, That:
    (i) At least one public hearing has been held in accordance with 
procedures established in Sec. 51.102.
    (ii) Other States, Indian Governing Bodies, and Federal Land 
Managers whose lands may be affected by the proposed redesignation were 
notified at least 30 days prior to the public hearing;
    (iii) A discussion of the reasons for the proposed redesignation, 
including a satisfactory description and analysis of the health, 
environmental, economic,

[[Page 277]]

social, and energy effects of the proposed redesignation, was prepared 
and made available for public inspection at least 30 days prior to the 
hearing and the notice announcing the hearing contained appropriate 
notification of the availability of such discussion;
    (iv) Prior to the issuance of notice respecting the redesignation of 
an area that includes any Federal lands, the State has provided written 
notice to the appropriate Federal Land Manager and afforded adequate 
opportunity (not in excess of 60 days) to confer with the State 
respecting the redesignation and to submit written comments and 
recommendations. In redesignating any area with respect to which any 
Federal Land Manager had submitted written comments and recommendations, 
the State shall have published a list of any inconsistency between such 
redesignation and such comments and recommendations (together with the 
reasons for making such redesignation against the recommendation of the 
Federal Land Manager); and
    (v) The State has proposed the redesignation after consultation with 
the elected leadership of local and other substate general purpose 
governments in the area covered by the proposed redesignation.
    (3) The plan may provide that any area other than an area to which 
paragraph (e) of this section refers may be redesignated as Class III 
if--
    (i) The redesignation would meet the requirements of provisions 
established in accordance with paragraph (g)(2) of this section;
    (ii) The redesignation, except any established by an Indian 
Governing Body, has been specifically approved by the Governor of the 
State, after consultation with the appropriate committees of the 
legislature, if it is in session, or with the leadership of the 
legislature, if it is not in session (unless State law provides that 
such redesignation must be specifically approved by State legislation) 
and if general purpose units of local government representing a majority 
of the residents of the area to be redesignated enact legislation 
(including resolutions where appropriate) concurring in the 
redesignation;
    (iii) The redesignation would not cause, or contribute to, a 
concentration of any air pollutant which would exceed any maximum 
allowable increase permitted under the classification of any other area 
or any national ambient air quality standard; and
    (iv) Any permit application for any major stationary source or major 
modification subject to provisions established in accordance with 
paragraph (l) of this section which could receive a permit only if the 
area in question were redesignated as Class III, and any material 
submitted as part of that application, were available, insofar as was 
practicable, for public inspection prior to any public hearing on 
redesignation of any area as Class III.
    (4) The plan shall provide that lands within the exterior boundaries 
of Indian Reservations may be redesignated only by the appropriate 
Indian Governing Body. The appropriate Indian Governing Body may submit 
to the Administrator a proposal to redesignate areas Class I, Class II, 
or Class III: Provided, That:
    (i) The Indian Governing Body has followed procedures equivalent to 
those required of a State under paragraphs (g) (2), (3)(iii), and 
(3)(iv) of this section; and
    (ii) Such redesignation is proposed after consultation with the 
State(s) in which the Indian Reservation is located and which border the 
Indian Reservation.
    (5) The Administrator shall disapprove, within 90 days of 
submission, a proposed redesignation of any area only if he finds, after 
notice and opportunity for public hearing, that such redesignation does 
not meet the procedural requirements of this section or is inconsistent 
with paragraph (e) of this section. If any such disapproval occurs, the 
classification of the area shall be that which was in effect prior to 
the redesignation which was disapproved.
    (6) If the Administrator disapproves any proposed area designation, 
the State or Indian Governing Body, as appropriate, may resubmit the 
proposal after correcting the deficiencies noted by the Administrator.
    (h) Stack heights. The plan shall provide, as a minimum, that the 
degree of emission limitation required for control of any air pollutant 
under the plan

[[Page 278]]

shall not be affected in any manner by--
    (1) So much of a stack height, not in existence before December 31, 
1970, as exceeds good engineering practice, or
    (2) Any other dispersion technique not implemented before then.
    (i) Exemptions. (1) The plan may provide that requirements 
equivalent to those contained in paragraphs (j) through (r) of this 
section do not apply to a particular major stationary source or major 
modification if:
    (i) The major stationary source would be a nonprofit health or 
nonprofit educational institution or a major modification that would 
occur at such an institution; or
    (ii) The source or modification would be a major stationary source 
or major modification only if fugitive emissions, to the extent 
quantifiable, are considered in calculating the potential to emit of the 
stationary source or modification and such source does not belong to any 
of the following categories:
    (a) Coal cleaning plants (with thermal dryers);
    (b) Kraft pulp mills;
    (c) Portland cement plants;
    (d) Primary zinc smelters;
    (e) Iron and steel mills;
    (f) Primary aluminum ore reduction plants;
    (g) Primary copper smelters;
    (h) Municipal incinerators capable of charging more than 250 tons of 
refuse per day;
    (i) Hydrofluoric, sulfuric, or nitric acid plants;
    (j) Petroleum refineries;
    (k) Lime plants;
    (l) Phosphate rock processing plants;
    (m) Coke oven batteries;
    (n) Sulfur recovery plants;
    (o) Carbon black plants (furnace process);
    (p) Primary lead smelters;
    (q) Fuel conversion plants;
    (r) Sintering plants;
    (s) Secondary metal production plants;
    (t) Chemical process plants--The term chemical processing plant 
shall not include ethanol production facilities that produce ethanol by 
natural fermentation included in NAICS codes 325193 or 312140;
    (u) Fossil-fuel boilers (or combination thereof) totaling more than 
250 million British thermal units per hour heat input;
    (v) Petroleum storage and transfer units with a total storage 
capacity exceeding 300,000 barrels;
    (w) Taconite ore processing plants;
    (x) Glass fiber processing plants;
    (y) Charcoal production plants;
    (z) Fossil fuel-fired steam electric plants of more than 250 million 
British thermal units per hour heat input;
    (aa) Any other stationary source category which, as of August 7, 
1980, is being regulated under section 111 or 112 of the Act; or
    (iii) The source or modification is a portable stationary source 
which has previously received a permit under requirements equivalent to 
those contained in paragraphs (j) through (r) of this section, if:
    (a) The source proposes to relocate and emissions of the source at 
the new location would be temporary; and
    (b) The emissions from the source would not exceed its allowable 
emissions; and
    (c) The emissions from the source would impact no Class I area and 
no area where an applicable increment is known to be violated; and
    (d) Reasonable notice is given to the reviewing authority prior to 
the relocation identifying the proposed new location and the probable 
duration of operation at the new location. Such notice shall be given to 
the reviewing authority not less than 10 days in advance of the proposed 
relocation unless a different time duration is previously approved by 
the reviewing authority.
    (2) The plan may provide that requirements equivalent to those 
contained in paragraphs (j) through (r) of this section do not apply to 
a major stationary source or major modification with respect to a 
particular pollutant if the owner or operator demonstrates that, as to 
that pollutant, the source or modification is located in an area 
designated as nonattainment under section 107 of the Act. Nonattainment 
designations for revoked NAAQS, as contained in part 81 of this chapter, 
shall not be viewed as current designations under section 107 of the

[[Page 279]]

Act for purposes of determining the applicability of requirements 
equivalent to those contained in paragraphs (j) through (r) of this 
section to a major stationary source or major modification after the 
revocation of that NAAQS is effective.
    (3) The plan may provide that requirements equivalent to those 
contained in paragraphs (k), (m), and (o) of this section do not apply 
to a proposed major stationary source or major modification with respect 
to a particular pollutant, if the allowable emissions of that pollutant 
from a new source, or the net emissions increase of that pollutant from 
a modification, would be temporary and impact no Class I area and no 
area where an applicable increment is known to be violated.
    (4) The plan may provide that requirements equivalent to those 
contained in paragraphs (k), (m), and (o) of this section as they relate 
to any maximum allowable increase for a Class II area do not apply to a 
modification of a major stationary source that was in existence on March 
1, 1978, if the net increase in allowable emissions of each a regulated 
NSR pollutant from the modification after the application of best 
available control technology would be less than 50 tons per year.
    (5) The plan may provide that the reviewing authority may exempt a 
proposed major stationary source or major modification from the 
requirements of paragraph (m) of this section, with respect to 
monitoring for a particular pollutant, if:
    (i) The emissions increase of the pollutant from a new stationary 
source or the net emissions increase of the pollutant from a 
modification would cause, in any area, air quality impacts less than the 
following amounts:
    (a) Carbon monoxide--575 ug/m\3\, 8-hour average;
    (b) Nitrogen dioxide--14 ug/m\3\, annual average;
    (c) PM2.5--0 [micro]g/m\3\;

    Note to paragraph (i)(5)(i)(c): In accordance with Sierra Club v. 
EPA, 706 F.3d 428 (D.C. Cir. 2013), no exemption is available with 
regard to PM2.5.

    (d) PM10-10 [micro]g/m\3\, 24-hour average;
    (e) Sulfur dioxide--13 ug/m\3\, 24-hour average;
    (f) Ozone; \1\
---------------------------------------------------------------------------

    \1\ No de minimis air quality level is provided for ozone. However, 
any net emissions increase of 100 tons per year or more of volatile 
organic compounds or nitrogen oxides subject to PSD would be required to 
perform an ambient impact analysis, including the gathering of air 
quality data.
---------------------------------------------------------------------------

    (g) Lead--0.1 [micro]g/m\3\, 3-month average.
    (h) Fluorides--0.25 [micro]g/m\3\, 24-hour average;
    (i) Total reduced sulfur--10 [micro]g/m\3\, 1-hour average
    (j) Hydrogen sulfide--0.2 [micro]g/m\3\, 1-hour average;
    (k) Reduced sulfur compounds--10 [micro]g/m\3\, 1-hour average; or
    (ii) The concentrations of the pollutant in the area that the source 
or modification would affect are less than the concentrations listed in 
paragraph (i)(5)(i) of this section; or
    (iii) The pollutant is not listed in paragraph (i)(5)(i) of this 
section.
    (6) If EPA approves a plan revision under 40 CFR 51.166 as in effect 
before August 7, 1980, any subsequent revision which meets the 
requirements of this section may contain transition provisions which 
parallel the transition provisions of 40 CFR 52.21(i)(9), (i)(10) and 
(m)(1)(v) as in effect on that date, which provisions relate to 
requirements for best available control technology and air quality 
analyses. Any such subsequent revision may not contain any transition 
provision which in the context of the revision would operate any less 
stringently than would its counterpart in 40 CFR 52.21.
    (7) If EPA approves a plan revision under Sec. 51.166 as in effect 
[before July 31, 1987], any subsequent revision which meets the 
requirements of this section may contain transition provisions which 
parallel the transition provisions of Sec. 52.21 (i)(11), and (m)(1) 
(vii) and (viii) of this chapter as in effect on that date, these 
provisions being related to monitoring requirements for particulate 
matter. Any such subsequent revision may not contain any transition 
provision which in the context of the revision would operate any less 
stringently than would its counterpart in Sec. 52.21 of this chapter.
    (8) The plan may provide that the permitting requirements equivalent 
to those contained in paragraph (k)(1)(ii)

[[Page 280]]

of this section do not apply to a stationary source or modification with 
respect to any maximum allowable increase for nitrogen oxides if the 
owner or operator of the source or modification submitted an application 
for a permit under the applicable permit program approved or promulgated 
under the Act before the provisions embodying the maximum allowable 
increase took effect as part of the plan and the permitting authority 
subsequently determined that the application as submitted before that 
date was complete.
    (9) The plan may provide that the permitting requirements equivalent 
to those contained in paragraph (k)(1)(ii) of this section shall not 
apply to a stationary source or modification with respect to any maximum 
allowable increase for PM-10 if (i) the owner or operator of the source 
or modification submitted an application for a permit under the 
applicable permit program approved under the Act before the provisions 
embodying the maximum allowable increases for PM-10 took effect as part 
of the plan, and (ii) the permitting authority subsequently determined 
that the application as submitted before that date was complete. 
Instead, the applicable requirements equivalent to paragraph (k)(1)(ii) 
shall apply with respect to the maximum allowable increases for TSP as 
in effect on the date the application was submitted.
    (10) The plan may provide that the requirements of paragraph (k)(1) 
of this section shall not apply to a stationary source or modification 
with respect to the national ambient air quality standards for 
PM2.5 in effect on March 18, 2013 if:
    (i) The reviewing authority has determined a permit application 
subject to this section to be complete on or before December 14, 2012. 
Instead, the requirements in paragraph (k)(1) of this section shall 
apply with respect to the national ambient air quality standards for 
PM2.5 in effect at the time the reviewing authority 
determined the permit application to be complete; or
    (ii) The reviewing authority has first published before March 18, 
2013 a public notice of a preliminary determination for the permit 
application subject to this section. Instead, the requirements in 
paragraph (k)(1) of this section shall apply with respect to the 
national ambient air quality standards for PM2.5 in effect at 
the time of first publication of a public notice on the preliminary 
determination.
    (11) The plan may provide that the requirements of paragraph (k)(1) 
of this section shall not apply to a permit application for a stationary 
source or modification with respect to the revised national ambient air 
quality standards for ozone published on October 26, 2015 if:
    (i) The reviewing authority has determined the permit application 
subject to this section to be complete on or before October 1, 2015. 
Instead, the requirements in paragraph (k)(1) of this section shall 
apply with respect to the national ambient air quality standards for 
ozone in effect at the time the reviewing authority determined the 
permit application to be complete; or
    (ii) The reviewing authority has first published before December 28, 
2015 a public notice of a preliminary determination or draft permit for 
the permit application subject to this section. Instead, the 
requirements in paragraph (k)(1) of this section shall apply with 
respect to the national ambient air quality standards for ozone in 
effect at the time of first publication of a public notice of the 
preliminary determination or draft permit.
    (j) Control technology review. The plan shall provide that:
    (1) A major stationary source or major modification shall meet each 
applicable emissions limitation under the State Implementation Plan and 
each applicable emission standards and standard of performance under 40 
CFR parts 60 and 61.
    (2) A new major stationary source shall apply best available control 
technology for each a regulated NSR pollutant that it would have the 
potential to emit in significant amounts.
    (3) A major modification shall apply best available control 
technology for each a regulated NSR pollutant for which it would be a 
significant net emissions increase at the source. This requirement 
applies to each proposed emissions unit at which a net emissions 
increase in the pollutant would occur as a result of a physical change

[[Page 281]]

or change in the method of operation in the unit.
    (4) For phased construction projects, the determination of best 
available control technology shall be reviewed and modified as 
appropriate at the least reasonable time which occurs no later than 18 
months prior to commencement of construction of each independent phase 
of the project. At such time, the owner or operator of the applicable 
stationary source may be required to demonstrate the adequacy of any 
previous determination of best available control technology for the 
source.
    (k) Source impact analysis--(1) Required demonstration. The plan 
shall provide that the owner or operator of the proposed source or 
modification shall demonstrate that allowable emission increases from 
the proposed source or modification, in conjunction with all other 
applicable emissions increases or reduction (including secondary 
emissions), would not cause or contribute to air pollution in violation 
of:
    (i) Any national ambient air quality standard in any air quality 
control region; or
    (ii) Any applicable maximum allowable increase over the baseline 
concentration in any area.
    (2) [Reserved]
    (l) Air quality models. The plan shall provide for procedures which 
specify that--
    (1) All applications of air quality modeling involved in this 
subpart shall be based on the applicable models, data bases, and other 
requirements specified in appendix W of this part (Guideline on Air 
Quality Models).
    (2) Where an air quality model specified in appendix W of this part 
(Guideline on Air Quality Models) is inappropriate, the model may be 
modified or another model substituted. Such a modification or 
substitution of a model may be made on a case-by-case basis or, where 
appropriate, on a generic basis for a specific State program. Written 
approval of the Administrator must be obtained for any modification or 
substitution. In addition, use of a modified or substituted model must 
be subject to notice and opportunity for public comment under procedures 
set forth in Sec. 51.102.
    (m) Air quality analysis--(1) Preapplication analysis. (i) The plan 
shall provide that any application for a permit under regulations 
approved pursuant to this section shall contain an analysis of ambient 
air quality in the area that the major stationary source or major 
modification would affect for each of the following pollutants:
    (a) For the source, each pollutant that it would have the potential 
to emit in a significant amount;
    (b) For the modification, each pollutant for which it would result 
in a significant net emissions increase.
    (ii) The plan shall provide that, with respect to any such pollutant 
for which no National Ambient Air Quality Standard exists, the analysis 
shall contain such air quality monitoring data as the reviewing 
authority determines is necessary to assess ambient air quality for that 
pollutant in any area that the emissions of that pollutant would affect.
    (iii) The plan shall provide that with respect to any such pollutant 
(other than nonmethane hydrocarbons) for which such a standard does 
exist, the analysis shall contain continuous air quality monitoring data 
gathered for purposes of determining whether emissions of that pollutant 
would cause or contribute to a violation of the standard or any maxiumum 
allowable increase.
    (iv) The plan shall provide that, in general, the continuous air 
monitoring data that is required shall have been gathered over a period 
of one year and shall represent the year preceding receipt of the 
application, except that, if the reviewing authority determines that a 
complete and adequate analysis can be accomplished with monitoring data 
gathered over a period shorter than one year (but not to be less than 
four months), the data that is required shall have been gathered over at 
least that shorter period.
    (v) The plan may provide that the owner or operator of a proposed 
major stationary source or major modification of volatile organic 
compounds who satisfies all conditions of 40 CFR part 51 appendix S, 
section IV may provide postapproval monitoring data for ozone in lieu of 
providing preconstruction

[[Page 282]]

data as required under paragraph (m)(1) of this section.
    (2) Post-construction monitoring. The plan shall provide that the 
owner or operator of a major stationary source or major modification 
shall, after construction of the stationary source or modification, 
conduct such ambient monitoring as the reviewing authority determines is 
necessary to determine the effect emissions from the stationary source 
or modification may have, or are having, on air quality in any area.
    (3) Operation of monitoring stations. The plan shall provide that 
the owner or operator of a major stationary source or major modification 
shall meet the requirements of appendix B to part 58 of this chapter 
during the operation of monitoring stations for purposes of satisfying 
paragraph (m) of this section.
    (n) Source information. (1) The plan shall provide that the owner or 
operator of a proposed source or modification shall submit all 
information necessary to perform any analysis or make any determination 
required under procedures established in accordance with this section.
    (2) The plan may provide that such information shall include:
    (i) A description of the nature, location, design capacity, and 
typical operating schedule of the source or modification, including 
specifications and drawings showing its design and plant layout;
    (ii) A detailed schedule for construction of the source or 
modification;
    (iii) A detailed description as to what system of continuous 
emission reduction is planned by the source or modification, emission 
estimates, and any other information as necessary to determine that best 
available control technology as applicable would be applied;
    (3) The plan shall provide that upon request of the State, the owner 
or operator shall also provide information on:
    (i) The air quality impact of the source or modification, including 
meteorological and topographical data necessary to estimate such impact; 
and
    (ii) The air quality impacts and the nature and extent of any or all 
general commercial, residential, industrial, and other growth which has 
occurred since August 7, 1977, in the area the source or modification 
would affect.
    (o) Additional impact analyses. The plan shall provide that--
    (1) The owner or operator shall provide an analysis of the 
impairment to visibility, soils, and vegetation that would occur as a 
result of the source or modification and general commercial, 
residential, industrial, and other growth associated with the source or 
modification. The owner or operator need not provide an analysis of the 
impact on vegetation having no significant commercial or recreational 
value.
    (2) The owner or operator shall provide an analysis of the air 
quality impact projected for the area as a result of general commercial, 
residential, industrial, and other growth associated with the source or 
modification.
    (p) Sources impacting Federal Class I areas--additional 
requirements--(1) Notice to EPA. The plan shall provide that the 
reviewing authority shall transmit to the Administrator a copy of each 
permit application relating to a major stationary source or major 
modification and provide notice to the Administrator of every action 
related to the consideration of such permit.
    (2) Federal Land Manager. The Federal Land Manager and the Federal 
official charged with direct responsibility for management of Class I 
lands have an affirmative responsibility to protect the air quality 
related values (including visibility) of any such lands and to consider, 
in consultation with the Administrator, whether a proposed source or 
modification would have an adverse impact on such values.
    (3) Denial--impact on air quality related values. The plan shall 
provide a mechanism whereby a Federal Land Manager of any such lands may 
present to the State, after the reviewing authority's preliminary 
determination required under procedures developed in accordance with 
paragraph (r) of this section, a demonstration that the emissions from 
the proposed source or modification would have an adverse impact on the 
air quality-related values (including visibility) of any Federal 
mandatory Class I lands, notwithstanding that the change in air quality 
resulting from emissions from such

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source or modification would not cause or contribute to concentrations 
which would exceed the maximum allowable increases for a Class I area. 
If the State concurs with such demonstration, the reviewing authority 
shall not issue the permit.
    (4) Class I Variances. The plan may provide that the owner or 
operator of a proposed source or modification may demonstrate to the 
Federal Land Manager that the emissions from such source would have no 
adverse impact on the air quality related values of such lands 
(including visibility), notwithstanding that the change in air quality 
resulting from emissions from such source or modification would cause or 
contribute to concentrations which would exceed the maximum allowable 
increases for a Class I area. If the Federal land manager concurs with 
such demonstration and so certifies to the State, the reviewing 
authority may: Provided, That applicable requirements are otherwise met, 
issue the permit with such emission limitations as may be necessary to 
assure that emissions of sulfur dioxide, PM2.5, 
PM10, and nitrogen oxides would not exceed the following 
maximum allowable increases over minor source baseline concentration for 
such pollutants:

------------------------------------------------------------------------
                                                              Maximum
                                                             allowable
                                                             increase
                        Pollutant                           (micrograms
                                                             per cubic
                                                              meter)
------------------------------------------------------------------------
PM2.5:
    Annual arithmetic mean..............................               4
    24-hr maximum.......................................               9
PM10:
    Annual arithmetic mean..............................              17
    24-hr maximum.......................................              30
Sulfur dioxide:
    Annual arithmetic mean..............................              20
    24-hr maximum.......................................              91
    3-hr maximum........................................             325
Nitrogen dioxide:
    Annual arithmetic mean..............................              25
------------------------------------------------------------------------

    (5) Sulfur dioxide variance by Governor with Federal Land Manager's 
concurrence. The plan may provide that--
    (i) The owner or operator of a proposed source or modification which 
cannot be approved under procedures developed pursuant to paragraph 
(q)(4) of this section may demonstrate to the Governor that the source 
or modification cannot be constructed by reason of any maximum allowable 
increase for sulfur dioxide for periods of twenty-four hours or less 
applicable to any Class I area and, in the case of Federal mandatory 
Class I areas, that a variance under this clause would not adversely 
affect the air quality related values of the area (including 
visibility);
    (ii) The Governor, after consideration of the Federal Land Manager's 
recommendation (if any) and subject to his concurrence, may grant, after 
notice and an opportunity for a public hearing, a variance from such 
maximum allowable increase; and
    (iii) If such variance is granted, the reviewing authority may issue 
a permit to such source or modification in accordance with provisions 
developed pursuant to paragraph (q)(7) of this section: Provided, That 
the applicable requirements of the plan are otherwise met.
    (6) Variance by the Governor with the President's concurrence. The 
plan may provide that--
    (i) The recommendations of the Governor and the Federal Land Manager 
shall be transferred to the President in any case where the Governor 
recommends a variance in which the Federal Land Manager does not concur;
    (ii) The President may approve the Governor's recommendation if he 
finds that such variance is in the national interest; and
    (iii) If such a variance is approved, the reviewing authority may 
issue a

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permit in accordance with provisions developed pursuant to the 
requirements of paragraph (q)(7) of this section: Provided, That the 
applicable requirements of the plan are otherwise met.
    (7) Emission limitations for Presidential or gubernatorial variance. 
The plan shall provide that in the case of a permit issued under 
procedures developed pursuant to paragraph (q) (5) or (6) of this 
section, the source or modification shall comply with emission 
limitations as may be necessary to assure that emissions of sulfur 
dioxide from the source or modification would not (during any day on 
which the otherwise applicable maximum allowable increases are exceeded) 
cause or contribute to concentrations which would exceed the following 
maximum allowable increases over the baseline concentration and to 
assure that such emissions would not cause or contribute to 
concentrations which exceed the otherwise applicable maximum allowable 
increases for periods of exposure of 24 hours or less for more than 18 
days, not necessarily consecutive, during any annual period:

                       Maximum Allowable Increase
                      [Micrograms per cubic meter]
------------------------------------------------------------------------
                                                          Terrain areas
                  Period of exposure                   -----------------
                                                          Low      High
------------------------------------------------------------------------
24-hr maximum.........................................       36       62
3-hr maximum..........................................      130      221
------------------------------------------------------------------------

    (q) Public participation. The plan shall provide that--
    (1) The reviewing authority shall notify all applicants within a 
specified time period as to the completeness of the application or any 
deficiency in the application or information submitted. In the event of 
such a deficiency, the date of receipt of the application shall be the 
date on which the reviewing authority received all required information.
    (2) Within one year after receipt of a complete application, the 
reviewing authority shall:
    (i) Make a preliminary determination whether construction should be 
approved, approved with conditions, or disapproved.
    (ii) Make available in at least one location in each region in which 
the proposed source would be constructed, a copy of all materials the 
applicant submitted, a copy of the preliminary determination, and a copy 
or summary of other materials, if any, considered in making the 
preliminary determination. This requirement may be met by making these 
materials available at a physical location or on a public Web site 
identified by the reviewing authority.
    (iii) Notify the public, by advertisement in a newspaper of general 
circulation in each region in which the proposed source would be 
constructed, of the application, the preliminary determination, the 
degree of increment consumption that is expected from the source or 
modification, and of the opportunity for comment at a public hearing as 
well as through written public comment. Alternatively, these 
notifications may be made on a public Web site identified by the 
reviewing authority. However, the reviewing authority's selected 
notification method (i.e., either newspaper or Web site), known as the 
``consistent noticing method,'' shall be used for all permits subject to 
notice under this section and may, when appropriate, be supplemented by 
other noticing methods on individual permits. If the reviewing authority 
selects Web site notice as its consistent noticing method, the notice 
shall be available for the duration of the public comment period and 
shall include the notice of public comment, the draft permit, 
information on how to access the administrative record for the draft 
permit and how to request and/or attend a public hearing on the draft 
permit.
    (iv) Send a copy of the notice of public comment to the applicant, 
the Administrator and to officials and agencies having cognizance over 
the location where the proposed construction would occur as follows: Any 
other State or local air pollution control agencies, the chief 
executives of the city and county where the source would be located; any 
comprehensive regional land use planning agency, and any State, Federal 
Land Manager, or Indian Governing body whose lands

[[Page 285]]

may be affected by emissions from the source or modification.
    (v) Provide opportunity for a public hearing for interested persons 
to appear and submit written or oral comments on the air quality impact 
of the source, alternatives to it, the control technology required, and 
other appropriate considerations.
    (vi) Consider all written comments submitted within a time specified 
in the notice of public comment and all comments received at any public 
hearing in making a final decision on the approvability of the 
application. The reviewing authority shall make all comments available 
for public inspection at the same physical location or on the same Web 
site where the reviewing authority made available preconstruction 
information relating to the proposed source or modification.
    (vii) Make a final determination whether construction should be 
approved, approved with conditions, or disapproved.
    (viii) Notify the applicant in writing of the final determination 
and make such notification available for public inspection at the same 
location or on the same Web site where the reviewing authority made 
available preconstruction information and public comments relating to 
the proposed source or modification.
    (r) Source obligation. (1) The plan shall include enforceable 
procedures to provide that approval to construct shall not relieve any 
owner or operator of the responsibility to comply fully with applicable 
provisions of the plan and any other requirements under local, State or 
Federal law.
    (2) The plan shall provide that at such time that a particular 
source or modification becomes a major stationary source or major 
modification solely by virtue of a relaxation in any enforceable 
limitation which was established after August 7, 1980, on the capacity 
of the source or modification otherwise to emit a pollutant, such as a 
restriction on hours of operation, then the requirements of paragraphs 
(j) through (s) of this section shall apply to the source or 
modification as though construction had not yet commenced on the source 
or modification.
    (3)-(5) [Reserved]
    (6) Each plan shall provide that, except as otherwise provided in 
paragraph (r)(6)(vi) of this section, the following specific provisions 
apply with respect to any regulated NSR pollutant emitted from projects 
at existing emissions units at a major stationary source (other than 
projects at a source with a PAL) in circumstances where there is a 
reasonable possibility, within the meaning of paragraph (r)(6)(vi) of 
this section, that a project that is not a part of a major modification 
may result in a significant emissions increase of such pollutant, and 
the owner or operator elects to use the method specified in paragraphs 
(b)(40)(ii)(a) through (c) of this section for calculating projected 
actual emissions. Deviations from these provisions will be approved only 
if the State specifically demonstrates that the submitted provisions are 
more stringent than or at least as stringent in all respects as the 
corresponding provisions in paragraphs (r)(6)(i) through (vi) of this 
section.
    (i) Before beginning actual construction of the project, the owner 
or operator shall document and maintain a record of the following 
information:
    (a) A description of the project;
    (b) Identification of the emissions unit(s) whose emissions of a 
regulated NSR pollutant could be affected by the project; and
    (c) A description of the applicability test used to determine that 
the project is not a major modification for any regulated NSR pollutant, 
including the baseline actual emissions, the projected actual emissions, 
the amount of emissions excluded under paragraph (b)(40)(ii)(c) of this 
section and an explanation for why such amount was excluded, and any 
netting calculations, if applicable.
    (ii) If the emissions unit is an existing electric utility steam 
generating unit, before beginning actual construction, the owner or 
operator shall provide a copy of the information set out in paragraph 
(r)(6)(i) of this section to the reviewing authority. Nothing in this 
paragraph (r)(6)(ii) shall be construed to require the owner or operator 
of such a unit to obtain any determination from the reviewing authority 
before beginning actual construction.

[[Page 286]]

    (iii) The owner or operator shall monitor the emissions of any 
regulated NSR pollutant that could increase as a result of the project 
and that is emitted by any emissions unit identified in paragraph 
(r)(6)(i)(b) of this section; and calculate and maintain a record of the 
annual emissions, in tons per year on a calendar year basis, for a 
period of 5 years following resumption of regular operations after the 
change, or for a period of 10 years following resumption of regular 
operations after the change if the project increases the design capacity 
or potential to emit of that regulated NSR pollutant at such emissions 
unit.
    (iv) If the unit is an existing electric utility steam generating 
unit, the owner or operator shall submit a report to the reviewing 
authority within 60 days after the end of each year during which records 
must be generated under paragraph (r)(6)(iii) of this section setting 
out the unit's annual emissions during the calendar year that preceded 
submission of the report.
    (v) If the unit is an existing unit other than an electric utility 
steam generating unit, the owner or operator shall submit a report to 
the reviewing authority if the annual emissions, in tons per year, from 
the project identified in paragraph (r)(6)(i) of this section, exceed 
the baseline actual emissions (as documented and maintained pursuant to 
paragraph (r)(6)(i)(c) of this section) by a significant amount (as 
defined in paragraph (b)(23) of this section) for that regulated NSR 
pollutant, and if such emissions differ from the preconstruction 
projection as documented and maintained pursuant to paragraph 
(r)(6)(i)(c) of this section. Such report shall be submitted to the 
reviewing authority within 60 days after the end of such year. The 
report shall contain the following:
    (a) The name, address and telephone number of the major stationary 
source;
    (b) The annual emissions as calculated pursuant to paragraph 
(r)(6)(iii) of this section; and
    (c) Any other information that the owner or operator wishes to 
include in the report (e.g., an explanation as to why the emissions 
differ from the preconstruction projection).
    (vi) A ``reasonable possibility'' under paragraph (r)(6) of this 
section occurs when the owner or operator calculates the project to 
result in either:
    (a) A projected actual emissions increase of at least 50 percent of 
the amount that is a ``significant emissions increase,'' as defined 
under paragraph (b)(39) of this section (without reference to the amount 
that is a significant net emissions increase), for the regulated NSR 
pollutant; or
    (b) A projected actual emissions increase that, added to the amount 
of emissions excluded under paragraph (b)(40)(ii)(c), sums to at least 
50 percent of the amount that is a ``significant emissions increase,'' 
as defined under paragraph (b)(39) of this section (without reference to 
the amount that is a significant net emissions increase), for the 
regulated NSR pollutant. For a project for which a reasonable 
possibility occurs only within the meaning of paragraph (r)(6)(vi)(b) of 
this section, and not also within the meaning of paragraph (a)(6)(vi)(a) 
of this section, then provisions (a)(6)(ii) through (v) do not apply to 
the project.
    (7) Each plan shall provide that the owner or operator of the source 
shall make the information required to be documented and maintained 
pursuant to paragraph (r)(6) of this section available for review upon 
request for inspection by the reviewing authority or the general public 
pursuant to the requirements contained in Sec. 70.4(b)(3)(viii) of this 
chapter.
    (s) Innovative control technology. (1) The plan may provide that an 
owner or operator of a proposed major stationary source or major 
modification may request the reviewing authority to approve a system of 
innovative control technology.
    (2) The plan may provide that the reviewing authority may, with the 
consent of the Governor(s) of other affected State(s), determine that 
the source or modification may employ a system of innovative control 
technology, if:
    (i) The proposed control system would not cause or contribute to an 
unreasonable risk to public health, welfare, or safety in its operation 
or function;

[[Page 287]]

    (ii) The owner or operator agrees to achieve a level of continuous 
emissions reduction equivalent to that which would have been required 
under paragraph (j)(2) of this section, by a date specified by the 
reviewing authority. Such date shall not be later than 4 years from the 
time of startup or 7 years from permit issuance;
    (iii) The source or modification would meet the requirements 
equivalent to those in paragraphs (j) and (k) of this section, based on 
the emissions rate that the stationary source employing the system of 
innovative control technology would be required to meet on the date 
specified by the reviewing authority;
    (iv) The source or modification would not before the date specified 
by the reviewing authority:
    (a) Cause or contribute to any violation of an applicable national 
ambient air quality standard; or
    (b) Impact any area where an applicable increment is known to be 
violated;
    (v) All other applicable requirements including those for public 
participation have been met.
    (vi) The provisions of paragraph (p) of this section (relating to 
Class I areas) have been satisfied with respect to all periods during 
the life of the source or modification.
    (3) The plan shall provide that the reviewing authority shall 
withdraw any approval to employ a system of innovative control 
technology made under this section, if:
    (i) The proposed system fails by the specified date to achieve the 
required continuous emissions reduction rate; or
    (ii) The proposed system fails before the specified date so as to 
contribute to an unreasonable risk to public health, welfare, or safety; 
or
    (iii) The reviewing authority decides at any time that the proposed 
system is unlikely to achieve the required level of control or to 
protect the public health, welfare, or safety.
    (4) The plan may provide that if a source or modification fails to 
meet the required level of continuous emissions reduction within the 
specified time period, or if the approval is withdrawn in accordance 
with paragraph (s)(3) of this section, the reviewing authority may allow 
the source or modification up to an additional 3 years to meet the 
requirement for the application of best available control technology 
through use of a demonstrated system of control.
    (t)-(v) [Reserved]
    (w) Actuals PALs. The plan shall provide for PALs according to the 
provisions in paragraphs (w)(1) through (15) of this section.
    (1) Applicability. (i) The reviewing authority may approve the use 
of an actuals PAL for any existing major stationary source if the PAL 
meets the requirements in paragraphs (w)(1) through (15) of this 
section. The term ``PAL'' shall mean ``actuals PAL'' throughout 
paragraph (w) of this section.
    (ii) Any physical change in or change in the method of operation of 
a major stationary source that maintains its total source-wide emissions 
below the PAL level, meets the requirements in paragraphs (w)(1) through 
(15) of this section, and complies with the PAL permit:
    (a) Is not a major modification for the PAL pollutant;
    (b) Does not have to be approved through the plan's major NSR 
program; and
    (c) Is not subject to the provisions in paragraph (r)(2) of this 
section (restrictions on relaxing enforceable emission limitations that 
the major stationary source used to avoid applicability of the major NSR 
program).
    (iii) Except as provided under paragraph (w)(1)(ii)(c) of this 
section, a major stationary source shall continue to comply with all 
applicable Federal or State requirements, emission limitations, and work 
practice requirements that were established prior to the effective date 
of the PAL.
    (2) Definitions. The plan shall use the definitions in paragraphs 
(w)(2)(i) through (xi) of this section for the purpose of developing and 
implementing regulations that authorize the use of actuals PALs 
consistent with paragraphs (w)(1) through (15) of this section. When a 
term is not defined in these paragraphs, it shall have the meaning given 
in paragraph (b) of this section or in the Act.

[[Page 288]]

    (i) Actuals PAL for a major stationary source means a PAL based on 
the baseline actual emissions (as defined in paragraph (b)(47) of this 
section) of all emissions units (as defined in paragraph (b)(7) of this 
section) at the source, that emit or have the potential to emit the PAL 
pollutant.
    (ii) Allowable emissions means ``allowable emissions'' as defined in 
paragraph (b)(16) of this section, except as this definition is modified 
according to paragraphs (w)(2)(ii)(a) and (b) of this section.
    (a) The allowable emissions for any emissions unit shall be 
calculated considering any emission limitations that are enforceable as 
a practical matter on the emissions unit's potential to emit.
    (b) An emissions unit's potential to emit shall be determined using 
the definition in paragraph (b)(4) of this section, except that the 
words ``or enforceable as a practical matter'' should be added after 
``federally enforceable.''
    (iii) Small emissions unit means an emissions unit that emits or has 
the potential to emit the PAL pollutant in an amount less than the 
significant level for that PAL pollutant, as defined in paragraph 
(b)(23) of this section or in the Act, whichever is lower.
    (iv) Major emissions unit means:
    (a) Any emissions unit that emits or has the potential to emit 100 
tons per year or more of the PAL pollutant in an attainment area; or
    (b) Any emissions unit that emits or has the potential to emit the 
PAL pollutant in an amount that is equal to or greater than the major 
source threshold for the PAL pollutant as defined by the Act for 
nonattainment areas. For example, in accordance with the definition of 
major stationary source in section 182(c) of the Act, an emissions unit 
would be a major emissions unit for VOC if the emissions unit is located 
in a serious ozone nonattainment area and it emits or has the potential 
to emit 50 or more tons of VOC per year.
    (v) Plantwide applicability limitation (PAL) means an emission 
limitation expressed in tons per year, for a pollutant at a major 
stationary source, that is enforceable as a practical matter and 
established source-wide in accordance with paragraphs (w)(1) through 
(15) of this section.
    (vi) PAL effective date generally means the date of issuance of the 
PAL permit. However, the PAL effective date for an increased PAL is the 
date any emissions unit that is part of the PAL major modification 
becomes operational and begins to emit the PAL pollutant.
    (vii) PAL effective period means the period beginning with the PAL 
effective date and ending 10 years later.
    (viii) PAL major modification means, notwithstanding paragraphs 
(b)(2) and (b)(3) of this section (the definitions for major 
modification and net emissions increase), any physical change in or 
change in the method of operation of the PAL source that causes it to 
emit the PAL pollutant at a level equal to or greater than the PAL.
    (ix) PAL permit means the major NSR permit, the minor NSR permit, or 
the State operating permit under a program that is approved into the 
plan, or the title V permit issued by the reviewing authority that 
establishes a PAL for a major stationary source.
    (x) PAL pollutant means the pollutant for which a PAL is established 
at a major stationary source.
    (xi) Significant emissions unit means an emissions unit that emits 
or has the potential to emit a PAL pollutant in an amount that is equal 
to or greater than the significant level (as defined in paragraph 
(b)(23) of this section or in the Act, whichever is lower) for that PAL 
pollutant, but less than the amount that would qualify the unit as a 
major emissions unit as defined in paragraph (w)(2)(iv) of this section.
    (3) Permit application requirements. As part of a permit application 
requesting a PAL, the owner or operator of a major stationary source 
shall submit the following information in paragraphs (w)(3)(i) through 
(iii) of this section to the reviewing authority for approval.
    (i) A list of all emissions units at the source designated as small, 
significant or major based on their potential to emit. In addition, the 
owner or operator of the source shall indicate which, if any, Federal or 
State applicable requirements, emission limitations, or work practices 
apply to each unit.

[[Page 289]]

    (ii) Calculations of the baseline actual emissions (with supporting 
documentation). Baseline actual emissions are to include emissions 
associated not only with operation of the unit, but also emissions 
associated with startup, shutdown, and malfunction.
    (iii) The calculation procedures that the major stationary source 
owner or operator proposes to use to convert the monitoring system data 
to monthly emissions and annual emissions based on a 12-month rolling 
total for each month as required by paragraph (w)(13)(i) of this 
section.
    (4) General requirements for establishing PALs. (i) The plan allows 
the reviewing authority to establish a PAL at a major stationary source, 
provided that at a minimum, the requirements in paragraphs (w)(4)(i)(a) 
through (g) of this section are met.
    (a) The PAL shall impose an annual emission limitation in tons per 
year, that is enforceable as a practical matter, for the entire major 
stationary source. For each month during the PAL effective period after 
the first 12 months of establishing a PAL, the major stationary source 
owner or operator shall show that the sum of the monthly emissions from 
each emissions unit under the PAL for the previous 12 consecutive months 
is less than the PAL (a 12-month average, rolled monthly). For each 
month during the first 11 months from the PAL effective date, the major 
stationary source owner or operator shall show that the sum of the 
preceding monthly emissions from the PAL effective date for each 
emissions unit under the PAL is less than the PAL.
    (b) The PAL shall be established in a PAL permit that meets the 
public participation requirements in paragraph (w)(5) of this section.
    (c) The PAL permit shall contain all the requirements of paragraph 
(w)(7) of this section.
    (d) The PAL shall include fugitive emissions, to the extent 
quantifiable, from all emissions units that emit or have the potential 
to emit the PAL pollutant at the major stationary source.
    (e) Each PAL shall regulate emissions of only one pollutant.
    (f) Each PAL shall have a PAL effective period of 10 years.
    (g) The owner or operator of the major stationary source with a PAL 
shall comply with the monitoring, recordkeeping, and reporting 
requirements provided in paragraphs (w)(12) through (14) of this section 
for each emissions unit under the PAL through the PAL effective period.
    (ii) At no time (during or after the PAL effective period) are 
emissions reductions of a PAL pollutant that occur during the PAL 
effective period creditable as decreases for purposes of offsets under 
Sec. 51.165(a)(3)(ii) of this chapter unless the level of the PAL is 
reduced by the amount of such emissions reductions and such reductions 
would be creditable in the absence of the PAL.
    (5) Public participation requirements for PALs. PALs for existing 
major stationary sources shall be established, renewed, or increased, 
through a procedure that is consistent with Sec. Sec. 51.160 and 51.161 
of this chapter. This includes the requirement that the reviewing 
authority provide the public with notice of the proposed approval of a 
PAL permit and at least a 30-day period for submittal of public comment. 
The reviewing authority must address all material comments before taking 
final action on the permit.
    (6) Setting the 10-year actuals PAL level. (i) Except as provided in 
paragraph (w)(6)(ii) of this section, the plan shall provide that the 
actuals PAL level for a major stationary source shall be established as 
the sum of the baseline actual emissions (as defined in paragraph 
(b)(47) of this section) of the PAL pollutant for each emissions unit at 
the source; plus an amount equal to the applicable significant level for 
the PAL pollutant under paragraph (b)(23) of this section or under the 
Act, whichever is lower. When establishing the actuals PAL level, for a 
PAL pollutant, only one consecutive 24-month period must be used to 
determine the baseline actual emissions for all existing emissions 
units. However, a different consecutive 24-month period may be used for 
each different PAL pollutant. Emissions associated with units that were 
permanently shut down after this 24-month period must be subtracted from

[[Page 290]]

the PAL level. The reviewing authority shall specify a reduced PAL 
level(s) (in tons/yr) in the PAL permit to become effective on the 
future compliance date(s) of any applicable Federal or State regulatory 
requirement(s) that the reviewing authority is aware of prior to 
issuance of the PAL permit. For instance, if the source owner or 
operator will be required to reduce emissions from industrial boilers in 
half from baseline emissions of 60 ppm NOX to a new rule 
limit of 30 ppm, then the permit shall contain a future effective PAL 
level that is equal to the current PAL level reduced by half of the 
original baseline emissions of such unit(s).
    (ii) For newly constructed units (which do not include modifications 
to existing units) on which actual construction began after the 24-month 
period, in lieu of adding the baseline actual emissions as specified in 
paragraph (w)(6)(i) of this section, the emissions must be added to the 
PAL level in an amount equal to the potential to emit of the units.
    (7) Contents of the PAL permit. The plan shall require that the PAL 
permit contain, at a minimum, the information in paragraphs (w)(7)(i) 
through (x) of this section.
    (i) The PAL pollutant and the applicable source-wide emission 
limitation in tons per year.
    (ii) The PAL permit effective date and the expiration date of the 
PAL (PAL effective period).
    (iii) Specification in the PAL permit that if a major stationary 
source owner or operator applies to renew a PAL in accordance with 
paragraph (w)(10) of this section before the end of the PAL effective 
period, then the PAL shall not expire at the end of the PAL effective 
period. It shall remain in effect until a revised PAL permit is issued 
by the reviewing authority.
    (iv) A requirement that emission calculations for compliance 
purposes include emissions from startups, shutdowns and malfunctions.
    (v) A requirement that, once the PAL expires, the major stationary 
source is subject to the requirements of paragraph (w)(9) of this 
section.
    (vi) The calculation procedures that the major stationary source 
owner or operator shall use to convert the monitoring system data to 
monthly emissions and annual emissions based on a 12-month rolling total 
for each month as required by paragraph (w)(3)(i) of this section.
    (vii) A requirement that the major stationary source owner or 
operator monitor all emissions units in accordance with the provisions 
under paragraph (w)(13) of this section.
    (viii) A requirement to retain the records required under paragraph 
(w)(13) of this section on site. Such records may be retained in an 
electronic format.
    (ix) A requirement to submit the reports required under paragraph 
(w)(14) of this section by the required deadlines.
    (x) Any other requirements that the reviewing authority deems 
necessary to implement and enforce the PAL.
    (8) PAL effective period and reopening of the PAL permit. The plan 
shall require the information in paragraphs (w)(8)(i) and (ii) of this 
section.
    (i) PAL effective period. The reviewing authority shall specify a 
PAL effective period of 10 years.
    (ii) Reopening of the PAL permit. (a) During the PAL effective 
period, the plan shall require the reviewing authority to reopen the PAL 
permit to:
    (1) Correct typographical/calculation errors made in setting the PAL 
or reflect a more accurate determination of emissions used to establish 
the PAL;
    (2) Reduce the PAL if the owner or operator of the major stationary 
source creates creditable emissions reductions for use as offsets under 
Sec. 51.165(a)(3)(ii) of this chapter; and
    (3) Revise the PAL to reflect an increase in the PAL as provided 
under paragraph (w)(11) of this section.
    (b) The plan shall provide the reviewing authority discretion to 
reopen the PAL permit for the following:
    (1) Reduce the PAL to reflect newly applicable Federal requirements 
(for example, NSPS) with compliance dates after the PAL effective date;
    (2) Reduce the PAL consistent with any other requirement, that is 
enforceable as a practical matter, and that the State may impose on the 
major stationary source under the plan; and
    (3) Reduce the PAL if the reviewing authority determines that a 
reduction

[[Page 291]]

is necessary to avoid causing or contributing to a NAAQS or PSD 
increment violation, or to an adverse impact on an AQRV that has been 
identified for a Federal Class I area by a Federal Land Manager and for 
which information is available to the general public.
    (c) Except for the permit reopening in paragraph (w)(8)(ii)(a)(1) of 
this section for the correction of typographical/calculation errors that 
do not increase the PAL level, all reopenings shall be carried out in 
accordance with the public participation requirements of paragraph 
(w)(5) of this section.
    (9) Expiration of a PAL. Any PAL that is not renewed in accordance 
with the procedures in paragraph (w)(10) of this section shall expire at 
the end of the PAL effective period, and the requirements in paragraphs 
(w)(9)(i) through (v) of this section shall apply.
    (i) Each emissions unit (or each group of emissions units) that 
existed under the PAL shall comply with an allowable emission limitation 
under a revised permit established according to the procedures in 
paragraphs (w)(9)(i)(a) and (b) of this section.
    (a) Within the time frame specified for PAL renewals in paragraph 
(w)(10)(ii) of this section, the major stationary source shall submit a 
proposed allowable emission limitation for each emissions unit (or each 
group of emissions units, if such a distribution is more appropriate as 
decided by the reviewing authority) by distributing the PAL allowable 
emissions for the major stationary source among each of the emissions 
units that existed under the PAL. If the PAL had not yet been adjusted 
for an applicable requirement that became effective during the PAL 
effective period, as required under paragraph (w)(10)(v) of this 
section, such distribution shall be made as if the PAL had been 
adjusted.
    (b) The reviewing authority shall decide whether and how the PAL 
allowable emissions will be distributed and issue a revised permit 
incorporating allowable limits for each emissions unit, or each group of 
emissions units, as the reviewing authority determines is appropriate.
    (ii) Each emissions unit(s) shall comply with the allowable emission 
limitation on a 12-month rolling basis. The reviewing authority may 
approve the use of monitoring systems (source testing,emission factors, 
etc.) other than CEMS, CERMS, PEMS or CPMS to demonstrate compliance 
with the allowable emission limitation.
    (iii) Until the reviewing authority issues the revised permit 
incorporating allowable limits for each emissions unit, or each group of 
emissions units, as required under paragraph (w)(9)(i)(b) of this 
section, the source shall continue to comply with a source-wide, multi-
unit emissions cap equivalent to the level of the PAL emission 
limitation.
    (iv) Any physical change or change in the method of operation at the 
major stationary source will be subject to major NSR requirements if 
such change meets the definition of major modification in paragraph 
(b)(2) of this section.
    (v) The major stationary source owner or operator shall continue to 
comply with any State or Federal applicable requirements (BACT, RACT, 
NSPS, etc.) that may have applied either during the PAL effective period 
or prior to the PAL effective period except for those emission 
limitations that had been established pursuant to paragraph (r)(2) of 
this section, but were eliminated by the PAL in accordance with the 
provisions in paragraph (w)(1)(ii)(c) of this section.
    (10) Renewal of a PAL. (i) The reviewing authority shall follow the 
procedures specified in paragraph (w)(5) of this section in approving 
any request to renew a PAL for a major stationary source, and shall 
provide both the proposed PAL level and a written rationale for the 
proposed PAL level to the public for review and comment. During such 
public review, any person may propose a PAL level for the source for 
consideration by the reviewing authority.
    (ii) Application deadline. The plan shall require that a major 
stationary source owner or operator shall submit a timely application to 
the reviewing authority to request renewal of a PAL. A timely 
application is one that is submitted at least 6 months prior to, but not 
earlier than 18 months from, the

[[Page 292]]

date of permit expiration. This deadline for application submittal is to 
ensure that the permit will not expire before the permit is renewed. If 
the owner or operator of a major stationary source submits a complete 
application to renew the PAL within this time period, then the PAL shall 
continue to be effective until the revised permit with the renewed PAL 
is issued.
    (iii) Application requirements. The application to renew a PAL 
permit shall contain the information required in paragraphs (w)(10)(iii) 
(a) through (d) of this section.
    (a) The information required in paragraphs (w)(3)(i) through (iii) 
of this section.
    (b) A proposed PAL level.
    (c) The sum of the potential to emit of all emissions units under 
the PAL (with supporting documentation).
    (d) Any other information the owner or operator wishes the reviewing 
authority to consider in determining the appropriate level for renewing 
the PAL.
    (iv) PAL adjustment. In determining whether and how to adjust the 
PAL, the reviewing authority shall consider the options outlined in 
paragraphs (w)(10)(iv) (a) and (b) of this section. However, in no case 
may any such adjustment fail to comply with paragraph (w)(10)(iv)(c) of 
this section.
    (a) If the emissions level calculated in accordance with paragraph 
(w)(6) of this section is equal to or greater than 80 percent of the PAL 
level, the reviewing authority may renew the PAL at the same level 
without considering the factors set forth in paragraph (w)(10)(iv)(b) of 
this section; or
    (b) The reviewing authority may set the PAL at a level that it 
determines to be more representative of the source's baseline actual 
emissions, or that it determines to be appropriate considering air 
quality needs, advances in control technology, anticipated economic 
growth in the area, desire to reward or encourage the source's voluntary 
emissions reductions, or other factors as specifically identified by the 
reviewing authority in its written rationale.
    (c) Notwithstanding paragraphs (w)(10)(iv) (a) and (b) of this 
section:
    (1) If the potential to emit of the major stationary source is less 
than the PAL, the reviewing authority shall adjust the PAL to a level no 
greater than the potential to emit of the source; and
    (2) The reviewing authority shall not approve a renewed PAL level 
higher than the current PAL, unless the major stationary source has 
complied with the provisions of paragraph (w)(11) of this section 
(increasing a PAL).
    (v) If the compliance date for a State or Federal requirement that 
applies to the PAL source occurs during the PAL effective period, and if 
the reviewing authority has not already adjusted for such requirement, 
the PAL shall be adjusted at the time of PAL permit renewal or title V 
permit renewal, whichever occurs first.
    (11) Increasing a PAL during the PAL effective period. (i) The plan 
shall require that the reviewing authority may increase a PAL emission 
limitation only if the major stationary source complies with the 
provisions in paragraphs (w)(11)(i) (a) through (d) of this section.
    (a) The owner or operator of the major stationary source shall 
submit a complete application to request an increase in the PAL limit 
for a PAL major modification. Such application shall identify the 
emissions unit(s) contributing to the increase in emissions so as to 
cause the major stationary source's emissions to equal or exceed its 
PAL.
    (b) As part of this application, the major stationary source owner 
or operator shall demonstrate that the sum of the baseline actual 
emissions of the small emissions units, plus the sum of the baseline 
actual emissions of the significant and major emissions units assuming 
application of BACT equivalent controls, plus the sum of the allowable 
emissions of the new or modified emissions unit(s), exceeds the PAL. The 
level of control that would result from BACT equivalent controls on each 
significant or major emissions unit shall be determined by conducting a 
new BACT analysis at the time the application is submitted, unless the 
emissions unit is currently required to comply with a BACT or LAER 
requirement that was established within the

[[Page 293]]

preceding 10 years. In such a case, the assumed control level for that 
emissions unit shall be equal to the level of BACT or LAER with which 
that emissions unit must currently comply.
    (c) The owner or operator obtains a major NSR permit for all 
emissions unit(s) identified in paragraph (w)(11)(i)(a) of this section, 
regardless of the magnitude of the emissions increase resulting from 
them (that is, no significant levels apply). These emissions unit(s) 
shall comply with any emissions requirements resulting from the major 
NSR process (for example, BACT), even though they have also become 
subject to the PAL or continue to be subject to the PAL.
    (d) The PAL permit shall require that the increased PAL level shall 
be effective on the day any emissions unit that is part of the PAL major 
modification becomes operational and begins to emit the PAL pollutant.
    (ii) The reviewing authority shall calculate the new PAL as the sum 
of the allowable emissions for each modified or new emissions unit, plus 
the sum of the baseline actual emissions of the significant and major 
emissions units (assuming application of BACT equivalent controls as 
determined in accordance with paragraph (w)(11)(i)(b) of this section), 
plus the sum of the baseline actual emissions of the small emissions 
units.
    (iii) The PAL permit shall be revised to reflect the increased PAL 
level pursuant to the public notice requirements of paragraph (w)(5) of 
this section.
    (12) Monitoring requirements for PALs--(i) General requirements. (a) 
Each PAL permit must contain enforceable requirements for the monitoring 
system that accurately determines plantwide emissions of the PAL 
pollutant in terms of mass per unit of time. Any monitoring system 
authorized for use in the PAL permit must be based on sound science and 
meet generally acceptable scientific procedures for data quality and 
manipulation. Additionally, the information generated by such system 
must meet minimum legal requirements for admissibility in a judicial 
proceeding to enforce the PAL permit.
    (b) The PAL monitoring system must employ one or more of the four 
general monitoring approaches meeting the minimum requirements set forth 
in paragraphs (w)(12)(ii) (a) through (d) of this section and must be 
approved by the reviewing authority.
    (c) Notwithstanding paragraph (w)(12)(i)(b) of this section, you may 
also employ an alternative monitoring approach that meets paragraph 
(w)(12)(i)(a) of this section if approved by the reviewing authority.
    (d) Failure to use a monitoring system that meets the requirements 
of this section renders the PAL invalid.
    (ii) Minimum performance requirements for approved monitoring 
approaches. The following are acceptable general monitoring approaches 
when conducted in accordance with the minimum requirements in paragraphs 
(w)(12)(iii) through (ix) of this section:
    (a) Mass balance calculations for activities using coatings or 
solvents;
    (b) CEMS;
    (c) CPMS or PEMS; and
    (d) Emission factors.
    (iii) Mass balance calculations. An owner or operator using mass 
balance calculations to monitor PAL pollutant emissions from activities 
using coating or solvents shall meet the following requirements:
    (a) Provide a demonstrated means of validating the published content 
of the PAL pollutant that is contained in or created by all materials 
used in or at the emissions unit;
    (b) Assume that the emissions unit emits all of the PAL pollutant 
that is contained in or created by any raw material or fuel used in or 
at the emissions unit, if it cannot otherwise be accounted for in the 
process; and
    (c) Where the vendor of a material or fuel, which is used in or at 
the emissions unit, publishes a range of pollutant content from such 
material, the owner or operator must use the highest value of the range 
to calculate the PAL pollutant emissions unless the reviewing authority 
determines there is site-specific data or a site-specific monitoring 
program to support another content within the range.
    (iv) CEMS. An owner or operator using CEMS to monitor PAL pollutant

[[Page 294]]

emissions shall meet the following requirements:
    (a) CEMS must comply with applicable Performance Specifications 
found in 40 CFR part 60, appendix B; and
    (b) CEMS must sample, analyze, and record data at least every 15 
minutes while the emissions unit is operating.
    (v) CPMS or PEMS. An owner or operator using CPMS or PEMS to monitor 
PAL pollutant emissions shall meet the following requirements:
    (a) The CPMS or the PEMS must be based on current site-specific data 
demonstrating a correlation between the monitored parameter(s) and the 
PAL pollutant emissions across the range of operation of the emissions 
unit; and
    (b) Each CPMS or PEMS must sample, analyze, and record data at least 
every 15 minutes, or at another less frequent interval approved by the 
reviewing authority, while the emissions unit is operating.
    (vi) Emission factors. An owner or operator using emission factors 
to monitor PAL pollutant emissions shall meet the following 
requirements:
    (a) All emission factors shall be adjusted, if appropriate, to 
account for the degree of uncertainty or limitations in the factors' 
development;
    (b) The emissions unit shall operate within the designated range of 
use for the emission factor, if applicable; and
    (c) If technically practicable, the owner or operator of a 
significant emissions unit that relies on an emission factor to 
calculate PAL pollutant emissions shall conduct validation testing to 
determine a site-specific emission factor within 6 months of PAL permit 
issuance, unless the reviewing authority determines that testing is not 
required.
    (vii) A source owner or operator must record and report maximum 
potential emissions without considering enforceable emission limitations 
or operational restrictions for an emissions unit during any period of 
time that there is no monitoring data, unless another method for 
determining emissions during such periods is specified in the PAL 
permit.
    (viii) Notwithstanding the requirements in paragraphs (w)(12)(iii) 
through (vii) of this section, where an owner or operator of an 
emissions unit cannot demonstrate a correlation between the monitored 
parameter(s) and the PAL pollutant emissions rate at all operating 
points of the emissions unit, the reviewing authority shall, at the time 
of permit issuance:
    (a) Establish default value(s) for determining compliance with the 
PAL based on the highest potential emissions reasonably estimated at 
such operating point(s); or
    (b) Determine that operation of the emissions unit during operating 
conditions when there is no correlation between monitored parameter(s) 
and the PAL pollutant emissions is a violation of the PAL.
    (ix) Re-validation. All data used to establish the PAL pollutant 
must be re-validated through performance testing or other scientifically 
valid means approved by the reviewing authority. Such testing must occur 
at least once every 5 years after issuance of the PAL.
    (13) Recordkeeping requirements. (i) The PAL permit shall require an 
owner or operator to retain a copy of all records necessary to determine 
compliance with any requirement of paragraph (w) of this section and of 
the PAL, including a determination of each emissions unit's 12-month 
rolling total emissions, for 5 years from the date of such record.
    (ii) The PAL permit shall require an owner or operator to retain a 
copy of the following records, for the duration of the PAL effective 
period plus 5 years:
    (a) A copy of the PAL permit application and any applications for 
revisions to the PAL; and
    (b) Each annual certification of compliance pursuant to title V and 
the data relied on in certifying the compliance.
    (14) Reporting and notification requirements. The owner or operator 
shall submit semi-annual monitoring reports and prompt deviation reports 
to the reviewing authority in accordance with the applicable title V 
operating permit program. The reports shall meet the requirements in 
paragraphs (w)(14)(i) through (iii) of this section.
    (i) Semi-annual report. The semi-annual report shall be submitted to 
the

[[Page 295]]

reviewing authority within 30 days of the end of each reporting period. 
This report shall contain the information required in paragraphs 
(w)(14)(i)(a) through (g) of this section.
    (a) The identification of owner and operator and the permit number.
    (b) Total annual emissions (tons/year) based on a 12-month rolling 
total for each month in the reporting period recorded pursuant to 
paragraph (w)(13)(i) of this section.
    (c) All data relied upon, including, but not limited to, any Quality 
Assurance or Quality Control data, in calculating the monthly and annual 
PAL pollutant emissions.
    (d) A list of any emissions units modified or added to the major 
stationary source during the preceding 6-month period.
    (e) The number, duration, and cause of any deviations or monitoring 
malfunctions (other than the time associated with zero and span 
calibration checks), and any corrective action taken.
    (f) A notification of a shutdown of any monitoring system, whether 
the shutdown was permanent or temporary, the reason for the shutdown, 
the anticipated date that the monitoring system will be fully 
operational or replaced with another monitoring system, and whether the 
emissions unit monitored by the monitoring system continued to operate, 
and the calculation of the emissions of the pollutant or the number 
determined by method included in the permit, as provided by paragraph 
(w)(12)(vii) of this section.
    (g) A signed statement by the responsible official (as defined by 
the applicable title V operating permit program) certifying the truth, 
accuracy, and completeness of the information provided in the report.
    (ii) Deviation report. The major stationary source owner or operator 
shall promptly submit reports of any deviations or exceedance of the PAL 
requirements, including periods where no monitoring is available. A 
report submitted pursuant to Sec. 70.6(a)(3)(iii)(B) of this chapter 
shall satisfy this reporting requirement. The deviation reports shall be 
submitted within the time limits prescribed by the applicable program 
implementing Sec. 70.6(a)(3)(iii)(B) of this chapter. The reports shall 
contain the following information:
    (a) The identification of owner and operator and the permit number;
    (b) The PAL requirement that experienced the deviation or that was 
exceeded;
    (c) Emissions resulting from the deviation or the exceedance; and
    (d) A signed statement by the responsible official (as defined by 
the applicable title V operating permit program) certifying the truth, 
accuracy, and completeness of the information provided in the report.
    (iii) Re-validation results. The owner or operator shall submit to 
the reviewing authority the results of any re-validation test or method 
within three months after completion of such test or method.
    (15) Transition requirements. (i) No reviewing authority may issue a 
PAL that does not comply with the requirements in paragraphs (w)(1) 
through (15) of this section after the Administrator has approved 
regulations incorporating these requirements into a plan.
    (ii) The reviewing authority may supersede any PAL which was 
established prior to the date of approval of the plan by the 
Administrator with a PAL that complies with the requirements of 
paragraphs (w)(1) through (15) of this section.
    (x) If any provision of this section, or the application of such 
provision to any person or circumstance, is held invalid, the remainder 
of this section, or the application of such provision to persons or 
circumstances other than those as to which it is held invalid, shall not 
be affected thereby.
    (y) Equipment replacement provision. Without regard to other 
considerations, routine maintenance, repair and replacement includes, 
but is not limited to, the replacement of any component of a process 
unit with an identical or functionally equivalent component(s), and 
maintenance and repair activities that are part of the replacement 
activity, provided that all of the requirements in paragraphs (y)(1) 
through (3) of this section are met.
    (1) Capital Cost threshold for Equipment Replacement. (i) For an 
electric utility steam generating unit, as defined in

[[Page 296]]

Sec. 51.166(b)(30), the fixed capital cost of the replacement 
component(s) plus the cost of any associated maintenance and repair 
activities that are part of the replacement shall not exceed 20 percent 
of the replacement value of the process unit, at the time the equipment 
is replaced. For a process unit that is not an electric utility steam 
generating unit the fixed capital cost of the replacement component(s) 
plus the cost of any associated maintenance and repair activities that 
are part of the replacement shall not exceed 20 percent of the 
replacement value of the process unit, at the time the equipment is 
replaced.
    (ii) In determining the replacement value of the process unit; and, 
except as otherwise allowed under paragraph (y)(1)(iii) of this section, 
the owner or operator shall determine the replacement value of the 
process unit on an estimate of the fixed capital cost of constructing a 
new process unit, or on the current appraised value of the process unit.
    (iii) As an alternative to paragraph (y)(1)(ii) of this section for 
determining the replacement value of a process unit, an owner or 
operator may choose to use insurance value (where the insurance value 
covers only complete replacement), investment value adjusted for 
inflation, or another accounting procedure if such procedure is based on 
Generally Accepted Accounting Principles, provided that the owner or 
operator sends a notice to the reviewing authority. The first time that 
an owner or operator submits such a notice for a particular process 
unit, the notice may be submitted at any time, but any subsequent notice 
for that process unit may be submitted only at the beginning of the 
process unit's fiscal year. Unless the owner or operator submits a 
notice to the reviewing authority, then paragraph (y)(1)(ii) of this 
section will be used to establish the replacement value of the process 
unit. Once the owner or operator submits a notice to use an alternative 
accounting procedure, the owner or operator must continue to use that 
procedure for the entire fiscal year for that process unit. In 
subsequent fiscal years, the owner or operator must continue to use this 
selected procedure unless and until the owner or operator sends another 
notice to the reviewing authority selecting another procedure consistent 
with this paragraph or paragraph (y)(1)(ii) of this section at the 
beginning of such fiscal year.
    (2) Basic design parameters. The replacement does not change the 
basic design parameter(s) of the process unit to which the activity 
pertains.
    (i) Except as provided in paragraph (y)(2)(iii) of this section, for 
a process unit at a steam electric generating facility, the owner or 
operator may select as its basic design parameters either maximum hourly 
heat input and maximum hourly fuel consumption rate or maximum hourly 
electric output rate and maximum steam flow rate. When establishing fuel 
consumption specifications in terms of weight or volume, the minimum 
fuel quality based on British Thermal Units content shall be used for 
determining the basic design parameter(s) for a coal-fired electric 
utility steam generating unit.
    (ii) Except as provided in paragraph (y)(2)(iii) of this section, 
the basic design parameter(s) for any process unit that is not at a 
steam electric generating facility are maximum rate of fuel or heat 
input, maximum rate of material input, or maximum rate of product 
output. Combustion process units will typically use maximum rate of fuel 
input. For sources having multiple end products and raw materials, the 
owner or operator should consider the primary product or primary raw 
material when selecting a basic design parameter.
    (iii) If the owner or operator believes the basic design 
parameter(s) in paragraphs (y)(2)(i) and (ii) of this section is not 
appropriate for a specific industry or type of process unit, the owner 
or operator may propose to the reviewing authority an alternative basic 
design parameter(s) for the source's process unit(s). If the reviewing 
authority approves of the use of an alternative basic design 
parameter(s), the reviewing authority shall issue a permit that is 
legally enforceable that records such basic design parameter(s) and 
requires the owner or operator to comply with such parameter(s).

[[Page 297]]

    (iv) The owner or operator shall use credible information, such as 
results of historic maximum capability tests, design information from 
the manufacturer, or engineering calculations, in establishing the 
magnitude of the basic design parameter(s) specified in paragraphs 
(y)(2)(i) and (ii) of this section.
    (v) If design information is not available for a process unit, then 
the owner or operator shall determine the process unit's basic design 
parameter(s) using the maximum value achieved by the process unit in the 
five-year period immediately preceding the planned activity.
    (vi) Efficiency of a process unit is not a basic design parameter.
    (3) The replacement activity shall not cause the process unit to 
exceed any emission limitation, or operational limitation that has the 
effect of constraining emissions, that applies to the process unit and 
that is legally enforceable.

    Note to paragraph (y): By a court order on December 24, 2003, this 
paragraph (y) is stayed indefinitely. The stayed provisions will become 
effective immediately if the court terminates the stay. At that time, 
EPA will publish a document in the Federal Register advising the public 
of the termination of the stay.

(Secs. 101(b)(1), 110, 160-169, 171-178, and 301(a), Clean Air Act, as 
amended (42 U.S.C. 7401(b)(1), 7410, 7470-7479, 7501-7508, and 7601(a)); 
sec. 129(a), Clean Air Act Amendments of 1977 (Pub. L. 95-95, 91 Stat. 
685 (Aug. 7, 1977)))

[43 FR 26382, June 19, 1978]

    Editorial Note: For Federal Register citations affecting Sec. 
51.166, see the List of CFR Sections Affected, which appears in the 
Finding Aids section of the printed volume and at www.govinfo.gov.

    Effective Date Note: At 76 FR 17553, Mar. 30, 2011, Sec. 51.166 
paragraphs (b)(2)(v) and (b)(3)(iii)(d) are stayed indefinitely.



               Subpart J_Ambient Air Quality Surveillance

    Authority: Secs. 110, 301(a), 313, 319, Clean Air Act (42 U.S.C. 
7410, 7601(a), 7613, 7619).



Sec. 51.190  Ambient air quality monitoring requirements.

    The requirements for monitoring ambient air quality for purposes of 
the plan are located in subpart C of part 58 of this chapter.

[44 FR 27569, May 10, 1979]



                      Subpart K_Source Surveillance

    Source: 51 FR 40673, Nov. 7, 1986, unless otherwise noted.



Sec. 51.210  General.

    Each plan must provide for monitoring the status of compliance with 
any rules and regulations that set forth any portion of the control 
strategy. Specifically, the plan must meet the requirements of this 
subpart.



Sec. 51.211  Emission reports and recordkeeping.

    The plan must provide for legally enforceable procedures for 
requiring owners or operators of stationary sources to maintain records 
of and periodically report to the State--
    (a) Information on the nature and amount of emissions from the 
stationary sources; and
    (b) Other information as may be necessary to enable the State to 
determine whether the sources are in compliance with applicable portions 
of the control strategy.



Sec. 51.212  Testing, inspection, enforcement, and complaints.

    The plan must provide for--
    (a) Periodic testing and inspection of stationary sources; and
    (b) Establishment of a system for detecting violations of any rules 
and regulations through the enforcement of appropriate visible emission 
limitations and for investigating complaints.
    (c) Enforceable test methods for each emission limit specified in 
the plan. For the purpose of submitting compliance certifications or 
establishing whether or not a person has violated or is in violation of 
any standard in this part, the plan must not preclude the use, including 
the exclusive use, of any credible evidence or information, relevant to 
whether a source would have been in compliance with applicable 
requirements if the appropriate performance or compliance test or 
procedure had been performed. As an enforceable method, States may use:

[[Page 298]]

    (1) Any of the appropriate methods in appendix M to this part, 
Recommended Test Methods for State Implementation Plans; or
    (2) An alternative method following review and approval of that 
method by the Administrator; or
    (3) Any appropriate method in appendix A to 40 CFR part 60.

[51 FR 40673, Nov. 7, 1986, as amended at 55 FR 14249, Apr. 17, 1990; 62 
FR 8328, Feb. 24, 1997]



Sec. 51.213  Transportation control measures.

    (a) The plan must contain procedures for obtaining and maintaining 
data on actual emissions reductions achieved as a result of implementing 
transportation control measures.
    (b) In the case of measures based on traffic flow changes or 
reductions in vehicle use, the data must include observed changes in 
vehicle miles traveled and average speeds.
    (c) The data must be maintained in such a way as to facilitate 
comparison of the planned and actual efficacy of the transportation 
control measures.

[61 FR 30163, June 14, 1996]



Sec. 51.214  Continuous emission monitoring.

    (a) The plan must contain legally enforceable procedures to--
    (1) Require stationary sources subject to emission standards as part 
of an applicable plan to install, calibrate, maintain, and operate 
equipment for continuously monitoring and recording emissions; and
    (2) Provide other information as specified in appendix P of this 
part.
    (b) The procedures must--
    (1) Identify the types of sources, by source category and capacity, 
that must install the equipment; and
    (2) Identify for each source category the pollutants which must be 
monitored.
    (c) The procedures must, as a minimum, require the types of sources 
set forth in appendix P of this part to meet the applicable requirements 
set forth therein.
    (d)(1) The procedures must contain provisions that require the owner 
or operator of each source subject to continuous emission monitoring and 
recording requirements to maintain a file of all pertinent information 
for at least two years following the date of collection of that 
information.
    (2) The information must include emission measurements, continuous 
monitoring system performance testing measurements, performance 
evaluations, calibration checks, and adjustments and maintenance 
performed on such monitoring systems and other reports and records 
required by appendix P of this part.
    (e) The procedures must require the source owner or operator to 
submit information relating to emissions and operation of the emission 
monitors to the State to the extent described in appendix P at least as 
frequently as described therein.
    (f)(1) The procedures must provide that sources subject to the 
requirements of paragraph (c) of this section must have installed all 
necessary equipment and shall have begun monitoring and recording within 
18 months after either--
    (i) The approval of a State plan requiring monitoring for that 
source; or
    (ii) Promulgation by the Agency of monitoring requirements for that 
source.
    (2) The State may grant reasonable extensions of this period to 
sources that--
    (i) Have made good faith efforts to purchases, install, and begin 
the monitoring and recording of emission data; and
    (ii) Have been unable to complete the installation within the 
period.



                        Subpart L_Legal Authority

    Source: 51 FR 40673, Nov. 7, 1986, unless otherwise noted.



Sec. 51.230  Requirements for all plans.

    Each plan must show that the State has legal authority to carry out 
the plan, including authority to:
    (a) Adopt emission standards and limitations and any other measures 
necessary for attainment and maintenance of national standards.
    (b) Enforce applicable laws, regulations, and standards, and seek 
injunctive relief.

[[Page 299]]

    (c) Abate pollutant emissions on an emergency basis to prevent 
substantial endangerment to the health of persons, i.e., authority 
comparable to that available to the Administrator under section 305 of 
the Act.
    (d) Prevent construction, modification, or operation of a facility, 
building, structure, or installation, or combination thereof, which 
directly or indirectly results or may result in emissions of any air 
pollutant at any location which will prevent the attainment or 
maintenance of a national standard.
    (e) Obtain information necessary to determine whether air pollution 
sources are in compliance with applicable laws, regulations, and 
standards, including authority to require recordkeeping and to make 
inspections and conduct tests of air pollution sources.
    (f) Require owners or operators of stationary sources to install, 
maintain, and use emission monitoring devices and to make periodic 
reports to the State on the nature and amounts of emissions from such 
stationary sources; also authority for the State to make such data 
available to the public as reported and as correlated with any 
applicable emission standards or limitations.



Sec. 51.231  Identification of legal authority.

    (a) The provisions of law or regulation which the State determines 
provide the authorities required under this section must be specifically 
identified, and copies of such laws or regulations be submitted with the 
plan.
    (b) The plan must show that the legal authorities specified in this 
subpart are available to the State at the time of submission of the 
plan.
    (c) Legal authority adequate to fulfill the requirements of Sec. 
51.230 (e) and (f) of this subpart may be delegated to the State under 
section 114 of the Act.



Sec. 51.232  Assignment of legal authority to local agencies.

    (a) A State government agency other than the State air pollution 
control agency may be assigned responsibility for carrying out a portion 
of a plan if the plan demonstrates to the Administrator's satisfaction 
that the State governmental agency has the legal authority necessary to 
carry out the portion of plan.
    (b) The State may authorize a local agency to carry out a plan, or 
portion thereof, within such local agency's jurisdiction if--
    (1) The plan demonstrates to the Administrator's satisfaction that 
the local agency has the legal authority necessary to implement the plan 
or portion of it; and
    (2) This authorization does not relieve the State of responsibility 
under the Act for carrying out such plan, or portion thereof.



                Subpart M_Intergovernmental Consultation

    Authority: Secs. 110, 121, 174(a), 301(a), Clean Air Act, as amended 
(42 U.S.C. 7410, 7421, 7504, and 7601(a)).

    Source: 44 FR 35179, June 18, 1979, unless otherwise noted.

                           Agency Designation



Sec. 51.240  General plan requirements.

    Each State implementation plan must identify organizations, by 
official title, that will participate in developing, implementing, and 
enforcing the plan and the responsibilities of such organizations. The 
plan shall include any related agreements or memoranda of understanding 
among the organizations.



Sec. 51.241  Nonattainment areas for carbon monoxide and ozone.

    (a) For each AQCR or portion of an AQCR in which the national 
primary standard for carbon monoxide or ozone will not be attained by 
July 1, 1979, the Governor (or Governors for interstate areas) shall 
certify, after consultation with local officials, the organization 
responsible for developing the revised implementation plan or portions 
thereof for such AQCR.
    (b)-(f) [Reserved]

[44 FR 35179, June 18, 1979, as amended at 48 FR 29302, June 24, 1983; 
60 FR 33922, June 29, 1995; 61 FR 16060, Apr. 11, 1996]

[[Page 300]]



Sec. 51.242  [Reserved]



                     Subpart N_Compliance Schedules

    Source: 51 FR 40673, Nov. 7, 1986, unless otherwise noted.



Sec. 51.260  Legally enforceable compliance schedules.

    (a) Each plan shall contain legally enforceable compliance schedules 
setting forth the dates by which all stationary and mobile sources or 
categories of such sources must be in compliance with any applicable 
requirement of the plan.
    (b) The compliance schedules must contain increments of progress 
required by Sec. 51.262 of this subpart.



Sec. 51.261  Final compliance schedules.

    (a) Unless EPA grants an extension under subpart R, compliance 
schedules designed to provide for attainment of a primary standard 
must--
    (1) Provide for compliance with the applicable plan requirements as 
soon as practicable; or
    (2) Provide for compliance no later than the date specified for 
attainment of the primary standard under;
    (b) Unless EPA grants an extension under subpart R, compliance 
schedules designed to provide for attainment of a secondary standard 
must--
    (1) Provide for compliance with the applicable plan requirements in 
a reasonable time; or
    (2) Provide for compliance no later than the date specified for the 
attainment of the secondary standard under Sec. 51.110(c).



Sec. 51.262  Extension beyond one year.

    (a) Any compliance schedule or revision of it extending over a 
period of more than one year from the date of its adoption by the State 
agency must provide for legally enforceable increments of progress 
toward compliance by each affected source or category of sources. The 
increments of progress must include--
    (1) Each increment of progress specified in Sec. 51.100(q); and
    (2) Additional increments of progress as may be necessary to permit 
close and effective supervision of progress toward timely compliance.
    (b) [Reserved]



            Subpart O_Miscellaneous Plan Content Requirements

    Authority: Secs. 110, 301(a), 313, 319, Clean Air Act (42 U.S.C. 
7410, 7601(a), 7613, 7619).



Sec. 51.280  Resources.

    Each plan must include a description of the resources available to 
the State and local agencies at the date of submission of the plan and 
of any additional resources needed to carry out the plan during the 5-
year period following its submission. The description must include 
projections of the extent to which resources will be acquired at 1-, 3-, 
and 5-year intervals.

[51 FR 40674, Nov. 7, 1986]



Sec. 51.281  Copies of rules and regulations.

    Emission limitations and other measures necessary for attainment and 
maintenance of any national standard, including any measures necessary 
to implement the requirements of subpart L must be adopted as rules and 
regulations enforceable by the State agency. Copies of all such rules 
and regulations must be submitted with the plan. Submittal of a plan 
setting forth proposed rules and regulations will not satisfy the 
requirements of this section nor will it be considered a timely 
submittal.

[51 FR 40674, Nov. 7, 1986]



Sec. 51.285  Public notification.

    By March 1, 1980, the State shall submit a plan revision that 
contains provisions for:
    (a) Notifying the public on a regular basis of instances or areas in 
which any primary standard was exceeded during any portion of the 
preceding calendar year,
    (b) Advising the public of the health hazards associated with such 
an exceedance of a primary standard, and
    (c) Increasing public awareness of:
    (1) Measures which can be taken to prevent a primary standard from 
being exceeded, and

[[Page 301]]

    (2) Ways in which the public can participate in regulatory and other 
efforts to improve air quality.

[44 FR 27569, May 10, 1979]



Sec. 51.286  Electronic reporting.

    States that wish to receive electronic documents must revise the 
State Implementation Plan to satisfy the requirements of 40 CFR Part 3--
(Electronic reporting).

[70 FR 59887, Oct. 13, 2005]



                   Subpart P_Protection of Visibility

    Authority: Secs. 110, 114, 121, 160-169, 169A, and 301 of the Clean 
Air Act, (42 U.S.C. 7410, 7414, 7421, 7470-7479, and 7601).

    Source: 45 FR 80089, Dec. 2, 1980, unless otherwise noted.



Sec. 51.300  Purpose and applicability.

    (a) Purpose. The primary purposes of this subpart are to require 
States to develop programs to assure reasonable progress toward meeting 
the national goal of preventing any future, and remedying any existing, 
impairment of visibility in mandatory Class I Federal areas which 
impairment results from manmade air pollution; and to establish 
necessary additional procedures for new source permit applicants, States 
and Federal Land Managers to use in conducting the visibility impact 
analysis required for new sources under Sec. 51.166. This subpart sets 
forth requirements addressing visibility impairment in its two principal 
forms: ``reasonably attributable'' impairment (i.e., impairment 
attributable to a single source/small group of sources) and regional 
haze (i.e., widespread haze from a multitude of sources which impairs 
visibility in every direction over a large area).
    (b) Applicability The provisions of this subpart are applicable to 
all States as defined in section 302(d) of the Clean Air Act (CAA) 
except Guam, Puerto Rico, American Samoa, and the Northern Mariana 
Islands.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35763, July 1, 1999; 82 
FR 3122, Jan. 10, 2017]



Sec. 51.301  Definitions.

    For purposes of this subpart:
    Adverse impact on visibility means, for purposes of section 307, 
visibility impairment which interferes with the management, protection, 
preservation, or enjoyment of the visitor's visual experience of the 
Federal Class I area. This determination must be made on a case-by-case 
basis taking into account the geographic extent, intensity, duration, 
frequency and time of visibility impairments, and how these factors 
correlate with (1) times of visitor use of the Federal Class I area, and 
(2) the frequency and timing of natural conditions that reduce 
visibility. This term does not include effects on integral vistas.
    Agency means the U.S. Environmental Protection Agency.
    BART-eligible source means an existing stationary facility as 
defined in this section.
    Baseline visibility condition means the average of the five annual 
averages of the individual values of daily visibility for the period 
2000-2004 unique to each Class I area for either the most impaired days 
or the clearest days.
    Best Available Retrofit Technology (BART) means an emission 
limitation based on the degree of reduction achievable through the 
application of the best system of continuous emission reduction for each 
pollutant which is emitted by an existing stationary facility. The 
emission limitation must be established, on a case-by-case basis, taking 
into consideration the technology available, the costs of compliance, 
the energy and nonair quality environmental impacts of compliance, any 
pollution control equipment in use or in existence at the source, the 
remaining useful life of the source, and the degree of improvement in 
visibility which may reasonably be anticipated to result from the use of 
such technology.
    Building, structure, or facility means all of the pollutant-emitting 
activities which belong to the same industrial grouping, are located on 
one or more contiguous or adjacent properties, and are under the control 
of the same person (or persons under common control). Pollutant-emitting 
activities must be

[[Page 302]]

considered as part of the same industrial grouping if they belong to the 
same Major Group (i.e., which have the same two-digit code) as described 
in the Standard Industrial Classification Manual, 1972 as amended by the 
1977 Supplement (U.S. Government Printing Office stock numbers 4101-0066 
and 003-005-00176-0 respectively).
    Clearest days means the twenty percent of monitored days in a 
calendar year with the lowest values of the deciview index.
    Current visibility condition means the average of the five annual 
averages of individual values of daily visibility for the most recent 
period for which data are available unique to each Class I area for 
either the most impaired days or the clearest days.
    Deciview is the unit of measurement on the deciview index scale for 
quantifying in a standard manner human perceptions of visibility.
    Deciview index means a value for a day that is derived from 
calculated or measured light extinction, such that uniform increments of 
the index correspond to uniform incremental changes in perception across 
the entire range of conditions, from pristine to very obscured. The 
deciview index is calculated based on the following equation (for the 
purposes of calculating deciview using IMPROVE data, the atmospheric 
light extinction coefficient must be calculated from aerosol 
measurements and an estimate of Rayleigh scattering):
    Deciview index = 10 ln (bext/10 Mm-1).
    bext = the atmospheric light extinction coefficient, 
expressed in inverse megameters (Mm-1).
    End of the applicable implementation period means December 31 of the 
year in which the next periodic comprehensive implementation plan 
revision is due under Sec. 51.308(f).
    Existing stationary facility means any of the following stationary 
sources of air pollutants, including any reconstructed source, which was 
not in operation prior to August 7, 1962, and was in existence on August 
7, 1977, and has the potential to emit 250 tons per year or more of any 
air pollutant. In determining potential to emit, fugitive emissions, to 
the extent quantifiable, must be counted.
    Fossil-fuel fired steam electric plants of more than 250 million 
British thermal units per hour heat input,
    Coal cleaning plants (thermal dryers),
    Kraft pulp mills,
    Portland cement plants,
    Primary zinc smelters,
    Iron and steel mill plants,
    Primary aluminum ore reduction plants,
    Primary copper smelters,
    Municipal incinerators capable of charging more than 250 tons of 
refuse per day,
    Hydrofluoric, sulfuric, and nitric acid plants,
    Petroleum refineries,
    Lime plants,
    Phosphate rock processing plants,
    Coke oven batteries,
    Sulfur recovery plants,
    Carbon black plants (furnace process),
    Primary lead smelters,
    Fuel conversion plants,
    Sintering plants,
    Secondary metal production facilities,
    Chemical process plants,
    Fossil-fuel boilers of more than 250 million British thermal units 
per hour heat input,
    Petroleum storage and transfer facilities with a capacity exceeding 
300,000 barrels,
    Taconite ore processing facilities,
    Glass fiber processing plants, and
    Charcoal production facilities.
    Federal Class I area means any Federal land that is classified or 
reclassified Class I.
    Federal Land Manager means the Secretary of the department with 
authority over the Federal Class I area (or the Secretary's designee) 
or, with respect to Roosevelt-Campobello International Park, the 
Chairman of the Roosevelt-Campobello International Park Commission.
    Federally enforceable means all limitations and conditions which are 
enforceable by the Administrator under the Clean Air Act including those 
requirements developed pursuant to parts 60 and 61 of this title, 
requirements within any applicable State Implementation Plan, and any 
permit requirements established pursuant to

[[Page 303]]

Sec. 52.21 of this chapter or under regulations approved pursuant to 
part 51, 52, or 60 of this title.
    Fixed capital cost means the capital needed to provide all of the 
depreciable components.
    Fugitive Emissions means those emissions which could not reasonably 
pass through a stack, chimney, vent, or other functionally equivalent 
opening.
    Geographic enhancement for the purpose of Sec. 51.308 means a 
method, procedure, or process to allow a broad regional strategy, such 
as an emissions trading program designed to achieve greater reasonable 
progress than BART for regional haze, to accommodate BART for reasonably 
attributable impairment.
    Implementation plan means, for the purposes of this part, any State 
Implementation Plan, Federal Implementation Plan, or Tribal 
Implementation Plan.
    Indian tribe or tribe means any Indian tribe, band, nation, or other 
organized group or community, including any Alaska Native village, which 
is federally recognized as eligible for the special programs and 
services provided by the United States to Indians because of their 
status as Indians.
    In existence means that the owner or operator has obtained all 
necessary preconstruction approvals or permits required by Federal, 
State, or local air pollution emissions and air quality laws or 
regulations and either has (1) begun, or caused to begin, a continuous 
program of physical on-site construction of the facility or (2) entered 
into binding agreements or contractual obligations, which cannot be 
cancelled or modified without substantial loss to the owner or operator, 
to undertake a program of construction of the facility to be completed 
in a reasonable time.
    In operation means engaged in activity related to the primary design 
function of the source.
    Installation means an identifiable piece of process equipment.
    Integral vista means a view perceived from within the mandatory 
Class I Federal area of a specific landmark or panorama located outside 
the boundary of the mandatory Class I Federal area.
    Least impaired days means the twenty percent of monitored days in a 
calendar year with the lowest amounts of visibility impairment.
    Major stationary source and major modification mean major stationary 
source and major modification, respectively, as defined in Sec. 51.166.
    Mandatory Class I Federal Area or Mandatory Federal Class I Area 
means any area identified in part 81, subpart D of this title.
    Most impaired days means the twenty percent of monitored days in a 
calendar year with the highest amounts of anthropogenic visibility 
impairment.
    Natural conditions reflect naturally occurring phenomena that reduce 
visibility as measured in terms of light extinction, visual range, 
contrast, or coloration, and may refer to the conditions on a single day 
or a set of days. These phenomena include, but are not limited to, 
humidity, fire events, dust storms, volcanic activity, and biogenic 
emissions from soils and trees. These phenomena may be near or far from 
a Class I area and may be outside the United States.
    Natural visibility means visibility (contrast, coloration, and 
texture) on a day or days that would have existed under natural 
conditions. Natural visibility varies with time and location, is 
estimated or inferred rather than directly measured, and may have long-
term trends due to long-term trends in natural conditions.
    Natural visibility condition means the average of individual values 
of daily natural visibility unique to each Class I area for either the 
most impaired days or the clearest days.
    Potential to emit means the maximum capacity of a stationary source 
to emit a pollutant under its physical and operational design. Any 
physical or operational limitation on the capacity of the source to emit 
a pollutant including air pollution control equipment and restrictions 
on hours of operation or on the type or amount of material combusted, 
stored, or processed, shall be treated as part of its design if the 
limitation or the effect it would have on emissions is federally 
enforceable. Secondary emissions do not count in determining the 
potential to emit of a stationary source.

[[Page 304]]

    Prescribed fire means any fire intentionally ignited by management 
actions in accordance with applicable laws, policies, and regulations to 
meet specific land or resource management objectives.
    Reasonably attributable means attributable by visual observation or 
any other appropriate technique.
    Reasonably attributable visibility impairment means visibility 
impairment that is caused by the emission of air pollutants from one, or 
a small number of sources.
    Reconstruction will be presumed to have taken place where the fixed 
capital cost of the new component exceeds 50 percent of the fixed 
capital cost of a comparable entirely new source. Any final decision as 
to whether reconstruction has occurred must be made in accordance with 
the provisions of Sec. 60.15 (f) (1) through (3) of this title.
    Regional haze means visibility impairment that is caused by the 
emission of air pollutants from numerous anthropogenic sources located 
over a wide geographic area. Such sources include, but are not limited 
to, major and minor stationary sources, mobile sources, and area 
sources.
    Secondary emissions means emissions which occur as a result of the 
construction or operation of an existing stationary facility but do not 
come from the existing stationary facility. Secondary emissions may 
include, but are not limited to, emissions from ships or trains coming 
to or from the existing stationary facility.
    Significant impairment means, for purposes of Sec. 51.303, 
visibility impairment which, in the judgment of the Administrator, 
interferes with the management, protection, preservation, or enjoyment 
of the visitor's visual experience of the mandatory Class I Federal 
area. This determination must be made on a case-by-case basis taking 
into account the geographic extent, intensity, duration, frequency and 
time of the visibility impairment, and how these factors correlate with 
(1) times of visitor use of the mandatory Class I Federal area, and (2) 
the frequency and timing of natural conditions that reduce visibility.
    State means ``State'' as defined in section 302(d) of the CAA.
    Stationary Source means any building, structure, facility, or 
installation which emits or may emit any air pollutant.
    Visibility means the degree of perceived clarity when viewing 
objects at a distance. Visibility includes perceived changes in 
contrast, coloration, and texture elements in a scene.
    Visibility impairment or anthropogenic visibility impairment means 
any humanly perceptible difference due to air pollution from 
anthropogenic sources between actual visibility and natural visibility 
on one or more days. Because natural visibility can only be estimated or 
inferred, visibility impairment also is estimated or inferred rather 
than directly measured.
    Visibility in any mandatory Class I Federal area includes any 
integral vista associated with that area.
    Wildfire means any fire started by an unplanned ignition caused by 
lightning; volcanoes; other acts of nature; unauthorized activity; or 
accidental, human-caused actions, or a prescribed fire that has 
developed into a wildfire. A wildfire that predominantly occurs on 
wildland is a natural event.
    Wildland means an area in which human activity and development is 
essentially non-existent, except for roads, railroads, power lines, and 
similar transportation facilities. Structures, if any, are widely 
scattered.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35763, 35774, July 1, 
1999; 82 FR 3122, Jan. 10, 2017]



Sec. 51.302  Reasonably attributable visibility impairment.

    (a) The affected Federal Land Manager may certify, at any time, that 
there exists reasonably attributable visibility impairment in any 
mandatory Class I Federal area and identify which single source or small 
number of sources is responsible for such impairment. The affected 
Federal Land Manager will provide the certification to the State in 
which the impairment occurs and the State(s) in which the source(s) is 
located. The affected Federal Land Manager shall provide the State(s) in 
which the source(s) is located an opportunity to consult on the basis of 
the planned certification, in

[[Page 305]]

person and at least 60 days prior to providing the certification to the 
State(s).
    (b) The State(s) in which the source(s) is located shall revise its 
regional haze implementation plan, in accordance with the schedule set 
forth in paragraph (d) of this section, to include for each source or 
small number of sources that the Federal Land Manager has identified in 
whole or in part for reasonably attributable visibility impairment as 
part of a certification under paragraph (a) of this section:
    (1) A determination, based on the factors set forth in Sec. 
51.308(f)(2), of the control measures, if any, that are necessary with 
respect to the source or sources in order for the plan to make 
reasonable progress toward natural visibility conditions in the affected 
Class I Federal area;
    (2) Emission limitations that reflect the degree of emission 
reduction achievable by such control measures and schedules for 
compliance as expeditiously as practicable; and
    (3) Monitoring, recordkeeping, and reporting requirements sufficient 
to ensure the enforceability of the emission limitations.
    (c) If a source that the Federal Land Manager has identified as 
responsible in whole or in part for reasonably attributable visibility 
impairment as part of a certification under paragraph (a) of this 
section is a BART-eligible source, and if there is not in effect as of 
the date of the certification a fully or conditionally approved 
implementation plan addressing the BART requirement for that source 
(which existing plan may incorporate either source-specific emission 
limitations reflecting the emission control performance of BART, an 
alternative program to address the BART requirement under Sec. 
51.308(e)(2) through (4), or for sources of SO2, a program 
approved under paragraph Sec. 51.309(d)(4)), then the State shall 
revise its regional haze implementation plan to meet the requirements of 
Sec. 51.308(e) with respect to that source, taking into account current 
conditions related to the factors listed in Sec. 51.308(e)(1)(ii)(A). 
This requirement is in addition to the requirement of paragraph (b) of 
this section.
    (d) For any existing reasonably attributable visibility impairment 
the Federal Land Manager certifies to the State(s) under paragraph (a) 
of this section, the State(s) shall submit a revision to its regional 
haze implementation plan that includes the elements described in 
paragraphs (b) and (c) of this section no later than 3 years after the 
date of the certification. The State(s) is not required at that time to 
also revise its reasonable progress goals to reflect any additional 
emission reductions required from the source or sources. In no case 
shall such a revision in response to a reasonably attributable 
visibility impairment certification be due before July 31, 2021.

[82 FR 3123, Jan. 10, 2017]



Sec. 51.303  Exemptions from control.

    (a)(1) Any existing stationary facility subject to the requirement 
under Sec. 51.302(c) or Sec. 51.308(e) to install, operate, and 
maintain BART may apply to the Administrator for an exemption from that 
requirement.
    (2) An application under this section must include all available 
documentation relevant to the impact of the source's emissions on 
visibility in any mandatory Class I Federal area and a demonstration by 
the existing stationary facility that it does not or will not, by itself 
or in combination with other sources, emit any air pollutant which may 
be reasonably anticipated to cause or contribute to a significant 
impairment of visibility in any mandatory Class I Federal area.
    (b) Any fossil-fuel fired power plant with a total generating 
capacity of 750 megawatts or more may receive an exemption from BART 
only if the owner or operator of such power plant demonstrates to the 
satisfaction of the Administrator that such power plant is located at 
such a distance from all mandatory Class I Federal areas that such power 
plant does not or will not, by itself or in combination with other 
sources, emit any air pollutant which may reasonably be anticipated to 
cause or contribute to significant impairment of visibility in any such 
mandatory Class I Federal area.
    (c) Application under this Sec. 51.303 must be accompanied by a 
written concurrence from the State with regulatory authority over the 
source.

[[Page 306]]

    (d) The existing stationary facility must give prior written notice 
to all affected Federal Land Managers of any application for exemption 
under this Sec. 51.303.
    (e) The Federal Land Manager may provide an initial recommendation 
or comment on the disposition of such application. Such recommendation, 
where provided, must be part of the exemption application. This 
recommendation is not to be construed as the concurrence required under 
paragraph (h) of this section.
    (f) The Administrator, within 90 days of receipt of an application 
for exemption from control, will provide notice of receipt of an 
exemption application and notice of opportunity for public hearing on 
the application.
    (g) After notice and opportunity for public hearing, the 
Administrator may grant or deny the exemption. For purposes of judicial 
review, final EPA action on an application for an exemption under this 
Sec. 51.303 will not occur until EPA approves or disapproves the State 
Implementation Plan revision.
    (h) An exemption granted by the Administrator under this Sec. 
51.303 will be effective only upon concurrence by all affected Federal 
Land Managers with the Administrator's determination.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35774, July 1, 1999; 82 
FR 3123, Jan. 10, 2017]



Sec. 51.304  Identification of integral vistas.

    (a) Federal Land Managers were required to identify any integral 
vistas on or before December 31, 1985, according to criteria the Federal 
Land Managers developed. These criteria must have included, but were not 
limited to, whether the integral vista was important to the visitor's 
visual experience of the mandatory Class I Federal area.
    (b) The following integral vistas were identified by Federal Land 
Managers: At Roosevelt Campobello International Park, from the 
observation point of Roosevelt cottage and beach area, the viewing angle 
from 244 to 256 degrees; and at Roosevelt Campobello International Park, 
from the observation point of Friar's Head, the viewing angle from 154 
to 194 degrees.
    (c) The State must list in its implementation plan any integral 
vista listed in paragraph (b) of this section.

[82 FR 3123, Jan. 10, 2017]



Sec. 51.305  Monitoring for reasonably attributable visibility
impairment.

    For the purposes of addressing reasonably attributable visibility 
impairment, if the Administrator, Regional Administrator, or the 
affected Federal Land Manager has advised a State containing a mandatory 
Class I Federal area of a need for monitoring to assess reasonably 
attributable visibility impairment at the mandatory Class I Federal area 
in addition to the monitoring currently being conducted to meet the 
requirements of Sec. 51.308(d)(4), the State must include in the next 
implementation plan revision to meet the requirement of Sec. 51.308(f) 
an appropriate strategy for evaluating reasonably attributable 
visibility impairment in the mandatory Class I Federal area by visual 
observation or other appropriate monitoring techniques. Such strategy 
must take into account current and anticipated visibility monitoring 
research, the availability of appropriate monitoring techniques, and 
such guidance as is provided by the Agency.

[82 FR 3124, Jan. 10, 2017]



Sec. 51.306  [Reserved]



Sec. 51.307  New source review.

    (a) For purposes of new source review of any new major stationary 
source or major modification that would be constructed in an area that 
is designated attainment or unclassified under section 107(d) of the 
CAA, the State plan must, in any review under Sec. 51.166 with respect 
to visibility protection and analyses, provide for:
    (1) Written notification of all affected Federal Land Managers of 
any proposed new major stationary source or major modification that may 
affect visibility in any Federal Class I area. Such notification must be 
made in writing and include a copy of all information relevant to the 
permit application within 30 days of receipt of and at least 60 days 
prior to public hearing by the State on the application for permit to 
construct. Such notification must

[[Page 307]]

include an analysis of the anticipated impacts on visibility in any 
Federal Class I area,
    (2) Where the State requires or receives advance notification (e.g. 
early consultation with the source prior to submission of the 
application or notification of intent to monitor under Sec. 51.166) of 
a permit application of a source that may affect visibility the State 
must notify all affected Federal Land Managers within 30 days of such 
advance notification, and
    (3) Consideration of any analysis performed by the Federal Land 
Manager, provided within 30 days of the notification and analysis 
required by paragraph (a)(1) of this section, that such proposed new 
major stationary source or major modification may have an adverse impact 
on visibility in any Federal Class I area. Where the State finds that 
such an analysis does not demonstrate to the satisfaction of the State 
that an adverse impact will result in the Federal Class I area, the 
State must, in the notice of public hearing, either explain its decision 
or give notice as to where the explanation can be obtained.
    (b) The plan shall also provide for the review of any new major 
stationary source or major modification:
    (1) That may have an impact on any integral vista of a mandatory 
Class I Federal area listed in Sec. 51.304(b), or
    (2) That proposes to locate in an area classified as nonattainment 
under section 107(d)(1) of the Clean Air Act that may have an impact on 
visibility in any mandatory Class I Federal area.
    (c) Review of any major stationary source or major modification 
under paragraph (b) of this section, shall be conducted in accordance 
with paragraph (a) of this section, and Sec. 51.166(o), (p)(1) through 
(2), and (q). In conducting such reviews the State must ensure that the 
source's emissions will be consistent with making reasonable progress 
toward the national visibility goal referred to in Sec. 51.300(a). The 
State may take into account the costs of compliance, the time necessary 
for compliance, the energy and nonair quality environmental impacts of 
compliance, and the useful life of the source.
    (d) The State may require monitoring of visibility in any Federal 
Class I area near the proposed new stationary source or major 
modification for such purposes and by such means as the State deems 
necessary and appropriate.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35765, 35774, July 1, 
1999; 82 FR 3124, Jan. 10, 2017]



Sec. 51.308  Regional haze program requirements.

    (a) What is the purpose of this section? This section establishes 
requirements for implementation plans, plan revisions, and periodic 
progress reviews to address regional haze.
    (b) When are the first implementation plans due under the regional 
haze program? Except as provided in Sec. 51.309(c), each State 
identified in Sec. 51.300(b) must submit, for the entire State, an 
implementation plan for regional haze meeting the requirements of 
paragraphs (d) and (e) of this section no later than December 17, 2007.
    (c) [Reserved]
    (d) What are the core requirements for the implementation plan for 
regional haze? The State must address regional haze in each mandatory 
Class I Federal area located within the State and in each mandatory 
Class I Federal area located outside the State which may be affected by 
emissions from within the State. To meet the core requirements for 
regional haze for these areas, the State must submit an implementation 
plan containing the following plan elements and supporting documentation 
for all required analyses:
    (1) Reasonable progress goals. For each mandatory Class I Federal 
area located within the State, the State must establish goals (expressed 
in deciviews) that provide for reasonable progress towards achieving 
natural visibility conditions. The reasonable progress goals must 
provide for an improvement in visibility for the most impaired days over 
the period of the implementation plan and ensure no degradation in 
visibility for the least impaired days over the same period.
    (i) In establishing a reasonable progress goal for any mandatory 
Class I Federal area within the State, the State must:

[[Page 308]]

    (A) Consider the costs of compliance, the time necessary for 
compliance, the energy and non-air quality environmental impacts of 
compliance, and the remaining useful life of any potentially affected 
sources, and include a demonstration showing how these factors were 
taken into consideration in selecting the goal.
    (B) Analyze and determine the rate of progress needed to attain 
natural visibility conditions by the year 2064. To calculate this rate 
of progress, the State must compare baseline visibility conditions to 
natural visibility conditions in the mandatory Federal Class I area and 
determine the uniform rate of visibility improvement (measured in 
deciviews) that would need to be maintained during each implementation 
period in order to attain natural visibility conditions by 2064. In 
establishing the reasonable progress goal, the State must consider the 
uniform rate of improvement in visibility and the emission reduction 
measures needed to achieve it for the period covered by the 
implementation plan.
    (ii) For the period of the implementation plan, if the State 
establishes a reasonable progress goal that provides for a slower rate 
of improvement in visibility than the rate that would be needed to 
attain natural conditions by 2064, the State must demonstrate, based on 
the factors in paragraph (d)(1)(i)(A) of this section, that the rate of 
progress for the implementation plan to attain natural conditions by 
2064 is not reasonable; and that the progress goal adopted by the State 
is reasonable. The State must provide to the public for review as part 
of its implementation plan an assessment of the number of years it would 
take to attain natural conditions if visibility improvement continues at 
the rate of progress selected by the State as reasonable.
    (iii) In determining whether the State's goal for visibility 
improvement provides for reasonable progress towards natural visibility 
conditions, the Administrator will evaluate the demonstrations developed 
by the State pursuant to paragraphs (d)(1)(i) and (d)(1)(ii) of this 
section.
    (iv) In developing each reasonable progress goal, the State must 
consult with those States which may reasonably be anticipated to cause 
or contribute to visibility impairment in the mandatory Class I Federal 
area. In any situation in which the State cannot agree with another such 
State or group of States that a goal provides for reasonable progress, 
the State must describe in its submittal the actions taken to resolve 
the disagreement. In reviewing the State's implementation plan 
submittal, the Administrator will take this information into account in 
determining whether the State's goal for visibility improvement provides 
for reasonable progress towards natural visibility conditions.
    (v) The reasonable progress goals established by the State are not 
directly enforceable but will be considered by the Administrator in 
evaluating the adequacy of the measures in the implementation plan to 
achieve the progress goal adopted by the State.
    (vi) The State may not adopt a reasonable progress goal that 
represents less visibility improvement than is expected to result from 
implementation of other requirements of the CAA during the applicable 
planning period.
    (2) Calculations of baseline and natural visibility conditions. For 
each mandatory Class I Federal area located within the State, the State 
must determine the following visibility conditions (expressed in 
deciviews):
    (i) Baseline visibility conditions for the most impaired and least 
impaired days. The period for establishing baseline visibility 
conditions is 2000 to 2004. Baseline visibility conditions must be 
calculated, using available monitoring data, by establishing the average 
degree of visibility impairment for the most and least impaired days for 
each calendar year from 2000 to 2004. The baseline visibility conditions 
are the average of these annual values. For mandatory Class I Federal 
areas without onsite monitoring data for 2000-2004, the State must 
establish baseline values using the most representative available 
monitoring data for 2000-2004, in consultation with the Administrator or 
his or her designee;
    (ii) For an implementation plan that is submitted by 2003, the 
period for establishing baseline visibility conditions for the period of 
the first long-

[[Page 309]]

term strategy is the most recent 5-year period for which visibility 
monitoring data are available for the mandatory Class I Federal areas 
addressed by the plan. For mandatory Class I Federal areas without 
onsite monitoring data, the State must establish baseline values using 
the most representative available monitoring data, in consultation with 
the Administrator or his or her designee;
    (iii) Natural visibility conditions for the most impaired and least 
impaired days. Natural visibility conditions must be calculated by 
estimating the degree of visibility impairment existing under natural 
conditions for the most impaired and least impaired days, based on 
available monitoring information and appropriate data analysis 
techniques; and
    (iv) For the first implementation plan addressing the requirements 
of paragraphs (d) and (e) of this section, the number of deciviews by 
which baseline conditions exceed natural visibility conditions for the 
most impaired and least impaired days.
    (3) Long-term strategy for regional haze. Each State listed in Sec. 
51.300(b) must submit a long-term strategy that addresses regional haze 
visibility impairment for each mandatory Class I Federal area within the 
State and for each mandatory Class I Federal area located outside the 
State that may be affected by emissions from the State. The long-term 
strategy must include enforceable emissions limitations, compliance 
schedules, and other measures as necessary to achieve the reasonable 
progress goals established by States having mandatory Class I Federal 
areas. In establishing its long-term strategy for regional haze, the 
State must meet the following requirements:
    (i) Where the State has emissions that are reasonably anticipated to 
contribute to visibility impairment in any mandatory Class I Federal 
area located in another State or States, the State must consult with the 
other State(s) in order to develop coordinated emission management 
strategies. The State must consult with any other State having emissions 
that are reasonably anticipated to contribute to visibility impairment 
in any mandatory Class I Federal area within the State.
    (ii) Where other States cause or contribute to impairment in a 
mandatory Class I Federal area, the State must demonstrate that it has 
included in its implementation plan all measures necessary to obtain its 
share of the emission reductions needed to meet the progress goal for 
the area. If the State has participated in a regional planning process, 
the State must ensure it has included all measures needed to achieve its 
apportionment of emission reduction obligations agreed upon through that 
process.
    (iii) The State must document the technical basis, including 
modeling, monitoring and emissions information, on which the State is 
relying to determine its apportionment of emission reduction obligations 
necessary for achieving reasonable progress in each mandatory Class I 
Federal area it affects. The State may meet this requirement by relying 
on technical analyses developed by the regional planning organization 
and approved by all State participants. The State must identify the 
baseline emissions inventory on which its strategies are based. The 
baseline emissions inventory year is presumed to be the most recent year 
of the consolidate periodic emissions inventory.
    (iv) The State must identify all anthropogenic sources of visibility 
impairment considered by the State in developing its long-term strategy. 
The State should consider major and minor stationary sources, mobile 
sources, and area sources.
    (v) The State must consider, at a minimum, the following factors in 
developing its long-term strategy:
    (A) Emission reductions due to ongoing air pollution control 
programs, including measures to address reasonably attributable 
visibility impairment;
    (B) Measures to mitigate the impacts of construction activities;
    (C) Emissions limitations and schedules for compliance to achieve 
the reasonable progress goal;
    (D) Source retirement and replacement schedules;

[[Page 310]]

    (E) Smoke management techniques for agricultural and forestry 
management purposes including plans as currently exist within the State 
for these purposes;
    (F) Enforceability of emissions limitations and control measures; 
and
    (G) The anticipated net effect on visibility due to projected 
changes in point, area, and mobile source emissions over the period 
addressed by the long-term strategy.
    (4) Monitoring strategy and other implementation plan requirements. 
The State must submit with the implementation plan a monitoring strategy 
for measuring, characterizing, and reporting of regional haze visibility 
impairment that is representative of all mandatory Class I Federal areas 
within the State. This monitoring strategy must be coordinated with the 
monitoring strategy required in Sec. 51.305 for reasonably attributable 
visibility impairment. Compliance with this requirement may be met 
through participation in the Interagency Monitoring of Protected Visual 
Environments network. The implementation plan must also provide for the 
following:
    (i) The establishment of any additional monitoring sites or 
equipment needed to assess whether reasonable progress goals to address 
regional haze for all mandatory Class I Federal areas within the State 
are being achieved.
    (ii) Procedures by which monitoring data and other information are 
used in determining the contribution of emissions from within the State 
to regional haze visibility impairment at mandatory Class I Federal 
areas both within and outside the State.
    (iii) For a State with no mandatory Class I Federal areas, 
procedures by which monitoring data and other information are used in 
determining the contribution of emissions from within the State to 
regional haze visibility impairment at mandatory Class I Federal areas 
in other States.
    (iv) The implementation plan must provide for the reporting of all 
visibility monitoring data to the Administrator at least annually for 
each mandatory Class I Federal area in the State. To the extent 
possible, the State should report visibility monitoring data 
electronically.
    (v) A statewide inventory of emissions of pollutants that are 
reasonably anticipated to cause or contribute to visibility impairment 
in any mandatory Class I Federal area. The inventory must include 
emissions for a baseline year, emissions for the most recent year for 
which data are available, and estimates of future projected emissions. 
The State must also include a commitment to update the inventory 
periodically.
    (vi) Other elements, including reporting, recordkeeping, and other 
measures, necessary to assess and report on visibility.
    (e) Best Available Retrofit Technology (BART) requirements for 
regional haze visibility impairment. The State must submit an 
implementation plan containing emission limitations representing BART 
and schedules for compliance with BART for each BART-eligible source 
that may reasonably be anticipated to cause or contribute to any 
impairment of visibility in any mandatory Class I Federal area, unless 
the State demonstrates that an emissions trading program or other 
alternative will achieve greater reasonable progress toward natural 
visibility conditions.
    (1) To address the requirements for BART, the State must submit an 
implementation plan containing the following plan elements and include 
documentation for all required analyses:
    (i) A list of all BART-eligible sources within the State.
    (ii) A determination of BART for each BART-eligible source in the 
State that emits any air pollutant which may reasonably be anticipated 
to cause or contribute to any impairment of visibility in any mandatory 
Class I Federal area. All such sources are subject to BART.
    (A) The determination of BART must be based on an analysis of the 
best system of continuous emission control technology available and 
associated emission reductions achievable for each BART-eligible source 
that is subject to BART within the State. In this analysis, the State 
must take into consideration the technology available, the costs of 
compliance, the energy and nonair quality environmental impacts of 
compliance, any pollution control

[[Page 311]]

equipment in use at the source, the remaining useful life of the source, 
and the degree of improvement in visibility which may reasonably be 
anticipated to result from the use of such technology.
    (B) The determination of BART for fossil-fuel fired power plants 
having a total generating capacity greater than 750 megawatts must be 
made pursuant to the guidelines in appendix Y of this part (Guidelines 
for BART Determinations Under the Regional Haze Rule).
    (C) Exception.  A State is not required to make a determination of 
BART for SO2 or for NOX if a BART-eligible source 
has the potential to emit less than 40 tons per year of such 
pollutant(s), or for PM10 if a BART-eligible source has the 
potential to emit less than 15 tons per year of such pollutant.
    (iii) If the State determines in establishing BART that 
technological or economic limitations on the applicability of 
measurement methodology to a particular source would make the imposition 
of an emission standard infeasible, it may instead prescribe a design, 
equipment, work practice, or other operational standard, or combination 
thereof, to require the application of BART. Such standard, to the 
degree possible, is to set forth the emission reduction to be achieved 
by implementation of such design, equipment, work practice or operation, 
and must provide for compliance by means which achieve equivalent 
results.
    (iv) A requirement that each source subject to BART be required to 
install and operate BART as expeditiously as practicable, but in no 
event later than 5 years after approval of the implementation plan 
revision.
    (v) A requirement that each source subject to BART maintain the 
control equipment required by this subpart and establish procedures to 
ensure such equipment is properly operated and maintained.
    (2) A State may opt to implement or require participation in an 
emissions trading program or other alternative measure rather than to 
require sources subject to BART to install, operate, and maintain BART. 
Such an emissions trading program or other alternative measure must 
achieve greater reasonable progress than would be achieved through the 
installation and operation of BART. For all such emission trading 
programs or other alternative measures, the State must submit an 
implementation plan containing the following plan elements and include 
documentation for all required analyses:
    (i) A demonstration that the emissions trading program or other 
alternative measure will achieve greater reasonable progress than would 
have resulted from the installation and operation of BART at all sources 
subject to BART in the State and covered by the alternative program. 
This demonstration must be based on the following:
    (A) A list of all BART-eligible sources within the State.
    (B) A list of all BART-eligible sources and all BART source 
categories covered by the alternative program. The State is not required 
to include every BART source category or every BART-eligible source 
within a BART source category in an alternative program, but each BART-
eligible source in the State must be subject to the requirements of the 
alternative program, have a federally enforceable emission limitation 
determined by the State and approved by EPA as meeting BART in 
accordance with section 302(c) or paragraph (e)(1) of this section, or 
otherwise addressed under paragraphs (e)(1) or (e)(4)of this section.
    (C) An analysis of the best system of continuous emission control 
technology available and associated emission reductions achievable for 
each source within the State subject to BART and covered by the 
alternative program. This analysis must be conducted by making a 
determination of BART for each source subject to BART and covered by the 
alternative program as provided for in paragraph (e)(1) of this section, 
unless the emissions trading program or other alternative measure has 
been designed to meet a requirement other than BART (such as the core 
requirement to have a long-term strategy to achieve the reasonable 
progress goals established by States). In this case, the State may 
determine the best system of continuous emission control technology and 
associated emission reductions for similar

[[Page 312]]

types of sources within a source category based on both source-specific 
and category-wide information, as appropriate.
    (D) An analysis of the projected emissions reductions achievable 
through the trading program or other alternative measure.
    (E) A determination under paragraph (e)(3) of this section or 
otherwise based on the clear weight of evidence that the trading program 
or other alternative measure achieves greater reasonable progress than 
would be achieved through the installation and operation of BART at the 
covered sources.
    (ii) [Reserved]
    (iii) A requirement that all necessary emission reductions take 
place during the period of the first long-term strategy for regional 
haze. To meet this requirement, the State must provide a detailed 
description of the emissions trading program or other alternative 
measure, including schedules for implementation, the emission reductions 
required by the program, all necessary administrative and technical 
procedures for implementing the program, rules for accounting and 
monitoring emissions, and procedures for enforcement.
    (iv) A demonstration that the emission reductions resulting from the 
emissions trading program or other alternative measure will be surplus 
to those reductions resulting from measures adopted to meet requirements 
of the CAA as of the baseline date of the SIP.
    (v) At the State's option, a provision that the emissions trading 
program or other alternative measure may include a geographic 
enhancement to the program to address the requirement under Sec. 
51.302(b) or (c) related to reasonably attributable impairment from the 
pollutants covered under the emissions trading program or other 
alternative measure.
    (vi) For plans that include an emissions trading program that 
establishes a cap on total annual emissions of SO2 or 
NOX from sources subject to the program, requires the owners 
and operators of sources to hold allowances or authorizations to emit 
equal to emissions, and allows the owners and operators of sources and 
other entities to purchase, sell, and transfer allowances, the following 
elements are required concerning the emissions covered by the cap:
    (A) Applicability provisions defining the sources subject to the 
program. The State must demonstrate that the applicability provisions 
(including the size criteria for including sources in the program) are 
designed to prevent any significant potential shifting within the State 
of production and emissions from sources in the program to sources 
outside the program. In the case of a program covering sources in 
multiple States, the States must demonstrate that the applicability 
provisions in each State cover essentially the same size facilities and, 
if source categories are specified, cover the same source categories and 
prevent any significant, potential shifting within such States of 
production and emissions to sources outside the program.
    (B) Allowance provisions ensuring that the total value of allowances 
(in tons) issued each year under the program will not exceed the 
emissions cap (in tons) on total annual emissions from the sources in 
the program.
    (C) Monitoring provisions providing for consistent and accurate 
measurements of emissions from sources in the program to ensure that 
each allowance actually represents the same specified tonnage of 
emissions and that emissions are measured with similar accuracy at all 
sources in the program. The monitoring provisions must require that 
boilers, combustion turbines, and cement kilns in the program allowed to 
sell or transfer allowances must comply with the requirements of part 75 
of this chapter. The monitoring provisions must require that other 
sources in the program allowed to sell or transfer allowances must 
provide emissions information with the same precision, reliability, 
accessibility, and timeliness as information provided under part 75 of 
this chapter.
    (D) Recordkeeping provisions that ensure the enforceability of the 
emissions monitoring provisions and other program requirements. The 
recordkeeping provisions must require that boilers, combustion turbines, 
and cement kilns in the program allowed to

[[Page 313]]

sell or transfer allowances must comply with the recordkeeping 
provisions of part 75 of this chapter. The recordkeeping provisions must 
require that other sources in the program allowed to sell or transfer 
allowances must comply with recordkeeping requirements that, as compared 
with the recordkeeping provisions under part 75 of this chapter, are of 
comparable stringency and require recording of comparable types of 
information and retention of the records for comparable periods of time.
    (E) Reporting provisions requiring timely reporting of monitoring 
data with sufficient frequency to ensure the enforceability of the 
emissions monitoring provisions and other program requirements and the 
ability to audit the program. The reporting provisions must require that 
boilers, combustion turbines, and cement kilns in the program allowed to 
sell or transfer allowances must comply with the reporting provisions of 
part 75 of this chapter, except that, if the Administrator is not the 
tracking system administrator for the program, emissions may be reported 
to the tracking system administrator, rather than to the Administrator. 
The reporting provisions must require that other sources in the program 
allowed to sell or transfer allowances must comply with reporting 
requirements that, as compared with the reporting provisions under part 
75 of this chapter, are of comparable stringency and require reporting 
of comparable types of information and require comparable timeliness and 
frequency of reporting.
    (F) Tracking system provisions which provide for a tracking system 
that is publicly available in a secure, centralized database to track in 
a consistent manner all allowances and emissions in the program.
    (G) Authorized account representative provisions ensuring that the 
owners and operators of a source designate one individual who is 
authorized to represent the owners and operators in all matters 
pertaining to the trading program.
    (H) Allowance transfer provisions providing procedures that allow 
timely transfer and recording of allowances, minimize administrative 
barriers to the operation of the allowance market, and ensure that such 
procedures apply uniformly to all sources and other potential 
participants in the allowance market.
    (I) Compliance provisions prohibiting a source from emitting a total 
tonnage of a pollutant that exceeds the tonnage value of its allowance 
holdings, including the methods and procedures for determining whether 
emissions exceed allowance holdings. Such method and procedures shall 
apply consistently from source to source.
    (J) Penalty provisions providing for mandatory allowance deductions 
for excess emissions that apply consistently from source to source. The 
tonnage value of the allowances deducted shall equal at least three 
times the tonnage of the excess emissions.
    (K) For a trading program that allows banking of allowances, 
provisions clarifying any restrictions on the use of these banked 
allowances.
    (L) Program assessment provisions providing for periodic program 
evaluation to assess whether the program is accomplishing its goals and 
whether modifications to the program are needed to enhance performance 
of the program.
    (3) A State which opts under 40 CFR 51.308(e)(2) to implement an 
emissions trading program or other alternative measure rather than to 
require sources subject to BART to install, operate, and maintain BART 
may satisfy the final step of the demonstration required by that section 
as follows: If the distribution of emissions is not substantially 
different than under BART, and the alternative measure results in 
greater emission reductions, then the alternative measure may be deemed 
to achieve greater reasonable progress. If the distribution of emissions 
is significantly different, the State must conduct dispersion modeling 
to determine differences in visibility between BART and the trading 
program for each impacted Class I area, for the worst and best 20 
percent of days. The modeling would demonstrate ``greater reasonable 
progress'' if both of the following two criteria are met:
    (i) Visibility does not decline in any Class I area, and

[[Page 314]]

    (ii) There is an overall improvement in visibility, determined by 
comparing the average differences between BART and the alternative over 
all affected Class I areas.
    (4) A State whose sources are subject to a trading program 
established under part 97 of this chapter in accordance with a federal 
implementation plan set forth in Sec. 52.38 or Sec. 52.39 of this 
chapter or a trading program established under a SIP revision approved 
by the Administrator as meeting the requirements of Sec. 52.38 or Sec. 
52.39 of this chapter need not require BART-eligible fossil fuel-fired 
steam electric plants in the State to install, operate, and maintain 
BART for the pollutant covered by such trading program in the State. A 
State may adopt provisions, consistent with the requirements applicable 
to the State's sources for such trading program, for a geographic 
enhancement to the trading program to address any requirement under 
Sec. 51.302(b) or (c) related to reasonably attributable impairment 
from the pollutant covered by such trading program in that State.
    (5) After a State has met the requirements for BART or implemented 
an emissions trading program or other alternative measure that achieves 
more reasonable progress than the installation and operation of BART, 
BART-eligible sources will be subject to the requirements of paragraphs 
(d) and (f) of this section, as applicable, in the same manner as other 
sources.
    (6) Any BART-eligible facility subject to the requirement under 
paragraph (e) of this section to install, operate, and maintain BART may 
apply to the Administrator for an exemption from that requirement. An 
application for an exemption will be subject to the requirements of 
Sec. 51.303(a)(2)-(h).
    (f) Requirements for periodic comprehensive revisions of 
implementation plans for regional haze. Each State identified in Sec. 
51.300(b) must revise and submit its regional haze implementation plan 
revision to EPA by July 31, 2021, July 31, 2028, and every 10 years 
thereafter. The plan revision due on or before July 31, 2021, must 
include a commitment by the State to meet the requirements of paragraph 
(g) of this section. In each plan revision, the State must address 
regional haze in each mandatory Class I Federal area located within the 
State and in each mandatory Class I Federal area located outside the 
State that may be affected by emissions from within the State. To meet 
the core requirements for regional haze for these areas, the State must 
submit an implementation plan containing the following plan elements and 
supporting documentation for all required analyses:
    (1) Calculations of baseline, current, and natural visibility 
conditions; progress to date; and the uniform rate of progress. For each 
mandatory Class I Federal area located within the State, the State must 
determine the following:
    (i) Baseline visibility conditions for the most impaired and 
clearest days. The period for establishing baseline visibility 
conditions is 2000 to 2004. The State must calculate the baseline 
visibility conditions for the most impaired days and the clearest days 
using available monitoring data. To determine the baseline visibility 
condition, the State must calculate the average of the annual deciview 
index values for the most impaired days and for the clearest days for 
the calendar years from 2000 to 2004. The baseline visibility condition 
for the most impaired days or the clearest days is the average of the 
respective annual values. For purposes of calculating the uniform rate 
of progress, the baseline visibility condition for the most impaired 
days must be associated with the last day of 2004. For mandatory Class I 
Federal areas without onsite monitoring data for 2000-2004, the State 
must establish baseline values using the most representative available 
monitoring data for 2000-2004, in consultation with the Administrator or 
his or her designee. For mandatory Class I Federal areas with incomplete 
monitoring data for 2000-2004, the State must establish baseline values 
using the 5 complete years of monitoring data closest in time to 2000-
2004.
    (ii) Natural visibility conditions for the most impaired and 
clearest days. A State must calculate natural visibility condition by 
estimating the average deciview index existing under natural conditions 
for the most impaired days or the clearest days based on available 
monitoring information and appropriate data analysis techniques; and

[[Page 315]]

    (iii) Current visibility conditions for the most impaired and 
clearest days. The period for calculating current visibility conditions 
is the most recent 5-year period for which data are available. The State 
must calculate the current visibility conditions for the most impaired 
days and the clearest days using available monitoring data. To calculate 
each current visibility condition, the State must calculate the average 
of the annual deciview index values for the years in the most recent 5-
year period. The current visibility condition for the most impaired or 
the clearest days is the average of the respective annual values.
    (iv) Progress to date for the most impaired and clearest days. 
Actual progress made towards the natural visibility condition since the 
baseline period, and actual progress made during the previous 
implementation period up to and including the period for calculating 
current visibility conditions, for the most impaired and for the 
clearest days.
    (v) Differences between current visibility condition and natural 
visibility condition. The number of deciviews by which the current 
visibility condition exceeds the natural visibility condition, for the 
most impaired and for the clearest days.
    (vi) Uniform rate of progress. (A) The uniform rate of progress for 
each mandatory Class I Federal area in the State. To calculate the 
uniform rate of progress, the State must compare the baseline visibility 
condition for the most impaired days to the natural visibility condition 
for the most impaired days in the mandatory Class I Federal area and 
determine the uniform rate of visibility improvement (measured in 
deciviews of improvement per year) that would need to be maintained 
during each implementation period in order to attain natural visibility 
conditions by the end of 2064.
    (B) As part of its implementation plan submission, the State may 
propose (1) an adjustment to the uniform rate of progress for a 
mandatory Class I Federal area to account for impacts from anthropogenic 
sources outside the United States and/or (2) an adjustment to the 
uniform rate of progress for the mandatory Class I Federal area to 
account for impacts from wildland prescribed fires that were conducted 
with the objective to establish, restore, and/or maintain sustainable 
and resilient wildland ecosystems, to reduce the risk of catastrophic 
wildfires, and/or to preserve endangered or threatened species during 
which appropriate basic smoke management practices were applied. To 
calculate the proposed adjustment(s), the State must add the estimated 
impact(s) to the natural visibility condition and compare the baseline 
visibility condition for the most impaired days to the resulting sum. If 
the Administrator determines that the State has estimated the impact(s) 
from anthropogenic sources outside the United States and/or wildland 
prescribed fires using scientifically valid data and methods, the 
Administrator may approve the proposed adjustment(s) to the uniform rate 
of progress.
    (2) Long-term strategy for regional haze. Each State must submit a 
long-term strategy that addresses regional haze visibility impairment 
for each mandatory Class I Federal area within the State and for each 
mandatory Class I Federal area located outside the State that may be 
affected by emissions from the State. The long-term strategy must 
include the enforceable emissions limitations, compliance schedules, and 
other measures that are necessary to make reasonable progress, as 
determined pursuant to (f)(2)(i) through (iv). In establishing its long-
term strategy for regional haze, the State must meet the following 
requirements:
    (i) The State must evaluate and determine the emission reduction 
measures that are necessary to make reasonable progress by considering 
the costs of compliance, the time necessary for compliance, the energy 
and non-air quality environmental impacts of compliance, and the 
remaining useful life of any potentially affected anthropogenic source 
of visibility impairment. The State should consider evaluating major and 
minor stationary sources or groups of sources, mobile sources, and area 
sources. The State must include in its implementation plan a description 
of the criteria it used to determine which sources or groups of sources 
it evaluated and how

[[Page 316]]

the four factors were taken into consideration in selecting the measures 
for inclusion in its long-term strategy. In considering the time 
necessary for compliance, if the State concludes that a control measure 
cannot reasonably be installed and become operational until after the 
end of the implementation period, the State may not consider this fact 
in determining whether the measure is necessary to make reasonable 
progress.
    (ii) The State must consult with those States that have emissions 
that are reasonably anticipated to contribute to visibility impairment 
in the mandatory Class I Federal area to develop coordinated emission 
management strategies containing the emission reductions necessary to 
make reasonable progress.
    (A) The State must demonstrate that it has included in its 
implementation plan all measures agreed to during state-to-state 
consultations or a regional planning process, or measures that will 
provide equivalent visibility improvement.
    (B) The State must consider the emission reduction measures 
identified by other States for their sources as being necessary to make 
reasonable progress in the mandatory Class I Federal area.
    (C) In any situation in which a State cannot agree with another 
State on the emission reduction measures necessary to make reasonable 
progress in a mandatory Class I Federal area, the State must describe 
the actions taken to resolve the disagreement. In reviewing the State's 
implementation plan, the Administrator will take this information into 
account in determining whether the plan provides for reasonable progress 
at each mandatory Class I Federal area that is located in the State or 
that may be affected by emissions from the State. All substantive 
interstate consultations must be documented.
    (iii) The State must document the technical basis, including 
modeling, monitoring, cost, engineering, and emissions information, on 
which the State is relying to determine the emission reduction measures 
that are necessary to make reasonable progress in each mandatory Class I 
Federal area it affects. The State may meet this requirement by relying 
on technical analyses developed by a regional planning process and 
approved by all State participants. The emissions information must 
include, but need not be limited to, information on emissions in a year 
at least as recent as the most recent year for which the State has 
submitted emission inventory information to the Administrator in 
compliance with the triennial reporting requirements of subpart A of 
this part. However, if a State has made a submission for a new inventory 
year to meet the requirements of subpart A in the period 12 months prior 
to submission of the SIP, the State may use the inventory year of its 
prior submission.
    (iv) The State must consider the following additional factors in 
developing its long-term strategy:
    (A) Emission reductions due to ongoing air pollution control 
programs, including measures to address reasonably attributable 
visibility impairment;
    (B) Measures to mitigate the impacts of construction activities;
    (C) Source retirement and replacement schedules;
    (D) Basic smoke management practices for prescribed fire used for 
agricultural and wildland vegetation management purposes and smoke 
management programs; and
    (E) The anticipated net effect on visibility due to projected 
changes in point, area, and mobile source emissions over the period 
addressed by the long-term strategy.
    (3) Reasonable progress goals. (i) A state in which a mandatory 
Class I Federal area is located must establish reasonable progress goals 
(expressed in deciviews) that reflect the visibility conditions that are 
projected to be achieved by the end of the applicable implementation 
period as a result of those enforceable emissions limitations, 
compliance schedules, and other measures required under paragraph (f)(2) 
of this section that can be fully implemented by the end of the 
applicable implementation period, as well as the implementation of other 
requirements of the CAA. The long-term strategy and the reasonable 
progress goals must provide for an improvement in visibility for the 
most impaired days

[[Page 317]]

since the baseline period and ensure no degradation in visibility for 
the clearest days since the baseline period.
    (ii)(A) If a State in which a mandatory Class I Federal area is 
located establishes a reasonable progress goal for the most impaired 
days that provides for a slower rate of improvement in visibility than 
the uniform rate of progress calculated under paragraph (f)(1)(vi) of 
this section, the State must demonstrate, based on the analysis required 
by paragraph (f)(2)(i) of this section, that there are no additional 
emission reduction measures for anthropogenic sources or groups of 
sources in the State that may reasonably be anticipated to contribute to 
visibility impairment in the Class I area that would be reasonable to 
include in the long-term strategy. The State must provide a robust 
demonstration, including documenting the criteria used to determine 
which sources or groups or sources were evaluated and how the four 
factors required by paragraph (f)(2)(i) were taken into consideration in 
selecting the measures for inclusion in its long-term strategy. The 
State must provide to the public for review as part of its 
implementation plan an assessment of the number of years it would take 
to attain natural visibility conditions if visibility improvement were 
to continue at the rate of progress selected by the State as reasonable 
for the implementation period.
    (B) If a State contains sources which are reasonably anticipated to 
contribute to visibility impairment in a mandatory Class I Federal area 
in another State for which a demonstration by the other State is 
required under (f)(3)(ii)(A), the State must demonstrate that there are 
no additional emission reduction measures for anthropogenic sources or 
groups of sources in the State that may reasonably be anticipated to 
contribute to visibility impairment in the Class I area that would be 
reasonable to include in its own long-term strategy. The State must 
provide a robust demonstration, including documenting the criteria used 
to determine which sources or groups or sources were evaluated and how 
the four factors required by paragraph (f)(2)(i) were taken into 
consideration in selecting the measures for inclusion in its long-term 
strategy.
    (iii) The reasonable progress goals established by the State are not 
directly enforceable but will be considered by the Administrator in 
evaluating the adequacy of the measures in the implementation plan in 
providing for reasonable progress towards achieving natural visibility 
conditions at that area.
    (iv) In determining whether the State's goal for visibility 
improvement provides for reasonable progress towards natural visibility 
conditions, the Administrator will also evaluate the demonstrations 
developed by the State pursuant to paragraphs (f)(2) and (f)(3)(ii)(A) 
of this section and the demonstrations provided by other States pursuant 
to paragraphs (f)(2) and (f)(3)(ii)(B) of this section.
    (4) If the Administrator, Regional Administrator, or the affected 
Federal Land Manager has advised a State of a need for additional 
monitoring to assess reasonably attributable visibility impairment at 
the mandatory Class I Federal area in addition to the monitoring 
currently being conducted, the State must include in the plan revision 
an appropriate strategy for evaluating reasonably attributable 
visibility impairment in the mandatory Class I Federal area by visual 
observation or other appropriate monitoring techniques.
    (5) So that the plan revision will serve also as a progress report, 
the State must address in the plan revision the requirements of 
paragraphs (g)(1) through (5) of this section. However, the period to be 
addressed for these elements shall be the period since the most recent 
progress report.
    (6) Monitoring strategy and other implementation plan requirements. 
The State must submit with the implementation plan a monitoring strategy 
for measuring, characterizing, and reporting of regional haze visibility 
impairment that is representative of all mandatory Class I Federal areas 
within the State. Compliance with this requirement may be met through 
participation in the Interagency Monitoring of Protected Visual 
Environments network. The implementation plan must also provide for the 
following:
    (i) The establishment of any additional monitoring sites or 
equipment

[[Page 318]]

needed to assess whether reasonable progress goals to address regional 
haze for all mandatory Class I Federal areas within the State are being 
achieved.
    (ii) Procedures by which monitoring data and other information are 
used in determining the contribution of emissions from within the State 
to regional haze visibility impairment at mandatory Class I Federal 
areas both within and outside the State.
    (iii) For a State with no mandatory Class I Federal areas, 
procedures by which monitoring data and other information are used in 
determining the contribution of emissions from within the State to 
regional haze visibility impairment at mandatory Class I Federal areas 
in other States.
    (iv) The implementation plan must provide for the reporting of all 
visibility monitoring data to the Administrator at least annually for 
each mandatory Class I Federal area in the State. To the extent 
possible, the State should report visibility monitoring data 
electronically.
    (v) A statewide inventory of emissions of pollutants that are 
reasonably anticipated to cause or contribute to visibility impairment 
in any mandatory Class I Federal area. The inventory must include 
emissions for the most recent year for which data are available, and 
estimates of future projected emissions. The State must also include a 
commitment to update the inventory periodically.
    (vi) Other elements, including reporting, recordkeeping, and other 
measures, necessary to assess and report on visibility.
    (g) Requirements for periodic reports describing progress towards 
the reasonable progress goals. Each State identified in Sec. 51.300(b) 
must periodically submit a report to the Administrator evaluating 
progress towards the reasonable progress goal for each mandatory Class I 
Federal area located within the State and in each mandatory Class I 
Federal area located outside the State that may be affected by emissions 
from within the State. The first progress report is due 5 years from 
submittal of the initial implementation plan addressing paragraphs (d) 
and (e) of this section. The first progress reports must be in the form 
of implementation plan revisions that comply with the procedural 
requirements of Sec. 51.102 and Sec. 51.103. Subsequent progress 
reports are due by January 31, 2025, July 31, 2033, and every 10 years 
thereafter. Subsequent progress reports must be made available for 
public inspection and comment for at least 30 days prior to submission 
to EPA and all comments received from the public must be submitted to 
EPA along with the subsequent progress report, along with an explanation 
of any changes to the progress report made in response to these 
comments. Periodic progress reports must contain at a minimum the 
following elements:
    (1) A description of the status of implementation of all measures 
included in the implementation plan for achieving reasonable progress 
goals for mandatory Class I Federal areas both within and outside the 
State.
    (2) A summary of the emissions reductions achieved throughout the 
State through implementation of the measures described in paragraph 
(g)(1) of this section.
    (3) For each mandatory Class I Federal area within the State, the 
State must assess the following visibility conditions and changes, with 
values for most impaired, least impaired and/or clearest days as 
applicable expressed in terms of 5-year averages of these annual values. 
The period for calculating current visibility conditions is the most 
recent 5-year period preceding the required date of the progress report 
for which data are available as of a date 6 months preceding the 
required date of the progress report.
    (i)(A) Progress reports due before January 31, 2025. The current 
visibility conditions for the most impaired and least impaired days.
    (B) Progress reports due on and after January 31, 2025. The current 
visibility conditions for the most impaired and clearest days;
    (ii)(A) Progress reports due before January 31, 2025. The difference 
between current visibility conditions for the most impaired and least 
impaired days and baseline visibility conditions.
    (B) Progress reports due on and after January 31, 2025. The 
difference between current visibility conditions for

[[Page 319]]

the most impaired and clearest days and baseline visibility conditions.
    (iii)(A) Progress reports due before January 31, 2025. The change in 
visibility impairment for the most impaired and least impaired days over 
the period since the period addressed in the most recent plan required 
under paragraph (f) of this section.
    (B) Progress reports due on and after January 31, 2025. The change 
in visibility impairment for the most impaired and clearest days over 
the period since the period addressed in the most recent plan required 
under paragraph (f) of this section.
    (4) An analysis tracking the change over the period since the period 
addressed in the most recent plan required under paragraph (f) of this 
section in emissions of pollutants contributing to visibility impairment 
from all sources and activities within the State. Emissions changes 
should be identified by type of source or activity. With respect to all 
sources and activities, the analysis must extend at least through the 
most recent year for which the state has submitted emission inventory 
information to the Administrator in compliance with the triennial 
reporting requirements of subpart A of this part as of a date 6 months 
preceding the required date of the progress report. With respect to 
sources that report directly to a centralized emissions data system 
operated by the Administrator, the analysis must extend through the most 
recent year for which the Administrator has provided a State-level 
summary of such reported data or an internet-based tool by which the 
State may obtain such a summary as of a date 6 months preceding the 
required date of the progress report. The State is not required to 
backcast previously reported emissions to be consistent with more recent 
emissions estimation procedures, and may draw attention to actual or 
possible inconsistencies created by changes in estimation procedures.
    (5) An assessment of any significant changes in anthropogenic 
emissions within or outside the State that have occurred since the 
period addressed in the most recent plan required under paragraph (f) of 
this section including whether or not these changes in anthropogenic 
emissions were anticipated in that most recent plan and whether they 
have limited or impeded progress in reducing pollutant emissions and 
improving visibility.
    (6) An assessment of whether the current implementation plan 
elements and strategies are sufficient to enable the State, or other 
States with mandatory Class I Federal areas affected by emissions from 
the State, to meet all established reasonable progress goals for the 
period covered by the most recent plan required under paragraph (f) of 
this section.
    (7) For progress reports for the first implementation period only, a 
review of the State's visibility monitoring strategy and any 
modifications to the strategy as necessary.
    (8) For a state with a long-term strategy that includes a smoke 
management program for prescribed fires on wildland that conducts a 
periodic program assessment, a summary of the most recent periodic 
assessment of the smoke management program including conclusions if any 
that were reached in the assessment as to whether the program is meeting 
its goals regarding improving ecosystem health and reducing the damaging 
effects of catastrophic wildfires.
    (h) Determination of the adequacy of existing implementation plan. 
At the same time the State is required to submit any progress report to 
EPA in accordance with paragraph (g) of this section, the State must 
also take one of the following actions based upon the information 
presented in the progress report:
    (1) If the State determines that the existing implementation plan 
requires no further substantive revision at this time in order to 
achieve established goals for visibility improvement and emissions 
reductions, the State must provide to the Administrator a declaration 
that revision of the existing implementation plan is not needed at this 
time.
    (2) If the State determines that the implementation plan is or may 
be inadequate to ensure reasonable progress due to emissions from 
sources in another State(s) which participated in a regional planning 
process, the State

[[Page 320]]

must provide notification to the Administrator and to the other State(s) 
which participated in the regional planning process with the States. The 
State must also collaborate with the other State(s) through the regional 
planning process for the purpose of developing additional strategies to 
address the plan's deficiencies.
    (3) Where the State determines that the implementation plan is or 
may be inadequate to ensure reasonable progress due to emissions from 
sources in another country, the State shall provide notification, along 
with available information, to the Administrator.
    (4) Where the State determines that the implementation plan is or 
may be inadequate to ensure reasonable progress due to emissions from 
sources within the State, the State shall revise its implementation plan 
to address the plan's deficiencies within one year.
    (i) What are the requirements for State and Federal Land Manager 
coordination? (1) By November 29, 1999, the State must identify in 
writing to the Federal Land Managers the title of the official to which 
the Federal Land Manager of any mandatory Class I Federal area can 
submit any recommendations on the implementation of this subpart 
including, but not limited to:
    (i) Identification of impairment of visibility in any mandatory 
Class I Federal area(s); and
    (ii) Identification of elements for inclusion in the visibility 
monitoring strategy required by Sec. 51.305 and this section.
    (2) The State must provide the Federal Land Manager with an 
opportunity for consultation, in person at a point early enough in the 
State's policy analyses of its long-term strategy emission reduction 
obligation so that information and recommendations provided by the 
Federal Land Manager can meaningfully inform the State's decisions on 
the long-term strategy. The opportunity for consultation will be deemed 
to have been early enough if the consultation has taken place at least 
120 days prior to holding any public hearing or other public comment 
opportunity on an implementation plan (or plan revision) for regional 
haze required by this subpart. The opportunity for consultation on an 
implementation plan (or plan revision) or on a progress report must be 
provided no less than 60 days prior to said public hearing or public 
comment opportunity. This consultation must include the opportunity for 
the affected Federal Land Managers to discuss their:
    (i) Assessment of impairment of visibility in any mandatory Class I 
Federal area; and
    (ii) Recommendations on the development and implementation of 
strategies to address visibility impairment.
    (3) In developing any implementation plan (or plan revision) or 
progress report, the State must include a description of how it 
addressed any comments provided by the Federal Land Managers.
    (4) The plan (or plan revision) must provide procedures for 
continuing consultation between the State and Federal Land Manager on 
the implementation of the visibility protection program required by this 
subpart, including development and review of implementation plan 
revisions and progress reports, and on the implementation of other 
programs having the potential to contribute to impairment of visibility 
in mandatory Class I Federal areas.

[64 FR 35765, July 1, 1999, as amended at 70 FR 39156, July 6, 2005; 71 
FR 60631, Oct. 13, 2006; 77 FR 33656, June 7, 2012; 82 FR 3124, Jan. 10, 
2017]



Sec. 51.309  Requirements related to the Grand Canyon Visibility 
Transport Commission.

    (a) What is the purpose of this section? This section establishes 
the requirements for the first regional haze implementation plan to 
address regional haze visibility impairment in the 16 Class I areas 
covered by the Grand Canyon Visibility Transport Commission Report. For 
the period through 2018, certain States (defined in paragraph (b) of 
this section as Transport Region States) may choose to implement the 
Commission's recommendations within the framework of the national 
regional haze program and applicable requirements of the Act by 
complying with the provisions of this section. If a Transport Region 
State submits an implementation plan which is approved by EPA as meeting

[[Page 321]]

the requirements of this section, it will be deemed to comply with the 
requirements for reasonable progress with respect to the 16 Class I 
areas for the period from approval of the plan through 2018. Any 
Transport Region State electing not to submit an implementation plan 
under this section is subject to the requirements of Sec. 51.308 in the 
same manner and to the same extent as any State not included within the 
Transport Region. Except as provided in paragraph (g) of this section, 
each Transport Region State is also subject to the requirements of Sec. 
51.308 with respect to any other Federal mandatory Class I areas within 
the State or affected by emissions from the State.
    (b) Definitions. For the purposes of this section:
    (1) 16 Class I areas means the following mandatory Class I Federal 
areas on the Colorado Plateau: Grand Canyon National Park, Sycamore 
Canyon Wilderness, Petrified Forest National Park, Mount Baldy 
Wilderness, San Pedro Parks Wilderness, Mesa Verde National Park, 
Weminuche Wilderness, Black Canyon of the Gunnison Wilderness, West Elk 
Wilderness, Maroon Bells Wilderness, Flat Tops Wilderness, Arches 
National Park, Canyonlands National Park, Capital Reef National Park, 
Bryce Canyon National Park, and Zion National Park.
    (2) Transport Region State means one of the States that is included 
within the Transport Region addressed by the Grand Canyon Visibility 
Transport Commission (Arizona, California, Colorado, Idaho, Nevada, New 
Mexico, Oregon, Utah, and Wyoming).
    (3) Commission Report means the report of the Grand Canyon 
Visibility Transport Commission entitled ``Recommendations for Improving 
Western Vistas,'' dated June 10, 1996.
    (4) Fire means wildfire, wildland fire, prescribed fire, and 
agricultural burning conducted and occurring on Federal, State, and 
private wildlands and farmlands.
    (5) Milestone means the maximum level of annual regional 
SO2 emissions, in tons per year, for a given year, assessed 
annually, through the year 2018, consistent with paragraph (d)(4) of 
this section.
    (6) Continuous decline in total mobile source emissions means that 
the projected level of emissions from mobile sources of each listed 
pollutant in 2008, 2013, and 2018, are less than the projected level of 
emissions from mobile sources of each listed pollutant for the previous 
period (i.e., 2008 less than 2003; 2013 less than 2008; and 2018 less 
than 2013).
    (7) Base year means the year for which data for a source included 
within the program were used by the WRAP to calculate emissions as a 
starting point for development of the milestone required by paragraph 
(d)(4)(i) of this section.
    (8)-(12) [Reserved]
    (13) Eligible renewable energy resource, for purposes of 40 CFR 
51.309, means electricity generated by non-nuclear and non-fossil low or 
no air emission technologies.
    (c) Implementation Plan Schedule. Each Transport Region State 
electing to submit an implementation plan under this section must submit 
such a plan no later than December 17, 2007. Indian Tribes may submit 
implementation plans after this deadline.
    (d) Requirements of the first implementation plan for States 
electing to adopt all of the recommendations of the Commission Report. 
Except as provided for in paragraph (e) of this section, each Transport 
Region State must submit an implementation plan that meets the following 
requirements:
    (1) Time period covered.  The implementation plan must be effective 
through December 31, 2018 and continue in effect until an implementation 
plan revision is approved by EPA in accordance with Sec. 51.308(f).
    (2) Projection of visibility improvement. For each of the 16 
mandatory Class I areas located within the Transport Region State, the 
plan must include a projection of the improvement in visibility 
conditions (expressed in deciviews, and in any additional ambient 
visibility metrics deemed appropriate by the State) expected through the 
year 2018 for the most impaired and least impaired days, based on the 
implementation of all measures as required in the Commission report and 
the provisions in this section. The projection must be made in 
consultation

[[Page 322]]

with other Transport Region States with sources which may be reasonably 
anticipated to contribute to visibility impairment in the relevant Class 
I area. The projection may be based on a satisfactory regional analysis.
    (3) Treatment of clean-air corridors. The plan must describe and 
provide for implementation of comprehensive emission tracking strategies 
for clean-air corridors to ensure that the visibility does not degrade 
on the least-impaired days at any of the 16 Class I areas. The strategy 
must include:
    (i) An identification of clean-air corridors. The EPA will evaluate 
the State's identification of such corridors based upon the reports of 
the Commission's Meteorology Subcommittee and any future updates by a 
successor organization;
    (ii) Within areas that are clean-air corridors, an identification of 
patterns of growth or specific sites of growth that could cause, or are 
causing, significant emissions increases that could have, or are having, 
visibility impairment at one or more of the 16 Class I areas.
    (iii) In areas outside of clean-air corridors, an identification of 
significant emissions growth that could begin, or is beginning, to 
impair the quality of air in the corridor and thereby lead to visibility 
degradation for the least-impaired days in one or more of the 16 Class I 
areas.
    (iv) If impairment of air quality in clean air corridors is 
identified pursuant to paragraphs (d)(3)(ii) and (iii) of this section, 
an analysis of the effects of increased emissions, including provisions 
for the identification of the need for additional emission reductions 
measures, and implementation of the additional measures where necessary.
    (v) A determination of whether other clean air corridors exist for 
any of the 16 Class I areas. For any such clean air corridors, an 
identification of the necessary measures to protect against future 
degradation of air quality in any of the 16 Class I areas.
    (4) Implementation of stationary source reductions. The first 
implementation plan submission must include:
    (i) Provisions for stationary source emissions of SO2. 
The plan submission must include a SO2 program that contains 
quantitative emissions milestones for stationary source SO2 
emissions for each year through 2018. After the first two years of the 
program, compliance with the annual milestones may be measured by 
comparing a three-year rolling average of actual emissions with a 
rolling average of the emissions milestones for the same three years. 
During the first two years of the program, compliance with the 
milestones may be measured by a methodology of the States' choosing, so 
long as all States in the program use the same methodology. Compliance 
with the 2018 milestone shall be measured by comparing actual emissions 
from the year 2018 with the 2018 milestone. The milestones must provide 
for steady and continuing emissions reductions through 2018 consistent 
with the Commission's definition of reasonable progress, its goal of 50 
to 70 percent reduction in SO2 emissions from 1990 actual 
emission levels by 2040, applicable requirements under the CAA, and the 
timing of implementation plan assessments of progress and identification 
of any deficiencies which will be due in the years 2013 and 2018. The 
milestones must be shown to provide for greater reasonable progress than 
would be achieved by application of BART pursuant to Sec. 51.308(e)(2).
    (ii) Documentation of emissions calculation methods for 
SO2. The plan submission must include documentation of the 
specific methodology used to calculate SO2 emissions during 
the base year for each emitting unit included in the program. The 
implementation plan must also provide for documentation of any change to 
the specific methodology used to calculate emissions at any emitting 
unit for any year after the base year.
    (iii) Monitoring, recordkeeping, and reporting of SO2 
emissions. The plan submission must include provisions requiring the 
monitoring, recordkeeping, and annual reporting of actual stationary 
source SO2 emissions within the State. The monitoring, 
recordkeeping, and reporting data must be sufficient to determine 
annually whether the milestone for each year through 2018 is achieved. 
The plan submission must provide for reporting of

[[Page 323]]

these data by the State to the Administrator and to the regional 
planning organization. The plan must provide for retention of records 
for at least 10 years from the establishment of the record.
    (iv) Criteria and Procedures for a Market Trading Program. The plan 
must include the criteria and procedures for conducting an annual 
evaluation of whether the milestone is achieved and, in accordance with 
paragraph (d)(4)(v) of this section, for activating a market trading 
program in the event the milestone is not achieved. A draft of the 
annual report evaluating whether the milestone for each year is achieved 
shall be completed no later than 12 months from the end of each 
milestone year. The plan must also provide for assessments of the 
program in the years 2013 and 2018.
    (v) Market trading program. The implementation plan must include 
requirements for a market trading program to be implemented in the event 
that a milestone is not achieved. The plan shall require that the market 
trading program be activated beginning no later than 15 months after the 
end of the first year in which the milestone is not achieved. The plan 
shall also require that sources comply, as soon as practicable, with the 
requirement to hold allowances covering their emissions. Such market 
trading program must be sufficient to achieve the milestones in 
paragraph (d)(4)(i) of this section, and must be consistent with the 
elements for such programs outlined in Sec. 51.308(e)(2)(vi). Such a 
program may include a geographic enhancement to the program to address 
the requirement under Sec. 51.302(b) related to reasonably attributable 
impairment from the pollutants covered under the program.
    (vi) Provision for the 2018 milestone.
    (A) Unless and until a revised implementation plan is submitted in 
accordance with Sec. 51.308(f) and approved by EPA, the implementation 
plan shall prohibit emissions from covered stationary sources in any 
year beginning in 2018 that exceed the year 2018 milestone. In no event 
shall a market-based program approved under Sec. 51.308(f) allow an 
emissions cap for SO2 that is less stringent than the 2018 
milestone, unless the milestones are replaced by a different program 
approved by EPA as meeting the BART and reasonable progress requirements 
established in Sec. 51.308.
    (B) The implementation plan must provide a framework, including 
financial penalties for excess emissions based on the 2018 milestone, 
sufficient to ensure that the 2018 milestone will be met even if the 
implementation of the market trading program in paragraph (d)(4)(v) of 
this section has not yet been triggered, or the source allowance 
compliance provision of the trading program is not yet in effect.
    (vii) Provisions for stationary source emissions of NOX 
and PM. The implementation plan must contain any necessary long term 
strategies and BART requirements for stationary source PM and 
NOX emissions. Any such BART provisions may be submitted 
pursuant to either Sec. 51.308(e)(1) or '51.308(e)(2).
    (5) Mobile sources. The plan submission must provide for:
    (i) Statewide inventories of onroad and nonroad mobile source 
emissions of VOC, NOX, SO2, PM2.5, 
elemental carbon, and organic carbon for the years 2003, 2008, 2013, and 
2018.
    (A) The inventories must demonstrate a continuous decline in total 
mobile source emissions (onroad plus nonroad; tailpipe and evaporative) 
of VOC, NOX, PM2.5, elemental carbon, and organic 
carbon, evaluated separately. If the inventories show a continuous 
decline in total mobile source emissions of each of these pollutants 
over the period 2003-2018, no further action is required as part of this 
plan to address mobile source emissions of these pollutants. If the 
inventories do not show a continuous decline in mobile source emissions 
of one or more of these pollutants over the period 2003-2018, the plan 
submission must provide for an implementation plan revision by no later 
than December 31, 2008 containing any necessary long-term strategies to 
achieve a continuous decline in total mobile source emissions of the 
pollutant(s), to the extent practicable, considering economic and 
technological reasonableness and federal preemption of vehicle standards 
and fuel standards under title II of the CAA.

[[Page 324]]

    (B) The plan submission must also provide for an implementation plan 
revision by no later than December 31, 2008 containing any long-term 
strategies necessary to reduce emissions of SO2 from nonroad 
mobile sources, consistent with the goal of reasonable progress. In 
assessing the need for such long-term strategies, the State may consider 
emissions reductions achieved or anticipated from any new Federal 
standards for sulfur in nonroad diesel fuel.
    (ii) Interim reports to EPA and the public in years 2003, 2008, 
2013, and 2018 on the implementation status of the regional and local 
strategies recommended by the Commission Report to address mobile source 
emissions.
    (6) Programs related to fire. The plan must provide for:
    (i) Documentation that all Federal, State, and private prescribed 
fire programs within the State evaluate and address the degree 
visibility impairment from smoke in their planning and application. In 
addition the plan must include smoke management programs that include 
all necessary components including, but not limited to, actions to 
minimize emissions, evaluation of smoke dispersion, alternatives to 
fire, public notification, air quality monitoring, surveillance and 
enforcement, and program evaluation.
    (ii) A statewide inventory and emissions tracking system (spatial 
and temporal) of VOC, NOX, elemental and organic carbon, and 
fine particle emissions from fire. In reporting and tracking emissions 
from fire from within the State, States may use information from 
regional data-gathering and tracking initiatives.
    (iii) Identification and removal wherever feasible of any 
administrative barriers to the use of alternatives to burning in 
Federal, State, and private prescribed fire programs within the State.
    (iv) Enhanced smoke management programs for fire that consider 
visibility effects, not only health and nuisance objectives, and that 
are based on the criteria of efficiency, economics, law, emission 
reduction opportunities, land management objectives, and reduction of 
visibility impact.
    (v) Establishment of annual emission goals for fire, excluding 
wildfire, that will minimize emission increases from fire to the maximum 
extent feasible and that are established in cooperation with States, 
tribes, Federal land management agencies, and private entities.
    (7) Area sources of dust emissions from paved and unpaved roads. The 
plan must include an assessment of the impact of dust emissions from 
paved and unpaved roads on visibility conditions in the 16 Class I 
Areas. If such dust emissions are determined to be a significant 
contributor to visibility impairment in the 16 Class I areas, the State 
must implement emissions management strategies to address the impact as 
necessary and appropriate.
    (8) Pollution prevention. The plan must provide for:
    (i) An initial summary of all pollution prevention programs 
currently in place, an inventory of all renewable energy generation 
capacity and production in use, or planned as of the year 2002 
(expressed in megawatts and megawatt-hours), the total energy generation 
capacity and production for the State, the percent of the total that is 
renewable energy, and the State's anticipated contribution toward the 
renewable energy goals for 2005 and 2015, as provided in paragraph 
(d)(8)(vi) of this section.
    (ii) Programs to provide incentives that reward efforts that go 
beyond compliance and/or achieve early compliance with air-pollution 
related requirements.
    (iii) Programs to preserve and expand energy conservation efforts.
    (iv) The identification of specific areas where renewable energy has 
the potential to supply power where it is now lacking and where 
renewable energy is most cost-effective.
    (v) Projections of the short- and long-term emissions reductions, 
visibility improvements, cost savings, and secondary benefits associated 
with the renewable energy goals, energy efficiency and pollution 
prevention activities.
    (vi) A description of the programs relied on to achieve the State's 
contribution toward the Commission's goal that renewable energy will 
comprise 10 percent of the regional power needs by 2005 and 20 percent 
by 2015, and a demonstration of the progress toward achievement of the 
renewable energy

[[Page 325]]

goals in the years 2003, 2008, 2013, and 2018. This description must 
include documentation of the potential for renewable energy resources, 
the percentage of renewable energy associated with new power generation 
projects implemented or planned, and the renewable energy generation 
capacity and production in use and planned in the State. To the extent 
that it is not feasible for a State to meet its contribution to the 
regional renewable energy goals, the State must identify in the progress 
reports the measures implemented to achieve its contribution and explain 
why meeting the State's contribution was not feasible.
    (9) Implementation of additional recommendations. The plan must 
provide for implementation of all other recommendations in the 
Commission report that can be practicably included as enforceable 
emission limits, schedules of compliance, or other enforceable measures 
(including economic incentives) to make reasonable progress toward 
remedying existing and preventing future regional haze in the 16 Class I 
areas. The State must provide a report to EPA and the public in 2003, 
2008, 2013, and 2018 on the progress toward developing and implementing 
policy or strategy options recommended in the Commission Report.
    (10) Periodic implementation plan revisions and progress reports. 
Each Transport Region State must submit to the Administrator periodic 
reports in the years 2013 and as specified for subsequent progress 
reports in Sec. 51.308(g). The progress report due in 2013 must be in 
the form of an implementation plan revision that complies with the 
procedural requirements of Sec. Sec. 51.102 and 51.103.
    (i) The report due in 2013 will assess the area for reasonable 
progress as provided in this section for mandatory Class I Federal 
area(s) located within the State and for mandatory Class I Federal 
area(s) located outside the State that may be affected by emissions from 
within the State. This demonstration may be based on assessments 
conducted by the States and/or a regional planning body. The progress 
report due in 2013 must contain at a minimum the following elements:
    (A) A description of the status of implementation of all measures 
included in the implementation plan for achieving reasonable progress 
goals for mandatory Class I Federal areas both within and outside the 
State.
    (B) A summary of the emissions reductions achieved throughout the 
State through implementation of the measures described in paragraph 
(d)(10)(i)(A) of this section.
    (C) For each mandatory Class I Federal area within the State, an 
assessment of the following: the current visibility conditions for the 
most impaired and least impaired days; the difference between current 
visibility conditions for the most impaired and least impaired days and 
baseline visibility conditions; the change in visibility impairment for 
the most impaired and least impaired days over the past 5 years.
    (D) An analysis tracking the change over the past 5 years in 
emissions of pollutants contributing to visibility impairment from all 
sources and activities within the State. Emissions changes should be 
identified by type of source or activity. The analysis must be based on 
the most recent updated emissions inventory, with estimates projected 
forward as necessary and appropriate, to account for emissions changes 
during the applicable 5-year period.
    (E) An assessment of any significant changes in anthropogenic 
emissions within or outside the State that have occurred over the past 5 
years that have limited or impeded progress in reducing pollutant 
emissions and improving visibility.
    (F) An assessment of whether the current implementation plan 
elements and strategies are sufficient to enable the State, or other 
States with mandatory Federal Class I areas affected by emissions from 
the State, to meet all established reasonable progress goals.
    (G) A review of the State's visibility monitoring strategy and any 
modifications to the strategy as necessary.
    (ii) At the same time the State is required to submit the 5-year 
progress report due in 2013 to EPA in accordance with paragraph 
(d)(10)(i) of this section, the State must also take one of the 
following actions based upon the information presented in the progress 
report:

[[Page 326]]

    (A) If the State determines that the existing implementation plan 
requires no further substantive revision at this time in order to 
achieve established goals for visibility improvement and emissions 
reductions, the State must provide to the Administrator a negative 
declaration that further revision of the existing implementation plan is 
not needed at this time.
    (B) If the State determines that the implementation plan is or may 
be inadequate to ensure reasonable progress due to emissions from 
sources in another State(s) which participated in a regional planning 
process, the State must provide notification to the Administrator and to 
the other State(s) which participated in the regional planning process 
with the States. The State must also collaborate with the other State(s) 
through the regional planning process for the purpose of developing 
additional strategies to address the plan's deficiencies.
    (C) Where the State determines that the implementation plan is or 
may be inadequate to ensure reasonable progress due to emissions from 
sources in another country, the State shall provide notification, along 
with available information, to the Administrator.
    (D) Where the State determines that the implementation plan is or 
may be inadequate to ensure reasonable progress due to emissions from 
within the State, the State shall develop additional strategies to 
address the plan deficiencies and revise the implementation plan no 
later than one year from the date that the progress report was due.
    (iii) The requirements of Sec. 51.308(g) regarding requirements for 
periodic reports describing progress towards the reasonable progress 
goals apply to States submitting plans under this section, with respect 
to subsequent progress reports due after 2013.
    (iv) The requirements of Sec. 51.308(h) regarding determinations of 
the adequacy of existing implementation plans apply to States submitting 
plans under this section, with respect to subsequent progress reports 
due after 2013.
    (11) State planning and interstate coordination. In complying with 
the requirements of this section, States may include emission reductions 
strategies that are based on coordinated implementation with other 
States. Examples of these strategies include economic incentive programs 
and transboundary emissions trading programs. The implementation plan 
must include documentation of the technical and policy basis for the 
individual State apportionment (or the procedures for apportionment 
throughout the trans-boundary region), the contribution addressed by the 
State's plan, how it coordinates with other State plans, and compliance 
with any other appropriate implementation plan approvability criteria. 
States may rely on the relevant technical, policy and other analyses 
developed by a regional entity (such as the Western Regional Air 
Partnership) in providing such documentation. Conversely, States may 
elect to develop their own programs without relying on work products 
from a regional entity.
    (12) Tribal implementation. Consistent with 40 CFR Part 49, tribes 
within the Transport Region may implement the required visibility 
programs for the 16 Class I areas, in the same manner as States, 
regardless of whether such tribes have participated as members of a 
visibility transport commission.
    (e) States electing not to implement the commission recommendations. 
Any Transport Region State may elect not to implement the Commission 
recommendations set forth in paragraph (d) of this section. Such States 
are required to comply with the timelines and requirements of Sec. 
51.308. Any Transport Region State electing not to implement the 
Commission recommendations must advise the other States in the Transport 
Region of the nature of the program and the effect of the program on 
visibility-impairing emissions, so that other States can take this 
information into account in developing programs under this section.
    (f) [Reserved]
    (g) Additional Class I areas. Each Transport Region State 
implementing the provisions of this section as the basis for 
demonstrating reasonable progress for mandatory Class I Federal areas 
other than the 16 Class I areas must include the following provisions

[[Page 327]]

in its implementation plan. If a Transport Region State submits an 
implementation plan which is approved by EPA as meeting the requirements 
of this section, it will be deemed to comply with the requirements for 
reasonable progress for the period from approval of the plan to 2018.
    (1) A demonstration of expected visibility conditions for the most 
impaired and least impaired days at the additional mandatory Class I 
Federal area(s) based on emissions projections from the long-term 
strategies in the implementation plan. This demonstration may be based 
on assessments conducted by the States and/or a regional planning body.
    (2) Provisions establishing reasonable progress goals and 
implementing any additional measures necessary to demonstrate reasonable 
progress for the additional mandatory Federal Class I areas. These 
provisions must comply with the provisions of Sec. 51.308(d)(1) through 
(4).
    (i) In developing long-term strategies pursuant to Sec. 
51.308(d)(3), the State may build upon the strategies implemented under 
paragraph (d) of this section, and take full credit for the visibility 
improvement achieved through these strategies.
    (ii) The requirement under Sec. 51.308(e) related to Best Available 
Retrofit Technology for regional haze is deemed to be satisfied for 
pollutants addressed by the milestones and backstop trading program if, 
in establishing the emission reductions milestones under paragraph 
(d)(4) of this section, it is shown that greater reasonable progress 
will be achieved for these additional Class I areas than would be 
achieved through the application of source-specific BART emission 
limitations under Sec. 51.308(e)(1).
    (iii) The Transport Region State may consider whether any strategies 
necessary to achieve the reasonable progress goals required by paragraph 
(g)(2) of this section are incompatible with the strategies implemented 
under paragraph (d) of this section to the extent the State adequately 
demonstrates that the incompatibility is related to the costs of the 
compliance, the time necessary for compliance, the energy and nonair 
quality environmental impacts of compliance, or the remaining useful 
life of any existing source subject to such requirements.

[64 FR 35769, July 1, 1999, as amended at 68 FR 33784, June 5, 2003; 68 
FR 39846, July 3, 2003; 68 FR 61369, Oct. 28, 2003; 68 FR 71014, Dec. 
22, 2003; 71 FR 60632, Oct. 13, 2006; 82 FR 3128, Jan. 10, 2017]



                            Subpart Q_Reports

    Authority: Secs. 110, 301(a), 313, 319, Clean Air Act (42 U.S.C. 
7410, 7601(a), 7613, 7619).

    Source: 44 FR 27569, May 10, 1979, unless otherwise noted.

                       Air Quality Data Reporting



Sec. 51.320  Annual air quality data report.

    The requirements for reporting air quality data collected for 
purposes of the plan are located in subpart C of part 58 of this 
chapter.

               Source Emissions and State Action Reporting



Sec. 51.321  Annual source emissions and State action report.

    The State agency shall report to the Administrator (through the 
appropriate Regional Office) information as specified in Sec. Sec. 
51.322 through 51.326.

[67 FR 39615, June 10, 2002]



Sec. 51.322  Sources subject to emissions reporting.

    The requirements for reporting emissions data under the plan are in 
subpart A of this part 51.

[67 FR 39615, June 10, 2002]



Sec. 51.323  Reportable emissions data and information.

    The requirements for reportable emissions data and information under 
the plan are in subpart A of this part 51.

[67 FR 39615, June 10, 2002]



Sec. 51.324  Progress in plan enforcement.

    (a) For each point source, the State shall report any achievement 
made during the reporting period of any increment of progress of 
compliance schedules required by:
    (1) The applicable plan, or

[[Page 328]]

    (2) Any enforcement order or other State action required to be 
submitted pursuant to Sec. 51.327.
    (b) For each point source, the State shall report any enforcement 
action taken during the reporting period and not submitted under Sec. 
51.327 which results in civil or criminal penalties.



Sec. 51.326  Reportable revisions.

    The State shall identify and describe all substantive plan revisions 
during the reporting period of the applicable plan other than revisions 
to rules and regulations or compliance schedules submitted in accordance 
with Sec. 51.6(d). Substantive revisions shall include but are not 
limited to changes in stack-test procedures for determining compliance 
with applicable regulations, modifications in the projected total 
manpower needs to carry out the approved plan, and all changes in 
responsibilities given to local agencies to carry out various portions 
of the plan.



Sec. 51.327  Enforcement orders and other State actions.

    (a) Any State enforcement order, including any State court order, 
must be submitted to the Administrator within 60 days of its issuance or 
adoption by the State.
    (b) A State enforcement order or other State action must be 
submitted as a revision to the applicable implementation plan pursuant 
to Sec. 51.104 and approved by the Administrator in order to be 
considered a revision to such plan.

[36 FR 22398, Nov. 25, 1971, as amended at 51 FR 40675, Nov. 7, 1986]



Sec. 51.328  [Reserved]



                          Subpart R_Extensions



Sec. 51.341  Request for 18-month extension.

    (a) Upon request of the State made in accordance with this section, 
the Administrator may, whenever he determines necessary, extend, for a 
period not to exceed 18 months, the deadline for submitting that portion 
of a plan that implements a secondary standard.
    (b) Any such request must show that attainment of the secondary 
standards will require emission reductions exceeding those which can be 
achieved through the application of reasonably available control 
technology.
    (c) Any such request for extension of the deadline with respect to 
any State's portion of an interstate region must be submitted jointly 
with requests for such extensions from all other States within the 
region or must show that all such States have been notified of such 
request.
    (d) Any such request must be submitted sufficiently early to permit 
development of a plan prior to the deadline in the event that such 
request is denied.

[51 FR 40675, Nov. 7, 1986]



          Subpart S_Inspection/Maintenance Program Requirements

    Source: 57 FR 52987, Nov. 5, 1992, unless otherwise noted.



Sec. 51.350  Applicability.

    Inspection/maintenance (I/M) programs are required in both ozone and 
carbon monoxide (CO) nonattainment areas, depending upon population and 
nonattainment classification or design value.
    (a) Nonattainment area classification and population criteria. (1) 
States or areas within an ozone transport region shall implement 
enhanced I/M programs in any metropolitan statistical area (MSA), or 
portion of an MSA, within the State or area with a 1990 population of 
100,000 or more as defined by the Office of Management and Budget (OMB) 
regardless of the area's attainment classification. In the case of a 
multi-state MSA, enhanced I/M shall be implemented in all ozone 
transport region portions if the sum of these portions has a population 
of 100,000 or more, irrespective of the population of the portion in the 
individual ozone transport region State or area.
    (2) Apart from those areas described in paragraph (a)(1) of this 
section, any area classified as serious or worse ozone nonattainment, or 
as moderate or serious CO nonattainment with a design value greater than 
12.7 ppm, and having a 1980 Bureau of Census-defined

[[Page 329]]

(Census-defined) urbanized area population of 200,000 or more, shall 
implement enhanced I/M in the 1990 Census-defined urbanized area.
    (3) Any area classified, as of November 5, 1992, as marginal ozone 
nonattainment or moderate CO nonattainment with a design value of 12.7 
ppm or less shall continue operating I/M programs that were part of an 
approved State Implementation Plan (SIP) as of November 15, 1990, and 
shall update those programs as necessary to meet the basic I/M program 
requirements of this subpart. Any such area required by the Clean Air 
Act, as in effect prior to November 15, 1990, as interpreted in EPA 
guidance, to have an I/M program shall also implement a basic I/M 
program. Serious, severe and extreme ozone areas and CO areas over 12.7 
ppm shall also continue operating existing I/M programs and shall 
upgrade such programs, as appropriate, pursuant to this subpart.
    (4) Any area classified as moderate ozone nonattainment, and not 
required to implement enhanced I/M under paragraph (a)(1) of this 
section, shall implement basic I/M in any 1990 Census-defined urbanized 
area with a population of 200,000 or more.
    (5) [Reserved]
    (6) If the boundaries of a moderate ozone nonattainment area are 
changed pursuant to section 107(d)(4)(A)(i)-(ii) of the Clean Air Act, 
such that the area includes additional urbanized areas with a population 
of 200,000 or more, then a basic I/M program shall be implemented in 
these additional urbanized areas.
    (7) If the boundaries of a serious or worse ozone nonattainment area 
or of a moderate or serious CO nonattainment area with a design value 
greater than 12.7 ppm are changed any time after enactment pursuant to 
section 107(d)(4)(A) such that the area includes additional urbanized 
areas, then an enhanced I/M program shall be implemented in the newly 
included 1990 Census-defined urbanized areas, if the 1980 Census-defined 
urban area population is 200,000 or more.
    (8) If a marginal ozone nonattainment area, not required to 
implement enhanced I/M under paragraph (a)(1) of this section, is 
reclassified to moderate, a basic I/M program shall be implemented in 
the 1990 Census-defined urbanized area(s) with a population of 200,000 
or more. If the area is reclassified to serious or worse, an enhanced I/
M program shall be implemented in the 1990 Census-defined urbanized 
area, if the 1980 Census-defined urban area population is 200,000 or 
more.
    (9) If a moderate ozone or CO nonattainment area is reclassified to 
serious or worse, an enhanced I/M program shall be implemented in the 
1990 Census-defined urbanized area, if the 1980 Census-defined 
population is 200,000 or more.
    (b) Extent of area coverage. (1) In an ozone transport region, the 
program shall cover all counties within subject MSAs or subject portions 
of MSAs, as defined by OMB in 1990, except largely rural counties having 
a population density of less than 200 persons per square mile based on 
the 1990 Census and counties with less than 1% of the population in the 
MSA may be excluded provided that at least 50% of the MSA population is 
included in the program. This provision does not preclude the voluntary 
inclusion of portions of an excluded county. Non-urbanized islands not 
connected to the mainland by roads, bridges, or tunnels may be excluded 
without regard to population.
    (2) Outside of ozone transport regions, programs shall nominally 
cover at least the entire urbanized area, based on the 1990 census. 
Exclusion of some urban population is allowed as long as an equal number 
of non-urban residents of the MSA containing the subject urbanized area 
are included to compensate for the exclusion.
    (3) Emission reduction benefits from expanding coverage beyond the 
minimum required urban area boundaries can be applied toward the 
reasonable further progress requirements or can be used for offsets, 
provided the covered vehicles are operated in the nonattainment area, 
but not toward the enhanced I/M performance standard requirement.
    (4) In a multi-state urbanized area with a population of 200,000 or 
more that is required under paragraph (a) of this section to implement 
I/M, any State with a portion of the area having a 1990 Census-defined 
population of

[[Page 330]]

50,000 or more shall implement an I/M program. The other coverage 
requirements in paragraph (b) of this section shall apply in multi-state 
areas as well.
    (5) Notwithstanding the limitation in paragraph (b)(3) of this 
section, in an ozone transport region, States which opt for a program 
which meets the performance standard described in Sec. 51.351(h) and 
claim in their SIP less emission reduction credit than the basic 
performance standard for one or more pollutants, may apply a geographic 
bubble covering areas in the State not otherwise subject to an I/M 
requirement to achieve emission reductions from other measures equal to 
or greater than what would have been achieved if the low enhanced 
performance standard were met in the subject I/M areas. Emissions 
reductions from non-I/M measures shall not be counted towards the OTR 
low enhanced performance standard.
    (c) Requirements after attainment. All I/M programs shall provide 
that the program will remain effective, even if the area is redesignated 
to attainment status or the standard is otherwise rendered no longer 
applicable, until the State submits and EPA approves a SIP revision 
which convincingly demonstrates that the area can maintain the relevant 
standard(s) without benefit of the emission reductions attributable to 
the I/M program. The State shall commit to fully implement and enforce 
the program until such a demonstration can be made and approved by EPA. 
At a minimum, for the purposes of SIP approval, legislation authorizing 
the program shall not sunset prior to the attainment deadline for the 
applicable National Ambient Air Quality Standards (NAAQS).
    (d) SIP requirements. The SIP shall describe the applicable areas in 
detail and, consistent with Sec. 51.372 of this subpart, shall include 
the legal authority or rules necessary to establish program boundaries.

[57 FR 52987, Nov. 5, 1992, as amended at 60 FR 48034, Sept. 18, 1995; 
61 FR 39036, July 25, 1996; 65 FR 45532, July 24, 2000]



Sec. 51.351  Enhanced I/M performance standard.

    (a) [Reserved]
    (b) On-road testing. The performance standard shall include on-road 
testing (including out-of-cycle repairs in the case of confirmed 
failures) of at least 0.5% of the subject vehicle population, or 20,000 
vehicles whichever is less, as a supplement to the periodic inspection 
required in paragraphs (f), (g), and (h) of this section. Specific 
requirements are listed in Sec. 51.371 of this subpart.
    (c) On-board diagnostics (OBD). For those areas required to 
implement an enhanced I/M program prior to the effective date of 
designation and classifications under the 8-hour ozone standard, the 
performance standard shall include inspection of all model year 1996 and 
later light-duty vehicles and light-duty trucks equipped with certified 
on-board diagnostic systems, and repair of malfunctions or system 
deterioration identified by or affecting OBD systems as specified in 
Sec. 51.357, and assuming a start date of 2002 for such testing. For 
areas required to implement enhanced I/M as a result of designation and 
classification under the 8-hour ozone standard, the performance standard 
defined in paragraph (i) of this section shall include inspection of all 
model year 2001 and later light-duty vehicles and light-duty trucks 
equipped with certified on-board diagnostic systems, and repair of 
malfunctions or system deterioration identified by or affecting OBD 
systems as specified in Sec. 51.357, and assuming a start date of 4 
years after the effective date of designation and classification under 
the 8-hour ozone standard.
    (d) Modeling requirements. Equivalency of the emission levels which 
will be achieved by the I/M program design in the SIP to those of the 
model program described in this section shall be demonstrated using the 
most current version of EPA's mobile source emission model, or an 
alternative approved by the Administrator, using EPA guidance to aid in 
the estimation of input parameters. States may adopt alternative 
approaches that meet this performance standard. States may do so through 
program design changes that affect normal I/M input parameters to the 
mobile source emission factor model, or through program changes (such as 
the accelerated retirement of high emitting vehicles) that reduce in-

[[Page 331]]

use mobile source emissions. If the Administrator finds, under section 
182(b)(1)(A)(i) of the Act pertaining to reasonable further progress 
demonstrations or section 182(f)(1) of the Act pertaining to provisions 
for major stationary sources, that NOX emission reductions 
are not beneficial in a given ozone nonattainment area, then 
NOX emission reductions are not required of the enhanced I/M 
program, but the program shall be designed to offset NOX 
increases resulting from the repair of HC and CO failures.
    (e) [Reserved]
    (f) High Enhanced Performance Standard. Enhanced I/M programs shall 
be designed and implemented to meet or exceed a minimum performance 
standard, which is expressed as emission levels in area-wide average 
grams per mile (gpm), achieved from highway mobile sources as a result 
of the program. The emission levels achieved by the State's program 
design shall be calculated using the most current version, at the time 
of submittal, of the EPA mobile source emission factor model or an 
alternative model approved by the Administrator, and shall meet the 
minimum performance standard both in operation and for SIP approval. 
Areas shall meet the performance standard for the pollutants which cause 
them to be subject to enhanced I/M requirements. In the case of ozone 
nonattainment areas subject to enhanced I/M and subject areas in the 
Ozone Transport Region, the performance standard must be met for both 
oxides of nitrogen (NOx) and volatile organic compounds (VOCs), except 
as provided in paragraph (d) of this section. Except as provided in 
paragraphs (g) and (h) of this section, the model program elements for 
the enhanced I/M performance standard shall be as follows:
    (1) Network type. Centralized testing.
    (2) Start date. For areas with existing I/M programs, 1983. For 
areas newly subject, 1995.
    (3) Test frequency. Annual testing.
    (4) Model year coverage. Testing of 1968 and later vehicles.
    (5) Vehicle type coverage. Light duty vehicles, and light duty 
trucks, rated up to 8,500 pounds Gross Vehicle Weight Rating (GVWR).
    (6) Exhaust emission test type. Transient mass-emission testing on 
1986 and later model year vehicles using the IM240 driving cycle, two-
speed testing (as described in appendix B of this subpart S) of 1981-
1985 vehicles, and idle testing (as described in appendix B of this 
subpart S) of pre-1981 vehicles is assumed.
    (7) Emission standards. (i) Emission standards for 1986 through 1993 
model year light duty vehicles, and 1994 and 1995 light-duty vehicles 
not meeting Tier 1 emission standards, of 0.80 gpm hydrocarbons (HC), 20 
gpm CO, and 2.0 gpm NOX;
    (ii) Emission standards for 1986 through 1993 light duty trucks less 
than 6000 pounds gross vehicle weight rating (GVWR), and 1994 and 1995 
trucks not meeting Tier 1 emission standards, of 1.2 gpm HC, 20 gpm CO, 
and 3.5 gpm NOX;
    (iii) Emission standards for 1986 through 1993 light duty trucks 
greater than 6000 pounds GVWR, and 1994 and 1995 trucks not meeting the 
Tier 1 emission standards, of 1.2 gpm HC, 20 gpm CO, and 3.5 gpm 
NOX;
    (iv) Emission standards for 1994 and later light duty vehicles 
meeting Tier 1 emission standards of 0.70 gpm HC, 15 gpm CO, and 1.4 gpm 
NOX;
    (v) Emission standards for 1994 and later light duty trucks under 
6000 pounds GVWR and meeting Tier 1 emission standards of 0.70 gpm HC, 
15 gpm CO, and 2.0 gpm NOX;
    (vi) Emission standards for 1994 and later light duty trucks greater 
than 6000 pounds GVWR and meeting Tier 1 emission standards of 0.80 gpm 
HC, 15 gpm CO and 2.5 gpm NOX;
    (vii) Emission standards for 1981-1985 model year vehicles of 1.2% 
CO, and 220 gpm HC for the idle, two-speed tests and loaded steady-state 
tests (as described in appendix B of this subpart S); and
    (viii) Maximum exhaust dilution measured as no less than 6% CO plus 
carbon dioxide (CO2) on vehicles subject to a steady-state 
test (as described in appendix B of this subpart S); and
    (viii) Maximum exhaust dilution measured as no less than 6% CO plus 
carbon dioxide (CO2) on vehicles subject to a steady-state 
test (as described in appendix B of this subpart S).

[[Page 332]]

    (8) Emission control device inspections. (i) Visual inspection of 
the catalyst and fuel inlet restrictor on all 1984 and later model year 
vehicles.
    (ii) Visual inspection of the positive crankcase ventilation valve 
on 1968 through 1971 model years, inclusive, and of the exhaust gas 
recirculation valve on 1972 through 1983 model year vehicles, inclusive.
    (9) Evaporative system function checks. Evaporative system integrity 
(pressure) test on 1983 and later model year vehicles and an evaporative 
system transient purge test on 1986 and later model year vehicles.
    (10) Stringency. A 20% emission test failure rate among pre-1981 
model year vehicles.
    (11) Waiver rate. A 3% waiver rate, as a percentage of failed 
vehicles.
    (12) Compliance rate. A 96% compliance rate.
    (13) Evaluation date. Enhanced I/M program areas subject to the 
provisions of this paragraph shall be shown to obtain the same or lower 
emission levels as the model program described in this paragraph by 
January 1, 2002 to within 0.02 gpm. Subject 
programs shall demonstrate through modeling the ability to maintain this 
level of emission reduction (or better) through their attainment 
deadline for the applicable NAAQS standard(s).
    (g) Alternate Low Enhanced I/M Performance Standard. An enhanced I/M 
area which is either not subject to or has an approved State 
Implementation Plan pursuant to the requirements of the Clean Air Act 
Amendments of 1990 for Reasonable Further Progress in 1996, and does not 
have a disapproved plan for Reasonable Further Progress for the period 
after 1996 or a disapproved plan for attainment of the air quality 
standards for ozone or CO, may select the alternate low enhanced I/M 
performance standard described below in lieu of the standard described 
in paragraph (f) of this section. The model program elements for this 
alternate low enhanced I/M performance standard are:
    (1) Network type. Centralized testing.
    (2) Start date. For areas with existing I/M programs, 1983. For 
areas newly subject, 1995.
    (3) Test frequency. Annual testing.
    (4) Model year coverage. Testing of 1968 and newer vehicles.
    (5) Vehicle type coverage. Light duty vehicles, and light duty 
trucks, rated up to 8,500 pounds GVWR.
    (6) Exhaust emission test type. Idle testing of all covered vehicles 
(as described in appendix B of subpart S).
    (7) Emission standards. Those specified in 40 CFR part 85, subpart 
W.
    (8) Emission control device inspections. Visual inspection of the 
positive crankcase ventilation valve on all 1968 through 1971 model year 
vehicles, inclusive, and of the exhaust gas recirculation valve on all 
1972 and newer model year vehicles.
    (9) Evaporative system function checks. None.
    (10) Stringency. A 20% emission test failure rate among pre-1981 
model year vehicles.
    (11) Waiver rate. A 3% waiver rate, as a percentage of failed 
vehicles.
    (12) Compliance rate. A 96% compliance rate.
    (13) Evaluation date. Enhanced I/M program areas subject to the 
provisions of this paragraph (g) shall be shown to obtain the same or 
lower emission levels as the model program described in this paragraph 
by January 1, 2002 to within 0.02 gpm. Subject 
programs shall demonstrate through modeling the ability to maintain this 
level of emission reduction (or better) through their attainment 
deadline for the applicable NAAQS standard(s).
    (h) Ozone Transport Region Low-Enhanced Performance Standard. An 
attainment area, marginal ozone area, or moderate ozone area with a 1980 
Census population of less than 200,000 in the urbanized area, in an 
ozone transport region, that is required to implement enhanced I/M under 
section 184(b)(1)(A) of the Clean Air Act, but was not previously 
required to or did not in fact implement basic I/M under the Clean Air 
Act as enacted prior to 1990 and is not subject to the requirements for 
basic I/M programs in this subpart, may select the performance standard 
described below in lieu of the standard described in paragraph (f) or 
(g) of this section as long as the difference in emission reductions 
between the program described in paragraph (g) and this paragraph are 
made up with other

[[Page 333]]

measures, as provided in Sec. 51.350(b)(5). Offsetting measures shall 
not include those otherwise required by the Clean Air Act in the areas 
from which credit is bubbled. The program elements for this alternate 
OTR enhanced I/M performance standard are:
    (1) Network type. Centralized testing.
    (2) Start date. January 1, 1999.
    (3) Test frequency. Annual testing.
    (4) Model year coverage. Testing of 1968 and newer vehicles.
    (5) Vehicle type coverage. Light duty vehicles, and light duty 
trucks, rated up to 8,500 pounds GVWR.
    (6) Exhaust emission test type. Remote sensing measurements on 1968-
1995 vehicles; on-board diagnostic system checks on 1996 and newer 
vehicles.
    (7) Emission standards. For remote sensing measurements, a carbon 
monoxide standard of 7.5% (with at least two separate readings above 
this level to establish a failure).
    (8) Emission control device inspections. Visual inspection of the 
catalytic converter on 1975 and newer vehicles and visual inspection of 
the positive crankcase ventilation valve on 1968-1974 vehicles.
    (9) Waiver rate. A 3% waiver rate, as a percentage of failed 
vehicles.
    (10) Compliance rate. A 96% compliance rate.
    (11) Evaluation date. Enhanced I/M program areas subject to the 
provisions of this paragraph shall be shown to obtain the same or lower 
VOC and NOx emission levels as the model program described in this 
paragraph (h) by January 1, 2002 to within 0.02 
gpm. Subject programs shall demonstrate through modeling the ability to 
maintain this level of emission reduction (or better) through their 
attainment deadline for the applicable NAAQS standard(s). Equality of 
substituted emission reductions to the benefits of the low enhanced 
performance standard must be demonstrated for the same evaluation date.
    (i) Enhanced performance standard for areas designated and 
classified under the 8-hour ozone standard. Areas required to implement 
an enhanced I/M program as a result of being designated and classified 
under the 8-hour ozone standard, must meet or exceed the HC and 
NOX emission reductions achieved by the model program defined 
as follows:
    (1) Network type. Centralized testing.
    (2) Start date. 4 years after the effective date of designation and 
classification under the 8-hour ozone standard.
    (3) Test frequency. Annual testing.
    (4) Model year coverage. Testing of 1968 and newer vehicles.
    (5) Vehicle type coverage. Light duty vehicles, and light duty 
trucks, rated up to 8,500 pounds GVWR.
    (6) Emission test type. Idle testing (as described in appendix B of 
this subpart) for 1968-2000 vehicles; onboard diagnostic checks on 2001 
and newer vehicles.
    (7) Emission standards. Those specified in 40 CFR part 85, subpart 
W.
    (8) Emission control device inspections. Visual inspection of the 
positive crankcase ventilation valve on all 1968 through 1971 model year 
vehicles, inclusive, and of the exhaust gas recirculation valve on all 
1972 and newer model year vehicles.
    (9) Evaporative system function checks. None, with the exception of 
those performed by the OBD system on vehicles so-equipped and only for 
model year 2001 and newer vehicles.
    (10) Stringency. A 20% emission test failure rate among pre-1981 
model year vehicles.
    (11) Waiver rate. A 3% waiver rate, as a percentage of failed 
vehicles.
    (12) Compliance rate. A 96% compliance rate.
    (13) Evaluation date. Enhanced I/M program areas subject to the 
provisions of this paragraph (i) shall be shown to obtain the same or 
lower emission levels for HC and NOX as the model program 
described in this paragraph assuming an evaluation date set 6 years 
after the effective date of designation and classification under the 8-
hour ozone standard (rounded to the nearest July) to within 0.02 gpm. Subject programs shall demonstrate through 
modeling the ability to maintain this percent level of emission 
reduction (or

[[Page 334]]

better) through their applicable attainment date for the 8-hour ozone 
standard, also rounded to the nearest July.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993; 59 
FR 32343, June 23, 1994; 60 FR 48035, Sept. 18, 1995; 61 FR 39036, July 
25, 1996; 61 FR 40945, Aug. 6, 1996; 63 FR 24433, May 4, 1998; 65 FR 
45532, July 24, 2000; 66 FR 18176, Apr. 5, 2001; 71 FR 17710, Apr. 7, 
2006]



Sec. 51.352  Basic I/M performance standard.

    (a) Basic I/M programs shall be designed and implemented to meet or 
exceed a minimum performance standard, which is expressed as emission 
levels achieved from highway mobile sources as a result of the program. 
The performance standard shall be established using the following model 
I/M program inputs and local characteristics, such as vehicle mix and 
local fuel controls. Similarly, the emission reduction benefits of the 
State's program design shall be estimated using the most current version 
of the EPA mobile source emission model, and shall meet the minimum 
performance standard both in operation and for SIP approval.
    (1) Network type. Centralized testing.
    (2) Start date. For areas with existing I/M programs, 1983. For 
areas newly subject, 1994.
    (3) Test frequency. Annual testing.
    (4) Model year coverage. Testing of 1968 and later model year 
vehicles.
    (5) Vehicle type coverage. Light duty vehicles.
    (6) Exhaust emission test type. Idle test.
    (7) Emission standards. No weaker than specified in 40 CFR part 85, 
subpart W.
    (8) Emission control device inspections. None.
    (9) Stringency. A 20% emission test failure rate among pre-1981 
model year vehicles.
    (10) Waiver rate. A 0% waiver rate.
    (11) Compliance rate. A 100% compliance rate.
    (12) Evaluation date. Basic I/M programs shall be shown to obtain 
the same or lower emission levels as the model inputs by 1997 for ozone 
nonattainment areas and 1996 for CO nonattainment areas; and, for 
serious or worse ozone nonattainment areas, on each applicable milestone 
and attainment deadline, thereafter.
    (b) Oxides of nitrogen. Basic I/M testing in ozone nonattainment 
areas shall be designed such that no increase in NOX 
emissions occurs as a result of the program. If the Administrator finds, 
under section 182(b)(1)(A)(i) of the Act pertaining to reasonable 
further progress demonstrations or section 182(f)(1) of the Act 
pertaining to provisions for major stationary sources, that 
NOX emission reductions are not beneficial in a given ozone 
nonattainment area, then the basic I/M NOX requirement may be 
omitted. States shall implement any required NOX controls 
within 12 months of implementation of the program deadlines required in 
Sec. 51.373 of this subpart, except that newly implemented I/M programs 
shall include NOX controls from the start.
    (c) On-board diagnostics (OBD). For those areas required to 
implement a basic I/M program prior to the effective date of designation 
and classification under the 8-hour ozone standard, the performance 
standard shall include inspection of all model year 1996 and later 
light-duty vehicles equipped with certified on-board diagnostic systems, 
and repair of malfunctions or system deterioration identified by or 
affecting OBD systems as specified in Sec. 51.357, and assuming a start 
date of 2002 for such testing. For areas required to implement basic I/M 
as a result of designation and classification under the 8-hour ozone 
standard, the performance standard defined in paragraph (e) of this 
section shall include inspection of all model year 2001 and later light-
duty vehicles equipped with certified on-board diagnostic systems, and 
repair of malfunctions or system deterioration identified by or 
affecting OBD systems as specified in Sec. 51.357, and assuming a start 
date of 4 years after the effective date of designation and 
classification under the 8-hour ozone standard.
    (d) Modeling requirements. Equivalency of emission levels which will 
be achieved by the I/M program design in the SIP to those of the model 
program described in this section shall be demonstrated using the most 
current version of EPA's mobile source emission model and EPA guidance 
on the estimation of input parameters. Areas

[[Page 335]]

required to implement basic I/M programs shall meet the performance 
standard for the pollutants which cause them to be subject to basic 
requirements. Areas subject as a result of ozone nonattainment shall 
meet the standard for VOCs and shall demonstrate no NOX 
increase, as required in paragraph (b) of this section.
    (e) Basic performance standard for areas designated non-attainment 
for the 8-hour ozone standard. Areas required to implement a basic I/M 
program as a result of being designated and classified under the 8-hour 
ozone standard, must meet or exceed the emission reductions achieved by 
the model program defined for the applicable ozone precursor(s):
    (1) Network type. Centralized testing.
    (2) Start date. 4 years after the effective date of designation and 
classification under the 8-hour ozone standard.
    (3) Test frequency. Annual testing.
    (4) Model year coverage. Testing of 1968 and newer vehicles.
    (5) Vehicle type coverage. Light duty vehicles.
    (6) Emission test type. Idle testing (as described in appendix B of 
this subpart) for 1968-2000 vehicles; onboard diagnostic checks on 2001 
and newer vehicles.
    (7) Emission standards. Those specified in 40 CFR part 85, subpart 
W.
    (8) Emission control device inspections. None.
    (9) Evaporative system function checks. None, with the exception of 
those performed by the OBD system on vehicles so-equipped and only for 
model year 2001 and newer vehicles.
    (10) Stringency. A 20% emission test failure rate among pre-1981 
model year vehicles.
    (11) Waiver rate. A 0% waiver rate, as a percentage of failed 
vehicles.
    (12) Compliance rate. A 100% compliance rate.
    (13) Evaluation date. Basic I/M program areas subject to the 
provisions of this paragraph (e) shall be shown to obtain the same or 
lower emission levels as the model program described in this paragraph 
by an evaluation date set 6 years after the effective date of 
designation and classification under the 8-hour ozone standard (rounded 
to the nearest July) for the applicable ozone precursor(s).

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996; 63 
FR 24433, May 4, 1998; 66 FR 18177, Apr. 5, 2001; 71 FR 17711, Apr. 7, 
2006]



Sec. 51.353  Network type and program evaluation.

    Basic and enhanced I/M programs can be centralized, decentralized, 
or a hybrid of the two at the State's discretion, but shall be 
demonstrated to achieve the same (or better) level of emission reduction 
as the applicable performance standard described in either Sec. 51.351 
or 51.352 of this subpart. For decentralized programs other than those 
meeting the design characteristics described in paragraph (a) of this 
section, the State must demonstrate that the program is achieving the 
level of effectiveness claimed in the plan within 12 months of the 
plan's final conditional approval before EPA can convert that approval 
to a final full approval. The adequacy of these demonstrations will be 
judged by the Administrator on a case-by-case basis through notice-and-
comment rulemaking.
    (a) Presumptive equivalency. A decentralized network consisting of 
stations that only perform official I/M testing (which may include 
safety-related inspections) and in which owners and employees of those 
stations, or companies owning those stations, are contractually or 
legally barred from engaging in motor vehicle repair or service, motor 
vehicle parts sales, and motor vehicle sale and leasing, either directly 
or indirectly, and are barred from referring vehicle owners to 
particular providers of motor vehicle repair services (except as 
provided in Sec. 51.369(b)(1) of this subpart) shall be considered 
presumptively equivalent to a centralized, test-only system including 
comparable test elements. States may allow such stations to engage in 
the full range of sales not covered by the above prohibition, including 
self-serve gasoline, pre-packaged oil, or other, non-automotive, 
convenience store items. At the State's discretion, such stations may 
also fulfill other functions typically carried out by the State such as 
renewal of vehicle registration and

[[Page 336]]

driver's licenses, or tax and fee collections.
    (b) [Reserved]
    (c) Program evaluation. Enhanced I/M programs shall include an 
ongoing evaluation to quantify the emission reduction benefits of the 
program, and to determine if the program is meeting the requirements of 
the Clean Air Act and this subpart.
    (1) The State shall report the results of the program evaluation on 
a biennial basis, starting two years after the initial start date of 
mandatory testing as required in Sec. 51.373 of this subpart.
    (2) The evaluation shall be considered in establishing actual 
emission reductions achieved from I/M for the purposes of satisfying the 
requirements of sections 182(g)(1) and 182(g)(2) of the Clean Air Act, 
relating to reductions in emissions and compliance demonstration.
    (3) The evaluation program shall consist, at a minimum, of those 
items described in paragraph (b)(1) of this section and program 
evaluation data using a sound evaluation methodology, as approved by 
EPA, and evaporative system checks, specified in Sec. 51.357(a) (9) and 
(10) of this subpart, for model years subject to those evaporative 
system test procedures. The test data shall be obtained from a 
representative, random sample, taken at the time of initial inspection 
(before repair) on a minimum of 0.1 percent of the vehicles subject to 
inspection in a given year. Such vehicles shall receive a State 
administered or monitored test, as specified in this paragraph (c)(3), 
prior to the performance of I/M-triggered repairs during the inspection 
cycle under consideration.
    (4) The program evaluation test data shall be submitted to EPA and 
shall be capable of providing accurate information about the overall 
effectiveness of an I/M program, such evaluation to begin no later than 
1 year after program start-up.
    (5) Areas that qualify for and choose to implement an OTR low 
enhanced I/M program, as established in Sec. 51.351(h), and that claim 
in their SIP less emission reduction credit than the basic performance 
standard for one or more pollutants, are exempt from the requirements of 
paragraphs (c)(1) through (c)(4) of this section. The reports required 
under Sec. 51.366 of this part shall be sufficient in these areas to 
satisfy the requirements of Clean Air Act for program reporting.
    (d) SIP requirements. (1) The SIP shall include a description of the 
network to be employed, the required legal authority, and, in the case 
of areas making claims under paragraph (b) of this section, the required 
demonstration.
    (2) The SIP shall include a description of the evaluation schedule 
and protocol, the sampling methodology, the data collection and analysis 
system, the resources and personnel for evaluation, and related details 
of the evaluation program, and the legal authority enabling the 
evaluation program.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993; 61 
FR 39037, July 25, 1996; 63 FR 1368, Jan. 9, 1998; 65 FR 45532, July 24, 
2000; 71 FR 17711, Apr. 7, 2006]



Sec. 51.354  Adequate tools and resources.

    (a) Administrative resources. The program shall maintain the 
administrative resources necessary to perform all of the program 
functions including quality assurance, data analysis and reporting, and 
the holding of hearings and adjudication of cases. A portion of the test 
fee or a separately assessed per vehicle fee shall be collected, placed 
in a dedicated fund and retained, to be used to finance program 
oversight, management, and capital expenditures. Alternatives to this 
approach shall be acceptable if the State can demonstrate that adequate 
funding of the program can be maintained in some other fashion (e.g., 
through contractual obligation along with demonstrated past 
performance). Reliance on future uncommitted annual or biennial 
appropriations from the State or local General Fund is not acceptable, 
unless doing otherwise would be a violation of the State's constitution. 
This section shall in no way require the establishment of a test fee if 
the State chooses to fund the program in some other manner.
    (b) Personnel. The program shall employ sufficient personnel to 
effectively carry out the duties related to the program, including but 
not limited to administrative audits, inspector audits,

[[Page 337]]

data analysis, program oversight, program evaluation, public education 
and assistance, and enforcement against stations and inspectors as well 
as against motorists who are out of compliance with program regulations 
and requirements.
    (c) Equipment. The program shall possess equipment necessary to 
achieve the objectives of the program and meet program requirements, 
including but not limited to a steady supply of vehicles for covert 
auditing, test equipment and facilities for program evaluation, and 
computers capable of data processing, analysis, and reporting. Equipment 
or equivalent services may be contractor supplied or owned by the State 
or local authority.
    (d) SIP requirements. The SIP shall include a description of the 
resources that will be used for program operation, and discuss how the 
performance standard will be met.
    (1) The SIP shall include a detailed budget plan which describes the 
source of funds for personnel, program administration, program 
enforcement, purchase of necessary equipment (such as vehicles for 
undercover audits), and any other requirements discussed throughout, for 
the period prior to the next biennial self-evaluation required in Sec. 
51.366 of this subpart.
    (2) The SIP shall include a description of personnel resources. The 
plan shall include the number of personnel dedicated to overt and covert 
auditing, data analysis, program administration, enforcement, and other 
necessary functions and the training attendant to each function.



Sec. 51.355  Test frequency and convenience.

    (a) The performance standards for I/M programs assume an annual test 
frequency; other schedules may be approved if the required emission 
targets are achieved. The SIP shall describe the test schedule in 
detail, including the test year selection scheme if testing is other 
than annual. The SIP shall include the legal authority necessary to 
implement and enforce the test frequency requirement and explain how the 
test frequency will be integrated with the enforcement process.
    (b) In enhanced I/M programs, test systems shall be designed in such 
a way as to provide convenient service to motorists required to get 
their vehicles tested. The SIP shall demonstrate that the network of 
stations providing test services is sufficient to insure short waiting 
times to get a test and short driving distances. Stations shall be 
required to adhere to regular testing hours and to test any subject 
vehicle presented for a test during its test period.



Sec. 51.356  Vehicle coverage.

    The performance standard for enhanced I/M programs assumes coverage 
of all 1968 and later model year light duty vehicles and light duty 
trucks up to 8,500 pounds GVWR, and includes vehicles operating on all 
fuel types. The standard for basic I/M programs does not include light 
duty trucks. Other levels of coverage may be approved if the necessary 
emission reductions are achieved. Vehicles registered or required to be 
registered within the I/M program area boundaries and fleets primarily 
operated within the I/M program area boundaries and belonging to the 
covered model years and vehicle classes comprise the subject vehicles.
    (a) Subject vehicles. (1) All vehicles of a covered model year and 
vehicle type shall be tested according to the applicable test schedule, 
including leased vehicles whose registration or titling is in the name 
of an equity owner other than the lessee or user.
    (2) All subject fleet vehicles shall be inspected. Fleets may be 
officially inspected outside of the normal I/M program test facilities, 
if such alternatives are approved by the program administration, but 
shall be subject to the same test requirements using the same quality 
control standards as non-fleet vehicles. If all vehicles in a particular 
fleet are tested during one part of the cycle, then the quality control 
requirements shall be met during the time of testing only. Any vehicle 
available for rent in the I/M area or for use in the I/M area shall be 
subject. Fleet vehicles not being tested in normal I/M test facilities 
in enhanced I/M programs, however, shall be inspected in

[[Page 338]]

independent, test-only facilities, according to the requirements of 
Sec. 51.353(a) of this subpart.
    (3) Subject vehicles which are registered in the program area but 
are primarily operated in another I/M area shall be tested, either in 
the area of primary operation, or in the area of registration. Alternate 
schedules may be established to permit convenient testing of these 
vehicles (e.g., vehicles belonging to students away at college should be 
rescheduled for testing during a visit home). I/M programs shall make 
provisions for providing official testing to vehicles registered 
elsewhere.
    (4) Vehicles which are operated on Federal installations located 
within an I/M program area shall be tested, regardless of whether the 
vehicles are registered in the State or local I/M area. This requirement 
applies to all employee-owned or leased vehicles (including vehicles 
owned, leased, or operated by civilian and military personnel on Federal 
installations) as well as agency-owned or operated vehicles, except 
tactical military vehicles, operated on the installation. This 
requirement shall not apply to visiting agency, employee, or military 
personnel vehicles as long as such visits do not exceed 60 calendar days 
per year. In areas without test fees collected in the lane, arrangements 
shall be made by the installation with the I/M program for reimbursement 
of the costs of tests provided for agency vehicles, at the discretion of 
the I/M agency. The installation shall provide documentation of proof of 
compliance to the I/M agency. The documentation shall include a list of 
subject vehicles and shall be updated periodically, as determined by the 
I/M program administrator, but no less frequently than each inspection 
cycle. The installation shall use one of the following methods to 
establish proof of compliance:
    (i) Presentation of a valid certificate of compliance from the local 
I/M program, from any other I/M program at least as stringent as the 
local program, or from any program deemed acceptable by the I/M program 
administrator.
    (ii) Presentation of proof of vehicle registration within the 
geographic area covered by the I/M program, except for any program whose 
enforcement is not through registration denial.
    (iii) Another method approved by the State or local I/M program 
administrator.
    (5) Special exemptions may be permitted for certain subject vehicles 
provided a demonstration is made that the performance standard will be 
met.
    (6) States may also exempt MY 1996 and newer OBD-equipped vehicles 
that receive an OBD-I/M inspection from the tailpipe, purge, and fill-
neck pressure tests (where applicable) without any loss of emission 
reduction credit.
    (b) SIP requirements. (1) The SIP shall include a detailed 
description of the number and types of vehicles to be covered by the 
program, and a plan for how those vehicles are to be identified, 
including vehicles that are routinely operated in the area but may not 
be registered in the area.
    (2) The SIP shall include a description of any special exemptions 
which will be granted by the program, and an estimate of the percentage 
and number of subject vehicles which will be impacted. Such exemptions 
shall be accounted for in the emission reduction analysis.
    (3) The SIP shall include the legal authority or rule necessary to 
implement and enforce the vehicle coverage requirement.

[57 FR 52987, Nov. 5, 1992, as amended at 66 FR 18177, Apr. 5, 2001]



Sec. 51.357  Test procedures and standards.

    Written test procedures and pass/fail standards shall be established 
and followed for each model year and vehicle type included in the 
program.
    (a) Test procedure requirements. Emission tests and functional tests 
shall be conducted according to good engineering practices to assure 
test accuracy.
    (1) Initial tests (i.e., those occurring for the first time in a 
test cycle) shall be performed without repair or adjustment at the 
inspection facility, prior to the test, except as provided in paragraph 
(a)(10)(i) of this section.
    (2) The vehicle owner or driver shall have access to the test area 
such that observation of the entire official inspection process on the 
vehicle is permitted. Such access may be limited but

[[Page 339]]

shall in no way prevent full observation.
    (3) An official test, once initiated, shall be performed in its 
entirety regardless of intermediate outcomes except in the case of 
invalid test condition, unsafe conditions, fast pass/fail algorithms, 
or, in the case of the on-board diagnostic (OBD) system check, unset 
readiness codes.
    (4) Tests involving measurement shall be performed with program-
approved equipment that has been calibrated according to the quality 
procedures contained in appendix A to this subpart.
    (5) Vehicles shall be rejected from testing if the exhaust system is 
missing or leaking, or if the vehicle is in an unsafe condition for 
testing. Coincident with mandatory OBD-I/M testing and repair of 
vehicles so equipped, MY 1996 and newer vehicles shall be rejected from 
testing if a scan of the OBD system reveals a ``not ready'' code for any 
component of the OBD system. At a state's option it may choose 
alternatively to reject MY 1996-2000 vehicles only if three or more 
``not ready'' codes are present and to reject MY 2001 and later model 
years only if two or more ``not ready'' codes are present. This 
provision does not release manufacturers from the obligations regarding 
readiness status set forth in 40 CFR 86.094-17(e)(1): ``Control of Air 
Pollution From New Motor Vehicles and New Motor Vehicle Engines: 
Regulations RequiringOn-Board Diagnostic Systems on 1994 and Later Model 
Year Light-Duty Vehicles and Light-Duty Trucks.'' Once the cause for 
rejection has been corrected, the vehicle must return for testing to 
continue the testing process. Failure to return for testing in a timely 
manner after rejection shall be considered non-compliance with the 
program, unless the motorist can prove that the vehicle has been sold, 
scrapped, or is otherwise no longer in operation within the program 
area.
    (6) Vehicles shall be retested after repair for any portion of the 
inspection that is failed on the previous test to determine if repairs 
were effective. To the extent that repair to correct a previous failure 
could lead to failure of another portion of the test, that portion shall 
also be retested. Evaporative system repairs shall trigger an exhaust 
emissions retest (in programs which conduct an exhaust emission test as 
part of the initial inspection).
    (7) Steady-state testing. Steady-state tests shall be performed in 
accordance with the procedures contained in appendix B to this subpart.
    (8) Emission control device inspection. Visual emission control 
device checks shall be performed through direct observation or through 
indirect observation using a mirror, video camera or other visual aid. 
These inspections shall include a determination as to whether each 
subject device is present and appears to be properly connected and 
appears to be the correct type for the certified vehicle configuration.
    (9) Evaporative system purge test procedure. The purge test 
procedure shall consist of measuring the total purge flow (in standard 
liters) occurring in the vehicle's evaporative system during the 
transient dynamometer emission test specified in paragraph (a)(11) of 
this section. The purge flow measurement system shall be connected to 
the purge portion of the evaporative system in series between the 
canister and the engine, preferably near the canister. The inspector 
shall be responsible for ensuring that all items that are disconnected 
in the conduct of the test procedure are properly re-connected at the 
conclusion of the test procedure. Alternative procedures may be used if 
they are shown to be equivalent or better to the satisfaction of the 
Administrator. Except in the case of government-run test facilities 
claiming sovereign immunity, any damage done to the evaporative emission 
control system during this test shall be repaired at the expense of the 
inspection facility.
    (10) Evaporative system integrity test procedure. The test sequence 
shall consist of the following steps:
    (i) Test equipment shall be connected to the fuel tank canister hose 
at the canister end. The gas cap shall be checked to ensure that it is 
properly, but not excessively tightened, and shall be tightened if 
necessary.

[[Page 340]]

    (ii) The system shall be pressurized to 14 0.5 
inches of water without exceeding 26 inches of water system pressure.
    (iii) Close off the pressure source, seal the evaporative system and 
monitor pressure decay for up to two minutes.
    (iv) Loosen the gas cap after a maximum of two minutes and monitor 
for a sudden pressure drop, indicating that the fuel tank was 
pressurized.
    (v) The inspector shall be responsible for ensuring that all items 
that are disconnected in the conduct of the test procedure are properly 
re-connected at the conclusion of the test procedure.
    (vi) Alternative procedures may be used if they are shown to be 
equivalent or better to the satisfaction of the Administrator. Except in 
the case of government-run test facilities claiming sovereign immunity, 
any damage done to the evaporative emission control system during this 
test shall be repaired at the expense of the inspection facility.
    (11) Transient emission test. The transient emission test shall 
consist of mass emission measurement using a constant volume sampler (or 
an Administrator-approved alternative methodology for accounting for 
exhaust volume) while the vehicle is driven through a computer-monitored 
driving cycle on a dynamometer. The driving cycle shall include 
acceleration, deceleration, and idle operating modes as specified in 
appendix E to this subpart (or an approved alternative). The driving 
cycle may be ended earlier using approved fast pass or fast fail 
algorithms and multiple pass/fail algorithms may be used during the test 
cycle to eliminate false failures. The transient test procedure, 
including algorithms and other procedural details, shall be approved by 
the Administrator prior to use in an I/M program.
    (12) On-board diagnostic checks. Beginning January 1, 2002, 
inspection of the on-board diagnostic (OBD) system on MY 1996 and newer 
light-duty vehicles and light-duty trucks shall be conducted according 
to the procedure described in 40 CFR 85.2222, at a minimum. This 
inspection may be used in lieu of tailpipe, purge, and fill-neck 
pressure testing. Alternatively, states may elect to phase-in OBD-I/M 
testing for one test cycle by using the OBD-I/M check to screen clean 
vehicles from tailpipe testing and require repair and retest for only 
those vehicles which proceed to fail the tailpipe test. An additional 
alternative is also available to states with regard to the deadline for 
mandatory testing, repair, and retesting of vehicles based upon the OBD-
I/M check. Under this third option, if a state can show good cause (and 
the Administrator takes notice-and-comment action to approve this good 
cause showing as a revision to the State's Implementation Plan), up to 
an additional 12 months' extensionmay be granted, establishing an 
alternative start date for such states of no later than January 1, 2003. 
States choosing to make this showing will also have available to them 
the phase-in approach described in this section, with the one-cycle time 
limit to begin coincident with the alternative start date established by 
Administrator approval of the showing, but no later than January 1, 
2003. The showing of good cause (and its approval or disapproval) will 
be addressed on a case-by-case basis by the Administrator.
    (13) Approval of alternative tests. Alternative test procedures may 
be approved if the Administrator finds that such procedures show a 
reasonable correlation with the Federal Test Procedure and are capable 
of identifying comparable emission reductions from the I/M program as a 
whole, in combination with other program elements, as would be 
identified by the test(s) which they are intended to replace.
    (b) Test standards--(1) Emissions standards. HC, CO, and CO + 
CO2 (or CO2 alone) emission standards shall be 
applicable to all vehicles subject to the program with the exception of 
MY 1996 and newer OBD-equipped light-duty vehicles and light-duty 
trucks, which will be held to the requirements of 40 CFR 85.2207, at a 
minimum. Repairs shall be required for failure of any standard 
regardless of the attainment status of the area. NOX emission 
standards shall be applied to vehicles subject to a loaded mode test in 
ozone nonattainment areas and in an ozone transport region, unless a 
waiver of NOX controls is provided to the State under Sec. 
51.351(d).

[[Page 341]]

    (2) Visual equipment inspection standards. (i) Vehicles shall fail 
visual inspections of subject emission control devices if such devices 
are part of the original certified configuration and are found to be 
missing, modified, disconnected, or improperly connected.
    (ii) Vehicles shall fail visual inspections of subject emission 
control devices if such devices are found to be incorrect for the 
certified vehicle configuration under inspection. Aftermarket parts, as 
well as original equipment manufacture parts, may be considered correct 
if they are proper for the certified vehicle configuration. Where an EPA 
aftermarket approval or self-certification program exists for a 
particular class of subject parts, vehicles shall fail visual equipment 
inspections if the part is neither original equipment manufacture nor 
from an approved or self-certified aftermarket manufacturer.
    (3) Functional test standards--(i) Evaporative system integrity 
test. Vehicles shall fail the evaporative system pressure test if the 
system cannot maintain a system pressure above eight inches of water for 
up to two minutes after being pressurized to 14 0.5 inches of water or if no pressure drop is detected 
when the gas cap is loosened as described in paragraph (a)(10)(iv) of 
this section. Additionally, vehicles shall fail the evaporative test if 
the canister is missing or obviously damaged, if hoses are missing or 
obviously disconnected, or if the gas cap is missing.
    (ii) Evaporative canister purge test. Vehicles with a total purge 
system flow measuring less than one liter, over the course of the 
transient test required in paragraph (a)(9) of this section, shall fail 
the evaporative purge test.
    (4) On-board diagnostic test standards. Vehicles shall fail the on-
board diagnostic test if they fail to meet the requirements of 40 CFR 
85.2207, at a minimum. Failure of the on-board diagnostic test need not 
result in failure of the vehicle inspection/maintenance test until 
January 1, 2002. Alternatively, states may elect to phase-in OBD-I/M 
testing for one test cycle by using the OBD- I/M check to screen clean 
vehicles from tailpipe testing and require repair and retest for only 
those vehicles which proceed to fail the tailpipe test. An additional 
alternative is also available to states with regard to the deadline for 
mandatory testing, repair, and retesting of vehicles based upon the OBD-
I/M check. Under this third option, if a state can show good cause (and 
the Administrator takes notice-and-comment action to approve this good 
cause showing), up to an additional 12 months' extension may be granted, 
establishing an alternative start date for such states of no later than 
January 1, 2003. States choosing to make this showing will also have 
available to them the phase-in approach described in this section, with 
the one-cycle time limit to begin coincident with the alternative start 
date established by Administrator approval of the showing, but no later 
than January 1, 2003. The showing of good cause (and its approval or 
disapproval) will be addressed on a case-by-case basis.
    (c) Fast test algorithms and standards. Special test algorithms and 
pass/fail algorithms may be employed to reduce test time when the test 
outcome is predictable with near certainty, if the Administrator 
approves by letter the equivalency to full procedure testing.
    (d) Applicability. In general, section 203(a)(3)(A) of the Clean Air 
Act prohibits altering a vehicle's configuration such that it changes 
from a certified to a non-certified configuration. In the inspection 
process, vehicles that have been altered from their original certified 
configuration are to be tested in the same manner as other subject 
vehicles with the exception of MY 1996 and newer, OBD-equipped vehicles 
on which the data link connector is missing, has been tampered with or 
which has been altered in such a way as to make OBD system testing 
impossible. Such vehicles shall be failed for the on-board diagnostics 
portion of the test and are expected to be repaired so that the vehicle 
is testable. Failure to return for retesting in a timely manner after 
failure and repair shall be considered non-compliance with the program, 
unless the motorist can prove that the vehicle has been sold, scrapped, 
or is otherwise no longer in operation within the program area.
    (1) Vehicles with engines other than the engine originally installed 
by the

[[Page 342]]

manufacturer or an identical replacement of such engine shall be subject 
to the test procedures and standards for the chassis type and model year 
including visual equipment inspections for all parts that are part of 
the original or now-applicable certified configuration and part of the 
normal inspection. States may choose to require vehicles with such 
engines to be subject to the test procedures and standards for the 
engine model year if it is newer than the chassis model year.
    (2) Vehicles that have been switched from an engine of one fuel type 
to another fuel type that is subject to the program (e.g., from a diesel 
engine to a gasoline engine) shall be subject to the test procedures and 
standards for the current fuel type, and to the requirements of 
paragraph (d)(1) of this section.
    (3) Vehicles that are switched to a fuel type for which there is no 
certified configuration shall be tested according to the most stringent 
emission standards established for that vehicle type and model year. 
Emission control device requirements may be waived if the program 
determines that the alternatively fueled vehicle configuration would 
meet the new vehicle standards for that model year without such devices.
    (4) Mixing vehicle classes (e.g., light-duty with heavy-duty) and 
certification types (e.g., California with Federal) within a single 
vehicle configuration shall be considered tampering.
    (e) SIP requirements. The SIP shall include a description of each 
test procedure used. The SIP shall include the rule, ordinance or law 
describing and establishing the test procedures.

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996; 63 
FR 24433, May 4, 1998; 65 FR 45533, July 24, 2000; 66 FR 18178, Apr. 5, 
2001]



Sec. 51.358  Test equipment.

    Computerized emission test systems are required for performing an 
official emissions test on subject vehicles.
    (a) Performance features of computerized emission test systems. The 
emission test equipment shall be certified by the program, and newly 
acquired emission test systems shall be subjected to acceptance test 
procedures to ensure compliance with program specifications.
    (1) Emission test equipment shall be capable of testing all subject 
vehicles and shall be updated from time to time to accommodate new 
technology vehicles as well as changes to the program. In the case of 
OBD-based testing, the equipment used to access the onboard computer 
shall be capable of testing all MY 1996 and newer, OBD-equipped light-
duty vehicles and light-duty trucks.
    (2) At a minimum, emission test equipment:
    (i) Shall make automatic pass/fail decisions;
    (ii) Shall be secured from tampering and/or abuse;
    (iii) Shall be based upon written specifications; and
    (iv) Shall be capable of simultaneously sampling dual exhaust 
vehicles in the case of tailpipe-based emission test equipment.
    (3) The vehicle owner or driver shall be provided with a record of 
test results, including all of the items listed in 40 CFR part 85, 
subpart W as being required on the test record (as applicable). The test 
report shall include:
    (i) A vehicle description, including license plate number, vehicle 
identification number, and odometer reading;
    (ii) The date and time of test;
    (iii) The name or identification number of the individual(s) 
performing the tests and the location of the test station and lane;
    (iv) The type(s) of test(s) performed;
    (v) The applicable test standards;
    (vi) The test results, by test, and, where applicable, by pollutant;
    (vii) A statement indicating the availability of warranty coverage 
as required in section 207 of the Clean Air Act;
    (viii) Certification that tests were performed in accordance with 
the regulations and, in the case of decentralized programs, the 
signature of the individual who performed the test; and
    (ix) For vehicles that fail the emission test, information on the 
possible cause(s) of the failure.
    (b) Functional characteristics of computerized emission test 
systems. The test system is composed of motor vehicle

[[Page 343]]

test equipment controlled by a computerized processor and shall make 
automatic pass/fail decisions.
    (1) [Reserved]
    (2) Test systems in enhanced I/M programs shall include a real-time 
data link to a host computer that prevents unauthorized multiple initial 
tests on the same vehicle in a test cycle and to insure test record 
accuracy. For areas which have demonstrated the ability to meet their 
other, non-I/M Clean Air Act requirements without relying on emission 
reductions from the I/M program (and which have also elected to employ 
stand-alone test equipment as part of the I/M program), such areas may 
adopt alternative methods for preventing multiple initial tests, subject 
to approval by the Administrator.
    (3) [Reserved]
    (4) On-board diagnostic test equipment requirements. The test 
equipment used to perform on-board diagnostic inspections shall function 
as specified in 40 CFR 85.2231.
    (c) SIP requirements. The SIP shall include written technical 
specifications for all test equipment used in the program and shall 
address each of the above requirements (as applicable). The 
specifications shall describe the testing process, the necessary test 
equipment, the required features, and written acceptance testing 
criteria and procedures.

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996; 65 
FR 45533, July 24, 2000; 66 FR 18178, Apr. 5, 2001]



Sec. 51.359  Quality control.

    Quality control measures shall insure that emission testing 
equipment is calibrated and maintained properly, and that inspection, 
calibration records, and control charts are accurately created, recorded 
and maintained (where applicable).
    (a) General requirements. (1) The practices described in this 
section and in appendix A to this subpart shall be followed for those 
tests (or portions of tests) which fall into the testing categories 
identified. Alternatives or exceptions to these procedures or 
frequencies may be approved by the Administrator based on a 
demonstration of comparable performance.
    (2) Preventive maintenance on all inspection equipment necessary to 
insure accurate and repeatable operation shall be performed on a 
periodic basis.
    (3) [Reserved]
    (b) Requirements for steady-state emissions testing equipment. (1) 
Equipment shall be maintained according to demonstrated good engineering 
practices to assure test accuracy. The calibration and adjustment 
requirements in appendix A to this subpart shall apply to all steady-
state test equipment. States may adjust calibration schedules and other 
quality control frequencies by using statistical process control to 
monitor equipment performance on an ongoing basis.
    (2) For analyzers that use ambient air as zero air, provision shall 
be made to draw the air from outside the inspection bay or lane in which 
the analyzer is situated.
    (3) The analyzer housing shall be constructed to protect the 
analyzer bench and electrical components from ambient temperature and 
humidity fluctuations that exceed the range of the analyzer's design 
specifications.
    (4) Analyzers shall automatically purge the analytical system after 
each test.
    (c) Requirements for transient exhaust emission test equipment. 
Equipment shall be maintained according to demonstrated good engineering 
practices to assure test accuracy. Computer control of quality assurance 
checks and quality control charts shall be used whenever possible. 
Exceptions to the procedures and the frequency of the checks described 
in appendix A of this subpart may be approved by the Administrator based 
on a demonstration of comparable performance.
    (d) Requirements for evaporative system functional test equipment. 
Equipment shall be maintained according to demonstrated good engineering 
practices to assure test accuracy. Computer control of quality assurance 
checks and quality control charts shall be used whenever possible. 
Exceptions to the procedures and the frequency of the checks described 
in appendix A of this subpart may be approved by the Administrator based 
on a demonstration of comparable performance.

[[Page 344]]

    (e) Document security. Measures shall be taken to maintain the 
security of all documents by which compliance with the inspection 
requirement is established including, but not limited to inspection 
certificates, waiver certificates, license plates, license tabs, and 
stickers. This section shall in no way require the use of paper 
documents but shall apply if they are used by the program for these 
purposes.
    (1) Compliance documents shall be counterfeit resistant. Such 
measures as the use of special fonts, water marks, ultra-violet inks, 
encoded magnetic strips, unique bar-coded identifiers, and difficult to 
acquire materials may be used to accomplish this requirement.
    (2) All inspection certificates, waiver certificates, and stickers 
shall be printed with a unique serial number and an official program 
seal.
    (3) Measures shall be taken to ensure that compliance documents 
cannot be stolen or removed without being damaged.
    (f) SIP requirements. The SIP shall include a description of quality 
control and record keeping procedures. The SIP shall include the 
procedure manual, rule, ordinance or law describing and establishing the 
quality control procedures and requirements.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993; 65 
FR 45533, July 24, 2000]



Sec. 51.360  Waivers and compliance via diagnostic inspection.

    The program may allow the issuance of a waiver, which is a form of 
compliance with the program requirements that allows a motorist to 
comply without meeting the applicable test standards, as long as the 
prescribed criteria described below are met.
    (a) Waiver issuance criteria. The waiver criteria shall include the 
following at a minimum.
    (1) Waivers shall be issued only after a vehicle has failed a retest 
performed after all qualifying repairs have been completed. Qualifying 
repairs include repairs of the emission control components, listed in 
paragraph (a)(5) of this section, performed within 60 days of the test 
date.
    (2) Any available warranty coverage shall be used to obtain needed 
repairs before expenditures can be counted towards the cost limits in 
paragraphs (a)(5) and (a)(6) of this section. The operator of a vehicle 
within the statutory age and mileage coverage under section 207(b) of 
the Clean Air Act shall present a written denial of warranty coverage 
from the manufacturer or authorized dealer for this provision to be 
waived for approved tests applicable to the vehicle.
    (3) Waivers shall not be issued to vehicles for tampering-related 
repairs. The cost of tampering-related repairs shall not be applicable 
to the minimum expenditure in paragraphs (a)(5) and (a)(6) of this 
section. States may issue exemptions for tampering-related repairs if it 
can be verified that the part in question or one similar to it is no 
longer available for sale.
    (4) Repairs shall be appropriate to the cause of the test failure, 
and a visual check shall be made to determine if repairs were actually 
made if, given the nature of the repair, it can be visually confirmed. 
Receipts shall be submitted for review to further verify that qualifying 
repairs were performed.
    (5) General repairs shall be performed by a recognized repair 
technician (i.e., one professionally engaged in vehicle repair, employed 
by a going concern whose purpose is vehicle repair, or possessing 
nationally recognized certification for emission-related diagnosis and 
repair) in order to qualify for a waiver. I/M programs may allow the 
cost of parts (not labor) utilized by non-technicians (e.g., owners) to 
apply toward the waiver limit. The waiver would apply to the cost of 
parts for the repair or replacement of the following list of emission 
control components: oxygen sensor, catalytic converter, thermal reactor, 
EGR valve, fuel filler cap, evaporative canister, PCV valve, air pump, 
distributor, ignition wires, coil, and spark plugs. The cost of any 
hoses, gaskets, belts, clamps, brackets or other accessories directly 
associated with these components may also be applied to the waiver 
limit.
    (6) In basic programs, a minimum of $75 for pre-81 vehicles and $200 
for 1981 and newer vehicles shall be spent in order to qualify for a 
waiver. These

[[Page 345]]

model year cutoffs and the associated dollar limits shall be in full 
effect by January 1, 1998, or coincident with program start-up, 
whichever is later. Prior to January 1, 1998, States may adopt any 
minimum expenditure commensurate with the waiver rate committed to for 
the purposes of modeling compliance with the basic I/M performance 
standard.
    (7) Beginning on January 1, 1998, enhanced I/M programs shall 
require the motorist to make an expenditure of at least $450 in repairs 
to qualify for a waiver. The I/M program shall provide that the $450 
minimum expenditure shall be adjusted in January of each year by the 
percentage, if any, by which the Consumer Price Index for the preceding 
calendar year differs from the Consumer Price Index of 1989. Prior to 
January 1, 1998, States may adopt any minimum expenditure commensurate 
with the waiver rate committed to for the purposes of modeling 
compliance with the relevant enhanced I/M performance standard.
    (i) The Consumer Price Index for any calendar year is the average of 
the Consumer Price Index for all-urban consumers published by the 
Department of Labor, as of the close of the 12-month period ending on 
August 31 of each calendar year. A copy of the current Consumer Price 
Index may be obtained from the Emission Planning and Strategies 
Division, U.S. Environmental Protection Agency, 2565 Plymouth Road, Ann 
Arbor, Michigan 48105.
    (ii) The revision of the Consumer Price Index which is most 
consistent with the Consumer Price Index for calendar year 1989 shall be 
used.
    (8) States may establish lower minimum expenditures if a program is 
established to scrap vehicles that do not meet standards after the lower 
expe nditure is made.
    (9) A time extension, not to exceed the period of the inspection 
frequency, may be granted to obtain needed repairs on a vehicle in the 
case of economic hardship when waiver requirements have not been met. 
After having received a time extension, a vehicle must fully pass the 
applicable test standards before becoming eligible for another time 
extension. The extension for a vehicle shall be tracked and reported by 
the program.
    (b) Compliance via diagnostic inspection. Vehicles subject to a 
transient IM240 emission test at the cutpoints established in Sec. Sec. 
51.351 (f)(7) and (g)(7) of this subpart may be issued a certificate of 
compliance without meeting the prescribed emission cutpoints, if, after 
failing a retest on emissions, a complete, documented physical and 
functional diagnosis and inspection performed by the I/M agency or a 
contractor to the I/M agency show that no additional emission-related 
repairs are needed. Any such exemption policy and procedures shall be 
subject to approval by the Administrator.
    (c) Quality control of waiver issuance. (1) Enhanced programs shall 
control waiver issuance and processing by establishing a system of 
agency-issued waivers. The State may delegate this authority to a single 
contractor but inspectors in stations and lanes shall not issue waivers. 
Basic programs may permit inspector-issued waivers as long as quality 
assurance efforts include a comprehensive review of waiver issuance.
    (2) The program shall include methods of informing vehicle owners or 
lessors of potential warranty coverage, and ways to obtain warranty 
repairs.
    (3) The program shall insure that repair receipts are authentic and 
cannot be revised or reused.
    (4) The program shall insure that waivers are only valid for one 
test cycle.
    (5) The program shall track, manage, and account for time extensions 
or exemptions so that owners or lessors cannot receive or retain a 
waiver improperly.
    (d) SIP requirements. (1) The SIP shall include a maximum waiver 
rate expressed as a percentage of initially failed vehicles. This waiver 
rate shall be used for estimating emission reduction benefits in the 
modeling analysis.
    (2) The State shall take corrective action if the waiver rate 
exceeds that committed to in the SIP or revise the SIP and the emission 
reductions claimed.
    (3) The SIP shall describe the waiver criteria and procedures, 
including cost

[[Page 346]]

limits, quality assurance methods and measures, and administration.
    (4) The SIP shall include the necessary legal authority, ordinance, 
or rules to issue waivers, set and adjust cost limits as required in 
paragraph (a)(5) of this section, and carry out any other functions 
necessary to administer the waiver system, including enforcement of the 
waiver provisions.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993; 60 
FR 48036, Sept. 18, 1995; 71 FR 17711, Apr. 7, 2006]



Sec. 51.361  Motorist compliance enforcement.

    Compliance shall be ensured through the denial of motor vehicle 
registration in enhanced I/M programs unless an exception for use of an 
existing alternative is approved. An enhanced I/M area may use an 
existing alternative if it demonstrates that the alternative has been 
more effective than registration denial. An enforcement mechanism may be 
considered an ``existing alternative'' only in States that, for some 
area in the State, had an I/M program with that mechanism in operation 
prior to passage of the 1990 Amendments to the Act. A basic I/M area may 
use an alternative enforcement mechanism if it demonstrates that the 
alternative will be as effective as registration denial. Two other types 
of enforcement programs may qualify for enhanced I/M programs if 
demonstrated to have been more effective than enforcement of the 
registration requirement in the past: Sticker-based enforcement programs 
and computer-matching programs. States that did not adopt an I/M program 
for any area of the State before November 15, 1990, may not use an 
enforcement alternative in connection with an enhanced I/M program 
required to be adopted after that date.
    (a) Registration denial. Registration denial enforcement is defined 
as rejecting an application for initial registration or reregistration 
of a used vehicle (i.e., a vehicle being registered after the initial 
retail sale and associated registration) unless the vehicle has complied 
with the I/M requirement prior to granting the application. Pursuant to 
section 207(g)(3) of the Act, nothing in this subpart shall be construed 
to require that new vehicles shall receive emission testing prior to 
initial retail sale. In designing its enforcement program, the State 
shall:
    (1) Provide an external, readily visible means of determining 
vehicle compliance with the registration requirement to facilitate 
enforcement of the program;
    (2) Adopt a schedule of testing (either annual or biennial) that 
clearly determines when a vehicle shall comply prior to registration;
    (3) Design a testing certification mechanism (either paper-based or 
electronic) that shall be used for registration purposes and clearly 
indicates whether the certification is valid for purposes of 
registration, including:
    (i) Expiration date of the certificate;
    (ii) Unambiguous vehicle identification information; and
    (iii) Whether the vehicle passed or received a waiver;
    (4) Routinely issue citations to motorists with expired or missing 
license plates, with either no registration or an expired registration, 
and with no license plate decals or expired decals, and provide for 
enforcement officials other than police to issue citations (e.g., 
parking meter attendants) to parked vehicles in noncompliance;
    (5) Structure the penalty system to deter non-compliance with the 
registration requirement through the use of mandatory minimum fines 
(meaning civil, monetary penalties, in this subpart) constituting a 
meaningful deterrent and through a requirement that compliance be 
demonstrated before a case can be closed;
    (6) Ensure that evidence of testing is available and checked for 
validity at the time of a new registration of a used vehicle or 
registration renewal;
    (7) Prevent owners or lessors from avoiding testing through 
manipulation of the title or registration system; title transfers may 
re-start the clock on the inspection cycle only if proof of current 
compliance is required at title transfer;
    (8) Prevent the fraudulent initial classification or 
reclassification of a vehicle from subject to non-subject or exempt by 
requiring proof of address changes prior to registration record 
modification, and documentation from

[[Page 347]]

the testing program (or delegate) certifying based on a physical 
inspection that the vehicle is exempt;
    (9) Limit and track the use of time extensions of the registration 
requirement to prevent repeated extensions;
    (10) Provide for meaningful penalties for cases of registration 
fraud;
    (11) Limit and track exemptions to prevent abuse of the exemption 
policy for vehicles claimed to be out-of-state; and
    (12) Encourage enforcement of vehicle registration transfer 
requirements when vehicle owners move into the I/M area by coordinating 
with local and State enforcement agencies and structuring other 
activities (e.g., drivers license issuance) to effect registration 
transfers.
    (b) Alternative enforcement mechanisms--(1) General requirements. 
The program shall demonstrate that a non-registration-based enforcement 
program is currently more effective than registration-denial enforcement 
in enhanced I/M programs or, prospectively, as effective as registration 
denial in basic programs. The following general requirements shall 
apply:
    (i) For enhanced I/M programs, the area in question shall have had 
an operating I/M program using the alternative mechanism prior to 
enactment of the Clean Air Act Amendments of 1990. While modifications 
to improve compliance may be made to the program that was in effect at 
the time of enactment, the expected change in effectiveness cannot be 
considered in determining acceptability;
    (ii) The State shall assess the alternative program's effectiveness, 
as well as the current effectiveness of the registration system, 
including the following:
    (A) Determine the number and percentage of vehicles subject to the 
I/M program that were in compliance with the program over the course of 
at least one test cycle; and
    (B) Determine the number and fraction of the same group of vehicles 
as in paragraph (b)(1)(ii)(A) of this section that were in compliance 
with the registration requirement over the same period. Late 
registration shall not be considered non-compliance for the purposes of 
this determination. The precise definition of late registration versus a 
non-complying vehicle shall be explained and justified in the SIP;
    (iii) An alternative mechanism shall be considered more effective if 
the fraction of vehicles complying with the existing program, as 
determined according to the requirements of this section, is greater 
than the fraction of vehicles complying with the registration 
requirement. An alternative mechanism is as effective if the fraction 
complying with the program is at least equal to the fraction complying 
with the registration requirement.
    (2) Sticker-based enforcement. In addition to the general 
requirements, a sticker-based enforcement program shall demonstrate that 
the enforcement mechanism will swiftly and effectively prevent operation 
of subject vehicles that fail to comply. Such demonstration shall 
include the following:
    (i) An assessment of the current extent of the following forms of 
non-compliance and demonstration that mechanisms exist to keep such non-
compliance within acceptable limits:
    (A) Use of stolen, counterfeit, or fraudulently obtained stickers;
    (B) In States with safety inspections, the use of ``Safety 
Inspection Only'' stickers on vehicles that should be subject to the I/M 
requirement as well; and
    (C) Operation of vehicles with expired stickers, including a 
stratification of non-compliance by length of noncompliance and model 
year.
    (ii) The program as currently implemented or as proposed to be 
improved shall also:
    (A) Require an easily observed external identifier such as the 
county name on the license plate, an obviously unique license plate tab, 
or other means that shows whether or not a vehicle is subject to the I/M 
requirement;
    (B) Require an easily observed external identifier, such as a 
windshield sticker or license plate tab that shows whether a subject 
vehicle is in compliance with the inspection requirement;
    (C) Impose monetary fines at least as great as the estimated cost of 
compliance with I/M requirements (e.g., test fee plus minimum waiver 
expenditure) for the absence of such identifiers;
    (D) Require that such identifiers be of a quality that makes them 
difficult

[[Page 348]]

to counterfeit, difficult to remove without destroying once installed, 
and durable enough to last until the next inspection without fading, 
peeling, or other deterioration;
    (E) Perform surveys in a variety of locations and at different times 
for the presence of the required identifiers such that at least 10% of 
the vehicles or 10,000 vehicles (whichever is less) in the subject 
vehicle population are sampled each year;
    (F) Track missing identifiers for all inspections performed at each 
station, with stations being held accountable for all such identifiers 
they are issued; and
    (G) Assess and collect significant fines for each identifier that is 
unaccounted for by a station.
    (3) Computer matching. In addition to the general requirements, 
computer-matching programs shall demonstrate that the enforcement 
mechanism will swiftly and effectively prevent operation of subject 
vehicles that fail to comply. Such demonstration shall:
    (i) Require an expeditious system that results in at least 90% of 
the subject vehicles in compliance within 4 months of the compliance 
deadline;
    (ii) Require that subject vehicles be given compliance deadlines 
based on the regularly scheduled test date, not the date of previous 
compliance;
    (iii) Require that motorists pay monetary fines at least as great as 
the estimated cost of compliance with I/M requirements (e.g., test fee 
plus minimum waiver expenditure) for the continued operation of a 
noncomplying vehicle beyond 4 months of the deadline;
    (iv) Require that continued non-compliance will eventually result in 
preventing operation of the non-complying vehicle (no later than the 
date of the next test cycle) through, at a minimum, suspension of 
vehicle registration and subsequent denial of reregistration;
    (v) Demonstrate that the computer system currently in use is 
adequate to store and manipulate the I/M vehicle database, generate 
computerized notices, and provide regular backup to said system while 
maintaining auxiliary storage devices to insure ongoing operation of the 
system and prevent data losses;
    (vi) Track each vehicle through the steps taken to ensure 
compliance, including:
    (A) The compliance deadline;
    (B) The date of initial notification;
    (C) The dates warning letters are sent to non-complying vehicle 
owners;
    (D) The dates notices of violation or other penalty notices are 
sent; and
    (E) The dates and outcomes of other steps in the process, including 
the final compliance date;
    (vii) Compile and report monthly summaries including statistics on 
the percentage of vehicles at each stage in the enforcement process; and
    (viii) Track the number and percentage of vehicles initially 
identified as requiring testing but which are never tested as a result 
of being junked, sold to a motorist in a non-I/M program area, or for 
some other reason.
    (c) SIP requirements. (1) The SIP shall provide information 
concerning the enforcement process, including:
    (i) A description of the existing compliance mechanism if it is to 
be used in the future and the demonstration that it is as effective or 
more effective than registration-denial enforcement;
    (ii) An identification of the agencies responsible for performing 
each of the applicable activities in this section;
    (iii) A description of and accounting for all classes of exempt 
vehicles; and
    (iv) A description of the plan for testing fleet vehicles, rental 
car fleets, leased vehicles, and any other subject vehicles, e.g., those 
operated in (but not necessarily registered in) the program area.
    (2) The SIP shall include a determination of the current compliance 
rate based on a study of the system that includes an estimate of 
compliance losses due to loopholes, counterfeiting, and unregistered 
vehicles. Estimates of the effect of closing such loopholes and 
otherwise improving the enforcement mechanism shall be supported with 
detailed analyses.
    (3) The SIP shall include the legal authority to implement and 
enforce the program.
    (4) The SIP shall include a commitment to an enforcement level to be

[[Page 349]]

used for modeling purposes and to be maintained, at a minimum, in 
practice.

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 49682, Sept. 23, 1996]



Sec. 51.362  Motorist compliance enforcement program oversight.

    The enforcement program shall be audited regularly and shall follow 
effective program management practices, including adjustments to improve 
operation when necessary.
    (a) Quality assurance and quality control. A quality assurance 
program shall be implemented to insure effective overall performance of 
the enforcement system. Quality control procedures are required to 
instruct individuals in the enforcement process regarding how to 
properly conduct their activities. At a minimum, the quality control and 
quality assurance program shall include:
    (1) Verification of exempt vehicle status by inspecting and 
confirming such vehicles by the program or its delegate;
    (2) Facilitation of accurate critical test data and vehicle 
identifier collection through the use of automatic data capture systems 
such as bar-code scanners or optical character readers, or through 
redundant data entry (where applicable);
    (3) Maintenance of an audit trail to allow for the assessment of 
enforcement effectiveness;
    (4) Establishment of written procedures for personnel directly 
engaged in I/M enforcement activities;
    (5) Establishment of written procedures for personnel engaged in I/M 
document handling and processing, such as registration clerks or 
personnel involved in sticker dispensing and waiver processing, as well 
as written procedures for the auditing of their performance;
    (6) Follow-up validity checks on out-of-area or exemption-triggering 
registration changes;
    (7) Analysis of registration-change applications to target potential 
violators;
    (8) A determination of enforcement program effectiveness through 
periodic audits of test records and program compliance documentation;
    (9) Enforcement procedures for disciplining, retraining, or removing 
enforcement personnel who deviate from established requirements, or in 
the case of non-government entities that process registrations, for 
defranchising, revoking or otherwise discontinuing the activity of the 
entity issuing registrations; and
    (10) The prevention of fraudulent procurement or use of inspection 
documents by controlling and tracking document distribution and 
handling, and making stations financially liable for missing or 
unaccounted for documents by assessing monetary fines reflecting the 
``street value'' of these documents (i.e., the test fee plus the minimum 
waiver expenditure).
    (b) Information management. In establishing an information base to 
be used in characterizing, evaluating, and enforcing the program, the 
State shall:
    (1) Determine the subject vehicle population;
    (2) Permit EPA audits of the enforcement process;
    (3) Assure the accuracy of registration and other program document 
files;
    (4) Maintain and ensure the accuracy of the testing database through 
periodic internal and/or third-party review;
    (5) Compare the testing database to the registration database to 
determine program effectiveness, establish compliance rates, and to 
trigger potential enforcement action against non-complying motorists; 
and
    (6) Sample the fleet as a determination of compliance through 
parking lot surveys, road-side pull-overs, or other in-use vehicle 
measurements.
    (c) SIP requirements. The SIP shall include a description of 
enforcement program oversight and information management activities.

[57 FR 52987, Nov. 5, 1992, as amended at 65 FR 45534, July 24, 2000]



Sec. 51.363  Quality assurance.

    An ongoing quality assurance program shall be implemented to 
discover, correct and prevent fraud, waste, and abuse and to determine 
whether procedures are being followed, are adequate, whether equipment 
is measuring accurately, and whether other problems

[[Page 350]]

might exist which would impede program performance. The quality 
assurance and quality control procedures shall be periodically evaluated 
to assess their effectiveness and relevance in achieving program goals.
    (a) Performance audits. Performance audits shall be conducted on a 
regular basis to determine whether inspectors are correctly performing 
all tests and other required functions. Performance audits shall be of 
two types: overt and covert, and shall include:
    (1) Performance audits based upon written procedures and results 
shall be reported using either electronic or written forms to be 
retained in the inspector and station history files, with sufficient 
detail to support either an administrative or civil hearing;
    (2) Performance audits in addition to regularly programmed audits 
for stations employing inspectors suspected of violating regulations as 
a result of audits, data analysis, or consumer complaints;
    (3) Overt performance audits shall be performed at least twice per 
year for each lane or test bay and shall include:
    (i) A check for the observance of appropriate document security;
    (ii) A check to see that required record keeping practices are being 
followed;
    (iii) A check for licenses or certificates and other required 
display information; and
    (iv) Observation and written evaluation of each inspector's ability 
to properly perform an inspection;
    (4) Covert performance audits shall include:
    (i) Remote visual observation of inspector performance, which may 
include the use of aids such as binoculars or video cameras, at least 
once per year per inspector in high-volume stations (i.e., those 
performing more than 4000 tests per year);
    (ii) Site visits at least once per year per number of inspectors 
using covert vehicles set to fail (this requirement sets a minimum level 
of activity, not a requirement that each inspector be involved in a 
covert audit);
    (iii) For stations that conduct both testing and repairs, at least 
one covert vehicle visit per station per year including the purchase of 
repairs and subsequent retesting if the vehicle is initially failed for 
tailpipe emissions (this activity may be accomplished in conjunction 
with paragraph (a)(4)(ii) of this section but must involve each station 
at least once per year);
    (iv) Documentation of the audit, including vehicle condition and 
preparation, sufficient for building a legal case and establishing a 
performance record;
    (v) Covert vehicles covering the range of vehicle technology groups 
(e.g., carbureted and fuel-injected vehicles) included in the program, 
including a full range of introduced malfunctions covering the emission 
test, the evaporative system tests, and emission control component 
checks (as applicable);
    (vi) Sufficient numbers of covert vehicles and auditors to allow for 
frequent rotation of both to prevent detection by station personnel; and
    (vii) Where applicable, access to on-line inspection databases by 
State personnel to permit the creation and maintenance of covert vehicle 
records.
    (b) Record audits. Station and inspector records shall be reviewed 
or screened at least monthly to assess station performance and identify 
problems that may indicate potential fraud or incompetence. Such review 
shall include:
    (1) Automated record analysis to identify statistical 
inconsistencies, unusual patterns, and other discrepancies;
    (2) Visits to inspection stations to review records not already 
covered in the electronic analysis (if any); and
    (3) Comprehensive accounting for all official forms that can be used 
to demonstrate compliance with the program.
    (c) Equipment audits. During overt site visits, auditors shall 
conduct quality control evaluations of the required test equipment, 
including (where applicable):
    (1) A gas audit using gases of known concentrations at least as 
accurate as those required for regular equipment quality control and 
comparing these concentrations to actual readings;
    (2) A check for tampering, worn instrumentation, blocked filters, 
and other conditions that would impede accurate sampling;

[[Page 351]]

    (3) A check for critical flow in critical flow CVS units;
    (4) A check of the Constant Volume Sampler flow calibration;
    (5) A check for the optimization of the Flame Ionization Detection 
fuel-air ratio using methane;
    (6) A leak check;
    (7) A check to determine that station gas bottles used for 
calibration purposes are properly labelled and within the relevant 
tolerances;
    (8) Functional dynamometer checks addressing coast-down, roll speed 
and roll distance, inertia weight selection, and power absorption;
    (9) A check of the system's ability to accurately detect background 
pollutant concentrations;
    (10) A check of the pressure monitoring devices used to perform the 
evaporative canister pressure test(s); and
    (11) A check of the purge flow metering system.
    (d) Auditor training and proficiency. (1) Auditors shall be formally 
trained and knowledgeable in:
    (i) The use of test equipment and/or procedures;
    (ii) Program rules and regulations;
    (iii) The basics of air pollution control;
    (iv) Basic principles of motor vehicle engine repair, related to 
emission performance;
    (v) Emission control systems;
    (vi) Evidence gathering;
    (vii) State administrative procedures laws;
    (viii) Quality assurance practices; and
    (ix) Covert audit procedures.
    (2) Auditors shall themselves be audited at least once annually.
    (3) The training and knowledge requirements in paragraph (d)(1) of 
this section may be waived for temporary auditors engaged solely for the 
purpose of conducting covert vehicle runs.
    (e) SIP requirements. The SIP shall include a description of the 
quality assurance program, and written procedures manuals covering both 
overt and covert performance audits, record audits, and equipment 
audits. This requirement does not include materials or discussion of 
details of enforcement strategies that would ultimately hamper the 
enforcement process.

[57 FR 52987, Nov. 5, 1992, as amended at 65 FR 45534, July 24, 2000]



Sec. 51.364  Enforcement against contractors, stations and inspectors.

    Enforcement against licensed stations or contractors, and inspectors 
shall include swift, sure, effective, and consistent penalties for 
violation of program requirements.
    (a) Imposition of penalties. A penalty schedule shall be developed 
that establishes minimum penalties for violations of program rules and 
procedures.
    (1) The schedule shall categorize and list violations and the 
minimum penalties to be imposed for first, second, and subsequent 
violations and for multiple violation of different requirements. In the 
case of contracted systems, the State may use compensation retainage in 
lieu of penalties.
    (2) Substantial penalties or retainage shall be imposed on the first 
offense for violations that directly affect emission reduction benefits. 
At a minimum, in test-and-repair programs inspector and station license 
suspension shall be imposed for at least 6 months whenever a vehicle is 
intentionally improperly passed for any required portion of the test. In 
test-only programs, inspectors shall be removed from inspector duty for 
at least 6 months (or a retainage penalty equivalent to the inspector's 
salary for that period shall be imposed).
    (3) All findings of serious violations of rules or procedural 
requirements shall result in mandatory fines or retainage. In the case 
of gross neglect, a first offense shall result in a fine or retainage of 
no less than $100 or 5 times the inspection fee, whichever is greater, 
for the contractor or the licensed station, and the inspector if 
involved.
    (4) Any finding of inspector incompetence shall result in mandatory 
training before inspection privileges are restored.
    (5) License or certificate suspension or revocation shall mean the 
individual is barred from direct or indirect involvement in any 
inspection operation during the term of the suspension or revocation.

[[Page 352]]

    (b) Legal authority. (1) The quality assurance officer shall have 
the authority to temporarily suspend station and inspector licenses or 
certificates (after approval of a superior) immediately upon finding a 
violation or equipment failure that directly affects emission reduction 
benefits, pending a hearing when requested. In the case of immediate 
suspension, a hearing shall be held within fourteen calendar days of a 
written request by the station licensee or the inspector. Failure to 
hold a hearing within 14 days when requested shall cause the suspension 
to lapse. In the event that a State's constitution precludes such a 
temporary license suspension, the enforcement system shall be designed 
with adequate resources and mechanisms to hold a hearing to suspend or 
revoke the station or inspector license within three station business 
days of the finding.
    (2) The oversight agency shall have the authority to impose 
penalties against the licensed station or contractor, as well as the 
inspector, even if the licensee or contractor had no direct knowledge of 
the violation but was found to be careless in oversight of inspectors or 
has a history of violations. Contractors and licensees shall be held 
fully responsible for inspector performance in the course of duty.
    (c) Recordkeeping. The oversight agency shall maintain records of 
all warnings, civil fines, suspensions, revocations, and violations and 
shall compile statistics on violations and penalties on an annual basis.
    (d) SIP requirements. (1) The SIP shall include the penalty schedule 
and the legal authority for establishing and imposing penalties, civil 
fines, license suspension, and revocations.
    (2) In the case of State constitutional impediments to immediate 
suspension authority, the State Attorney General shall furnish an 
official opinion for the SIP explaining the constitutional impediment as 
well as relevant case law.
    (3) The SIP shall describe the administrative and judicial 
procedures and responsibilities relevant to the enforcement process, 
including which agencies, courts, and jurisdictions are involved; who 
will prosecute and adjudicate cases; and other aspects of the 
enforcement of the program requirements, the resources to be allocated 
to this function, and the source of those funds. In States without 
immediate suspension authority, the SIP shall demonstrate that 
sufficient resources, personnel, and systems are in place to meet the 
three day case management requirement for violations that directly 
affect emission reductions.
    (e) Alternative quality assurance procedures or frequencies that 
achieve equivalent or better results may be approved by the 
Administrator. Statistical process control shall be used whenever 
possible to demonstrate the efficacy of alternatives.
    (f) Areas that qualify for and choose to implement an OTR low 
enhanced I/M program, as established in Sec. 51.351(h), and that claim 
in their SIP less emission reduction credit than the basic performance 
standard for one or more pollutants, are not required to meet the 
oversight specifications of this section.

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 39037, July 25, 1996]



Sec. 51.365  Data collection.

    Accurate data collection is essential to the management, evaluation, 
and enforcement of an I/M program. The program shall gather test data on 
individual vehicles, as well as quality control data on test equipment 
(with the exception of test procedures for which either no testing 
equipment is required or those test procedures relying upon a vehicle's 
OBD system).
    (a) Test data. The goal of gathering test data is to unambiguously 
link specific test results to a specific vehicle, I/M program 
registrant, test site, and inspector, and to determine whether or not 
the correct testing parameters were observed for the specific vehicle in 
question. In turn, these data can be used to distinguish complying and 
noncomplying vehicles as a result of analyzing the data collected and 
comparing it to the registration database, to screen inspection stations 
and inspectors for investigation as to possible irregularities, and to 
help establish the overall effectiveness of the program. At a minimum, 
the program shall collect the following with respect to each test 
conducted:
    (1) Test record number;

[[Page 353]]

    (2) Inspection station and inspector numbers;
    (3) Test system number (where applicable);
    (4) Date of the test;
    (5) Emission test start time and the time final emission scores are 
determined;
    (6) Vehicle Identification Number;
    (7) License plate number;
    (8) Test certificate number;
    (9) Gross Vehicle Weight Rating (GVWR);
    (10) Vehicle model year, make, and type;
    (11) Number of cylinders or engine displacement;
    (12) Transmission type;
    (13) Odometer reading;
    (14) Category of test performed (i.e., initial test, first retest, 
or subsequent retest);
    (15) Fuel type of the vehicle (i.e., gas, diesel, or other fuel);
    (16) Type of vehicle preconditioning performed (if any);
    (17) Emission test sequence(s) used;
    (18) Hydrocarbon emission scores and standards for each applicable 
test mode;
    (19) Carbon monoxide emission scores and standards for each 
applicable test mode;
    (20) Carbon dioxide emission scores (CO + CO2) and 
standards for each applicable test mode;
    (21) Nitrogen oxides emission scores and standards for each 
applicable test mode;
    (22) Results (Pass/Fail/Not Applicable) of the applicable visual 
inspections for the catalytic converter, air system, gas cap, 
evaporative system, positive crankcase ventilation (PCV) valve, fuel 
inlet restrictor, and any other visual inspection for which emission 
reduction credit is claimed;
    (23) Results of the evaporative system pressure test(s) expressed as 
a pass or fail;
    (24) Results of the evaporative system purge test expressed as a 
pass or fail along with the total purge flow in liters achieved during 
the test (where applicable); and
    (25) Results of the on-board diagnostic check expressed as a pass or 
fail along with the diagnostic trouble codes revealed (where 
applicable).
    (b) Quality control data. At a minimum, the program shall gather and 
report the results of the quality control checks required under Sec. 
51.359 of this subpart, identifying each check by station number, system 
number, date, and start time. The data report shall also contain the 
concentration values of the calibration gases used to perform the gas 
characterization portion of the quality control checks (where 
applicable).

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996; 65 
FR 45534, July 24, 2000]



Sec. 51.366  Data analysis and reporting.

    Data analysis and reporting are required to allow for monitoring and 
evaluation of the program by program management and EPA, and shall 
provide information regarding the types of program activities performed 
and their final outcomes, including summary statistics and effectiveness 
evaluations of the enforcement mechanism, the quality assurance system, 
the quality control program, and the testing element. Initial submission 
of the following annual reports shall commence within 18 months of 
initial implementation of the program as required by Sec. 51.373 of 
this subpart. The biennial report shall commence within 30 months of 
initial implementation of the program as required by Sec. 51.373 of 
this subpart.
    (a) Test data report. The program shall submit to EPA by July of 
each year a report providing basic statistics on the testing program for 
January through December of the previous year, including:
    (1) The number of vehicles tested by model year and vehicle type;
    (2) By model year and vehicle type, the number and percentage of 
vehicles:
    (i) Failing initially, per test type;
    (ii) Failing the first retest per test type;
    (iii) Passing the first retest per test type;
    (iv) Initially failed vehicles passing the second or subsequent 
retest per test type;
    (v) Initially failed vehicles receiving a waiver; and
    (vi) Vehicles with no known final outcome (regardless of reason).

[[Page 354]]

    (vii)-(x) [Reserved]
    (xi) Passing the on-board diagnostic check;
    (xii) Failing the on-board diagnostic check;
    (xiii) Failing the on-board diagnostic check and passing the 
tailpipe test (if applicable);
    (xiv) Failing the on-board diagnostic check and failing the tailpipe 
test (if applicable);
    (xv) Passing the on-board diagnostic check and failing the I/M gas 
cap evaporative system test (if applicable);
    (xvi) Failing the on-board diagnostic check and passing the I/M gas 
cap evaporative system test (if applicable);
    (xvii) Passing both the on-board diagnostic check and I/M gas cap 
evaporative system test (if applicable);
    (xviii) Failing both the on-board diagnostic check and I/M gas cap 
evaporative system test (if applicable);
    (xix) MIL is commanded on and no codes are stored;
    (xx) MIL is not commanded on and codes are stored;
    (xxi) MIL is commanded on and codes are stored;
    (xxii) MIL is not commanded on and codes are not stored;
    (xxiii) Readiness status indicates that the evaluation is not 
complete for any module supported by on-board diagnostic systems;
    (3) The initial test volume by model year and test station;
    (4) The initial test failure rate by model year and test station; 
and
    (5) The average increase or decrease in tailpipe emission levels for 
HC, CO, and NOX (if applicable) after repairs by model year 
and vehicle type for vehicles receiving a mass emissions test.
    (b) Quality assurance report. The program shall submit to EPA by 
July of each year a report providing basic statistics on the quality 
assurance program for January through December of the previous year, 
including:
    (1) The number of inspection stations and lanes:
    (i) Operating throughout the year; and
    (ii) Operating for only part of the year;
    (2) The number of inspection stations and lanes operating throughout 
the year:
    (i) Receiving overt performance audits in the year;
    (ii) Not receiving overt performance audits in the year;
    (iii) Receiving covert performance audits in the year;
    (iv) Not receiving covert performance audits in the year; and
    (v) That have been shut down as a result of overt performance 
audits;
    (3) The number of covert audits:
    (i) Conducted with the vehicle set to fail per test type;
    (ii) Conducted with the vehicle set to fail any combination of two 
or more test types;
    (iii) Resulting in a false pass per test type;
    (iv) Resulting in a false pass for any combination of two or more 
test types;
    (v)-(viii) [Reserved]
    (4) The number of inspectors and stations:
    (i) That were suspended, fired, or otherwise prohibited from testing 
as a result of covert audits;
    (ii) That were suspended, fired, or otherwise prohibited from 
testing for other causes; and
    (iii) That received fines;
    (5) The number of inspectors licensed or certified to conduct 
testing;
    (6) The number of hearings:
    (i) Held to consider adverse actions against inspectors and 
stations; and
    (ii) Resulting in adverse actions against inspectors and stations;
    (7) The total amount collected in fines from inspectors and stations 
by type of violation;
    (8) The total number of covert vehicles available for undercover 
audits over the year; and
    (9) The number of covert auditors available for undercover audits.
    (c) Quality control report. The program shall submit to EPA by July 
of each year a report providing basic statistics on the quality control 
program for January through December of the previous year, including:
    (1) The number of emission testing sites and lanes in use in the 
program;
    (2) The number of equipment audits by station and lane;
    (3) The number and percentage of stations that have failed equipment 
audits; and

[[Page 355]]

    (4) Number and percentage of stations and lanes shut down as a 
result of equipment audits.
    (d) Enforcement report. (1) All varieties of enforcement programs 
shall, at a minimum, submit to EPA by July of each year a report 
providing basic statistics on the enforcement program for January 
through December of the previous year, including:
    (i) An estimate of the number of vehicles subject to the inspection 
program, including the results of an analysis of the registration data 
base;
    (ii) The percentage of motorist compliance based upon a comparison 
of the number of valid final tests with the number of subject vehicles;
    (iii) The total number of compliance documents issued to inspection 
stations;
    (iv) The number of missing compliance documents;
    (v) The number of time extensions and other exemptions granted to 
motorists; and
    (vi) The number of compliance surveys conducted, number of vehicles 
surveyed in each, and the compliance rates found.
    (2) Registration denial based enforcement programs shall provide the 
following additional information:
    (i) A report of the program's efforts and actions to prevent 
motorists from falsely registering vehicles out of the program area or 
falsely changing fuel type or weight class on the vehicle registration, 
and the results of special studies to investigate the frequency of such 
activity; and
    (ii) The number of registration file audits, number of registrations 
reviewed, and compliance rates found in such audits.
    (3) Computer-matching based enforcement programs shall provide the 
following additional information:
    (i) The number and percentage of subject vehicles that were tested 
by the initial deadline, and by other milestones in the cycle;
    (ii) A report on the program's efforts to detect and enforce against 
motorists falsely changing vehicle classifications to circumvent program 
requirements, and the frequency of this type of activity; and
    (iii) The number of enforcement system audits, and the error rate 
found during those audits.
    (4) Sticker-based enforcement systems shall provide the following 
additional information:
    (i) A report on the program's efforts to prevent, detect, and 
enforce against sticker theft and counterfeiting, and the frequency of 
this type of activity;
    (ii) A report on the program's efforts to detect and enforce against 
motorists falsely changing vehicle classifications to circumvent program 
requirements, and the frequency of this type of activity; and
    (iii) The number of parking lot sticker audits conducted, the number 
of vehicles surveyed in each, and the noncompliance rate found during 
those audits.
    (e) Additional reporting requirements. In addition to the annual 
reports in paragraphs (a) through (d) of this section, programs shall 
submit to EPA by July of every other year, biennial reports addressing:
    (1) Any changes made in program design, funding, personnel levels, 
procedures, regulations, and legal authority, with detailed discussion 
and evaluation of the impact on the program of all such changes; and
    (2) Any weaknesses or problems identified in the program within the 
two-year reporting period, what steps have already been taken to correct 
those problems, the results of those steps, and any future efforts 
planned.
    (f) SIP requirements. The SIP shall describe the types of data to be 
collected.

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996; 65 
FR 45534, July 24, 2000; 66 FR 18178, Apr. 5, 2001]



Sec. 51.367  Inspector training and licensing or certification.

    All inspectors shall receive formal training and be licensed or 
certified to perform inspections.
    (a) Training. (1) Inspector training shall impart knowledge of the 
following:
    (i) The air pollution problem, its causes and effects;
    (ii) The purpose, function, and goal of the inspection program;
    (iii) Inspection regulations and procedures;

[[Page 356]]

    (iv) Technical details of the test procedures and the rationale for 
their design;
    (v) Emission control device function, configuration, and inspection;
    (vi) Test equipment operation, calibration, and maintenance (with 
the exception of test procedures which either do not require the use of 
special equipment or which rely upon a vehicle's OBD system);
    (vii) Quality control procedures and their purpose;
    (viii) Public relations; and
    (ix) Safety and health issues related to the inspection process.
    (2) If inspector training is not administered by the program, the 
responsible State agency shall monitor and evaluate the training program 
delivery.
    (3) In order to complete the training requirement, a trainee shall 
pass (i.e., a minimum of 80% of correct responses or lower if an 
occupational analysis justifies it) a written test covering all aspects 
of the training. In addition, a hands-on test shall be administered in 
which the trainee demonstrates without assistance the ability to conduct 
a proper inspection and to follow other required procedures. Inability 
to properly conduct all test procedures shall constitute failure of the 
test. The program shall take appropriate steps to insure the security 
and integrity of the testing process.
    (b) Licensing and certification. (1) All inspectors shall be either 
licensed by the program (in the case of test-and-repair systems that do 
not use contracts with stations) or certified by an organization other 
than the employer (in test-only programs and test-and-repair programs 
that require station owners to enter into contracts with the State) in 
order to perform official inspections.
    (2) Completion of inspector training and passing required tests 
shall be a condition of licensing or certification.
    (3) Inspector licenses and certificates shall be valid for no more 
than 2 years, at which point refresher training and testing shall be 
required prior to renewal. Alternative approaches based on more 
comprehensive skill examination and determination of inspector 
competency may be used.
    (4) Licenses or certificates shall not be considered a legal right 
but rather a privilege bestowed by the program conditional upon 
adherence to program requirements.
    (c) SIP requirements. The SIP shall include a description of the 
training program, the written and hands-on tests, and the licensing or 
certification process.

[57 FR 52987, Nov. 5, 1992, as amended at 65 FR 45534, July 24, 2000]



Sec. 51.368  Public information and consumer protection.

    (a) Public awareness. The SIP shall include a plan for informing the 
public on an ongoing basis throughout the life of the I/M program of the 
air quality problem, the requirements of Federal and State law, the role 
of motor vehicles in the air quality problem, the need for and benefits 
of an inspection program, how to maintain a vehicle in a low-emission 
condition, how to find a qualified repair technician, and the 
requirements of the I/M program. Motorists that fail the I/M test in 
enhanced I/M areas shall be offered a list of repair facilities in the 
area and information on the results of repairs performed by repair 
facilities in the area, as described in Sec. 51.369(b)(1) of this 
subpart. Motorists that fail the I/M test shall also be provided with 
information concerning the possible cause(s) for failing the particular 
portions of the test that were failed.
    (b) Consumer protection. The oversight agency shall institute 
procedures and mechanisms to protect the public from fraud and abuse by 
inspectors, mechanics, and others involved in the I/M program. This 
shall include a challenge mechanism by which a vehicle owner can contest 
the results of an inspection. It shall include mechanisms for protecting 
whistle blowers and following up on complaints by the public or others 
involved in the process. It shall include a program to assist owners in 
obtaining warranty covered repairs for eligible vehicles that fail a 
test. The SIP shall include a detailed consumer protection plan.

[57 FR 52987, Nov. 5, 1992, as amended at 65 FR 45534, July 24, 2000]

[[Page 357]]



Sec. 51.369  Improving repair effectiveness.

    Effective repairs are the key to achieving program goals and the 
State shall take steps to ensure the capability exists in the repair 
industry to repair vehicles that fail I/M tests.
    (a) Technical assistance. The oversight agency shall provide the 
repair industry with information and assistance related to vehicle 
inspection diagnosis and repair.
    (1) The agency shall regularly inform repair facilities of changes 
in the inspection program, training course schedules, common problems 
being found with particular engine families, diagnostic tips and the 
like.
    (2) The agency shall provide a hot line service to assist repair 
technicians with specific repair problems, answer technical questions 
that arise in the repair process, and answer questions related to the 
legal requirements of State and Federal law with regard to emission 
control device tampering, engine switching, or similar issues.
    (b) Performance monitoring. (1) In enhanced I/M program areas, the 
oversight agency shall monitor the performance of individual motor 
vehicle repair facilities, and provide to the public at the time of 
initial failure, a summary of the performance of local repair facilities 
that have repaired vehicles for retest. Performance monitoring shall 
include statistics on the number of vehicles submitted for a retest 
after repair by the repair facility, the percentage passing on first 
retest, the percentage requiring more than one repair/retest trip before 
passing, and the percentage receiving a waiver. Programs may provide 
motorists with alternative statistics that convey similar information on 
the relative ability of repair facilities in providing effective and 
convenient repair, in light of the age and other characteristics of 
vehicles presented for repair at each facility.
    (2) Programs shall provide feedback, including statistical and 
qualitative information to individual repair facilities on a regular 
basis (at least annually) regarding their success in repairing failed 
vehicles.
    (3) A prerequisite for a retest shall be a completed repair form 
that indicates which repairs were performed, as well as any technician 
recommended repairs that were not performed, and identification of the 
facility that performed the repairs.
    (c) Repair technician training. The State shall assess the 
availability of adequate repair technician training in the I/M area and, 
if the types of training described in paragraphs (c)(1) through (4) of 
this section are not currently available, shall insure that training is 
made available to all interested individuals in the community either 
through private or public facilities. This may involve working with 
local community colleges or vocational schools to add curricula to 
existing programs or start new programs or it might involve attracting 
private training providers to offer classes in the area. The training 
available shall include:
    (1) Diagnosis and repair of malfunctions in computer controlled, 
close-loop vehicles;
    (2) The application of emission control theory and diagnostic data 
to the diagnosis and repair of failures on the transient emission test 
and the evaporative system functional checks (where applicable);
    (3) Utilization of diagnostic information on systematic or repeated 
failures observed in the transient emission test and the evaporative 
system functional checks (where applicable); and
    (4) General training on the various subsystems related to engine 
emission control.
    (d) SIP requirements. The SIP shall include a description of the 
technical assistance program to be implemented, a description of the 
procedures and criteria to be used in meeting the performance monitoring 
requirements of this section, and a description of the repair technician 
training resources available in the community.

[57 FR 52987, Nov. 5, 1992, as amended at 65 FR 45535, July 24, 2000]



Sec. 51.370  Compliance with recall notices.

    States shall establish methods to ensure that vehicles subject to 
enhanced I/M and that are included in either a

[[Page 358]]

``Voluntary Emissions Recall'' as defined at 40 CFR 85.1902(d), or in a 
remedial plan determination made pursuant to section 207(c) of the Act, 
receive the required repairs. States shall require that owners of 
recalled vehicles have the necessary recall repairs completed, either in 
order to complete an annual or biennial inspection process or to obtain 
vehicle registration renewal. All recalls for which owner notification 
occurs after January 1, 1995 shall be included in the enhanced I/M 
recall requirement.
    (a) General requirements. (1) The State shall have an electronic 
means to identify recalled vehicles based on lists of VINs with 
unresolved recalls made available by EPA, the vehicle manufacturers, or 
a third party supplier approved by the Administrator. The State shall 
update its list of unresolved recalls on a quarterly basis at a minimum.
    (2) The State shall require owners or lessees of vehicles with 
unresolved recalls to show proof of compliance with recall notices in 
order to complete either the inspection or registration cycle.
    (3) Compliance shall be required on the next registration or 
inspection date, allowing a reasonable period to comply, after 
notification of recall was received by the State.
    (b) Enforcement. (1) A vehicle shall either fail inspection or be 
denied vehicle registration if the required recall repairs have not been 
completed.
    (2) In the case of vehicles obtaining recall repairs but remaining 
on the updated list provided in paragraph (a)(1) of this section, the 
State shall have a means of verifying completion of the required 
repairs; electronic records or paper receipts provided by the authorized 
repair facility shall be required. The vehicle inspection or 
registration record shall be modified to include (or be supplemented 
with other VIN-linked records which include) the recall campaign 
number(s) and the date(s) repairs were performed. Documentation 
verifying required repairs shall include the following:
    (i) The VIN, make, and model year of the vehicle; and
    (ii) The recall campaign number and the date repairs were completed.
    (c) Reporting requirements. The State shall submit to EPA, by July 
of each year for the previous calendar year, an annual report providing 
the following information:
    (1) The number of vehicles in the I/M area initially listed as 
having unresolved recalls, segregated by recall campaign number;
    (2) The number of recalled vehicles brought into compliance by 
owners;
    (3) The number of listed vehicles with unresolved recalls that, as 
of the end of the calendar year, were not yet due for inspection or 
registration;
    (4) The number of recalled vehicles still in non-compliance that 
have either failed inspection or been denied registration on the basis 
of non-compliance with recall; and
    (5) The number of recalled vehicles that are otherwise not in 
compliance.
    (d) SIP submittals. The SIP shall describe the procedures used to 
incorporate the vehicle lists provided in paragraph (a)(1) of this 
section into the inspection or registration database, the quality 
control methods used to insure that recall repairs are properly 
documented and tracked, and the method (inspection failure or 
registration denial) used to enforce the recall requirements.



Sec. 51.371  On-road testing.

    On-road testing is defined as testing of vehicles for conditions 
impacting the emission of HC, CO, NOX and/or CO2 emissions on 
any road or roadside in the nonattainment area or the I/M program area. 
On-road testing is required in enhanced I/M areas and is an option for 
basic I/M areas.
    (a) General requirements. (1) On-road testing is to be part of the 
emission testing system, but is to be a complement to testing otherwise 
required.
    (2) On-road testing is not required in every season or on every 
vehicle but shall evaluate the emission performance of 0.5% of the 
subject fleet statewide or 20,000 vehicles, whichever is less, per 
inspection cycle.
    (3) The on-road testing program shall provide information about the 
performance of in-use vehicles, by measuring on-road emissions through 
the use of remote sensing devices or by assessing vehicle emission 
performance through

[[Page 359]]

roadside pullovers including tailpipe or evaporative emission testing or 
a check of the onboard diagnostic (OBD) system for vehicles so equipped. 
The program shall collect, analyze and report on-road testing data.
    (4) Owners of vehicles that have previously been through the normal 
periodic inspection and passed the final retest and found to be high 
emitters shall be notified that the vehicles are required to pass an 
out-of-cycle follow-up inspection; notification may be by mailing in the 
case of remote sensing on-road testing or through immediate notification 
if roadside pullovers are used.
    (b) SIP requirements. (1) The SIP shall include a detailed 
description of the on-road testing program, including the types of 
testing, test limits and criteria, the number of vehicles (the 
percentage of the fleet) to be tested, the number of employees to be 
dedicated to the on-road testing effort, the methods for collecting, 
analyzing, utilizing, and reporting the results of on-road testing and, 
the portion of the program budget to be dedicated to on-road testing.
    (2) The SIP shall include the legal authority necessary to implement 
the on-road testing program, including the authority to enforce off-
cycle inspection and repair requirements (where applicable).
    (3) Emission reduction credit for on-road testing programs shall be 
granted for a program designed to obtain measurable emission reductions 
over and above those already predicted to be achieved by other aspects 
of the I/M program. Emission reduction credit will only be granted to 
those programs which require out-of-cycle repairs for confirmed high-
emitting vehicles identified under the on-road testing program. The SIP 
shall include technical support for the claimed additional emission 
reductions.

[57 FR 52987, Nov. 5, 1992, as amended at 65 FR 45535, July 24, 2000]



Sec. 51.372  State Implementation Plan submissions.

    (a) SIP submittals. The SIP shall address each of the elements 
covered in this subpart, including, but not limited to:
    (1) A schedule of implementation of the program including interim 
milestones leading to mandatory testing. The milestones shall include, 
at a minimum:
    (i) Passage of enabling statutory or other legal authority;
    (ii) Proposal of draft regulations and promulgation of final 
regulations;
    (iii) Issuance of final specifications and procedures;
    (iv) Issuance of final Request for Proposals (if applicable);
    (v) Licensing or certifications of stations and inspectors;
    (vi) The date mandatory testing will begin for each model year to be 
covered by the program;
    (vii) The date full-stringency cutpoints will take effect;
    (viii) All other relevant dates;
    (2) An analysis of emission level targets for the program using the 
most current EPA mobile source emission model or an alternative approved 
by the Administrator showing that the program meets the performance 
standard described in Sec. 51.351 or Sec. 51.352 of this subpart, as 
applicable;
    (3) A description of the geographic coverage of the program, 
including ZIP codes if the program is not county-wide;
    (4) A detailed discussion of each of the required design elements, 
including provisions for Federal facility compliance;
    (5) Legal authority requiring or allowing implementation of the I/M 
program and providing either broad or specific authority to perform all 
required elements of the program;
    (6) Legal authority for I/M program operation until such time as it 
is no longer necessary (i.e., until a Section 175 maintenance plan 
without an I/M program is approved by EPA);
    (7) Implementing regulations, interagency agreements, and memoranda 
of understanding; and
    (8) Evidence of adequate funding and resources to implement all 
aspects of the program.
    (b) Submittal schedule. The SIP shall be submitted to EPA according 
to the following schedule--
    (1) [Reserved]
    (2) A SIP revision required as a result of a change in an area's 
designation or

[[Page 360]]

classification under a NAAQS for ozone, including all necessary legal 
authority and the items specified in paragraphs (a)(1) through (8) of 
this section, shall be submitted no later than the deadline for 
submitting the area's attainment SIP for the NAAQS in question.
    (3) [Reserved]
    (c) Redesignation requests. Any nonattainment area that EPA 
determines would otherwise qualify for redesignation from nonattainment 
to attainment shall receive full approval of a State Implementation Plan 
(SIP) submittal under Sections 182(a)(2)(B) or 182(b)(4) if the 
submittal contains the following elements:
    (1) Legal authority to implement a basic I/M program (or enhanced if 
the State chooses to opt up) as required by this subpart. The 
legislative authority for an I/M program shall allow the adoption of 
implementing regulations without requiring further legislation.
    (2) A request to place the I/M plan (if no I/M program is currently 
in place or if an I/M program has been terminated,) or the I/M upgrade 
(if the existing I/M program is to continue without being upgraded) into 
the contingency measures portion of the maintenance plan upon 
redesignation.
    (3) A contingency measure consisting of a commitment by the Governor 
or the Governor's designee to adopt or consider adopting regulations to 
implement an I/M program to correct a violation of the ozone or CO 
standard or other air quality problem, in accordance with the provisions 
of the maintenance plan.
    (4) A contingency commitment that includes an enforceable schedule 
for adoption and implementation of the I/M program, and appropriate 
milestones. The schedule shall include the date for submission of a SIP 
meeting all of the requirements of this subpart. Schedule milestones 
shall be listed in months from the date EPA notifies the State that it 
is in violation of the ozone or CO standard or any earlier date 
specified in the State plan. Unless the State, in accordance with the 
provisions of the maintenance plan, chooses not to implement I/M, it 
must submit a SIP revision containing an I/M program no more than 18 
months after notification by EPA.
    (d) Basic areas continuing operation of I/M programs as part of 
their maintenance plan without implemented upgrades shall be assumed to 
be 80% as effective as an implemented, upgraded version of the same I/M 
program design, unless a State can demonstrate using operating 
information that the I/M program is more effective than the 80% level.
    (e) SIP submittals to correct violations. SIP submissions required 
pursuant to a violation of the ambient ozone or CO standard (as 
discussed in paragraph (c) of this section) shall address all of the 
requirements of this subpart. The SIP shall demonstrate that performance 
standards in either Sec. 51.351 or Sec. 51.352 shall be met using an 
evaluation date (rounded to the nearest January for carbon monoxide and 
July for hydrocarbons) seven years after the date EPA notifies the State 
that it is in violation of the ozone or CO standard or any earlier date 
specified in the State plan. Emission standards for vehicles subject to 
an IM240 test may be phased in during the program but full standards 
must be in effect for at least one complete test cycle before the end of 
the 5-year period. All other requirements shall take effect within 24 
months of the date EPA notifies the State that it is in violation of the 
ozone or CO standard or any earlier date specified in the State plan. 
The phase-in allowances of Sec. 51.373(c) of this subpart shall not 
apply.

[57 FR 52987, Nov. 5, 1992, as amended at 60 FR 1738, Jan. 5, 1995; 60 
FR 48036, Sept. 18, 1995; 61 FR 40946, Aug. 6, 1996; 61 FR 44119, Aug. 
27, 1996; 71 FR 17711, Apr. 7, 2006; 80 FR 12318, Mar. 6, 2015]



Sec. 51.373  Implementation deadlines.

    I/M programs shall be implemented as expeditiously as practicable.
    (a) Decentralized basic programs shall be fully implemented by 
January 1, 1994, and centralized basic programs shall be fully 
implemented by July 1, 1994. More implementation time may be approved by 
the Administrator if an enhanced I/M program is implemented.

[[Page 361]]

    (b) For areas newly required to implement basic I/M as a result of 
designation under the 8-hour ozone standard, the required program shall 
be fully implemented no later than 4 years after the effective date of 
designation and classification under the 8-hour ozone standard.
    (c) All requirements related to enhanced I/M programs shall be 
implemented by January 1, 1995, with the following exceptions.
    (1) Areas switching from an existing test-and-repair network to a 
test-only network may phase in the change between January of 1995 and 
January of 1996. Starting in January of 1995 at least 30% of the subject 
vehicles shall participate in the test-only system (in States with 
multiple I/M areas, implementation is not required in every area by 
January 1995 as long as statewide, 30% of the subject vehicles are 
involved in testing) and shall be subject to the new test procedures 
(including the evaporative system checks, visual inspections, and 
tailpipe emission tests). By January 1, 1996, all applicable vehicle 
model years and types shall be included in the test-only system. During 
the phase-in period, all requirements of this subpart shall be applied 
to the test-only portion of the program; existing requirements may 
continue to apply for the test-and-repair portion of the program until 
it is phased out by January 1, 1996.
    (2) Areas starting new test-only programs and those with existing 
test-only programs may also phase in the new test procedures between 
January 1, 1995 and January 1, 1996. Other program requirements shall be 
fully implemented by January 1, 1995.
    (d) For areas newly required to implement enhanced I/M as a result 
of designation under the 8-hour ozone standard, the required program 
shall be fully implemented no later than 4 years after the effective 
date of designation and classification under the 8-hour ozone standard.
    (e) [Reserved]
    (f) Areas that choose to implement an enhanced I/M program only 
meeting the requirements of Sec. 51.351(h) shall fully implement the 
program no later than July 1, 1999. The availability and use of this 
late start date does not relieve the area of the obligation to meet the 
requirements of Sec. 51.351(h)(11) by the end of 1999.
    (g) On-Board Diagnostic checks shall be implemented in all basic, 
low enhanced and high enhanced areas as part of the I/M program by 
January 1, 2002. Alternatively, states may elect to phase-in OBD-I/M 
testing for one test cycle by using the OBD-I/M check to screen clean 
vehicles from tailpipe testing and require repair and retest for only 
those vehicles which proceed to fail the tailpipe test. An additional 
alternative is also available to states with regard to the deadline for 
mandatory testing, repair, and retesting of vehicles based upon the OBD-
I/M check. Under this third option, if a state can show good cause (and 
the Administrator takes notice-and-comment action to approve this good 
cause showing), up to an additional 12 months' extension may be granted, 
establishing an alternative start date for such states of no later than 
January 1, 2003. States choosing to make this showing will also have 
available to them the phase-in approach described in this section, with 
the one-cycle time limit to begin coincident with the alternative start 
date established by Administrator approval of the showing, but no later 
than January 1, 2003. The showing of good cause (and its approval or 
disapproval) will be addressed on a case-by-case basis.
    (h) For areas newly required to implement either a basic or enhanced 
I/M program as a result of being designated and classified under the 8-
hour ozone standard, such programs shall begin OBD testing on subject 
OBD-equipped vehicles coincident with program start-up.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993; 61 
FR 39037, July 25, 1996; 61 FR 40946, Aug. 6, 1996; 63 FR 24433, May 4, 
1998; 66 FR 18178, Apr. 5, 2001; 71 FR 17711, Apr. 7, 2006]



 Sec. Appendix A to Subpart S of Part 51--Calibrations, Adjustments and 
                             Quality Control

                     (I) Steady-State Test Equipment

    States may opt to use transient emission test equipment for steady-
state tests and follow the quality control requirements in

[[Page 362]]

paragraph (II) of this appendix instead of the following requirements.
    (a) Equipment shall be calibrated in accordance with the 
manufacturers' instructions.
    (b) Prior to each test--(1) Hydrocarbon hang-up check. Immediately 
prior to each test the analyzer shall automatically perform a 
hydrocarbon hang-up check. If the HC reading, when the probe is sampling 
ambient air, exceeds 20 ppm, the system shall be purged with clean air 
or zero gas. The analyzer shall be inhibited from continuing the test 
until HC levels drop below 20 ppm.
    (2) Automatic zero and span. The analyzer shall conduct an automatic 
zero and span check prior to each test. The span check shall include the 
HC, CO, and CO2 channels, and the NO and O2 channels, if 
present. If zero and/or span drift cause the signal levels to move 
beyond the adjustment range of the analyzer, it shall lock out from 
testing.
    (3) Low flow. The system shall lock out from testing if sample flow 
is below the acceptable level as defined in paragraph (I)(b)(6) of 
appendix D to this subpart.
    (c) Leak check. A system leak check shall be performed within 
twenty-four hours before the test in low volume stations (those 
performing less than the 4,000 inspections per year) and within four 
hours in high-volume stations (4,000 or more inspections per year) and 
may be performed in conjunction with the gas calibration described in 
paragraph (I)(d)(1) of this appendix. If a leak check is not performed 
within the preceding twenty-four hours in low volume stations and within 
four hours in high-volume stations or if the analyzer fails the leak 
check, the analyzer shall lock out from testing. The leak check shall be 
a procedure demonstrated to effectively check the sample hose and probe 
for leaks and shall be performed in accordance with good engineering 
practices. An error of more than 2% of the reading 
using low range span gas shall cause the analyzer to lock out from 
testing and shall require repair of leaks.
    (d) Gas calibration. (1) On each operating day in high-volume 
stations, analyzers shall automatically require and successfully pass a 
two-point gas calibration for HC, CO, and CO2 and shall continually 
compensate for changes in barometric pressure. Calibration shall be 
checked within four hours before the test and the analyzer adjusted if 
the reading is more than 2% different from the span gas value. In low-
volume stations, analyzers shall undergo a two-point calibration within 
seventy-two hours before each test, unless changes in barometric 
pressure are compensated for automatically and statistical process 
control demonstrates equal or better quality control using different 
frequencies. Gas calibration shall be accomplished by introducing span 
gas that meets the requirements of paragraph (I)(d)(3) of this appendix 
into the analyzer through the calibration port. If the analyzer reads 
the span gas within the allowable tolerance range (i.e., the square root 
of sum of the squares of the span gas tolerance described in paragraph 
(I)(d)(3) of this appendix and the calibration tolerance, which shall be 
equal to 2%), no adjustment of the analyzer is necessary. The gas 
calibration procedure shall correct readings that exceed the allowable 
tolerance range to the center of the allowable tolerance range. The 
pressure in the sample cell shall be the same with the calibration gas 
flowing during calibration as with the sample gas flowing during 
sampling. If the system is not calibrated, or the system fails the 
calibration check, the analyzer shall lock out from testing.
    (2) Span points. A two point gas calibration procedure shall be 
followed. The span shall be accomplished at one of the following pairs 
of span points:

(A) 300--ppm propane (HC)
1.0--% carbon monoxide (CO)
6.0--% carbon dioxide (CO2)
1000--ppm nitric oxide (if equipped with NO)
1200--ppm propane (HC)
4.0--% carbon monoxide (CO)
12.0--% carbon dioxide (CO2)
3000--ppm nitric oxide (if equipped with NO)
(B) --ppm propane
0.0--% carbon monoxide
0.0--% carbon dioxide
0--ppm nitric oxide (if equipped with NO)
600--ppm propane (HC)
1.6--% carbon monoxide (CO)
11.0--% carbon dioxide (CO2)
1200--ppm nitric oxide (if equipped with NO)

    (3) Span gases. The span gases used for the gas calibration shall be 
traceable to National Institute of Standards and Technology (NIST) 
standards 2%, and shall be within two percent of 
the span points specified in paragraph (d)(2) of this appendix. Zero 
gases shall conform to the specifications given in Sec. 86.114-79(a)(5) 
of this chapter.
    (e) Dynamometer checks--(1) Monthly check. Within one month 
preceding each loaded test, the accuracy of the roll speed indicator 
shall be verified and the dynamometer shall be checked for proper power 
absorber settings.
    (2) Semi-annual check. Within six months preceding each loaded test, 
the road-load response of the variable-curve dynamometer or the 
frictional power absorption of the dynamometer shall be checked by a 
coast down procedure similar to that described in Sec. 86.118-78 of 
this chapter. The check shall be done at 30 mph, and a power absorption 
load setting to generate a total horsepower (hp) of 4.1 hp. The actual 
coast down time from 45 mph to 15 mph shall be within 1 second of the time calculated by the following 
equation:

[[Page 363]]

[GRAPHIC] [TIFF OMITTED] TC08NO91.014

where W is the total inertia weight as represented by the weight of the 
rollers (excluding free rollers), and any inertia flywheels used, 
measured in pounds. If the coast down time is not within the specified 
tolerance the dynamometer shall be taken out of service and corrective 
action shall be taken.
    (f) Other checks. In addition to the above periodic checks, these 
shall also be used to verify system performance under the following 
special circumstances.
    (1) Gas Calibration. (A) Each time the analyzer electronic or 
optical systems are repaired or replaced, a gas calibration shall be 
performed prior to returning the unit to service.
    (B) In high-volume stations, monthly multi-point calibrations shall 
be performed. Low-volume stations shall perform multi-point calibrations 
every six months. The calibration curve shall be checked at 20%, 40%, 
60%, and 80% of full scale and adjusted or repaired if the 
specifications in appendix D(I)(b)(1) to this subpart are not met.
    (2) Leak checks. Each time the sample line integrity is broken, a 
leak check shall be performed prior to testing.

                      (II) Transient Test Equipment

    (a) Dynamometer. Once per week, the calibration of each dynamometer 
and each fly wheel shall be checked by a dynamometer coast-down 
procedure comparable to that in Sec. 86.118-78 of this chapter between 
the speeds of 55 to 45 mph, and between 30 to 20 mph. All rotating 
dynamometer components shall be included in the coast-down check for the 
inertia weight selected. For dynamometers with uncoupled rolls, the 
uncoupled rollers may undergo a separate coast-down check. If a vehicle 
is used to motor the dynamometer to the beginning coast-down speed, the 
vehicle shall be lifted off the dynamometer rolls before the coast-down 
test begins. If the difference between the measured coast-down time and 
the theoretical coast-down time is greater than + 1 second, the system 
shall lock out, until corrective action brings the dynamometer into 
calibration.
    (b) Constant volume sampler. (1) The constant volume sampler (CVS) 
flow calibration shall be checked daily by a procedure that identifies 
deviations in flow from the true value. Deviations greater than 4% shall be corrected.
    (2) The sample probe shall be cleaned and checked at least once per 
month. The main CVS venturi shall be cleaned and checked at least once 
per year.
    (3) Verification that flow through the sample probe is adequate for 
the design shall be done daily. Deviations greater than the design 
tolerances shall be corrected.
    (c) Analyzer system--(1) Calibration checks. (A) Upon initial 
operation, calibration curves shall be generated for each analyzer. The 
calibration curve shall consider the entire range of the analyzer as one 
curve. At least 6 calibration points plus zero shall be used in the 
lower portion of the range corresponding to an average concentration of 
approximately 2 gpm for HC, 30 gpm for CO, 3 gpm for NOX, and 
400 gpm for CO2. For the case where a low and a high range 
analyzer is used, the high range analyzer shall use at least 6 
calibration points plus zero in the lower portion of the high range 
scale corresponding to approximately 100% of the full-scale value of the 
low range analyzer. For all analyzers, at least 6 calibration points 
shall also be used to define the calibration curve in the region above 
the 6 lower calibration points. Gas dividers may be used to obtain the 
intermediate points for the general range classifications specified. The 
calibration curves generated shall be a polynomial of no greater order 
than 4th order, and shall fit the date within 0.5% at each calibration 
point.
    (B) For all calibration curves, curve checks, span adjustments, and 
span checks, the zero gas shall be considered a down-scale reference 
gas, and the analyzer zero shall be set at the trace concentration value 
of the specific zero gas used.
    (2) The basic curve shall be checked monthly by the same procedure 
used to generate the curve, and to the same tolerances.
    (3) On a daily basis prior to vehicle testing--
    (A) The curve for each analyzer shall be checked by adjusting the 
analyzer to correctly read a zero gas and an up-scale span gas, and then 
by correctly reading a mid-scale span gas within 2% of point. If the 
analyzer does not read the mid-scale span point within 2% of point, the 
system shall lock out. The up-scale span gas concentration for each 
analyzer shall correspond to approximately 80 percent of full scale, and 
the mid-point concentration shall correspond to approximately 15 percent 
of full scale; and
    (B) After the up-scale span check, each analyzer in a given facility 
shall analyze a sample of a random concentration corresponding to 
approximately 0.5 to 3 times the cut point (in gpm) for the constituent. 
The value of the random sample may be determined by a gas blender. The 
deviation in analysis from the sample concentration for each analyzer 
shall be recorded and compared to the historical mean and standard 
deviation for the analyzers at the facility and at all facilities. Any 
reading exceeding 3 sigma shall cause the analyzer to lock out.
    (4) Flame ionization detector check. Upon initial operation, and 
after maintenance to the detector, each Flame Ionization Detector

[[Page 364]]

(FID) shall be checked, and adjusted if necessary, for proper peaking 
and characterization. Procedures described in SAE Paper No. 770141 are 
recommended for this purpose. A copy of this paper may be obtained from 
the Society of Automotive Engineers, Inc. (SAE), 400 Commonwealth Drive, 
Warrendale, Pennsylvania, 15096-0001. Additionally, every month the 
response of each FID to a methane concentration of approximately 50 ppm 
CH4 shall be checked. If the response is outside of the range 
of 1.10 to 1.20, corrective action shall be taken to bring the FID 
response within this range. The response shall be computed by the 
following formula:
[GRAPHIC] [TIFF OMITTED] TC08NO91.015

    (5) Spanning frequency. The zero and up-scale span point shall be 
checked, and adjusted if necessary, at 2 hour intervals following the 
daily mid-scale curve check. If the zero or the up-scale span point 
drifts by more than 2% for the previous check (except for the first 
check of the day), the system shall lock out, and corrective action 
shall be taken to bring the system into compliance.
    (6) Spanning limit checks. The tolerance on the adjustment of the 
up-scale span point is 0.4% of point. A software algorithm to perform 
the span adjustment and subsequent calibration curve adjustment shall be 
used. However, software up-scale span adjustments greater than 10% shall cause the system to lock out, requiring system 
maintenance.
    (7) Integrator checks. Upon initial operation, and every three 
months thereafter, emissions from a randomly selected vehicle with 
official test value greater than 60% of the standard (determined 
retrospectively) shall be simultaneously sampled by the normal 
integration method and by the bag method in each lane. The data from 
each method shall be put into a historical data base for determining 
normal and deviant performance for each test lane, facility, and all 
facilities combined. Specific deviations exceeding 5% shall require corrective action.
    (8) Interference. CO and CO2 analyzers shall be checked 
prior to initial service, and on a yearly basis thereafter, for water 
interference. The specifications and procedures used shall generally 
comply with either Sec. 86.122-78 or Sec. 86.321-79 of this chapter.
    (9) NOX converter check. The converter efficiency of the 
NO2 to NO converter shall be checked on a weekly basis. The 
check shall generally conform to Sec. 86.123-78 of this chapter, or EPA 
MVEL Form 305-01. Equivalent methods may be approved by the 
Administrator.
    (10) NO/NOX flow balance. The flow balance between the NO 
and NOX test modes shall be checked weekly. The check may be 
combined with the NOX convertor check as illustrated in EPA 
MVEL Form 305-01.
    (11) Additional checks. Additional checks shall be performed on the 
HC, CO, CO2, and NOX analyzers according to best 
engineering practices for the measurement technology used to ensure that 
measurements meet specified accuracy requirements.
    (12) System artifacts (hang-up). Prior to each test a comparison 
shall be made between the background HC reading, the HC reading measured 
through the sample probe (if different), and the zero gas. Deviations 
from the zero gas greater than 10 parts per million carbon (ppmC) shall 
cause the analyzer to lock out.
    (13) Ambient background. The average of the pre-test and post-test 
ambient background levels shall be compared to the permissible levels of 
10 ppmC HC, 20 ppm CO, and 1 ppm NOX. If the permissible 
levels are exceeded, the test shall be voided and corrective action 
taken to lower the ambient background concentrations.
    (14) Analytical gases. Zero gases shall meet the requirements of 
Sec. 86.114-79(a)(5) of this chapter. NOX calibration gas 
shall be a single blend using nitrogen as the diluent. Calibration gas 
for the flame ionization detector shall be a single blend of propane 
with a diluent of air. Calibration gases for CO and CO2 shall 
be single blends using nitrogen or air as a diluent. Multiple blends of 
HC, CO, and CO2 in air may be used if shown to be stable and 
accurate.

                       (III) Purge Analysis System

    On a daily basis each purge flow meter shall be checked with a 
simulated purge flow against a reference flow measuring device with 
performance specifications equal to or better than those specified for 
the purge meter. The check shall include a mid-scale rate check, and a 
total flow check between 10 and 20 liters. Deviations greater than 
5% shall be corrected. On a monthly basis, the 
calibration of purge meters shall be checked for proper rate and total 
flow with three equally spaced points across the flow rate and the 
totalized flow range. Deviations exceeding the specified accuracy shall 
be corrected. The dynamometer quality assurance checks required under 
paragraph (II) of this

[[Page 365]]

appendix shall also apply to the dynamometer used for purge tests.

            (IV) Evaporative System Integrity Test Equipment

    (a) On a weekly basis pressure measurement devices shall be checked 
against a reference device with performance specifications equal to or 
better than those specified for the measurement device. Deviations 
exceeding the performance specifications shall be corrected. Flow 
measurement devices, if any, shall be checked according to paragraph III 
of this appendix.
    (b) Systems that monitor evaporative system leaks shall be checked 
for integrity on a daily basis by sealing and pressurizing.

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993]



        Sec. Appendix B to Subpart S of Part 51--Test Procedures

                              (I) Idle test

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a minimum rate of two times per second. The measured value 
for pass/fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart, and the measured 
value for HC and CO as described in paragraph (I)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
measured values for HC and CO are below or equal to the applicable short 
test standards. A vehicle shall fail the test mode if the values for 
either HC or CO, or both, in all simultaneous pairs of values are above 
the applicable standards.
    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) This test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a first-
chance test and a second-chance test as follows:
    (i) The first-chance test, as described under paragraph (c) of this 
section, shall consist of an idle mode.
    (ii) The second-chance test as described under paragraph (I)(d) of 
this appendix shall be performed only if the vehicle fails the first-
chance test.
    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The vehicle shall be tested in as-received condition with the 
transmission in neutral or park and all accessories turned off. The 
engine shall be at normal operating temperature (as indicated by a 
temperature gauge, temperature lamp, touch test on the radiator hose, or 
other visual observation for overheating).
    (ii) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle in accordance with the analyzer manufacturer's 
instructions. For 1996 and newer model year vehicles the OBD data link 
connector will be used to monitor RPM. In the event that an OBD data 
link connector is not available or that an RPM signal is not available 
over the data link connector, a tachometer shall be used instead.
    (iii) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (iv) The measured concentration of CO plus CO2 shall be 
greater than or equal to six percent.
    (c) First-chance test. The test timer shall start (tt = 0) when the 
conditions specified in paragraph (I)(b)(2) of this appendix are met. 
The first-chance test shall have an overall maximum test time of 145 
seconds (tt = 145). The first-chance test shall consist of an idle mode 
only.
    (1) The mode timer shall start (mt = 0) when the vehicle engine 
speed is between 350 and 1100 rpm. If engine speed exceeds 1100 rpm or 
falls below 350 rpm, the mode timer shall reset zero and resume timing. 
The minimum mode length shall be determined as described under paragraph 
(I)(c)(2) of this appendix. The maximum mode length shall be 90 seconds 
elapsed time (mt = 90).
    (2) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (i) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (ii) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt = 30), if 
prior to that time the criteria of paragraph (I)(c)(2)(i) of this 
appendix are not satisfied and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(I)(a)(2) of this appendix.

[[Page 366]]

    (iii) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt = 30) and 90 seconds (mt = 90), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (I)(a)(2) of this appendix.
    (iv) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (I)(c)(2)(i), (ii) 
and (iii) of this appendix is satisfied by an elapsed time of 90 seconds 
(mt = 90). Alternatively, the vehicle may be failed if the provisions of 
paragraphs (I)(c)(2)(i) and (ii) of this appendix are not met within an 
elapsed time of 30 seconds.
    (v) Optional. The vehicle may fail the first-chance test and the 
second-chance test shall be omitted if no exhaust gas concentration 
lower than 1800 ppm HC is found by an elapsed time of 30 seconds (mt = 
30).
    (d) Second-chance test. If the vehicle fails the first-chance test, 
the test timer shall reset to zero (tt = 0) and a second-chance test 
shall be performed. The second-chance test shall have an overall maximum 
test time of 425 seconds (tt = 425). The test shall consist of a 
preconditioning mode followed immediately by an idle mode.
    (1) Preconditioning mode. The mode timer shall start (mt = 0) when 
the engine speed is between 2200 and 2800 rpm. The mode shall continue 
for an elapsed time of 180 seconds (mt = 180). If engine speed falls 
below 2200 rpm or exceeds 2800 rmp for more than five seconds in any one 
excursion, or 15 seconds over all excursions, the mode timer shall reset 
to zero and resume timing.
    (2) Idle mode--(i) Ford Motor Company and Honda vehicles. The 
engines of 1981-1987 Ford Motor Company vehicles and 1984-1985 Honda 
Preludes shall be shut off for not more than 10 seconds and restarted. 
This procedure may also be used for 1988-1989 Ford Motor Company 
vehicles but should not be used for other vehicles. The probe may be 
removed from the tailpipe or the sample pump turned off if necessary to 
reduce analyzer fouling during the restart procedure.
    (ii) The mode timer shall start (mt = 0) when the vehicle engine 
speed is between 350 and 1100 rpm. If engine speed exceeds 1100 rpm or 
falls below 350 rpm, the mode timer shall reset to zero and resume 
timing. The minimum idle mode length shall be determined as described in 
paragraph (I)(d)(2)(iii) of this appendix. The maximum idle mode length 
shall be 90 seconds elapsed time (mt = 90).
    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the idle mode shall be terminated as follows:
    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt = 30), if 
prior to that time the criteria of paragraph (I)(d)(2)(iii)(A) of this 
appendix are not satisfied and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(I)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt = 30) and 90 seconds (mt = 90), measured values are less 
than or equal to the applicable short test standards described in 
paragraph (I)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (I)(d)(2)(iii)(A), 
(d)(2)(iii)(B), and (d)(2)(iii)(C) of this appendix are satisfied by an 
elapsed time of 90 seconds (mt = 90).

                        (II) Two Speed Idle Test

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a rate of two times per second. The measured value for pass/
fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart, and the measured 
value for HC and CO as described in paragraph (II)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
values for HC and CO are below or equal to the applicable short test 
standards. A vehicle shall fail the test mode if the values for either 
HC or CO, or both, in all simultaneous pairs of values are above the 
applicable standards.
    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) The test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a first-
chance test and a second-chance test as follows:

[[Page 367]]

    (i) The first-chance test, as described under paragraph (II)(c) of 
this appendix, shall consist of an idle mode followed by a high-speed 
mode.
    (ii) The second-chance high-speed mode, as described under paragraph 
(II)(c) of this appendix, shall immediately follow the first-chance 
high-speed mode. It shall be performed only if the vehicle fails the 
first-chance test. The second-chance idle mode, as described under 
paragraph (II)(d) of this appendix, shall follow the second-chance high-
speed mode and be performed only if the vehicle fails the idle mode of 
the first-chance test.
    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The vehicle shall be tested in as-received condition with the 
transmission in neutral or park and all accessories turned off. The 
engine shall be at normal operating temperature (as indicated by a 
temperature gauge, temperature lamp, touch test on the radiator hose, or 
other visual observation for overheating).
    (ii) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle in accordance with the analyzer manufacturer's 
instructions. For 1996 and newer model year vehicles the OBD data link 
connector will be used to monitor RPM. In the event that an OBD data 
link connector is not available or that an RPM signal is not available 
over the data link connector, a tachometer shall be used instead.
    (iii) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (iv) The measured concentration of CO plus CO2 shall be 
greater than or equal to six percent.
    (c) First-chance test and second-chance high-speed mode. The test 
timer shall start (tt = 0) when the conditions specified in paragraph 
(b)(2) of this section are met. The first-chance test and second-chance 
high-speed mode shall have an overall maximum test time of 425 seconds 
(tt = 425). The first-chance test shall consist of an idle mode followed 
immediately by a high-speed mode. This is followed immediately by an 
additional second-chance high-speed mode, if necessary.
    (1) First-chance idle mode. (i) The mode timer shall start (mt = 0) 
when the vehicle engine speed is between 350 and 1100 rpm. If engine 
speed exceeds 1100 rpm or falls below 350 rpm, the mode timer shall 
reset to zero and resume timing. The minimum idle mode length shall be 
determined as described in paragraph (II)(c)(1)(ii) of this appendix. 
The maximum idle mode length shall be 90 seconds elapsed time (mt = 90).
    (ii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the mode terminated as follows:
    (A) The vehicle shall pass the idle mode and the mode shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the mode shall be 
terminated at the end of an elapsed time of 30 seconds (mt = 30) if, 
prior to that time, the criteria of paragraph (II)(c)(1)(ii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(II)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the mode shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt = 30) and 90 seconds (mt = 90), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (II)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the mode shall be 
terminated if none of the provisions of paragraphs (II)(c)(1)(ii)(A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 90 
seconds (mt = 90). Alternatively, the vehicle may be failed if the 
provisions of paragraphs (II)(c)(2)(i) and (ii) of this appendix are not 
met within an elapsed time of 30 seconds.
    (E) Optional. The vehicle may fail the first-chance test and the 
second-chance test shall be omitted if no exhaust gas concentration less 
than 1800 ppm HC is found by an elapsed time of 30 seconds (mt = 30).
    (2) First-chance and second-chance high-speed modes. This mode 
includes both the first-chance and second-chance high-speed modes, and 
follows immediately upon termination of the first-chance idle mode.
    (i) The mode timer shall reset (mt = 0) when the vehicle engine 
speed is between 2200 and 2800 rpm. If engine speed falls below 2200 rpm 
or exceeds 2800 rpm for more than two seconds in one excursion, or more 
than six seconds over all excursions within 30 seconds of the final 
measured value used in the pass/fail determination, the measured value 
shall be invalidated and the mode continued. If any excursion lasts for 
more than ten seconds, the mode timer shall reset to zero (mt = 0) and 
timing resumed. The minimum high-speed mode length shall be determined 
as described under paragraphs (II)(c)(2)(ii) and (iii) of this appendix. 
The maximum high-speed mode length shall be 180 seconds elapsed time (mt 
= 180).
    (ii) Ford Motor Company and Honda vehicles. For 1981-1987 model year 
Ford Motor Company vehicles and 1984-1985 model year Honda Preludes, the 
pass/fail analysis shall begin after an elapsed time of 10 seconds (mt

[[Page 368]]

= 10) using the following procedure. This procedure may also be used for 
1988-1989 Ford Motor Company vehicles but should not be used for other 
vehicles.
    (A) A pass or fail determination, as described below, shall be used, 
for vehicles that passed the idle mode, to determine whether the high-
speed test should be terminated prior to or at the end of an elapsed 
time of 180 seconds (mt = 180).
    (1) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), the measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (2) The vehicle shall pass the high-speed mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt = 30) if, 
prior to that time, the criteria of paragraph (II)(c)(2)(ii)(A)(1) of 
this appendix are not satisfied, and the measured values are less than 
or equal to the applicable short test standards as described in 
paragraph (II)(a)(2) of this appendix.
    (3) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt = 30) and 180 seconds (mt = 180), the measured values are 
less than or equal to the applicable short test standards as described 
in paragraph (II)(a)(2) of this appendix.
    (4) Restart. If at an elapsed time of 90 seconds (mt = 90) the 
measured values are greater than the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix, the vehicle's engine 
shall be shut off for not more than 10 seconds after returning to idle 
and then shall be restarted. The probe may be removed from the tailpipe 
or the sample pump turned off if necessary to reduce analyzer fouling 
during the restart procedure. The mode timer will stop upon engine shut 
off (mt = 90) and resume upon engine restart. The pass/fail 
determination shall resume as follows after 100 seconds have elapsed (mt 
= 100).
    (i) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 100 
seconds (mt = 100) and 180 seconds (mt = 180), the measured values are 
less than or equal to the applicable short test standards described in 
paragraph (II)(a)(2) of this appendix.
    (ii) The vehicle shall fail the high-speed mode and the test shall 
be terminated if paragraph (II)(c)(2)(ii)(A)(4)(i) of this appendix is 
not satisfied by an elapsed time of 180 seconds (mt = 180).
    (B) A pass or fail determination shall be made for vehicles that 
failed the idle mode and the high-speed mode terminated at the end of an 
elapsed time of 180 seconds (mt = 180) as follows:
    (1) The vehicle shall pass the high-speed mode and the mode shall be 
terminated at an elapsed time of 180 seconds (mt = 180) if any measured 
values of HC and CO exhaust gas concentrations during the high-speed 
mode are less than or equal to the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix.
    (2) Restart. If at an elapsed time of 90 seconds (mt = 90) the 
measured values of HC and CO exhaust gas concentrations during the high-
speed mode are greater than the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix, the vehicle's engine 
shall be shut off for not more than 10 seconds after returning to idle 
and then shall be restarted. The probe may be removed from the tailpipe 
or the sample pump turned off if necessary to reduce analyzer fouling 
during the restart procedure. The mode timer will stop upon engine shut 
off (mt = 90) and resume upon engine restart. The pass/fail 
determination shall resume as follows after 100 seconds have elapsed (mt 
= 100).
    (i) The vehicle shall pass the high-speed mode and the mode shall be 
terminated at an elapsed time of 180 seconds (mt = 180) if any measured 
values of HC and CO exhaust gas concentrations during the high-speed 
mode are less than or equal to the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix.
    (ii) The vehicle shall fail the high-speed mode and the test shall 
be terminated if paragraph (II)(c)(2)(ii)(B)(2)(i) of this appendix is 
not satisfied by an elapsed time of 180 seconds (mt = 180).
    (iii) All other light-duty motor vehicles. The pass/fail analysis 
for vehicles not specified in paragraph (II)(c)(2)(ii) of this appendix 
shall begin after an elapsed time of 10 seconds (mt = 10) using the 
following procedure.
    (A) A pass or fail determination, as described below, shall be used 
for vehicles that passed the idle mode, to determine whether the high-
speed mode should be terminated prior to or at the end of an elapsed 
time of 180 seconds (mt = 180).
    (1) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), any measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (2) The vehicle shall pass the high-speed mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt = 30) if, 
prior to that time, the criteria of paragraph (II)(c)(2)(iii)(A)(1) of 
this appendix are not satisfied, and the measured values are less than 
or equal to the applicable short test standards as described in 
paragraph (II)(a)(2) of this appendix.
    (3) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, at any point between an elapsed

[[Page 369]]

time of 30 seconds (mt = 30) and 180 seconds (mt = 180), the measured 
values are less than or equal to the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix.
    (4) The vehicle shall fail the high-speed mode and the test shall be 
terminated if none of the provisions of paragraphs 
(II)(c)(2)(iii)(A)(1), (2), and (3) of this appendix is satisfied by an 
elapsed time of 180 seconds (mt = 180).
    (B) A pass or fail determination shall be made for vehicles that 
failed the idle mode and the high-speed mode terminated at the end of an 
elapsed time of 180 seconds (mt = 180) as follows:
    (1) The vehicle shall pass the high-speed mode and the mode shall be 
terminated at an elapsed time of 180 seconds (mt = 180) if any measured 
values are less than or equal to the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix.
    (2) The vehicle shall fail the high-speed mode and the test shall be 
terminated if paragraph (II)(c)(2)(iii)(B)(1) of this appendix is not 
satisfied by an elapsed time of 180 seconds (mt = 180).
    (d) Second-chance idle mode. If the vehicle fails the first-chance 
idle mode and passes the high-speed mode, the test timer shall reset to 
zero (tt = 0) and a second-chance idle mode shall commence. The second-
chance idle mode shall have an overall maximum test time of 145 seconds 
(tt = 145). The test shall consist of an idle mode only.
    (1) The engines of 1981-1987 Ford Motor Company vehicles and 1984-
1985 Honda Preludes shall be shut off for not more than 10 seconds and 
restarted. The probe may be removed from the tailpipe or the sample pump 
turned off if necessary to reduce analyzer fouling during the restart 
procedure. This procedure may also be used for 1988-1989 Ford Motor 
Company vehicles but should not be used for other vehicles.
    (2) The mode timer shall start (mt = 0) when the vehicle engine 
speed is between 350 and 1100 rpm. If the engine speed exceeds 1100 rpm 
or falls below 350 rpm the mode timer shall reset to zero and resume 
timing. The minimum second-chance idle mode length shall be determined 
as described in paragraph (II)(d)(3) of this appendix. The maximum 
second-chance idle mode length shall be 90 seconds elapsed time (mt = 
90).
    (3) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the second-chance idle mode shall be terminated as follows:
    (i) The vehicle shall pass the second-chance idle mode and the test 
shall be immediately terminated if, prior to an elapsed time of 30 
seconds (mt = 30), any measured values are less than or equal to 100 ppm 
HC and 0.5 percent CO.
    (ii) The vehicle shall pass the second-chance idle mode and the test 
shall be terminated at the end of an elapsed time of 30 seconds (mt = 
30) if, prior to that time, the criteria of paragraph (II)(d)(3)(i) of 
this appendix are not satisfied, and the measured values are less than 
or equal to the applicable short test standards as described in 
paragraph (II)(a)(2) of this appendix.
    (iii) The vehicle shall pass the second-chance idle mode and the 
test shall be immediately terminated if, at any point between an elapsed 
time of 30 seconds (mt = 30) and 90 seconds (mt = 90), the measured 
values are less than or equal to the applicable short test standards as 
described in paragraph (II)(a)(2) of this appendix.
    (iv) The vehicle shall fail the second-chance idle mode and the test 
shall be terminated if none of the provisions of paragraph 
(II)(d)(3)(i), (ii), and (iii) of this appendix is satisfied by an 
elapsed time of 90 seconds (mt = 90).

                            (III) Loaded Test

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a minimum rate of two times per second. The measured value 
for pass/fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart and the measured 
value for HC and CO as described in paragraph (III)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
values for HC and CO are below or equal to the applicable short test 
standards. A vehicle shall fail the test mode if the values for either 
HC or CO, or both, in all simultaneous pairs of values are above the 
applicable standards.
    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) The test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a loaded 
mode using a chassis dynamometer followed immediately by an idle mode as 
described under paragraphs (III)(c)(1) and (2) of this appendix.

[[Page 370]]

    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The dynamometer shall be warmed up, in stabilized operating 
condition, adjusted, and calibrated in accordance with the procedures of 
appendix A to this subpart. Prior to each test, variable-curve 
dynamometers shall be checked for proper setting of the road-load 
indicator or road-load controller.
    (ii) The vehicle shall be tested in as-received condition with all 
accessories turned off. The engine shall be at normal operating 
temperature (as indicated by a temperature gauge, temperature lamp, 
touch test on the radiator hose, or other visual observation for 
overheating).
    (iii) The vehicle shall be operated during each mode of the test 
with the gear selector in the following position:
    (A) In drive for automatic transmissions and in second (or third if 
more appropriate) for manual transmissions for the loaded mode;
    (B) In park or neutral for the idle mode.
    (iv) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle in accordance with the analyzer manufacturer's 
instructions. For 1996 and newer model year vehicles the OBD data link 
connector will be used to monitor RPM. In the event that an OBD data 
link connector is not available or that an RPM signal is not available 
over the data link connector, a tachometer shall be used instead.
    (v) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (vi) The measured concentration of CO plus CO2 shall be 
greater than or equal to six percent.
    (c) Overall test procedure. The test timer shall start (tt = 0) when 
the conditions specified in paragraph (III)(b)(2) of this appendix are 
met and the mode timer initiates as specified in paragraph (III)(c)(1) 
of this appendix. The test sequence shall have an overall maximum test 
time of 240 seconds (tt = 240). The test shall be immediately terminated 
upon reaching the overall maximum test time.
    (1) Loaded mode--(i) Ford Motor Company and Honda vehicles. 
(Optional) The engines of 1981-1987 Ford Motor Company vehicles and 
1984-1985 Honda Preludes shall be shut off for not more than 10 seconds 
and restarted. This procedure may also be used for 1988-1989 Ford Motor 
Company vehicles but should not be used for other vehicles. The probe 
may be removed from the tailpipe or the sample pump turned off if 
necessary to reduce analyzer fouling during the restart procedure.
    (ii) The mode timer shall start (mt = 0) when the dynamometer speed 
is within the limits specified for the vehicle engine size according to 
the following schedule. If the dynamometer speed falls outside the 
limits for more than five seconds in one excursion, or 15 seconds over 
all excursions, the mode timer shall reset to zero and resume timing. 
The minimum mode length shall be determined as described in paragraph 
(III)(c)(1)(iii)(A) of this appendix. The maximum mode length shall be 
90 seconds elapsed time (mt = 90).

                        Dynamometer Test Schedule
------------------------------------------------------------------------
                                                               Normal
                                                Roll speed     loading
       Gasoline engine size (cylinders)            (mph)       (brake
                                                             horsepower)
------------------------------------------------------------------------
4 or less.....................................       22-25  2.8-4.1
5-6...........................................       29-32  6.8-8.4
7 or more.....................................       32-35  8.4-10.8
------------------------------------------------------------------------

    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the loaded mode and the mode shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt = 30) and 90 seconds (mt = 90), measured values are less 
than or equal to the applicable short test standards described in 
paragraph (a)(2) of this section.
    (B) The vehicle shall fail the loaded mode and the mode shall be 
terminated if paragraph (III)(c)(1)(iii)(A) of this appendix is not 
satisfied by an elapsed time of 90 seconds (mt = 90).
    (C) Optional. The vehicle may fail the loaded mode and any 
subsequent idle mode shall be omitted if no exhaust gas concentration 
less than 1800 ppm HC is found by an elapsed time of 30 seconds (mt = 
30).
    (2) Idle mode--(i) Ford Motor Company and Honda vehicles. (Optional) 
The engines of 1981-1987 Ford Motor Company vehicles and 1984-1985 Honda 
Preludes shall be shut off for not more than 10 seconds and restarted. 
This procedure may also be used for 1988-1989 Ford Motor Company 
vehicles but should not be used for other vehicles. The probe may be 
removed from the tailpipe or the sample pump turned off if necessary to 
reduce analyzer fouling during the restart procedure.
    (ii) The mode timer shall start (mt = 0) when the dynamometer speed 
is zero and the vehicle engine speed is between 350 and 1100 rpm. If 
engine speed exceeds 1100 rpm or falls below 350 rpm, the mode timer 
shall reset to zero and resume timing. The minimum idle mode length 
shall be determined as described in paragraph (II)(c)(2)(ii) of this 
appendix. The maximum idle mode length shall be 90 seconds elapsed time 
(mt = 90).
    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:

[[Page 371]]

    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt = 30) if, 
prior to that time, the criteria of paragraph (III)(c)(2)(iii)(A) of 
this appendix are not satisfied, and the measured values are less than 
or equal to the applicable short test standards as described in 
paragraph (III)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt = 30) and 90 seconds (mt = 90), measured values are less 
than or equal to the applicable short test standards described in 
paragraph (III)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (III)(c)(2)(iii)(A), 
(c)(2)(iii)(B), and (c)(2)(iii)(C) of this appendix is satisfied by an 
elapsed time of 90 seconds (mt = 90).

                      (IV) Preconditioned IDLE TEST

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a minimum rate of two times per second. The measured value 
for pass/fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart, and the measured 
value for HC and CO as described in paragraph (IV)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
values for HC and CO are below or equal to the applicable short test 
standards. A vehicle shall fail the test mode if the values for either 
HC or CO, or both, in all simultaneous pairs of values are above the 
applicable standards.
    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) The test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a first-
chance test and a second-chance test as follows:
    (i) The first-chance test, as described under paragraph (IV)(c) of 
this appendix, shall consist of a preconditioning mode followed by an 
idle mode.
    (ii) The second-chance test, as described under paragraph (IV)(d) of 
this appendix, shall be performed only if the vehicle fails the first-
chance test.
    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The vehicle shall be tested in as-received condition with the 
transmission in neutral or park and all accessories turned off. The 
engine shall be at normal operating temperature (as indicated by a 
temperature gauge, temperature lamp, touch test on the radiator hose, or 
other visual observation for overheating).
    (ii) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle in accordance with the analyzer manufacturer's 
instructions. For 1996 and newer model year vehicles the OBD data link 
connector will be used to monitor RPM. In the event that an OBD data 
link connector is not available or that an RPM signal is not available 
over the data link connector, a tachometer shall be used instead.
    (iii) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (iv) The measured concentration of CO plus CO2 shall be greater than 
or equal to six percent.
    (c) First-chance test. The test timer shall start (tt = 0) when the 
conditions specified in paragraph (IV)(b)(2) of this appendix are met. 
The test shall have an overall maximum test time of 200 seconds (tt = 
200). The first-chance test shall consist of a preconditioning mode 
followed immediately by an idle mode.
    (1) Preconditioning mode. The mode timer shall start (mt = 0) when 
the engine speed is between 2200 and 2800 rpm. The mode shall continue 
for an elapsed time of 30 seconds (mt = 30). If engine speed falls below 
2200 rpm or exceeds 2800 rpm for more than five seconds in any one 
excursion, or 15 seconds over all excursions, the mode timer shall reset 
to zero and resume timing.
    (2) Idle mode. (i) The mode timer shall start (mt = 0) when the 
vehicle engine speed is between 350 and 1100 rpm. If engine speed 
exceeds 1100 rpm or falls below 350 rpm, the mode timer shall reset to 
zero and resume timing. The minimum idle mode length shall be determined 
as described in paragraph (IV)(c)(2)(ii) of this appendix. The maximum 
idle mode length shall be 90 seconds elapsed time (mt = 90).
    (ii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A

[[Page 372]]

pass or fail determination shall be made for the vehicle and the mode 
shall be terminated as follows:
    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt = 30) if, 
prior to that time, the criteria of paragraph (IV)(c)(2)(ii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(IV)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt = 30) and 90 seconds (mt = 90), measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (IV)(a)(2) of this section.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (IV)(c)(2)(ii)(A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 90 
seconds (mt = 90). Alternatively, the vehicle may be failed if the 
provisions of paragraphs (IV)(c)(2) (i) and (ii) of this appendix are 
not met within an elapsed time of 30 seconds.
    (E) Optional. The vehicle may fail the first-chance test and the 
second-chance test shall be omitted if no exhaust gas concentration less 
than 1800 ppm HC is found at an elapsed time of 30 seconds (mt = 30).
    (d) Second-chance test. If the vehicle fails the first-chance test, 
the test timer shall reset to zero and a second-chance test shall be 
performed. The second-chance test shall have an overall maximum test 
time of 425 seconds. The test shall consist of a preconditioning mode 
followed immediately by an idle mode.
    (1) Preconditioning mode. The mode timer shall start (mt = 0) when 
engine speed is between 2200 and 2800 rpm. The mode shall continue for 
an elapsed time of 180 seconds (mt = 180). If the engine speed falls 
below 2200 rpm or exceeds 2800 rpm for more than five seconds in any one 
excursion, or 15 seconds over all excursions, the mode timer shall reset 
to zero and resume timing.
    (2) Idle mode--(i) Ford Motor Company and Honda vehicles. The 
engines of 1981-1987 Ford Motor Company vehicles and 1984-1985 Honda 
Preludes shall be shut off for not more than 10 seconds and then shall 
be restarted. The probe may be removed from the tailpipe or the sample 
pump turned off if necessary to reduce analyzer fouling during the 
restart procedure. This procedure may also be used for 1988-1989 Ford 
Motor Company vehicles but should not be used for other vehicles.
    (ii) The mode timer shall start (mt = 0) when the vehicle engine 
speed is between 350 and 1100 rpm. If the engine speed exceeds 1100 rpm 
or falls below 350 rpm, the mode timer shall reset to zero and resume 
timing. The minimum idle mode length shall be determined as described in 
paragraph (IV)(d)(2)(iii) of this appendix. The maximum idle mode length 
shall be 90 seconds elapsed time (mt = 90).
    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt = 30) if, 
prior to that time, the criteria of paragraph (IV)(d)(2)(iii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(IV)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt = 30) and 90 seconds (mt = 90), measured values are less 
than or equal to the applicable short test standards described in 
paragraph (IV)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (IV)(d)(2)(iii) (A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 90 
seconds (mt = 90).

                (V) Idle Test With Loaded Preconditioning

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a minimum rate of two times per second. The measured value 
for pass/fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart, and the measured 
value for HC and CO as described in paragraph (V)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
values for HC and CO are below or equal to the applicable short test 
standards. A vehicle shall fail the test mode if the values for either 
HC or CO, or both, in all simultaneous pairs of values are above the 
applicable standards.

[[Page 373]]

    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) The test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a first-
chance test and a second-chance test as follows:
    (i) The first-chance test, as described under paragraph (V)(c) of 
this appendix, shall consist of an idle mode.
    (ii) The second-chance test as described under paragraph (V)(d) of 
this appendix shall be performed only if the vehicle fails the first-
chance test.
    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The dynamometer shall be warmed up, in stabilized operating 
condition, adjusted, and calibrated in accordance with the procedures of 
appendix A to this subpart. Prior to each test, variable-curve 
dynamometers shall be checked for proper setting of the road-load 
indicator or road-load controller.
    (ii) The vehicle shall be tested in as-received condition with all 
accessories turned off. The engine shall be at normal operating 
temperature (as indicated by a temperature gauge, temperature lamp, 
touch test on the radiator hose, or other visual observation for 
overheating).
    (iii) The vehicle shall be operated during each mode of the test 
with the gear selector in the following position:
    (A) In drive for automatic transmissions and in second (or third if 
more appropriate) for manual transmissions for the loaded 
preconditioning mode;
    (B) In park or neutral for the idle mode.
    (iv) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle in accordance with the analyzer manufacturer's 
instructions. For 1996 and newer model year vehicles the OBD data link 
connector will be used to monitor RPM. In the event that an OBD data 
link connector is not available or that an RPM signal is not available 
over the data link connector, a tachometer shall be used instead.
    (v) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (vi) The measured concentration of CO plus CO2 shall be 
greater than or equal to six percent.
    (c) First-chance test. The test timer shall start (tt = 0) when the 
conditions specified in paragraph (V)(b)(2) of this appendix are met. 
The test shall have an overall maximum test time of 155 seconds (tt = 
155). The first-chance test shall consist of an idle mode only.
    (1) The mode timer shall start (mt = 0) when the vehicle engine 
speed is between 350 and 1100 rpm. If the engine speed exceeds 1100 rpm 
or falls below 350 rpm, the mode timer shall reset to zero and resume 
timing. The minimum mode length shall be determined as described in 
paragraph (V)(c)(2) of this appendix. The maximum mode length shall be 
90 seconds elapsed time (mt = 90).
    (2) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (i) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (ii) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt = 30) if, 
prior to that time, the criteria of paragraph (V)(c)(2)(i) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(V)(a)(2) of this appendix.
    (iii) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt = 30) and 90 seconds (mt = 90), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (V)(a)(2) of this appendix.
    (iv) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (V)(c)(2)(i), (ii), 
and (iii) of this appendix is satisfied by an elapsed time of 90 seconds 
(mt = 90). Alternatively, the vehicle may be failed if the provisions of 
paragraphs (V)(c)(2) (i) and (ii) of this appendix are not met within an 
elapsed time of 30 seconds.
    (v) Optional. The vehicle may fail the first-chance test and the 
second-chance test shall be omitted if no exhaust gas concentration less 
than 1800 ppm HC is found at an elapsed time of 30 seconds (mt = 30).
    (d) Second-chance test. If the vehicle fails the first-chance test, 
the test timer shall reset to zero (tt = 0) and a second-chance test 
shall be performed. The second-chance test shall have an overall maximum 
test time of 200 seconds (tt = 200). The test shall consist of a 
preconditioning mode using a chassis dynamometer, followed immediately 
by an idle mode.
    (1) Preconditioning mode. The mode timer shall start (mt = 0) when 
the dynamometer speed is within the limits specified for the

[[Page 374]]

vehicle engine size in accordance with the following schedule. The mode 
shall continue for a minimum elapsed time of 30 seconds (mt = 30). If 
the dynamometer speed falls outside the limits for more than five 
seconds in one excursion, or 15 seconds over all excursions, the mode 
timer shall reset to zero and resume timing.

------------------------------------------------------------------------
                                                      Dynamometer test
                                                          schedule
                                                   ---------------------
         Gasoline engine size (cylinders)                       Normal
                                                      Roll     loading
                                                     speed      (brake
                                                     (mph)   horsepower)
------------------------------------------------------------------------
4 or less.........................................    22-25  2.8-4.1
5-6...............................................    29-32  6.8-8.4
7 or more.........................................    32-35  8.4-10.8
------------------------------------------------------------------------

    (2) Idle mode. (i) Ford Motor Company and Honda vehicles. (Optional) 
The engines of 1981-1987 Ford Motor Company vehicles and 1984-1985 Honda 
Preludes shall be shut off for not more than 10 seconds and restarted. 
This procedure may also be used for 1988-1989 Ford Motor Company 
vehicles but should not be used for other vehicles. The probe may be 
removed from the tailpipe or the sample pump turned off if necessary to 
reduce analyzer fouling during the restart procedure.
    (ii) The mode timer shall start (mt = 0) when the dynamometer speed 
is zero and the vehicle engine speed is between 350 and 1100 rpm. If the 
engine speed exceeds 1100 rpm or falls below 350 rpm, the mode timer 
shall reset to zero and resume timing. The minimum idle mode length 
shall be determined as described in paragraph (V)(d)(2)(ii) of this 
appendix. The maximum idle mode length shall be 90 seconds elapsed time 
(mt = 90).
    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt = 30) if, 
prior to that time, the criteria of paragraph (V)(d)(2)(ii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(V)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt = 30) and 90 seconds (mt = 90), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (V)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (V)(d)(2)(ii)(A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 90 
seconds (mt = 90).

                 (VI) Preconditioned Two Speed Idle Test

    (a) General requirements--(1) Exhaust gas sampling algorithm. The 
analysis of exhaust gas concentrations shall begin 10 seconds after the 
applicable test mode begins. Exhaust gas concentrations shall be 
analyzed at a minimum rate of two times per second. The measured value 
for pass/fail determinations shall be a simple running average of the 
measurements taken over five seconds.
    (2) Pass/fail determination. A pass or fail determination shall be 
made for each applicable test mode based on a comparison of the short 
test standards contained in appendix C to this subpart, and the measured 
value for HC and CO as described in paragraph (VI)(a)(1) of this 
appendix. A vehicle shall pass the test mode if any pair of simultaneous 
values for HC and CO are below or equal to the applicable short test 
standards. A vehicle shall fail the test mode if the values for either 
HC or CO, or both, in all simultaneous pairs of values are above the 
applicable standards.
    (3) Void test conditions. The test shall immediately end and any 
exhaust gas measurements shall be voided if the measured concentration 
of CO plus CO2 falls below six percent or the vehicle's 
engine stalls at any time during the test sequence.
    (4) Multiple exhaust pipes. Exhaust gas concentrations from vehicle 
engines equipped with multiple exhaust pipes shall be sampled 
simultaneously.
    (5) The test shall be immediately terminated upon reaching the 
overall maximum test time.
    (b) Test sequence. (1) The test sequence shall consist of a first-
chance test and a second-chance test as follows:
    (i) The first-chance test, as described under paragraph (VI)(c) of 
this appendix, shall consist of a first-chance high-speed mode followed 
immediately by a first-chance idle mode.
    (ii) The second-chance test as described under paragraph (VI)(d) of 
this appendix shall be performed only if the vehicle fails the first-
chance test.
    (2) The test sequence shall begin only after the following 
requirements are met:
    (i) The vehicle shall be tested in as-received condition with the 
transmission in neutral or park and all accessories turned off. The 
engine shall be at normal operating temperature (as indicated by a 
temperature gauge, temperature lamp, touch test on the radiator hose, or 
other visual observation for overheating).

[[Page 375]]

    (ii) For all pre-1996 model year vehicles, a tachometer shall be 
attached to the vehicle in accordance with the analyzer manufacturer's 
instructions. For 1996 and newer model year vehicles the OBD data link 
connector will be used to monitor rpm. In the event that an OBD data 
link connector is not available or that an rpm signal is not available 
over the data link connector, a tachometer shall be used instead.
    (iii) The sample probe shall be inserted into the vehicle's tailpipe 
to a minimum depth of 10 inches. If the vehicle's exhaust system 
prevents insertion to this depth, a tailpipe extension shall be used.
    (iv) The measured concentration of CO plus CO2 shall be 
greater than or equal to six percent.
    (c) First-chance test. The test timer shall start (tt = 0) when the 
conditions specified in paragraph (VI)(b)(2) of this appendix are met. 
The test shall have an overall maximum test time of 290 seconds (tt = 
290). The first-chance test shall consist of a high-speed mode followed 
immediately by an idle mode.
    (1) First-chance high-speed mode. (i) The mode timer shall reset (mt 
= 0) when the vehicle engine speed is between 2200 and 2800 rpm. If the 
engine speed falls below 2200 rpm or exceeds 2800 rpm for more than two 
seconds in one excursion, or more than six seconds over all excursions 
within 30 seconds of the final measured value used in the pass/fail 
determination, the measured value shall be invalidated and the mode 
continued. If any excursion lasts for more than ten seconds, the mode 
timer shall reset to zero (mt = 0) and timing resumed. The high-speed 
mode length shall be 90 seconds elapsed time (mt = 90).
    (ii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the high-speed mode and the mode shall be 
terminated at an elapsed time of 90 seconds (mt = 90) if any measured 
values are less than or equal to the applicable short test standards as 
described in paragraph (VI)(a)(2) of this appendix.
    (B) The vehicle shall fail the high-speed mode and the mode shall be 
terminated if the requirements of paragraph (VI)(c)(1)(ii)(A) of this 
appendix are not satisfied by an elapsed time of 90 seconds (mt = 90).
    (C) Optional. The vehicle shall fail the first-chance test and any 
subsequent test shall be omitted if no exhaust gas concentration lower 
than 1800 ppm HC is found at an elapsed time of 30 seconds (mt = 30).
    (2) First-chance idle mode. (i) The mode timer shall start (mt = 0) 
when the vehicle engine speed is between 350 and 1100 rpm. If the engine 
speed exceeds 1100 rpm or falls below 350 rpm, the mode timer shall 
reset to zero and resume timing. The minimum first-chance idle mode 
length shall be determined as described in paragraph (VI)(c)(2)(ii) of 
this appendix. The maximum first-chance idle mode length shall be 90 
seconds elapsed time (mt = 90).
    (ii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the idle mode and the test shall be 
terminated at the end of an elapsed time of 30 seconds (mt = 30) if, 
prior to that time, the criteria of paragraph (VI)(c)(2)(ii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(VI)(a)(2) of this appendix.
    (C) The vehicle shall pass the idle mode and the test shall be 
immediately terminated if, at any point between an elapsed time of 30 
seconds (mt = 30) and 90 seconds (mt = 90), the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (VI)(a)(2) of this appendix.
    (D) The vehicle shall fail the idle mode and the test shall be 
terminated if none of the provisions of paragraphs (VI)(c)(2)(ii) (A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 90 
seconds (mt = 90). Alternatively, the vehicle may be failed if the 
provisions of paragraphs (VI)(c)(2)(i) and (ii) of this appendix are not 
met within the elapsed time of 30 seconds.
    (d) Second-chance test. (1) If the vehicle fails either mode of the 
first-chance test, the test timer shall reset to zero (tt = 0) and a 
second-chance test shall commence. The second-chance test shall be 
performed based on the first-chance test failure mode or modes as 
follows:
    (A) If the vehicle failed only the first-chance high-speed mode, the 
second-chance test shall consist of a second-chance high-speed mode as 
described in paragraph (VI)(d)(2) of this appendix. The overall maximum 
test time shall be 280 seconds (tt = 280).
    (B) If the vehicle failed only the first-chance idle mode, the 
second-chance test shall consist of a second-chance pre-conditioning 
mode followed immediately by a second-chance idle mode as described in 
paragraphs (VI)(d) (3) and (4) of this appendix. The overall maximum 
test time shall be 425 seconds (tt = 425).
    (C) If both the first-chance high-speed mode and first-chance idle 
mode were failed, the second-chance test shall consist of the

[[Page 376]]

second-chance high-speed mode followed immediately by the second-chance 
idle mode as described in paragraphs (VI)(d) (2) and (4) of this 
appendix. However, if during this second-chance procedure the vehicle 
fails the second-chance high-speed mode, then the second-chance idle 
mode may be eliminated. The overall maximum test time shall be 425 
seconds (tt = 425).
    (2) Second-chance high-speed mode--(i) Ford Motor Company and Honda 
vehicles. The engines of 1981-1987 Ford Motor Company vehicles and 1984-
1985 Honda Preludes shall be shut off for not more than 10 seconds and 
then shall be restarted. The probe may be removed from the tailpipe or 
the sample pump turned off if necessary to reduce analyzer fouling 
during the restart procedure. This procedure may also be used for 1988-
1989 Ford Motor Company vehicles but should not be used for other 
vehicles.
    (ii) The mode timer shall reset (mt = 0) when the vehicle engine 
speed is between 2200 and 2800 rpm. If the engine speed falls below 2200 
rpm or exceeds 2800 rpm for more than two seconds in one excursion, or 
more than six seconds over all excursions within 30 seconds of the final 
measured value used in the pass/fail determination, the measured value 
shall be invalidated and the mode continued. The minimum second-chance 
high-speed mode length shall be determined as described in paragraphs 
(VI)(d)(2) (iii) and (iv) of this appendix. If any excursion lasts for 
more than ten seconds, the mode timer shall reset to zero (mt = 0) and 
timing resumed. The maximum second-chance high-speed mode length shall 
be 180 seconds elapsed time (mt = 180).
    (iii) In the case where the second-chance high-speed mode is not 
followed by the second-chance idle mode, the pass/fail analysis shall 
begin after an elapsed time of 10 seconds (mt = 10). A pass or fail 
determination shall be made for the vehicle and the mode shall be 
terminated as follows:
    (A) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, prior to an elapsed time of 30 seconds (mt = 
30), measured values are less than or equal to 100 ppm HC and 0.5 
percent CO.
    (B) The vehicle shall pass the high-speed mode and the test shall be 
terminated if at the end of an elapsed time of 30 seconds (mt = 30) if, 
prior to that time, the criteria of paragraph (VI)(d)(2)(iii)(A) of this 
appendix are not satisfied, and the measured values are less than or 
equal to the applicable short test standards as described in paragraph 
(VI)(a)(2) of this appendix.
    (C) The vehicle shall pass the high-speed mode and the test shall be 
immediately terminated if, at any point between an elapsed time for 30 
seconds (mt = 30) and 180 seconds (mt = 180), the measured values are 
less than or equal to the applicable short test standards as described 
in paragraph (VI)(a)(2) of this appendix.
    (D) The vehicle shall fail the high-speed mode and the test shall be 
terminated if none of the provisions of paragraphs (VI)(d)(2)(iii) (A), 
(B), and (C) of this appendix is satisfied by an elapsed time of 180 
seconds (mt = 180).
    (iv) In the case where the second-chance high-speed mode is followed 
by the second-chance idle mode, the pass/fail analysis shall begin after 
an elapsed time of 10 seconds (mt = 10). A pass or fail determination 
shall be made for the vehicle and the mode shall be terminated as 
follows:
    (A) The vehicle shall pass the high-speed mode and the mode shall be 
terminated at the end of an elapsed time of 180 seconds (mt = 180) if 
any measured values are less than or equal to the applicable short test 
standards as described in paragraph (VI)(a)(2) of this appendix.
    (B) The vehicle shall fail the high-speed mode and the mode shall be 
terminated if paragraph (VI)(d)(2)(iv)(A) of this appendix is not 
satisfied by an elapsed time of 180 seconds (mt = 180).
    (3) Second-chance preconditioning mode. The mode timer shall start 
(mt = 0) when engine speed is between 2200 and 2800 rpm. The mode shall 
continue for an elapsed time of 180 seconds (mt = 180). If the engine 
speed falls below 2200 rpm or exceeds 2800 rpm for more than five 
seconds in any one excursion, or 15 seconds over all excursions, the 
mode timer shall reset to zero and resume timing.
    (4) Second-chance idle mode--(i) Ford Motor Company and Honda 
vehicles. The engines of 1981-1987 Ford Motor Company vehicles and 1984-
1985 Honda Preludes shall be shut off for not more than 10 seconds and 
then shall be restarted. The probe may be removed from the tailpipe or 
the sample pump turned off if necessary to reduce analyzer fouling 
during the restart procedure. This procedure may also be used for 1988-
1989 Ford Motor Company vehicles but should not be used for other 
vehicles.
    (ii) The mode timer shall start (mt = 0) when the vehicle engine 
speed is between 350 and 1100 rpm. If the engine exceeds 1100 rpm or 
falls below 350 rpm the mode timer shall reset to zero and resume 
timing. The minimum second-chance idle mode length shall be determined 
as described in paragraph (VI)(d)(4)(iii) of this appendix. The maximum 
second-chance idle mode length shall be 90 seconds elapsed time (mt = 
90).
    (iii) The pass/fail analysis shall begin after an elapsed time of 10 
seconds (mt = 10). A pass or fail determination shall be made for the 
vehicle and the mode shall be terminated as follows:
    (A) The vehicle shall pass the second-chance idle mode and the test 
shall be immediately terminated if, prior to an elapsed time of 30 
seconds (mt = 30), measured values

[[Page 377]]

are less than or equal to 100 ppm HC and 0.5 percent CO.
    (B) The vehicle shall pass the second-chance idle mode and the test 
shall be terminated at the end of an elapsed time of 30 seconds (mt = 
30) if, prior to that time, the criteria of paragraph (VI)(d)(4)(iii)(A) 
of this appendix are not satisfied, and the measured values are less 
than or equal to the applicable short test standards as described in 
paragraph (VI)(a)(2) of this appendix.
    (C) The vehicle shall pass the second-chance idle mode and the test 
shall be immediately terminated if, at any point between an elapsed time 
of 30 seconds (mt = 30) and 90 seconds (mt = 90), measured values are 
less than or equal to the applicable short test standards described in 
paragraph (VI)(a)(2) of this appendix.
    (D) The vehicle shall fail the second-chance idle mode and the test 
shall be terminated if none of the provisions of paragraphs 
(VI)(d)(4)(iii) (A), (B), and (C) of this appendix is satisfied by an 
elapsed time of 90 seconds (mt = 90).

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40946, Aug. 6, 1996]



    Sec. Appendix C to Subpart S of Part 51--Steady-State Short Test 
                                Standards

   (I) Short Test Standards for 1981 and Later Model Year Light-Duty 
                                Vehicles

    For 1981 and later model year light-duty vehicles for which any of 
the test procedures described in appendix B to this subpart are utilized 
to establish Emissions Performance Warranty eligibility (i.e., 1981 and 
later model year light-duty vehicles at low altitude and 1982 and later 
model year vehicles at high altitude to which high altitude 
certification standards of 1.5 gpm HC and 15 gpm CO or less apply), 
short test emissions for all tests and test modes shall not exceed:
    (a) Hydrocarbons: 220 ppm as hexane.
    (b) Carbon monoxide: 1.2%.

   (II) Short Test Standards for 1981 and Later Model Year Light-Duty 
                                 Trucks

    For 1981 and later model year light-duty trucks for which any of the 
test procedures described in appendix B to this subpart are utilized to 
establish Emissions Performance Warranty eligibility (i.e., 1981 and 
later model year light-duty trucks at low altitude and 1982 and later 
model year trucks at high altitude to which high altitude certification 
standards of 2.0 gpm HC and 26 gpm CO or less apply), short test 
emissions for all tests and test modes shall not exceed:
    (a) Hydrocarbons: 220 ppm as hexane.
    (b) Carbon monoxide: 1.2%.



    Sec. Appendix D to Subpart S of Part 51--Steady-State Short Test 
                                Equipment

              (I) Steady-State Test Exhaust Analysis System

    (a) Sampling system--(1) General requirements. The sampling system 
for steady-state short tests shall, at a minimum, consist of a tailpipe 
probe, a flexible sample line, a water removal system, particulate trap, 
sample pump, flow control components, tachometer or dynamometer, 
analyzers for HC, CO, and CO2, and digital displays for 
exhaust concentrations of HC, CO, and CO2, and engine rpm. 
Materials that are in contact with the gases sampled shall not 
contaminate or change the character of the gases to be analyzed, 
including gases from alcohol fueled vehicles. The probe shall be capable 
of being inserted to a depth of at least ten inches into the tailpipe of 
the vehicle being tested, or into an extension boot if one is used. A 
digital display for dynamometer speed and load shall be included if the 
test procedures described in appendix B to this subpart, paragraphs 
(III) and (V), are conducted. Minimum specifications for optional NO 
analyzers are also described in this appendix. The analyzer system shall 
be able to test, as specified in at least one section in appendix B to 
this subpart, all model vehicles in service at the time of sale of the 
analyzer.
    (2) Temperature operating range. The sampling system and all 
associated hardware shall be of a design certified to operate within the 
performance specifications described in paragraph (I)(b) of this 
appendix in ambient air temperatures ranging from 41 to 110 degrees 
Fahrenheit. The analyzer system shall, where necessary, include features 
to keep the sampling system within the specified range.
    (3) Humidity operating range. The sampling system and all associated 
hardware shall be of a design certified to operate within the 
performance specifications described in paragraph (I)(b) of this 
appendix at a minimum of 80 percent relative humidity throughout the 
required temperature range.
    (4) Barometric pressure compensation. Barometric pressure 
compensation shall be provided. Compensation shall be made for 
elevations up to 6,000 feet (above mean sea level). At any given 
altitude and ambient conditions specified in paragraph (I)(b) of this 
appendix, errors due to barometric pressure changes of 2 inches of mercury shall not exceed the accuracy limits 
specified in paragraph (I)(b) of this appendix.
    (5) Dual sample probe requirements. When testing a vehicle with dual 
exhaust pipes, a dual sample probe of a design certified by the analyzer 
manufacturer to provide equal flow in each leg shall be used. The equal 
flow requirement is considered to be met if the flow rate in each leg of 
the probe has been measured under two sample pump flow rates (the

[[Page 378]]

normal rate and a rate equal to the onset of low flow), and if the flow 
rates in each of the legs are found to be equal to each other (within 
15% of the flow rate in the leg having lower flow).
    (6) System lockout during warm-up. Functional operation of the gas 
sampling unit shall remain disabled through a system lockout until the 
instrument meets stability and warm-up requirements. The instrument 
shall be considered ``warmed up'' when the zero and span readings for 
HC, CO, and CO2 have stabilized, within 3% of the full range of low scale, for five minutes 
without adjustment.
    (7) Electromagnetic isolation and interference. Electromagnetic 
signals found in an automotive service environment shall not cause 
malfunctions or changes in the accuracy in the electronics of the 
analyzer system. The instrument design shall ensure that readings do not 
vary as a result of electromagnetic radiation and induction devices 
normally found in the automotive service environment, including high 
energy vehicle ignition systems, radio frequency transmission radiation 
sources, and building electrical systems.
    (8) Vibration and shock protection. System operation shall be 
unaffected by the vibration and shock encountered under the normal 
operating conditions encountered in an automotive service environment.
    (9) Propane equivalency factor. The propane equivalency factor shall 
be displayed in a manner that enables it to be viewed conveniently, 
while permitting it to be altered only by personnel specifically 
authorized to do so.
    (b) Analyzers--(1) Accuracy. The analyzers shall be of a design 
certified to meet the following accuracy requirements when calibrated to 
the span points specified in appendix A to this subpart:

------------------------------------------------------------------------
           Channel               Range    Accuracy  Noise  Repeatability
------------------------------------------------------------------------
HC, ppm.....................  0-400       2 analyzers shall not exceed eight seconds 
to 90% of a step change in input. For NO analyzers, the response time 
shall not exceed twelve seconds to 90% of a step change in input.
    (4) Display refresh rate. Dynamic information being displayed shall 
be refreshed at a minimum rate of twice per second.
    (5) Interference effects. The interference effects for non-interest 
gases shall not exceed 10 ppm for hydrocarbons, 
0.05 percent for carbon monoxide, 0.20 percent for carbon dioxide, and 20 ppm for oxides of nitrogen.
    (6) Low flow indication. The analyzer shall provide an indication 
when the sample flow is below the acceptable level. The sampling system 
shall be equipped with a flow meter (or equivalent) that shall indicate 
sample flow degradation when meter error exceeds three percent of full 
scale, or causes system response time to exceed 13 seconds to 90 percent 
of a step change in input, whichever is less.
    (7) Engine speed detection. The analyzer shall utilize a tachometer 
capable of detecting engine speed in revolutions per minute (rpm) with a 
0.5 second response time and an accuracy of 3% of 
the true rpm.
    (8) Test and mode timers. The analyzer shall be capable of 
simultaneously determining the amount of time elapsed in a test, and in 
a mode within that test.
    (9) Sample rate. The analyzer shall be capable of measuring exhaust 
concentrations of gases specified in this section at a minimum rate of 
twice per second.
    (c) Demonstration of conformity. The analyzer shall be demonstrated 
to the satisfaction of the inspection program manager, through 
acceptance testing procedures, to meet the requirements of this section 
and that it is capable of being maintained as required in appendix A to 
this subpart.

                   (II) Steady-State Test Dynamometer

    (a) The chassis dynamometer for steady-state short tests shall 
provide the following capabilities:
    (1) Power absorption. The dynamometer shall be capable of applying a 
load to the vehicle's driving tire surfaces at the horsepower and speed 
levels specified in paragraph (II)(b) of this appendix.
    (2) Short-term stability. Power absorption at constant speed shall 
not drift more than 0.5 horsepower (hp) during any 
single test mode.
    (3) Roll weight capacity. The dynamometer shall be capable of 
supporting a driving axle weight up to four thousand (4,000) pounds or 
greater.
    (4) Between roll wheel lifts. These shall be controllable and 
capable of lifting a minimum of four thousand (4,000) pounds.
    (5) Roll brakes. Both rolls shall be locked when the wheel lift is 
up.

[[Page 379]]

    (6) Speed indications. The dynamometer speed display shall have a 
range of 0-60 mph, and a resolution and accuracy of at least 1 mph.
    (7) Safety interlock. A roll speed sensor and safety interlock 
circuit shall be provided which prevents the application of the roll 
brakes and upward lift movement at any roll speed above 0.5 mph.
    (b) The dynamometer shall produce the load speed relationships 
specified in paragraphs (III) and (V) of appendix B to this subpart.

           (III) Transient Emission Test Equipment [Reserved]

         (IV) Evaporative System Purge Test Equipment [Reserved]

       (V) Evaporative System Integrity Test Equipment [Reserved]

[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993]



  Sec. Appendix E to Subpart S of Part 51--Transient Test Driving Cycle

    (I) Driver's trace. All excursions in the transient driving cycle 
shall be evaluated by the procedures defined in Sec. 86.115-78(b)(1) 
and Sec. 86.115(c) of this chapter. Excursions exceeding these limits 
shall cause a test to be void. In addition, provisions shall be 
available to utilize cycle validation criteria, as described in Sec. 
86.1341-90 of this chapter, for trace speed versus actual speed as a 
means to determine a valid test.
    (II) Driving cycle. The following table shows the time speed 
relationship for the transient IM240 test procedure.

------------------------------------------------------------------------
                             Second                                MPH
------------------------------------------------------------------------
0..............................................................     0
1..............................................................     0
2..............................................................     0
3..............................................................     0
4..............................................................     0
5..............................................................     3
6..............................................................     5.9
7..............................................................     8.6
8..............................................................    11.5
9..............................................................    14.3
10.............................................................    16.9
11.............................................................    17.3
12.............................................................    18.1
13.............................................................    20.7
14.............................................................    21.7
15.............................................................    22.4
16.............................................................    22.5
17.............................................................    22.1
18.............................................................    21.5
19.............................................................    20.9
20.............................................................    20.4
21.............................................................    19.8
22.............................................................    17
23.............................................................    14.9
24.............................................................    14.9
25.............................................................    15.2
26.............................................................    15.5
27.............................................................    16
28.............................................................    17.1
29.............................................................    19.1
30.............................................................    21.1
31.............................................................    22.7
32.............................................................    22.9
33.............................................................    22.7
34.............................................................    22.6
35.............................................................    21.3
36.............................................................    19
37.............................................................    17.1
38.............................................................    15.8
39.............................................................    15.8
40.............................................................    17.7
41.............................................................    19.8
42.............................................................    21.6
43.............................................................    23.2
44.............................................................    24.2
45.............................................................    24.6
46.............................................................    24.9
47.............................................................    25
48.............................................................    25.7
49.............................................................    26.1
50.............................................................    26.7
51.............................................................    27.5
52.............................................................    28.6
53.............................................................    29.3
54.............................................................    29.8
55.............................................................    30.1
56.............................................................    30.4
57.............................................................    30.7
58.............................................................    30.7
59.............................................................    30.5
60.............................................................    30.4
61.............................................................    30.3
62.............................................................    30.4
63.............................................................    30.8
64.............................................................    30.4
65.............................................................    29.9
66.............................................................    29.5
67.............................................................    29.8
68.............................................................    30.3
69.............................................................    30.7
70.............................................................    30.9
71.............................................................    31
72.............................................................    30.9
73.............................................................    30.4
74.............................................................    29.8
75.............................................................    29.9
76.............................................................    30.2
77.............................................................    30.7
78.............................................................    31.2
79.............................................................    31.8
80.............................................................    32.2
81.............................................................    32.4
82.............................................................    32.2
83.............................................................    31.7
84.............................................................    28.6
85.............................................................    25.1
86.............................................................    21.6
87.............................................................    18.1
88.............................................................    14.6
89.............................................................    11.1
90.............................................................     7.6
91.............................................................     4.1
92.............................................................     0.6
93.............................................................     0
94.............................................................     0
95.............................................................     0
96.............................................................     0
97.............................................................     0
98.............................................................     3.3
99.............................................................     6.6

[[Page 380]]

 
100............................................................     9.9
101............................................................    13.2
102............................................................    16.5
103............................................................    19.8
104............................................................    22.2
105............................................................    24.3
106............................................................    25.8
107............................................................    26.4
108............................................................    25.7
109............................................................    25.1
110............................................................    24.7
111............................................................    25.2
112............................................................    25.4
113............................................................    27.2
114............................................................    26.5
115............................................................    24
116............................................................    22.7
117............................................................    19.4
118............................................................    17.7
119............................................................    17.2
120............................................................    18.1
121............................................................    18.6
122............................................................    20
123............................................................    20.7
124............................................................    21.7
125............................................................    22.4
126............................................................    22.5
127............................................................    22.1
128............................................................    21.5
129............................................................    20.9
130............................................................    20.4
131............................................................    19.8
132............................................................    17
133............................................................    17.1
134............................................................    15.8
135............................................................    15.8
136............................................................    17.7
137............................................................    19.8
138............................................................    21.6
139............................................................    22.2
140............................................................    24.5
141............................................................    24.7
142............................................................    24.8
143............................................................    24.7
144............................................................    24.6
145............................................................    24.6
146............................................................    25.1
147............................................................    25.6
148............................................................    25.7
149............................................................    25.4
150............................................................    24.9
151............................................................    25
152............................................................    25.4
153............................................................    26
154............................................................    26
155............................................................    25.7
156............................................................    26.1
157............................................................    26.7
158............................................................    27.3
159............................................................    30.5
160............................................................    33.5
161............................................................    36.2
162............................................................    37.3
163............................................................    39.3
164............................................................    40.5
165............................................................    42.1
166............................................................    43.5
167............................................................    45.1
168............................................................    46
169............................................................    46.8
170............................................................    47.5
171............................................................    47.5
172............................................................    47.3
173............................................................    47.2
174............................................................    47.2
175............................................................    47.4
176............................................................    47.9
177............................................................    48.5
178............................................................    49.1
179............................................................    49.5
180............................................................    50
181............................................................    50.6
182............................................................    51
183............................................................    51.5
184............................................................    52.2
185............................................................    53.2
186............................................................    54.1
187............................................................    54.6
188............................................................    54.9
189............................................................    55
190............................................................    54.9
191............................................................    54.6
192............................................................    54.6
193............................................................    54.8
194............................................................    55.1
195............................................................    55.5
196............................................................    55.7
197............................................................    56.1
198............................................................    56.3
199............................................................    56.6
200............................................................    56.7
201............................................................    56.7
202............................................................    56.3
203............................................................    56
204............................................................    55
205............................................................    53.4
206............................................................    51.6
207............................................................    51.8
208............................................................    52.1
209............................................................    52.5
210............................................................    53
211............................................................    53.5
212............................................................    54
213............................................................    54.9
214............................................................    55.4
215............................................................    55.6
216............................................................    56
217............................................................    56
218............................................................    55.8
219............................................................    55.2
220............................................................    54.5
221............................................................    53.6
222............................................................    52.5
223............................................................    51.5
224............................................................    50.5
225............................................................    48
226............................................................    44.5
227............................................................    41
228............................................................    37.5
229............................................................    34
230............................................................    30.5
231............................................................    27
232............................................................    23.5
233............................................................    20
234............................................................    16.5
235............................................................    13
236............................................................     9.5
237............................................................     6
238............................................................     2.5
239............................................................     0
------------------------------------------------------------------------


[57 FR 52987, Nov. 5, 1992, as amended at 58 FR 59367, Nov. 9, 1993]

[[Page 381]]



    Subpart T_Conformity to State or Federal Implementation Plans of 
   Transportation Plans, Programs, and Projects Developed, Funded or 
       Approved Under Title 23 U.S.C. or the Federal Transit Laws

    Authority: 42 U.S.C. 7401-7671q.



Sec. 51.390  Implementation plan revision.

    (a) Purpose and applicability. The federal conformity rules under 
part 93, subpart A, of this chapter, in addition to any existing 
applicable state requirements, establish the conformity criteria and 
procedures necessary to meet the requirements of Clean Air Act section 
176(c) until such time as EPA approves the conformity implementation 
plan revision required by this subpart. A state with an area subject to 
this subpart and part 93, subpart A, of this chapter must submit to EPA 
a revision to its implementation plan which contains criteria and 
procedures for DOT, MPOs and other state or local agencies to assess the 
conformity of transportation plans, programs, and projects, consistent 
with this subpart and part 93, subpart A, of this chapter. The federal 
conformity regulations contained in part 93, subpart A, of this chapter 
would continue to apply for the portion of the requirements that the 
state did not include in its conformity implementation plan and the 
portion, if any, of the state's conformity provisions that is not 
approved by EPA. In addition, any previously applicable implementation 
plan conformity requirements remain enforceable until the state submits 
a revision to its applicable implementation plan to specifically remove 
them and that revision is approved by EPA.
    (b) Conformity implementation plan content. To satisfy the 
requirements of Clean Air Act section 176(c)(4)(E), the implementation 
plan revision required by this section must include the following three 
requirements of part 93, subpart A, of this chapter: Sec. Sec. 93.105, 
93.122(a)(4)(ii), and 93.125(c). A state may elect to include any other 
provisions of part 93, subpart A. If the provisions of the following 
sections of part 93, subpart A, of this chapter are included, such 
provisions must be included in verbatim form, except insofar as needed 
to clarify or to give effect to a stated intent in the revision to 
establish criteria and procedures more stringent than the requirements 
stated in this chapter: Sec. Sec. 93.101, 93.102, 93.103, 93.104, 
93.106, 93.109, 93.110, 93.111, 93.112, 93.113, 93.114, 93.115, 93.116, 
93.117, 93.118, 93.119, 93.120, 93.121, 93.126, and 93.127. A state's 
conformity provisions may contain criteria and procedures more stringent 
than the requirements described in this subpart and part 93, subpart A, 
of this chapter only if the state's conformity provisions apply equally 
to non-federal as well as federal entities.
    (c) Timing and approval. A state must submit this revision to EPA by 
November 25, 1994 or within 12 months of an area's redesignation from 
attainment to nonattainment, if the state has not previously submitted 
such a revision. The state must also revise its conformity 
implementation plan within 12 months of the date of publication of any 
final amendments to Sec. Sec. 93.105, 93.122(a)(4)(ii), and 93.125(c), 
as appropriate. Any other portions of part 93, subpart A, of this 
chapter that the state has included in its conformity implementation 
plan and EPA has approved must be revised in the state's implementation 
plan and submitted to EPA within 12 months of the date of publication of 
any final amendments to such sections. EPA will provide DOT with a 30-
day comment period before taking action to approve or disapprove the 
submission. In order for EPA to approve the implementation plan revision 
submitted to EPA under this subpart, the plan revision must address and 
give full legal effect to the following three requirements of part 93, 
subpart A: Sec. Sec. 93.105, 93.122(a)(4)(ii), and 93.125(c). Any other 
provisions that are incorporated into the conformity implementation plan 
must also be done in a manner that gives them full legal effect. 
Following EPA approval of the state conformity provisions (or a portion 
thereof) in a revision to the state's conformity implementation plan, 
conformity determinations will be governed by the approved (or approved 
portion of the) state criteria and procedures as well as any applicable 
portions

[[Page 382]]

of the federal conformity rules that are not addressed by the approved 
conformity SIP.

[73 FR 4438, Jan. 24, 2008]



                  Subpart U_Economic Incentive Programs

    Source: 59 FR 16710, Apr. 7, 1994, unless otherwise noted.



Sec. 51.490  Applicability.

    (a) The rules in this subpart apply to any statutory economic 
incentive program (EIP) submitted to the EPA as an implementation plan 
revision to comply with sections 182(g)(3), 182(g)(5), 187(d)(3), or 
187(g) of the Act. Such programs may be submitted by any authorized 
governmental organization, including States, local governments, and 
Indian governing bodies.
    (b) The provisions contained in these rules, except as explicitly 
exempted, shall also serve as the EPA's policy guidance on discretionary 
EIP's submitted as implementation plan revisions for any purpose other 
than to comply with the statutory requirements specified in paragraph 
(a) of this section.



Sec. 51.491  Definitions.

    Act means the Clean Air Act as amended November 15, 1990.
    Actual emissions means the emissions of a pollutant from an affected 
source determined by taking into account actual emission rates 
associated with normal source operation and actual or representative 
production rates (i.e., capacity utilization and hours of operation).
    Affected source means any stationary, area, or mobile source of a 
criteria pollutant(s) to which an EIP applies. This term applies to 
sources explicitly included at the start of a program, as well as 
sources that voluntarily enter (i.e., opt into) the program.
    Allowable emissions means the emissions of a pollutant from an 
affected source determined by taking into account the most stringent of 
all applicable SIP emissions limits and the level of emissions 
consistent with source compliance with all Federal requirements related 
to attainment and maintenance of the NAAQS and the production rate 
associated with the maximum rated capacity and hours of operation 
(unless the source is subject to federally enforceable limits which 
restrict the operating rate, or hours of operation, or both).
    Area sources means stationary and nonroad sources that are too small 
and/or too numerous to be individually included in a stationary source 
emissions inventory.
    Attainment area means any area of the country designated or 
redesignated by the EPA at 40 CFR part 81 in accordance with section 
107(d) as having attained the relevant NAAQS for a given criteria 
pollutant. An area can be an attainment area for some pollutants and a 
nonattainment area for other pollutants.
    Attainment demonstration means the requirement in section 
182(b)(1)(A) of the Act to demonstrate that the specific annual 
emissions reductions included in a SIP are sufficient to attain the 
primary NAAQS by the date applicable to the area.
    Directionally-sound strategies are strategies for which adequate 
procedures to quantify emissions reductions or specify a program 
baseline are not defined as part of the EIP.
    Discretionary economic incentive program means any EIP submitted to 
the EPA as an implementation plan revision for purposes other than to 
comply with the statutory requirements of sections 182(g)(3), 182(g)(5), 
187(d)(3), or 187(g) of the Act.
    Economic incentive program (EIP) means a program which may include 
State established emission fees or a system of marketable permits, or a 
system of State fees on sale or manufacture of products the use of which 
contributes to O3 formation, or any combination of the 
foregoing or other similar measures, as well as incentives and 
requirements to reduce vehicle emissions and vehicle miles traveled in 
the area, including any of the transportation control measures 
identified in section 108(f). Such programs may be directed toward 
stationary, area, and/or mobile sources, to achieve emissions reductions 
milestones, to attain and maintain ambient air quality standards, and/or 
to provide more flexible,

[[Page 383]]

lower-cost approaches to meeting environmental goals. Such programs are 
categorized into the following three categories: Emission-limiting, 
market-response, and directionally-sound strategies.
    Emission-limiting strategies are strategies that directly specify 
limits on total mass emissions, emission-related parameters (e.g., 
emission rates per unit of production, product content limits), or 
levels of emissions reductions relative to a program baseline that are 
required to be met by affected sources, while providing flexibility to 
sources to reduce the cost of meeting program requirements.
    Indian governing body means the governing body of any tribe, band, 
or group of Indians subject to the jurisdiction of the U.S. and 
recognized by the U.S. as possessing power of self-government.
    Maintenance plan means an implementation plan for an area for which 
the State is currently seeking designation or has previously sought 
redesignation to attainment, under section 107(d) of the Act, which 
provides for the continued attainment of the NAAQS.
    Market-response strategies are strategies that create one or more 
incentives for affected sources to reduce emissions, without directly 
specifying limits on emissions or emission-related parameters that 
individual sources or even all sources in the aggregate are required to 
meet.
    Milestones means the reductions in emissions required to be achieved 
pursuant to section 182(b)(1) and the corresponding requirements in 
section 182(c)(2) (B) and (C), 182(d), and 182(e) of the Act for 
O3 nonattainment areas, as well as the reduction in emissions 
of CO equivalent to the total of the specified annual emissions 
reductions required by December 31, 1995, pursuant to section 187(d)(1).
    Mobile sources means on-road (highway) vehicles (e.g., automobiles, 
trucks and motorcycles) and nonroad vehicles (e.g., trains, airplanes, 
agricultural equipment, industrial equipment, construction vehicles, 
off-road motorcycles, and marine vessels).
    National ambient air quality standard (NAAQS) means a standard set 
by the EPA at 40 CFR part 50 under section 109 of the Act.
    Nonattainment area means any area of the country designated by the 
EPA at 40 CFR part 81 in accordance with section 107(d) of the Act as 
nonattainment for one or more criteria pollutants. An area could be a 
nonattainment area for some pollutants and an attainment area for other 
pollutants.
    Nondiscriminatory means that a program in one State does not result 
in discriminatory effects on other States or sources outside the State 
with regard to interstate commerce.
    Program baseline means the level of emissions, or emission-related 
parameter(s), for each affected source or group of affected sources, 
from which program results (e.g., quantifiable emissions reductions) 
shall be determined.
    Program uncertainty factor means a factor applied to discount the 
amount of emissions reductions credited in an implementation plan 
demonstration to account for any strategy-specific uncertainties in an 
EIP.
    Reasonable further progress (RFP) plan means any incremental 
emissions reductions required by the CAA (e.g., section 182(b)) and 
approved by the EPA as meeting these requirements.
    Replicable refers to methods which are sufficiently unambiguous such 
that the same or equivalent results would be obtained by the application 
of the methods by different users.
    RFP baseline means the total of actual volatile organic compounds or 
nitrogen oxides emissions from all anthropogenic sources in an 
O3 nonattainment area during the calendar year 1990 (net of 
growth and adjusted pursuant to section 182(b)(1)(B) of the Act), 
expressed as typical O3 season, weekday emissions.
    Rule compliance factor means a factor applied to discount the amount 
of emissions reductions credited in an implementation plan demonstration 
to account for less-than-complete compliance by the affected sources in 
an EIP.
    Shortfall means the difference between the amount of emissions 
reductions credited in an implementation plan for a particular EIP and 
those that are actually achieved by that EIP,

[[Page 384]]

as determined through an approved reconciliation process.
    State means State, local government, or Indian-governing body.
    State implementation plan (SIP) means a plan developed by an 
authorized governing body, including States, local governments, and 
Indian-governing bodies, in a nonattainment area, as required under 
titles I & II of the Clean Air Act, and approved by the EPA as meeting 
these same requirements.
    Stationary source means any building, structure, facility or 
installation, other than an area or mobile source, which emits or may 
emit any criteria air pollutant or precursor subject to regulation under 
the Act.
    Statutory economic incentive program means any EIP submitted to the 
EPA as an implementation plan revision to comply with sections 
182(g)(3), 182(g)(5), 187(d)(3), or 187(g) of the Act.
    Surplus means, at a minimum, emissions reductions in excess of an 
established program baseline which are not required by SIP requirements 
or State regulations, relied upon in any applicable attainment plan or 
demonstration, or credited in any RFP or milestone demonstration, so as 
to prevent the double-counting of emissions reductions.
    Transportation control measure (TCM) is any measure of the types 
listed in section 108(F) of the Act, or any measure in an applicable 
implementation plan directed toward reducing emissions of air pollutants 
from transportation sources by a reduction in vehicle use or changes in 
traffic conditions.



Sec. 51.492  State program election and submittal.

    (a) Extreme O3 nonattainment areas. (1) A State or 
authorized governing body for any extreme O3 nonattainment 
area shall submit a plan revision to implement an EIP, in accordance 
with the requirements of this part, pursuant to section 182(g)(5) of the 
Act, if:
    (i) A required milestone compliance demonstration is not submitted 
within the required period.
    (ii) The Administrator determines that the area has not met any 
applicable milestone.
    (2) The plan revision in paragraph (a)(1) of this section shall be 
submitted within 9 months after such failure or determination, and shall 
be sufficient, in combination with other elements of the SIP, to achieve 
the next milestone.
    (b) Serious CO nonattainment areas. (1) A State or authorized 
governing body for any serious CO nonattainment area shall submit a plan 
revision to implement an EIP, in accordance with the requirements of 
this part, if:
    (i) A milestone demonstration is not submitted within the required 
period, pursuant to section 187(d) of the Act.
    (ii) The Administrator notifies the State, pursuant to section 
187(d) of the Act, that a milestone has not been met.
    (iii) The Administrator determines, pursuant to section 186(b)(2) of 
the Act that the NAAQS for CO has not been attained by the applicable 
date for that area. Such revision shall be submitted within 9 months 
after such failure or determination.
    (2) Submittals made pursuant to paragraphs (b)(1) (i) and (ii) of 
this section shall be sufficient, together with a transportation control 
program, to achieve the specific annual reductions in CO emissions set 
forth in the implementation plan by the attainment date. Submittals made 
pursuant to paragraph (b)(1)(iii) of this section shall be adequate, in 
combination with other elements of the revised plan, to reduce the total 
tonnage of emissions of CO in the area by at least 5 percent per year in 
each year after approval of the plan revision and before attainment of 
the NAAQS for CO.
    (c) Serious and severe O3 nonattainment areas. If a 
State, for any serious or severe O3 nonattainment area, 
elects to implement an EIP in the circumstances set out in section 
182(g)(3) of the Act, the State shall submit a plan revision to 
implement the program in accordance with the requirements of this part. 
If the option to implement an EIP is elected, a plan revision shall be 
submitted within 12 months after the date required for election, and 
shall be sufficient, in combination with other elements of the SIP, to 
achieve the next milestone.

[[Page 385]]

    (d) Any nonattainment or attainment area. Any State may at any time 
submit a plan or plan revision to implement a discretionary EIP, in 
accordance with the requirements of this part, pursuant to sections 
110(a)(2)(A) and 172(c)(6) and other applicable provisions of the Act 
concerning SIP submittals. The plan revision shall not interfere with 
any applicable requirement concerning attainment and RFP, or any other 
applicable requirements of the Act.



Sec. 51.493  State program requirements.

    Economic incentive programs shall be State and federally 
enforceable, nondiscriminatory, and consistent with the timely 
attainment of NAAQS, all applicable RFP and visibility requirements, 
applicable PSD increments, and all other applicable requirements of the 
Act. Programs in nonattainment areas for which credit is taken in 
attainment and RFP demonstrations shall be designed to ensure that the 
effects of the program are quantifiable and permanent over the entire 
duration of the program, and that the credit taken is limited to that 
which is surplus. Statutory programs shall be designed to result in 
quantifiable, significant reductions in actual emissions. The EIP's 
shall include the following elements, as applicable:
    (a) Statement of goals and rationale. This element shall include a 
clear statement as to the environmental problem being addressed, the 
intended environmental and economic goals of the program, and the 
rationale relating the incentive-based strategy to the program goals.
    (1) The statement of goals must include the goal that the program 
will benefit both the environment and the regulated entities. The 
program shall be designed so as to meaningfully meet this goal either 
directly, through increased or more rapid emissions reductions beyond 
those that would be achieved through a traditional regulatory program, 
or, alternatively, through other approaches that will result in real 
environmental benefits. Such alternative approaches include, but are not 
limited to, improved administrative mechanisms, reduced administrative 
burdens on regulatory agencies, improved emissions inventories, and the 
adoption of emission caps which over time constrain or reduce growth-
related emissions beyond traditional regulatory approaches.
    (2) The incentive-based strategy shall be described in terms of one 
of the following three strategies:
    (i) Emission-limiting strategies, which directly specify limits on 
total mass emissions, emission-related parameters (e.g., emission rates 
per unit of production, product content limits), or levels of emissions 
reductions relative to a program baseline that affected sources are 
required to meet, while providing flexibility to sources to reduce the 
cost of meeting program requirements.
    (ii) Market-response strategies, which create one or more incentives 
for affected sources to reduce emissions, without directly specifying 
limits on emissions or emission-related parameters that individual 
sources or even all sources in the aggregate are required to meet.
    (iii) Directionally-sound strategies, for which adequate procedures 
to quantify emissions reductions are not defined.
    (b) Program scope. (1) This element shall contain a clear definition 
of the sources affected by the program. This definition shall address:
    (i) The extent to which the program is mandatory or voluntary for 
the affected sources.
    (ii) Provisions, if any, by which sources that are not required to 
be in the program may voluntarily enter the program.
    (iii) Provisions, if any, by which sources covered by the program 
may voluntarily leave the program.
    (2) Any opt-in or opt-out provisions in paragraph (b)(1) of this 
section shall be designed to provide mechanisms by which such program 
changes are reflected in an area's attainment and RFP demonstrations, 
thus ensuring that there will not be an increase in the emissions 
inventory for the area caused by voluntary entry or exit from the 
program.
    (3) The program scope shall be defined so as not to interfere with 
any other Federal requirements which apply to the affected sources.

[[Page 386]]

    (c) Program baseline. A program baseline shall be defined as a basis 
for projecting program results and, if applicable, for initializing the 
incentive mechanism (e.g., for marketable permits programs). The program 
baseline shall be consistent with, and adequately reflected in, the 
assumptions and inputs used to develop an area's RFP plans and 
attainment and maintenance demonstrations, as applicable. The State 
shall provide sufficient supporting information from the areawide 
emissions inventory and other sources to justify the baseline used in 
the EIP.
    (1) For EIP's submitted in conjunction with, or subsequent to, the 
submission of any areawide progress plan due at the time of EIP 
submission (e.g., the 15 percent RFP plan and/or subsequent 3 percent 
plans) or an attainment demonstration, a State may exercise flexibility 
in setting a program baseline provided the program baseline is 
consistent with and reflected in all relevant progress plans or 
attainment demonstration. A flexible program baseline may be based on 
the lower of actual, allowable, or some other intermediate or lower 
level of emissions. For any EIP submitted prior to the submittal of an 
attainment demonstration, the State shall include the following with its 
EIP submittal:
    (i) A commitment that its subsequent attainment demonstration and 
all future progress plans, if applicable, will be consistent with the 
EIP baseline.
    (ii) A discussion of how the baseline will be integrated into the 
subsequent attainment demonstration, taking into account the potential 
that credit issued prior to the attainment demonstration may no longer 
be surplus relative to the attainment demonstration.
    (2) Except as provided for in paragraph (c)(4) of this section, for 
EIP's submitted during a time period when any progress plans are 
required but not yet submitted (e.g., the 15 percent RFP plan and/or the 
subsequent 3 percent plans), the program baseline shall be based on the 
lower-of-actual-or-allowable emissions. In such cases, actual emissions 
shall be taken from the most appropriate inventory, such as the 1990 
actual emission inventory (due for submission in November 1992), and 
allowable emissions are the lower of SIP-allowable emissions or the 
level of emissions consistent with source compliance with all Federal 
requirements related to attainment and maintenance of the NAAQS.
    (3) For EIP's that are designed to implement new and/or previously 
existing RACT requirements through emissions trading and are submitted 
in conjunction with, or subsequent to, the submission of an associated 
RACT rule, a State may exercise flexibility in setting a program 
baseline provided the program baseline is consistent with and reflected 
in the associated RACT rule, and any applicable progress plans and 
attainment demonstrations.
    (4) For EIP's that are designed to implement new and/or previously 
existing RACT requirements through emissions trading and are submitted 
prior to the submission of a required RFP plan or attainment 
demonstration, States also have flexibility in determining the program 
baseline, provided the following conditions are met.
    (i) For EIP's that implement new RACT requirements for previously 
unregulated source categories through emissions trading, the new RACT 
requirements must reflect, to the extent practicable, increased 
emissions reductions beyond those that would be achieved through a 
traditional RACT program.
    (ii) For EIP's that impose new RACT requirements on previously 
unregulated sources in a previously regulated source category (e.g., 
RACT ``catch-up'' programs), the new incentive-based RACT rule shall, in 
the aggregate, yield reductions in actual emissions at least equivalent 
to that which would result from source-by-source compliance with the 
existing RACT limit for that source category.
    (5) A program baseline for individual sources shall, as appropriate, 
be contained or incorporated by reference in federally-enforceable 
operating permits or a federally-enforceable SIP.
    (6) An initial baseline for TCM's shall be calculated by 
establishing the preexisting conditions in the areas of interest. This 
may include establishing to what extent TCM's have already

[[Page 387]]

been implemented, what average vehicle occupancy (AVO) levels have been 
achieved during peak and off-peak periods, what types of trips occur in 
the region, and what mode choices have been made in making these trips. 
In addition, the extent to which travel options are currently available 
within the region of interest shall be determined. These travel options 
may include, but are not limited to, the degree of dispersion of transit 
services, the current ridership rates, and the availability and usage of 
parking facilities.
    (7) Information used in setting a program baseline shall be of 
sufficient quality to provide for at least as high a degree of 
accountability as currently exists for traditional control requirements 
for the categories of sources affected by the program.
    (d) Replicable emission quantification methods. This program 
element, for programs other than those which are categorized as 
directionally-sound, shall include credible, workable, and replicable 
methods for projecting program results from affected sources and, where 
necessary, for quantifying emissions from individual sources subject to 
the EIP. Such methods, if used to determine credit taken in attainment, 
RFP, and maintenance demonstrations, as applicable, shall yield results 
which can be shown to have a level of certainty comparable to that for 
source-specific standards and traditional methods of control strategy 
development. Such methods include, as applicable, the following 
elements:
    (1) Specification of quantification methods. This element shall 
specify the approach or the combination or range of approaches that are 
acceptable for each source category affected by the program. Acceptable 
approaches may include, but are not limited to:
    (i) Test methods for the direct measurement of emissions, either 
continuously or periodically.
    (ii) Calculation equations which are a function of process or 
control system parameters, ambient conditions, activity levels, and/or 
throughput or production rates.
    (iii) Mass balance calculations which are a function of inventory, 
usage, and/or disposal records.
    (iv) EPA-approved emission factors, where appropriate and adequate.
    (v) Any combination of these approaches.
    (2) Specification of averaging times.
    (i) The averaging time for any specified mass emissions caps or 
emission rate limits shall be consistent with: attaining and maintaining 
all applicable NAAQS, meeting RFP requirements, and ensuring equivalency 
with all applicable RACT requirements.
    (ii) If the averaging time for any specified VOC or NOX 
mass emissions caps or emission rate limits for stationary sources (and 
for other sources, as appropriate) is longer than 24 hours, the State 
shall provide, in support of the SIP submittal, a statistical showing 
that the specified averaging time is consistent with attaining the 
O3 NAAQS and satisfying RFP requirements, as applicable, on 
the basis of typical summer day emissions; and, if applicable, a 
statistical showing that the longer averaging time will produce 
emissions reductions that are equivalent on a daily basis to source-
specific RACT requirements.
    (3) Accounting for shutdowns and production curtailments. This 
accounting shall include provisions which ensure that:
    (i) Emissions reductions associated with shutdowns and production 
curtailments are not double-counted in attainment or RFP demonstrations.
    (ii) Any resultant ``shifting demand'' which increases emissions 
from other sources is accounted for in such demonstrations.
    (4) Accounting for batch, seasonal, and cyclical operations. This 
accounting shall include provisions which ensure that the approaches 
used to account for such variable operations are consistent with 
attainment and RFP plans.
    (5) Accounting for travel mode choice options, as appropriate, for 
TCM's. This accounting shall consider the factors or attributes of the 
different forms of travel modes (e.g., bus, ridesharing) which determine 
which type of travel an individual will choose. Such factors include, 
but are not limited to, time, cost, reliability, and convenience of the 
mode.

[[Page 388]]

    (e) Source requirements. This program element shall include all 
source-specific requirements that constitute compliance with the 
program. Such requirements shall be appropriate, readily ascertainable, 
and State and federally enforceable, including, as applicable:
    (1) Emission limits.
    (i) For programs that impose limits on total mass emissions, 
emission rates, or other emission-related parameter(s), there must be an 
appropriate tracking system so that a facility's limits are readily 
ascertainable at all times.
    (ii) For emission-limiting EIP's that authorize RACT sources to meet 
their RACT requirements through RACT/non-RACT trading, such trading 
shall result in an exceptional environmental benefit. Demonstration of 
an exceptional environmental benefit shall require either the use of the 
statutory offset ratios for nonattainment areas as the determinant of 
the amount of emissions reductions that would be required from non-RACT 
sources generating credits for RACT sources or, alternatively, a trading 
ratio of 1.1 to 1, at a minimum, may be authorized, provided exceptional 
environmental benefits are otherwise demonstrated.
    (2) Monitoring, recordkeeping, and reporting requirements.
    (i) An EIP (or the SIP as a whole) must contain test methods and, 
where necessary, emission quantification methodologies, appropriate to 
the emission limits established in the SIP. EIP sources must be subject 
to clearly specified MRR requirements appropriate to the test methods 
and any applicable quantification methodologies, and consistent with the 
EPA's title V rules, where applicable. Such MRR requirements shall 
provide sufficiently reliable and timely information to determine 
compliance with emission limits and other applicable strategy-specific 
requirements, and to provide for State and Federal enforceability of 
such limits and requirements. Methods for MRR may include, but are not 
limited to:
    (A) The continuous monitoring of mass emissions, emission rates, or 
process or control parameters.
    (B) In situ or portable measurement devices to verify control system 
operating conditions.
    (C) Periodic measurement of mass emissions or emission rates using 
reference test methods.
    (D) Operation and maintenance procedures and/or other work practices 
designed to prevent, identify, or remedy noncomplying conditions.
    (E) Manual or automated recordkeeping of material usage, 
inventories, throughput, production, or levels of required activities.
    (F) Any combination of these methods. EIP's shall require that 
responsible parties at each facility in the EIP program certify reported 
information.
    (ii) Procedures for determining required data, including the 
emissions contribution from affected sources, for periods for which 
required data monitoring is not performed, data are otherwise missing, 
or data have been demonstrated to have been inaccurately determined.
    (3) Any other applicable strategy-specific requirements.
    (f) Projected results and audit/reconciliation procedures. (1) The 
SIP submittal shall include projections of the emissions reductions 
associated with the implementation of the program. These projected 
results shall be related to and consistent with the assumptions used to 
develop the area's attainment demonstration and maintenance plan, as 
applicable. For programs designed to produce emissions reductions 
creditable towards RFP milestones, projected emissions reductions shall 
be related to the RFP baseline and consistent with the area's RFP 
compliance demonstration. The State shall provide sufficient supporting 
information that shows how affected sources are or will be addressed in 
the emissions inventory, RFP plan, and attainment demonstration or 
maintenance plan, as applicable.
    (i) For emission-limiting programs, the projected results shall be 
consistent with the reductions in mass emissions or emissions-related 
parameters specified in the program design.
    (ii) For market-response programs, the projected results shall be 
based on

[[Page 389]]

market analyses relating levels of targeted emissions and/or emission-
related activities to program design parameters.
    (iii) For directionally-sound programs, the projected results may be 
descriptive and shall be consistent with the area's attainment 
demonstration or maintenance plan.
    (2) Quantitative projected results shall be adjusted through the use 
of two uncertainty factors, as appropriate, to reflect uncertainties 
inherent in both the extent to which sources will comply with program 
requirements and the overall program design.
    (i) Uncertainty resulting from incomplete compliance shall be 
addressed through the use of a rule compliance factor.
    (ii) Programmatic uncertainty shall be addressed through the use of 
a program uncertainty factor. Any presumptive norms set by the EPA shall 
be used unless an adequate justification for an alternative factor is 
included in supporting information to be supplied with the SIP 
submittal. In the absence of any EPA-specified presumptive norms, the 
State shall provide an adequate justification for the selected factors 
as part of the supporting information to be supplied with the SIP 
submittal.
    (3) Unless otherwise provided in program-specific guidance issued by 
the EPA, EIP's for which SIP credit is taken shall include audit 
procedures to evaluate program implementation and track program results 
in terms of both actual emissions reductions, and, to the extent 
practicable, cost savings relative to traditional regulatory program 
requirements realized during program implementation. Such audits shall 
be conducted at specified time intervals, not to exceed three years. The 
State shall provide timely post-audit reports to the EPA.
    (i) For emission-limiting EIP's, the State shall commit to ensure 
the timely implementation of programmatic revisions or other measures 
which the State, in response to the audit, deems necessary for the 
successful operation of the program in the context of overall RFP and 
attainment requirements.
    (ii) For market-response EIP's, reconciliation procedures that 
identify a range of appropriate actions or revisions to program 
requirements that will make up for any shortfall between credited 
results (i.e., projected results, as adjusted by the two uncertainty 
factors described above) and actual results obtained during program 
implementation shall be submitted together with the program audit 
provisions. Such measures must be federally enforceable, as appropriate, 
and automatically executing to the extent necessary to make up the 
shortfall within a specified period of time, consistent with relevant 
RFP and attainment requirements.
    (g) Implementation schedule. The program shall contain a schedule 
for the adoption and implementation of all State commitments and source 
requirements included in the program design.
    (h) Administrative procedures. The program shall contain a 
description of State commitments which are integral to the 
implementation of the program, and the administrative system to be used 
to implement the program, addressing the adequacy of the personnel, 
funding, and legislative authority.
    (1) States shall furnish adequate documentation of existing legal 
authority and demonstrated administrative capacity to implement and 
enforce the provisions of the EIP.
    (2) For programs which require private and/or public entities to 
establish emission-related economic incentives (e.g., programs requiring 
employers to exempt carpoolers/multiple occupancy vehicles from paying 
for parking), States shall furnish adequate documentation of State 
authority and administrative capacity to implement and enforce the 
underlying program.
    (i) Enforcement mechanisms. The program shall contain a compliance 
instrument(s) for all program requirements, which is legally binding and 
State and federally enforceable. This program element shall also include 
a State enforcement program which defines violations, and specifies 
auditing and inspections plans and provisions for enforcement actions. 
The program shall contain effective penalties for noncompliance which 
preserve the

[[Page 390]]

level of deterrence in traditional programs. For all such programs, the 
manner of collection of penalties must be specified.
    (1) Emission limit violations. (i) Programs imposing limits on mass 
emissions or emission rates that provide for extended averaging times 
and/or compliance on a multisource basis shall include procedures for 
determining the number of violations, the number of days of violation, 
and sources in violation, for statutory maximum penalty purposes, when 
the limits are exceeded. The State shall demonstrate that such 
procedures shall not lessen the incentive for source compliance as 
compared to a program applied on a source-by-source, daily basis.
    (ii) Programs shall require plans for remedying noncompliance at any 
facility that exceeds a multisource emissions limit for a given 
averaging period. These plans shall be enforceable both federally and by 
the State.
    (2) Violations of MRR requirements. The MRR requirements shall apply 
on a daily basis, as appropriate, and violations thereof shall be 
subject to State enforcement sanctions and to the Federal penalty of up 
to $25,000 for each day a violation occurs or continues. In addition, 
where the requisite scienter conditions are met, violations of such 
requirements shall be subject to the Act's criminal penalty sanctions of 
section 113(c)(2), which provides for fines and imprisonment of up to 2 
years.



Sec. 51.494  Use of program revenues.

    Any revenues generated from statutory EIP's shall be used by the 
State for any of the following:
    (a) Providing incentives for achieving emissions reductions.
    (b) Providing assistance for the development of innovative 
technologies for the control of O3 air pollution and for the 
development of lower-polluting solvents and surface coatings. Such 
assistance shall not provide for the payment of more than 75 percent of 
either the costs of any project to develop such a technology or the 
costs of development of a lower-polluting solvent or surface coating.
    (c) Funding the administrative costs of State programs under this 
Act. Not more than 50 percent of such revenues may be used for this 
purpose. The use of any revenues generated from discretionary EIP's 
shall not be constrained by the provisions of this part.



Subpart W_Determining Conformity of General Federal Actions to State or 
                      Federal Implementation Plans

    Source: 58 FR 63247, Nov. 30, 1993, unless otherwise noted.



Sec. 51.850  [Reserved]



Sec. 51.851  State implementation plan (SIP) or Tribal implementation
plan (TIP) revision.

    (a) A State or eligible Tribe (a federally recognized tribal 
government determined to be eligible to submit a TIP under 40 CFR 49.6) 
may submit to the Environmental Protection Agency (EPA) a revision to 
its applicable implementation plan which contains criteria and 
procedures for assessing the conformity of Federal actions to the 
applicable implementation plan, consistent with this section and 40 CFR 
part 93, subpart B.
    (b) Until EPA approves the conformity implementation plan revision 
permitted by this section, Federal agencies shall use the provisions of 
40 CFR part 93, subpart B in addition to any existing applicable State 
or tribal requirements, to demonstrate conformity with the applicable 
SIP or TIP as required by section 176(c) of the CAA (42 U.S.C. 7506).
    (c) Following EPA approval of the State or tribal conformity 
provisions (or a portion thereof) in a revision to the applicable SIP or 
TIP, conformity determinations shall be governed by the approved (or 
approved portion of) State or tribal criteria and procedures. The 
Federal conformity regulations contained in 40 CFR part 93, subpart B 
would apply only for the portion, if any, of the part 93 requirements 
not contained in the State or Tribe conformity provisions approved by 
EPA.
    (d) The State or tribal conformity implementation plan criteria and 
procedures cannot be any less stringent than the requirements in 40 CFR 
part 93, subpart B.

[[Page 391]]

    (e) A State's or Tribe's conformity provisions may contain criteria 
and procedures more stringent than the requirements described in this 
subpart and part 93, subpart B, only if the State's or Tribe's 
conformity provisions apply equally to non-Federal as well as Federal 
entities.
    (f) In its SIP or TIP, the State or Tribe may identify a list of 
Federal actions or type of emissions that it presumes will conform. The 
State or Tribe may place whatever limitations on that list that it deems 
necessary. The State or Tribe must demonstrate that the action will not 
interfere with timely attainment or maintenance of the standard, meeting 
the reasonable further progress milestones or other requirements of the 
Clean Air Act. Federal agencies can rely on the list to determine that 
their emissions conform with the applicable SIP or TIP.
    (g) Any previously applicable SIP or TIP requirements relating to 
conformity remain enforceable until EPA approves the revision to the SIP 
or TIP to specifically remove them.

[75 FR 17272, Apr. 5, 2010]



Sec. Sec. 51.852-51.860  [Reserved]



Subpart X_Provisions for Implementation of 8-hour Ozone National Ambient 
                          Air Quality Standard

    Source: 69 FR 23996, Apr. 30, 2004, unless otherwise noted.



Sec. 51.900  Definitions.

    The following definitions apply for purposes of this subpart. Any 
term not defined herein shall have the meaning as defined in 40 CFR 
51.100.
    (a) 1-hour NAAQS means the 1-hour ozone national ambient air quality 
standards codified at 40 CFR 50.9.
    (b) 8-hour NAAQS means the 8-hour ozone national ambient air quality 
standards codified at 40 CFR 50.10.
    (c) 1-hour ozone design value is the 1-hour ozone concentration 
calculated according to 40 CFR part 50, Appendix H and the 
interpretation methodology issued by the Administrator most recently 
before the date of the enactment of the CAA Amendments of 1990.
    (d) 8-Hour ozone design value is the 8-hour ozone concentration 
calculated according to 40 CFR part 50, appendix I.
    (e) CAA means the Clean Air Act as codified at 42 U.S.C. 7401-7671q 
(2003).
    (f) Applicable requirements means for an area the following 
requirements to the extent such requirements apply or applied to the 
area for the area's classification under section 181(a)(1) of the CAA 
for the 1-hour NAAQS at designation for the 8-hour NAAQS:
    (1) Reasonably available control technology (RACT).
    (2) Inspection and maintenance programs (I/M).
    (3) Major source applicability cut-offs for purposes of RACT.
    (4) Rate of Progress (ROP) reductions.
    (5) Stage II vapor recovery.
    (6) Clean fuels fleet program under section 183(c)(4) of the CAA.
    (7) Clean fuels for boilers under section 182(e)(3) of the CAA.
    (8) Transportation Control Measures (TCMs) during heavy traffic 
hours as provided under section 182(e)(4) of the CAA.
    (9) Enhanced (ambient) monitoring under section 182(c)(1) of the 
CAA.
    (10) Transportation controls under section 182(c)(5) of the CAA.
    (11) Vehicle miles traveled provisions of section 182(d)(1) of the 
CAA.
    (12) NOX requirements under section 182(f) of the CAA.
    (13) Attainment demonstration or an alternative as provided under 
Sec. 51.905(a)(1)(ii).
    (14) Contingency measures required under CAA sections 172(c)(9) and 
182(c)(9) that would be triggered based on a failure to attain the 1-
hour NAAQS by the applicable attainment date or to make reasonable 
further progress toward attainment of the 1-hour NAAQS.
    (g) Attainment year ozone season shall mean the ozone season 
immediately preceding a nonattainment area's attainment date.
    (h) Designation for the 8-hour NAAQS shall mean the effective date 
of the 8-hour designation for an area.
    (i) Higher classification/lower classification. For purposes of 
determining whether a classification is higher or lower, classifications 
are ranked from

[[Page 392]]

lowest to highest as follows: classification under subpart 1 of the CAA; 
marginal; moderate; serious; severe-15; severe-17; and extreme.
    (j) Initially designated means the first designation that becomes 
effective for an area for the 8-hour NAAQS and does not include a 
redesignation to attainment or nonattainment for that standard.
    (k) Maintenance area for the 1-hour NAAQS means an area that was 
designated nonattainment for the 1-hour NAAQS on or after November 15, 
1990 and was redesignated to attainment for the 1-hour NAAQS subject to 
a maintenance plan as required by section 175A of the CAA.
    (l) Nitrogen Oxides (NOX) means the sum of nitric oxide 
and nitrogen dioxide in the flue gas or emission point, collectively 
expressed as nitrogen dioxide.
    (m) NOX SIP Call means the rules codified at 40 CFR 
51.121 and 51.122.
    (n) Ozone season means for each State, the ozone monitoring season 
as defined in 40 CFR Part 58, Appendix D, section 2.5 for that State.
    (o) Ozone transport region means the area established by section 
184(a) of the CAA or any other area established by the Administrator 
pursuant to section 176A of the CAA for purposes of ozone.
    (p) Reasonable further progress (RFP) means for the purposes of the 
8-hour NAAQS, the progress reductions required under section 172(c)(2) 
and section 182(b)(1) and (c)(2)(B) and (c)(2)(C) of the CAA.
    (q) Rate of progress (ROP) means for purposes of the 1-hour NAAQS, 
the progress reductions required under section 172(c)(2) and section 
182(b)(1) and (c)(2)(B) and (c)(2)(C) of the CAA.
    (r) Revocation of the 1-hour NAAQS means the time at which the 1-
hour NAAQS no longer apply to an area pursuant to 40 CFR 50.9(b).
    (s) Subpart 1 (CAA) means subpart 1 of part D of title I of the CAA.
    (t) Subpart 2 (CAA) means subpart 2 of part D of title I of the CAA.
    (u) Attainment Area means, unless otherwise indicated, an area 
designated as either attainment, unclassifiable, or attainment/
unclassifiable.
    (v) Summer day emissions means an average day's emissions for a 
typical summer work weekday. The state will select the particular 
month(s) in summer and the day(s) in the work week to be represented. 
The selection of conditions should be coordinated with the conditions 
assumed in the development of RFP plans, ROP plans and demonstrations, 
and/or emissions budgets for transportation conformity, to allow 
comparability of daily emission estimates.

[69 FR 23996, Apr. 30, 2004, as amended at 70 FR 30604, May 26, 2005; 77 
FR 28441, May 14, 2012; 80 FR 8799, Feb. 19, 2015]



Sec. 51.901  Applicability of part 51.

    The provisions in subparts A through W of part 51 apply to areas for 
purposes of the 8-hour NAAQS to the extent they are not inconsistent 
with the provisions of this subpart.



Sec. 51.902  Which classification and nonattainment area planning
provisions of the CAA shall apply to areas designated nonattainment 
for the 1997 8-hour NAAQS?
          

    (a) An area designated nonattainment for the 1997 8-hour NAAQS will 
be classified in accordance with section 181 of the CAA, as interpreted 
in Sec. 51.903(a), for purposes of the 1997 8-hour NAAQS, and will be 
subject to the requirements of subpart 2 that apply for that 
classification.
    (b) [Reserved]

[77 FR 28841, May 14, 2012]



Sec. 51.903  How do the classification and attainment date provisions
in section 181 of subpart 2 of the CAA apply to areas subject to Sec.
51.902(a)?

    (a) In accordance with section 181(a)(1) of the CAA, each area 
subject to Sec. 51.902(a) shall be classified by operation of law at 
the time of designation. However, the classification shall be based on 
the 8-hour design value for the area, in accordance with Table 1 below, 
or such higher or lower classification as the State may request as 
provided in paragraphs (b) and (c) of this section. The 8-hour design 
value for the area shall be calculated using the three most recent years 
of air quality data. For each area classified under this section, the 
primary NAAQS attainment date for the 8-hour NAAQS shall be as 
expeditious as practicable

[[Page 393]]

but not later than the date provided in the following Table 1.

              Table 1--Classification for 8-Hour Ozone NAAQS for Areas Subject to Sec. 51.902(a)
----------------------------------------------------------------------------------------------------------------
                                                                                            Maximum period for
                                                                                           attainment dates in
                                                                          8-hour design     state plans (years
                Area class                                                 value (ppm    after effective date of
                                                                             ozone)           nonattainment
                                                                                          designation for 8-hour
                                                                                                  NAAQS)
----------------------------------------------------------------------------------------------------------------
Marginal.................................  from........................           0.085                        3
                                           up to \1\...................           0.092
Moderate.................................  from........................           0.092                        6
                                           up to \1\...................           0.107
Serious..................................  from........................           0.107                        9
                                           up to \1\...................           0.120
Severe-15................................  from........................           0.120                       15
                                           up to \1\...................           0.127
Severe-17................................  from........................           0.127                       17
                                           up to \1\...................           0.187
Extreme..................................  equal to....................           0.187                      20
                                           or above....................
----------------------------------------------------------------------------------------------------------------
\1\ but not including.

    (b) A State may request a higher classification for any reason in 
accordance with section 181(b)(3) of the CAA.
    (c) A State may request a lower classification in accordance with 
section 181(a)(4) of the CAA.



Sec. 51.904  How do the classification and attainment date provisions
in section 172(a) of subpart 1 of the CAA apply to areas subject to 
Sec. 51.902(b)?

    (a) Classification. The Administrator may classify an area subject 
to Sec. 51.902(b) as an overwhelming transport area if:
    (1) The area meets the criteria as specified for rural transport 
areas under section 182(h) of the CAA;
    (2) Transport of ozone and/or precursors into the area is so 
overwhelming that the contribution of local emissions to observed 8-hour 
ozone concentration above the level of the NAAQS is relatively minor; 
and
    (3) The Administrator finds that sources of VOC (and, where the 
Administrator determines relevant, NOX) emissions within the 
area do not make a significant contribution to the ozone concentrations 
measured in other areas.
    (b) Attainment dates. For an area subject to Sec. 51.902(b), the 
Administrator will approve an attainment date consistent with the 
attainment date timing provision of section 172(a)(2)(A) of the CAA at 
the time the Administrator approves an attainment demonstration for the 
area.



Sec. 51.905  How do areas transition from the 1-hour NAAQS to the 1997
8-hour NAAQS and what are the anti-backsliding provisions?

    (a) What requirements that applied in an area for the 1-hour NAAQS 
continue to apply after revocation of the 1-hour NAAQS for that area?--
(1) 8-Hour NAAQS Nonattainment/1-Hour NAAQS Nonattainment. The following 
requirements apply to an area designated nonattainment for the 8-hour 
NAAQS and designated nonattainment for the 1-hour NAAQS at the time of 
designation for the 8-hour NAAQS for that area.
    (i) The area remains subject to the obligation to adopt and 
implement the applicable requirements as defined in Sec. 51.900(f), 
except as provided in paragraph (a)(1)(iii) of this section, and except 
as provided in paragraph (b) of this section.
    (ii) If the area has not met its obligation to have a fully-approved 
attainment demonstration SIP for the 1-hour NAAQS, the State must comply 
with one of the following:
    (A) Submit a 1-hour attainment demonstration no later than 1 year 
after designation;
    (B) Submit a RFP plan for the 8-hour NAAQS no later than 1-year 
following designations for the 8-hour NAAQS providing a 5 percent 
increment of emissions reduction from the area's

[[Page 394]]

2002 emissions baseline, which must be in addition to measures (or 
enforceable commitments to measures) in the SIP at the time of the 
effective date of designation and in addition to national or regional 
measures and must be achieved no later than 2 years after the required 
date for submission (3 years after designation).
    (C) Submit an 8-hour ozone attainment demonstration no later than 1 
year following designations that demonstrates attainment of the 8-hour 
NAAQS by the area's attainment date; provides for 8-hour RFP for the 
area out to the attainment date; and for the initial period of RFP for 
the area (between 2003-2008), achieve the emission reductions by 
December 31, 2007.
    (iii) If the area has an outstanding obligation for an approved 1-
hour ROP SIP, it must develop and submit to EPA all outstanding 1-hour 
ROP plans; where a 1-hour obligation overlaps with an 8-hour RFP 
requirement, the State's 8-hour RFP plan can be used to satisfy the 1-
hour ROP obligation if the 8-hour RFP plan has an emission target at 
least as stringent as the 1-hour ROP emission target in each of the 1-
hour ROP target years for which the 1-hour ROP obligation exists.
    (2) 8-Hour NAAQS Nonattainment/1-Hour NAAQS Maintenance. An area 
designated nonattainment for the 8-hour NAAQS that is a maintenance area 
for the 1-hour NAAQS at the time of designation for the 8-hour NAAQS for 
that area remains subject to the obligation to implement the applicable 
requirements as defined in Sec. 51.900 (f) to the extent such 
obligations are required by the approved SIP, except as provided in 
paragraph (b) of this section. Applicable measures in the SIP must 
continue to be implemented; however, if these measures were shifted to 
contingency measures prior to designation for the 8-hour NAAQS for the 
area, they may remain as contingency measures, unless the measures are 
required to be implemented by the CAA by virtue of the area's 
requirements under the 8-hour NAAQS. The State may not remove such 
measures from the SIP.
    (3) 8-Hour NAAQS Attainment/1-Hour NAAQS Nonattainment--(i) 
Obligations in an approved SIP. For an area that is 8-hour NAAQS 
attainment/1-hour NAAQS nonattainment, the State may request that 
obligations under the applicable requirements of Sec. 51.900(f) be 
shifted to contingency measures, consistent with sections 110(l) and 193 
of the CAA, after revocation of the 1-hour NAAQS; however, the State 
cannot remove the obligations from the SIP. For such areas, the State 
may request that the nonattainment NSR provisions be removed from the 
SIP on or after the date of revocation of the 1-hour NAAQS and need not 
be shifted to contingency measures subject to paragraph (e)(4) of this 
section.
    (ii) Attainment demonstration and ROP plans. (A) To the extent an 8-
hour NAAQS attainment/1-hour NAAQS nonattainment area does not have an 
approved attainment demonstration or ROP plan that was required for the 
1-hour NAAQS under the CAA, the obligation to submit such an attainment 
demonstration or ROP plan
    (1) Is deferred for so long as the area continues to maintain the 8-
hour NAAQS; and
    (2) No longer applies once the area has an approved maintenance plan 
pursuant to paragraph (a)(3)(iii) of this section.
    (B) For an 8-hour NAAQS attainment/1-hour NAAQS nonattainment area 
that violates the 8-hour NAAQS, prior to having an approved maintenance 
plan for the 8-hour NAAQS as provided under paragraph (a)(3)(iii) of 
this section, paragraphs (a)(3)(ii)(B)(1), (2), and (3) of this section 
shall apply.
    (1) In lieu of any outstanding obligation to submit an attainment 
demonstration, within 1 year after the date on which EPA publishes a 
determination that a violation of the 8-hour NAAQS has occurred, the 
State must submit (or revise a submitted) maintenance plan for the 8-
hour NAAQS, as provided under paragraph (a)(3)(iii) of this section, 
to--
    (i) Address the violation by relying on modeling that meets EPA 
guidance for purposes of demonstrating maintenance of the NAAQS; or
    (ii) Submit a SIP providing for a 3 percent increment of emissions 
reductions from the area's 2002 emissions baseline; these reductions 
must be in addition to measures (or enforceable commitments to measures) 
in the SIP

[[Page 395]]

at the time of the effective date of designation and in addition to 
national or regional measures.
    (2) The plan required under paragraph (a)(3)(ii)(B)(1) of this 
section must provide for the emission reductions required within 3 years 
after the date on which EPA publishes a determination that a violation 
of the 8-hour NAAQS has occurred.
    (3) The State shall submit an ROP plan to achieve any outstanding 
ROP reductions that were required for the area for the 1-hour NAAQS, and 
the 3-year period or periods for achieving the ROP reductions will begin 
January 1 of the year following the 3-year period on which EPA bases its 
determination that a violation of the 8-hour NAAQS occurred.
    (iii) Maintenance plans for the 8-hour NAAQS. For areas initially 
designated attainment for the 8-hour NAAQS, and designated nonattainment 
for the 1-hour NAAQS at the time of designation for the 8-hour NAAQS, 
the State shall submit no later than 3 years after the area's 
designation for the 8-hour NAAQS, a maintenance plan for the 8-hour 
NAAQS in accordance with section 110(a)(1) of the CAA. The maintenance 
plan must provide for continued maintenance of the 8-hour NAAQS for 10 
years following designation and must include contingency measures. This 
provision does not apply to areas redesignated from nonattainment to 
attainment for the 8-hour NAAQS pursuant to CAA section 107(d)(3); such 
areas are subject to the maintenance plan requirement in section 175A of 
the CAA.
    (4) 8-Hour NAAQS Attainment/1-Hour NAAQS Maintenance--(i) 
Obligations in an approved SIP. For an 8-hour NAAQS attainment/1-hour 
NAAQS maintenance area, the State may request that obligations under the 
applicable requirements of Sec. 51.900(f) be shifted to contingency 
measures, consistent with sections 110(l) and 193 of the CAA, after 
revocation of the 1-hour NAAQS; however, the State cannot remove the 
obligations from the SIP.
    (ii) Maintenance Plans for the 8-hour NAAQS. For areas initially 
designated attainment for the 8-hour NAAQS and subject to the 
maintenance plan for the 1-hour NAAQS at the time of designation for the 
8-hour NAAQS, the State shall submit no later than 3 years after the 
area's designation for the 8-hour NAAQS, a maintenance plan for the 8-
hour NAAQS in accordance with section 110(a)(1) of the CAA. The 
maintenance plan must provide for continued maintenance of the 8-hour 
NAAQS for 10 years following designation and must include contingency 
measures. This provision does not apply to areas redesignated from 
nonattainment to attainment for the 8-hour NAAQS pursuant to section 
107(d)(3); such areas are subject to the maintenance plan requirement in 
section 175A of the CAA.
    (b) Does attainment of the ozone NAAQS affect the obligations under 
paragraph (a) of this section? A State remains subject to the 
obligations under paragraphs (a)(1)(i) and (a)(2) of this section until 
the area attains the 8-hour NAAQS. After the area attains the 8-hour 
NAAQS, the State may request such obligations be shifted to contingency 
measures, consistent with sections 110(l) and 193 of the CAA; however, 
the State cannot remove the obligations from the SIP. Once an area 
attains the 1-hour NAAQS, the section 172 and 182 contingency measures 
under the 1-hour NAAQS can be shifted to contingency measures for the 
1997 8-hour ozone NAAQS and must remain in the SIP until the area is 
redesignated to attainment for the 1997 8-hour NAAQS.
    (c) Which portions of an area designated for the 8-hour NAAQS remain 
subject to the obligations identified in paragraph (a) of this section? 
(1) Except as provided in paragraph (c)(2) of this section, only the 
portion of the designated area for the 8-hour NAAQS that was required to 
adopt the applicable requirements in Sec. 51.900(f) for purposes of the 
1-hour NAAQS is subject to the obligations identified in paragraph (a) 
of this section, including the requirement to submit a maintenance plan 
for purposes of paragraph (a)(3)(iii) of this section. 40 CFR part 81, 
subpart C identifies the boundaries of areas and the area designations 
and classifications for the 1-hour NAAQS in place as of the effective 
date of designation for the 8-hour NAAQS.
    (2) For purposes of paragraph (a)(1)(ii)(B) and (C) of this section, 
the

[[Page 396]]

requirement to achieve emission reductions applies to the entire area 
designated nonattainment for the 8-hour ozone NAAQS.
    (d) [Reserved]
    (e) What obligations that applied for the 1-hour NAAQS will no 
longer apply after revocation of the 1-hour NAAQS for an area?--(1) 
Maintenance plans. Upon revocation of the 1-hour NAAQS, an area with an 
approved 1-hour maintenance plan under section 175A of the CAA may 
modify the maintenance plan: To remove the obligation to submit a 
maintenance plan for the 1-hour NAAQS 8 years after approval of the 
initial 1-hour maintenance plan; and to remove the obligation to 
implement contingency measures upon a violation of the 1-hour NAAQS. 
However, such requirements will remain enforceable as part of the 
approved SIP until such time as EPA approves a SIP revision removing 
such obligations. The EPA shall not approve a SIP revision requesting 
these modifications until the State submits and EPA approves an 
attainment demonstration for the 8-hour NAAQS for an area initially 
designated nonattainment for the 8-hour ozone NAAQS or a maintenance SIP 
for the 8-hour NAAQS for an area initially designated attainment for the 
8-hour NAAQS. Any revision to such SIP must meet the requirements of 
section 110(l) and 193 of the CAA.
    (2) Findings of failure to attain the 1-hour NAAQS. (i) Upon 
revocation of the 1-hour NAAQS for an area, EPA is no longer obligated--
    (A) To determine pursuant to section 181(b)(2) or section 179(c) of 
the CAA whether an area attained the 1-hour NAAQS by that area's 
attainment date for the 1-hour NAAQS; or
    (B) To reclassify an area to a higher classification for the 1-hour 
NAAQS based upon a determination that the area failed to attain the 1-
hour NAAQS by the area's attainment date for the 1-hour NAAQS.
    (ii)-(iii) [Reserved]
    (3) Conformity determinations for the 1-hour NAAQS. Upon revocation 
of the 1-hour NAAQS for an area, conformity determinations pursuant to 
section 176(c) of the CAA are no longer required for the 1-hour NAAQS. 
At that time, any provisions of applicable SIPs that require conformity 
determinations in such areas for the 1-hour NAAQS will no longer be 
enforceable pursuant to section 176(c)(5) of the CAA.
    (f) What is the continued applicability of the NOX SIP 
Call after revocation of the 1-hour NAAQS? The NOX SIP Call 
shall continue to apply after revocation of the 1-hour NAAQS. Control 
obligations approved into the SIP pursuant to 40 CFR 51.121 and 51.122 
may be modified by the State only if the requirements of Sec. Sec. 
51.121 and 51.122, including the statewide NOX emission 
budgets, continue to be met and the State makes a showing consistent 
with section 110(l) of the CAA.

[69 FR 23996, Apr. 30, 2004, as amended at 70 FR 30604, May 26, 2005; 70 
FR 44474, Aug. 3, 2005; 77 FR 28441, May 14, 2012]



Sec. 51.906  Redesignation to nonattainment following initial
designations for the 8-hour NAAQS.

    For any area that is initially designated attainment or 
unclassifiable for the 8-hour NAAQS and that is subsequently 
redesignated to nonattainment for the 8-hour ozone NAAQS, any absolute, 
fixed date applicable in connection with the requirements of this part 
is extended by a period of time equal to the length of time between the 
effective date of the initial designation for the 8-hour NAAQS and the 
effective date of redesignation, except as otherwise provided in this 
subpart.

[70 FR 71700, Nov. 29, 2005]



Sec. 51.907  For an area that fails to attain the 8-hour NAAQS by its 
attainment date, how does EPA interpret sections 172(a)(2)(C)(ii) and 
181(a)(5)(B) of the CAA?
          

    For purposes of applying sections 172(a)(2)(C) and 181(a)(5) of the 
CAA, an area will meet the requirement of section 172(a)(2)(C)(ii) or 
181(a)(5)(B) of the CAA pertaining to 1-year extensions of the 
attainment date if:
    (a) For the first 1-year extension, the area's 4th highest daily 8-
hour average in the attainment year is 0.084 ppm or less.
    (b) For the second 1-year extension, the area's 4th highest daily 8-
hour value, averaged over both the original

[[Page 397]]

attainment year and the first extension year, is 0.084 ppm or less.
    (c) For purposes of paragraphs (a) and (b) of this section, the 
area's 4th highest daily 8-hour average shall be from the monitor with 
the highest 4th highest daily 8-hour average of all the monitors that 
represent that area.



Sec. 51.908  What modeling and attainment demonstration requirements
apply for purposes of the 8-hour ozone NAAQS?

    (a) What is the attainment demonstration requirement for an area 
classified as moderate or higher under subpart 2 pursuant to Sec. 
51.903? An area classified as moderate or higher under Sec. 51.903 
shall be subject to the attainment demonstration requirement applicable 
for that classification under section 182 of the Act, except such 
demonstration is due no later than 3 years after the area's designation 
for the 8-hour NAAQS.
    (b) What is the attainment demonstration requirement for an area 
subject only to subpart 1 in accordance with Sec. 51.902(b)? An area 
subject to Sec. 51.902(b) shall be subject to the attainment 
demonstration under section 172(c)(1) of the Act and shall submit an 
attainment demonstration no later than 3 years after the area's 
designation for the 8-hour NAAQS.
    (c) What criteria must the attainment demonstration meet? An 
attainment demonstration due pursuant to paragraph (a) or (b) of this 
section must meet the requirements of Sec. 51.112; the adequacy of an 
attainment demonstration shall be demonstrated by means of a 
photochemical grid model or any other analytical method determined by 
the Administrator, in the Administrator's discretion, to be at least as 
effective.
    (d) For each nonattainment area, the State must provide for 
implementation of all control measures needed for attainment no later 
than the beginning of the attainment year ozone season.

[69 FR 23996, Apr. 30, 2004, as amended at 70 FR 71700, Nov. 29, 2005]



Sec. 51.909  [Reserved]



Sec. 51.910  What requirements for reasonable further progress (RFP)
under sections 172(c)(2) and 182 apply for areas designated
nonattainment for the 8-hour ozone NAAQS?
          

    (a) What are the general requirements for RFP for an area classified 
under subpart 2 pursuant to Sec. 51.903? For an area classified under 
subpart 2 pursuant to Sec. 51.903, the RFP requirements specified in 
section 182 of the Act for that area's classification shall apply.
    (1) What is the content and timing of the RFP plan required under 
sections 182(b)(1) and 182(c)(2)(B) of the Act for an area classified as 
moderate or higher pursuant to Sec. 51.903 (subpart 2 coverage)?
    (i) Moderate or Above Area. (A) Except as provided in paragraph 
(a)(1)(ii) of this section, for each area classified as moderate or 
higher, the State shall submit a SIP revision consistent with section 
182(b)(1) of the Act no later than 3 years after designation for the 8-
hour NAAQS for the area. The 6-year period referenced in section 
182(b)(1) of the Act shall begin January 1 of the year following the 
year used for the baseline emissions inventory.
    (B) For each area classified as serious or higher, the State shall 
submit a SIP revision consistent with section 182(c)(2)(B) of the Act no 
later than 3 years after designation for the 8-hour NAAQS. The final 
increment of progress must be achieved no later than the attainment date 
for the area.
    (ii) Area with Approved 1-hour Ozone 15 Percent VOC ROP Plan. An 
area classified as moderate or higher that has the same boundaries as an 
area, or is entirely composed of several areas or portions of areas, for 
which EPA fully approved a 15 percent plan for the 1-hour NAAQS is 
considered to have met section 182(b)(1) of the Act for the 8-hour NAAQS 
and instead:
    (A) If classified as moderate, the area is subject to RFP under 
section 172(c)(2) of the Act and shall submit no later than 3 years 
after designation for the 8-hour NAAQS a SIP revision that meets the 
requirements of paragraph (b)(2) of this section, consistent with the 
attainment date established in the attainment demonstration SIP.

[[Page 398]]

    (B) If classified as serious or higher, the area is subject to RFP 
under section 182(c)(2)(B) of the Act and shall submit no later than 3 
years after designation for the 8-hour NAAQS an RFP SIP providing for an 
average of 3 percent per year of VOC and/or NOX emissions 
reductions for
    (1) the 6-year period beginning January 1 of the year following the 
year used for the baseline emissions inventory; and
    (2) all remaining 3-year periods after the first 6-year period out 
to the area's attainment date.
    (iii) Moderate and Above Area for Which Only a Portion Has an 
Approved 1-hour Ozone 15 Percent VOC ROP Plan. An area classified as 
moderate or higher that contains one or more areas, or portions of 
areas, for which EPA fully approved a 15 percent plan for the 1-hour 
NAAQS as well as areas for which EPA has not fully approved a 15 percent 
plan for the 1-hour NAAQS shall meet the requirements of either 
paragraph (a)(1)(iii)(A) or (B) below.
    (A) The State shall not distinguish between the portion of the area 
that previously met the 15 percent VOC reduction requirement and the 
portion of the area that did not, and
    (1) The State shall submit a SIP revision consistent with section 
182(b)(1) of the Act no later than 3 years after designation for the 8-
hour NAAQS for the entire area. The 6-year period referenced in section 
182(b)(1) of the Act shall begin January 1 of the year following the 
year used for the baseline emissions inventory.
    (2) For each area classified as serious or higher, the State shall 
submit a SIP revision consistent with section 182(c)(2)(B) of the Act no 
later than 3 years after designation for the 8-hour NAAQS. The final 
increment of progress must be achieved no later than the attainment date 
for the area.
    (B) The State shall treat the area as two parts, each with a 
separate RFP target as follows:
    (1) For the portion of the area without an approved 15 percent VOC 
RFP plan for the 1-hour standard, the State shall submit a SIP revision 
consistent with section 182(b)(1) of the Act no later than 3 years after 
designation for the 8-hour NAAQS for the area. The 6-year period 
referenced in section 182(b)(1) of the Act shall begin January 1 of the 
year following the year used for the baseline emissions inventory. 
Emissions reductions to meet this requirement may come from anywhere 
within the 8-hour nonattainment area.
    (2) For the portion of the area with an approved 15 percent VOC plan 
for the 1-hour NAAQS, the State shall submit a SIP as required under 
paragraph (b)(2)of this section.
    (2) What restrictions apply on the creditability of emission control 
measures for the RFP plans required under this section? Except as 
specifically provided in section 182(b)(1)(C) and (D) and section 
182(c)(2)(B) of the Act, all SIP-approved or federally promulgated 
emissions reductions that occur after the baseline emissions inventory 
year are creditable for purposes of the RFP requirements in this 
section, provided the reductions meet the requirements for 
creditability, including the need to be enforceable, permanent, 
quantifiable and surplus, as described for purposes of State economic 
incentive programs in the requirements of Sec. 51.493 of this part.
    (b) How does the RFP requirement of section 172(c)(2) of the Act 
apply to areas subject to that requirement? (1) An area subject to the 
RFP requirement of subpart 1 pursuant to Sec. 51.902(b) or a moderate 
area subject to subpart 2 as covered in paragraphs (a)(1)(ii)(A) of this 
section shall meet the RFP requirements of section 172(c)(2) of the Act 
as provided in paragraph (b)(2) of this section.
    (2) The State shall submit no later than 3 years following 
designation for the 8-hour NAAQS a SIP providing for RFP consistent with 
the following:
    (i) For each area with an attainment demonstration requesting an 
attainment date of 5 years or less after designation for the 8-hour 
NAAQS, the attainment demonstration SIP shall require that all emissions 
reductions needed for attainment be implemented by the beginning of the 
attainment year ozone season.
    (ii) For each area with an attainment demonstration requesting an 
attainment date more than 5 years after designation for the 8-hour 
NAAQS, the attainment demonstration SIP--

[[Page 399]]

    (A) Shall provide for a 15 percent emission reduction from the 
baseline year within 6 years after the baseline year.
    (B) May use either NOX or VOC emissions reductions (or 
both) to achieve the 15 percent emission reduction requirement. Use of 
NOX emissions reductions must meet the criteria in section 
182(c)(2)(C) of the Act.
    (C) For each subsequent 3-year period out to the attainment date, 
the RFP SIP must provide for an additional increment of progress. The 
increment for each 3-year period must be a portion of the remaining 
emission reductions needed for attainment beyond those reductions 
achieved for the first increment of progress (e.g., beyond 2008 for 
areas designated nonattainment in June 2004). Specifically, the amount 
of reductions needed for attainment is divided by the number of years 
needed for attainment after the first increment of progress in order to 
establish an ``annual increment.'' For each 3-year period out to the 
attainment date, the area must achieve roughly the portion of reductions 
equivalent to three annual increments.
    (c) What method should a State use to calculate RFP targets? In 
calculating RFP targets for the initial 6-year period and the subsequent 
3-year periods pursuant to this section, the State shall use the methods 
consistent with the requirements of sections 182(b)(1)(C) and (D) and 
182(c)(2)(B) to properly account for non-creditable reductions.
    (d) What is the baseline emissions inventory for RFP plans? For the 
RFP plans required under this section, the baseline emissions inventory 
shall be determined at the time of designation of the area for the 8-
hour NAAQS and shall be the emissions inventory for the most recent 
calendar year for which a complete inventory is required to be submitted 
to EPA under the provisions of subpart A of this part or a more recent 
alternative baseline emissions inventory provided the State demonstrates 
that the baseline inventory meets the CAA provisions for RFP and 
provides a rationale for why it is appropriate to use the alternative 
baseline year rather than 2002 to comply with the CAA's RFP provisions.

[70 FR 71700, Nov. 29, 2005]



Sec. 51.911  [Reserved]



Sec. 51.912  What requirements apply for reasonably available control
technology (RACT) and reasonably available control measures (RACM) 
under the 8-hour NAAQS?
          

    (a) What is the RACT requirement for areas subject to subpart 2 in 
accordance with Sec. 51.903? (1) For each area subject to subpart 2 in 
accordance with Sec. 51.903 of this part and classified moderate or 
higher, the State shall submit a SIP revision that meets the 
NOX and VOC RACT requirements in sections 182(b)(2) and 
182(f) of the Act.
    (2) The State shall submit the RACT SIP for each area no later than 
27 months after designation for the 8-hour ozone NAAQS, except that for 
a State subject to the requirements of the Clean Air Interstate Rule, 
the State shall submit NOX RACT SIPs for electrical 
generating units (EGUs) no later than the date by which the area's 
attainment demonstration is due (prior to any reclassification under 
section 181(b)(3)) for the 8-hour ozone national ambient air quality 
standard, or July 9, 2007, whichever comes later.
    (3) The State shall provide for implementation of RACT as 
expeditiously as practicable but no later than the first ozone season or 
portion thereof which occurs 30 months after the RACT SIP is due.
    (b) How do the RACT provisions apply to a major stationary source? 
Volatile organic compounds and NOX are to be considered 
separately for purposes of determining whether a source is a major 
stationary source as defined in section 302 of the Act.
    (c) What is the RACT requirement for areas subject only to subpart 1 
pursuant to Sec. 51.902(b)? Areas subject only to subpart 1 pursuant to 
Sec. 51.902(b) are subject to the RACT requirement specified in section 
172(c)(1) of the Act.
    (1) For an area that submits an attainment demonstration that 
requests an attainment date 5 years or less after designation for the 8-
hour NAAQS, the State shall meet the RACT requirement by submitting an 
attainment

[[Page 400]]

demonstration SIP demonstrating that the area has adopted all control 
measures necessary to demonstrate attainment as expeditiously as 
practicable.
    (2) For an area that submits an attainment demonstration that 
requests an attainment date more than 5 years after designation for the 
8-hour NAAQS, the State shall submit a SIP consistent with the 
requirements of Sec. 51.912(a) and (b) except the State shall submit 
the RACT SIP for each area with its request pursuant to Clean Air Act 
section 172(a)(2)(A) to extend the attainment date.
    (d) What is the Reasonably Available Control Measures (RACM) 
requirement for areas designated nonattainment for the 8-hour NAAQS? For 
each nonattainment area required to submit an attainment demonstration 
under Sec. 51.908, the State shall submit with the attainment 
demonstration a SIP revision demonstrating that it has adopted all RACM 
necessary to demonstrate attainment as expeditiously as practicable and 
to meet any RFP requirements.

[70 FR 71701, Nov. 29, 2005, as amended at 72 FR 31749, June 8, 2007]



Sec. 51.913  How do the section 182(f) NOX exemption provisions apply
for the 8-hour NAAQS?

    (a) A person may petition the Administrator for an exemption from 
NOX obligations under section 182(f) for any area designated 
nonattainment for the 8-hour ozone NAAQS and for any area in a section 
184 ozone transport region.
    (b) The petition must contain adequate documentation that the 
criteria in section 182(f) are met.
    (c) A section 182(f) NOX exemption granted for the 1-hour 
ozone standard does not relieve the area from any NOX 
obligations under section 182(f) for the 8-hour ozone standard.

[70 FR 71701, Nov. 29, 2005]



Sec. 51.914  What new source review requirements apply for 8-hour
ozone nonattainment areas?

    The requirements for new source review for the 8-hour ozone standard 
are located in Sec. 51.165 of this part.

[70 FR 71702, Nov. 29, 2005]



Sec. 51.915  What emissions inventory requirements apply under the
8-hour NAAQS?

    For each nonattainment area subject to subpart 2 in accordance with 
Sec. 51.903, the emissions inventory requirements in sections 182(a)(1) 
and 182(a)(3) of the Act shall apply, and such SIP shall be due no later 
2 years after designation. For each nonattainment area subject only to 
title I, part D, subpart 1 of the Act in accordance with Sec. 
51.902(b), the emissions inventory requirement in section 172(c)(3) of 
the Act shall apply, and an emission inventory SIP shall be due no later 
3 years after designation. The state must report to the EPA summer day 
emissions of NOX and VOC from all point sources, nonpoint 
sources, onroad mobile sources, and nonroad mobile sources. The state 
shall report emissions as point sources according to the point source 
emissions thresholds of the Air Emissions Reporting Rule (AERR), 40 CFR 
part 51, subpart A. The detail of the emissions inventory shall be 
consistent with the data elements required by 40 CFR part 51, subpart A.

[80 FR 8799, Feb. 19, 2015]



Sec. 51.916  What are the requirements for an Ozone Transport Region
under the 8-hour NAAQS?

    (a) In General. Sections 176A and 184 of the Act apply for purposes 
of the 8-hour NAAQS.
    (b) RACT Requirements for Certain Portions of an Ozone Transport 
Region.
    (1) The State shall submit a SIP revision that meets the RACT 
requirements of section 184 of the Act for each area that is located in 
an ozone transport region and that is--
    (i) Designated as attainment or unclassifiable for the 8-hour 
standard;
    (ii) Designated nonattainment and classified as marginal for the 8-
hour standard; or
    (iii) Designated nonattainment and covered solely under subpart 1 of 
part D, title I of the CAA for the 8-hour standard.
    (2) The State is required to submit the RACT revision no later than 
September 16, 2006 and shall provide for

[[Page 401]]

implementation of RACT as expeditiously as practicable but no later than 
May 1, 2009.

[70 FR 71702, Nov. 29, 2005]



Sec. 51.917  What is the effective date of designation for the 
Las Vegas, NV, 8-hour ozone nonattainment area?

    The Las Vegas, NV, 8-hour ozone nonattainment area (designated on 
September 17, 2004 (69 FR 55956)) shall be treated as having an 
effective date of designation of June 15, 2004, for purposes of 
calculating SIP submission deadlines, attainment dates, or any other 
deadline under this subpart.

[70 FR 71702, Nov. 29, 2005]



Sec. 51.918  Can any SIP planning requirements be suspended in 
8-hour ozone nonattainment areas that have air quality data that 
meets the NAAQS?

    Upon a determination by EPA that an area designated nonattainment 
for the 8-hour ozone NAAQS has attained the standard, the requirements 
for such area to submit attainment demonstrations and associated 
reasonably available control measures, reasonable further progress 
plans, contingency measures, and other planning SIPs related to 
attainment of the 8-hour ozone NAAQS shall be suspended until such time 
as: the area is redesignated to attainment, at which time the 
requirements no longer apply; or EPA determines that the area has 
violated the 8-hour ozone NAAQS.

[70 FR 71702, Nov. 29, 2005]



Sec. 51.919  Applicability.

    As of April 6, 2015, the provisions of subpart AA shall replace the 
provisions of subpart X, Sec. Sec. 51.900 to 51.918, which will cease 
to apply, with the exception of the attainment date extension provisions 
of Sec. 51.907 for the anti-backsliding purposes of Sec. 
51.1105(d)(2).

[80 FR 12312, Mar. 6, 2015]



                    Subpart Y_Mitigation Requirements



Sec. 51.930  Mitigation of Exceptional Events.

    (a) A State requesting to exclude air quality data due to 
exceptional events must take appropriate and reasonable actions to 
protect public health from exceedances or violations of the national 
ambient air quality standards. At a minimum, the State must:
    (1) Provide for prompt public notification whenever air quality 
concentrations exceed or are expected to exceed an applicable ambient 
air quality standard;
    (2) Provide for public education concerning actions that individuals 
may take to reduce exposures to unhealthy levels of air quality during 
and following an exceptional event; and
    (3) Provide for the implementation of appropriate measures to 
protect public health from exceedances or violations of ambient air 
quality standards caused by exceptional events.
    (b) Development of mitigation plans for areas with historically 
documented or known seasonal events--(1) Generally. All States having 
areas with historically documented or known seasonal events shall be 
required to develop a mitigation plan with the components identified in 
paragraph (b)(2) of this section and submit such plan to the 
Administrator according to the requirements in paragraph (b)(3) of this 
section.
    (i) For purposes of the requirements set forth in this section, 
historically documented or known seasonal events shall include those 
events of the same type and pollutant that recur in a 3-year period and 
meet any of the following:
    (A) Three events or event seasons for which a State submits a 
demonstration under the provisions of 40 CFR 50.14 in a 3-year period; 
or
    (B) Three events or event seasons that are the subject of an initial 
notification of a potential exceptional event as defined in 40 CFR 
50.14(c)(2) in a 3-year period regardless of whether the State submits a 
demonstration under the provisions of 40 CFR 50.14.
    (ii) The Administrator will provide written notification to States 
that they are subject to the requirements in

[[Page 402]]

paragraph (b) of this section when the Administrator becomes aware of 
applicability.
    (2) Plan components. At a minimum, each mitigation plan developed 
under this paragraph shall contain provisions for the following:
    (i) Public notification to and education programs for affected or 
potentially affected communities. Such notification and education 
programs shall apply whenever air quality concentrations exceed or are 
expected to exceed a national ambient air quality standard with an 
averaging time that is less than or equal to 24-hours.
    (ii) Steps to identify, study and implement mitigating measures, 
including approaches to address each of the following:
    (A) Measures to abate or minimize contributing controllable sources 
of identified pollutants.
    (B) Methods to minimize public exposure to high concentrations of 
identified pollutants.
    (C) Processes to collect and maintain data pertinent to the event.
    (D) Mechanisms to consult with other air quality managers in the 
affected area regarding the appropriate responses to abate and minimize 
impacts.
    (iii) Provisions for periodic review and evaluation of the 
mitigation plan and its implementation and effectiveness by the State 
and all interested stakeholders.
    (A) With the submission of the initial mitigation plan according to 
the requirements in paragraph (b)(3) of this section that contains the 
elements in paragraph (b)(2) of this section, the State must:
    (1) Document that a draft version of the mitigation plan was 
available for public comment for a minimum of 30 days;
    (2) Submit the public comments it received along with its mitigation 
plan to the Administrator; and
    (3) In its submission to the Administrator, for each public comment 
received, explain the changes made to the mitigation plan or explain why 
the State did not make any changes to the mitigation plan.
    (B) The State shall specify in its mitigation plan the periodic 
review and evaluation process that it intends to follow for reviews 
following the initial review identified in paragraph (b)(2)(iii)(A) of 
this section.
    (3) Submission of mitigation plans. All States subject to the 
provisions of paragraph (b) of this section shall, after notice and 
opportunity for public comment identified in paragraph (b)(2)(iii)(A) of 
this section, submit a mitigation plan to the Administrator for review 
and verification of the plan components identified in paragraph (b)(2) 
of this section.
    (i) States shall submit their mitigation plans within 2 years of 
being notified that they are subject to the provisions of paragraph (b) 
of this section.
    (ii) The Administrator shall review each mitigation plan developed 
according to the requirements in paragraph (b)(2) of this section and 
shall notify the submitting State upon completion of such review.

[81 FR 68282, Oct. 3, 2016]



  Subpart Z_Provisions for Implementation of PM2.5 National 
                      Ambient Air Quality Standards

    Source: 81 FR 58151, Aug. 24, 2016, unless otherwise noted.



Sec. 51.1000  Definitions.

    The following definitions apply for purposes of this subpart. Any 
term not defined herein shall have the meaning as defined in 40 CFR 
51.100 or Clean Air Act section 302.
    Act means the Clean Air Act as codified at 42 U.S.C. 7401-7671q 
(2003).
    Additional feasible measure is any control measure that otherwise 
meets the definition of ``best available control measure'' (BACM) but 
can only be implemented in whole or in part beginning 4 years after the 
date of reclassification of an area as Serious and no later than the 
statutory attainment date for the area.
    Additional reasonable measure is any control measure that otherwise 
meets the definition of ``reasonably available control measure'' (RACM) 
but can only be implemented in whole or in part during the period 
beginning 4 years after the effective date of designation

[[Page 403]]

of a nonattainment area and no later than the end of the sixth calendar 
year following the effective date of designation of the area.
    Applicable annual standard is the annual PM2.5 NAAQS 
established, revised, or retained as a result of a particular 
PM2.5 NAAQS review.
    Applicable attainment date means the latest statutory date by which 
an area is required to attain a particular PM2.5 NAAQS, 
unless the EPA has approved an attainment plan for the area to attain 
such NAAQS, in which case the applicable attainment date is the date 
approved under such attainment plan. If the EPA grants an extension of 
an approved attainment date, then the applicable attainment date for the 
area shall be the extended date.
    Applicable 24-hour standard is the 24-hour PM2.5 NAAQS 
established, revised, or retained as a result of a particular 
PM2.5 NAAQS review.
    Attainment projected inventory for the nonattainment area means the 
projected emissions of direct PM2.5 and all PM2.5 
precursors on the projected attainment date for the area. This projected 
inventory includes sources included in the base year inventory for the 
nonattainment area revised to account for changes in direct 
PM2.5 and all PM2.5 precursors through 
implementation of the plan and any additional sources of such emissions 
expected within the boundaries of the nonattainment area by the 
projected attainment date for the area.
    Average-season-day emissions means the sum of all emissions during 
the applicable season divided by the number of days in that season.
    Base year inventory for the nonattainment area means the actual 
emissions of direct PM2.5 and all PM2.5 precursors 
from all sources within the boundaries of a nonattainment area in one of 
the 3 years used for purposes of designations or another technically 
appropriate year.
    Best available control measure (BACM) is any technologically and 
economically feasible control measure that can be implemented in whole 
or in part within 4 years after the date of reclassification of a 
Moderate PM2.5 nonattainment area to Serious and that 
generally can achieve greater permanent and enforceable emissions 
reductions in direct PM2.5 emissions and/or emissions of 
PM2.5 plan precursors from sources in the area than can be 
achieved through the implementation of RACM on the same source(s). BACM 
includes best available control technology (BACT).
    Date of designation means the effective date of a PM2.5 
area designation as promulgated by the Administrator.
    Date of reclassification means the effective date of a 
PM2.5 area reclassification from Moderate to Serious as 
promulgated by the Administrator.
    Direct PM2.5 emissions means solid or liquid particles 
emitted directly from an air emissions source or activity, or reaction 
products of gases emitted directly from an air emissions source or 
activity which form particulate matter as they reach ambient 
temperatures. Direct PM2.5 emissions include filterable and 
condensable PM2.5 emissions composed of elemental carbon, 
directly emitted organic carbon, directly emitted sulfate, directly 
emitted nitrate, and other organic or inorganic particles that exist or 
form through reactions as emissions reach ambient temperatures 
(including but not limited to crustal material, metals, and sea salt).
    Implemented means adopted by the state, fully approved into the SIP 
by the EPA, and requiring expeditious compliance by affected sources 
with installation and/or operation of any equipment, control device, 
process change, or other emission reduction activity.
    Major stationary source means any stationary source of air 
pollutant(s) that emits, or has the potential to emit 100 tons per year 
or more of direct PM2.5 or any PM2.5 precursor in 
any Moderate nonattainment area for the PM2.5 NAAQS, or 70 
tons per year or more of direct PM2.5 or any PM2.5 
precursor in any Serious nonattainment area for the PM2.5 
NAAQS.
    Mobile source means mobile sources as defined by 40 CFR 51.50.
    Most stringent measure (MSM) is any permanent and enforceable 
control measure that achieves the most stringent emissions reductions in 
direct PM2.5 emissions and/or emissions of PM2.5 
plan precursors from among

[[Page 404]]

those control measures which are either included in the SIP for any 
other NAAQS, or have been achieved in practice in any state, and that 
can feasibly be implemented in the relevant PM2.5 NAAQS 
nonattainment area.
    Nonpoint source means nonpoint sources as defined by 40 CFR 51.50.
    PM2.5 design value (DV) for a PM2.5 
nonattainment area is the highest of the 3-year average concentrations 
calculated for the ambient air quality monitors in the area, in 
accordance with 40 CFR part 50, appendix N.
    PM2.5 NAAQS are the fine particulate matter National 
Ambient Air Quality Standards codified at 40 CFR part 50.
    PM2.5 plan precursors are those PM2.5 
precursors required to be regulated in the applicable attainment plan 
and/or NNSR program.
    PM2.5 precursors are Sulfur dioxide (SO2), 
Oxides of nitrogen (NOX), Volatile organic compounds (VOC), 
and Ammonia (NH3).
    Point source means point sources as defined by 40 CFR 51.50.
    Precursor demonstration means an optional set of analyses provided 
by a state that are designed to show that emissions of a particular 
PM2.5 precursor do not contribute significantly to 
PM2.5 levels that exceed the relevant PM2.5 
standard in a particular nonattainment area. The three types of 
precursor demonstrations provided in this rule are the comprehensive 
precursor demonstration, the major stationary source precursor 
demonstration, and the NNSR precursor demonstration.
    Reasonable further progress (RFP) means such annual incremental 
reductions in emissions of direct PM2.5 and PM2.5 
plan precursors as are required for the purpose of ensuring attainment 
of the applicable PM2.5 NAAQS in a nonattainment area by the 
applicable attainment date.
    Reasonably available control measure (RACM) is any technologically 
and economically feasible measure that can be implemented in whole or in 
part within 4 years after the effective date of designation of a 
PM2.5 nonattainment area and that achieves permanent and 
enforceable reductions in direct PM2.5 emissions and/or 
PM2.5 plan precursor emissions from sources in the area. RACM 
includes reasonably available control technology (RACT).
    RFP projected emissions means the estimated emissions for direct 
PM2.5 and PM2.5 plan precursors by source category 
or subcategory for the years in which quantitative milestones are due 
for a nonattainment area.
    Subpart 1 means subpart 1 of part D of title I of the Act.
    Subpart 4 means subpart 4 of part D of title I of the Act.



Sec. 51.1001  Applicability of part 51.

    The provisions in subparts A through X of this part apply to areas 
for purposes of the PM2.5 NAAQS to the extent they are not 
inconsistent with the provisions of this subpart.



Sec. 51.1002  Classifications and reclassifications.

    (a) Initial classification as Moderate PM2.5 
nonattainment area. Any area designated nonattainment for a 
PM2.5 NAAQS shall be classified at the time of such 
designation, by operation of law, as a Moderate PM2.5 
nonattainment area.
    (b) Reclassification as Serious PM2.5 nonattainment area. 
A Moderate nonattainment area shall be reclassified to Serious under the 
following circumstances:
    (1) The EPA shall reclassify as Serious through notice-and-comment 
rulemaking any Moderate PM2.5 nonattainment area that the EPA 
determines cannot practicably attain a particular PM2.5 NAAQS 
by the applicable Moderate area attainment date.
    (2) A Moderate PM2.5 nonattainment area shall be 
reclassified by operation of law as a Serious nonattainment area if the 
EPA finds through notice-and-comment rulemaking that the area failed to 
attain a particular PM2.5 NAAQS by the applicable Moderate 
area attainment date.



Sec. 51.1003  Attainment plan due dates and submission requirements.

    (a) Nonattainment areas initially classified as Moderate. (1) For 
any area designated as nonattainment and initially classified as 
Moderate for a PM2.5 NAAQS, the state(s) shall submit a 
Moderate area attainment plan that

[[Page 405]]

meets all of the following requirements:
    (i) Base year emissions inventory requirements set forth at Sec. 
51.1008(a)(1);
    (ii) Attainment projected emissions inventory requirements set forth 
at Sec. 51.1008(a)(2);
    (iii) Moderate area attainment plan control strategy requirements 
set forth at Sec. 51.1009;
    (iv) Attainment demonstration and modeling requirements set forth at 
Sec. 51.1011;
    (v) Reasonable Further Progress (RFP) requirements set forth at 
Sec. 51.1012;
    (vi) Quantitative milestone requirements set forth at Sec. 51.1013;
    (vii) Contingency measure requirements set forth at Sec. 51.1014; 
and,
    (viii) Nonattainment new source review plan requirements pursuant to 
Sec. 51.165.
    (2) The state(s) shall submit its Moderate area attainment plan to 
the EPA no later than 18 months from the effective date of designation 
of the area.
    (b) Nonattainment areas reclassified to Serious. (1) For any 
nonattainment area reclassified to Serious for a PM2.5 NAAQS 
under Sec. 51.1002(b), in addition to meeting the Moderate area 
attainment plan submission requirements set forth at Sec. 51.1003(a), 
the state(s) shall submit a Serious area attainment plan that meets all 
of the following requirements:
    (i) Base year emissions inventory requirements set forth at Sec. 
51.1008(b)(1);
    (ii) Attainment projected emissions inventory requirements set forth 
at Sec. 51.1008(b)(2);
    (iii) Serious area attainment plan control strategy requirements set 
forth at Sec. 51.1010;
    (iv) Attainment demonstration and modeling requirements set forth at 
Sec. 51.1011;
    (v) Reasonable Further Progress (RFP) requirements set forth at 
Sec. 51.1012;
    (vi) Quantitative milestone requirements set forth at Sec. 51.1013;
    (vii) Contingency measure requirements set forth at Sec. 51.1014; 
and,
    (viii) Nonattainment new source review plan requirements pursuant to 
Sec. 51.165.
    (2) The state(s) shall submit its Serious area attainment plan to 
the EPA according to the following schedule:
    (i) Discretionary reclassification. (A) For any nonattainment area 
reclassified to Serious for a particular PM2.5 NAAQS under 
Sec. 51.1002(b)(1) because the EPA determined it cannot practicably 
attain the NAAQS by the applicable Moderate area attainment date, the 
state(s) shall submit to the EPA no later than 18 months from the 
effective date of reclassification the portion of the Serious area 
attainment plan that meets the following requirements:
    (1) Base year emissions inventory requirements set forth at Sec. 
51.1008(b)(1);
    (2) Serious area attainment plan control strategy requirements set 
forth at Sec. 51.1010(a)(1) through (4); and,
    (3) Nonattainment new source review plan requirements pursuant to 
Sec. 51.165.
    (B) The state(s) shall submit to the EPA the portion of the Serious 
area attainment plan that meets the requirements set forth at paragraphs 
(b)(1)(ii), and (b)(1)(iv) through (vii) of this section to the EPA by a 
date that is no later than 4 years after the effective date of 
reclassification, or 2 years prior to the attainment date, whichever is 
earlier.
    (ii) Mandatory reclassification. For any nonattainment area 
reclassified to Serious for a particular PM2.5 NAAQS under 
Sec. 51.1002(b)(2) because the EPA determined it failed to attain the 
NAAQS by the applicable Moderate area attainment date, the state(s) 
shall submit to the EPA a Serious area attainment plan meeting the 
requirements set forth at paragraphs (b)(1)(i) through (viii) of this 
section within 18 months from the effective date of reclassification, or 
2 years before the attainment date, whichever is earlier.
    (iii) If the state(s) submits to the EPA a request for a Serious 
area attainment date extension simultaneous with the Serious area 
attainment plan due under paragraph (b)(1) of this section, such a plan 
shall meet the most stringent measure (MSM) requirements set forth at 
Sec. 51.1010(b) in addition to the BACM and BACT and additional 
feasible measure requirements set forth at Sec. 51.1010(a).
    (c) Serious nonattainment areas subject to CAA section 189(d) for 
failing to attain

[[Page 406]]

the PM2.5 NAAQS by the applicable Serious area attainment 
date. (1) For any Serious nonattainment area that fails to attain the 
PM2.5 NAAQS by the applicable Serious area attainment date, 
the state(s) shall submit a revised Serious area attainment plan that 
demonstrates that each year the area will achieve at least a 5 percent 
reduction in emissions of direct PM2.5 or a 5 percent 
reduction in emissions of a PM2.5 plan precursor based on the 
most recent emissions inventory for the area. The revised attainment 
plan shall meet the following requirements:
    (i) Emissions inventory requirements set forth at Sec. 
51.1008(c)(1);
    (ii) Emissions inventory requirements set forth at Sec. 
51.1008(c)(2);
    (iii) Serious area attainment plan control strategy requirements set 
forth at Sec. 51.1010;
    (iv) Attainment demonstration and modeling requirements set forth at 
Sec. 51.1011;
    (v) Reasonable Further Progress (RFP) requirements set forth at 
Sec. 51.1012;
    (vi) Quantitative milestone requirements set forth at Sec. 51.1013;
    (vii) Contingency measure requirements set forth at Sec. 51.1014; 
and
    (viii) Nonattainment new source review plan requirements pursuant to 
Sec. 51.165.
    (2) The state(s) shall submit to the EPA the revised attainment plan 
meeting the requirements set forth at paragraphs (c)(1)(i) through (vii) 
of this section no later than 12 months from the applicable Serious area 
attainment date that was previously missed.
    (d) Any attainment plan submitted to the EPA under this section 
shall establish motor vehicle emissions budgets for the projected 
attainment year for the area, if applicable. The state shall develop 
such budgets according to the requirements of the transportation 
conformity rule as they apply to PM2.5 nonattainment areas 
(40 CFR part 93).



Sec. 51.1004  Attainment dates.

    (a) The state shall submit a projected attainment date as part of 
its attainment plan submission under Sec. 51.1003 for any 
PM2.5 NAAQS nonattainment area located in whole or in part 
within its boundaries. The state shall justify the projected attainment 
date for each such nonattainment area (or portion of a nonattainment 
area) as part of the demonstration of attainment developed and submitted 
according to the requirements set forth at Sec. 51.1011 and according 
to the following:
    (1) Nonattainment areas initially classified as Moderate.
    (i) Except for nonattainment areas that meet the criterion under 
paragraph (a)(1)(ii) of this section, the projected attainment date for 
a Moderate PM2.5 nonattainment area shall be as expeditious 
as practicable through the implementation of all control measures 
required under Sec. 51.1009. The attainment date may be as late as the 
end of the sixth calendar year after the effective date of designation 
if the state demonstrates that the implementation of the control 
measures that qualify as RACM, RACT, and additional reasonable measures, 
but that are not necessary for demonstrating attainment by the end of 
the sixth calendar year after the effective date of designation, will 
not collectively advance the attainment date by at least 1 year.
    (ii) The projected attainment date for a Moderate PM2.5 
nonattainment area which the state demonstrates cannot practicably 
attain the applicable PM2.5 NAAQS by the end of the sixth 
calendar year after the effective date of designation of the area with 
the implementation of all control measures required under Sec. 51.1009 
shall be the end of the sixth calendar year after the effective date of 
designation unless and until the area is reclassified as Serious 
according to Sec. 51.1002.
    (2) Nonattainment areas reclassified to Serious. (i) Except for 
nonattainment areas that meet the criterion under paragraph (a)(2)(ii) 
of this section, the projected attainment date for a Serious 
PM2.5 nonattainment area shall be as expeditious as 
practicable with the implementation of all control measures required 
under Sec. 51.1010 but no later than the end of the tenth calendar year 
after the effective date of designation.
    (ii) A state that submits an attainment plan that demonstrates that 
a Serious PM2.5 nonattainment area cannot practicably attain 
the PM2.5

[[Page 407]]

NAAQS by the end of the tenth calendar year following the effective date 
of designation of the area with the implementation of all control 
measures required under Sec. 51.1010(a) must request an extension of 
the Serious area attainment date consistent with Sec. 51.1005(b). The 
request must propose a projected attainment date for the nonattainment 
area that is as expeditious as practicable, but no later than the end of 
the fifteenth calendar year following the effective date of designation 
of the area.
    (3) Serious nonattainment areas subject to CAA section 189(d) for 
failing to attain by the applicable Serious area attainment date. The 
projected attainment date for a Serious PM2.5 nonattainment 
area that failed to attain the PM2.5 NAAQS by the applicable 
Serious area attainment date shall be as expeditious as practicable, but 
no later than 5 years following the effective date of the EPA's finding 
that the area failed to attain by the original Serious area attainment 
date, except that the Administrator may extend the attainment date to 
the extent the Administrator deems appropriate, for a period no greater 
than 10 years from the effective date of the EPA's determination that 
the area failed to attain, considering the severity of nonattainment and 
the availability and feasibility of pollution control measures.
    (b) Except for attainment plans that meet the conditions of 
paragraphs (a)(1)(ii) or (a)(3) of this section, the Administrator shall 
approve an attainment date at the same time and in the same manner in 
which the Administrator approves the attainment plan for the area.
    (1) In accordance with paragraph (a)(1)(ii) of this section, if a 
state demonstrates that a Moderate PM2.5 nonattainment area 
cannot practicably attain the PM2.5 NAAQS by the end of the 
sixth calendar year following the effective date of designation of the 
area, the EPA shall proceed under the provisions of Sec. 51.1002(b)(1) 
to reclassify the area to Serious through notice-and-comment rulemaking.
    (2) [Reserved]



Sec. 51.1005  Attainment date extensions.

    (a) Nonattainment areas initially classified as Moderate. (1) A 
state with a Moderate PM2.5 nonattainment area may apply for 
a 1-year attainment date extension for the area if the following 
conditions are met in the calendar year that includes the applicable 
attainment date for the area:
    (i) The state has complied with all requirements and commitments 
pertaining to the area in the applicable implementation plan;
    (ii) For an area designated nonattainment for a particular 24-hour 
PM2.5 NAAQS for which the state seeks an attainment date 
extension, the 98th percentile 24-hour concentration at each monitor in 
the area for the calendar year that includes the applicable attainment 
date is less than or equal to the level of the applicable 24-hour 
standard (calculated according to the data analysis requirements in 40 
CFR part 50, appendix N);
    (iii) For an area designated nonattainment for a particular annual 
PM2.5 NAAQS for which the state seeks an attainment date 
extension, the annual average concentration at each monitor in the area 
for the calendar year that includes the applicable attainment date is 
less than or equal to the level of the applicable annual standard 
(calculated according to the data analysis requirements in 40 CFR part 
50, appendix N).
    (2) The applicable implementation plan for a Moderate 
PM2.5 nonattainment area for which a state seeks an 
attainment date extension is the plan submitted to the EPA to meet the 
requirements of Sec. 51.1003(a).
    (3) A Moderate area 1-year attainment date extension runs from 
January 1 to December 31 of the year following the year that includes 
the applicable attainment date.
    (4) A state with a Moderate area that received an initial 1-year 
attainment date extension may apply for a second 1-year attainment date 
extension for the area if the state meets the conditions described in 
paragraph (a)(1) of this section for the first 1-year extension year.
    (b) Nonattainment areas reclassified as Serious. (1) A state may 
apply for one

[[Page 408]]

attainment date extension not to exceed 5 years for a Serious 
nonattainment area if the following conditions are met:
    (i) The state demonstrates that attainment of the applicable 
PM2.5 NAAQS by the approved attainment date for the area 
would be impracticable or, in the absence of an approved attainment 
date, attainment of the applicable PM2.5 NAAQS by the 
applicable statutory attainment date for the area would be 
impracticable;
    (ii) The state has complied with all requirements and commitments 
pertaining to the area in the applicable implementation plan; and,
    (iii) The state demonstrates that the attainment plan for the area 
includes the most stringent measures (MSM) that are included in the 
attainment plan of any state or are achieved in practice in any state, 
and can feasibly be implemented in the area consistent with Sec. 
51.1010(b).
    (2) At the time of application for an attainment date extension, the 
state shall submit to the EPA a Serious area attainment plan that meets 
the following requirements:
    (i) Base year and attainment projected emissions inventory 
requirements set forth at Sec. 51.1008(b);
    (ii) Most stringent measures (MSM) requirement described under 
paragraph (b)(1)(iii) of this section and Sec. 51.1010(b), and best 
available control measures not previously submitted;
    (iii) Attainment demonstration and modeling requirements set forth 
at Sec. 51.1011 that justify the state's conclusion under paragraph 
(b)(1)(i) of this section, and that demonstrate attainment as 
expeditiously as practicable;
    (iv) Reasonable Further Progress (RFP) requirements set forth at 
Sec. 51.1012;
    (v) Quantitative milestone requirements set forth at Sec. 51.1013;
    (vi) Contingency measure requirements set forth at Sec. 51.1014; 
and,
    (vii) Nonattainment new source review plan requirements pursuant to 
Sec. 51.165.
    (3) The applicable implementation plan for a Serious 
PM2.5 nonattainment area for which a state seeks an 
attainment date extension under Sec. 51.1004(a)(2)(ii) is the plan 
submitted to the EPA to meet the requirements set forth at Sec. 
51.1003(a).
    (4) The applicable implementation plan for a Serious 
PM2.5 nonattainment area for which a state seeks an 
attainment date extension under Sec. 51.1004(a)(2)(i) is the plan 
submitted to the EPA to meet the requirements set forth at Sec. 
51.1003(b)(1).
    (5) A state applying for an attainment date extension for a Serious 
nonattainment area under Sec. 51.1004(a)(2)(ii) shall submit to the EPA 
a request for an extension at the same time as it submits the Serious 
area attainment plan due under Sec. 51.1003(b)(1).
    (6) A state applying for an attainment date extension for a Serious 
nonattainment area subsequent to submitting an initial Serious area 
attainment plan that demonstrated attainment of the NAAQS by the 
applicable attainment date consistent with Sec. 51.1004(a)(2)(i) at the 
time of submission may apply for such an extension no later than 60 
calendar days prior to the approved attainment date for the area or, in 
the absence of an approved attainment date, no later than 60 calendar 
days prior to the applicable statutory attainment date for the area.
    (c) Serious nonattainment areas subject to CAA section 189(d) for 
failing to attain by the applicable Serious area attainment date. If a 
Serious area fails to attain a particular PM2.5 NAAQS by the 
applicable Serious area attainment date, the area is then subject to the 
requirements of section 189(d) of the Act, and, for this reason, the 
state is prohibited from requesting an extension of the applicable 
Serious area attainment date for such area.
    (d) For any attainment date extension request submitted pursuant to 
this section, the requesting state (or states) shall submit a written 
request and evidence of compliance with these regulations which includes 
both of the following:
    (1) Evidence that all control measures submitted in the applicable 
attainment plan have been implemented, and
    (2) Evidence that the area has made emission reduction progress that 
represents reasonable further progress toward timely attainment of the 
applicable PM2.5 NAAQS.

[[Page 409]]

    (e) For a PM2.5 nonattainment area located in two or more 
states or jurisdictions, all states and/or jurisdictions in which such 
area is located shall submit separate attainment date extension requests 
for the area consistent with the requirements set forth at paragraph (d) 
of this section.



Sec. 51.1006  Optional PM2.5 precursor demonstrations

    (a) A state may elect to submit to the EPA one or more precursor 
demonstrations for a specific nonattainment area. The analyses conducted 
in support of any precursor demonstration must be based on precursor 
emissions attributed to sources and activities in the nonattainment 
area.
    (1) A comprehensive precursor demonstration must show that emissions 
of a particular precursor from all existing stationary, area, and mobile 
sources located in the nonattainment area do not contribute 
significantly to PM2.5 levels that exceed the standard in the 
area. If the state chooses to conduct a comprehensive precursor 
demonstration, the state must conduct the analysis in paragraph 
(a)(1)(i) of this section and it may conduct the analysis in paragraph 
(a)(1)(ii) of this section.
    (i) Concentration-based contribution analysis. The comprehensive 
precursor demonstration must evaluate the contribution of a particular 
precursor to PM2.5 levels in the area. If the contribution of 
the precursor to PM2.5 levels in the area is not significant, 
based on the facts and circumstances of the area, then the EPA may 
approve the demonstration.
    (ii) Sensitivity-based contribution analysis. If the concentration-
based contribution analysis does not support a finding of insignificant 
contribution, based on the facts and circumstances of the area, then the 
state may choose to submit an analysis evaluating the sensitivity of 
PM2.5 levels in the area to a decrease in emissions of the 
precursor in order to determine whether the resulting air quality 
changes are significant. If the estimated air quality changes determined 
in the sensitivity analysis are not significant, based on the facts and 
circumstances of the area, then the EPA may approve the demonstration.
    (iii) If a comprehensive precursor demonstration is approved by the 
EPA, the state will not be required to control emissions of the relevant 
precursor from existing sources in the current attainment plan.
    (2) A major stationary source precursor demonstration must show that 
emissions of a particular precursor from all existing major stationary 
sources located in the nonattainment area do not contribute 
significantly to PM2.5 levels that exceed the standard in the 
area. If the state chooses to conduct a major stationary source 
precursor demonstration, the state must conduct the analysis in 
paragraph (a)(2)(i) of this section and it may conduct the analysis in 
paragraph (a)(2)(ii) of this section.
    (i) Concentration-based contribution analysis. The major stationary 
source precursor demonstration must evaluate the contribution of major 
source emissions of a particular precursor to PM2.5 levels in 
the area. If the contribution of the precursor to PM2.5 
levels in the area is not significant, based on the facts and 
circumstances of the area, then the EPA may approve the demonstration.
    (ii) Sensitivity-based contribution analysis. If the concentration-
based contribution analysis does not support a finding of insignificant 
contribution, based on the facts and circumstances of the area, then the 
state may choose to submit an analysis evaluating the sensitivity of 
PM2.5 levels in the area to a decrease in emissions of the 
precursor in order to determine whether the resulting air quality 
changes are significant. If the estimated air quality changes determined 
in the sensitivity analysis are not significant, based on the facts and 
circumstances of the area, then the EPA may approve the demonstration.
    (iii) If a major stationary source precursor demonstration is 
approved by the EPA, the state will not be required to control emissions 
of the relevant precursor from existing major stationary sources in the 
current attainment plan.
    (3)(i) A NNSR precursor demonstration must evaluate the sensitivity 
of PM2.5 levels in the nonattainment area

[[Page 410]]

to an increase in emissions of a particular precursor in order to 
determine whether the resulting air quality changes are significant. If 
the estimated air quality changes determined in the sensitivity analysis 
are not significant, based on the facts and circumstances of the area, 
the state may use that information to identify new major stationary 
sources and major modifications of a precursor that will not be 
considered to contribute significantly to PM2.5 levels that 
exceed the standard in the nonattainment area.
    (ii) If a NNSR precursor demonstration for a particular 
PM2.5 nonattainment area is approved, the state may exempt 
such new major stationary sources or major modifications of the 
particular precursor from the requirements for PM2.5 in Sec. 
51.165.
    (b) If an area with one or more precursor demonstrations approved by 
the EPA is required to submit another PM2.5 attainment plan 
in accordance with Sec. 51.1003 of this part, the current precursor 
demonstration(s) will not apply to the new plan. The state must submit 
the appropriate updated precursor demonstration(s) if it seeks to exempt 
sources of a particular precursor from control requirements in the new 
Serious area attainment demonstration or in the NNSR program for the 
Serious area.



Sec. 51.1007  [Reserved]



Sec. 51.1008  Emissions inventory requirements.

    (a) For any nonattainment area initially classified as Moderate, the 
state shall submit to the EPA all of the following:
    (1) A base year inventory for the nonattainment area for all 
emissions sources that meets the following minimum criteria:
    (i) The inventory year shall be one of the 3 years for which 
monitored data were used for designations or another technically 
appropriate inventory year if justified by the state in the plan 
submission.
    (ii) The inventory shall include actual emissions of all sources 
within the nonattainment area.
    (iii) The emissions values shall be either annual total emissions, 
average-season-day emissions, or both, as appropriate for the relevant 
PM2.5 NAAQS. The state shall include as part of the plan a 
rationale for providing annual or seasonal emissions, and the 
justification for the period used for any seasonal emissions 
calculations.
    (iv) The inventory shall include direct PM2.5 emissions, 
separately reported PM2.5 filterable and condensable 
emissions, and emissions of the scientific PM2.5 precursors, 
including precursors that are not PM2.5 plan precursors 
pursuant to a precursor demonstration under Sec. 51.1006.
    (v) The state shall report emissions as point sources according to 
the point source emissions thresholds of the Air Emissions Reporting 
Requirements (AERR), 40 CFR part 51, subpart A.
    (vi) The detail of the emissions inventory shall be consistent with 
the detail and data elements required by 40 CFR part 51, subpart A.
    (2) An attainment projected inventory for the nonattainment area 
that meets the following minimum criteria:
    (i) The year of the projected inventory shall be the most 
expeditious year for which projected emissions show modeled 
PM2.5 concentrations below the level of the NAAQS.
    (ii) The emissions values shall be projected emissions of the same 
sources included in the base year inventory for the nonattainment area 
(i.e., those only within the nonattainment area) and any new sources. 
The state shall include in this inventory projected emissions growth and 
contraction from both controls and other causes during the relevant 
period.
    (iii) The temporal period of emissions shall be the same temporal 
period (annual, average-season-day, or both) as the base year inventory 
for the nonattainment area.
    (iv) Consistent with the base year inventory for the nonattainment 
area, the inventory shall include direct PM2.5 emissions, 
separately reported PM2.5 filterable and condensable 
emissions, and emissions of the scientific PM2.5 precursors, 
including precursors that are not PM2.5 plan precursors 
pursuant to a precursor demonstration under Sec. 51.1006 of this part.

[[Page 411]]

    (v) The same sources reported as point sources in the base year 
inventory for the nonattainment area shall be included as point sources 
in the attainment projected inventory for the nonattainment area. 
Stationary nonpoint and mobile source projected emissions shall be 
provided using the same detail (e.g., state, county, and process codes) 
as the base year inventory for the nonattainment area.
    (vi) The same detail of the emissions included shall be consistent 
with the level of detail and data elements as in the base year inventory 
for the nonattainment area (i.e., as required by 40 CFR part 41, subpart 
A).
    (b) For any nonattainment area reclassified as Serious, the state 
shall submit to the EPA all of the following:
    (1) For purposes of meeting the emissions inventory requirements of 
CAA section 172(c)(3), a base year inventory for the nonattainment area 
for all emissions sources that meets the requirements listed under 
paragraphs (a)(1) (ii) through (a)(1)(vi) of this section. In addition, 
the inventory shall use the Serious area definition of a major source 
listed under Sec. 51.165(a)(1)(iv)(A), and(a)(1)(vii) and (viii), and 
consistent with Table 1 of Appendix A to subpart A of this part in 
determining sources to include as point sources. Finally, the inventory 
year shall be one of the 3 years for which monitored data were used for 
reclassification to Serious, or another technically appropriate 
inventory year if justified by the state in the plan submission.
    (2) An attainment projected inventory for the nonattainment area 
that meets the criteria listed under paragraph (a)(2) of this section.
    (c) Serious nonattainment areas subject to CAA section 189(d) for 
failing to attain a PM2.5 NAAQS by the applicable Serious 
area attainment date. No later than 12 months after the EPA finds 
through notice-and-comment rulemaking that a Serious nonattainment area, 
or portion thereof contained within a state's borders, fails to attain a 
PM2.5 NAAQS by the applicable attainment date and thus 
becomes subject to the requirements under CAA section 189(d), the state 
shall submit to the EPA all of the following:
    (1) For purposes of meeting the emissions inventory requirements of 
CAA section 172(c)(3), a base year inventory for the nonattainment area 
for all emissions sources that meets the requirements listed under 
paragraphs (a)(1) (ii) through (a)(1)(vi) of this section. In addition, 
the inventory shall use the Serious area definition of a major source 
listed under Sec. 51.165(a)(1)(iv)(A)(vii) and (viii) and consistent 
with Table 1 of Appendix A to subpart A of this part in determining 
sources to include as point sources. The inventory year shall be one of 
the 3 years for which monitored data were used to determine that the 
area failed to attain the PM2.5 NAAQS by the applicable 
Serious area attainment date, or another technically appropriate 
inventory year if justified by the state in the plan submission.
    (2) An attainment projected inventory for the nonattainment area as 
defined by Sec. 51.1000(e) and that meets the criteria listed under 
paragraph (a)(2) of this section.



Sec. 51.1009  Moderate area attainment plan control strategy requirements.

    (a) The state shall identify, adopt, and implement control measures, 
including control technologies, on sources of direct PM2.5 
emissions and sources of emissions of PM2.5 plan precursors 
located in any Moderate PM2.5 nonattainment area or portion 
thereof located within the state consistent with the following:
    (1) The state shall identify all sources of direct PM2.5 
emissions and all sources of emissions of PM2.5 precursors in 
the nonattainment area in accordance with the emissions inventory 
requirements of Sec. 51.1008(a).
    (2) The state shall identify all potential control measures to 
reduce emissions from all sources of direct PM2.5 emissions 
and all sources of emissions of PM2.5 plan precursors in the 
nonattainment area identified under paragraph (a)(1) of this section.
    (i) The state is not required to identify and evaluate potential 
control measures to reduce emissions of a particular PM2.5 
precursor from any existing sources if the state has submitted a 
comprehensive precursor demonstration approved by the EPA pursuant to

[[Page 412]]

Sec. 51.1006, except where the EPA requires such information as 
necessary to evaluate the comprehensive precursor demonstration pursuant 
to Sec. 51.1006(a)(1)(ii).
    (ii) The state is not required to identify and evaluate potential 
control measures to reduce emissions of a particular PM2.5 
precursor from any existing major stationary sources if the state has 
submitted a major stationary source precursor demonstration approved by 
the EPA pursuant to Sec. 51.1006, except where the EPA requires such 
information as necessary to evaluate the major stationary source 
precursor demonstration pursuant to Sec. 51.1006(a)(1)(ii).
    (3) For any potential control measure identified under paragraph 
(a)(2) of this section, the state may make a demonstration that such 
measure is not technologically or economically feasible to implement in 
whole or in part by the end of the sixth calendar year following the 
effective date of designation of the area, and the state may eliminate 
such whole or partial measure from further consideration under this 
paragraph.
    (i) For purposes of evaluating the technological feasibility of a 
potential control measure, the state may consider factors including but 
not limited to a source's processes and operating procedures, raw 
materials, physical plant layout, and potential environmental impacts 
such as increased water pollution, waste disposal, and energy 
requirements.
    (ii) For purposes of evaluating the economic feasibility of a 
potential control measure, the state may consider factors including but 
not limited to capital costs, operating and maintenance costs, and cost 
effectiveness of the measure.
    (iii) The state must submit to the EPA as part of its Moderate area 
attainment plan a detailed written justification for eliminating from 
further consideration any potential control measure identified under 
paragraph (a)(2) of this section on the basis of technological or 
economic infeasibility.
    (4) The state shall use air quality modeling that meets the 
requirements of Sec. 51.1011(a) and that accounts for emissions 
reductions estimated due to all technologically and economically 
feasible control measures identified for sources of direct 
PM2.5 emissions and sources of emissions of PM2.5 
plan precursors in the Moderate PM2.5 nonattainment area to 
demonstrate that the area can attain the applicable PM2.5 
NAAQS as expeditiously as practicable but no later than the end of the 
sixth year following the effective date of designation of the area. The 
state may use air quality modeling to demonstrate that the Moderate 
PM2.5 nonattainment area cannot practicably attain the 
applicable PM2.5 NAAQS by such date.
    (i) If the state demonstrates through air quality modeling that the 
area can attain the applicable PM2.5 NAAQS by the end of the 
sixth calendar year following the effective date of designation of the 
area, the state shall adopt and implement all technologically and 
economically feasible control measures identified under paragraph (a)(3) 
of this section that are necessary to bring the area into attainment by 
such date. The state shall also adopt and implement all other 
technologically and economically feasible measures identified under 
paragraph (a)(3) of this section that, when considered collectively, 
would advance the attainment date for the area by at least 1 year. If 
the state demonstrates through this analysis that control measures for 
reducing emissions of a PM2.5 precursor would not be 
necessary for attainment as expeditiously as practicable or to advance 
the attainment date, then the state would not be required to include 
control measures for the precursor in the Moderate area attainment plan, 
nor be required to address the precursor in the RFP plan, quantitative 
milestones and associated reports, and contingency measures.
    (A) Any control measure identified for adoption and implementation 
under this paragraph that can be implemented in whole or in part by 4 
years after the effective date of designation of the Moderate 
PM2.5 nonattainment area shall be considered RACM for the 
area. Any such control measure that is also a control technology shall 
be considered RACT for the area.

[[Page 413]]

    (B) Any control measure identified for adoption and implementation 
under this paragraph that can only be implemented in whole or in part 
during the period beginning 4 years after the effective date of 
designation of the Moderate PM2.5 nonattainment area and the 
applicable attainment date for the area shall be considered an 
additional reasonable measure for the area.
    (ii) If the state demonstrates that the area cannot practicably 
attain the applicable PM2.5 NAAQS by the end of the sixth 
calendar year following the effective date of designation of the area, 
the state shall adopt all technologically and economically feasible 
control measures identified under paragraph (a)(3) of this section. This 
requirement also applies to areas that demonstrate pursuant to section 
179B that the plan would be adequate to attain or maintain the standard 
but for emissions emanating from outside the United States.
    (A) Any control measure identified for adoption and implementation 
under this paragraph that can be implemented in whole or in part by 4 
years after the effective date of designation of the Moderate 
PM2.5 nonattainment area shall be considered RACM for the 
area. Any such control measure that is also a control technology shall 
be considered RACT for the area.
    (B) Any control measure identified for adoption and implementation 
under this paragraph that can only be implemented in whole or in part 
during the period beginning 4 years after the effective date of 
designation of the Moderate PM2.5 nonattainment area through 
the end of the sixth calendar year following the effective date of 
designation of the area shall be considered an additional reasonable 
measure for the area.
    (b) The state shall adopt control measures, including control 
technologies, on sources of direct PM2.5 emissions and 
sources of emissions of PM2.5 plan precursors located within 
the state but outside the Moderate PM2.5 nonattainment area 
if adopting such control measures is necessary to provide for attainment 
of the applicable PM2.5 NAAQS in such area.
    (c) For new or revised source emissions limitations on sources of 
direct PM2.5 emissions, the state shall establish such 
emission limitations to apply either to the total of the filterable plus 
condensable fractions of direct PM2.5, or to filterable 
PM2.5 and condensable PM2.5 separately.



Sec. 51.1010  Serious area attainment plan control strategy
requirements.

    (a) The state shall identify, adopt, and implement best available 
control measures, including control technologies, on sources of direct 
PM2.5 emissions and sources of emissions of PM2.5 
plan precursors located in any Serious PM2.5 nonattainment 
area or portion thereof located within the state and consistent with the 
following:
    (1) The state shall identify all sources of direct PM2.5 
emissions and all sources of emissions of PM2.5 precursors in 
the nonattainment area in accordance with the emissions inventory 
requirements of Sec. 51.1008(b).
    (2) The state shall identify all potential control measures to 
reduce emissions from all sources of direct PM2.5 emissions 
and sources of emissions of PM2.5 plan precursors in the 
nonattainment area identified under paragraph (a)(1) of this section.
    (i) The state shall survey other NAAQS nonattainment areas in the 
U.S. and identify any measures for direct PM2.5 and 
PM2.5 plan precursors not previously identified by the state 
during the development of the Moderate area attainment plan for the 
area.
    (ii) The state is not required to identify and evaluate potential 
control measures to reduce emissions of a particular PM2.5 
precursor from any existing sources if the state has submitted a 
comprehensive precursor demonstration approved by the EPA, except where 
the EPA requires such information as necessary to evaluate the 
comprehensive precursor demonstration pursuant to Sec. 
51.1006(a)(1)(ii).
    (iii) The state is not required to identify and evaluate potential 
control measures to reduce emissions of a particular PM2.5 
precursor from any existing major stationary sources if the state has 
submitted a major stationary source precursor demonstration approved by 
the EPA, except where the

[[Page 414]]

EPA requires such information as necessary to evaluate the major 
stationary source demonstration pursuant to Sec. 51.1006(a)(1)(ii).
    (3) The state may make a demonstration that any measure identified 
under paragraph (a)(2) of this section is not technologically or 
economically feasible to implement in whole or in part by the end of the 
tenth calendar year following the effective date of designation of the 
area, and may eliminate such whole or partial measure from further 
consideration under this paragraph.
    (i) For purposes of evaluating the technological feasibility of a 
potential control measure, the state may consider factors including but 
not limited to a source's processes and operating procedures, raw 
materials, physical plant layout, and potential environmental impacts 
such as increased water pollution, waste disposal, and energy 
requirements.
    (ii) For purposes of evaluating the economic feasibility of a 
potential control measure, the state may consider capital costs, 
operating and maintenance costs, and cost effectiveness of the measure.
    (iii) The state shall submit to the EPA as part of its Serious area 
attainment plan submission a detailed written justification for 
eliminating from further consideration any potential control measure 
identified under paragraph (a)(2) of this section on the basis of 
technological or economic infeasibility. The state shall provide as part 
of its written justification an explanation of how its criteria for 
determining the technological and economic feasibility of potential 
control measures under paragraphs (a)(3)(i) and (ii) of this section are 
more stringent than its criteria for determining the technological and 
economic feasibility of potential control measures under Sec. 
51.1009(a)(3)(i) and (ii) for the same sources in the PM2.5 
nonattainment area.
    (4) Except as provided under paragraph (a)(3) of this section, the 
state shall adopt and implement all potential control measures 
identified under paragraph (a)(2) of this section.
    (i) Any control measure that can be implemented in whole or in part 
by the end of the fourth year following the date of reclassification of 
the area to Serious shall be considered a best available control measure 
for the area. Any such control measure that is also a control technology 
for a stationary source in the area shall be considered a best available 
control technology for the area.
    (ii) Any control measure that can be implemented in whole or in part 
between the end of the fourth year following the date of 
reclassification of the area to Serious and the applicable attainment 
date for the area shall be considered an additional feasible measure.
    (5) The state shall use air quality modeling that meets the 
requirements of Sec. 51.1011(b) and that accounts for emissions 
reductions estimated due to all best available control measures, 
including best available control technologies, and additional feasible 
measures identified for sources of direct PM2.5 emissions and 
sources of emissions of PM2.5 plan precursors in the area to 
demonstrate that the area can attain the PM2.5 NAAQS as 
expeditiously as practicable but no later than the end of the tenth 
calendar year following the effective date of designation of the area, 
or to demonstrate that the Serious PM2.5 nonattainment area 
cannot practicably attain the applicable PM2.5 NAAQS by such 
date.
    (b) For a Serious PM2.5 nonattainment area for which air 
quality modeling demonstrates the area cannot practicably attain the 
applicable PM2.5 NAAQS by the end of the tenth calendar year 
following the date of designation of the area, the state shall identify, 
adopt, and implement the most stringent control measures that are 
included in the attainment plan for any state or are achieved in 
practice in any state, and can be feasibly implemented in the area, 
consistent with the following requirements.
    (1) The state shall identify all sources of direct PM2.5 
emissions and sources of emissions of PM2.5 precursors in the 
nonattainment area in accordance with the emissions inventory 
requirements of Sec. 51.1008(b).
    (2) The state shall identify all potential control measures to 
reduce emissions from all sources of direct PM2.5

[[Page 415]]

emissions and sources of emissions of PM2.5 plan precursors 
in the nonattainment area identified under paragraph (b)(1) of this 
section.
    (i) For the sources and source categories represented in the 
emission inventory for the nonattainment area, the state shall identify 
the most stringent measures for reducing direct PM2.5 and 
PM2.5 plan precursors adopted into any SIP or used in 
practice to control emissions in any state.
    (ii) The state shall reconsider and reassess any measures previously 
rejected by the state during the development of any previous Moderate 
area or Serious area attainment plan control strategy for the area.
    (3) The state may make a demonstration that a measure identified 
under paragraph (b)(2) of this section is not technologically or 
economically feasible to implement in whole or in part by 5 years after 
the applicable attainment date for the area, and may eliminate such 
whole or partial measure from further consideration under this 
paragraph.
    (i) For purposes of evaluating the technological feasibility of a 
potential control measure, the state may consider factors including but 
not limited to a source's processes and operating procedures, raw 
materials, physical plant layout, and potential environmental impacts 
such as increased water pollution, waste disposal, and energy 
requirements.
    (ii) For purposes of evaluating the economic feasibility of a 
potential control measure, the state may consider capital costs, 
operating and maintenance costs, and cost effectiveness of the measure.
    (iii) The state shall submit to the EPA as part of its Serious area 
attainment plan submission a detailed written justification for 
eliminating from further consideration any potential control measure 
identified under paragraph (b)(2) of this section on the basis of 
technological or economic infeasibility.
    (4) Except as provided under paragraph (b)(3) of this section, the 
state shall adopt and implement all control measures identified under 
paragraph (b)(2) of this section that collectively shall achieve 
attainment as expeditiously as practicable but no later than 5 years 
after the applicable attainment date for the area.
    (5) The state shall use air quality modeling that meets the 
requirements of Sec. 51.1011(b) and that accounts for emissions 
reductions estimated due to all most stringent measures; best available 
control measures, including best available control technologies; and 
additional feasible measures identified for sources of direct 
PM2.5 emissions and sources of emissions of PM2.5 
plan precursors in the area to demonstrate that the area can attain the 
PM2.5 NAAQS as expeditiously as practicable but no later than 
the end of the fifteenth calendar year following the effective date of 
designation of the area.
    (c) For a Serious PM2.5 nonattainment area that the EPA 
has determined has failed to attain by the applicable attainment date, 
the state shall submit a revised attainment plan with a control strategy 
that demonstrates that each year the area will achieve at least a 5 
percent reduction in emissions of direct PM2.5 or a 5 percent 
reduction in emissions of a PM2.5 plan precursor based on the 
most recent emissions inventory for the area; and that the area will 
attain the standard as expeditiously as practicable consistent with 
Sec. 51.1004(a)(3). The plan shall meet the requirements of Sec. 
51.1003(c)-(d), and the following requirements:
    (1) The state shall identify all sources of direct PM2.5 
emissions and sources of emissions of PM2.5 precursors in the 
nonattainment area in accordance with the emissions inventory 
requirements of Sec. 51.1008(b).
    (2) The state shall identify all potential control measures to 
reduce emissions from all sources of direct PM2.5 emissions 
and sources of emissions of PM2.5 plan precursors in the 
nonattainment area identified under paragraph (c)(1) of this section.
    (i) For the sources and source categories represented in the 
emission inventory for the nonattainment area, the state shall identify 
the most stringent measures for reducing direct PM2.5 and 
PM2.5 plan precursors adopted into any SIP or used in 
practice to control emissions in any state, as applicable.

[[Page 416]]

    (ii) The state shall reconsider and reassess any measures previously 
rejected by the state during the development of any Moderate area or 
Serious area attainment plan control strategy for the area.
    (3) The state may make a demonstration that a measure identified 
under paragraph (c)(2) of this section is not technologically or 
economically feasible to implement in whole or in part within 5 years or 
such longer period as the EPA may determine is appropriate after the 
EPA's determination that the area failed to attain by the Serious area 
attainment date, and may eliminate such whole or partial measure from 
further consideration under this paragraph.
    (i) For purposes of evaluating the technological feasibility of a 
potential control measure, the state may consider factors including but 
not limited to a source's processes and operating procedures, raw 
materials, physical plant layout, and potential environmental impacts 
such as increased water pollution, waste disposal, and energy 
requirements.
    (ii) For purposes of evaluating the economic feasibility of a 
potential control measure, the state may consider capital costs, 
operating and maintenance costs, and cost effectiveness of the measure.
    (iii) The state shall submit to the EPA as part of its Serious area 
attainment plan submission a detailed written justification for 
eliminating from further consideration any potential control measure 
identified under paragraph (c)(2) of this section on the basis of 
technological or economic infeasibility.
    (4) Except as provided under paragraph (c)(3) of this section, the 
state shall adopt and implement all control measures identified under 
paragraph (c)(2) of this section that collectively achieve attainment of 
the standard as expeditiously as practicable pursuant to Sec. 
51.1004(a)(3).
    (5) The state shall conduct air quality modeling that meets the 
requirements of Sec. 51.1011(b) and that accounts for emissions 
reductions due to control measures needed to meet the annual reduction 
requirement of 5 percent of direct PM2.5 or a 
PM2.5 plan precursor; most stringent measures; best available 
control measures, including best available control technologies; and 
additional feasible measures identified for sources of direct 
PM2.5 emissions and sources of emissions of PM2.5 
plan precursors in the area in order to demonstrate that the area can 
attain the PM2.5 NAAQS as expeditiously as practicable.
    (d) The state shall adopt control measures, including control 
technologies, on sources of direct PM2.5 emissions and 
sources of emissions of PM2.5 plan precursors located within 
the state but outside the Serious PM2.5 nonattainment area if 
adopting such control measures is necessary to provide for attainment of 
the applicable PM2.5 NAAQS in such area by the attainment 
date.
    (e) For new or revised source emissions limitations on sources of 
direct PM2.5 emissions, the state shall establish such 
emission limitations to apply either to the total of the filterable plus 
condensable fractions of direct PM2.5, or to filterable 
PM2.5 and condensable PM2.5 separately.



Sec. 51.1011  Attainment demonstration and modeling requirements.

    (a) Nonattainment areas initially classified as Moderate. The 
attainment demonstration due to the EPA as part of any Moderate area 
attainment plan required under Sec. 51.1003(a) shall meet all of the 
following criteria:
    (1) The attainment demonstration shall show the projected attainment 
date for the Moderate nonattainment area that is as expeditious as 
practicable in accordance with the requirements of Sec. 51.1004(a)(1).
    (2) The attainment demonstration shall meet the requirements of 
Appendix W of this part and shall include inventory data, modeling 
results, and emission reduction analyses on which the state has based 
its projected attainment date.
    (3) The base year for the emissions inventory required for an 
attainment demonstration under this paragraph shall be one of the 3 
years used for designations or another technically appropriate inventory 
year if justified by the state in the plan submission.

[[Page 417]]

    (4) The control strategies modeled as part of the attainment 
demonstration shall be consistent with the following as applicable:
    (i) For a Moderate area that can demonstrate attainment of the 
applicable PM2.5 NAAQS no later than the end of the sixth 
calendar year following the date of designation of the area with the 
implementation of RACM and RACT and additional reasonable measures, the 
control strategies modeled as part of the attainment demonstration shall 
be consistent with control strategy requirements under Sec. 51.1009(a).
    (ii) For a Moderate area that cannot practicably attain the 
applicable PM2.5 NAAQS by the end of the sixth calendar year 
following the date of designation of the area with the implementation of 
RACM and RACT and additional reasonable measures, the control strategies 
modeled as part of the attainment demonstration shall be consistent with 
control strategy requirements under Sec. 51.1009(b).
    (5) Required time frame for obtaining emissions reductions. For each 
Moderate nonattainment area, the attainment plan must provide for 
implementation of all control measures needed for attainment as 
expeditiously as practicable. All control measures in the attainment 
demonstration must be implemented no later than the beginning of the 
year containing the applicable attainment date, notwithstanding RACM 
implementation deadline requirements in Sec. 51.1009.
    (b) Nonattainment areas reclassified as Serious. The attainment 
demonstration due to the EPA as part of a Serious area attainment plan 
required under Sec. 51.1003(b) or (c) shall meet all of the following 
criteria:
    (1) The attainment demonstration shall show the projected attainment 
date for the Serious nonattainment area that is as expeditious as 
practicable.
    (2) The attainment demonstration shall meet the requirements of 
Appendix W of this part and shall include inventory data, modeling 
results, and emission reduction analyses on which the state has based 
its projected attainment date.
    (3) The base year for the emissions inventories required for 
attainment demonstrations under this paragraph shall be one of the 3 
years used for designations or another technically appropriate inventory 
year if justified by the state in the plan submission.
    (4) The control strategies modeled as part of a Serious area 
attainment demonstration shall be consistent with the control strategies 
required pursuant to Sec. 51.1003 and Sec. 51.1010.
    (5) Required timeframe for obtaining emissions reductions. For each 
Serious nonattainment area, the attainment plan must provide for 
implementation of all control measures needed for attainment as 
expeditiously as practicable. All control measures must be implemented 
no later than the beginning of the year containing the applicable 
attainment date, notwithstanding BACM implementation deadline 
requirements in Sec. 51.1010.



Sec. 51.1012  Reasonable further progress (RFP) requirements.

    (a) Each attainment plan for a PM2.5 nonattainment area 
shall include an RFP plan that demonstrates that sources in the area 
will achieve such annual incremental reductions in emissions of direct 
PM2.5 and PM2.5 plan precursors as are necessary 
to ensure attainment of the applicable PM2.5 NAAQS as 
expeditiously as practicable. The RFP plan shall include all of the 
following:
    (1) A schedule describing the implementation of control measures 
during each year of the applicable attainment plan. Control measures for 
Moderate area attainment plans are required in Sec. 51.1009, and 
control measures for Serious area attainment plans are required in Sec. 
51.1010.
    (2) RFP projected emissions for direct PM2.5 and all 
PM2.5 plan precursors for each applicable milestone year, 
based on the anticipated implementation schedule for control measures 
required in paragraph (a)(1) of this section. For purposes of 
establishing motor vehicle emissions budgets for transportation 
conformity purposes (as required in 40 CFR part 93) for a 
PM2.5 nonattainment area, the state shall include in its RFP 
submission an inventory of on-road mobile source emissions in the 
nonattainment area for each milestone year.

[[Page 418]]

    (3) An analysis that presents the schedule of control measures and 
estimated emissions changes to be achieved by each milestone year, and 
that demonstrates that the control strategy will achieve reasonable 
progress toward attainment between the applicable base year and the 
attainment year. The analysis shall rely on information from the base 
year inventory for the nonattainment area required in Sec. 
51.1008(a)(1) and the attainment projected inventory for the 
nonattainment area required in Sec. 51.1008(a)(2), in addition to the 
RFP projected emissions required in paragraph (a)(2) of this section.
    (4) An analysis that demonstrates that by the end of the calendar 
year for each milestone date for the area determined in accordance with 
Sec. 51.1013(a), pollutant emissions will be at levels that reflect 
either generally linear progress or stepwise progress in reducing 
emissions on an annual basis between the base year and the attainment 
year. A demonstration of stepwise progress must be accompanied by 
appropriate justification for the selected implementation schedule.
    (5) At the state's election, an analysis that identifies air quality 
targets associated with the RFP projected emissions identified for the 
milestone years at the design value monitor locations.
    (b) For a multi-state or multi-jurisdictional nonattainment area, 
the RFP plans for each state represented in the nonattainment area shall 
demonstrate RFP on the basis of common multi-state inventories. The 
states or jurisdictions within which the area is located must provide a 
coordinated RFP plan. Each state in a multi-state nonattainment area 
must ensure that the sources within its boundaries comply with 
enforceable emission levels and other requirements that in combination 
with the reductions planned in other state(s) within the nonattainment 
area will provide for attainment as expeditiously as practicable and 
demonstrate RFP consistent with these regulations.



Sec. 51.1013  Quantitative milestone requirements.

    (a) Consistent with CAA section 189(c)(1), the state must submit in 
each attainment plan for a PM2.5 nonattainment area specific 
quantitative milestones that demonstrate reasonable further progress 
toward attainment of the applicable PM2.5 NAAQS in the area 
and that meet the following requirements:
    (1) Nonattainment areas initially classified as Moderate. (i) Except 
as provided in paragraph (a)(4) of this section, each attainment plan 
submittal for a Moderate PM2.5 nonattainment area shall 
contain quantitative milestones to be achieved no later than a milestone 
date of 4.5 years and 7.5 years from the date of designation of the 
area.
    (ii) The plan shall contain quantitative milestones to be achieved 
by the milestone dates specified in paragraph (a)(1)(i) of this section, 
as applicable, and that provide for objective evaluation of reasonable 
further progress toward timely attainment of the applicable 
PM2.5 NAAQS in the area. At a minimum, each quantitative 
milestone plan must include a milestone for tracking progress achieved 
in implementing the SIP control measures, including RACM and RACT, by 
each milestone date.
    (2) Nonattainment areas reclassified as Serious. (i) Except as 
provided in paragraph (a)(4) of this section, each attainment plan 
submission that demonstrates that a Serious PM2.5 
nonattainment area can attain a particular PM2.5 NAAQS by the 
end of the tenth calendar year following the effective date of 
designation of the area with the implementation of control measures as 
required under Sec. 51.1010(a) shall contain quantitative milestones to 
be achieved no later than milestone dates of 7.5 years and 10.5 years, 
respectively, from the date of designation of the area.
    (ii) Except as provided in paragraph (a)(4) of this section, each 
attainment plan submission that demonstrates that a Serious 
PM2.5 nonattainment area cannot practicably attain a 
particular PM2.5 NAAQS by the end of the tenth calendar year 
following the date

[[Page 419]]

of designation of the area with the implementation of control measures 
required under Sec. 51.1010(a) shall contain quantitative milestones to 
be achieved no later than milestone dates of 7.5 years, 10.5 years, and 
13.5 years from the date of designation of the area. If the attainment 
date is beyond 13.5 years from the date of designation of the area, such 
attainment plan shall also contain a quantitative milestones to be 
achieved no later than milestone dates of 16.5 years, respectively, from 
the date of designation of the area.
    (iii) The plan shall contain quantitative milestones to be achieved 
by the milestone dates specified in paragraphs (a)(2)(i) and (ii) of 
this section, as applicable, and that provide for objective evaluation 
of reasonable further progress toward timely attainment of the 
applicable PM2.5 NAAQS in the area. At a minimum, each 
quantitative milestone plan must include a milestone for tracking 
progress achieved in implementing SIP control measures, including BACM 
and BACT, by each milestone date.
    (3) Serious areas that fail to attain by the applicable Serious area 
attainment date. (i) Except as provided in paragraph (a)(4) of this 
section, each attainment plan submission for a Serious area that failed 
to attain a particular PM2.5 NAAQS by the applicable Serious 
area attainment date and is therefore subject to the requirements of CAA 
section 189(d) and Sec. 51.1003(c) shall contain quantitative 
milestones.
    (A) If the attainment plan is due prior to a date 13.5 years from 
designation of the area, then the plan shall contain milestones to be 
achieved by no later than a milestone date of 13.5 years from the date 
of designation of the area, and every 3 years thereafter, until the 
milestone date that falls within 3 years after the applicable attainment 
date.
    (B) If the attainment plan is due later than a date 13.5 years from 
designation of the area, then the plan shall contain milestones to be 
achieved by no later than a milestone date of 16.5 years from the date 
of designation of the area, and every 3 years thereafter, until the 
milestone date that falls within 3 years after the applicable attainment 
date.
    (ii) The plan shall contain quantitative milestones to be achieved 
by the milestone dates for the area, and that provide for objective 
evaluation of reasonable further progress toward timely attainment of 
the applicable PM2.5 NAAQS in the area. At a minimum, each 
quantitative milestone plan must include a milestone for tracking 
progress achieved in implementing the SIP control measures by each 
milestone date.
    (4) Each attainment plan submission for an area designated 
nonattainment for the 1997 and/or 2006 PM2.5 NAAQS before 
January 15, 2015, shall contain quantitative milestones to be achieved 
no later than 3 years after December 31, 2014, and every 3 years 
thereafter until the milestone date that falls within 3 years after the 
applicable attainment date.
    (b) Not later than 90 days after the date on which a milestone 
applicable to a PM2.5 nonattainment area occurs, each state 
in which all or part of such area is located shall submit to the 
Administrator a milestone report that contains all of the following:
    (1) A certification by the Governor or Governor's designee that the 
SIP control strategy is being implemented consistent with the RFP plan, 
as described in the applicable attainment plan;
    (2) Technical support, including calculations, sufficient to 
document completion statistics for appropriate milestones and to 
demonstrate that the quantitative milestones have been satisfied and how 
the emissions reductions achieved to date compare to those required or 
scheduled to meet RFP; and,
    (3) A discussion of whether the area will attain the applicable 
PM2.5 NAAQS by the projected attainment date for the area.
    (c) If a state fails to submit a milestone report by the date 
specified in paragraph (b) of this section, the Administrator shall 
require the state to submit, within 9 months after such failure, a plan 
revision that assures that the area will achieve the next milestone or 
attain the applicable NAAQS by the applicable date, whichever is 
earlier. If the Administrator determines that an area has not met any 
applicable milestone by the milestone

[[Page 420]]

date, the state shall submit, within 9 months after such determination, 
a plan revision that assures that the area will achieve the next 
milestone or attain the applicable NAAQS by the applicable date, 
whichever is earlier.



Sec. 51.1014  Contingency measure requirements.

    (a) The state must include as part of each attainment plan submitted 
under this subpart for a PM2.5 nonattainment area specific 
contingency measures that shall take effect with minimal further action 
by the state or the EPA following a determination by the Administrator 
that the area has failed:
    (1) To meet any RFP requirement in an attainment plan approved in 
accordance with Sec. 51.1012;
    (2) To meet any quantitative milestone in an attainment plan 
approved in accordance with Sec. 51.1013;
    (3) To submit a quantitative milestone report required under Sec. 
51.1013(b); or,
    (4) To attain the applicable PM2.5 NAAQS by the 
applicable attainment date.
    (b) The contingency measures adopted as part of a PM2.5 
attainment plan shall meet all of the following requirements:
    (1) The contingency measures shall consist of control measures that 
are not otherwise included in the control strategy or that achieve 
emissions reductions not otherwise relied upon in the control strategy 
for the area; and,
    (2) Each contingency measure shall specify the timeframe within 
which its requirements become effective following a determination by the 
Administrator under paragraph (a) of this section.
    (c) The attainment plan submission shall contain a description of 
the specific trigger mechanisms for the contingency measures and specify 
a schedule for implementation.



Sec. 51.1015  Clean data requirements.

    (a) Nonattainment areas initially classified as Moderate. Upon a 
determination by the EPA that a Moderate PM2.5 nonattainment 
area has attained the PM2.5 NAAQS, the requirements for the 
state to submit an attainment demonstration, provisions demonstrating 
that reasonably available control measures (including reasonably 
available control technology for stationary sources) shall be 
implemented no later than 4 years following the date of designation of 
the area, reasonable further progress plan, quantitative milestones and 
quantitative milestone reports, and contingency measures for the area 
shall be suspended until such time as:
    (1) The area is redesignated to attainment, after which such 
requirements are permanently discharged; or,
    (2) The EPA determines that the area has re-violated the 
PM2.5 NAAQS, at which time the state shall submit such 
attainment plan elements for the Moderate nonattainment area by a future 
date to be determined by the EPA and announced through publication in 
the Federal Register at the time EPA determines the area is violating 
the PM2.5 NAAQS.
    (b) Nonattainment areas reclassified as Serious. Upon a 
determination by the EPA that a Serious PM2.5 nonattainment 
area has attained the PM2.5 NAAQS, the requirements for the 
state to submit an attainment demonstration, reasonable further progress 
plan, quantitative milestones and quantitative milestone reports, and 
contingency measures for the area shall be suspended until such time as:
    (1) The area is redesignated to attainment, after which such 
requirements are permanently discharged; or,
    (2) The EPA determines that the area has re-violated the 
PM2.5 NAAQS, at which time the state shall submit such 
attainment plan elements for the Serious nonattainment area by a future 
date to be determined by the EPA and announced through publication in 
the Federal Register at the time the EPA determines the area is 
violating the PM2.5 NAAQS.



Sec. 51.1016  Continued applicability of the FIP and SIP requirements
pertaining to interstate transport under CAA section 110(a)(2)(D)(i)
and (ii) after revocation of the 1997 primary annual PM2.5 NAAQS.
          

    All control requirements associated with a FIP or approved SIP in 
effect for an area pursuant to obligations arising from CAA section 
110(a)(2)(D)(i) and (ii) as of October 24, 2016, such as the CAIR or the 
CSAPR, shall continue

[[Page 421]]

to apply after revocation of the 1997 primary annual PM2.5 
NAAQS. Control requirements associated with a FIP or approved into the 
SIP pursuant to obligations arising from CAA section 110(a)(2)(D)(i) and 
(ii), including 40 CFR 51.123, 51.124, 52.35, 52.36, 52.38 and 52.39, 
may be modified by the state only if the requirements of Sec. 51.123, 
51.124, 52.35, 52.36, 52.38 and 52.39, including statewide annual 
SO2 and annual NOX emission budgets, continue to 
be in effect. Any such modification must meet the requirements of CAA 
section 110(l).



  Subpart AA_Provisions for Implementation of the 2008 Ozone National 
                      Ambient Air Quality Standards

    Source: 77 FR 30170, May 21, 2012, unless otherwise noted.



Sec. 51.1100  Definitions.

    The following definitions apply for purposes of this subpart. Any 
term not defined herein shall have the meaning as defined in 40 CFR 
51.100.
    (a) 1-hour NAAQS means the 1-hour primary and secondary ozone 
national ambient air quality standards codified at 40 CFR 50.9.
    (b) 1997 NAAQS means the 1997 8-hour primary and secondary ozone 
national ambient air quality standards codified at 40 CFR 50.10.
    (c) 2008 NAAQS means the 2008 8-hour primary and secondary ozone 
NAAQS codified at 40 CFR 50.15.
    (d) 1-hour ozone design value is the 1-hour ozone concentration 
calculated according to 40 CFR part 50, appendix H and the 
interpretation methodology issued by the Administrator most recently 
before the date of the enactment of the CAA Amendments of 1990.
    (e) 8-hour ozone design value is the 8-hour ozone concentration 
calculated according to 40 CFR part 50, appendix P.
    (f) CAA means the Clean Air Act as codified at 42 U.S.C. 7401--7671q 
(2010).
    (g) Attainment area means, unless otherwise indicated, an area 
designated as either attainment, unclassifiable, or attainment/
unclassifiable.
    (h) Attainment year ozone season shall mean the ozone season 
immediately preceding a nonattainment area's maximum attainment date.
    (i) Designation for the 2008 NAAQS shall mean the effective date of 
the designation for an area for the 2008 NAAQS.
    (j) Higher classification/lower classification. For purposes of 
determining whether a classification is higher or lower, classifications 
under subpart 2 of part D of title I of the CAA are ranked from lowest 
to highest as follows: Marginal; Moderate; Serious; Severe; and Extreme.
    (k) Initially designated means the first designation that becomes 
effective for an area for the 2008 NAAQS and does not include a 
redesignation to attainment or nonattainment for the 2008 NAAQS.
    (l) Maintenance area means an area that was designated nonattainment 
for a specific NAAQS and was redesignated to attainment for that NAAQS 
subject to a maintenance plan as required by CAA section 175A.
    (m) Nitrogen Oxides (NOX) means the sum of nitric oxide 
and nitrogen dioxide in the flue gas or emission point, collectively 
expressed as nitrogen dioxide.
    (n) Ozone season means for each state, the ozone monitoring season 
as defined in 40 CFR part 58, appendix D, section 4.1(i) for that state.
    (o) Applicable requirements for an area for anti-backsliding 
purposes means the following requirements, to the extent such 
requirements apply to the area pursuant to its classification under CAA 
section 181(a)(1) for the 1-hour NAAQS or 40 CFR 51.902 for the 1997 
ozone NAAQS at the time of revocation of the 1997 ozone NAAQS:
    (1) Reasonably available control technology (RACT) under CAA 
sections 172(c)(1) and 182(b)(2).
    (2) Vehicle inspection and maintenance programs (I/M) under CAA 
sections 182(b)(4) and 182(c)(3).
    (3) Major source applicability thresholds for purposes of RACT under 
CAA sections 172(c)(2), 182(b), 182(c), 182(d), and 182(e).
    (4) Reductions to achieve Reasonable Further Progress (RFP) under 
CAA sections172(c)(2), 182(b)(1)(A), and 182(c)(2)(B).

[[Page 422]]

    (5) Clean fuels fleet program under CAA section183(c)(4).
    (6) Clean fuels for boilers under CAA section 182(e)(3).
    (7) Transportation Control Measures (TCMs) during heavy traffic 
hours as specified under CAA section 182(e)(4).
    (8) Enhanced (ambient) monitoring under CAA section 182(c)(1).
    (9) Transportation controls under CAA section 182(c)(5).
    (10) Vehicle miles traveled provisions of CAA section 182(d)(1).
    (11) NOX requirements under CAA section 182(f).
    (12) Attainment demonstration requirements under CAA sections 
172(c)(4), 182(b)(1)(A), and 182(c)(2).
    (13) Nonattainment contingency measures required under CAA sections 
172(c)(9) and 182(c)(9) for failure to attain the 1-hour or 1997 ozone 
NAAQS by the applicable attainment date or to make reasonable further 
progress toward attainment of the 1-hour or 1997 ozone NAAQS.
    (14) Nonattainment NSR major source thresholds and offset ratios 
under CAA sections 172(a)(5) and 182(a)(2).
    (15) Penalty fee program requirements for Severe and Extreme Areas 
under CAA section 185.
    (16) Contingency measures associated with areas utilizing CAA 
section 182(e)(5).
    (17) Reasonably available control measures (RACM) requirements under 
CAA section 172(c)(1).
    (p) CSAPR means the Cross State Air Pollution Rule codified at 40 
CFR 52.38 and part 97.
    (q) CAIR means the Clean Air Interstate Rule codified at 40 CFR 
51.123, 52.35 and part 95.
    (r) NOX SIP Call means the rules codified at 40 CFR 51.121 and 
51.122.
    (s) Ozone transport region (OTR) means the area established by CAA 
section 184(a) or any other area established by the Administrator 
pursuant to CAA section 176A for purposes of ozone.
    (t) Reasonable further progress (RFP) means both the emissions 
reductions required under CAA section 172(c)(2) which EPA interprets to 
be an average 3 percent per year emissions reductions of either VOC or 
NOX and CAA sections 182(c)(2)(B) and (c)(2)(C) and the 15 
percent reductions over the first six years of the plan and the 
following three percent per year average under Sec. 51.1110.
    (u) Rate-of-progress (ROP) means the 15 percent progress reductions 
in VOC emissions over the first 6 years required under CAA section 
182(b)(1).
    (v) Revocation of the 1-hour NAAQS means the time at which the 1-
hour NAAQS no longer apply to an area pursuant to 40 CFR 50.9(b).
    (w) Revocation of the 1997 ozone NAAQS means the time at which the 
1997 8-hour NAAQS no longer apply to an area pursuant to 40 CFR 
50.10(c).
    (x) Subpart 1 means subpart 1 of part D of title I of the CAA.
    (y) Subpart 2 means subpart 2 of part D of title I of the CAA.
    (z) I/M refers to the inspection and maintenance programs for in-use 
vehicles required under the 1990 CAA Amendments and defined by subpart S 
of 40 CFR part 51.
    (aa) An area ``Designated nonattainment for the 1-hour ozone NAAQS'' 
means, for purposes of 40 CFR 51.1105, an area that is subject to 
applicable 1-hour ozone NAAQS anti-backsliding requirements at the time 
of revocation of the 1997 ozone NAAQS.
    (bb) Base year inventory for the nonattainment area means a 
comprehensive, accurate, current inventory of actual emissions from 
sources of VOC and NOX emitted within the boundaries of the 
nonattainment area as required by CAA section 182(a)(1).
    (cc) Ozone season day emissions means an average day's emissions for 
a typical ozone season work weekday. The state shall select, subject to 
EPA approval, the particular month(s) in the ozone season and the day(s) 
in the work week to be represented, considering the conditions assumed 
in the development of RFP plans and/or emissions budgets for 
transportation conformity.

[77 FR 30170, May 21, 2012, as amended at 80 FR 12312, Mar. 6, 2015]



Sec. 51.1101  Applicability of part 51.

    The provisions in subparts A-X of part 51 apply to areas for 
purposes of the 2008 NAAQS to the extent they are not inconsistent with 
the provisions of this subpart.

[[Page 423]]



Sec. 51.1102  Classification and nonattainment area planning provisions.

    An area designated nonattainment for the 2008 ozone NAAQS will be 
classified in accordance with CAA section 181, as interpreted in Sec. 
51.1103(a), and will be subject to the requirements of subpart 2 of part 
D of title I of the CAA that apply for that classification.



Sec. 51.1103  Application of classification and attainment date 
provisions in CAA section 181 to areas subject to Sec. 51.1102.

    (a) In accordance with CAA section 181(a)(1), each area designated 
nonattainment for the 2008 ozone NAAQS shall be classified by operation 
of law at the time of designation. The classification shall be based on 
the 8-hour design value for the area at the time of designation, in 
accordance with Table 1 below. A state may request a higher or lower 
classification as provided in paragraphs (b) and (c) of this section. 
For each area classified under this section, the attainment date for the 
2008 NAAQS shall be as expeditious as practicable but not later than the 
date provided in Table 1 as follows:

 Table 1--Classifications and Attainment Dates for 2008 8-Hour Ozone NAAQS (0.075 PPM) for Areas Subject to CFR
                                                 Section 51.1102
----------------------------------------------------------------------------------------------------------------
                                                                                                Primary standard
                                                                                                attainment date
                                                                                8-hour design   (years after the
                 Area class                                                      value (ppm    effective date of
                                                                                   ozone)       designation for
                                                                                                  2008 primary
                                                                                                     NAAQS)
----------------------------------------------------------------------------------------------------------------
Marginal....................................  from...........................           0.076                  3
                                              up to*.........................           0.086
Moderate....................................  from...........................           0.086                  6
                                              up to*.........................           0.100
Serious.....................................  from...........................           0.100                  9
                                              up to*.........................           0.113
Severe-15...................................  from...........................           0.113                 15
                                              up to*.........................           0.119
Severe-17...................................  from...........................           0.119                 17
                                              up to*.........................           0.175
Extreme.....................................  equal to or above..............           0.175                 20
----------------------------------------------------------------------------------------------------------------
* But not including

    (b) A state may request, and the Administrator must approve, a 
higher classification for any reason in accordance with CAA section 
181(b)(3).
    (c) A state may request, and the Administrator may in the 
Administrator's discretion approve, a higher or lower classification in 
accordance with CAA section 181(a)(4).
    (d) The following nonattainment areas are reclassified for the 2008 
ozone NAAQS as follows: Serious--Ventura County, CA; Severe--Los 
Angeles-San Bernardino Counties (West Mojave Desert), Riverside County 
(Coachella Valley), and Sacramento Metro, CA; Extreme--Los Angeles-South 
Coast Air Basin, and San Joaquin Valley, CA.

[77 FR 30170, May 21, 2012, as amended at 80 FR 12313, Mar. 6, 2015]



Sec. 51.1104  [Reserved]



Sec. 51.1105  Transition from the 1997 ozone NAAQS to the 2008 ozone
NAAQS and anti-backsliding.

    (a) Requirements that continue to apply after revocation of the 1997 
ozone NAAQS--(1) 2008 ozone NAAQS nonattainment and 1997 ozone NAAQS 
nonattainment. The following requirements apply to an area designated 
nonattainment for the 2008 ozone NAAQS and also designated nonattainment 
for the 1997 ozone NAAQS, or nonattainment for both the 1997 and 1-hour 
ozone NAAQS, at the time of revocation of the respective ozone NAAQS: 
The area remains subject to the obligation to adopt and implement the 
applicable requirements of Sec. 51.1100(o), for any ozone NAAQS for 
which it was designated

[[Page 424]]

nonattainment at the time of revocation, in accordance with its 
classification for that NAAQS at the time of that revocation, except as 
provided in paragraph (b) of this section.
    (2) 2008 ozone NAAQS nonattainment and 1997 ozone NAAQS maintenance. 
For an area designated nonattainment for the 2008 ozone NAAQS that was 
redesignated to attainment for the 1997 ozone NAAQS prior to April 6, 
2015 (hereinafter a ``maintenance area'') the SIP, including the 
maintenance plan, is considered to satisfy the applicable requirements 
of 40 CFR 51.1100(o) for the revoked NAAQS. The measures in the SIP and 
maintenance plan shall continue to be implemented in accordance with the 
terms in the SIP. Any measures associated with applicable requirements 
that were shifted to contingency measures prior to April 6, 2015 may 
remain in that form. After April 6, 2015, and to the extent consistent 
with any SIP for the 2008 ozone NAAQS and with CAA sections 110(l) and 
193, the state may request that obligations under the applicable 
requirements of Sec. 51.1100(o) be shifted to the SIP's list of 
maintenance plan contingency measures for the area.
    (3) 2008 ozone NAAQS attainment and 1997 ozone NAAQS nonattainment. 
For an area designated attainment for the 2008 ozone NAAQS, and 
designated nonattainment for the 1997 ozone NAAQS as of April 6, 2015 or 
for both the 1997 and the 1-hour ozone NAAQS as of the respective dates 
of their revocations, the area is no longer subject to nonattainment NSR 
and the state may at any time request that the nonattainment NSR 
provisions applicable to the area be removed from the SIP. The state may 
request, consistent with CAA sections 110(l) and 193, that SIP measures 
adopted to satisfy other applicable requirements of Sec. 51.1100(o) be 
shifted to the SIP's list of maintenance plan contingency measures for 
the area. The area's approved PSD SIP shall be considered to satisfy the 
state's obligations with respect to the area's maintenance of the 2008 
ozone NAAQS pursuant to CAA section 110(a)(1).
    (4) 2008 ozone NAAQS attainment and 1997 ozone NAAQS maintenance. An 
area designated attainment for the 2008 ozone NAAQS with an approved CAA 
section 175A maintenance plan for the 1997 ozone NAAQS is considered to 
satisfy the applicable requirements of 40 CFR 51.1100(o) through 
implementation of the SIP and maintenance plan provisions for the area. 
After April 6, 2015, and to the extent consistent with CAA sections 
110(l) and 193, the state may request that obligations under the 
applicable requirements of 40 CFR 51.1100(o) be shifted to the list of 
maintenance plan contingency measures for the area. For an area that is 
initially designated attainment for the 2008 ozone NAAQS and which has 
been redesignated to attainment for the 1997 ozone NAAQS with an 
approved CAA section 175A maintenance plan and an approved PSD SIP, the 
area's approved maintenance plan and the state's approved PSD SIP for 
the area are considered to satisfy the state's obligations with respect 
to the area's maintenance of the 2008 ozone NAAQS pursuant to CAA 
section 110(a)(1).
    (b) Effect of Redesignation or Redesignation Substitute. (1) An area 
remains subject to the anti-backsliding obligations for a revoked NAAQS 
under paragraphs (a)(1) and (2) of this section until either EPA 
approves a redesignation to attainment for the area for the 2008 ozone 
NAAQS; or EPA approves a demonstration for the area in a redesignation 
substitute procedure for a revoked NAAQS. Under this redesignation 
substitute procedure for a revoked NAAQS, and for this limited anti-
backsliding purpose, the demonstration must show that the area has 
attained that revoked NAAQS due to permanent and enforceable emission 
reductions and that the area will maintain that revoked NAAQS for 10 
years from the date of EPA's approval of this showing.
    (2) If EPA, after notice-and-comment rulemaking, approves a 
redesignation to attainment, the state may request that provisions for 
nonattainment NSR be removed from the SIP, and that other anti-
backsliding obligations be shifted to contingency measures provided that 
such action is consistent with CAA sections 110(l) and 193. If EPA, 
after notice and comment rulemaking, approves a redesignation substitute 
for a revoked NAAQS, the state

[[Page 425]]

may request that provisions for nonattainment NSR for that revoked NAAQS 
be removed, and that other anti-backsliding obligations for that revoked 
NAAQS be shifted to contingency measures provided that such action is 
consistent with CAA sections 110(l) and 193.
    (c) Portions of an area designated nonattainment or attainment for 
the 2008 ozone NAAQS that remain subject to the obligations identified 
in paragraph (a) of this section. Only that portion of the designated 
nonattainment or attainment area for the 2008 ozone NAAQS that was 
required to adopt the applicable requirements in Sec. 51.1100(o) for 
purposes of the 1-hour or 1997 ozone NAAQS is subject to the obligations 
identified in paragraph (a) of this section. Subpart C of 40 CFR part 81 
identifies the areas designated nonattainment and associated area 
boundaries for the 1997 ozone NAAQS at the time of revocation. Areas 
that are designated nonattainment for the 1997 ozone NAAQS at the time 
of designation for the 2008 ozone NAAQS may be redesignated to 
attainment prior to the effective date of revocation of that ozone 
NAAQS.
    (d) Obligations under the 1997 ozone NAAQS that no longer apply 
after revocation of the 1997 ozone NAAQS--(1) Second 10-year Maintenance 
plans. As of April 6, 2015, an area with an approved 1997 ozone NAAQS 
maintenance plan under CAA section 175A is not required to submit a 
second 10-year maintenance plan for the 1997 ozone NAAQS 8 years after 
approval of the initial 1997 ozone NAAQS maintenance plan.
    (2) Determinations of failure to attain the 1997 and/or 1-hour 
NAAQS. (i) As of April 6, 2015, the EPA is no longer obligated to 
determine pursuant to CAA section 181(b)(2) or section 179(c) whether an 
area attained the 1997 ozone NAAQS by that area's attainment date for 
the 1997 ozone NAAQS.
    (ii) As of April 6, 2015, the EPA is no longer obligated to 
reclassify an area to a higher classification for the 1997 ozone NAAQS 
based upon a determination that the area failed to attain the 1997 ozone 
NAAQS by the area's attainment date for the 1997 ozone NAAQS.
    (iii) For the revoked 1-hour and 1997 ozone NAAQS, the EPA is 
required to determine whether an area attained the 1-hour or 1997 ozone 
NAAQS by the area's attainment date solely for anti-backsliding purposes 
to address an applicable requirement for nonattainment contingency 
measures and CAA section 185 fee programs. In making such a 
determination, the EPA may consider and apply the provisions of CAA 
section 181(a)(5) and former 40 CFR 51.907 in interpreting whether a 1-
year extension of the attainment date is applicable under CAA section 
172(a)(2)(C).
    (e) Continued applicability of the FIP and SIP requirements 
pertaining to interstate transport under CAA section 110(a)(2)(D)(i) and 
(ii) after revocation of the 1997 ozone NAAQS. All control requirements 
associated with a FIP or approved SIP in effect for an area as of April 
6, 2015, such as the NOX SIP Call, the CAIR, or the CSAPR 
shall continue to apply after revocation of the 1997 ozone NAAQS. 
Control requirements approved into the SIP pursuant to obligations 
arising from CAA section 110(a)(2)(D)(i) and (ii), including 40 CFR 
51.121, 51.122, 51.123 and 51.124, may be modified by the state only if 
the requirements of Sec. Sec. 51.121, 51.122, 51.123 and 51.124, 
including statewide NOX emission budgets continue to be in 
effect. Any such modification must meet the requirements of CAA section 
110(l).
    (f) New source review. An area designated nonattainment for the 2008 
ozone NAAQS and designated nonattainment for the 1997 ozone NAAQS on 
April 6, 2015 remains subject to the obligation to adopt and implement 
the major source threshold and offset requirements for nonattainment NSR 
that apply or applied to the area pursuant to CAA sections 172(c)(5), 
173 and 182 based on the highest of: (i) The area's classification under 
CAA section 181(a)(1) for the 1-hour NAAQS as of the effective date of 
revocation of the 1-hour ozone NAAQS; (ii) the area's classification 
under 40 CFR 51.903 for the 1997 ozone NAAQS as of the date a permit is 
issued or as of April 6, 2015, whichever is earlier; and (iii) the 
area's classification under Sec. 51.1103 for the 2008 ozone NAAQS. Upon 
removal of nonattainment NSR obligations for a revoked NAAQS under Sec. 
51.1105(b), the state remains subject to the obligation

[[Page 426]]

to adopt and implement the major source threshold and offset 
requirements for nonattainment NSR that apply or applied to the area for 
the remaining applicable NAAQS consistent with this paragraph.

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1106  Redesignation to nonattainment following initial
designations.

    For any area that is initially designated attainment for the 2008 
ozone NAAQS and that is subsequently redesignated to nonattainment for 
the 2008 ozone NAAQS, any absolute, fixed date applicable in connection 
with the requirements of this part other than an attainment date is 
extended by a period of time equal to the length of time between the 
effective date of the initial designation for the 2008 ozone NAAQS and 
the effective date of redesignation, except as otherwise provided in 
this subpart. The maximum attainment date for a redesignated area would 
be based on the area's classification, consistent with Table 1 in Sec. 
51.1103.

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1107  Determining eligibility for 1-year attainment date
extensions for the 2008 ozone NAAQS under CAA section 181(a)(5).

    (a) A nonattainment area will meet the requirement of CAA section 
181(a)(5)(B) pertaining to 1-year extensions of the attainment date if:
    (1) For the first 1-year extension, the area's 4th highest daily 
maximum 8 hour average in the attainment year is 0.075 ppm or less.
    (2) For the second 1-year extension, the area's 4th highest daily 
maximum 8 hour value, averaged over both the original attainment year 
and the first extension year, is 0.075 ppm or less.
    (b) For purposes of paragraph (a) of this section, the area's 4th 
highest daily maximum 8 hour average for a year shall be from the 
monitor with the highest 4th highest daily maximum 8 hour average for 
that year of all the monitors that represent that area.

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1108  Modeling and attainment demonstration requirements.

    (a) An area classified as Moderate under Sec. 51.1103(a) shall be 
subject to the attainment demonstration requirement applicable for that 
classification under CAA section 182(b), and such demonstration is due 
no later than 36 months after the effective date of the area's 
designation for the 2008 ozone NAAQS.
    (b) An area classified as Serious or higher under Sec. 51.1103(a) 
shall be subject to the attainment demonstration requirement applicable 
for that classification under CAA section 182(c), and such demonstration 
is due no later than 48 months after the effective date of the area's 
designation for the 2008 ozone NAAQS.
    (c) Attainment demonstration criteria. An attainment demonstration 
due pursuant to paragraph (a) or (b) of this section must meet the 
requirements of Sec. 51.112; the adequacy of an attainment 
demonstration shall be demonstrated by means of a photochemical grid 
model or any other analytical method determined by the Administrator, in 
the Administrator's discretion, to be at least as effective.
    (d) Implementation of control measures. For each nonattainment area, 
the state must provide for implementation of all control measures needed 
for attainment no later than the beginning of the attainment year ozone 
season.

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1109  [Reserved]



Sec. 51.1110  Requirements for reasonable further progress (RFP).

    (a) RFP for nonattainment areas classified pursuant to Sec. 
51.1103. The RFP requirements specified in CAA section 182 for that 
area's classification shall apply.
    (1) Submission deadline. For each area classified as Moderate or 
higher pursuant to Sec. 51.1103, the state shall submit a SIP revision 
no later than 36 months after the effective date of designation as 
nonattainment for the 2008 ozone NAAQS that provides for RFP as 
described in paragraphs (a)(2) through (4) of this section.
    (2) RFP requirements for areas with an approved 1-hour or 1997 ozone 
NAAQS 15

[[Page 427]]

percent VOC ROP plan. An area classified as Moderate or higher that has 
the same boundaries as an area, or is entirely composed of several areas 
or portions of areas, for which EPA fully approved a 15 percent plan for 
the 1-hour or 1997 ozone NAAQS is considered to have met the 
requirements of CAA section 182(b)(1) for the 2008 ozone NAAQS and 
instead:
    (i) If classified as Moderate or higher, the area is subject to the 
RFP requirements under CAA section 172(c)(2) and shall submit a SIP 
revision that:
    (A) Provides for a 15 percent emission reduction from the baseline 
year within 6 years after the baseline year;
    (B) Provides for an additional emissions reduction of 3 percent per 
year from the end of the first 6 years up to the beginning of the 
attainment year if a baseline year earlier than 2011 is used; and
    (C) Relies on either NOX or VOC emissions reductions (or 
a combination) to meet the requirements of paragraphs (a)(2)(i)(A) and 
(B) of this section. Use of NOX emissions reductions must 
meet the criteria in CAA section 182(c)(2)(C).
    (ii) If classified as Serious or higher, the area is also subject to 
RFP under CAA section 182(c)(2)(B) and shall submit a SIP revision no 
later than 48 months after the effective date of designation providing 
for an average emissions reduction of 3 percent per year:
    (A) For all remaining 3-year periods after the first 6-year period 
until the year of the area's attainment date; and
    (B) That relies on either NOX or VOC emissions reductions 
(or a combination) to meet the requirements of paragraphs (a)(2)(ii)(A) 
and (B) of this section. Use of NOX emissions reductions must 
meet the criteria in CAA section 182(c)(2)(C).
    (3) RFP requirements for areas for which an approved 15 percent VOC 
ROP plan for the 1-hour or 1997 ozone NAAQS exists for only a portion of 
the area. An area that contains one or more portions for which EPA fully 
approved a 15 percent VOC ROP plan for the 1-hour or 1997 ozone NAAQS 
(as well as areas for which EPA has not fully approved a 15 percent plan 
for either the 1-hour or 1997 ozone NAAQS) shall meet the requirements 
of either paragraph (a)(3)(i) or (ii) of this section.
    (i) The state shall not distinguish between the portion of the area 
with a previously approved 15 percent ROP plan and the portion of the 
area without such a plan, and shall meet the requirements of (a)(4) of 
this section for the entire nonattainment area.
    (ii) The state shall treat the area as two parts, each with a 
separate RFP target as follows:
    (A) For the portion of the area without an approved 15 percent VOC 
ROP plan for the 1-hour or 1997 ozone NAAQS, the state shall submit a 
SIP revision as required under paragraph (a)(4) of this section.
    (B) For the portion of the area with an approved 15 percent VOC ROP 
plan for the 1-hour or 1997 ozone NAAQS, the state shall submit a SIP as 
required under paragraph (a)(2) of this section.
    (4) ROP Requirements for areas without an approved 1-hour or 1997 
ozone NAAQS 15 percent VOC ROP plan. (i) For each area, the state shall 
submit a SIP revision consistent with CAA section 182(b)(1). The 6-year 
period referenced in CAA section 182(b)(1) shall begin January 1 of the 
year following the year used for the baseline emissions inventory.
    (ii) For Moderate areas, the plan must provide for an additional 3 
percent per year reduction from the end of the first 6 years up to the 
beginning of the attainment year if a baseline year from 2008 to 2010 is 
used.
    (iii) For each area classified as Serious or higher, the state shall 
submit a SIP revision consistent with CAA section 182(c)(2)(B). The 
final increment of progress must be achieved no later than the 
attainment date for the area.
    (5) Creditability of emission control measures for RFP plans. Except 
as specifically provided in CAA section 182(b)(1)(C) and (D), CAA 
section 182(c)(2)(B), and 40 CFR 51.1110(a)(6), all emission reductions 
from SIP-approved or federally promulgated measures that occur after the 
baseline emissions inventory year are creditable for purposes of the RFP 
requirements in this section, provided the reductions meet

[[Page 428]]

the requirements for creditability, including the need to be 
enforceable, permanent, quantifiable, and surplus.
    (6) Creditability of out-of-area emissions reductions. For each area 
classified as Moderate or higher pursuant to Sec. 51.1103, in addition 
to the restrictions on the creditability of emission control measures 
listed in Sec. 51.1110(a)(5), creditable emission reductions for fixed 
percentage reduction RFP must be obtained from sources within the 
nonattainment area.
    (7) Calculation of non-creditable emissions reductions. The 
following four categories of control measures listed in CAA section 
182(b)(1)(D) are no longer required to be calculated for exclusion in 
RFP analyses because the Administrator has determined that due to the 
passage of time the effect of these exclusions would be de minimis:
    (i) Measures related to motor vehicle exhaust or evaporative 
emissions promulgated by January 1, 1990;
    (ii) Regulations concerning Reid vapor pressure promulgated by 
November 15, 1990;
    (iii) Measures to correct previous RACT requirements; and
    (iv) Measures required to correct previous I/M programs.
    (b) Baseline emissions inventory for RFP plans. For the RFP plans 
required under this section, at the time of designation for the 2008 
ozone NAAQS the baseline emissions inventory shall be the emissions 
inventory for the most recent calendar year for which a complete 
triennial inventory is required to be submitted to EPA under the 
provisions of subpart A of this part. States may use an alternative 
baseline emissions inventory provided the state demonstrates why it is 
appropriate to use the alternative baseline year, and provided that the 
year selected is between the years 2008 to 2012. All states associated 
with a multi-state nonattainment area must consult and agree on a single 
alternative baseline year. The emissions values included in the 
inventory required by this section shall be actual ozone season day 
emissions as defined by Sec. 51.1100(cc).

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1111  [Reserved]



Sec. 51.1112  Requirements for reasonably available control technology
(RACT) and reasonably available control measures (RACM).

    (a) RACT requirement for areas classified pursuant to Sec. 51.1103. 
(1) For each nonattainment area classified Moderate or higher, the state 
shall submit a SIP revision that meets the VOC and NOX RACT 
requirements in CAA sections 182(b)(2) and 182(f).
    (2) The state shall submit the RACT SIP for each area no later than 
24 months after the effective date of designation for the 2008 ozone 
NAAQS.
    (3) The state shall provide for implementation of RACT as 
expeditiously as practicable but no later than January 1 of the 5th year 
after the effective date of designation for the 2008 ozone NAAQS.
    (b) Determination of major stationary sources for applicability of 
RACT provisions. The amount of VOC and NOX emissions are to 
be considered separately for purposes of determining whether a source is 
a major stationary source as defined in CAA section 302.
    (c) Reasonably Available Control Measures (RACM) requirement. For 
each nonattainment area required to submit an attainment demonstration 
under Sec. 51.1108(a) and (b), the state shall submit with the 
attainment demonstration a SIP revision demonstrating that it has 
adopted all RACM necessary to demonstrate attainment as expeditiously as 
practicable and to meet any RFP requirements.

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1113  Section 182(f) NOX exemption provisions.

    (a) A person or a state may petition the Administrator for an 
exemption from NOX obligations under CAA section 182(f) for 
any area designated nonattainment for the 2008 ozone NAAQS and for any 
area in a CAA section 184 ozone transport region.
    (b) The petition must contain adequate documentation that the 
criteria in CAA section 182(f) are met.
    (c) A CAA section 182(f) NOX exemption granted for the 1-
hour or 1997 ozone NAAQS does not relieve the area from any 
NOX obligations under CAA

[[Page 429]]

section 182(f) for the 2008 ozone NAAQS.

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1114  New source review requirements.

    The requirements for nonattainment NSR for the ozone NAAQS are 
located in Sec. 51.165. For each nonattainment area, the state shall 
submit a nonattainment NSR plan or plan revision for the 2008 ozone 
NAAQS no later than 36 months after the effective date of the area's 
designation for the 2008 ozone NAAQS.

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1115  Emissions inventory requirements.

    (a) For each nonattainment area, the state shall submit a base year 
inventory as defined by Sec. 51.1100(bb) to meet the emissions 
inventory requirement of CAA section 182(a)(1). This inventory shall be 
submitted no later than 24 months after the effective date of 
designation. The inventory year shall be selected consistent with the 
baseline year for the RFP plan as required by Sec. 51.1110(b).
    (b) For each nonattainment area, the state shall submit a periodic 
emission inventory of emissions sources in the area to meet the 
requirement in CAA section 182(a)(3)(A). With the exception of the 
inventory year and timing of submittal, this inventory shall be 
consistent with the requirements of paragraph (a) of this section. Each 
periodic inventory shall be submitted no later than the end of each 3-
year period after the required submission of the base year inventory for 
the nonattainment area. This requirement shall apply until the area is 
redesignated to attainment.
    (c) The emissions values included in the inventories required by 
paragraphs (a) and (b) of this section shall be actual ozone season day 
emissions as defined by Sec. 51.1100(cc).
    (d) The state shall report emissions from point sources according to 
the point source emissions thresholds of the Air Emissions Reporting 
Requirements (AERR), 40 CFR part 51, subpart A.
    (e) The data elements in the emissions inventory shall be consistent 
with the detail required by 40 CFR part 51, subpart A. Since only 
emissions within the boundaries of the nonattainment area shall be 
included as defined by Sec. 51.1100(cc), this requirement shall apply 
to the emissions inventories required in this section instead of any 
total county requirements contained in 40 CFR part 51, subpart A.

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1116  Requirements for an Ozone Transport Region.

    (a) In general. CAA sections 176A and 184 apply for purposes of the 
2008 ozone NAAQS.
    (b) RACT requirements for certain portions of an Ozone Transport 
Region. (1) The state shall submit a SIP revision that meets the RACT 
requirements of CAA section 184(b)(2) for all portions of the state 
located in an ozone transport region.
    (2) The state shall submit the RACT revision no later than 24 months 
after designation for the 2008 ozone NAAQS and shall provide for 
implementation of RACT as expeditiously as practicable but no later than 
January 1 of the 5th year after designation for the 2008 ozone NAAQS.

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1117  Fee programs for Severe and Extreme nonattainment areas
that fail to attain.

    For each area classified as Severe or Extreme for the 2008 ozone 
NAAQS, the state shall submit a SIP revision within 10 years of the 
effective date of designation that meets the requirements of CAA section 
185.

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1118  Suspension of SIP planning requirements in nonattainment
areas that have air quality data that meet an ozone NAAQS.

    Upon a determination by EPA that an area designated nonattainment 
for the 2008 ozone NAAQS, or for any prior ozone NAAQS, has attained the 
relevant standard, the requirements for such area to submit attainment 
demonstrations and associated reasonably available control measures, 
reasonable

[[Page 430]]

further progress plans, contingency measures for failure to attain or 
make reasonable progress and other planning SIPs related to attainment 
of the 2008 ozone NAAQS, or for any prior NAAQS for which the 
determination has been made, shall be suspended until such time as: The 
area is redesignated to attainment for that NAAQS or a redesignation 
substitute is approved as appropriate, at which time the requirements no 
longer apply; or EPA determines that the area has violated that NAAQS, 
at which time the area is again required to submit such plans.

[80 FR 12314, Mar. 6, 2015]



Sec. 51.1119  Applicability.

    As of revocation of the 1997 ozone NAAQS on April 6, 2015, as set 
forth in Sec. 50.10(c), the provisions of subpart AA shall replace the 
provisions of subpart X, Sec. Sec. 51.900 to 51.918, which cease to 
apply except for Sec. 51.907 for the anti-backsliding purposes of Sec. 
51.1105(c)(2). See subpart X Sec. 51.919.

[80 FR 12314, Mar. 6, 2015]



  Subpart BB_Data Requirements for Characterizing Air Quality for the 
                      Primary SO2 NAAQS

    Source: 80 FR 51087, Aug. 21, 2015, unless otherwise noted.



Sec. 51.1200  Definitions.

    The following definitions apply for the purposes of this subpart. 
All terms not defined herein will have the meaning given them in Sec. 
51.100 or in the Clean Air Act (CAA). Air agency means the agency or 
organization responsible for air quality management within a state, 
local governmental jurisdiction, territory or area subject to tribal 
government. Annual SO2 emissions data means the quality-
assured annual SO2 emissions data for a stationary source. 
Such data may have been required to be reported to the EPA in accordance 
with an existing regulatory requirement (such as the Air Emissions 
Reporting Rule or the Acid Rain Program); however, annual SO2 
emissions data may be obtained or determined through other reliable 
means as well.
    Applicable source means a stationary source that is:
    (1) Not located in a designated nonattainment area, and
    (2) Has actual annual SO2 emissions data of 2,000 tons or 
more, or has been identified by an air agency or by the EPA Regional 
Administrator as requiring further air quality characterization. 2010 
SO2 NAAQS means the primary National Ambient Air Quality 
Standard for sulfur oxides (sulfur dioxide) as codified at 40 CFR 50.17, 
as effective August 23, 2010.



Sec. 51.1201  Purpose.

    The purpose of this subpart is to require air agencies to develop 
and submit air quality data characterizing maximum 1-hour ambient 
concentrations of SO2 across the United States through either 
ambient air quality monitoring or air quality modeling analysis at the 
air agency's election. These monitoring and modeling data may be used in 
future determinations by the EPA regarding areas' SO2 NAAQS 
attainment status, or for other actions designed to ensure attainment of 
the 2010 SO2 NAAQS and provide protection to the public from 
the short-term health effects associated with exposure to SO2 
concentrations that exceed the NAAQS.



Sec. 51.1202  Applicability.

    This subpart applies to any air agency in whose jurisdiction is 
located one or more applicable sources of SO2 emissions that 
have annual actual SO2 emissions of 2,000 tons or more; or in 
whose jurisdiction is located one or more sources of SO2 
emissions that have been identified by the air agency or by the EPA 
Regional Administrator as requiring further air quality 
characterization. For the purposes of this subpart, the subject air 
agency shall identify applicable sources of SO2 based on the 
most recently available annual SO2 emissions data for such 
sources.



Sec. 51.1203  Air agency requirements.

    (a) The air agency shall submit a list of applicable SO2 
sources identified pursuant to Sec. 51.1202 located in its jurisdiction 
to the EPA by January 15, 2016. This list may be revised by the Regional 
Administrator after review based on available SO2 emissions 
data.

[[Page 431]]

    (b) For each source area subject to requirements for air quality 
characterization, the air agency shall notify the EPA by July 1, 2016, 
whether it has chosen to characterize peak 1-hour SO2 
concentrations in such area through ambient air quality monitoring; 
characterize peak 1-hour SO2 concentrations in such area 
through air quality modeling techniques; or provide federally 
enforceable emission limitations by January 13, 2017 that limit 
emissions of applicable sources to less than 2,000 tpy, in accordance 
with paragraph (e) of this section, or provide documentation that the 
applicable source has permanently shut down. Emission limits in 
accordance with paragraph (e) of this section may be established in lieu 
of conducting monitoring or modeling unless, in the judgment of the air 
agency or the EPA Regional Administrator, the area warrants further air 
quality characterization even with the establishment of any new emission 
limit(s). If the air agency has chosen to establish requirements to 
limit emissions for applicable sources in an area, the notification from 
the air agency shall describe the requirements and emission limits the 
air agency intends to apply. For any area with multiple applicable 
sources, the air agency (or air agencies if a multi-state area) shall 
use the same technique (monitoring, modeling, or emissions limitation) 
for all applicable sources in the area. If multiple air agencies have 
applicable sources in an area, the air agencies must consult with each 
other to employ a common technique for the area.
    (c) Monitoring. For each area identified in the notification 
submitted pursuant to paragraph (b) of this section as an area for which 
SO2 concentrations will be characterized through ambient 
monitoring, the required monitors shall be sited and operated either as 
SLAMS or in a manner equivalent to SLAMS. In either case, monitors shall 
meet applicable criteria in 40 CFR part 58, appendices A, C, and E and 
their data shall be subject to data certification and reporting 
requirements as prescribed in 40 CFR 58.15 and 58.16. These requirements 
include quarterly reporting of monitoring data to the Air Quality 
System, and the annual certification of data by May 1 of the following 
year.
    (1) The air agency shall include relevant information about monitors 
used to meet the requirements of this paragraph (c) in the air agency's 
Annual Monitoring Network Plan required by 40 CFR 58.10 due July 1, 
2016. The air agency shall consult with the appropriate EPA Regional 
Office in the development of plans to install, supplement, or maintain 
an appropriate ambient SO2 monitoring network pursuant to the 
requirements of 40 CFR part 58 and of this subpart.
    (2) All existing, new, or relocated ambient monitors intended to 
meet the requirements of this paragraph (c) must be operational by 
January 1, 2017 and must be operated continually until approved for shut 
down by EPA.
    (3) Any SO2 monitor identified by an air agency in its 
approved Annual Monitoring Network Plan as having the purpose of meeting 
the requirements of this paragraph (c) that: Is not located in an area 
designated as nonattainment as the 2010 SO2 NAAQS is not also 
being used to satisfy other ambient SO2 minimum monitoring 
requirements listed in 40 CFR part 58, appendix D, section 4.4; and is 
not otherwise required as part of a SIP, permit, attainment plan or 
maintenance plan, may be eligible for shut down upon EPA approval if it 
produces a design value no greater than 50 percent of the 2010 
SO2 NAAQS from data collected in either its first or second 
3-year period of operation. The air agency must receive EPA Regional 
Administrator approval of a request to cease operation of the monitor as 
part of the EPA's action on the Annual Monitoring Network Plan under 40 
CFR 58.10 prior to shutting down any qualifying monitor under this 
paragraph (c).
    (d) Modeling. For each area identified in the notification submitted 
pursuant to paragraph (b) of this section as an area for which 
SO2 concentrations will be characterized through air quality 
modeling, the air agency shall submit by July 1, 2016, a technical 
protocol for conducting such modeling to the Regional Administrator for 
review. The air agency shall consult with the appropriate EPA Regional 
Office in developing these modeling protocols.

[[Page 432]]

    (1) The modeling protocol shall include information about the 
modeling approach to be followed, including but not limited to the model 
to be used, modeling domain, receptor grid, emissions dataset, 
meteorological dataset and how the air agency will account for 
background SO2 concentrations.
    (2) Modeling analyses shall characterize air quality based on either 
actual SO2 emissions from the most recent 3 years, or on any 
federally enforceable allowable emission limit or limits established by 
the air agency or the EPA and that are effective and require compliance 
by January 13, 2017.
    (3) Except as provided by Sec. 51.1204, the air agency shall 
conduct the modeling analysis for any applicable source identified by 
the air agency pursuant to paragraph (a) of this section, and for its 
associated area and any nearby area, as applicable, and submit the 
modeling analysis to the EPA Regional Office by January 13, 2017.
    (e) Federally enforceable requirement to limit SO2 
emissions to under 2,000 tons per year. For each area identified in the 
notification submitted pursuant to paragraph (b) of this sectionas an 
area for which the air agency will adopt federally enforceable 
requirements in lieu of characterizing air quality through monitoring or 
modeling, the air agency shall submit documentation to the EPA by 
January 13, 2017, showing that such requirements have been adopted, are 
in effect, and been made federally enforceable by January 13, 2017, 
through an appropriate legal mechanism, and the provisions either:
    (1) Require the applicable sources in the area to emit less than 
2,000 tons of SO2 per year for calendar year 2017 and 
thereafter; or
    (2) Document that the applicable sources in the area have 
permanently shut down by January 13, 2017.



Sec. 51.1204  Enforceable emission limits providing for attainment.

    At any time prior to January 13, 2017, the air agency may submit to 
the EPA federally enforceable SO2 emissions limits (effective 
no later than January 13, 2017) for one or more applicable sources that 
provide for attainment of the 2010 SO2 NAAQS in the area 
affected by such emissions. The submittal shall include associated air 
quality modeling and other analyses that demonstrate that all modeling 
receptors in the area will not violate the 2010 SO2 NAAQS, 
taking into account the updated allowable emission limits on applicable 
sources as well as emissions limits that may apply to any other sources 
in the area. The air agency shall not be subject to the ongoing data 
requirements of Sec. 51.1205 for such area if the air quality modeling 
and other analyses demonstrate that the area will not violate the 2010 
SO2 NAAQS.



Sec. 51.1205  Ongoing data requirements.

    (a) Monitored areas. For any area where SO2 monitoring 
was conducted to characterize air quality pursuant to Sec. 51.1203, the 
air agency shall continue to operate the monitor(s) used to meet those 
requirements and shall continue to report ambient data pursuant to 
existing ambient monitoring regulations, unless the monitor(s) have been 
approved for shut down by the EPA Regional Administrator pursuant to 
Sec. 51.1203(c)(3) or pursuant to 40 CFR 58.14.
    (b) Modeled areas. For any area where modeling of actual 
SO2 emissions serve as the basis for designating such area as 
attainment for the 2010 SO2 NAAQS, the air agency shall 
submit an annual report to the EPA Regional Administrator by July 1 of 
each year, either as a stand-alone document made available for public 
inspection, or as an appendix to its Annual Monitoring Network Plan 
(also due on July 1 each year under 40 CFR 58.10), that documents the 
annual SO2 emissions of each applicable source in each such 
area and provides an assessment of the cause of any emissions increase 
from the previous year. The first report for each such area is due by 
July 1 of the calendar year after the effective date of the area's 
initial designation.
    (1) The air agency shall include in such report a recommendation 
regarding whether additional modeling is needed to characterize air 
quality in any area to determine whether the area meets or does not meet 
the 2010 SO2 NAAQS. The EPA Regional Administrator will 
consider the emissions report and air agency recommendation,

[[Page 433]]

and may require that the air agency conduct updated air quality modeling 
for the area and submit it to the EPA within 12 months.
    (2) An air agency will no longer be subject to the requirements of 
this paragraph (b) for a particular area if it provides air quality 
modeling demonstrating that air quality values at all receptors in the 
analysis are no greater than 50 percent of the 1-hour SO2 
NAAQS, and such demonstration is approved by the EPA Regional 
Administrator.
    (c) Any air agency that demonstrates that an area would meet the 
2010 SO2 NAAQS with allowable emissions is not required 
pursuant to paragraph (b) of this section to submit future annual 
reports for the area.
    (d) If modeling or monitoring information required to be submitted 
by the air agency to the EPA pursuant to this subpart indicates that an 
area is not attaining the 2010 SO2 NAAQS, the EPA may take 
appropriate action, including but not limited to requiring adoption of 
enforceable emission limits to ensure continued attainment of the 2010 
SO2 NAAQS, designation or redesignation of the area to 
nonattainment, or issuance of a SIP Call.



  Subpart CC_Provisions for Implementation of the 2015 Ozone National 
                      Ambient Air Quality Standards

    Source: 83 FR 10382, Mar. 9, 2018, unless otherwise noted.



Sec. 51.1300  Definitions.

    The following definitions apply for purposes of this subpart. Any 
term not defined herein shall have the meaning as defined in Sec. 
51.100.
    (a) 2015 NAAQS. The 2015 8-hour primary and secondary ozone NAAQS 
codified at 40 CFR 50.19.
    (b) 8-hour ozone design value. The 8-hour ozone concentration 
calculated according to 40 CFR part 50, appendix P, for the 2008 NAAQS, 
and 40 CFR part 50, appendix U, for the 2015 NAAQS.
    (c) CAA. The Clean Air Act as codified at 42 U.S.C. 7401-7671q 
(2010).
    (d) Designation for a NAAQS. The effective date of the designation 
for an area for that NAAQS.
    (e) Higher classification/lower classification. For purposes of 
determining whether a classification is higher or lower, classifications 
under subpart 2 of part D of title I of the CAA are ranked from lowest 
to highest as follows: Marginal; Moderate; Serious; Severe-15; Severe-
17; and Extreme.
    (f) 2008 ozone NAAQS means the 2008 8-hour primary and secondary 
ozone NAAQS codified at 40 CFR 50.15.
    (g) Attainment year ozone season shall mean the ozone season 
immediately preceding a nonattainment area's maximum attainment date.
    (h) Initially designated means the first designation that becomes 
effective for an area for a specific NAAQS and does not include a 
redesignation to attainment or nonattainment for that specific NAAQS.
    (i) Nitrogen Oxides (NOX) means the sum of nitric oxide 
and nitrogen dioxide in the flue gas or emission point, collectively 
expressed as nitrogen dioxide.
    (j) Ozone season means for each state (or portion of a state), the 
ozone monitoring season as defined in 40 CFR part 58, appendix D, 
section 4.1(i) for that state (or portion of a state).
    (k) Ozone transport region (OTR) means the area established by CAA 
section 184(a) or any other area established by the Administrator 
pursuant to CAA section 176A for purposes of ozone.
    (l) Reasonable further progress (RFP) means the emissions reductions 
required under CAA sections 172(c)(2), 182(c)(2)(B), 182(c)(2)(C), and 
Sec. 51.1310. The EPA interprets RFP under CAA section 172(c)(2) to be 
an average 3 percent per year emissions reduction of either VOC or 
NOX.
    (m) Rate-of-progress (ROP) means the 15 percent progress reductions 
in VOC emissions over the first 6 years after the baseline year required 
under CAA section 182(b)(1).
    (n) I/M refers to the inspection and maintenance programs for in-use 
vehicles required under the 1990 CAA Amendments and defined by subpart S 
of 40 CFR part 51.

[[Page 434]]

    (o) Current ozone NAAQS means the most recently promulgated ozone 
NAAQS at the time of application of any provision of this subpart.
    (p) Base year inventory for the nonattainment area means a 
comprehensive, accurate, current inventory of actual emissions from 
sources of VOC and NOX emitted within the boundaries of the 
nonattainment area as required by CAA section 182(a)(1).
    (q) Ozone season day emissions means an average day's emissions for 
a typical ozone season work weekday. The state shall select, subject to 
EPA approval, the particular month(s) in the ozone season and the day(s) 
in the work week to be represented, considering the conditions assumed 
in the development of RFP plans and/or emissions budgets for 
transportation conformity.

[83 FR 10382, Mar. 9, 2018, as amended at 83 FR 63032, Dec. 6, 2018]



Sec. 51.1301  Applicability of this part.

    The provisions in subparts A through Y and AA of this part apply to 
areas for purposes of the 2015 ozone NAAQS to the extent they are not 
inconsistent with the provisions of this subpart.



Sec. 51.1302  Classification and nonattainment area planning
provisions.

    An area designated nonattainment for the 2015 ozone NAAQS will be 
classified in accordance with CAA section 181, as interpreted in Sec. 
51.1303(a), and will be subject to the requirements of subpart 2 of part 
D of title I of the CAA that apply for that classification.



Sec. 51.1303  Application of classification and attainment date
provisions in CAA section 181 to areas subject to Sec. 51.1302.

    (a) In accordance with CAA section 181(a)(1), each area designated 
nonattainment for the 2015 ozone NAAQS shall be classified by operation 
of law at the time of designation. The classification shall be based on 
the 8-hour design value for the area at the time of designation, in 
accordance with Table 1 of this paragraph (a). A state may request a 
higher or lower classification as provided in paragraphs (b) and (c) of 
this section. For each area classified under this section, the 
attainment date for the 2015 NAAQS shall be as expeditious as 
practicable, but not later than the date provided in Table 1 as follows:

Table 1 to Paragraph (a)--Classifications and Attainment Dates for 2015 8-Hour Ozone NAAQS (0.070 ppm) for Areas
                                            Subject to Sec. 51.1302
----------------------------------------------------------------------------------------------------------------
                                                                                             Primary standard
                                                                         8-hour ozone     attainment date (years
               Area class                                                design value      after the effective
                                                                            (ppm)        date of designation for
                                                                                           2015 primary NAAQS)
----------------------------------------------------------------------------------------------------------------
Marginal................................  from up to *..............              0.071                        3
                                                                                  0.081
Moderate................................  from up to *..............              0.081                        6
                                                                                  0.093
Serious.................................  from up to *..............              0.093                        9
                                                                                  0.105
Severe-15...............................  from up to *..............              0.105                       15
                                                                                  0.111
Severe-17...............................  from up to *..............              0.111                       17
                                                                                  0.163
Extreme.................................  equal to or above.........              0.163                       20
----------------------------------------------------------------------------------------------------------------
* But not including.

    (b) A state may request, and the Administrator must approve, a 
higher classification for an area for any reason in accordance with CAA 
section 181(b)(3).
    (c) A state may request, and the Administrator may in the 
Administrator's discretion approve, a higher or lower classification for 
an area in accordance with CAA section 181(a)(4).



Sec. Sec. 51.1304-51.1305  [Reserved]



Sec. 51.1306  Redesignation to nonattainment following initial 
designations.

    For any area that is initially designated attainment for the 2015 
ozone

[[Page 435]]

NAAQS and that is subsequently redesignated to nonattainment for the 
2015 ozone NAAQS, any absolute, fixed date applicable in connection with 
the requirements of this part other than an attainment date is extended 
by a period of time equal to the length of time between the effective 
date of the initial designation for the 2015 ozone NAAQS and the 
effective date of the redesignation, except as otherwise provided in 
this subpart. The maximum attainment date for a redesignated area would 
be based on the area's classification, consistent with Table 1 in Sec. 
51.1303.

[83 FR 63033, Dec. 6, 2018]



Sec. 51.1307  Determining eligibility for 1-year attainment date 
extensions for an 8-hour ozone NAAQS under CAA section 181(a)(5).

    (a) A nonattainment area will meet the requirement of CAA section 
181(a)(5)(B) pertaining to 1-year extensions of the attainment date if:
    (1) For the first 1-year extension, the area's 4th highest daily 
maximum 8-hour average in the attainment year is no greater than the 
level of that NAAQS.
    (2) For the second 1-year extension, the area's 4th highest daily 
maximum 8-hour value, averaged over both the original attainment year 
and the first extension year, is no greater than the level of that 
NAAQS.
    (b) For purposes of paragraph (a)(1) of this section, the area's 4th 
highest daily maximum 8-hour average for a year shall be from the 
monitor with the highest 4th highest daily maximum 8-hour average for 
that year of all the monitors that represent that area.
    (c) For purposes of paragraph (a)(2) of this section, the area's 4th 
highest daily maximum 8-hour value, averaged over both the original 
attainment year and the first extension year, shall be from the monitor 
in each year with the highest 4th highest daily maximum 8-hour average 
of all monitors that represent that area.

[83 FR 63033, Dec. 6, 2018]



Sec. 51.1308  Modeling and attainment demonstration requirements.

    (a) An area classified Moderate under Sec. 51.1303(a) shall submit 
an attainment demonstration that provides for such specific reductions 
in emissions of VOCs and NOX as necessary to attain the 
primary NAAQS by the applicable attainment date, and such demonstration 
is due no later than 36 months after the effective date of the area's 
designation for the 2015 ozone NAAQS.
    (b) An area classified Serious or higher under Sec. 51.1303(a) 
shall be subject to the attainment demonstration requirement applicable 
for that classification under CAA section 182(c), and such demonstration 
is due no later than 48 months after the effective date of the area's 
designation for the 2015 ozone NAAQS.
    (c) An attainment demonstration due pursuant to paragraph (a) or (b) 
of this section must meet the requirements of Appendix W of this part 
and shall include inventory data, modeling results, and emission 
reduction analyses on which the state has based its projected attainment 
date; the adequacy of an attainment demonstration shall be demonstrated 
by means of a photochemical grid model or any other analytical method 
determined by the Administrator, in the Administrator's discretion, to 
be at least as effective.
    (d) Implementation of control measures. For each nonattainment area 
for which an attainment demonstration is required pursuant to paragraph 
(a) or (b) of this section, the state must provide for implementation of 
all control measures needed for attainment as expeditiously as 
practicable. All control measures in the attainment plan and 
demonstration must be implemented no later than the beginning of the 
attainment year ozone season, notwithstanding any alternate RACT and/or 
RACM implementation deadline requirements in Sec. 51.1312.

[83 FR 63033, Dec. 6, 2018]



Sec. 51.1309  [Reserved]



Sec. 51.1310  Requirements for reasonable further progress (RFP).

    (a) RFP for nonattainment areas classified pursuant to Sec. 
51.1303. The RFP requirements specified in CAA section 182 for that 
area's classification shall apply.
    (1) Submission deadline. For each area classified Moderate or higher 
pursuant

[[Page 436]]

to Sec. 51.1303, the state shall submit a SIP revision no later than 36 
months after the effective date of designation as nonattainment for the 
2015 ozone NAAQS that provides for RFP as described in paragraphs (a)(2) 
through (4) of this section.
    (2) RFP requirements for areas with an approved prior ozone NAAQS 15 
percent VOC ROP plan. An area classified Moderate or higher that has the 
same boundaries as an area, or is entirely composed of several areas or 
portions of areas, for which the EPA fully approved a 15 percent plan 
for a prior ozone NAAQS is considered to have met the requirements of 
CAA section 182(b)(1) for the 2015 ozone NAAQS and instead:
    (i) If classified Moderate, the area is subject to the RFP 
requirements under CAA section 172(c)(2) and shall submit a SIP revision 
that:
    (A) Provides for a 15 percent emission reduction from the baseline 
year within 6 years after the baseline year; and
    (B) Relies on either NOX or VOC emissions reductions (or 
a combination) to meet the requirements of paragraph (a)(2)(i)(A) of 
this section. Use of NOX emissions reductions must meet the 
criteria in CAA section 182(c)(2)(C).
    (ii) If classified Serious or higher, the area is subject to RFP 
under CAA sections 172(c)(2) and 182(c)(2)(B), and shall submit a SIP 
revision no later than 48 months after the effective date of designation 
providing for an average emissions reduction of 3 percent per year:
    (A) For the first 6-year period after the baseline year and all 
remaining 3-year periods until the year of the area's attainment date; 
and
    (B) That relies on either NOX or VOC emissions reductions 
(or a combination) to meet the requirements of (a)(2)(ii)(A). Use of 
NOX emissions reductions must meet the criteria in CAA 
section 182(c)(2)(C).
    (3) RFP requirements for areas for which an approved 15 percent VOC 
ROP plan for a prior ozone NAAQS exists for only a portion of the area. 
An area that contains one or more portions for which the EPA fully 
approved a 15 percent VOC ROP plan for a prior ozone NAAQS (as well as 
portions for which the EPA has not fully approved a 15 percent plan for 
a prior ozone NAAQS) shall meet the requirements of either paragraph 
(a)(3)(i) or (ii) of this section.
    (i) The state shall not distinguish between the portion of the area 
with a previously approved 15 percent ROP plan and the portion of the 
area without such a plan, and shall meet the requirements of paragraph 
(a)(4) of this section for the entire nonattainment area.
    (ii) The state shall treat the area as two parts, each with a 
separate RFP target as follows:
    (A) For the portion of the area without an approved 15 percent VOC 
ROP plan for a prior ozone NAAQS, the state shall submit a SIP revision 
as required under paragraph (a)(4) of this section.
    (B) For the portion of the area with an approved 15 percent VOC ROP 
plan for a prior ozone NAAQS, the state shall submit a SIP as required 
under paragraph (a)(2) of this section.
    (4) ROP Requirements for areas without an approved prior ozone NAAQS 
15 percent VOC ROP plan. (i) For each area, the state shall submit a SIP 
revision consistent with CAA section 182(b)(1). The 6-year period 
referenced in CAA section 182(b)(1) shall begin January 1 of the year 
following the year used for the baseline emissions inventory.
    (ii) For each area classified Serious or higher, the state shall 
submit a SIP revision consistent with CAA section 182(c)(2)(B). The 
final increment of progress must be achieved no later than the 
attainment date for the area.
    (5) Creditability of emission control measures for RFP plans. Except 
as specifically provided in CAA section 182(b)(1)(C) and (D), CAA 
section 182(c)(2)(B), and 40 CFR 51.1310(a)(6), all emission reductions 
from SIP-approved or federally promulgated measures that occur after the 
baseline emissions inventory year are creditable for purposes of the RFP 
requirements in this section, provided the reductions meet the 
requirements for creditability, including the need to be enforceable, 
permanent, quantifiable, and surplus.
    (6) Creditability of out-of-area emissions reductions. For purposes 
of meeting the RFP requirements in Sec. 51.1310, in addition to the 
restrictions on the creditability of emission control measures

[[Page 437]]

listed in Sec. 51.1310(a)(5), creditable emission reductions for fixed 
percentage reduction RFP must be obtained from emissions sources located 
within the nonattainment area.
    (7) Calculation of non-creditable emissions reductions. The 
following four categories of control measures listed in CAA section 
182(b)(1)(D) are no longer required to be calculated for exclusion in 
RFP analyses because the Administrator has determined that due to the 
passage of time the effect of these exclusions would be de minimis:
    (i) Measures related to motor vehicle exhaust or evaporative 
emissions promulgated by January 1, 1990;
    (ii) Regulations concerning Reid vapor pressure promulgated by 
November 15, 1990;
    (iii) Measures to correct previous RACT requirements; and
    (iv) Measures required to correct previous I/M programs.
    (b) Baseline emissions inventory for RFP plans. For the RFP plans 
required under this section, at the time of designation as nonattainment 
for an ozone NAAQS the baseline emissions inventory shall be the 
emissions inventory for the most recent calendar year for which a 
complete triennial inventory is required to be submitted to the EPA 
under the provisions of subpart A of this part. States may use an 
alternative baseline emissions inventory provided that the year selected 
corresponds with the year of the effective date of designation as 
nonattainment for that NAAQS. All states associated with a multi-state 
nonattainment area must consult and agree on using the alternative 
baseline year. The emissions values included in the inventory required 
by this section shall be actual ozone season day emissions as defined by 
Sec. 51.1300(q).
    (c) Milestones--(1) Applicable milestones. Consistent with CAA 
section 182(g)(1) for each area classified Serious or higher, the state 
shall determine at specified intervals whether each area has achieved 
the reduction in emissions required under paragraphs (a)(2) through (4) 
of this section. The initial determination shall occur 6 years after the 
baseline year, and at intervals of every 3 years thereafter. The 
reduction in emissions required by the end of each interval shall be the 
applicable milestone.
    (2) Milestone compliance demonstrations. For each area subject to 
the milestone requirements under paragraph (c)(1) of this section, not 
later than 90 days after the date on which an applicable milestone 
occurs (not including an attainment date on which a milestone occurs in 
cases where the ozone standards have been attained), each state in which 
all or part of such area is located shall submit to the Administrator a 
demonstration that the milestone has been met. The demonstration under 
this paragraph must provide for objective evaluation of RFP toward 
timely attainment of the ozone NAAQS in the area, and may take the form 
of:
    (i) Such information and analysis as needed to quantify the actual 
reduction in emissions achieved in the time interval preceding the 
applicable milestone; or
    (ii) Such information and analysis as needed to demonstrate progress 
achieved in implementing the approved SIP control measures, including 
RACM and RACT, corresponding with the reduction in emissions achieved in 
the time interval preceding the applicable milestone.

[83 FR 63033, Dec. 6, 2018]



Sec. 51.1311  [Reserved]



Sec. 51.1312  Requirements for reasonably available control technology
(RACT) and reasonably available control measures (RACM).

    (a) RACT requirement for areas classified pursuant to Sec. 51.1303. 
(1) For each nonattainment area classified Moderate or higher, the state 
shall submit a SIP revision that meets the VOC and NOX RACT 
requirements in CAA sections 182(b)(2) and 182(f).
    (2) SIP submission deadline. (i) For a RACT SIP required pursuant to 
initial nonattainment area designations, the state shall submit the RACT 
SIP for each area no later than 24 months after the effective date of 
designation for a specific ozone NAAQS.
    (ii) For a RACT SIP required pursuant to reclassification, the SIP 
revision deadline is either 24 months from the effective date of 
reclassification, or the

[[Page 438]]

deadline established by the Administrator in the reclassification 
action.
    (iii) For a RACT SIP required pursuant to the issuance of a new 
Control Techniques Guideline (CTG) under CAA section 183, the SIP 
revision deadline is either 24 months from the date of CTG issuance, or 
the deadline established by the Administrator in the action issuing the 
CTG.
    (3) RACT implementation deadline. (i) For RACT required pursuant to 
initial nonattainment area designations, the state shall provide for 
implementation of such RACT as expeditiously as practicable, but no 
later than January 1 of the fifth year after the effective date of 
designation.
    (ii) For RACT required pursuant to reclassification, the state shall 
provide for implementation of such RACT as expeditiously as practicable, 
but no later than the start of the attainment year ozone season 
associated with the area's new attainment deadline, or January 1 of the 
third year after the associated SIP revision submittal deadline, 
whichever is earlier; or the deadline established by the Administrator 
in the final action issuing the area reclassification.
    (iii) For RACT required pursuant to issuance of a new CTG under CAA 
section 183, the state shall provide for implementation of such RACT as 
expeditiously as practicable, but either no later than January 1 of the 
third year after the associated SIP submission deadline or the deadline 
established by the Administrator in the final action issuing the CTG.
    (b) Determination of major stationary sources for applicability of 
RACT provisions. The amount of VOC and NOX emissions are to 
be considered separately for purposes of determining whether a source is 
a major stationary source as defined in CAA section 302.
    (c) RACM requirements. For each nonattainment area required to 
submit an attainment demonstration under Sec. 51.1308(a) and (b), the 
state shall submit with the attainment demonstration a SIP revision 
demonstrating that it has adopted all RACM necessary to demonstrate 
attainment as expeditiously as practicable and to meet any RFP 
requirements. The SIP revision shall include, as applicable, other 
control measures on sources of emissions of ozone precursors located 
outside the nonattainment area, or portion thereof, located within the 
state if doing so is necessary or appropriate to provide for attainment 
of the applicable ozone NAAQS in such area by the applicable attainment 
date.

[83 FR 63033, Dec. 6, 2018]



Sec. 51.1313  Section 182(f) NOX exemption provisions.

    (a) A person or a state may petition the Administrator for an 
exemption from NOX obligations under CAA section 182(f) for 
any area designated nonattainment for a specific ozone NAAQS and for any 
area in a CAA section 184 ozone transport region.
    (b) The petition must contain adequate documentation that the 
criteria in CAA section 182(f) are met.
    (c) A CAA section 182(f) NOX exemption granted for a 
prior ozone NAAQS does not relieve the area from any NOX 
obligations under CAA section 182(f) for a current ozone NAAQS.

[83 FR 63033, Dec. 6, 2018]



Sec. 51.1314  New source review requirements.

    The requirements for nonattainment NSR for the ozone NAAQS are 
located in Sec. 51.165. For each nonattainment area, the state shall 
submit a nonattainment NSR plan or plan revision for a specific ozone 
NAAQS no later than 36 months after the effective date of the area's 
designation of nonattainment or redesignation to nonattainment for that 
ozone NAAQS.

[83 FR 63033, Dec. 6, 2018]



Sec. 51.1315  Emissions inventory requirements.

    (a) For each nonattainment area, the state shall submit a base year 
inventory as defined by Sec. 51.1300(p) to meet the emissions inventory 
requirement of CAA section 182(a)(1). This inventory shall be submitted 
no later than 24 months after the effective date of designation. The 
inventory year shall be selected consistent with the baseline year for 
the RFP plan as required by Sec. 51.1310(b).
    (b) For each nonattainment area, the state shall submit a periodic 
emissions

[[Page 439]]

inventory of emissions sources in the area to meet the requirement in 
CAA section 182(a)(3)(A). With the exception of the inventory year and 
timing of submittal, this inventory shall be consistent with the 
requirements of paragraph (a) of this section. Each periodic inventory 
shall be submitted no later than the end of each 3-year period after the 
required submission of the base year inventory for the nonattainment 
area. This requirement shall apply until the area is redesignated to 
attainment.
    (c) The emissions values included in the inventories required by 
paragraphs (a) and (b) of this section shall be actual ozone season day 
emissions as defined by Sec. 51.1300(q).
    (d) In the inventories required by paragraphs (a) and (b) of this 
section, the state shall report emissions from point sources according 
to the point source emissions thresholds of the Air Emissions Reporting 
Requirements, 40 CFR part 51, subpart A.
    (e) The data elements in the emissions inventories required by 
paragraphs (a) and (b) of this section shall be consistent with the 
detail required by 40 CFR part 51, subpart A. Since only emissions 
within the boundaries of the nonattainment area shall be included as 
defined by Sec. 51.1300(q), this requirement shall apply to the 
emissions inventories required in this section instead of any total 
county requirements contained in 40 CFR part 51, subpart A.

[83 FR 63033, Dec. 6, 2018]



Sec. 51.1316  Requirements for an Ozone Transport Region.

    (a) In general. CAA sections 176A and 184 apply for purposes of the 
2015 ozone NAAQS.
    (b) RACT requirements for certain portions of an ozone transport 
region. (1) The state shall submit a SIP revision that meets the RACT 
requirements of CAA section 184(b) for all portions of the state located 
in an ozone transport region.
    (2) SIP submission deadline. (i) For a RACT SIP required pursuant to 
initial nonattainment area designations, the state shall submit the RACT 
SIP revision no later than 24 months after the effective date of 
designation for a specific ozone NAAQS.
    (ii) For a RACT SIP required pursuant to reclassification, the SIP 
revision deadline is either 24 months from the effective date of 
reclassification, or the deadline established by the Administrator in 
the reclassification action.
    (iii) For a RACT SIP required pursuant to the issuance of a new CTG 
under CAA section 183, the SIP revision deadline is either 24 months 
from the date of CTG issuance, or the deadline established by the 
Administrator in the action issuing the CTG.
    (3) RACT implementation deadline. (i) For RACT required pursuant to 
initial nonattainment area designations, the state shall provide for 
implementation of RACT as expeditiously as practicable, but no later 
than January 1 of the fifth year after the effective date of 
designation.
    (ii) For RACT required pursuant to reclassification, the state shall 
provide for implementation of such RACT as expeditiously as practicable, 
but no later than the start of the attainment year ozone season 
associated with the area's new attainment deadline, or January 1 of the 
third year after the associated SIP revision submittal deadline, 
whichever is earlier; or the deadline established by the Administrator 
in the final action issuing the area reclassification.
    (iii) For RACT required pursuant to issuance of a new CTG under CAA 
section 183, the state shall provide for implementation of such RACT as 
expeditiously as practicable, but either no later than January 1 of the 
third year after the associated SIP submission deadline or the deadline 
established by the Administrator in the final action issuing the CTG.

[83 FR 63033, Dec. 6, 2018]



Sec. 51.1317  Fee programs for Severe and Extreme nonattainment areas
that fail to attain.

    For each area classified Severe or Extreme for a specific ozone 
NAAQS, the state shall submit a SIP revision within 10 years of the 
effective date of designation for that ozone NAAQS that meets the 
requirements of CAA section 185.

[83 FR 63033, Dec. 6, 2018]

[[Page 440]]



Sec. 51.1318  Suspension of SIP planning requirements in nonattainment
areas that have air quality data that meet an ozone NAAQS.

    Upon a determination by the EPA that an area designated 
nonattainment for a specific ozone NAAQS has attained that NAAQS, the 
requirements for such area to submit attainment demonstrations and 
associated RACM, RFP plans, contingency measures for failure to attain 
or make reasonable progress, and other planning SIPs related to 
attainment of the ozone NAAQS for which the determination has been made, 
shall be suspended until such time as: The area is redesignated to 
attainment for that NAAQS, at which time the requirements no longer 
apply; or the EPA determines that the area has violated that NAAQS, at 
which time the area is again required to submit such plans.

[83 FR 63033, Dec. 6, 2018]



Sec. 51.1319  [Reserved]



                Sec. Appendixes A-K to Part 51 [Reserved]



 Sec. Appendix L to Part 51--Example Regulations for Prevention of Air 
                      Pollution Emergency Episodes

    The example regulations presented herein reflect generally 
recognized ways of preventing air pollution from reaching levels that 
would cause imminent and substantial endangerment to the health of 
persons. States are required under subpart H to have emergency episodes 
plans but they are not required to adopt the regulations presented 
herein.
    1.0 Air pollution emergency. This regulation is designed to prevent 
the excessive buildup of air pollutants during air pollution episodes, 
thereby preventing the occurrence of an emergency due to the effects of 
these pollutants on the health of persons.
    1.1 Episode criteria. Conditions justifying the proclamation of an 
air pollution alert, air pollution warning, or air pollution emergency 
shall be deemed to exist whenever the Director determines that the 
accumulation of air pollutants in any place is attaining or has attained 
levels which could, if such levels are sustained or exceeded, lead to a 
substantial threat to the health of persons. In making this 
determination, the Director will be guided by the following criteria:
    (a) Air Pollution Forecast: An internal watch by the Department of 
Air Pollution Control shall be actuated by a National Weather Service 
advisory that Atmospheric Stagnation Advisory is in effect or the 
equivalent local forecast of stagnant atmospheric condition.
    (b) Alert: The Alert level is that concentration of pollutants at 
which first stage control actions is to begin. An Alert will be declared 
when any one of the following levels is reached at any monitoring site:
SO2--800 [micro]g/m\3\ (0.3 p.p.m.), 24-hour average.
PM10--350 [micro]g/m\3\, 24-hour average.
CO--17 mg/m\3\ (15 p.p.m.), 8-hour average.
Ozone (O2) = 400 [micro]g/m\3\ (0.2 ppm)-hour average.
NO2-1130 [micro]g/m\3\ (0.6 p.p.m.), 1-hour average, 282 
[micro]g/m\3\ (0.15 p.p.m.), 24-hour average.
    In addition to the levels listed for the above pollutants, 
meterological conditions are such that pollutant concentrations can be 
expected to remain at the above levels for twelve (12) or more hours or 
increase, or in the case of ozone, the situation is likely to reoccur 
within the next 24-hours unless control actions are taken.
    (c) Warning: The warning level indicates that air quality is 
continuing to degrade and that additional control actions are necessary. 
A warning will be declared when any one of the following levels is 
reached at any monitoring site:

SO2--1,600 [micro]g/m\3\ (0.6 p.p.m.), 24-hour average.
PM10--420 [micro]g/m\3\, 24-hour average.
CO--34 mg/m\3\ (30 p.p.m.), 8-hour average.
Ozone (O3)--800 [micro]g/m\3\ (0.4 p.p.m.), 1-hour average.
NO2--2,260 [micro]g/m\3\ (1.2 ppm)--1-hour average; 565 
[micro]g/m\3\ (0.3 ppm), 24-hour average.

    In addition to the levels listed for the above pollutants, 
meterological conditions are such that pollutant concentrations can be 
expected to remain at the above levels for twelve (12) or more hours or 
increase, or in the case of ozone, the situation is likely to reoccur 
within the next 24-hours unless control actions are taken.
    (d) Emergency: The emergency level indicates that air quality is 
continuing to degrade toward a level of significant harm to the health 
of persons and that the most stringent control actions are necessary. An 
emergency will be declared when any one of the following levels is 
reached at any monitoring site:

SO2--2,100 [micro]g/m\3\ (0.8 p.p.m.), 24-hour average.
    PM10--500 [micro]g/m\3\, 24-hour average.
CO--46 mg/m\3\ (40 p.p.m.), 8-hour average.
Ozone (O3)--1,000 [micro]g/m\3\ (0.5 p.p.m.), 1-hour average.
NO2-3,000 [micro]g/m\3\ (1.6 ppm), 1-hour average; 750 
[micro]g/m\3\ (0.4 ppm), 24-hour average.

    In addition to the levels listed for the above pollutants, 
meterological conditions are such that pollutant concentrations can be 
expected to remain at the above levels for twelve (12) or more hours or 
increase, or in the case of ozone, the situation is likely to

[[Page 441]]

reoccur within the next 24-hours unless control actions are taken.
    (e) Termination: Once declared, any status reached by application of 
these criteria will remain in effect until the criteria for that level 
are no longer met. At such time, the next lower status will be assumed.
    1.2 Emission reduction plans. (a) Air Pollution Alert--When the 
Director declares an Air Pollution Alert, any person responsible for the 
operation of a source of air pollutants as set forth in Table I shall 
take all Air Pollution Alert actions as required for such source of air 
pollutants and shall put into effect the preplanned abatement strategy 
for an Air Pollution Alert.
    (b) Air Pollution Warning--When the Director declares an Air 
Pollution Warning, any person responsible for the operation of a source 
of air pollutants as set forth in Table II shall take all Air Pollution 
Warning actions as required for such source of air pollutants and shall 
put into effect the preplanned abatement strategy for an Air Pollution 
Warning.
    (c) Air Pollution Emergency--When the Director declares an Air 
Pollution Emergency, any person responsible for the operation of a 
source of air pollutants as described in Table III shall take all Air 
Pollution Emergency actions as required for such source of air 
pollutants and shall put into effect the preplanned abatement strategy 
for an Air Pollution Emergency.
    (d) When the Director determines that a specified criteria level has 
been reached at one or more monitoring sites solely because of emissions 
from a limited number of sources, he shall notify such source(s) that 
the preplanned abatement strategies of Tables I, II, and III or the 
standby plans are required, insofar as it applies to such source(s), and 
shall be put into effect until the criteria of the specified level are 
no longer met.
    1.3 Preplanned abatement strategies, (a) Any person responsible for 
the operation of a source of air pollutants as set forth in Tables I-III 
shall prepare standby plans for reducing the emission of air pollutants 
during periods of an Air Pollution Alert, Air Pollution Warning, and Air 
Pollution Emergency. Standby plans shall be designed to reduce or 
eliminate emissions of air pollutants in accordance with the objectives 
set forth in Tables I-III which are made a part of this section.
    (b) Any person responsible for the operation of a source of air 
pollutants not set forth under section 1.3(a) shall, when requested by 
the Director in writing, prepare standby plans for reducing the emission 
of air pollutants during periods of an Air Pollution Alert, Air 
Pollution Warning, and Air Pollution Emergency. Standby plans shall be 
designed to reduce or eliminate emissions of air pollutants in 
accordance with the objectives set forth in Tables I-III.
    (c) Standby plans as required under section 1.3(a) and (b) shall be 
in writing and identify the sources of air pollutants, the approximate 
amount of reduction of pollutants and a brief description of the manner 
in which the reduction will be achieved during an Air Pollution Alert, 
Air Pollution Warning, and Air Pollution Emergency.
    (d) During a condition of Air Pollution Alert, Air Pollution 
Warning, and Air Pollution Emergency, standby plans as required by this 
section shall be made available on the premises to any person authorized 
to enforce the provisions of applicable rules and regulations.
    (e) Standby plans as required by this section shall be submitted to 
the Director upon request within thirty (30) days of the receipt of such 
request; such standby plans shall be subject to review and approval by 
the Director. If, in the opinion of the Director, a standby plan does 
not effectively carry out the objectives as set forth in Table I-III, 
the Director may disapprove it, state his reason for disapproval and 
order the preparation of an amended standby plan within the time period 
specified in the order.

   Table I--Abatement Strategies Emission Reduction Plans alert level

                             Part A. General

    1. There shall be no open burning by any persons of tree waste, 
vegetation, refuse, or debris in any form.
    2. The use of incinerators for the disposal of any form of solid 
waste shall be limited to the hours between 12 noon and 4 p.m.
    3. Persons operating fuel-burning equipment which required boiler 
lancing or soot blowing shall perform such operations only between the 
hours of 12 noon and 4 p.m.
    4. Persons operating motor vehicles should eliminate all unnecessary 
operations.

                       Part B. Source curtailment

    Any person responsible for the operation of a source of air 
pollutants listed below shall take all required control actions for this 
Alert Level.

[[Page 442]]



------------------------------------------------------------------------
      Source of air pollution                  Control action
------------------------------------------------------------------------
1. Coal or oil-fired electric       a. Substantial reduction by
 power generating facilities.        utilization of fuels having low ash
                                     and sulfur content.
                                    b. Maximum utilization of mid-day
                                     (12 noon to 4 p.m.) atmospheric
                                     turbulence for boiler lancing and
                                     soot blowing.
                                    c. Substantial reduction by
                                     diverting electric power generation
                                     to facilities outside of Alert
                                     Area.
2. Coal and oil-fired process       a. Substantial reduction by
 steam generating facilities.        utilization of fuels having low ash
                                     and sulfur content.
                                    b. Maximum utilization of mid-day
                                     (12 noon to 4 p.m.) atmospheric
                                     turbulence for boiler lancing and
                                     soot blowing.
                                    c. Substantial reduction of steam
                                     load demands consistent with
                                     continuing plant operations.
3. Manufacturing industries of the  a. Substantial reduction of air
 following classifications:          pollutants from manufacturing
 Primary Metals Industry.            operations by curtailing,
 Petroleum Refining Operations.      postponing, or deferring production
 Chemical Industries.                and all operations.
 Mineral Processing Industries.     b. Maximum reduction by deferring
 Paper and Allied Products.          trade waste disposal operations
 Grain Industry.                     which emit solid particles, gas
                                     vapors or malodorous substances.
                                    c. Maximum reduction of heat load
                                     demands for processing.
                                    d. Maximum utilization of mid-day
                                     (12 noon to 4 p.m.) atmospheric
                                     turbulence for boiler lancing and
                                     soot blowing.
------------------------------------------------------------------------

                   Table II--Emission Reduction Plans

                              warning level

                             Part A. General

    1. There shall be no open burning by any persons of tree waste, 
vegetation, refuse, or debris in any form.
    2. The use of incinerators for the disposal of any form of solid 
waste or liquid waste shall be prohibited.
    3. Persons operating fuel-burning equipment which requires boiler 
lancing or soot blowing shall perform such operations only between the 
hours of 12 noon and 4 p.m.
    4. Persons operating motor vehicles must reduce operations by the 
use of car pools and increased use of public transportation and 
elimination of unnecessary operation.

                       Part B. Source curtailment

    Any person responsible for the operation of a source of air 
pollutants listed below shall take all required control actions for this 
Warning Level.

------------------------------------------------------------------------
      Source of air pollution                  Control action
------------------------------------------------------------------------
1. Coal or oil-fired process steam  a. Maximum reduction by utilization
 generating facilities.              of fuels having lowest ash and
                                     sulfur content.
                                    b. Maximum utilization of mid-day
                                     (12 noon to 4 p.m.) atmospheric
                                     turbulence for boiler lancing and
                                     soot blowing.
                                    c. Maximum reduction by diverting
                                     electric power generation to
                                     facilities outside of Warning Area.
2. Oil and oil-fired process steam  a. Maximum reduction by utilization
 generating facilities.              of fuels having the lowest
                                     available ash and sulfur content.
                                    b. Maximum utilization of mid-day
                                     (12 noon to 4 p.m.) atmospheric
                                     turbulence for boiler lancing and
                                     soot blowing.
                                    c. Making ready for use a plan of
                                     action to be taken if an emergency
                                     develops.
3. Manufacturing industries which   a. Maximum reduction of air
 require considerable lead time      contaminants from manufacturing
 for shut-down including the         operations by, if necessary,
 following classifications:          assuming reasonable economic
 Petroleum Refining.                 hardships by postponing production
 Chemical Industries.                and allied operation.
 Primary Metals Industries.         b. Maximum reduction by deferring
 Glass Industries.                   trade waste disposal operations
 Paper and Allied Products.          which emit solid particles, gases,
                                     vapors or malodorous substances.
                                    c. Maximum reduction of heat load
                                     demands for processing.
                                    d. Maximum utilization of mid-day
                                     (12 noon to 4 p.m.) atmospheric
                                     turbulence for boiler lancing or
                                     soot blowing.
4. Manufacturing industries         a. Elimination of air pollutants
 require relatively short lead       from manufacturing operations by
 times for shut-down including the   ceasing, curtailing, postponing or
 following classifications:          deferring production and allied
 Primary Metals Industries.          operations to the extent possible
 Chemical Industries.                without causing injury to persons
 Mineral Processing Industries.      or damage to equipment.
 Grain Industry.                    b. Elimination of air pollutants
                                     from trade waste disposal processes
                                     which emit solid particles, gases,
                                     vapors or malodorous substances.
                                    c. Maximum reduction of heat load
                                     demands for processing.
                                    d. Maximum utilization of mid-day
                                     (12 noon to 4 p.m.) atmospheric
                                     turbulence for boiler lancing or
                                     soot blowing.
------------------------------------------------------------------------


[[Page 443]]

                   Table III--Emission Reduction Plans

                             emergency level

                             Part A. General

    1. There shall be no open burning by any persons of tree waste, 
vegetation, refuse, or debris in any form.
    2. The use of incinerators for the disposal of any form of solid or 
liquid waste shall be prohibited.
    3. All places of employment described below shall immediately cease 
operations.
    a. Mining and quarrying of nonmetallic minerals.
    b. All construction work except that which must proceed to avoid 
emergent physical harm.
    c. All manufacturing establishments except those required to have in 
force an air pollution emergency plan.
    d. All wholesale trade establishments; i.e., places of business 
primarily engaged in selling merchandise to retailers, or industrial, 
commercial, institutional or professional users, or to other 
wholesalers, or acting as agents in buying merchandise for or selling 
merchandise to such persons or companies, except those engaged in the 
distribution of drugs, surgical supplies and food.
    e. All offices of local, county and State government including 
authorities, joint meetings, and other public bodies excepting such 
agencies which are determined by the chief administrative officer of 
local, county, or State government, authorities, joint meetings and 
other public bodies to be vital for public safety and welfare and the 
enforcement of the provisions of this order.
    f. All retail trade establishments except pharmacies, surgical 
supply distributors, and stores primarily engaged in the sale of food.
    g. Banks, credit agencies other than banks, securities and 
commodities brokers, dealers, exchanges and services; offices of 
insurance carriers, agents and brokers, real estate offices.
    h. Wholesale and retail laundries, laundry services and cleaning and 
dyeing establishments; photographic studios; beauty shops, barber shops, 
shoe repair shops.
    i. Advertising offices; consumer credit reporting, adjustment and 
collection agencies; duplicating, addressing, blueprinting; 
photocopying, mailing, mailing list and stenographic services; equipment 
rental services, commercial testing laboratories.
    j. Automobile repair, automobile services, garages.
    k. Establishments rendering amusement and recreational services 
including motion picture theaters.
    l. Elementary and secondary schools, colleges, universities, 
professional schools, junior colleges, vocational schools, and public 
and private libraries.
    4. All commercial and manufacturing establishments not included in 
this order will institute such actions as will result in maximum 
reduction of air pollutants from their operation by ceasing, curtailing, 
or postponing operations which emit air pollutants to the extent 
possible without causing injury to persons or damage to equipment.
    5. The use of motor vehicles is prohibited except in emergencies 
with the approval of local or State police.

                       Part B. Source curtailment

    Any person responsible for the operation of a source of air 
pollutants listed below shall take all required control actions for this 
Emergency Level.

------------------------------------------------------------------------
      Source of air pollution                  Control action
------------------------------------------------------------------------
1. Coal or oil-fired electric       a. Maximum reduction by utilization
 power generating facilities.        of fuels having lowest ash and
                                     sulfur content.
                                    b. Maximum utilization of mid-day
                                     (12 noon to 4 p.m.) atmospheric
                                     turbulence for boiler lancing or
                                     soot blowing.
                                    c. Maximum reduction by diverting
                                     electric power generation to
                                     facilities outside of Emergency
                                     Area.
2. Coal and oil-fired process       a. Maximum reduction by reducing
 steam generating facilities.        heat and steam demands to absolute
                                     necessities consistent with
                                     preventing equipment damage.
                                    b. Maximum utilization of mid-day
                                     (12 noon to 4 p.m.) atmospheric
                                     turbulence for boiler lancing and
                                     soot blowing.
                                    c. Taking the action called for in
                                     the emergency plan.
3. Manufacturing industries of the  a. Elimination of air pollutants
 following classifications:          from manufacturing operations by
 Primary Metals Industries.          ceasing, curtailing, postponing or
 Petroleum Refining.                 deferring production and allied
 Chemical Industries.                operations to the extent possible
 Mineral Processing Industries.      without causing injury to persons
 Grain Industry.                     or damage to equipment.
 Paper and Allied Products.         b. Elimination of air pollutants
                                     from trade waste disposal processes
                                     which emit solid particles, gases,
                                     vapors or malodorous substances.
                                    c. Maximum reduction of heat load
                                     demands for processing.
                                    d. Maximum utilization of mid-day
                                     (12 noon to 4 p.m.) atmospheric
                                     turbulence for boiler lancing or
                                     soot blowing.
------------------------------------------------------------------------


[[Page 444]]


(Secs. 110, 301(a), 313, 319, Clean Air Act (42 U.S.C. 7410, 7601(a), 
7613, 7619))

[36 FR 22398, Nov. 25, 1971; 36 FR 24002, Dec. 17, 1971, as amended at 
37 FR 26312, Dec. 9, 1972; 40 FR 36333, Aug. 20, 1975; 41 FR 35676, Aug. 
24, 1976; 44 FR 27570, May 10, 1979; 51 FR 40675, Nov. 7, 1986; 52 FR 
24714, July 1, 1987]



     Sec. Appendix M to Part 51--Recommended Test Methods for State 
                          Implementation Plans

Method 201--Determination of PM10 Emissions (Exhaust Gas 
Recycle Procedure).
Method 201A--Determination of PM10 and PM2.5 
Emissions From Stationary Sources (Constant Sampling Rate Procedure)
Method 202--Dry Impinger Method for Determining Condensable Particulate 
Emissions From Stationary Sources
Method 203A--Visual Determination of Opacity of Emissions from 
Stationary Sources for Time-Averaged Regulations.
Method 203B--Visual Determination of Opacity of Emissions from 
Stationary Sources for Time-Exception Regulations.
Method 203C--Visual Determination of Opacity of Emissions from 
Stationary Sources for Instantaneous Regulations.
Method 204--Criteria for and Verification of a Permanent or Temporary 
Total Enclosure.
Method 204A--Volatile Organic Compounds Content in Liquid Input Stream.
Method 204B--Volatile Organic Compounds Emissions in Captured Stream.
Method 204C--Volatile Organic Compounds Emissions in Captured Stream 
(Dilution Technique).
Method 204D--Volatile Organic Compounds Emissions in Uncaptured Stream 
from Temporary Total Enclosure.
Method 204E--Volatile Organic Compounds Emissions in Uncaptured Stream 
from Building Enclosure.
Method 204F--Volatile Organic Compounds Content in Liquid Input Stream 
(Distillation Approach).
Method 205--Verification of Gas Dilution Systems for Field Instrument 
Calibrations
Method 207--Pre-Survey Procedure for Corn Wet-Milling Facility Emission 
Sources

    1.0 Presented herein are recommended test methods for measuring air 
pollutantemanating from an emission source. They are provided for States 
to use in their plans to meet the requirements of subpart K--Source 
Surveillance.
    2.0 The State may also choose to adopt other methods to meet the 
requirements of subpart K of this part, subject to the normal plan 
review process.
    3.0 The State may also meet the requirements of subpart K of this 
part by adopting, again subject to the normal plan review process, any 
of the relevant methods in appendix A to 40 CFR part 60.
    4.0 Quality Assurance Procedures. The performance testing shall 
include a test method performance audit (PA) during the performance 
test. The PAs consist of blind audit samples supplied by an accredited 
audit sample provider and analyzed during the performance test in order 
to provide a measure of test data bias. Gaseous audit samples are 
designed to audit the performance of the sampling system as well as the 
analytical system and must be collected by the sampling system during 
the compliance test just as the compliance samples are collected. If a 
liquid or solid audit sample is designed to audit the sampling system, 
it must also be collected by the sampling system during the compliance 
test. If multiple sampling systems or sampling trains are used during 
the compliance test for any of the test methods, the tester is only 
required to use one of the sampling systems per method to collect the 
audit sample. The audit sample must be analyzed by the same analyst 
using the same analytical reagents and analytical system and at the same 
time as the compliance samples. Retests are required when there is a 
failure to produce acceptable results for an audit sample. However, if 
the audit results do not affect the compliance or noncompliance status 
of the affected facility, the compliance authority may waive the 
reanalysis requirement, further audits, or retests and accept the 
results of the compliance test. Acceptance of the test results shall 
constitute a waiver of the reanalysis requirement, further audits, or 
retests. The compliance authority may also use the audit sample failure 
and the compliance test results as evidence to determine the compliance 
or noncompliance status of the affected facility. A blind audit sample 
is a sample whose value is known only to the sample provider and is not 
revealed to the tested facility until after it reports the measured 
value of the audit sample. For pollutants that exist in the gas phase at 
ambient temperature, the audit sample shall consist of an appropriate 
concentration of the pollutant in air or nitrogen that will be 
introduced into the sampling system of the test method at or near the 
same entry point as a sample from the emission source. If no gas phase 
audit samples are available, an acceptable alternative is a sample of 
the pollutant in the same matrix that would be produced when the sample 
is recovered from the sampling system as required by the test method. 
For samples that exist only in a liquid or solid form at ambient 
temperature, the audit sample shall consist of an appropriate 
concentration of the

[[Page 445]]

pollutant in the same matrix that would be produced when the sample is 
recovered from the sampling system as required by the test method. An 
accredited audit sample provider (AASP) is an organization that has been 
accredited to prepare audit samples by an independent, third party 
accrediting body.
    a. The source owner, operator, or representative of the tested 
facility shall obtain an audit sample, if commercially available, from 
an AASP for each test method used for regulatory compliance purposes. No 
audit samples are required for the following test methods: Methods 3A 
and 3C of appendix A-3 of part 60 of this chapter, Methods 6C, 7E, 9, 
and 10 of appendix A-4 of part 60, Methods 18 and 19 of appendix A-6 of 
part 60, Methods 20, 22, and 25A of appendix A-7 of part 60, Methods 30A 
and 30B of appendix A-8 of part 60, and Methods 303, 318, 320, and 321 
of appendix A of part 63 of this chapter. If multiple sources at a 
single facility are tested during a compliance test event, only one 
audit sample is required for each method used during a compliance test. 
The compliance authority responsible for the compliance test may waive 
the requirement to include an audit sample if they believe that an audit 
sample is not necessary. ``Commercially available'' means that two or 
more independent AASPs have blind audit samples available for purchase. 
If the source owner, operator, or representative cannot find an audit 
sample for a specific method, the owner, operator, or representative 
shall consult the EPA Web site at the following URL, http://www.epa.gov/
ttn/emc, to confirm whether there is a source that can supply an audit 
sample for that method. If the EPA Web site does not list an available 
audit sample at least 60 days prior to the beginning of the compliance 
test, the source owner, operator, or representative shall not be 
required to include an audit sample as part of the quality assurance 
program for the compliance test. When ordering an audit sample, the 
source owner, operator, or representative shall give the sample provider 
an estimate for the concentration of each pollutant that is emitted by 
the source or the estimated concentration of each pollutant based on the 
permitted level and the name, address, and phone number of the 
compliance authority. The source owner, operator, or representative 
shall report the results for the audit sample along with a summary of 
the emissions test results for the audited pollutant to the compliance 
authority and shall report the results of the audit sample to the AASP. 
The source owner, operator, or representative shall make both reports at 
the same time and in the same manner or shall report to the compliance 
authority first and then report to the AASP. If the method being audited 
is a method that allows the samples to be analyzed in the field, and the 
tester plans to analyze the samples in the field, the tester may analyze 
the audit samples prior to collecting the emission samples provided a 
representative of the compliance authority is present at the testing 
site. The tester may request and the compliance authority may grant a 
waiver to the requirement that a representative of the compliance 
authority must be present at the testing site during the field analysis 
of an audit sample. The source owner, operator, or representative may 
report the results of the audit sample to the compliance authority and 
then report the results of the audit sample to the AASP prior to 
collecting any emission samples. The test protocol and final test report 
shall document whether an audit sample was ordered and utilized and the 
pass/fail results as applicable.
    b. An AASP shall have and shall prepare, analyze, and report the 
true value of audit samples in accordance with a written technical 
criteria document that describes how audit samples will be prepared and 
distributed in a manner that will ensure the integrity of the audit 
sample program. An acceptable technical criteria document shall contain 
standard operating procedures for all of the following operations:
    1. Preparing the sample;
    2. Confirming the true concentration of the sample;
    3. Defining the acceptance limits for the results from a well 
qualified tester. This procedure must use well established statistical 
methods to analyze historical results from well qualified testers. The 
acceptance limits shall be set so that there is 95 percent confidence 
that 90 percent of well qualified labs will produce future results that 
are within the acceptance limit range;
    4. Providing the opportunity for the compliance authority to comment 
on the selected concentration level for an audit sample;
    5. Distributing the sample to the user in a manner that guarantees 
that the true value of the sample is unknown to the user;
    6. Recording the measured concentration reported by the user and 
determining if the measured value is within acceptable limits;
    7. Report the results from each audit sample in a timely manner to 
the compliance authority and to the source owner, operator, or 
representative by the AASP. The AASP shall make both reports at the same 
time and in the same manner or shall report to the compliance authority 
first and then report to the source owner, operator, or representative. 
The results shall include the name of the facility tested, the date on 
which the compliance test was conducted, the name of the company 
performing the sample collection, the name of the company that analyzed 
the compliance samples including the audit sample, the measured result 
for the audit sample, and whether the testing company passed or failed 
the audit. The AASP shall report

[[Page 446]]

the true value of the audit sample to the compliance authority. The AASP 
may report the true value to the source owner, operator, or 
representative if the AASP's operating plan ensures that no laboratory 
will receive the same audit sample twice.
    8. Evaluating the acceptance limits of samples at least once every 
two years to determine in consultation with the voluntary consensus 
standard body if they should be changed;
    9. Maintaining a database, accessible to the compliance authorities, 
of results from the audit that shall include the name of the facility 
tested, the date on which the compliance test was conducted, the name of 
the company performing the sample collection, the name of the company 
that analyzed the compliance samples including the audit sample, the 
measured result for the audit sample, the true value of the audit 
sample, the acceptance range for the measured value, and whether the 
testing company passed or failed the audit.
    c. The accrediting body shall have a written technical criteria 
document that describes how it will ensure that the AASP is operating in 
accordance with the AASP technical criteria document that describes how 
audit samples are to be prepared and distributed. This document shall 
contain standard operating procedures for all of the following 
operations:
    1. Checking audit samples to confirm their true value as reported by 
the AASP;
    2. Performing technical systems audits of the AASP's facilities and 
operating procedures at least once every 2 years.
    3. Providing standards for use by the voluntary consensus standard 
body to approve the accrediting body that will accredit the audit sample 
providers.
    d. The technical criteria documents for the accredited sample 
providers and the accrediting body shall be developed through a public 
process guided by a voluntary consensus standards body (VCSB). The VCSB 
shall operate in accordance with the procedures and requirements in the 
Office of Management and Budget Circular A-119. A copy of Circular A-119 
is available upon request by writing the Office of Information and 
Regulatory Affairs, Office of Management and Budget, 725 17th Street, 
NW., Washington, DC 20503, by calling (202) 395-6880 or by downloading 
online at http://standards.gov/standards_gov/a119.cfm. The VCSB shall 
approve all accrediting bodies. The Administrator will review all 
technical criteria documents. If the technical criteria documents do not 
meet the minimum technical requirements in this Appendix M, paragraphs 
b. through d., the technical criteria documents are not acceptable and 
the proposed audit sample program is not capable of producing audit 
samples of sufficient quality to be used in a compliance test. All 
acceptable technical criteria documents shall be posted on the EPA Web 
site at the following URL, http://www.epa.gov/ttn/emc.

         Method 201--Determination of PM10 Emissions

                     (exhaust gas recycle procedure)

                     1. Applicability and Principle

    1.1 Applicability. This method applies to the in-stack measurement 
of particulate matter (PM) emissions equal to or less than an 
aerodynamic diameter of nominally 10 [micro]m (PM10) from 
stationary sources. The EPA recognizes that condensible emissions not 
collected by an in-stack method are also PM10, and that 
emissions that contribute to ambient PM10 levels are the sum 
of condensible emissions and emissions measured by an in-stack 
PM10 method, such as this method or Method 201A. Therefore, 
for establishing source contributions to ambient levels of 
PM10, such as for emission inventory purposes, EPA suggests 
that source PM10 measurement include both in-stack 
PM10 and condensible emissions. Condensible missions may be 
measured by an impinger analysis in combination with this method.
    1.2 Principle. A gas sample is isokinetically extracted from the 
source. An in-stack cyclone is used to separate PM greater than 
PM10, and an in-stack glass fiber filter is used to collect 
the PM10. To maintain isokinetic flow rate conditions at the 
tip of the probe and a constant flow rate through the cyclone, a clean, 
dried portion of the sample gas at stack temperature is recycled into 
the nozzle. The particulate mass is determined gravimetrically after 
removal of uncombined water.

                              2. Apparatus

    Note: Method 5 as cited in this method refers to the method in 40 
CFR part 60, appendix A.

    2.1 Sampling Train. A schematic of the exhaust of the exhaust gas 
recycle (EGR) train is shown in Figure 1 of this method.
    2.1.1 Nozzle with Recycle Attachment. Stainless steel (316 or 
equivalent) with a sharp tapered leading edge, and recycle attachment 
welded directly on the side of the nozzle (see schematic in Figure 2 of 
this method). The angle of the taper shall be on the outside. Use only 
straight sampling nozzles. ``Gooseneck'' or other nozzle extensions 
designed to turn the sample gas flow 90[deg], as in Method 5 are not 
acceptable. Locate a thermocouple in the recycle attachment to measure 
the temperature of the recycle gas as shown in Figure 3 of this method. 
The recycle attachment shall be made of stainless steel and shall be 
connected to the probe and nozzle with stainless steel fittings. Two 
nozzle sizes, e.g., 0.125 and 0.160 in., should be available to allow 
isokinetic sampling to be

[[Page 447]]

conducted over a range of flow rates. Calibrate each nozzle as described 
in Method 5, Section 5.1.
    2.1.2 PM10 Sizer. Cyclone, meeting the specifications in 
Section 5.7 of this method.
    2.1.3 Filter Holder. 63mm, stainless steel. An Andersen filter, part 
number SE274, has been found to be acceptable for the in-stack filter.

    Note: Mention of trade names or specific products does not 
constitute endorsement by the Environmental Protection Agency.

    2.1.4 Pitot Tube. Same as in Method 5, Section 2.1.3. Attach the 
pitot to the pitot lines with stainless steel fittings and to the 
cyclone in a configuration similar to that shown in Figure 3 of this 
method. The pitot lines shall be made of heat resistant material and 
attached to the probe with stainless steel fittings.
    2.1.5 EGR Probe. Stainless steel, 15.9-mm (\5/8\-in.) ID tubing with 
a probe liner, stainless steel 9.53-mm (\3/8\-in.) ID stainless steel 
recycle tubing, two 6.35-mm (\1/4\-in.) ID stainless steel tubing for 
the pitot tube extensions, three thermocouple leads, and one power lead, 
all contained by stainless steel tubing with a diameter of approximately 
51 mm (2.0 in.). Design considerations should include minimum weight 
construction materials sufficient for probe structural strength. Wrap 
the sample and recycle tubes with a heating tape to heat the sample and 
recycle gases to stack temperature.
    2.1.6 Condenser. Same as in Method 5, Section 2.1.7.
    2.1.7 Umbilical Connector. Flexible tubing with thermocouple and 
power leads of sufficient length to connect probe to meter and flow 
control console.
    2.1.8 Vacuum Pump. Leak-tight, oil-less, noncontaminating, with an 
absolute filter, ``HEPA'' type, at the pump exit. A Gast Model 0522-V103 
G18DX pump has been found to be satisfactory.
    2.1.9 Meter and Flow Control Console. System consisting of a dry gas 
meter and calibrated orifice for measuring sample flow rate and capable 
of measuring volume to 2 percent, calibrated 
laminar flow elements (LFE's) or equivalent for measuring total and 
sample flow rates, probe heater control, and manometers and magnehelic 
gauges (as shown in Figures 4 and 5 of this method), or equivalent. 
Temperatures needed for calculations include stack, recycle, probe, dry 
gas meter, filter, and total flow. Flow measurements include velocity 
head ([Delta]p), orifice differential pressure ([Delta]H), total flow, 
recycle flow, and total back-pressure through the system.
    2.1.10 Barometer. Same as in Method 5, Section 2.1.9.
    2.1.11 Rubber Tubing. 6.35-mm (1/4-in.) ID flexible 
rubber tubing.
    2.2 Sample Recovery.
    2.2.1 Nozzle, Cyclone, and Filter Holder Brushes. Nylon bristle 
brushes property sized and shaped for cleaning the nozzle, cyclone, 
filter holder, and probe or probe liner, with stainless steel wire 
shafts and handles.
    2.2.2 Wash Bottles, Glass Sample Storage Containers, Petri Dishes, 
Graduated Cylinder and Balance, Plastic Storage Containers, and Funnels. 
Same as Method 5, Sections 2.2.2 through 2.2.6 and 2.2.8, respectively.
    2.3 Analysis. Same as in Method 5, Section 2.3.

                               3. Reagents

    The reagents used in sampling, sample recovery, and analysis are the 
same as that specified in Method 5, Sections 3.1, 3.2, and 3.3, 
respectively.

                              4. Procedure

    4.1 Sampling. The complexity of this method is such that, in order 
to obtain reliable results, testers should be trained and experienced 
with the test procedures.
    4.1.1 Pretest Preparation. Same as in Method 5, Section 4.1.1.
    4.1.2 Preliminary Determinations. Same as Method 5, Section 4.1.2, 
except use the directions on nozzle size selection in this section. Use 
of the EGR method may require a minimum sampling port diameter of 0.2 m 
(6 in.). Also, the required maximum number of sample traverse points at 
any location shall be 12.
    4.1.2.1 The cyclone and filter holder must be in-stack or at stack 
temperature during sampling. The blockage effects of the EGR sampling 
assembly will be minimal if the cross-sectional area of the sampling 
assembly is 3 percent or less of the cross-sectional area of the duct 
and a pitot coefficient of 0.84 may be assigned to the pitot. If the 
cross-sectional area of the assembly is greater than 3 percent of the 
cross-sectional area of the duct, then either determine the pitot 
coefficient at sampling conditions or use a standard pitot with a known 
coefficient in a configuration with the EGR sampling assembly such that 
flow disturbances are minimized.
    4.1.2.2 Construct a setup of pressure drops for various [Delta]p's 
and temperatures. A computer is useful for these calculations. An 
example of the output of the EGR setup program is shown in Figure 6 of 
this method, and directions on its use are in section 4.1.5.2 of this 
method. Computer programs, written in IBM BASIC computer language, to do 
these types of setup and reduction calculations for the EGR procedure, 
are available through the National Technical Information Services 
(NTIS), Accession number PB90-500000, 5285 Port Royal Road, Springfield, 
VA 22161.

[[Page 448]]

    4.1.2.3 The EGR setup program allows the tester to select the nozzle 
size based on anticipated average stack conditions and prints a setup 
sheet for field use. The amount of recycle through the nozzle should be 
between 10 and 80 percent. Inputs for the EGR setup program are stack 
temperature (minimum, maximum, and average), stack velocity (minimum, 
maximum, and average), atmospheric pressure, stack static pressure, 
meter box temperature, stack moisture, percent 02, and 
percent CO2 in the stack gas, pitot coefficient 
(Cp), orifice [Delta] H2, flow rate measurement 
calibration values [slope (m) and y-intercept (b) of the calibration 
curve], and the number of nozzles available and their diameters.
    4.1.2.4 A less rigorous calculation for the setup sheet can be done 
manually using the equations on the example worksheets in Figures 7, 8, 
and 9 of this method, or by a Hewlett-Packard HP41 calculator using the 
program provided in appendix D of the EGR operators manual, entitled 
Applications Guide for Source PM10 Exhaust Gas Recycle 
Sampling System. This calculation uses an approximation of the total 
flow rate and agrees within 1 percent of the exact solution for pressure 
drops at stack temperatures from 38 to 260 [deg]C (100 to 500 [deg]F) 
and stack moisture up to 50 percent. Also, the example worksheets use a 
constant stack temperature in the calculation, ingoring the complicated 
temperature dependence from all three pressure drop equations. Errors 
for this at stack temperatures 28 [deg]C (50 [deg]F) of the temperature used in the setup 
calculations are within 5 percent for flow rate and within 5 percent for 
cyclone cut size.
    4.1.2.5 The pressure upstream of the LFE's is assumed to be constant 
at 0.6 in. Hg in the EGR setup calculations.
    4.1.2.6 The setup sheet constructed using this procedure shall be 
similar to Figure 6 of this method. Inputs needed for the calculation 
are the same as for the setup computer except that stack velocities are 
not needed.
    4.1.3 Preparation of Collection Train. Same as in Method 5, Section 
4.1.3, except use the following directions to set up the train.
    4.1.3.1 Assemble the EGR sampling device, and attach it to probe as 
shown in Figure 3 of this method. If stack temperatures exceed 260 
[deg]C (500 [deg]F), then assemble the EGR cyclone without the O-ring 
and reduce the vacuum requirement to 130 mm Hg (5.0 in. Hg) in the leak-
check procedure in Section 4.1.4.3.2 of this method.
    4.1.3.2 Connect the proble directly to the filter holder and 
condenser as in Method 5. Connect the condenser and probe to the meter 
and flow control console with the umbilical connector. Plug in the pump 
and attach pump lines to the meter and flow control console.
    4.1.4 Leak-Check Procedure. The leak-check for the EGR Method 
consists of two parts: the sample-side and the recycle-side. The sample-
side leak-check is required at the beginning of the run with the cyclone 
attached, and after the run with the cyclone removed. The cyclone is 
removed before the post-test leak-check to prevent any disturbance of 
the collected sample prior to analysis. The recycle-side leak-check 
tests the leak tight integrity of the recycle components and is required 
prior to the first test run and after each shipment.
    4.1.4.1 Pretest Leak-Check. A pretest leak-check of the entire 
sample-side, including the cyclone and nozzle, is required. Use the 
leak-check procedure in Section 4.1.4.3 of this method to conduct a 
pretest leak-check.
    4.1.4.2 Leak-Checks During Sample Run. Same as in Method 5, Section 
4.1.4.1.
    4.1.4.3 Post-Test Leak-Check. A leak-check is required at the 
conclusion of each sampling run. Remove the cyclone before the leak-
check to prevent the vacuum created by the cooling of the probe from 
disturbing the collected sample and use the following procedure to 
conduct a post-test leak-check.
    4.1.4.3.1 The sample-side leak-check is performed as follows: After 
removing the cyclone, seal the probe with a leak-tight stopper. Before 
starting pump, close the coarse total valve and both recycle valves, and 
open completely the sample back pressure valve and the fine total valve. 
After turning the pump on, partially open the coarse total valve slowly 
to prevent a surge in the manometer. Adjust the vacuum to at least 381 
mm Hg (15.0 in. Hg) with the fine total valve. If the desired vacuum is 
exceeded, either leak-check at this higher vacuum or end the leak-check 
as shown below and start over.

    Caution: Do not decrease the vacuum with any of the valves. This may 
cause a rupture of the filter.

    Note: A lower vacuum may be used, provided that it is not exceeded 
during the test.

    4.1.4.3.2 Leak rates in excess of 0.00057 m\3\/min (0.020 ft\3\/min) 
are unacceptable. If the leak rate is too high, void the sampling run.
    4.1.4.3.3 To complete the leak-check, slowly remove the stopper from 
the nozzle until the vacuum is near zero, then immediately turn off the 
pump. This procedure sequence prevents a pressure surge in the manometer 
fluid and rupture of the filter.
    4.1.4.3.4 The recycle-side leak-check is performed as follows: Close 
the coarse and fine total valves and sample back pressure valve. Plug 
the sample inlet at the meter box. Turn on the power and the pump, close 
the recycle valves, and open the total flow valves. Adjust the total 
flow fine adjust valve until a vacuum of 25 inches of mercury is 
achieved. If the desired vacuum is exceeded, either leak-check at this 
higher vacuum, or end the

[[Page 449]]

leak-check and start over. Minimum acceptable leak rates are the same as 
for the sample-side. If the leak rate is too high, void the sampling 
run.
    4.1.5 EGR Train Operation. Same as in Method 5, Section 4.1.5, 
except omit references to nomographs and recommendations about changing 
the filter assembly during a run.
    4.1.5.1 Record the data required on a data sheet such as the one 
shown in Figure 10 of this method. Make periodic checks of the manometer 
level and zero to ensure correct [Delta]H and [Delta]p values. An 
acceptable procedure for checking the zero is to equalize the pressure 
at both ends of the manometer by pulling off the tubing, allowing the 
fluid to equilibrate and, if necessary, to re-zero. Maintain the probe 
temperature to within 11 [deg]C (20 [deg]F) of stack temperature.
    4.1.5.2 The procedure for using the example EGR setup sheet is as 
follows: Obtain a stack velocity reading from the pitot manometer 
([Delta]p), and find this value on the ordinate axis of the setup sheet. 
Find the stack temperature on the abscissa. Where these two values 
intersect are the differential pressures necessary to achieve 
isokineticity and 10 [micro]m cut size (interpolation may be necessary).
    4.1.5.3 The top three numbers are differential pressures (in. 
H2 O), and the bottom number is the percent recycle at these 
flow settings. Adjust the total flow rate valves, coarse and fine, to 
the sample value ([Delta]H) on the setup sheet, and the recycle flow 
rate valves, coarse and fine, to the recycle flow on the setup sheet.
    4.1.5.4 For startup of the EGR sample train, the following procedure 
is recommended. Preheat the cyclone in the stack for 30 minutes. Close 
both the sample and recycle coarse valves. Open the fine total, fine 
recycle, and sample back pressure valves halfway. Ensure that the nozzle 
is properly aligned with the sample stream. After noting the [Delta]p 
and stack temperature, select the appropriate [Delta]H and recycle from 
the EGR setup sheet. Start the pump and timing device simultaneously. 
Immediately open both the coarse total and the coarse recycle valves 
slowly to obtain the approximate desired values. Adjust both the fine 
total and the fine recycle valves to achieve more precisely the desired 
values. In the EGR flow system, adjustment of either valve will result 
in a change in both total and recycle flow rates, and a slight iteration 
between the total and recycle valves may be necessary. Because the 
sample back pressure valve controls the total flow rate through the 
system, it may be necessary to adjust this valve in order to obtain the 
correct flow rate.

    Note: Isokinetic sampling and proper operation of the cyclone are 
not achieved unless the correct [Delta]H and recycle flow rates are 
maintained.

    4.1.5.5 During the test run, monitor the probe and filter 
temperatures periodically, and make adjustments as necessary to maintain 
the desired temperatures. If the sample loading is high, the filter may 
begin to blind or the cyclone may clog. The filter or the cyclone may be 
replaced during the sample run. Before changing the filter or cyclone, 
conduct a leak-check (Section 4.1.4.2 of this method). The total 
particulate mass shall be the sum of all cyclone and the filter catch 
during the run. Monitor stack temperature and [Delta]p periodically, and 
make the necessary adjustments in sampling and recycle flow rates to 
maintain isokinetic sampling and the proper flow rate through the 
cyclone. At the end of the run, turn off the pump, close the coarse 
total valve, and record the final dry gas meter reading. Remove the 
probe from the stack, and conduct a post-test leak-check as outlined in 
Section 4.1.4.3 of this method.
    4.2 Sample Recovery. Allow the probe to cool. When the probe can be 
safely handled, wipe off all external PM adhering to the outside of the 
nozzle, cyclone, and nozzle attachment, and place a cap over the nozzle 
to prevent losing or gaining PM. Do not cap the nozzle tip tightly while 
the sampling train is cooling, as this action would create a vacuum in 
the filter holder. Disconnect the probe from the umbilical connector, 
and take the probe to the cleanup site. Sample recovery should be 
conducted in a dry indoor area or, if outside, in an area protected from 
wind and free of dust. Cap the ends of the impingers and carry them to 
the cleanup site. Inspect the components of the train prior to and 
during disassembly to note any abnormal conditions. Disconnect the pitot 
from the cyclone. Remove the cyclone from the probe. Recover the sample 
as follows:
    4.2.1 Container Number 1 (Filter). The recovery shall be the same as 
that for Container Number 1 in Method 5, Section 4.2.
    4.2.2 Container Number 2 (Cyclone or Large PM Catch). The cyclone 
must be disassembled and the nozzle removed in order to recover the 
large PM catch. Quantitatively recover the PM from the interior surfaces 
of the nozzle and the cyclone, excluding the ``turn around'' cup and the 
interior surfaces of the exit tube. The recovery shall be the same as 
that for Container Number 2 in Method 5, Section 4.2.
    4.2.3 Container Number 3 (PM10). Quantitatively recover 
the PM from all of the surfaces from cyclone exit to the front half of 
the in-stack filter holder, including the ``turn around'' cup and the 
interior of the exit tube. The recovery shall be the same as that for 
Container Number 2 in Method 5, Section 4.2.
    4.2.4 Container Number 4 (Silica Gel). Same as that for Container 
Number 3 in Method 5, Section 4.2.

[[Page 450]]

    4.2.5 Impinger Water. Same as in Method 5, Section 4.2, under 
``Impinger Water.''
    4.3 Analysis. Same as in Method 5, Section 4.3, except handle EGR 
Container Numbers 1 and 2 like Container Number 1 in Method 5, EGR 
Container Numbers 3, 4, and 5 like Container Number 3 in Method 5, and 
EGR Container Number 6 like Container Number 3 in Method 5. Use Figure 
11 of this method to record the weights of PM collected.
    4.4 Quality Control Procedures. Same as in Method 5, Section 4.4.
    4.5 PM10 Emission Calculation and Acceptability of 
Results. Use the EGR reduction program or the procedures in section 6 of 
this method to calculate PM10 emissions and the criteria in 
section 6.7 of this method to determine the acceptability of the 
results.

                             5. Calibration

    Maintain an accurate laboratory log of all calibrations.
    5.1 Probe Nozzle. Same as in Method 5, Section 5.1.
    5.2 Pitot Tube. Same as in Method 5, Section 5.2.
    5.3 Meter and Flow Control Console.
    5.3.1 Dry Gas Meter. Same as in Method 5, Section 5.3.
    5.3.2 LFE Gauges. Calibrate the recycle, total, and inlet total LFE 
gauges with a manometer. Read and record flow rates at 10, 50, and 90 
percent of full scale on the total and recycle pressure gauges. Read and 
record flow rates at 10, 20, and 30 percent of full scale on the inlet 
total LFE pressure gauge. Record the total and recycle readings to the 
nearest 0.3 mm (0.01 in.). Record the inlet total LFE readings to the 
nearest 3 mm (0.1 in.). Make three separate measurements at each setting 
and calculate the average. The maximum difference between the average 
pressure reading and the average manometer reading shall not exceed 1 mm 
(0.05 in.). If the differences exceed the limit specified, adjust or 
replace the pressure gauge. After each field use, check the calibration 
of the pressure gauges.
    5.3.3 Total LFE. Same as the metering system in Method 5, Section 
5.3.
    5.3.4 Recycle LFE. Same as the metering system in Method 5, Section 
5.3, except completely close both the coarse and fine recycle valves.
    5.4 Probe Heater. Connect the probe to the meter and flow control 
console with the umbilical connector. Insert a thermocouple into the 
probe sample line approximately half the length of the probe sample 
line. Calibrate the probe heater at 66 [deg]C (150 [deg]F), 121 [deg]C 
(250 [deg]F), and 177 [deg]C (350 [deg]F). Turn on the power, and set 
the probe heater to the specified temperature. Allow the heater to 
equilibrate, and record the thermocouple temperature and the meter and 
flow control console temperature to the nearest 0.5 [deg]C (1 [deg]F). 
The two temperatures should agree within 5.5 [deg]C (10 [deg]F). If this 
agreement is not met, adjust or replace the probe heater controller.
    5.5 Temperature Gauges. Connect all thermocouples, and let the meter 
and flow control console equilibrate to ambient temperature. All 
thermocouples shall agree to within 1.1 [deg]C (2.0 [deg]F) with a 
standard mercury-in-glass thermometer. Replace defective thermocouples.
    5.6 Barometer. Calibrate against a standard mercury-in-glass 
barometer.
    5.7 Probe Cyclone and Nozzle Combinations. The probe cyclone and 
nozzle combinations need not be calibrated if the cyclone meets the 
design specifications in Figure 12 of this method and the nozzle meets 
the design specifications in appendix B of the Application Guide for the 
Source PM\3\10 Exhaust Gas Recycle Sampling System, EPA/600/
3-88-058. This document may be obtained from Roy Huntley at (919) 541-
1060. If the nozzles do not meet the design specifications, then test 
the cyclone and nozzle combination for conformity with the performance 
specifications (PS's) in Table 1 of this method. The purpose of the PS 
tests is to determine if the cyclone's sharpness of cut meets minimum 
performance criteria. If the cyclone does not meet design 
specifications, then, in addition to the cyclone and nozzle combination 
conforming to the PS's, calibrate the cyclone and determine the 
relationship between flow rate, gas viscosity, and gas density. Use the 
procedures in Section 5.7.5 of this method to conduct PS tests and the 
procedures in Section 5.8 of this method to calibrate the cyclone. 
Conduct the PS tests in a wind tunnel described in Section 5.7.1 of this 
method and using a particle generation system described in Section 5.7.2 
of this method. Use five particle sizes and three wind velocities as 
listed in Table 2 of this method. Perform a minimum of three replicate 
measurements of collection efficiency for each of the 15 conditions 
listed, for a minimum of 45 measurements.
    5.7.1 Wind Tunnel. Perform calibration and PS tests in a wind tunnel 
(or equivalent test apparatus) capable of establishing and maintaining 
the required gas stream velocities within 10 percent.
    5.7.2 Particle Generation System. The particle generation system 
shall be capable of producing solid monodispersed dye particles with the 
mass median aerodynamic diameters specified in Table 2 of this method. 
The particle size distribution verification should be performed on an 
integrated sample obtained during the sampling period of each test. An 
acceptable alternative is to verify the size distribution of samples 
obtained before and after each test, with both samples required to meet 
the diameter and monodispersity requirements for an acceptable test run.
    5.7.2.1 Establish the size of the solid dye particles delivered to 
the test section of the

[[Page 451]]

wind tunnel using the operating parameters of the particle generation 
system, and verify the size during the tests by microscopic examination 
of samples of the particles collected on a membrane filter. The particle 
size, as established by the operating parameters of the generation 
system, shall be within the tolerance specified in Table 2 of this 
method. The precision of the particle size verification technique shall 
be at least 0.5 [micro]m, and the particle size 
determined by the verification technique shall not differ by more than 
10 percent from that established by the operating parameters of the 
particle generation system.
    5.7.2.2 Certify the monodispersity of the particles for each test 
either by microscopic inspection of collected particles on filters or by 
other suitable monitoring techniques such as an optical particle counter 
followed by a multichannel pulse height analyzer. If the proportion of 
multiplets and satellites in an aerosol exceeds 10 percent by mass, the 
particle generation system is unacceptable for purposes of this test. 
Multiplets are particles that are agglomerated, and satellites are 
particles that are smaller than the specified size range.
    5.7.3 Schematic Drawings. Schematic drawings of the wind tunnel and 
blower system and other information showing complete procedural details 
of the test atmosphere generation, verification, and delivery techniques 
shall be furnished with calibration data to the reviewing agency.
    5.7.4 Flow Rate Measurement. Determine the cyclone flow rates with a 
dry gas meter and a stopwatch, or a calibrated orifice system capable of 
measuring flow rates to within 2 percent.
    5.7.5 Performance Specification Procedure. Establish the test 
particle generator operation and verify the particle size 
microscopically. If mondispersity is to be verified by measurements at 
the beginning and the end of the run rather than by an integrated 
sample, these measurements may be made at this time.
    5.7.5.1 The cyclone cut size (D50) is defined as the 
aerodynamic diameter of a particle having a 50 percent probability of 
penetration. Determine the required cyclone flow rate at which 
D50 is 10 [micro]m. A suggested procedure is to vary the 
cyclone flow rate while keeping a constant particle size of 10 [micro]m. 
Measure the PM collected in the cyclone (mc), exit tube 
(mt), and filter (mf). Compute the cyclone 
efficiency (Ec) as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.016

    5.7.5.2 Perform three replicates and calculate the average cyclone 
efficiency as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.017

where E1, E2, and E3 are replicate 
measurements of Ec.
    5.7.5.3 Calculate the standard deviation ([sigma]) for the replicate 
measurements of Ec as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.018

if [sigma] exceeds 0.10, repeat the replicate runs.
    5.7.5.4 Using the cyclone flow rate that produces D50 for 
10 [micro]m, measure the overall efficiency of the cyclone and nozzle, 
Eo, at the particle sizes and nominal gas velocities in Table 
2 of this method using this following procedure.
    5.7.5.5 Set the air velocity in the wind tunnel to one of the 
nominal gas velocities from Table 2 of this method. Establish isokinetic 
sampling conditions and the correct flow rate through the sampler 
(cyclone and nozzle) using recycle capacity so that the D50 
is 10 [micro]m. Sample long enough to obtain 5 
percent precision on the total collected mass as determined by the 
precision and the sensitivity of the measuring technique. Determine 
separately the nozzle catch (mn), cyclone catch 
(mc), cyclone exit tube catch (mt), and collection 
filter catch (mf).
    5.7.5.6 Calculate the overall efficiency (Eo) as follows:
    [GRAPHIC] [TIFF OMITTED] TC08NO91.019
    

[[Page 452]]


    5.7.5.7 Do three replicates for each combination of gas velocities 
and particle sizes in Table 2 of this method. Calculate Eo 
for each particle size following the procedures described in this 
section for determining efficiency. Calculate the standard deviation 
([sigma]) for the replicate measurements. If [sigma] exceeds 0.10, 
repeat the replicate runs.
    5.7.6 Criteria for Acceptance. For each of the three gas stream 
velocities, plot the average Eo as a function of particle 
size on Figure 13 of this method. Draw a smooth curve for each velocity 
through all particle sizes. The curve shall be within the banded region 
for all sizes, and the average Ec for a D50 for 10 
[micro]m shall be 50 0.5 percent.
    5.8 Cyclone Calibration Procedure. The purpose of this section is to 
develop the relationship between flow rate, gas viscosity, gas density, 
and D50. This procedure only needs to be done on those 
cyclones that do not meet the design specifications in Figure 12 of this 
method.
    5.8.1 Calculate cyclone flow rate. Determine the flow rates and 
D50's for three different particle sizes between 5 [micro]m 
and 15 [micro]m, one of which shall be 10 [micro]m. All sizes must be 
within 0.5 [micro]m. For each size, use a different temperature within 
60 [deg]C (108 [deg]F) of the temperature at which the cyclone is to be 
used and conduct triplicate runs. A suggested procedure is to keep the 
particle size constant and vary the flow rate. Some of the values 
obtained in the PS tests in Section 5.7.5 may be used.
    5.8.1.1 On log-log graph paper, plot the Reynolds number (Re) on the 
abscissa, and the square root of the Stokes 50 number 
[(STK50)\1/2\] on the ordinate for each temperature. Use the 
following equations:
[GRAPHIC] [TIFF OMITTED] TC08NO91.020

[GRAPHIC] [TIFF OMITTED] TC08NO91.021

where:

Qcyc = Cyclone flow rate cm\3\/sec.
[rho] = Gas density, g/cm\3\.
dcyc = Diameter of cyclone inlet, cm.
[micro]cyc = Viscosity of gas through the cyclone, poise.
D50 = Cyclone cut size, cm.

    5.8.1.2 Use a linear regression analysis to determine the slope (m), 
and the y-intercept (b). Use the following formula to determine Q, the 
cyclone flow rate required for a cut size of 10 [micro]m.
[GRAPHIC] [TIFF OMITTED] TC08NO91.069

where:

Q = Cyclone flow rate for a cut size of 10 [micro]m, cm\3\/sec.
Ts = Stack gas temperature, [deg]K,
d = Diameter of nozzle, cm.
K1 = 4.077 x 10-3.

    5.8.2. Directions for Using Q. Refer to Section 5 of the EGR 
operators manual for directions in using this expression for Q in the 
setup calculations.

                             6. Calculations

    6.1 The EGR data reduction calculations are performed by the EGR 
reduction computer program, which is written in IBM BASIC computer 
language and is available through NTIS, Accession number PB90-500000, 
5285 Port Royal Road, Springfield, Virginia 22161. Examples of program 
inputs and outputs are shown in Figure 14 of this method.
    6.1.1 Calculations can also be done manually, as specified in Method 
5, Sections 6.3 through 6.7, and 6.9 through 6.12, with the addition of 
the following:
    6.1.2 Nomenclature.
Bc = Moisture fraction of mixed cyclone gas, by volume, 
          dimensionless.
C1 = Viscosity constant, 51.12 micropoise for [deg]K (51.05 
          micropoise for [deg] R).
C2 = Viscosity constant, 0.372 micropoise/[deg]K (0.207 
          micropoise/[deg] R).
C3 = Viscosity constant, 1.05 x 10-4 micropoise/
          [deg]K\2\ (3.24 x 10-5 micropoise/[deg] R\2\).
C4 = Viscosity constant, 53.147 micropoise/fraction 
          O2.
C5 = Viscosity constant, 74.143 micropoise/fraction 
          H2 O.
D50 = Diameter of particles having a 50 percent probability 
          of penetration, [micro]m.
f02 = Stack gas fraction O2 by volume, dry basis.
K1 = 0.3858 [deg]K/mm Hg (17.64 [deg] R/in. Hg).
Mc = Wet molecular weight of mixed gas through the 
          PM10 cyclone, g/g-mole (lb/lb-mole).

[[Page 453]]

Md = Dry molecular weight of stack gas, g/g-mole (lb/lb-
          mole).
Pbar = Barometer pressure at sampling site, mm Hg (in. Hg).
Pin1 = Gauge pressure at inlet to total LFE, mm H2 
          O (in. H2 O).
P3 = Absolute stack pressure, mm Hg (in. Hg).
Q2 = Total cyclone flow rate at wet cyclone conditions, m\3\/
          min (ft\3\/min).
Qs(std) = Total cyclone flow rate at standard conditons, 
          dscm/min (dscf/min).
Tm = Average temperature of dry gas meter, [deg]K ([deg]R).
Ts = Average stack gas temperature, [deg]K ([deg]R).
Vw(std) = Volume of water vapor in gas sample (standard 
          conditions), scm (scf).
XT = Total LFE linear calibration constant, m\3\/[(min)(mm 
          H2 O]) { ft\3\/[(min)(in. H2 O)]{time} .
YT = Total LFE linear calibration constant, dscm/min (dscf/
          min).
[Delta] PT = Pressure differential across total LFE, mm 
          H2 O, (in. H2 O).
[thetas] = Total sampling time, min.
[micro]cyc = Viscosity of mixed cyclone gas, micropoise.
[micro]LFE = Viscosity of gas laminar flow elements, 
          micropoise.
[micro]std = Viscosity of standard air, 180.1 micropoise.
    6.2 PM10 Particulate Weight. Determine the weight of 
PM10 by summing the weights obtained from Container Numbers 1 
and 3, less the acetone blank.
    6.3 Total Particulate Weight. Determine the particulate catch for PM 
greater than PM10 from the weight obtained from Container 
Number 2 less the acetone blank, and add it to the PM10 
particulate weight.
    6.4 PM10 Fraction. Determine the PM10 fraction 
of the total particulate weight by dividing the PM10 
particulate weight by the total particulate weight.
    6.5 Total Cyclone Flow Rate. The average flow rate at standard 
conditions is determined from the average pressure drop across the total 
LFE and is calculated as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.022

    The flow rate, at actual cyclone conditions, is calculated as 
follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.023

    The flow rate, at actual cyclone conditions, is calculated as 
follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.024

    6.6 Aerodynamic Cut Size. Use the following procedure to determine 
the aerodynamic cut size (D50).
    6.6.1 Determine the water fraction of the mixed gas through the 
cyclone by using the equation below.
[GRAPHIC] [TIFF OMITTED] TC08NO91.025

    6.6.2 Calculate the cyclone gas viscosity as follows:
[micro]cyc = C1 + C2 Ts + 
          C3 Ts2 + C4 f02 - 
          C5 Bc
    6.6.3 Calculate the molecular weight on a wet basis of the cyclone 
gas as follows:
Mc = Md(1 - Bc) + 18.0(Bc)
    6.6.4 If the cyclone meets the design specification in Figure 12 of 
this method, calculate the actual D50 of the cyclone for the 
run as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.026

where [beta]1 = 0.1562.

    6.6.5 If the cyclone does not meet the design specifications in 
Figure 12 of this method, then use the following equation to calculate 
D50.

[[Page 454]]

[GRAPHIC] [TIFF OMITTED] TC08NO91.027

where:

m = Slope of the calibration curve obtained in Section 5.8.2.
b = y-intercept of the calibration curve obtained in Section 5.8.2.

    6.7 Acceptable Results. Acceptability of anisokinetic variation is 
the same as Method 5, Section 6.12.
    6.7.1 If 9.0 [micro]m <=D50 <=11 [micro]m and 90 <=I 
<=110, the results are acceptable. If D50 is greater than 11 
[micro]m, the Administrator may accept the results. If D50 is 
less than 9.0 [micro]m, reject the results and repeat the test.

                             7. Bibliography

    1. Same as Bibliography in Method 5.
    2. McCain, J.D., J.W. Ragland, and A.D. Williamson. Recommended 
Methodology for the Determination of Particles Size Distributions in 
Ducted Sources, Final Report. Prepared for the California Air Resources 
Board by Southern Research Institute. May 1986.
    3. Farthing, W.E., S.S. Dawes, A.D. Williamson, J.D. McCain, R.S. 
Martin, and J.W. Ragland. Development of Sampling Methods for Source PM-
10 Emissions. Southern Research Institute for the Environmental 
Protection Agency. April 1989.
    4. Application Guide for the Source PM10 Exhaust Gas 
Recycle Sampling System, EPA/600/3-88-058.

[[Page 455]]




[[Page 456]]





[[Page 457]]





[[Page 458]]





[[Page 459]]




                EXAMPLE EMISSION GAS RECYCLE SETUP SHEET

                          VERSION 3.1 MAY 1986

TEST I.D.: SAMPLE SETUP
RUN DATE: 11/24/86
LOCATION: SOURCE SIM
OPERATOR(S): RH JB
NOZZLE DIAMETER (IN): .25
STACK CONDITIONS:
    AVERAGE TEMPERATURE (F): 200.0
    AVERAGE VELOCITY (FT/SEC): 15.0
    AMBIENT PRESSURE (IN HG): 29.92
    STACK PRESSURE (IN H20): .10
GAS COMPOSITION:
 H20 = 10.0%.......................................MD = 28.84
 O2 = 20.9%........................................MW = 27.75
 CO2 = .0%.......................................(LB/LB MOLE)

                          TARGET PRESSURE DROPS

                             TEMPERATURE (F)

DP(PTO)............             150        161        172        183        194        206        217        228
0.026..............          SAMPLE        .49        .49        .48        .47        .46        .45        .45

[[Page 460]]

 
                              TOTAL       1.90       1.90       1.91       1.92       1.92       1.92       1.93
                            RECYCLE       2.89       2.92       2.94       2.97       3.00       3.02       3.05
                              % RCL        61%        61%        62%        62%        63%        63%        63%
 
.031...............             .58        .56        .55        .55        .55        .54        .53        .52
                               1.88       1.89       1.89       1.90       1.91       1.91       1.91       1.92
                               2.71       2.74       2.77       2.80       2.82       2.85       2.88       2.90
                                57%        57%        58%        58%        59%        59%        60%        60%
 
.035...............             .67        .65        .64        .63        .62        .61       .670        .59
                               1.88       1.88       1.89       1.89       1.90       1.90       1.91       1.91
                               2.57       2.60       2.63       2.66       2.69       2.72       2.74       2.74
                                54%        55%        55%        56%        56%        57%        57%        57%
 
.039...............             .75        .74        .72        .71        .70        .69        .67        .66
                               1.87       1.88       1.88       1.89       1.89       1.90       1.90       1.91
                               2.44       2.47       2.50       2.53       2.56       2.59       2.62       2.65
                                51%        52%        52%        53%        53%        54%        54%        55%
 
                                       Figure 6. Example EGR setup sheet.
 


Barometric pressure, Pbar, in. Hg...   =      ___
Stack static pressure, Pg, in. H2 O.   =      ___
Average stack temperature, ts,         =      ___
 [deg]F.
Meter temperature, tm, [deg]F.......   =      ___
Gas analysis:
  %CO2..............................   =      ___
  %O2...............................   =      ___
  %N2 + %CO.........................   =      ___
  Fraction moisture content, Bws....   =      ___
Calibration data:
  Nozzle diameter, Dn in............   =      ___
  Pitot coefficient, Cp.............   =      ___
  [Delta]H2, in. H2O................   =      ___
Molecular weight of stack gas, dry
 basis:
  Md = 0.44
    (%CO2) + 0.32                      =    lb/lb
                                             mole
    (%O2) + 0.28
    (%N2 + %CO)
Molecular weight of stack gas, wet
 basis:
  Mw = Md (1-Bws) + 18Bws...........   =      ___  lb/lb mole
Absolute stack pressure:
  Ps = Pbar + (Pg/13.6)                =      ___  in. Hg
 

                                                   [GRAPHIC] [TIFF OMITTED] TC08NO91.071
                                                   
Desired meter orifice pressure ([Delta]H) for velocity head of stack gas 
          ([Delta]p):
          [GRAPHIC] [TIFF OMITTED] TC08NO91.072
          
    Figure 7. Example worksheet 1, meter orifice pressure head 
calculation.

Barometric pressure, Pbar, in. Hg......   =      ___
Absolute stack pressure, Ps, in. Hg....   =      ___
Average stack temperature, Ts, [deg]R..   =      ___
Meter temperature, Tm, [deg]R..........   =      ___
Molecular weight of stack gas, wet        =      ___
 basis, Md lb/lb mole.
Pressure upstream of LFE, in. Hg.......   =      0.6
Gas analysis:
  %O2..................................   =      ___
  Fraction moisture content, Bws.......   =      ___
Calibration data:
  Nozzle diameter, Dn, in..............   =      ___
  Pitot coefficient, Cp................   =      ___
  Total LFE calibration constant, Xt...   =      ___
  Total LFE calibration constant, Tt...   =      ___
Absolute pressure upstream of LFE:
  PLFE = Pbar + 0.6....................   =      ___  in. Hg
Viscosity of gas in total LFE:
  [micro]LFE = 152.418 + 0.2552 Tm +      =      ___
   3.2355 x 10-5 Tm2 + 0.53147 (%O2).

[[Page 461]]

 
Viscosity of dry stack gas:
  [micro]d = 152.418 + 0.2552 Ts +        =      ___
   3.2355 x 10-5 Ts2 + 0.53147 (%O2).
 

Constants:
[GRAPHIC] [TIFF OMITTED] TC08NO91.028

[GRAPHIC] [TIFF OMITTED] TC08NO91.029

[GRAPHIC] [TIFF OMITTED] TC08NO91.030

[GRAPHIC] [TIFF OMITTED] TC08NO91.031

[GRAPHIC] [TIFF OMITTED] TC08NO91.032

Total LFE pressure head:
[GRAPHIC] [TIFF OMITTED] TC08NO91.033

    Figure 8. Example worksheet 1, meter orifice pressure head 
calculation.

Barometric pressure, Pbar, in. Hg......   =      ___
Absolute stack pressure, Ps, in. Hg....   =      ___
Average stack temperature, Ts, [deg]R..   =      ___
Meter temperature, Tm, [deg]R..........   =      ___
Molecular weight of stack gas, dry        =      ___
 basis, Md lb/lb mole.
Viscosity of LFE gas[micro]LFE,poise...   =      ___
Absolute pressure upstream of LFE,        =      ___
 PPLEin. Hg.
Calibration data:......................
  Nozzle diameter, Dn, in..............   =      ___
  Pitot coefficient, Cp................   =      ___
Recycle LFE calibration constant, Xt      =      ___
Recycle LFE calibration constant, Yt      =      ___
 

                                             [GRAPHIC] [TIFF OMITTED] TC08NO91.034
                                             
                                             [GRAPHIC] [TIFF OMITTED] TC08NO91.035
                                             
                                             [GRAPHIC] [TIFF OMITTED] TC08NO91.036
                                             

[[Page 462]]

[GRAPHIC] [TIFF OMITTED] TC08NO91.037

[GRAPHIC] [TIFF OMITTED] TC08NO91.038

    Pressure head for recycle LFE:
    [GRAPHIC] [TIFF OMITTED] TC08NO91.039
    
    Figure 9. Example worksheet 3, recycle LFE pressure head.
    
    
Plant___________________________________________________________________
Date____________________________________________________________________
Run no._________________________________________________________________
Filter no.______________________________________________________________
Amount liquid lost during transport_____________________________________
Acetone blank volume, ml________________________________________________
Acetone wash volume, ml (2)___(3)_______________________________________
Acetone blank conc., mg/mg (Equation 5-4, Method 5)_____________________

[[Page 463]]

Acetone wash blank, mg (Equation 5-5, Method 5)_________________________

------------------------------------------------------------------------
                                                 Weight of particulate
                                                       matter, mg
               Container number               --------------------------
                                                Final     Tare    Weight
                                                weight   weight    gain
------------------------------------------------------------------------
1............................................  .......  .......  .......
3............................................  .......  .......  .......
  Total......................................  .......  .......  .......
                                                                --------
  Less acetone blank.........................  .......  .......  .......
                                                                --------
  Weight of PM10.............................  .......  .......  .......
2............................................  .......  .......  .......
                                                                --------
  Less acetone blank.........................  .......  .......  .......
                                                                --------
  Total particulate weight...................  .......  .......  .......
                                                                --------
------------------------------------------------------------------------

    Figure 11. EGR method analysis sheet.

[[Page 464]]




 Table 1--Performance Specifications for Source PM10 Cyclones and Nozzle
                              Combinations
------------------------------------------------------------------------
            Parameter                    Units           Specification
------------------------------------------------------------------------
1. Collection efficiency........  Percent...........  Such that
                                                       collection
                                                       efficiency falls
                                                       within envelope
                                                       specified by
                                                       Section 5.7.6 and
                                                       Figure 13.
2. Cyclone cut size (D50).......  [micro]m..........  10 1 [micro]m
                                                       aerodynamic
                                                       diameter.
------------------------------------------------------------------------


[[Page 465]]


                        Table 2--Particle Sizes and Nominal Gas Velocities for Efficiency
----------------------------------------------------------------------------------------------------------------
                                                                   Target gas velocities (m/sec)
                                                  --------------------------------------------------------------
           Particle size ([micro]m)\a\              7 1.0           thn-eq>1.5           thn-eq>2.5
----------------------------------------------------------------------------------------------------------------
5 0.5......................  ...................  ...................  ...................
7 0.5......................  ...................  ...................  ...................
10 0.5.....................  ...................  ...................  ...................
14 1.0.....................  ...................  ...................  ...................
20 1.0.....................  ...................  ...................  ...................
----------------------------------------------------------------------------------------------------------------
(a) Mass median aerodynamic diameter.



       Emission Gas Recycle, Data Reduction, Version 3.4 MAY 1986

    Test ID. Code: Chapel Hill 2.
    Test Location: Baghouse Outlet.
    Test Site: Chapel Hill.
    Test Date: 10/20/86.
    Operators(s): JB RH MH.

                            Entered Run Data

Temperatures:
    T(STK)..............................  251.0 F
    T(RCL)..............................  259.0 F
    T(LFE)..............................  81.0 F
    T(DGM)..............................  76.0 F
System Pressures:
    DH(ORI).............................  1.18 INWG
    DP(TOT).............................  1.91 INWG
    P(INL)..............................  12.15 INWG
    DP(RCL).............................  2.21 INWG
    DP(PTO).............................  0.06 INWG
Miscellanea:
    P(BAR)..............................  29.99 INWG
    DP(STK).............................  0.10 INWG
    V(DGM)..............................  13.744 FT3
    TIME................................  60.00 MIN
    % CO2...............................  8.00
    % O2................................  20.00
    NOZ (IN)............................  0.2500

[[Page 466]]

 
Water Content:
    Estimate............................  0.0%
      or
    Condenser...........................  7.0 ML
    Column..............................  0.0 GM
Raw Masses:
    Cyclone 1...........................  21.7 MG
    Filter..............................  11.7 MG
    Impinger Residue....................  0.0 MG
Blank Values:
    CYC Rinse...........................  0.0 MG
    Filter Holder Rinse.................  0.0 MG
    Filter Blank........................  0.0 MG
    Impinger Rinse......................  0.0 MG
 


Calibration Values:
    CP(PITOT)................................................     0.840
    DH@(ORI).................................................    10.980
    M(TOT LFE)...............................................     0.2298
    B(TOT LFE)...............................................     -.0058
    M(RCL LFE)...............................................     0.0948
    B(RCL LFE)...............................................     -.0007
    DGM GAMMA................................................     0.9940
 

                              Reduced Data

Stack Velocity (FT/SEC)........................................  15.95
Stack Gas Moisture (%).........................................   2.4
Sample Flow Rate (ACFM)........................................   0.3104
Total Flow Rate (ACFM).........................................   0.5819
Recycle Flow Rate (ACFM).......................................   0.2760
Percent Recycle................................................  46.7
Isokinetic Ratio (%)...........................................  95.1
 


----------------------------------------------------------------------------------------------------------------
                                          (Particulate)
                                       ------------------    (MG/DNCM)      (GR/ACF)     (GR/DCF)   (LB/DSCF) (X
                                          (UM)    (% <)                                                 1E6)
----------------------------------------------------------------------------------------------------------------
Cyclone 1.............................    10.15     35.8            56.6      0.01794      0.02470       3.53701
Backup Filter.........................  .......  .......            30.5      0.00968      0.01332       1.907
Particulate Total.....................  .......  .......            87.2      0.02762      0.03802       5.444
----------------------------------------------------------------------------------------------------------------
Note: Figure 14. Example inputs and outputs of the EGR reduction program.

   METHOD 201A--DETERMINATION OF PM10 AND PM2.5 
  EMISSIONS FROM STATIONARY SOURCES (Constant Sampling Rate Procedure)

                       1.0 Scope and Applicability

    1.1 Scope. The U.S. Environmental Protection Agency (U.S. EPA or 
``we'') developed this method to describe the procedures that the stack 
tester (``you'') must follow to measure filterable particulate matter 
(PM) emissions equal to or less than a nominal aerodynamic diameter of 
10 micrometers (PM10) and 2.5 micrometers (PM2.5). 
This method can be used to measure coarse particles (i.e., the 
difference between the measured PM10 concentration and the 
measured PM2.5 concentration).
    1.2 Applicability. This method addresses the equipment, preparation, 
and analysis necessary to measure filterable PM. You can use this method 
to measure filterable PM from stationary sources only. Filterable PM is 
collected in stack with this method (i.e., the method measures materials 
that are solid or liquid at stack conditions). If the gas filtration 
temperature exceeds 29.4 [deg]C (85 [deg]F), then you may use the 
procedures in this method to measure only filterable PM (material that 
does not pass through a filter or a cyclone/filter combination). If the 
gas filtration temperature exceeds 29.4 [deg]C (85 [deg]F), and you must 
measure both the filterable and condensable (material that condenses 
after passing through a filter) components of total primary (direct) PM 
emissions to the atmosphere, then you must combine the procedures in 
this method with the procedures in Method 202 of appendix M to this part 
for measuring condensable PM. However, if the gas filtration temperature 
never exceeds 29.4 [deg]C (85 [deg]F), then use of Method 202 of 
appendix M to this part is not required to measure total primary PM.
    1.3 Responsibility. You are responsible for obtaining the equipment 
and supplies you will need to use this method. You must also develop 
your own procedures for following this method and any additional 
procedures to ensure accurate sampling and analytical measurements.
    1.4 Additional Methods. To obtain results, you must have a thorough 
knowledge of the following test methods found in appendices A-1 through 
A-3 of 40 CFR part 60:
    (a) Method 1--Sample and velocity traverses for stationary sources.
    (b) Method 2--Determination of stack gas velocity and volumetric 
flow rate (Type S pitot tube).
    (c) Method 3--Gas analysis for the determination of dry molecular 
weight.
    (d) Method 4--Determination of moisture content in stack gases.
    (e) Method 5--Determination of particulate matter emissions from 
stationary sources.
    1.5 Limitations. You cannot use this method to measure emissions in 
which water droplets are present because the size separation of the 
water droplets may not be representative of the dry particle size 
released into the air. To measure filterable PM10 and 
PM2.5 in emissions where water droplets are known to exist, 
we recommend that you use Method 5 of appendix A-3 to part 60. Because 
of the temperature limit of the O-rings used in this sampling train, you 
must follow the procedures in Section 8.6.1 to test emissions from stack 
gas temperatures exceeding 205 [deg]C (400 [deg]F).

[[Page 467]]

    1.6 Conditions. You can use this method to obtain particle sizing at 
10 micrometers and or 2.5 micrometers if you sample within 80 and 120 
percent of isokinetic flow. You can also use this method to obtain total 
filterable particulate if you sample within 90 to 110 percent of 
isokinetic flow, the number of sampling points is the same as required 
by Method 5 of appendix A-3 to part 60 or Method 17 of appendix A-6 to 
part 60, and the filter temperature is within an acceptable range for 
these methods. For Method 5, the acceptable range for the filter 
temperature is generally 120 [deg]C (248 [deg]F) unless a higher or 
lower temperature is specified. The acceptable range varies depending on 
the source, control technology and applicable rule or permit condition. 
To satisfy Method 5 criteria, you may need to remove the in-stack filter 
and use an out-of-stack filter and recover the PM in the probe between 
the PM2.5 particle sizer and the filter. In addition, to 
satisfy Method 5 and Method 17 criteria, you may need to sample from 
more than 12 traverse points. Be aware that this method determines in-
stack PM10 and PM2.5 filterable emissions by 
sampling from a required maximum of 12 sample points, at a constant flow 
rate through the train (the constant flow is necessary to maintain the 
size cuts of the cyclones), and with a filter that is at the stack 
temperature. In contrast, Method 5 or Method 17 trains are operated 
isokinetically with varying flow rates through the train. Method 5 and 
Method 17 require sampling from as many as 24 sample points. Method 5 
uses an out-of-stack filter that is maintained at a constant temperature 
of 120 [deg]C (248 [deg]F). Further, to use this method in place of 
Method 5 or Method 17, you must extend the sampling time so that you 
collect the minimum mass necessary for weighing each portion of this 
sampling train. Also, if you are using this method as an alternative to 
a test method specified in a regulatory requirement (e.g., a requirement 
to conduct a compliance or performance test), then you must receive 
approval from the authority that established the regulatory requirement 
before you conduct the test.

                          2.0 Summary of Method

    2.1 Summary. To measure PM10 and PM2.5, 
extract a sample of gas at a predetermined constant flow rate through an 
in-stack sizing device. The particle-sizing device separates particles 
with nominal aerodynamic diameters of 10 micrometers and 2.5 
micrometers. To minimize variations in the isokinetic sampling 
conditions, you must establish well-defined limits. After a sample is 
obtained, remove uncombined water from the particulate, then use 
gravimetric analysis to determine the particulate mass for each size 
fraction. The original method, as promulgated in 1990, has been changed 
by adding a PM2.5 cyclone downstream of the PM10 
cyclone. Both cyclones were developed and evaluated as part of a 
conventional five-stage cascade cyclone train. The addition of a 
PM2.5 cyclone between the PM10 cyclone and the 
stack temperature filter in the sampling train supplements the 
measurement of PM10 with the measurement of PM2.5. 
Without the addition of the PM2.5 cyclone, the filterable 
particulate portion of the sampling train may be used to measure total 
and PM10 emissions. Likewise, with the exclusion of the 
PM10 cyclone, the filterable particulate portion of the 
sampling train may be used to measure total and PM2.5 
emissions. Figure 1 of Section 17 presents the schematic of the sampling 
train configured with this change.

                             3.0 Definitions

    3.1 Condensable particulate matter (CPM) means material that is 
vapor phase at stack conditions, but condenses and/or reacts upon 
cooling and dilution in the ambient air to form solid or liquid PM 
immediately after discharge from the stack. Note that all CPM is assumed 
to be in the PM2.5 size fraction.
    3.2 Constant weight means a difference of no more than 0.5 mg or one 
percent of total weight less tare weight, whichever is greater, between 
two consecutive weighings, with no less than six hours of desiccation 
time between weighings.
    3.3 Filterable particulate matter (PM) means particles that are 
emitted directly by a source as a solid or liquid at stack or release 
conditions and captured on the filter of a stack test train.
    3.4 Primary particulate matter (PM) (also known as direct PM) means 
particles that enter the atmosphere as a direct emission from a stack or 
an open source. Primary PM has two components: Filterable PM and 
condensable PM. These two PM components have no upper particle size 
limit.
    3.5 Primary PM2.5 (also known as direct PM2.5, total 
PM2.5, PM2.5, or combined filterable 
PM2.5 and condensable PM) means PM with an aerodynamic 
diameter less than or equal to 2.5 micrometers. These solid particles 
are emitted directly from an air emissions source or activity, or are 
the gaseous or vaporous emissions from an air emissions source or 
activity that condense to form PM at ambient temperatures. Direct 
PM2.5 emissions include elemental carbon, directly emitted 
organic carbon, directly emitted sulfate, directly emitted nitrate, and 
other inorganic particles (including but not limited to crustal 
material, metals, and sea salt).
    3.6 Primary PM10 (also known as direct PM10, total 
PM10, PM10, or the combination of filterable 
PM10 and condensable PM) means PM with an aerodynamic 
diameter equal to or less than 10 micrometers.

[[Page 468]]

                            4.0 Interferences

    You cannot use this method to measure emissions where water droplets 
are present because the size separation of the water droplets may not be 
representative of the dry particle size released into the air. Stacks 
with entrained moisture droplets may have water droplets larger than the 
cut sizes for the cyclones. These water droplets normally contain 
particles and dissolved solids that become PM10 and 
PM2.5 following evaporation of the water.

                               5.0 Safety

    5.1 Disclaimer. Because the performance of this method may require 
the use of hazardous materials, operations, and equipment, you should 
develop a health and safety plan to ensure the safety of your employees 
who are on site conducting the particulate emission test. Your plan 
should conform with all applicable Occupational Safety and Health 
Administration, Mine Safety and Health Administration, and Department of 
Transportation regulatory requirements. Because of the unique situations 
at some facilities and because some facilities may have more stringent 
requirements than is required by State or federal laws, you may have to 
develop procedures to conform to the plant health and safety 
requirements.

                       6.0 Equipment and Supplies

    Figure 2 of Section 17 shows details of the combined cyclone heads 
used in this method. The sampling train is the same as Method 17 of 
appendix A-6 to part 60 with the exception of the PM10 and 
PM2.5 sizing devices. The following sections describe the 
sampling train's primary design features in detail.

          6.1 Filterable Particulate Sampling Train Components.

    6.1.1 Nozzle. You must use stainless steel (316 or equivalent) or 
fluoropolymer-coated stainless steel nozzles with a sharp tapered 
leading edge. We recommend one of the 12 nozzles listed in Figure 3 of 
Section 17 because they meet design specifications when PM10 
cyclones are used as part of the sampling train. We also recommend that 
you have a large number of nozzles in small diameter increments 
available to increase the likelihood of using a single nozzle for the 
entire traverse. We recommend one of the nozzles listed in Figure 4A or 
4B of Section 17 because they meet design specifications when 
PM2.5 cyclones are used without PM10 cyclones as 
part of the sampling train.
    6.1.2 PM10 and PM2.5 Sizing Device.
    6.1.2.1 Use stainless steel (316 or equivalent) or fluoropolymer-
coated PM10 and PM2.5 sizing devices. You may use 
sizing devices constructed of high-temperature specialty metals such as 
Inconel, Hastelloy, or Haynes 230. (See also Section 8.6.1.) The sizing 
devices must be cyclones that meet the design specifications shown in 
Figures 3, 4A, 4B, 5, and 6 of Section 17. Use a caliper to verify that 
the dimensions of the PM10 and PM2.5 sizing 
devices are within 0.02 cm of the design 
specifications. Example suppliers of PM10 and 
PM2.5 sizing devices include the following:
    (a) Environmental Supply Company, Inc., 2142 E. Geer Street, Durham, 
North Carolina 27704. Telephone No.: (919) 956-9688; Fax: (919) 682-
0333.
    (b) Apex Instruments, 204 Technology Park Lane, Fuquay-Varina, North 
Carolina 27526. Telephone No.: (919) 557-7300 (phone); Fax: (919) 557-
7110.
    6.1.2.2 You may use alternative particle sizing devices if they meet 
the requirements in Development and Laboratory Evaluation of a Five-
Stage Cyclone System, EPA-600/7-78-008 (http://cfpub.epa.gov/ols).
    6.1.3 Filter Holder. Use a filter holder that is stainless steel 
(316 or equivalent). A heated glass filter holder may be substituted for 
the steel filter holder when filtration is performed out-of-stack. 
Commercial-size filter holders are available depending upon project 
requirements, including commercial stainless steel filter holders to 
support 25-, 47-, 63-, 76-, 90-, 101-, and 110-mm diameter filters. 
Commercial size filter holders contain a fluoropolymer O-ring, a 
stainless steel screen that supports the particulate filter, and a final 
fluoropolymer O-ring. Screw the assembly together and attach to the 
outlet of cyclone IV. The filter must not be compressed between the 
fluoropolymer O-ring and the filter housing.
    6.1.4 Pitot Tube. You must use a pitot tube made of heat resistant 
tubing. Attach the pitot tube to the probe with stainless steel 
fittings. Follow the specifications for the pitot tube and its 
orientation to the inlet nozzle given in Section 6.1.1.3 of Method 5 of 
appendix A-3 to part 60.
    6.1.5 Probe Extension and Liner. The probe extension must be glass- 
or fluoropolymer-lined. Follow the specifications in Section 6.1.1.2 of 
Method 5 of appendix A-3 to part 60. If the gas filtration temperature 
never exceeds 30 [deg]C (85 [deg]F), then the probe may be constructed 
of stainless steel without a probe liner and the extension is not 
recovered as part of the PM.
    6.1.6 Differential Pressure Gauge, Condensers, Metering Systems, 
Barometer, and Gas Density Determination Equipment. Follow the 
requirements in Sections 6.1.1.4 through 6.1.3 of Method 5 of appendix 
A-3 to part 60, as applicable.
    6.2 Sample Recovery Equipment.
    6.2.1 Filterable Particulate Recovery. Use the following equipment 
to quantitatively determine the amount of filterable PM recovered from 
the sampling train.
    (a) Cyclone and filter holder brushes.

[[Page 469]]

    (b) Wash bottles. Two wash bottles are recommended. Any container 
material is acceptable, but wash bottles used for sample and blank 
recovery must not contribute more than 0.1 mg of residual mass to the 
CPM measurements.
    (c) Leak-proof sample containers. Containers used for sample and 
blank recovery must not contribute more than 0.05 mg of residual mass to 
the CPM measurements.
    (d) Petri dishes. For filter samples; glass, polystyrene, or 
polyethylene, unless otherwise specified by the Administrator.
    (e) Graduated cylinders. To measure condensed water to within 1 ml 
or 0.5 g. Graduated cylinders must have subdivisions not greater than 2 
ml.
    (f) Plastic storage containers. Air-tight containers to store silica 
gel.
    6.2.2 Analysis Equipment.
    (a) Funnel. Glass or polyethylene, to aid in sample recovery.
    (b) Rubber policeman. To aid in transfer of silica gel to container; 
not necessary if silica gel is weighed in the field.
    (c) Analytical balance. Analytical balance capable of weighing at 
least 0.0001 g (0.1 mg).
    (d) Balance. To determine the weight of the moisture in the sampling 
train components, use an analytical balance accurate to 0.5 g.
    (e) Fluoropolymer beaker liners.
    7.0 Reagents, Standards, and Sampling Media
    7.1 Sample Collection. To collect a sample, you will need a filter 
and silica gel. You must also have water and crushed ice. These items 
must meet the following specifications.
    7.1.1 Filter. Use a nonreactive, nondisintegrating glass fiber, 
quartz, or polymer filter that does not a have an organic binder. The 
filter must also have an efficiency of at least 99.95 percent (less than 
0.05 percent penetration) on 0.3 micrometer dioctyl phthalate particles. 
You may use test data from the supplier's quality control program to 
document the PM filter efficiency.
    7.1.2 Silica Gel. Use an indicating-type silica gel of 6 to 16 mesh. 
You must obtain approval from the regulatory authority that established 
the requirement to use this test method to use other types of desiccants 
(equivalent or better) before you use them. Allow the silica gel to dry 
for two hours at 175 [deg]C (350 [deg]F) if it is being reused. You do 
not have to dry new silica gel if the indicator shows the silica is 
active for moisture collection.
    7.1.3 Crushed Ice. Obtain from the best readily available source.
    7.1.4 Water. Use deionized, ultra-filtered water that contains 1.0 
part per million by weight (1 milligram/liter) residual mass or less to 
recover and extract samples.
    7.2 Sample Recovery and Analytical Reagents. You will need acetone 
and anhydrous calcium sulfate for the sample recovery and analysis. 
Unless otherwise indicated, all reagents must conform to the 
specifications established by the Committee on Analytical Reagents of 
the American Chemical Society. If such specifications are not available, 
then use the best available grade. Additional information on each of 
these items is in the following paragraphs.
    7.2.1 Acetone. Use acetone that is stored in a glass bottle. Do not 
use acetone from a metal container because it will likely produce a high 
residue in the laboratory and field reagent blanks. You must use acetone 
with blank values less than 1 part per million by weight residue. 
Analyze acetone blanks prior to field use to confirm low blank values. 
In no case shall a blank value of greater than 0.0001 percent (1 part 
per million by weight) of the weight of acetone used in sample recovery 
be subtracted from the sample weight (i.e., the maximum blank correction 
is 0.1 mg per 100 g of acetone used to recover samples).
    7.2.2 Particulate Sample Desiccant. Use indicating-type anhydrous 
calcium sulfate to desiccate samples prior to weighing.

       8.0 Sample Collection, Preservation, Storage, and Transport

    8.1 Qualifications. This is a complex test method. To obtain 
reliable results, you should be trained and experienced with in-stack 
filtration systems (such as cyclones, impactors, and thimbles) and 
impinger and moisture train systems.
    8.2 Preparations. Follow the pretest preparation instructions in 
Section 8.1 of Method 5 of appendix A-3 to part 60.
    8.3 Site Setup. You must complete the following to properly set up 
for this test:
    (a) Determine the sampling site location and traverse points.
    (b) Calculate probe/cyclone blockage.
    (c) Verify the absence of cyclonic flow.
    (d) Complete a preliminary velocity profile and select a nozzle(s) 
and sampling rate.
    8.3.1 Sampling Site Location and Traverse Point Determination. 
Follow the standard procedures in Method 1 of appendix A-1 to part 60 to 
select the appropriate sampling site. Choose a location that maximizes 
the distance from upstream and downstream flow disturbances.
    (a) Traverse points. The required maximum number of total traverse 
points at any location is 12, as shown in Figure 7 of Section 17. You 
must prevent the disturbance and capture of any solids accumulated on 
the inner wall surfaces by maintaining a 1-inch distance from the stack 
wall (0.5 inch for sampling locations less than 36.4 inches in diameter 
with the pitot tube and 32.4 inches without the pitot tube). During 
sampling, when the PM2.5 cyclone is used without the 
PM10, traverse points closest to the stack walls may not be 
reached because the inlet

[[Page 470]]

to a PM2.5 cyclone is located approximately 2.75 inches from 
the end of the cyclone. For these cases, you may collect samples using 
the procedures in Section 11.3.2.2 of Method 1 of appendix A-3 to part 
60. You must use the traverse point closest to the unreachable sampling 
points as replacement for the unreachable points. You must extend the 
sampling time at the replacement sampling point to include the duration 
of the unreachable traverse points.
    (b) Round or rectangular duct or stack. If a duct or stack is round 
with two ports located 90[deg] apart, use six sampling points on each 
diameter. Use a 3x4 sampling point layout for rectangular ducts or 
stacks. Consult with the Administrator to receive approval for other 
layouts before you use them.
    (c) Sampling ports. You must determine if the sampling ports can 
accommodate the in-stack cyclones used in this method. You may need 
larger diameter sampling ports than those used by Method 5 of appendix 
A-3 to part 60 or Method 17 of appendix A-6 to part 60 for total 
filterable particulate sampling. When you use nozzles smaller than 0.16 
inch in diameter and either a PM10 or a combined 
PM10 and PM2.5 sampling apparatus, the sampling 
port diameter may need to be six inches in diameter to accommodate the 
entire apparatus because the conventional 4-inch diameter port may be 
too small due to the combined dimension of the PM10 cyclone 
and the nozzle extending from the cyclone, which will likely exceed the 
internal diameter of the port. A 4-inch port should be adequate for the 
single PM2.5 sampling apparatus. However, do not use the 
conventional 4-inch diameter port in any circumstances in which the 
combined dimension of the cyclone and the nozzle extending from the 
cyclone exceeds the internal diameter of the port. (Note: If the port 
nipple is short, you may be able to ``hook'' the sampling head through a 
smaller port into the duct or stack.)
    8.3.2 Probe/Cyclone Blockage Calculations. Follow the procedures in 
the next two sections, as appropriate.
    8.3.2.1 Ducts with diameters greater than 36.4 inches. Based on 
commercially available cyclone assemblies for this procedure, ducts with 
diameters greater than 36.4 inches have blockage effects less than three 
percent, as illustrated in Figure 8 of Section 17. You must minimize the 
blockage effects of the combination of the in-stack nozzle/cyclones, 
pitot tube, and filter assembly that you use by keeping the cross-
sectional area of the assembly at three percent or less of the cross-
sectional area of the duct.
    8.3.2.2 Ducts with diameters between 25.7 and 36.4 inches. Ducts 
with diameters between 25.7 and 36.4 inches have blockage effects 
ranging from three to six percent, as illustrated in Figure 8 of Section 
17. Therefore, when you conduct tests on these small ducts, you must 
adjust the observed velocity pressures for the estimated blockage factor 
whenever the combined sampling apparatus blocks more than three percent 
of the stack or duct (see Sections 8.7.2.2 and 8.7.2.3 on the probe 
blockage factor and the final adjusted velocity pressure, respectively). 
(Note: Valid sampling with the combined PM2.5/PM10 
cyclones cannot be performed with this method if the average stack 
blockage from the sampling assembly is greater than six percent, i.e., 
the stack diameter is less than 26.5 inches.)
    8.3.3 Cyclonic Flow. Do not use the combined cyclone sampling head 
at sampling locations subject to cyclonic flow. Also, you must follow 
procedures in Method 1 of appendix A-1 to part 60 to determine the 
presence or absence of cyclonic flow and then perform the following 
calculations:
    (a) As per Section 11.4 of Method 1 of appendix A-1 to part 60, find 
and record the angle that has a null velocity pressure for each traverse 
point using an S-type pitot tube.
    (b) Average the absolute values of the angles that have a null 
velocity pressure. Do not use the sampling location if the average 
absolute value exceeds 20[deg]. (Note: You can minimize the effects of 
cyclonic flow conditions by moving the sampling location, placing gas 
flow straighteners upstream of the sampling location, or applying a 
modified sampling approach as described in EPA Guideline Document GD-
008, Particulate Emissions Sampling in Cyclonic Flow. You may need to 
obtain an alternate method approval from the regulatory authority that 
established the requirement to use this test method prior to using a 
modified sampling approach.)
    8.3.4 Preliminary Velocity Profile. Conduct a preliminary velocity 
traverse by following Method 2 of appendix A-1 to part 60 velocity 
traverse procedures. The purpose of the preliminary velocity profile is 
to determine all of the following:
    (a) The gas sampling rate for the combined probe/cyclone sampling 
head in order to meet the required particle size cut.
    (b) The appropriate nozzle to maintain the required gas sampling 
rate for the velocity pressure range and isokinetic range. If the 
isokinetic range cannot be met (e.g., batch processes, extreme process 
flow or temperature variation), void the sample or use methods subject 
to the approval of the Administrator to correct the data. The acceptable 
variation from isokinetic sampling is 80 to 120 percent and no more than 
100  21 percent (2 out of 12 or 5 out of 24) 
sampling points outside of this criteria.
    (c) The necessary sampling duration to obtain sufficient particulate 
catch weights.
    8.3.4.1 Preliminary traverse. You must use an S-type pitot tube with 
a conventional

[[Page 471]]

thermocouple to conduct the traverse. Conduct the preliminary traverse 
as close as possible to the anticipated testing time on sources that are 
subject to hour-by-hour gas flow rate variations of approximately  20 percent and/or gas temperature variations of 
approximately  28 [deg]C ( 
50 [deg]F). (Note: You should be aware that these variations can cause 
errors in the cyclone cut diameters and the isokinetic sampling 
velocities.)
    8.3.4.2 Velocity pressure range. Insert the S-type pitot tube at 
each traverse point and record the range of velocity pressures measured 
on data form in Method 2 of appendix A-1 to part 60. You will use this 
later to select the appropriate nozzle.
    8.3.4.3 Initial gas stream viscosity and molecular weight. Determine 
the average gas temperature, average gas oxygen content, average carbon 
dioxide content, and estimated moisture content. You will use this 
information to calculate the initial gas stream viscosity (Equation 3) 
and molecular weight (Equations 1 and 2). (Note: You must follow the 
instructions outlined in Method 4 of appendix A-3 to part 60 or 
Alternative Moisture Measurement Method Midget Impingers (ALT-008) to 
estimate the moisture content. You may use a wet bulb-dry bulb 
measurement or hand-held hygrometer measurement to estimate the moisture 
content of sources with gas temperatures less than 71 [deg]C (160 
[deg]F).)
    8.3.4.4 Approximate PM concentration in the gas stream. Determine 
the approximate PM concentration for the PM2.5 and the 
PM2.5 to PM10 components of the gas stream through 
qualitative measurements or estimates from precious stack particulate 
emissions tests. Having an idea of the particulate concentration in the 
gas stream is not essential but will help you determine the appropriate 
sampling time to acquire sufficient PM weight for better accuracy at the 
source emission level. The collectible PM weight requirements depend 
primarily on the types of filter media and weighing capabilities that 
are available and needed to characterize the emissions. Estimate the 
collectible PM concentrations in the greater than 10 micrometer, less 
than or equal to 10 micrometers and greater than 2.5 micrometers, and 
less than or equal to 2.5 micrometer size ranges. Typical PM 
concentrations are listed in Table 1 of Section 17. Additionally, 
relevant sections of AP-42, Compilation of Air Pollutant Emission 
Factors, may contain particle size distributions for processes 
characterized in those sections, and appendix B2 of AP-42 contains 
generalized particle size distributions for nine industrial process 
categories (e.g., stationary internal combustion engines firing gasoline 
or diesel fuel, calcining of aggregate or unprocessed ores). The 
generalized particle size distributions can be used if source-specific 
particle size distributions are unavailable. Appendix B2 of AP-42 also 
contains typical collection efficiencies of various particulate control 
devices and example calculations showing how to estimate uncontrolled 
total particulate emissions, uncontrolled size-specific emissions, and 
controlled size-specific particulate emissions. (http://www.epa.gov/
ttnchie1/ap42.)
    8.4 Pre-test Calculations. You must perform pre-test calculations to 
help select the appropriate gas sampling rate through cyclone I 
(PM10) and cyclone IV (PM2.5). Choosing the 
appropriate sampling rate will allow you to maintain the appropriate 
particle cut diameters based upon preliminary gas stream measurements, 
as specified in Table 2 of Section 17.
    8.4.1 Gas Sampling Rate. The gas sampling rate is defined by the 
performance curves for both cyclones, as illustrated in Figure 10 of 
Section 17. You must use the calculations in Section 8.5 to achieve the 
appropriate cut size specification for each cyclone. The optimum gas 
sampling rate is the overlap zone defined as the range below the cyclone 
IV 2.25 micrometer curve down to the cyclone I 11.0 micrometer curve 
(area between the two dark, solid lines in Figure 10 of Section 17).
    8.4.2 Choosing the Appropriate Sampling Rate. You must select a gas 
sampling rate in the middle of the overlap zone (discussed in Section 
8.4.1), as illustrated in Figure 10 of Section 17, to maximize the 
acceptable tolerance for slight variations in flow characteristics at 
the sampling location. The overlap zone is also a weak function of the 
gas composition. (Note: The acceptable range is limited, especially for 
gas streams with temperatures less than approximately 100 [deg]F. At 
lower temperatures, it may be necessary to perform the PM10 
and PM2.5 separately in order to meet the necessary particle 
size criteria shown in Table 2 of Section 17.)
    8.5 Test Calculations. You must perform all of the calculations in 
Table 3 of Section 17 and the calculations described in Sections 8.5.1 
through 8.5.5.
    8.5.1 Assumed Reynolds Number. You must select an assumed Reynolds 
number (Nre) using Equation 10 and an estimated sampling rate 
or from prior experience under the stack conditions determined using 
Methods 1 through 4 to part 60. You will perform initial test 
calculations based on an assumed Nre for the test to be 
performed. You must verify the assumed Nre by substituting 
the sampling rate (Qs) calculated in Equation 7 into Equation 
10. Then use Table 5 of Section 17 to determine if the Nre 
used in Equation 5 was correct.
    8.5.2 Final Sampling Rate. Recalculate the final Qs if 
the assumed Nre used in your initial calculation is not 
correct. Use Equation 7 to recalculate the optimum Qs.
    8.5.3 Meter Box [Delta]H. Use Equation 11 to calculate the meter box 
orifice pressure drop

[[Page 472]]

([Delta]H) after you calculate the optimum sampling rate and confirm the 
Nre. (Note: The stack gas temperature may vary during the 
test, which could affect the sampling rate. If the stack gas temperature 
varies, you must make slight adjustments in the meter box [Delta]H to 
maintain the correct constant cut diameters. Therefore, use Equation 11 
to recalculate the [Delta]H values for 50 [deg]F above and below the 
stack temperature measured during the preliminary traverse (see Section 
8.3.4.1), and document this information in Table 4 of Section 17.)
    8.5.4 Choosing a Sampling Nozzle. Select one or more nozzle sizes to 
provide for near isokinetic sampling rate (see Section 1.6). This will 
also minimize an isokinetic sampling error for the particles at each 
point. First calculate the mean stack gas velocity (vs) using 
Equation 13. See Section 8.7.2 for information on correcting for 
blockage and use of different pitot tube coefficients. Then use Equation 
14 to calculate the diameter (D) of a nozzle that provides for 
isokinetic sampling at the mean vs at flow Qs. 
From the available nozzles one size smaller and one size larger than 
this diameter, D, select the most appropriate nozzle. Perform the 
following steps for the selected nozzle.
    8.5.4.1 Minimum/maximum nozzle/stack velocity ratio. Use Equation 15 
to determine the velocity of gas in the nozzle. Use Equation 16 to 
calculate the minimum nozzle/stack velocity ratio (Rmin). Use 
Equation 17 to calculate the maximum nozzle/stack velocity ratio 
(Rmax).
    8.5.4.2 Minimum gas velocity. Use Equation 18 to calculate the 
minimum gas velocity (vmin) if Rmin is an 
imaginary number (negative value under the square root function) or if 
Rmin is less than 0.5. Use Equation 19 to calculate 
vmin if Rmin is =0.5.
    8.5.4.3 Maximum stack velocity. Use Equation 20 to calculate the 
maximum stack velocity (vmax) if Rmax is less than 
1.5. Use Equation 21 to calculate the stack velocity if Rmax 
is =1.5.
    8.5.4.4 Conversion of gas velocities to velocity pressure. Use 
Equation 22 to convert vmin to minimum velocity pressure, 
[Delta]pmin. Use Equation 23 to convert vmax to 
maximum velocity pressure, [Delta]pmax.
    8.5.4.5 Comparison to observed velocity pressures. Compare minimum 
and maximum velocity pressures with the observed velocity pressures at 
all traverse points during the preliminary test (see Section 8.3.4.2).
    8.5.5 Optimum Sampling Nozzle. The nozzle you selected is 
appropriate if all the observed velocity pressures during the 
preliminary test fall within the range of the [Delta]pmin and 
[Delta]pmax. Make sure the following requirements are met 
then follow the procedures in Sections 8.5.5.1 and 8.5.5.2.
    (a) Choose an optimum nozzle that provides for isokinetic sampling 
conditions as close to 100 percent as possible. This is prudent because 
even if there are slight variations in the gas flow rate, gas 
temperature, or gas composition during the actual test, you have the 
maximum assurance of satisfying the isokinetic criteria. Generally, one 
of the two candidate nozzles selected will be closer to optimum (see 
Section 8.5.4).
    (b) When testing is for PM2.5 only, you are allowed a 16 
percent failure rate, rounded to the nearest whole number, of sampling 
points that are outside the range of the [Delta]pmin and 
[Delta]pmax. If the coarse fraction for PM10 
determination is included, you are allowed only an eight percent failure 
rate of the sampling points, rounded to the nearest whole number, 
outside the [Delta]pmin and [Delta]pmax.
    8.5.5.1 Precheck. Visually check the selected nozzle for dents 
before use.
    8.5.5.2 Attach the pre-selected nozzle. Screw the pre-selected 
nozzle onto the main body of cyclone I using fluoropolymer tape. Use a 
union and cascade adaptor to connect the cyclone IV inlet to the outlet 
of cyclone I (see Figure 2 of Section 17).
    8.6 Sampling Train Preparation. A schematic of the sampling train 
used in this method is shown in Figure 1 of Section 17. First, assemble 
the train and complete the leak check on the combined cyclone sampling 
head and pitot tube. Use the following procedures to prepare the 
sampling train. (Note: Do not contaminate the sampling train during 
preparation and assembly. Keep all openings, where contamination can 
occur, covered until just prior to assembly or until sampling is about 
to begin.)
    8.6.1 Sampling Head and Pitot Tube. Assemble the combined cyclone 
train. The O-rings used in the train have a temperature limit of 
approximately 205 [deg]C (400 [deg]F). Use cyclones with stainless steel 
sealing rings for stack temperatures above 205 [deg]C (400 [deg]F) up to 
260 [deg]C (500 [deg]F). You must also keep the nozzle covered to 
protect it from nicks and scratches. This method may not be suitable for 
sources with stack gas temperatures exceeding 260 [deg]C (500 [deg]F) 
because the threads of the cyclone components may gall or seize, thus 
preventing the recovery of the collected PM and rendering the cyclone 
unusable for subsequent use. You may use stainless steel cyclone 
assemblies constructed with bolt-together rather than screw-together 
assemblies at temperatures up to 538 [deg]C (1,000 [deg]F). You must use 
``break-away'' or expendable stainless steel bolts that can be over-
torqued and broken if necessary to release cyclone closures, thus 
allowing you to recover PM without damaging the cyclone flanges or 
contaminating the samples. You may need to use specialty metals to 
achieve reliable particulate mass measurements above 538 [deg]C (1,000 
[deg]F). The method can be used at temperatures up to 1,371 [deg]C 
(2,500 [deg]F) using specially constructed high-temperature stainless 
steel alloys (Hastelloy or Haynes 230)

[[Page 473]]

with bolt-together closures using break-away bolts.
    8.6.2 Filterable Particulate Filter Holder and Pitot Tube. Attach 
the pre-selected filter holder to the end of the combined cyclone 
sampling head (see Figure 2 of Section 17). Attach the S-type pitot tube 
to the combined cyclones after the sampling head is fully attached to 
the end of the probe. (Note: The pitot tube tip must be mounted slightly 
beyond the combined head cyclone sampling assembly and at least one inch 
off the gas flow path into the cyclone nozzle. This is similar to the 
pitot tube placement in Method 17 of appendix A-6 to part 60.) Securely 
fasten the sensing lines to the outside of the probe to ensure proper 
alignment of the pitot tube. Provide unions on the sensing lines so that 
you can connect and disconnect the S-type pitot tube tips from the 
combined cyclone sampling head before and after each run. Calibrate the 
pitot tube on the sampling head according to the most current ASTM 
International D3796 because the cyclone body is a potential source flow 
disturbance and will change the pitot coefficient value from the 
baseline (isolated tube) value.
    8.6.3 Filter. You must number and tare the filters before use. To 
tare the filters, desiccate each filter at 20 5.6 
[deg]C (68 10 [deg]F) and ambient pressure for at 
least 24 hours and weigh at intervals of at least six hours to a 
constant weight. (See Section 3.0 for a definition of constant weight.) 
Record results to the nearest 0.1 mg. During each weighing, the filter 
must not be exposed to the laboratory atmosphere for longer than two 
minutes and a relative humidity above 50 percent. Alternatively, the 
filters may be oven-dried at 104 [deg]C (220 [deg]F) for two to three 
hours, desiccated for two hours, and weighed. Use tweezers or clean 
disposable surgical gloves to place a labeled (identified) and pre-
weighed filter in the filter holder. You must center the filter and 
properly place the gasket so that the sample gas stream will not 
circumvent the filter. The filter must not be compressed between the 
gasket and the filter housing. Check the filter for tears after the 
assembly is completed. Then screw or clamp the filter housing together 
to prevent the seal from leaking.
    8.6.4 Moisture Trap. If you are measuring only filterable 
particulate (or you are sure that the gas filtration temperature will be 
maintained below 30 [deg]C (85 [deg]F)), then an empty modified 
Greenburg Smith impinger followed by an impinger containing silica gel 
is required. Alternatives described in Method 5 of appendix A-3 to part 
60 may also be used to collect moisture that passes through the ambient 
filter. If you are measuring condensable PM in combination with this 
method, then follow the procedures in Method 202 of appendix M of this 
part for moisture collection.
    8.6.5 Leak Check. Use the procedures outlined in Section 8.4 of 
Method 5 of appendix A-3 to part 60 to leak check the entire sampling 
system. Specifically perform the following procedures:
    8.6.5.1 Sampling train. You must pretest the entire sampling train 
for leaks. The pretest leak check must have a leak rate of not more than 
0.02 actual cubic feet per minute or four percent of the average sample 
flow during the test run, whichever is less. Additionally, you must 
conduct the leak check at a vacuum equal to or greater than the vacuum 
anticipated during the test run. Enter the leak check results on the 
analytical data sheet (see Section 11.1) for the specific test. (Note: 
Do not conduct a leak check during port changes.)
    8.6.5.2 Pitot tube assembly. After you leak check the sample train, 
perform a leak check of the pitot tube assembly. Follow the procedures 
outlined in Section 8.4.1 of Method 5 of appendix A-3 to part 60.
    8.6.6 Sampling Head. You must preheat the combined sampling head to 
the stack temperature of the gas stream at the test location (28 [deg]C, 50 [deg]F). This will 
heat the sampling head and prevent moisture from condensing from the 
sample gas stream.
    8.6.6.1 Warmup. You must complete a passive warmup (of 30-40 min) 
within the stack before the run begins to avoid internal condensation.
    8.6.6.2 Shortened warmup. You can shorten the warmup time by 
thermostated heating outside the stack (such as by a heat gun). Then 
place the heated sampling head inside the stack and allow the 
temperature to equilibrate.
    8.7 Sampling Train Operation. Operate the sampling train the same as 
described in Section 4.1.5 of Method 5 of appendix A-3 to part 60, but 
use the procedures in this section for isokinetic sampling and flow rate 
adjustment. Maintain the flow rate calculated in Section 8.4.1 
throughout the run, provided the stack temperature is within 28 [deg]C 
(50 [deg]F) of the temperature used to calculate [Delta]H. If stack 
temperatures vary by more than 28 [deg]C (50 [deg]F), use the 
appropriate [Delta]H value calculated in Section 8.5.3. Determine the 
minimum number of traverse points as in Figure 7 of Section 17. 
Determine the minimum total projected sampling time based on achieving 
the data quality objectives or emission limit of the affected facility. 
We recommend that you round the number of minutes sampled at each point 
to the nearest 15 seconds. Perform the following procedures:
    8.7.1 Sample Point Dwell Time. You must calculate the flow rate-
weighted dwell time (that is, sampling time) for each sampling point to 
ensure that the overall run provides a velocity-weighted average that is 
representative of the entire gas stream. Vary

[[Page 474]]

the dwell time at each traverse point proportionately with the point 
velocity. Calculate the dwell time at each of the traverse points using 
Equation 24. You must use the data from the preliminary traverse to 
determine the average velocity pressure ([Delta]pavg). You 
must use the velocity pressure measured during the sampling run to 
determine the velocity pressure at each point ([Delta]pn). 
Here, Ntp equals the total number of traverse points. Each 
traverse point must have a dwell time of at least two minutes.
    8.7.2 Adjusted Velocity Pressure. When selecting your sampling 
points using your preliminary velocity traverse data, your preliminary 
velocity pressures must be adjusted to take into account the increase in 
velocity due to blockage. Also, you must adjust your preliminary 
velocity data for differences in pitot tube coefficients. Use the 
following instructions to adjust the preliminary velocity pressure.
    8.7.2.1 Different pitot tube coefficient. You must use Equation 25 
to correct the recorded preliminary velocity pressures if the pitot tube 
mounted on the combined cyclone sampling head has a different pitot tube 
coefficient than the pitot tube used during the preliminary velocity 
traverse (see Section 8.3.4).
    8.7.2.2 Probe blockage factor. You must use Equation 26 to calculate 
an average probe blockage correction factor (bf) if the 
diameter of your stack or duct is between 25.7 and 36.4 inches for the 
combined PM2.5/PM10 sampling head and pitot and 
between 18.8 and 26.5 inches for the PM2.5 cyclone and pitot. 
A probe blockage factor is calculated because of the flow blockage 
caused by the relatively large cross-sectional area of the cyclone 
sampling head, as discussed in Section 8.3.2.2 and illustrated in 
Figures 8 and 9 of Section 17. You must determine the cross-sectional 
area of the cyclone head you use and determine its stack blockage 
factor. (Note: Commercially-available sampling heads (including the 
PM10 cyclone, PM2.5 cyclone, pitot and filter 
holder) have a projected area of approximately 31.2 square inches when 
oriented into the gas stream.) As the probe is moved from the outermost 
to the innermost point, the amount of blockage that actually occurs 
ranges from approximately 13 square inches to the full 31.2 square 
inches plus the blockage caused by the probe extension. The average 
cross-sectional area blocked is 22 square inches.
    8.7.2.3 Final adjusted velocity pressure. Calculate the final 
adjusted velocity pressure ([Delta]ps2) using Equation 27. 
(Note: Figures 8 and 9 of Section 17 illustrate that the blockage effect 
of the combined PM10, PM2.5 cyclone sampling head, 
and pitot tube increases rapidly below stack diameters of 26.5 inches. 
Therefore, the combined PM10, PM2.5 filter 
sampling head and pitot tube is not applicable for stacks with a 
diameter less than 26.5 inches because the blockage is greater than six 
percent. For stacks with a diameter less than 26.5 inches, 
PM2.5 particulate measurements may be possible using only a 
PM2.5 cyclone, pitot tube, and in-stack filter. If the 
blockage exceeds three percent but is less than six percent, you must 
follow the procedures outlined in Method 1A of appendix A-1 to part 60 
to conduct tests. You must conduct the velocity traverse downstream of 
the sampling location or immediately before the test run.
    8.7.3 Sample Collection. Collect samples the same as described in 
Section 4.1.5 of Method 5 of appendix A-3 to part 60, except use the 
procedures in this section for isokinetic sampling and flow rate 
adjustment. Maintain the flow rate calculated in Section 8.5 throughout 
the run, provided the stack temperature is within 28 [deg]C (50 [deg]F) 
of the temperature used to calculate [Delta]H. If stack temperatures 
vary by more than 28 [deg]C (50 [deg]F), use the appropriate [Delta]H 
value calculated in Section 8.5.3. Calculate the dwell time at each 
traverse point as in Equation 24. In addition to these procedures, you 
must also use running starts and stops if the static pressure at the 
sampling location is less than minus 5 inches water column. This 
prevents back pressure from rupturing the sample filter. If you use a 
running start, adjust the flow rate to the calculated value after you 
perform the leak check (see Section 8.4).
    8.7.3.1 Level and zero manometers. Periodically check the level and 
zero point of the manometers during the traverse. Vibrations and 
temperature changes may cause them to drift.
    8.7.3.2 Portholes. Clean the portholes prior to the test run. This 
will minimize the chance of collecting deposited material in the nozzle.
    8.7.3.3 Sampling procedures. Verify that the combined cyclone 
sampling head temperature is at stack temperature. You must maintain the 
temperature of the cyclone sampling head within 10 
[deg]C (18 [deg]F) of the stack temperature. 
(Note: For many stacks, portions of the cyclones and filter will be 
external to the stack during part of the sampling traverse. Therefore, 
you must heat and/or insulate portions of the cyclones and filter that 
are not within the stack in order to maintain the sampling head 
temperature at the stack temperature. Maintaining the temperature will 
ensure proper particle sizing and prevent condensation on the walls of 
the cyclones.) To begin sampling, remove the protective cover from the 
nozzle. Position the probe at the first sampling point with the nozzle 
pointing directly into the gas stream. Immediately start the pump and 
adjust the flow to calculated isokinetic conditions. Ensure the probe/
pitot tube assembly is leveled. (Note: When the probe is in position, 
block off the openings around the probe

[[Page 475]]

and porthole to prevent unrepresentative dilution of the gas stream. 
Take care to minimize contamination from material used to block the flow 
or insulate the sampling head during collection at the first sampling 
point.)
    (a) Traverse the stack cross-section, as required by Method 1 of 
appendix A-1 to part 60, with the exception that you are only required 
to perform a 12-point traverse. Do not bump the cyclone nozzle into the 
stack walls when sampling near the walls or when removing or inserting 
the probe through the portholes. This will minimize the chance of 
extracting deposited materials.
    (b) Record the data required on the field test data sheet for each 
run. Record the initial dry gas meter reading. Then take dry gas meter 
readings at the following times: the beginning and end of each sample 
time increment; when changes in flow rates are made; and when sampling 
is halted. Compare the velocity pressure measurements (Equations 22 and 
23) with the velocity pressure measured during the preliminary traverse. 
Keep the meter box [Delta]H at the value calculated in Section 8.5.3 for 
the stack temperature that is observed during the test. Record all 
point-by-point data and other source test parameters on the field test 
data sheet. Do not leak check the sampling system during port changes.
    (c) Maintain flow until the sampling head is completely removed from 
the sampling port. You must restart the sampling flow prior to inserting 
the sampling head into the sampling port during port changes.
    (d) Maintain the flow through the sampling system at the last 
sampling point. At the conclusion of the test, remove the pitot tube and 
combined cyclone sampling head from the stack while the train is still 
operating (running stop). Make sure that you do not scrape the pitot 
tube or the combined cyclone sampling head against the port or stack 
walls. Then stop the pump and record the final dry gas meter reading and 
other test parameters on the field test data sheet. (Note: After you 
stop the pump, make sure you keep the combined cyclone head level to 
avoid tipping dust from the cyclone cups into the filter and/or down-
comer lines.)
    8.7.4 Process Data. You must document data and information on the 
process unit tested, the particulate control system used to control 
emissions, any non-particulate control system that may affect 
particulate emissions, the sampling train conditions, and weather 
conditions. Record the site barometric pressure and stack pressure on 
the field test data sheet. Discontinue the test if the operating 
conditions may cause non-representative particulate emissions.
    8.7.4.1 Particulate control system data. Use the process and control 
system data to determine whether representative operating conditions 
were maintained throughout the testing period.
    8.7.4.2 Sampling train data. Use the sampling train data to confirm 
that the measured particulate emissions are accurate and complete.
    8.7.5 Sample Recovery. First remove the sampling head (combined 
cyclone/filter assembly) from the train probe. After the sample head is 
removed, perform a post-test leak check of the probe and sample train. 
Then recover the components from the cyclone/filter. Refer to the 
following sections for more detailed information.
    8.7.5.1 Remove sampling head. After cooling and when the probe can 
be safely handled, wipe off all external surfaces near the cyclone 
nozzle and cap the inlet to the cyclone to prevent PM from entering the 
assembly. Remove the combined cyclone/filter sampling head from the 
probe. Cap the outlet of the filter housing to prevent PM from entering 
the assembly.
    8.7.5.2 Leak check probe/sample train assembly (post-test). Leak 
check the remainder of the probe and sample train assembly (including 
meter box) after removing the combined cyclone head/filter. You must 
conduct the leak rate at a vacuum equal to or greater than the maximum 
vacuum achieved during the test run. Enter the results of the leak check 
onto the field test data sheet. If the leak rate of the sampling train 
(without the combined cyclone sampling head) exceeds 0.02 actual cubic 
feet per minute or four percent of the average sampling rate during the 
test run (whichever is less), the run is invalid and must be repeated.
    8.7.5.3 Weigh or measure the volume of the liquid collected in the 
water collection impingers and silica trap. Measure the liquid in the 
first impingers to within 1 ml using a clean graduated cylinder or by 
weighing it to within 0.5 g using a balance. Record the volume of the 
liquid or weight of the liquid present to be used to calculate the 
moisture content of the effluent gas.
    8.7.5.4 Weigh the silica impinger. If a balance is available in the 
field, weigh the silica impinger to within 0.5 g. Note the color of the 
indicating silica gel in the last impinger to determine whether it has 
been completely spent and make a notation of its condition. If you are 
measuring CPM in combination with this method, the weight of the silica 
gel can be determined before or after the post-test nitrogen purge is 
complete (See Section 8.5.3 of Method 202 of appendix M to this part).
    8.7.5.5 Recovery of PM. Recovery involves the quantitative transfer 
of particles in the following size range: greater than 10 micrometers; 
less than or equal to 10 micrometers but greater than 2.5 micrometers; 
and less than or equal to 2.5 micrometers. You must use a nylon or 
fluoropolymer brush and an acetone rinse to recover particles from the

[[Page 476]]

combined cyclone/filter sampling head. Use the following procedures for 
each container:
    (a) Container 1, Less than or equal to PM2.5 micrometer 
filterable particulate. Use tweezers and/or clean disposable surgical 
gloves to remove the filter from the filter holder. Place the filter in 
the Petri dish that you labeled with the test identification and 
Container 1. Using a dry brush and/or a sharp-edged blade, carefully 
transfer any PM and/or filter fibers that adhere to the filter holder 
gasket or filter support screen to the Petri dish. Seal the container. 
This container holds particles less than or equal to 2.5 micrometers 
that are caught on the in-stack filter. (Note: If the test is conducted 
for PM10 only, then Container 1 would be for less than or 
equal to PM10 micrometer filterable particulate.)
    (b) Container 2, Greater than PM10 micrometer filterable 
particulate. Quantitatively recover the PM from the cyclone I cup and 
brush cleaning and acetone rinses of the cyclone cup, internal surface 
of the nozzle, and cyclone I internal surfaces, including the outside 
surface of the downcomer line. Seal the container and mark the liquid 
level on the outside of the container you labeled with test 
identification and Container 2. You must keep any dust found on the 
outside of cyclone I and cyclone nozzle external surfaces out of the 
sample. This container holds PM greater than 10 micrometers.
    (c) Container 3, Filterable particulate less than or equal to 10 
micrometer and greater than 2.5 micrometers. Place the solids from 
cyclone cup IV and the acetone (and brush cleaning) rinses of the 
cyclone I turnaround cup (above inner downcomer line), inside of the 
downcomer line, and interior surfaces of cyclone IV into Container 3. 
Seal the container and mark the liquid level on the outside of the 
container you labeled with test identification and Container 3. This 
container holds PM less than or equal to 10 micrometers but greater than 
2.5 micrometers.
    (d) Container 4, Less than or equal to PM2.5 micrometers acetone 
rinses of the exit tube of cyclone IV and front half of the filter 
holder. Place the acetone rinses (and brush cleaning) of the exit tube 
of cyclone IV and the front half of the filter holder in container 4. 
Seal the container and mark the liquid level on the outside of the 
container you labeled with test identification and Container 4. This 
container holds PM that is less than or equal to 2.5 micrometers.
    (e) Container 5, Cold impinger water. If the water from the cold 
impinger used for moisture collection has been weighed in the field, it 
can be discarded. Otherwise, quantitatively transfer liquid from the 
cold impinger that follows the ambient filter into a clean sample bottle 
(glass or plastic). Mark the liquid level on the bottle you labeled with 
test identification and Container 5. This container holds the remainder 
of the liquid water from the emission gases. If you collected 
condensable PM using Method 202 of appendix M to this part in 
conjunction with using this method, you must follow the procedures in 
Method 202 of appendix M to this part to recover impingers and silica 
used to collect moisture.
    (f) Container 6, Silica gel absorbent. Transfer the silica gel to 
its original container labeled with test identification and Container 6 
and seal. A funnel may make it easier to pour the silica gel without 
spilling. A rubber policeman may be used as an aid in removing the 
silica gel from the impinger. It is not necessary to remove the small 
amount of silica gel dust particles that may adhere to the impinger wall 
and are difficult to remove. Since the gain in weight is to be used for 
moisture calculations, do not use any water or other liquids to transfer 
the silica gel. If the silica gel has been weighed in the field to 
measure water content, it can be discarded. Otherwise, the contents of 
Container 6 are weighed during sample analysis.
    (g) Container 7, Acetone field reagent blank. Take approximately 
200 ml of the acetone directly from the wash bottle you used and place 
it in Container 7 labeled ``Acetone Field Reagent Blank.''
    8.7.6 Transport Procedures. Containers must remain in an upright 
position at all times during shipping. You do not have to ship the 
containers under dry or blue ice.

                           9.0 Quality Control

    9.1 Daily Quality Checks. You must perform daily quality checks of 
field log books and data entries and calculations using data quality 
indicators from this method and your site-specific test plan. You must 
review and evaluate recorded and transferred raw data, calculations, and 
documentation of testing procedures. You must initial or sign log book 
pages and data entry forms that were reviewed.
    9.2 Calculation Verification. Verify the calculations by 
independent, manual checks. You must flag any suspect data and identify 
the nature of the problem and potential effect on data quality. After 
you complete the test, prepare a data summary and compile all the 
calculations and raw data sheets.
    9.3 Conditions. You must document data and information on the 
process unit tested, the particulate control system used to control 
emissions, any non-particulate control system that may affect 
particulate emissions, the sampling train conditions, and weather 
conditions. Discontinue the test if the operating conditions may cause 
non-representative particulate emissions.
    9.4 Field Analytical Balance Calibration Check. Perform calibration 
check procedures on field analytical balances each day that they are 
used. You must use National Institute of Standards and Technology 
(NIST)-traceable weights at a mass approximately

[[Page 477]]

equal to the weight of the sample plus container you will weigh.
    10.0 Calibration and Standardization
    Maintain a log of all filterable particulate sampling and analysis 
calibrations. Include copies of the relevant portions of the calibration 
and field logs in the final test report.
    10.1 Gas Flow Velocities. You must use an S-type pitot tube that 
meets the required EPA specifications (EPA Publication 600/4-77-0217b) 
during these velocity measurements. (Note: If, as specified in Section 
8.7.2.3, testing is performed in stacks less than 26.5 inches in 
diameter, testers may use a standard pitot tube according to the 
requirements in Method 1 or 2 of appendix A-3 to part 60 of this 
chapter.) You must also complete the following:
    (a) Visually inspect the S-type pitot tube before sampling.
    (b) Leak check both legs of the pitot tube before and after 
sampling.
    (c) Maintain proper orientation of the S-type pitot tube while 
making measurements.
    10.1.1 S-type Pitot Tube Orientation. The S-type pitot tube is 
properly oriented when the yaw and the pitch axis are 90 degrees to the 
air flow.
    10.1.2 Average Velocity Pressure Record. Instead of recording either 
high or low values, record the average velocity pressure at each point 
during flow measurements.
    10.1.3 Pitot Tube Coefficient. Determine the pitot tube coefficient 
based on physical measurement techniques described in Method 2 of 
appendix A-1 to part 60. (Note: You must calibrate the pitot tube on the 
sampling head because of potential interferences from the cyclone body. 
Refer to Section 8.7.2 for additional information.)
    10.2 Thermocouple Calibration. You must calibrate the thermocouples 
using the procedures described in Section 10.3.1 of Method 2 of appendix 
A-1 to part 60 or Alternative Method 2 Thermocouple Calibration (ALT-
011). Calibrate each temperature sensor at a minimum of three points 
over the anticipated range of use against a NIST-traceable thermometer. 
Alternatively, a reference thermocouple and potentiometer calibrated 
against NIST standards can be used.
    10.3 Nozzles. You may use stainless steel (316 or equivalent), high-
temperature steel alloy, or fluoropolymer-coated nozzles for isokinetic 
sampling. Make sure that all nozzles are thoroughly cleaned, visually 
inspected, and calibrated according to the procedure outlined in Section 
10.1 of Method 5 of appendix A-3 to part 60.
    10.4 Dry Gas Meter Calibration. Calibrate your dry gas meter 
following the calibration procedures in Section 16.1 of Method 5 of 
appendix A-3 to part 60. Also, make sure you fully calibrate the dry gas 
meter to determine the volume correction factor prior to field use. 
Post-test calibration checks must be performed as soon as possible after 
the equipment has been returned to the shop. Your pre-test and post-test 
calibrations must agree within 5 percent.

                       11.0 Analytical Procedures

    11.1 Analytical Data Sheet. Record all data on the analytical data 
sheet. Obtain the data sheet from Figure 5-6 of Method 5 of appendix A-3 
to part 60. Alternatively, data may be recorded electronically using 
software applications such as the Electronic Reporting Tool located at 
http://www.epa.gov/ttn/chief/ert/ert_tool.html.
    11.2 Dry Weight of PM. Determine the dry weight of particulate 
following procedures outlined in this section.
    11.2.1 Container 1, Less than or Equal to PM2.5 
Micrometer Filterable Particulate. Transfer the filter and any loose 
particulate from the sample container to a tared weighing dish or pan 
that is inert to solvent or mineral acids. Desiccate for 24 hours in a 
dessicator containing anhydrous calcium sulfate. Weigh to a constant 
weight and report the results to the nearest 0.1 mg. (See Section 3.0 
for a definition of Constant weight.) If constant weight requirements 
cannot be met, the filter must be treated as described in Section 11.2.1 
of Method 202 of appendix M to this part. Note: The nozzle and front 
half wash and filter collected at or below 30 [deg]C (85 [deg]F) may not 
be heated and must be maintained at or below 30 [deg]C (85 [deg]F).
    11.2.2 Container 2, Greater than PM10 Micrometer 
Filterable Particulate Acetone Rinse. Separately treat this container 
like Container 4.
    11.2.3 Container 3, Filterable Particulate Less than or Equal to 10 
Micrometer and Greater than 2.5 Micrometers Acetone Rinse. Separately 
treat this container like Container 4.
    11.2.4 Container 4, Less than or Equal to PM2.5 
Micrometers Acetone Rinse of the Exit Tube of Cyclone IV and Front Half 
of the Filter Holder. Note the level of liquid in the container and 
confirm on the analysis sheet whether leakage occurred during transport. 
If a noticeable amount of leakage has occurred, either void the sample 
or use methods (subject to the approval of the Administrator) to correct 
the final results. Quantitatively transfer the contents to a tared 250 
ml beaker or tared fluoropolymer beaker liner, and evaporate to dryness 
at room temperature and pressure in a laboratory hood. Desiccate for 24 
hours and weigh to a constant weight. Report the results to the nearest 
0.1 mg.
    11.2.5 Container 5, Cold Impinger Water. If the amount of water has 
not been determined in the field, note the level of liquid in the 
container and confirm on the analysis sheet whether leakage occurred 
during transport. If a noticeable amount of leakage has occurred, either 
void the sample or use

[[Page 478]]

methods (subject to the approval of the Administrator) to correct the 
final results. Measure the liquid in this container either 
volumetrically to 1 ml or gravimetrically to 
0.5 g.
    11.2.6 Container 6, Silica Gel Absorbent. Weigh the spent silica 
gel (or silica gel plus impinger) to the nearest 0.5 g using a balance. 
This step may be conducted in the field.
    11.2.7 Container 7, Acetone Field Reagent Blank. Use 150 ml of 
acetone from the blank container used for this analysis. Transfer 150 ml 
of the acetone to a clean 250-ml beaker or tared fluoropolymer beaker 
liner. Evaporate the acetone to dryness at room temperature and pressure 
in a laboratory hood. Following evaporation, desiccate the residue for 
24 hours in a desiccator containing anhydrous calcium sulfate. Weigh and 
report the results to the nearest 0.1 mg.

                   12.0 Calculations and Data Analysis

    12.1 Nomenclature. Report results in International System of Units 
(SI units) unless the regulatory authority that established the 
requirement to use this test method specifies reporting in English 
units. The following nomenclature is used.

A = Area of stack or duct at sampling location, square inches.
An = Area of nozzle, square feet.
bf = Average blockage factor calculated in Equation 26, 
          dimensionless.
Bws = Moisture content of gas stream, fraction (e.g., 10 
          percent H2O is Bws = 0.10).
C = Cunningham correction factor for particle diameter, Dp, 
          and calculated using the actual stack gas temperature, 
          dimensionless.
%CO2 = Carbon Dioxide content of gas stream, percent by 
          volume.
Ca = Acetone blank concentration, mg/mg.
CfPM10 = Conc. of filterable PM10, gr/
          DSCF.
CfPM2.5 = Conc. of filterable PM2.5, 
          gr/DSCF.
Cp = Pitot coefficient for the combined cyclone pitot, 
          dimensionless.
Cp' = Coefficient for the pitot used in the preliminary 
          traverse, dimensionless.
Cr = Re-estimated Cunningham correction factor for particle 
          diameter equivalent to the actual cut size diameter and 
          calculated using the actual stack gas temperature, 
          dimensionless.
Ctf = Conc. of total filterable PM, gr/DSCF.
C1 = -150.3162 (micropoise)
C2 = 18.0614 (micropoise/K\0.5\) = 13.4622 (micropoise/
          R\0.5\)
C3 = 1.19183 x 10\6\ (micropoise/K\2\) = 3.86153 x 10\6\ 
          (micropoise/R\2\)
C4 = 0.591123 (micropoise)
C5 = 91.9723 (micropoise)
C6 = 4.91705 x 10-5 (micropoise/K\2\) = 1.51761 x 
          10-5 (micropoise/R\2\)
D = Inner diameter of sampling nozzle mounted on Cyclone I, inches.
Dp = Physical particle size, micrometers.
D50 = Particle cut diameter, micrometers.
D50-1 = Re-calculated particle cut diameters based on re-
          estimated Cr, micrometers.
D50LL = Cut diameter for cyclone I corresponding to the 2.25 
          micrometer cut diameter for cyclone IV, micrometers.
D50N = D50 value for cyclone IV calculated during 
          the Nth iterative step, micrometers.
D50(N + 1) = D50 value for cyclone IV calculated 
          during the N + 1 iterative step, micrometers.
D50T = Cyclone I cut diameter corresponding to the middle of 
          the overlap zone shown in Figure 10 of Section 17, 
          micrometers.
I = Percent isokinetic sampling, dimensionless.
Kp = 85.49, ((ft/sec)/(pounds/mole -[deg]R)).
ma = Mass of residue of acetone after evaporation, mg.
Md = Molecular weight of dry gas, pounds/pound mole.
mg = Milligram.
mg/L = Milligram per liter.
Mw = Molecular weight of wet gas, pounds/pound mole.
M1 = Milligrams of PM collected on the filter, less than or 
          equal to 2.5 micrometers.
M2 = Milligrams of PM recovered from Container 2 (acetone 
          blank corrected), greater than 10 micrometers.
M3 = Milligrams of PM recovered from Container 3 (acetone 
          blank corrected), less than or equal to 10 and greater than 
          2.5 micrometers.
M4 = Milligrams of PM recovered from Container 4 (acetone 
          blank corrected), less than or equal to 2.5 micrometers.
Ntp = Number of iterative steps or total traverse points.
Nre = Reynolds number, dimensionless.
%O2,wet = Oxygen content of gas stream, % by volume of wet 
          gas.

(Note: The oxygen percentage used in Equation 3 is on a wet gas basis. 
          That means that since oxygen is typically measured on a dry 
          gas basis, the measured percent O2 must be 
          multiplied by the quantity (1-Bws) to convert to 
          the actual volume fraction. Therefore, %O2,wet = 
          (1-Bws) * %O2, dry)

Pbar = Barometric pressure, inches Hg.
Ps = Absolute stack gas pressure, inches Hg.
Qs = Sampling rate for cyclone I to achieve specified 
          D50.
QsST = Dry gas sampling rate through the sampling assembly, 
          DSCFM.
QI = Sampling rate for cyclone I to achieve specified 
          D50.
Rmax = Nozzle/stack velocity ratio parameter, dimensionless.
Rmin = Nozzle/stack velocity ratio parameter, dimensionless.
Tm = Meter box and orifice gas temperature, [deg]R.

[[Page 479]]

tn = Sampling time at point n, min.
tr = Total projected run time, min.
Ts = Absolute stack gas temperature, [deg]R.
t1 = Sampling time at point 1, min.
vmax = Maximum gas velocity calculated from Equations 18 or 
          19, ft/sec.
vmin = Minimum gas velocity calculated from Equations 16 or 
          17, ft/sec.
vn = Sample gas velocity in the nozzle, ft/sec.
vs = Velocity of stack gas, ft/sec.
Va = Volume of acetone blank, ml.
Vaw = Volume of acetone used in sample recovery wash, ml.
Vc = Quantity of water captured in impingers and silica gel, 
          ml.
Vm = Dry gas meter volume sampled, ACF.
Vms = Dry gas meter volume sampled, corrected to standard 
          conditions, DSCF.
Vws = Volume of water vapor, SCF.
Vic = Volume of impinger contents sample, ml.
Wa = Weight of blank residue in acetone used to recover 
          samples, mg.
W2,3,4 = Weight of PM recovered from Containers 2, 3, and 
          4, mg.
Z = Ratio between estimated cyclone IV D50 values, 
          dimensionless.
[Delta]H = Meter box orifice pressure drop, inches W.C.
[Delta]H@ = Pressure drop across orifice at flow rate of 0.75 
          SCFM at standard conditions, inches W.C.

(Note: Specific to each orifice and meter box.)

[([Delta]p)\0.5\]avg = Average of square roots of the 
          velocity pressures measured during the preliminary traverse, 
          inches W.C.
[Delta]pm = Observed velocity pressure using S-type pitot 
          tube in preliminary traverse, inches W.C.
[Delta]pavg = Average velocity pressure, inches W.C.
[Delta]pmax = Maximum velocity pressure, inches W.C.
[Delta]pmin = Minimum velocity pressure, inches W.C.
[Delta]pn = Velocity pressure measured at point n during the 
          test run, inches W.C.
[Delta]ps = Velocity pressure calculated in Equation 25, 
          inches W.C.
[Delta]ps1 = Velocity pressure adjusted for combined cyclone 
          pitot tube, inches W.C.
[Delta]ps2 = Velocity pressure corrected for blockage, inches 
          W.C.
[Delta]p1 = Velocity pressure measured at point 1, inches 
          W.C.
[gamma] = Dry gas meter gamma value, dimensionless.
[micro] = Gas viscosity, micropoise.
[theta] = Total run time, min.
[rho]a = Density of acetone, mg/ml (see label on bottle).
12.0 = Constant calculated as 60 percent of 20.5 square inch cross-
          sectional area of combined cyclone head, square inches.

    12.2 Calculations. Perform all of the calculations found in Table 6 
of Section 17. Table 6 of Section 17 also provides instructions and 
references for the calculations.
    12.3 Analyses. Analyze D50 of cyclone IV and the 
concentrations of the PM in the various size ranges.
    12.3.1 D50 of Cyclone IV. To determine the actual 
D50 for cyclone IV, recalculate the Cunningham correction 
factor and the Reynolds number for the best estimate of cyclone IV 
D50. The following sections describe additional information 
on how to recalculate the Cunningham correction factor and determine 
which Reynolds number to use.
    12.3.1.1 Cunningham correction factor. Recalculate the initial 
estimate of the Cunningham correction factor using the actual test data. 
Insert the actual test run data and D50 of 2.5 micrometers 
into Equation 4. This will give you a new Cunningham correction factor 
based on actual data.
    12.3.1.2 Initial D50 for cyclone IV. Determine the initial estimate 
for cyclone IV D50 using the test condition Reynolds number 
calculated with Equation 10 as indicated in Table 3 of Section 17. Refer 
to the following instructions.
    (a) If the Reynolds number is less than 3,162, calculate the 
D50 for cyclone IV with Equation 34, using actual test data.
    (b) If the Reynolds number is greater than or equal to 3,162, 
calculate the D50 for cyclone IV with Equation 35 using 
actual test data.
    (c) Insert the ``new'' D50 value calculated by either 
Equation 34 or 35 into Equation 36 to re-establish the Cunningham 
Correction Factor (Cr). (Note: Use the test condition 
calculated Reynolds number to determine the most appropriate equation 
(Equation 34 or 35).)
    12.3.1.3 Re-establish cyclone IV D50. Use the re-established 
Cunningham correction factor (calculated in the previous step) and the 
calculated Reynolds number to determine D50-1.
    (a) Use Equation 37 to calculate the re-established cyclone IV 
D50-1 if the Reynolds number is less than 3,162.
    (b) Use Equation 38 to calculate the re-established cyclone IV 
D50-1 if the Reynolds number is greater than or equal to 
3,162.
    12.3.1.4 Establish ``Z'' values. The ``Z'' value is the result of an 
analysis that you must perform to determine if the Cr is 
acceptable. Compare the calculated cyclone IV D50 (either 
Equation 34 or 35) to the re-established cyclone IV D50-1 
(either Equation 36 or 37) values based upon the test condition 
calculated Reynolds number (Equation 39). Follow these procedures.
    (a) Use Equation 39 to calculate the ``Z'' values. If the ``Z'' 
value is between 0.99 and 1.01, the D50-1 value is the best 
estimate of the cyclone IV D50 cut diameter for your test 
run.

[[Page 480]]

    (b) If the ``Z'' value is greater than 1.01 or less than 0.99, re-
establish a Cr based on the D50-1 value determined 
in either Equations 36 or 37, depending upon the test condition Reynolds 
number.
    (c) Use the second revised Cr to re-calculate the cyclone 
IV D50.
    (d) Repeat this iterative process as many times as necessary using 
the prescribed equations until you achieve the criteria documented in 
Equation 40.
    12.3.2 Particulate Concentration. Use the particulate catch weights 
in the combined cyclone sampling train to calculate the concentration of 
PM in the various size ranges. You must correct the concentrations for 
the acetone blank.
    12.3.2.1 Acetone blank concentration. Use Equation 42 to calculate 
the acetone blank concentration (Ca).
    12.3.2.2 Acetone blank residue weight. Use Equation 44 to calculate 
the acetone blank weight (Wa (2,3,4)). Subtract the weight of 
the acetone blank from the particulate weight catch in each size 
fraction.
    12.3.2.3 Particulate weight catch per size fraction. Correct each of 
the PM weights per size fraction by subtracting the acetone blank weight 
(i.e., M2,3,4-Wa). (Note: Do not subtract a blank 
value of greater than 0.1 mg per 100 ml of the acetone used from the 
sample recovery.) Use the following procedures.
    (a) Use Equation 45 to calculate the PM recovered from Containers 
1, 2, 3, and 4. This is the total collectible PM (Ctf).
    (b) Use Equation 46 to determine the quantitative recovery of 
PM10 (CfPM10) from Containers 1, 3, 
and 4.
    (c) Use Equation 47 to determine the quantitative recovery of 
PM2.5 (CfPM2.5) recovered from 
Containers 1 and 4.
    12.4 Reporting. You must prepare a test report following the 
guidance in EPA Guidance Document 043, Preparation and Review of Test 
Reports (December 1998).
    12.5 Equations. Use the following equations to complete the 
calculations required in this test method.
    Molecular Weight of Dry Gas. Calculate the molecular weight of the 
dry gas using Equation 1.
[GRAPHIC] [TIFF OMITTED] TR21DE10.000

    Molecular Weight of Wet Gas. Calculate the molecular weight of the 
stack gas on a wet basis using Equation 2.
[GRAPHIC] [TIFF OMITTED] TR21DE10.001

    Gas Stream Viscosity. Calculate the gas stream viscosity using 
Equation 3. This equation uses constants for gas temperatures in [deg]R.
[GRAPHIC] [TIFF OMITTED] TR21DE10.002

    Cunningham Correction Factor. The Cunningham correction factor is 
calculated for a 2.25 micrometer diameter particle.
[GRAPHIC] [TIFF OMITTED] TR21DE10.003

    Lower Limit Cut Diameter for Cyclone I for Nre Less than 3,162. The 
Cunningham correction factor is calculated for a 2.25 micrometer 
diameter particle.

[[Page 481]]

[GRAPHIC] [TIFF OMITTED] TR21DE10.004

    Cut Diameter for Cyclone I for the Middle of the Overlap Zone.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.005
    
    Sampling Rate Using Both PM10 and PM2.5 Cyclones.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.006
    
    Sampling Rate Using Only PM2.5 Cyclone.
    [GRAPHIC] [TIFF OMITTED] TR30AU16.001
    
    Reynolds Number.
    [GRAPHIC] [TIFF OMITTED] TR21MR18.001
    
    Meter Box Orifice Pressure Drop.

[[Page 482]]

[GRAPHIC] [TIFF OMITTED] TR21DE10.010

    Lower Limit Cut Diameter for Cyclone I for Nre Greater than or Equal 
to 3,162. The Cunningham correction factor is calculated for a 2.25 
micrometer diameter particle.
[GRAPHIC] [TIFF OMITTED] TR21DE10.011

    Velocity of Stack Gas. Correct the mean preliminary velocity 
pressure for Cp and blockage using Equations 25, 26, and 27.
[GRAPHIC] [TIFF OMITTED] TR21DE10.012

    Calculated Nozzle Diameter for Acceptable Sampling Rate.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.013
    
    Velocity of Gas in Nozzle.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.014
    
    Minimum Nozzle/Stack Velocity Ratio Parameter.

[[Page 483]]

[GRAPHIC] [TIFF OMITTED] TR21DE10.015

    Maximum Nozzle/Stack Velocity Ratio Parameter.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.016
    
    Minimum Gas Velocity for Rmin Less than 0.5.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.017
    
    Minimum Gas Velocity for Rmin Greater than or Equal to 0.5.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.018
    
    Maximum Gas Velocity for Rmax Less than to 1.5.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.019
    
    Maximum Gas Velocity for Rmax Greater than or Equal to 1.5.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.020
    
    Minimum Velocity Pressure.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.021
    
    Maximum Velocity Pressure.
      

[[Page 484]]

[GRAPHIC] [TIFF OMITTED] TR21DE10.022

    Sampling Dwell Time at Each Point. Ntp is the total 
number of traverse points. You must use the preliminary velocity 
traverse data.
[GRAPHIC] [TIFF OMITTED] TR14NO18.059

    Adjusted Velocity Pressure.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.024
    
    Average Probe Blockage Factor.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.025
    
    Velocity Pressure.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.026
    
    Dry Gas Volume Sampled at Standard Conditions.

[[Page 485]]

[GRAPHIC] [TIFF OMITTED] TR21DE10.027

    Sample Flow Rate at Standard Conditions.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.028
    
    Volume of Water Vapor.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.029
    
    Moisture Content of Gas Stream.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.030
    
    Sampling Rate.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.031
    
    (Note: The viscosity and Reynolds Number must be recalculated using 
the actual stack temperature, moisture, and oxygen content.)
    Actual Particle Cut Diameter for Cyclone I. This is based on actual 
temperatures and pressures measured during the test run.
[GRAPHIC] [TIFF OMITTED] TR21DE10.032

    Particle Cut Diameter for Nre Less than 3,162 for Cyclone IV. C must 
be recalculated using the actual test data and a D50 for 2.5 
micrometer diameter particle size.

[[Page 486]]

[GRAPHIC] [TIFF OMITTED] TR21DE10.033

    Particle Cut Diameter for Nre Greater than or Equal to 3,162 for 
Cyclone IV. C must be recalculated using the actual test run data and a 
D50 for 2.5 micrometer diameter particle size.
[GRAPHIC] [TIFF OMITTED] TR21DE10.034

    Re-estimated Cunningham Correction Factor. You must use the actual 
test run Reynolds Number (Nre) value and select the 
appropriate D50 from Equation 33 or 34 (or Equation 37 or 38 
if reiterating).
[GRAPHIC] [TIFF OMITTED] TR21DE10.035

    Re-calculated Particle Cut Diameter for Nre Less than 3,162.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.036
    
    Re-calculated Particle Cut Diameter for N Greater than or Equal to 
3,162.
[GRAPHIC] [TIFF OMITTED] TR21DE10.037

    Ratio (Z) Between D50 and D50	1 Values.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.038
    
    Acceptance Criteria for Z Values. The number of iterative steps is 
represented by N.

[[Page 487]]

[GRAPHIC] [TIFF OMITTED] TR21DE10.039

    Percent Isokinetic Sampling.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.040
    
    Acetone Blank Concentration.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.041
    
    Acetone Blank Correction Weight.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.042
    
    Acetone Blank Weight.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.043
    
    Concentration of Total Filterable PM.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.044
    
    Concentration of Filterable PM10.
    [GRAPHIC] [TIFF OMITTED] TR21DE10.045
    
    Concentration of Filterable PM2.5.

[[Page 488]]

[GRAPHIC] [TIFF OMITTED] TR21DE10.046

                         13.0 Method Performance

    13.1 Field evaluation of PM10 and total PM showed that 
the precision of constant sampling rate method was the same magnitude as 
Method 17 of appendix A-6 to part 60 (approximately five percent). 
Precision in PM10 and total PM between multiple trains showed 
standard deviations of four to five percent and total mass compared to 
4.7 percent observed for Method 17 in simultaneous test runs at a 
Portland cement clinker cooler exhaust. The accuracy of the constant 
sampling rate PM10 method for total mass, referenced to 
Method 17, was -2 4.4 percent (Farthing, 1988a).
    13.2 Laboratory evaluation and guidance for PM10 cyclones 
were designed to limit error due to spatial variations to 10 percent. 
The maximum allowable error due to an isokinetic sampling was limited to 
20 percent for 10 micrometer particles in 
laboratory tests (Farthing, 1988b).
    13.3 A field evaluation of the revised Method 201A by EPA showed 
that the detection limit was 2.54 mg for total filterable PM, 1.44 mg 
for filterable PM10, and 1.35 mg for PM2.5. The 
precision resulting from 10 quadruplicate tests (40 test runs) conducted 
for the field evaluation was 6.7 percent relative standard deviation. 
The field evaluation also showed that the blank expected from Method 
201A was less than 0.9 mg (EPA, 2010).

                       14.0 Alternative Procedures

    Alternative methods for estimating the moisture content (ALT-008) 
and thermocouple calibration (ALT-011) can be found at http://
www.epa.gov/ttn/emc/approalt.html.

                          15.0 Waste Management

    [Reserved]

                             16.0 References

    (1) Dawes, S.S., and W.E. Farthing. 1990. ``Application Guide for 
Measurement of PM2.5 at Stationary Sources,'' U.S. 
Environmental Protection Agency, Atmospheric Research and Exposure 
Assessment Laboratory, Research Triangle Park, NC, 27511, EPA-600/3-90/
057 (NTIS No.: PB 90-247198).
    (2) Farthing, et al. 1988a. ``PM10 Source Measurement 
Methodology: Field Studies,'' EPA 600/3-88/055, NTIS PB89-194278/AS, 
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711.
    (3) Farthing, W.E., and S.S. Dawes. 1988b. ``Application Guide for 
Source PM10 Measurement with Constant Sampling Rate,'' EPA/
600/3-88-057, U.S. Environmental Protection Agency, Research Triangle 
Park, NC 27711.
    (4) Richards, J.R. 1996. ``Test protocol: PCA PM10/
PM2.5 Emission Factor Chemical Characterization Testing,'' 
PCA R&D Serial No. 2081, Portland Cement Association.
    (5) U.S. Environmental Protection Agency, Federal Reference Methods 
1 through 5 and Method 17, 40 CFR part 60, Appendix A-1 through A-3 and 
A-6.
    (6) U.S. Environmental Protection Agency. 2010. ``Field Evaluation 
of an Improved Method for Sampling and Analysis of Filterable and 
Condensable Particulate Matter.'' Office of Air Quality Planning and 
Standards, Sector Policy and Program Division Monitoring Policy Group. 
Research Triangle Park, NC 27711.

         17.0 Tables, Diagrams, Flowcharts, and Validation Data

    You must use the following tables, diagrams, flowcharts, and data to 
complete this test method successfully.

                                       Table 1--Typical PM Concentrations
----------------------------------------------------------------------------------------------------------------
               Particle size range                                 Concentration and % by weight
----------------------------------------------------------------------------------------------------------------
Total collectible particulate...................  0.015 gr/DSCF.
Less than or equal to 10 and greater than 2.5     40% of total collectible PM.
 micrometers.
<=2.5 micrometers...............................  20% of total collectible PM.
----------------------------------------------------------------------------------------------------------------


              Table 2--Required Cyclone Cut Diameters (D50)
------------------------------------------------------------------------
                                            Min. cut         Max. cut
                Cyclone                     diameter         diameter
                                          (micrometer)     (micrometer)
------------------------------------------------------------------------
PM10 Cyclone (Cyclone I from five                     9               11
 stage cyclone).......................
PM2.5 Cyclone (Cyclone IV from five                2.25             2.75
 stage cyclone).......................
------------------------------------------------------------------------


[[Page 489]]


                       Table 3--Test Calculations
------------------------------------------------------------------------
   If you are using . . .      To calculate . . .      Then use . . .
------------------------------------------------------------------------
Preliminary data............  Dry gas molecular     Equation 1.
                               weight, Md.
Dry gas molecular weight      wet gas molecular     Equation 2.\a\
 (Md) and preliminary          weight, MW.
 moisture content of the gas
 stream.
Stack gas temperature, and    gas viscosity,        Equation 3.
 oxygen and moisture content   [micro].
 of the gas stream.
Gas viscosity, [micro]......  Cunningham            Equation 4.
                               correction factor
                               \b\, C.
Reynolds Number \c\ (Nre)...  Preliminary lower     Equation 5.
Nre less than 3,162.........   limit cut diameter
                               for cyclone I,
                               D50LL.
D50LL from Equation 5.......  Cut diameter for      Equation 6.
                               cyclone I for
                               middle of the
                               overlap zone, D50T.
D50T from Equation 6........  Final sampling rate   Equation 7.
                               for cyclone I,
                               QI(Qs).
D50 for PM2.5 cyclone and     Final sampling rate   Equation 8.
 Nre less than 3,162.          for cyclone IV, QIV.
D50 for PM2.5 cyclone and     Final sampling rate   Equation 9.
 Nre greater than or equal     for cyclone IV, QIV.
 to 3,162.
QI(Qs) from Equation 7......  Verify the assumed    Equation 10.
                               Reynolds number,
                               Nre.
------------------------------------------------------------------------
\a\ Use Method 4 to determine the moisture content of the stack gas. Use
  a wet bulb-dry bulb measurement device or hand-held hygrometer to
  estimate moisture content of sources with gas temperature less than
  160 [deg]F.
\b\ For the lower cut diameter of cyclone IV, 2.25 micrometer.
\c\ Verify the assumed Reynolds number, using the procedure in Section
  8.5.1, before proceeding to Equation 11.


                           Table 4--[Delta]H Values Based on Preliminary Traverse Data
----------------------------------------------------------------------------------------------------------------
 Stack Temperature ([deg]R)          Ts--50[deg]                      Ts                     Ts + 50[deg]
----------------------------------------------------------------------------------------------------------------
 [Delta]H, (inches W.C.)                         a                            a                           a
----------------------------------------------------------------------------------------------------------------
\a\ These values are to be filled in by the stack tester.


          Table 5--Verification of the Assumed Reynolds Number
------------------------------------------------------------------------
       If the Nre is . . .            Then . . .           And . . .
------------------------------------------------------------------------
Less than 3,162.................  Calculate [Delta]H  Assume original
                                   for the meter box.  D50LL is correct
Greater than or equal to 3,162..  Recalculate D50LL   Substitute the
                                   using Equation 12.  ``new'' D50LL
                                                       into Equation 6
                                                       to recalculate
                                                       D50T.
------------------------------------------------------------------------


          Table 6--Calculations for Recovery of PM10 and PM2.5
------------------------------------------------------------------------
              Calculations                 Instructions and References
------------------------------------------------------------------------
Average dry gas meter temperature......  See field test data sheet.
Average orifice pressure drop..........  See field test data sheet.
Dry gas volume (Vms)...................  Use Equation 28 to correct the
                                          sample volume measured by the
                                          dry gas meter to standard
                                          conditions (20 [deg]C, 760 mm
                                          Hg or 68 [deg]F, 29.92 inches
                                          Hg).
Dry gas sampling rate (QsST)...........  Must be calculated using
                                          Equation 29.
Volume of water condensed (Vws)........  Use Equation 30 to determine
                                          the water condensed in the
                                          impingers and silica gel
                                          combination. Determine the
                                          total moisture catch by
                                          measuring the change in volume
                                          or weight in the impingers and
                                          weighing the silica gel.
Moisture content of gas stream (Bws)...  Calculate this using Equation
                                          31.
Sampling rate (Qs).....................  Calculate this using Equation
                                          32.
Test condition Reynolds number\a\......  Use Equation 10 to calculate
                                          the actual Reynolds number
                                          during test conditions.
Actual D50 of cyclone I................  Calculate this using Equation
                                          33. This calculation is based
                                          on the average temperatures
                                          and pressures measured during
                                          the test run.
Stack gas velocity (vs)................  Calculate this using Equation
                                          13.
Percent isokinetic rate (%I)...........  Calculate this using Equation
                                          41.
------------------------------------------------------------------------
\a\ Calculate the Reynolds number at the cyclone IV inlet during the
  test based on: (1) The sampling rate for the combined cyclone head,
  (2) the actual gas viscosity for the test, and (3) the dry and wet gas
  stream molecular weights.


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Method 202--Dry Impinger Method for Determining Condensable Particulate 
                    Emissions From Stationary Sources

                       1.0 Scope and Applicability

    1.1 Scope. The U.S. Environmental Protection Agency (U.S. EPA or 
``we'') developed this method to describe the procedures that the stack 
tester (``you'') must follow to measure condensable particulate matter 
(CPM) emissions from stationary sources. This method includes procedures 
for measuring both organic and inorganic CPM.
    1.2 Applicability. This method addresses the equipment, preparation, 
and analysis necessary to measure only CPM. You can use this method only 
for stationary source emission measurements. You can use this method to 
measure CPM from stationary source emissions after filterable 
particulate matter (PM) has been removed. CPM is measured in the 
emissions after removal from the stack and after passing through a 
filter.
    (a) If the gas filtration temperature exceeds 30 [deg]C (85 [deg]F) 
and you must measure both the filterable and condensable (material that 
condenses after passing through a filter) components of total primary 
(direct) PM emissions to the atmosphere, then you must combine the 
procedures in this method with the procedures in Method 201A of appendix 
M to this part for measuring filterable PM. However, if the gas 
filtration temperature never exceeds 30 [deg]C (85 [deg]F), then use of 
this method is not required to measure total primary PM.
    (b) If Method 17 of appendix A-6 to part 60 is used in conjunction 
with this method and constant weight requirements for the in-stack 
filter cannot be met, the Method 17 filter and sampling nozzle rinse 
must be treated as described in Sections 8.5.4.4 and 11.2.1 of this 
method. (See Section 3.0 for a definition of constant weight.) Extracts 
resulting from the use of this procedure must be filtered to remove 
filter fragments before the filter is processed and weighed.
    1.3 Responsibility. You are responsible for obtaining the equipment 
and supplies you will need to use this method. You should also develop 
your own procedures for following this method and any additional 
procedures to ensure accurate sampling and analytical measurements.

[[Page 500]]

    1.4 Additional Methods. To obtain reliable results, you should have 
a thorough knowledge of the following test methods that are found in 
appendices A-1 through A-3 and A-6 to part 60, and in appendix M to this 
part:
    (a) Method 1--Sample and velocity traverses for stationary sources.
    (b) Method 2--Determination of stack gas velocity and volumetric 
flow rate (Type S pitot tube).
    (c) Method 3--Gas analysis for the determination of dry molecular 
weight.
    (d) Method 4--Determination of moisture content in stack gases.
    (e) Method 5--Determination of particulate matter emissions from 
stationary sources.
    (f) Method 17--Determination of particulate matter emissions from 
stationary sources (in-stack filtration method).
    (g) Method 201A--Determination of PM10 and 
PM2.5 emissions from stationary sources (Constant sampling 
rate procedure).
    (h) You will need additional test methods to measure filterable PM. 
You may use Method 5 (including Method 5A, 5D and 5I but not 5B, 5E, 5F, 
5G, or 5H) of appendix A-3 to part 60, or Method 17 of appendix A-6 to 
part 60, or Method 201A of appendix M to this part to collect filterable 
PM from stationary sources with temperatures above 30 [deg]C (85 [deg]F) 
in conjunction with this method. However, if the gas filtration 
temperature never exceeds 30 [deg]C (85 [deg]F), then use of this method 
is not required to measure total primary PM.
    1.5 Limitations. You can use this method to measure emissions in 
stacks that have entrained droplets only when this method is combined 
with a filterable PM test method that operates at high enough 
temperatures to cause water droplets sampled through the probe to become 
vaporous.
    1.6 Conditions. You must maintain isokinetic sampling conditions to 
meet the requirements of the filterable PM test method used in 
conjunction with this method. You must sample at the required number of 
sampling points specified in Method 5 of appendix A-3 to part 60, Method 
17 of appendix A-6 to part 60, or Method 201A of appendix M to this 
part. Also, if you are using this method as an alternative to a required 
performance test method, you must receive approval from the regulatory 
authority that established the requirement to use this test method prior 
to conducting the test.

                          2.0 Summary of Method

    2.1 Summary. The CPM is collected in dry impingers after filterable 
PM has been collected on a filter maintained as specified in either 
Method 5 of appendix A-3 to part 60, Method 17 of appendix A-6 to part 
60, or Method 201A of appendix M to this part. The organic and aqueous 
fractions of the impingers and an out-of-stack CPM filter are then taken 
to dryness and weighed. The total of the impinger fractions and the CPM 
filter represents the CPM. Compared to the version of Method 202 that 
was promulgated on December 17, 1991, this method eliminates the use of 
water as the collection media in impingers and includes the addition of 
a condenser followed by a water dropout impinger immediately after the 
final in-stack or heated filter. This method also includes the addition 
of one modified Greenburg Smith impinger (backup impinger) and a CPM 
filter following the water dropout impinger. Figure 1 of Section 18 
presents the schematic of the sampling train configured with these 
changes.
    2.1.1 Condensable PM. CPM is collected in the water dropout 
impinger, the modified Greenburg Smith impinger, and the CPM filter of 
the sampling train as described in this method. The impinger contents 
are purged with nitrogen immediately after sample collection to remove 
dissolved sulfur dioxide (SO2) gases from the impinger. The 
CPM filter is extracted with water and hexane. The impinger solution is 
then extracted with hexane. The organic and aqueous fractions are dried 
and the residues are weighed. The total of the aqueous and organic 
fractions represents the CPM.
    2.1.2 Dry Impinger and Additional Filter. The potential artifacts 
from SO2 are reduced using a condenser and water dropout 
impinger to separate CPM from reactive gases. No water is added to the 
impingers prior to the start of sampling. To improve the collection 
efficiency of CPM, an additional filter (the ``CPM filter'') is placed 
between the second and third impingers.

                             3.0 Definitions

    3.1 Condensable PM (CPM) means material that is vapor phase at stack 
conditions, but condenses and/or reacts upon cooling and dilution in the 
ambient air to form solid or liquid PM immediately after discharge from 
the stack. Note that all condensable PM is assumed to be in the 
PM2.5 size fraction.
    3.2 Constant weight means a difference of no more than 0.5 mg or one 
percent of total weight less tare weight, whichever is greater, between 
two consecutive weighings, with no less than six hours of desiccation 
time between weighings.
    3.3 Field Train Proof Blank. A field train proof blank is recovered 
on site from a clean, fully-assembled sampling train prior to conducting 
the first emissions test.
    3.4 Filterable PM means particles that are emitted directly by a 
source as a solid or liquid at stack or release conditions and captured 
on the filter of a stack test train.
    3.5 Primary PM (also known as direct PM) means particles that enter 
the atmosphere as a direct emission from a stack or an open source. 
Primary PM comprises two components: filterable PM and condensable PM. 
These two PM components have no upper particle size limit.

[[Page 501]]

    3.6 Primary PM2.5 (also known as direct PM2.5, total 
PM2.5, PM2.5, or combined filterable 
PM2.5 and condensable PM) means PM with an aerodynamic 
diameter less than or equal to 2.5 micrometers. These solid particles 
are emitted directly from an air emissions source or activity, or are 
the gaseous emissions or liquid droplets from an air emissions source or 
activity that condense to form PM at ambient temperatures. Direct 
PM2.5 emissions include elemental carbon, directly emitted 
organic carbon, directly emitted sulfate, directly emitted nitrate, and 
other inorganic particles (including but not limited to crustal 
material, metals, and sea salt).
    3.7 Primary PM10 (also known as direct PM10, total 
PM10, PM10, or the combination of filterable 
PM10 and condensable PM) means PM with an aerodynamic 
diameter equal to or less than 10 micrometers.
    3.8 ASTM E617-13. ASTM E617-13 ``Standard Specification for 
Laboratory Weights and Precisions Mass Standards,'' approved May 1, 
2013, was developed and adopted by the American Society for Testing and 
Materials (ASTM). The standards cover weights and mass standards used in 
laboratories for specific classes. The ASTM E617-13 standard has been 
approved for incorporation by reference by the Director of the Office of 
the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 
51. The standard may be obtained from http://www.astm.org or from the 
ASTM at 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 
19428-2959. All approved material is available for inspection at EPA WJC 
West Building, Room 3334, 1301 Constitution Ave. NW., Washington, DC 
20460, telephone number 202-566-1744. It is also available for 
inspection at the National Archives and Records Administration (NARA). 
For information on the availability of this material at NARA, call 202-
741-6030 or go to http://www.archives.gov/federal_register/code_of 
_federal_ regulations/ibr_locations.html.

                            4.0 Interferences

    [Reserved]

                               5.0 Safety

    Disclaimer. Because the performance of this method may require the 
use of hazardous materials, operations, and equipment, you should 
develop a health and safety plan to ensure the safety of your employees 
who are on site conducting the particulate emission test. Your plan 
should conform with all applicable Occupational Safety and Health 
Administration, Mine Safety and Health Administration, and Department of 
Transportation regulatory requirements. Because of the unique situations 
at some facilities and because some facilities may have more stringent 
requirements than is required by State or federal laws, you may have to 
develop procedures to conform to the plant health and safety 
requirements.

                       6.0 Equipment and Supplies

    The equipment used in the filterable particulate portion of the 
sampling train is described in Methods 5 and 17 of appendix A-1 through 
A-3 and A-6 to part 60 and Method 201A of appendix M to this part. The 
equipment used in the CPM portion of the train is described in this 
section.
    6.1 Condensable Particulate Sampling Train Components. The sampling 
train for this method is used in addition to filterable particulate 
collection using Method 5 of appendix A-3 to part 60, Method 17 of 
appendix A-6 to part 60, or Method 201A of appendix M to this part. This 
method includes the following exceptions or additions:
    6.1.1 Probe Extension and Liner. The probe extension between the 
filterable particulate filter and the condenser must be glass- or 
fluoropolymer-lined. Follow the specifications for the probe liner 
specified in Section 6.1.1.2 of Method 5 of appendix A-3 to part 60.
    6.1.2 Condenser and Impingers. You must add the following components 
to the filterable particulate sampling train: A Method 23 type condenser 
as described in Section 2.1.2 of Method 23 of appendix A-8 to part 60, 
followed by a water dropout impinger or flask, followed by a modified 
Greenburg-Smith impinger (backup impinger) with an open tube tip as 
described in Section 6.1.1.8 of Method 5 of appendix A-3 to part 60.
    6.1.3 CPM Filter Holder. The modified Greenburg-Smith impinger is 
followed by a filter holder that is either glass, stainless steel (316 
or equivalent), or fluoropolymer-coated stainless steel. Commercial size 
filter holders are available depending on project requirements. Use a 
commercial filter holder capable of supporting 47 mm or greater diameter 
filters. Commercial size filter holders contain a fluoropolymer O-ring, 
stainless steel, ceramic or fluoropolymer filter support and a final 
fluoropolymer O-ring. A filter that meets the requirements specified in 
Section 7.1.1 may be placed behind the CPM filter to reduce the pressure 
drop across the CPM filter. This support filter is not part of the PM 
sample and is not recovered with the CPM filter. At the exit of the CPM 
filter, install a fluoropolymer-coated or stainless steel encased 
thermocouple that is in contact with the gas stream.
    6.1.4 Long Stem Impinger Insert. You will need a long stem modified 
Greenburg Smith impinger insert for the water dropout impinger to 
perform the nitrogen purge of the sampling train.
    6.2 Sample Recovery Equipment.

[[Page 502]]

    6.2.1 Condensable PM Recovery. Use the following equipment to 
quantitatively determine the amount of CPM recovered from the sampling 
train.
    (a) Nitrogen purge line. You must use inert tubing and fittings 
capable of delivering at least 14 liters/min of nitrogen gas to the 
impinger train from a standard gas cylinder (see Figures 2 and 3 of 
Section 18). You may use standard 0.6 centimeters (\1/4\ inch) tubing 
and compression fittings in conjunction with an adjustable pressure 
regulator and needle valve.
    (b) Rotameter. You must use a rotameter capable of measuring gas 
flow up to 20 L/min. The rotameter must be accurate to five percent of 
full scale.
    (c) Nitrogen gas purging system. Compressed ultra-pure nitrogen, 
regulator, and filter must be capable of providing at least 14 L/min 
purge gas for one hour through the sampling train.
    (d) Amber glass bottles (500 ml).
    6.2.2 Analysis Equipment. The following equipment is necessary for 
CPM sample analysis:
    (a) Separatory Funnel. Glass, 1 liter.
    (b) Weighing Tins. 50 ml. Glass evaporation vials, fluoropolymer 
beaker liners, or aluminum weighing tins can be used.
    (c) Glass Beakers. 300 to 500 ml.
    (d) Drying Equipment. A desiccator containing anhydrous calcium 
sulfate that is maintained below 10 percent relative humidity, and a hot 
plate or oven equipped with temperature control.
    (e) Glass Pipets. 5 ml.
    (f) Burette. Glass, 0 to 100 ml in 0.1 ml graduations.
    (g) Analytical Balance. Analytical balance capable of weighing at 
least 0.0001 g (0.1 mg).
    (h) pH Meter or Colormetric pH Indicator. The pH meter or 
colormetric pH indicator (e.g., phenolphthalein) must be capable of 
determining the acidity of liquid within 0.1 pH units.
    (i) Sonication Device. The device must have a minimum sonication 
frequency of 20 kHz and be approximately four to six inches deep to 
accommodate the sample extractor tube.
    (j) Leak-Proof Sample Containers. Containers used for sample and 
blank recovery must not contribute more than 0.05 mg of residual mass to 
the CPM measurements.
    (k) Wash bottles. Any container material is acceptable, but wash 
bottles used for sample and blank recovery must not contribute more than 
0.1 mg of residual mass to the CPM measurements.

                       7.0 Reagents and Standards

    7.1 Sample Collection. To collect a sample, you will need a CPM 
filter, crushed ice, and silica gel. You must also have water and 
nitrogen gas to purge the sampling train. You will find additional 
information on each of these items in the following summaries.
    7.1.1 CPM Filter. You must use a nonreactive, nondisintegrating 
polymer filter that does not have an organic binder and does not 
contribute more than 0.5 mg of residual mass to the CPM measurements. 
The CPM filter must also have an efficiency of at least 99.95 percent 
(less than 0.05 percent penetration) on 0.3 micrometer dioctyl phthalate 
particles. You may use test data from the supplier's quality control 
program to document the CPM filter efficiency.
    7.1.2 Silica Gel. Use an indicating-type silica gel of six to 16 
mesh. You must obtain approval of the Administrator for other types of 
desiccants (equivalent or better) before you use them. Allow the silica 
gel to dry for two hours at 175 [deg]C (350 [deg]F) if it is being 
reused. You do not have to dry new silica gel if the indicator shows the 
silica gel is active for moisture collection.
    7.1.3 Water. Use deionized, ultra-filtered water that contains 1.0 
parts per million by weight (ppmw) (1 mg/L) residual mass or less to 
recover and extract samples.
    7.1.4 Crushed Ice. Obtain from the best readily available source.
    7.1.5 Nitrogen Gas. Use Ultra-High Purity compressed nitrogen or 
equivalent to purge the sampling train. The compressed nitrogen you use 
to purge the sampling train must contain no more than 1 parts per 
million by volume (ppmv) oxygen, 1 ppmv total hydrocarbons as carbon, 
and 2 ppmv moisture. The compressed nitrogen must not contribute more 
than 0.1 mg of residual mass per purge.
    7.2 Sample Recovery and Analytical Reagents. You will need acetone, 
hexane, anhydrous calcium sulfate, ammonia hydroxide, and deionized 
water for the sample recovery and analysis. Unless otherwise indicated, 
all reagents must conform to the specifications established by the 
Committee on Analytical Reagents of the American Chemical Society. If 
such specifications are not available, then use the best available 
grade. Additional information on each of these items is in the following 
paragraphs:
    7.2.1 Acetone. Use acetone that is stored in a glass bottle. Do not 
use acetone from a metal container because it normally produces a high 
residual mass in the laboratory and field reagent blanks. You must use 
acetone that has a blank value less than 1.0 ppmw (0.1 mg/100 g) 
residue.
    7.2.2 Hexane, American Chemical Society grade. You must use hexane 
that has a blank residual mass value less than 1.0 ppmw (0.1 mg/100 g) 
residue.
    7.2.3 Water. Use deionized, ultra-filtered water that contains 1 
ppmw (1 mg/L) residual mass or less to recover material caught in the 
impinger.
    7.2.4 Condensable Particulate Sample Desiccant. Use indicating-type 
anhydrous

[[Page 503]]

calcium sulfate to desiccate water and organic extract residue samples 
prior to weighing.
    7.2.5 Ammonium Hydroxide. Use National Institute of Standards and 
Technology-traceable or equivalent (0.1 N) NH4OH.
    7.2.6 Standard Buffer Solutions. Use one buffer solution with a 
neutral pH and a second buffer solution with an acid pH of no less than 
4.

       8.0 Sample Collection, Preservation, Storage, and Transport

    8.1 Qualifications. This is a complex test method. To obtain 
reliable results, you should be trained and experienced with in-stack 
filtration systems (such as, cyclones, impactors, and thimbles) and 
impinger and moisture train systems.
    8.2 Preparations. You must clean all glassware used to collect and 
analyze samples prior to field tests as described in Section 8.4 prior 
to use. Cleaned glassware must be used at the start of each new source 
category tested at a single facility. Analyze laboratory reagent blanks 
(water, acetone, and hexane) before field tests to verify low blank 
concentrations. Follow the pretest preparation instructions in Section 
8.1 of Method 5.
    8.3 Site Setup. You must follow the procedures required in Methods 
5, 17, or 201A, whichever is applicable to your test requirements 
including:
    (a) Determining the sampling site location and traverse points.
    (b) Calculating probe/cyclone blockage (as appropriate).
    (c) Verifying the absence of cyclonic flow.
    (d) Completing a preliminary velocity profile, and selecting a 
nozzle(s) and sampling rate.
    8.3.1 Sampling Site Location. Follow the standard procedures in 
Method 1 of appendix A-1 to part 60 to select the appropriate sampling 
site. Choose a location that maximizes the distance from upstream and 
downstream flow disturbances.
    8.3.2 Traverse points. Use the required number of traverse points at 
any location, as found in Methods 5, 17, or 201A, whichever is 
applicable to your test requirements. You must prevent the disturbance 
and capture of any solids accumulated on the inner wall surfaces by 
maintaining a 1-inch distance from the stack wall (0.5 inch for sampling 
locations less than 24 inches in diameter).
    8.4 Sampling Train Preparation. A schematic of the sampling train 
used in this method is shown in Figure 1 of Section 18. All glassware 
that is used to collect and analyze samples must be cleaned prior to the 
test with soap and water, and rinsed using tap water, deionized water, 
acetone, and finally, hexane. It is important to completely remove all 
silicone grease from areas that will be exposed to the hexane rinse 
during sample recovery. After cleaning, you must bake glassware at 300 
[deg]C for six hours prior to beginning tests at each source category 
sampled at a facility. As an alternative to baking glassware, a field 
train proof blank, as specified in Section 8.5.4.10, can be performed on 
the sampling train glassware that is used to collect CPM samples. Prior 
to each sampling run, the train glassware used to collect condensable PM 
must be rinsed thoroughly with deionized, ultra-filtered water that that 
contains 1 ppmw (1 mg/L) residual mass or less.
    8.4.1 Condenser and Water Dropout Impinger. Add a Method 23 type 
condenser and a condensate dropout impinger without bubbler tube after 
the final probe extension that connects the in-stack or out-of-stack hot 
filter assembly with the CPM sampling train. The Method 23 type stack 
gas condenser is described in Section 2.1.2 of Method 23. The condenser 
must be capable of cooling the stack gas to less than or equal to 30 
[deg]C (85 [deg]F).
    8.4.2 Backup Impinger. The water dropout impinger is followed by a 
modified Greenburg Smith impinger (backup impinger) with no taper (see 
Figure 1 of Section 18). Place the water dropout and backup impingers in 
an insulated box with water at less than or equal to 30 [deg]C (less 
than or equal to 85 [deg]F). At the start of the tests, the water 
dropout and backup impingers must be clean, without any water or reagent 
added.
    8.4.3 CPM Filter. Place a filter holder with a filter meeting the 
requirements in Section 7.1.1 after the backup impinger. The connection 
between the CPM filter and the moisture trap impinger must include a 
thermocouple fitting that provides a leak-free seal between the 
thermocouple and the stack gas. (Note: A thermocouple well is not 
sufficient for this purpose because the fluoropolymer- or steel-encased 
thermocouple must be in contact with the sample gas.)
    8.4.4 Moisture Traps. You must use a modified Greenburg-Smith 
impinger containing 100 ml of water, or the alternative described in 
Method 5 of appendix A-3 to part 60, followed by an impinger containing 
silica gel to collect moisture that passes through the CPM filter. You 
must maintain the gas temperature below 20 [deg]C (68 [deg]F) at the 
exit of the moisture traps.
    8.4.5 Silica Gel Trap. Place 200 to 300 g of silica gel in each of 
several air-tight containers. Weigh each container, including silica 
gel, to the nearest 0.5 g, and record this weight on the filterable 
particulate data sheet. As an alternative, the silica gel need not be 
preweighed, but may be weighed directly in its impinger or sampling 
holder just prior to train assembly.
    8.4.6 Leak-Check (Pretest). Use the procedures outlined in Method 5 
of appendix A-3 to part 60, Method 17 of appendix A-6 to part 60, or 
Method 201A of appendix M to this part

[[Page 504]]

as appropriate to leak check the entire sampling system. Specifically, 
perform the following procedures:
    8.4.6.1 Sampling train. You must pretest the entire sampling train 
for leaks. The pretest leak-check must have a leak rate of not more than 
0.02 actual cubic feet per minute or 4 percent of the average sample 
flow during the test run, whichever is less. Additionally, you must 
conduct the leak-check at a vacuum equal to or greater than the vacuum 
anticipated during the test run. Enter the leak-check results on the 
field test data sheet for the filterable particulate method. (Note: 
Conduct leak-checks during port changes only as allowed by the 
filterable particulate method used with this method.)
    8.4.6.2 Pitot tube assembly. After you leak-check the sample train, 
perform a leak-check of the pitot tube assembly. Follow the procedures 
outlined in Section 8.4.1 of Method 5.
    8.5 Sampling Train Operation. Operate the sampling train as 
described in the filterable particulate sampling method (i.e., Method 5 
of appendix A-3 to part 60, Method 17 of appendix A-6 to part 60, or 
Method 201A of appendix M to this part) with the following additions or 
exceptions:
    8.5.1 Impinger and CPM Filter Assembly.
    8.5.1.1 Monitor the moisture condensation in the knockout and backup 
impingers. If the accumulated water from moisture condensation 
overwhelms the knockout impinger, i.e., the water level is more than 
approximately one-half the capacity of the knockout impinger, or if 
water accumulates in the backup impinger sufficient to cover the 
impinger insert tip, then you may interrupt the sampling run, recover 
and weigh the moisture accumulated in the knockout and backup impinger, 
reassemble and leak check the sampling train, and resume the sampling 
run. You must purge the water collected during the test interruption as 
soon as practical following the procedures in Section 8.5.3.
    8.5.1.2 You must include the weight or volume of the moisture in 
your moisture calculation and you must combine the recovered water with 
the appropriate sample fraction for subsequent CPM analysis.
    8.5.1.3 Use the field data sheet for the filterable particulate 
method to record the CPM filter temperature readings at the beginning of 
each sample time increment and when sampling is halted. Maintain the CPM 
filter greater than 20 [deg]C (greater than 65 [deg]F) but less than or 
equal to 30 [deg]C (less than or equal to 85 [deg]F) during sample 
collection. (Note: Maintain the temperature of the CPM filter assembly 
as close to 30 [deg]C (85 [deg]F) as feasible.)
    8.5.2 Leak-Check Probe/Sample Train Assembly (Post-Test). Conduct 
the leak rate check according to the filterable particulate sampling 
method used during sampling. If required, conduct the leak-check at a 
vacuum equal to or greater than the maximum vacuum achieved during the 
test run. If the leak rate of the sampling train exceeds 0.02 actual 
cubic feet per minute or four percent of the average sampling rate 
during the test run (whichever is less), then the run is invalid and you 
must repeat it.
    8.5.3 Post-Test Nitrogen Purge. As soon as possible after the post-
test leak-check, detach the probe, any cyclones, and in-stack or hot 
filters from the condenser and impinger train. If no water was collected 
before the CPM filter, then you may skip the remaining purge steps and 
proceed with sample recovery (see Section 8.5.4). You may purge the CPM 
sampling train using the sampling system meter box and vacuum pump or by 
passing nitrogen through the train under pressure. For either type of 
purge, you must first attach the nitrogen supply line to a purged inline 
filter.
    8.5.3.1 If you choose to conduct a pressurized nitrogen purge at the 
completion of CPM sample collection, you may purge the entire CPM sample 
collection train from the condenser inlet to the CPM filter holder 
outlet or you may quantitatively transfer the water collected in the 
condenser and the water dropout impinger to the backup impinger and 
purge only the backup impinger and the CPM filter. You must measure the 
water in the knockout and backup impingers and record the volume or 
weight as part of the moisture collected during sampling as specified in 
Section 8.5.3.4.
    8.5.3.1.1 If you choose to conduct a purge of the entire CPM 
sampling train, you must replace the short stem impinger insert in the 
knock out impinger with a standard modified Greenburg Smith impinger 
insert.
    8.5.3.1.2 If you choose to combine the knockout and backup impinger 
catch prior to purge, you must purge the backup impinger and CPM filter 
holder.
    8.5.3.1.3 If the tip of the impinger insert does not extend below 
the water level (including the water transferred from the first impinger 
if this option was chosen), you must add a measured amount of degassed, 
deionized ultra-filtered water that contains 1 ppmw (1 mg/L) residual 
mass or less until the impinger tip is at least 1 centimeter below the 
surface of the water. You must record the amount of water added to the 
water dropout impinger (Vp)(see Figure 4 of Section 18) to correct the 
moisture content of the effluent gas. (Note: Prior to use, water must be 
degassed using a nitrogen purge bubbled through the water for at least 
15 minutes to remove dissolved oxygen).
    8.5.3.1.4 To perform the nitrogen purge using positive pressure 
nitrogen flow, you must start with no flow of gas through the clean 
purge line and fittings. Connect the filter outlet to the input of the 
impinger train and disconnect the vacuum line from the

[[Page 505]]

exit of the silica moisture collection impinger (see Figure 3 of Section 
18). You may purge only the CPM train by disconnecting the moisture 
train components if you measure moisture in the field prior to the 
nitrogen purge. You must increase the nitrogen flow gradually to avoid 
over-pressurizing the impinger array. You must purge the CPM train at a 
minimum of 14 liters per minute for at least one hour. At the conclusion 
of the purge, turn off the nitrogen delivery system.
    8.5.3.2 If you choose to conduct a nitrogen purge on the complete 
CPM sampling train using the sampling system meter box and vacuum pump, 
replace the short stem impinger insert with a modified Greenberg Smith 
impinger insert. The impinger tip length must extend below the water 
level in the impinger catch.
    (a) You must conduct the purge on the complete CPM sampling train 
starting at the inlet of the condenser. If insufficient water was 
collected, you must add a measured amount of degassed, deionized ultra-
filtered water that contains 1 ppmw (1 mg/L) residual mass or less until 
the impinger tip is at least 1 centimeter below the surface of the 
water. You must record the amount of water added to the water dropout 
impinger (Vp) (see Figure 4 of Section 18) to correct the 
moisture content of the effluent gas. (Note: Prior to use, water must be 
degassed using a nitrogen purge bubbled through the water for at least 
15 minutes to remove dissolved oxygen.)
    (b) You must start the purge using the sampling train vacuum pump 
with no flow of gas through the clean purge line and fittings. Connect 
the filter outlet to the input of the impinger train (see Figure 2 of 
Section 18). To avoid over- or under-pressurizing the impinger array, 
slowly commence the nitrogen gas flow through the line while 
simultaneously opening the meter box pump valve(s). Adjust the pump 
bypass and/or nitrogen delivery rates to obtain the following 
conditions: 14 liters/min or [Delta]H@ and a positive overflow rate 
through the rotameter of less than 2 liters/min. The presence of a 
positive overflow rate guarantees that the nitrogen delivery system is 
operating at greater than ambient pressure and prevents the possibility 
of passing ambient air (rather than nitrogen) through the impingers. 
Continue the purge under these conditions for at least one hour, 
checking the rotameter and [Delta]H@ value(s) at least every 15 minutes. 
At the conclusion of the purge, simultaneously turn off the delivery and 
pumping systems.
    8.5.3.3 During either purge procedure, continue operation of the 
condenser recirculation pump, and heat or cool the water surrounding the 
first two impingers to maintain the gas temperature measured at the exit 
of the CPM filter greater than 20 [deg]C (greater than 65 [deg]F), but 
less than or equal to 30 [deg]C (less than or equal to 85 [deg]F). If 
the volume of liquid collected in the moisture traps has not been 
determined prior to conducting the nitrogen purge, maintain the 
temperature of the moisture traps following the CPM filter to prevent 
removal of moisture during the purge. If necessary, add more ice during 
the purge to maintain the gas temperature measured at the exit of the 
silica gel impinger below 20 [deg]C (68 [deg]F). Continue the purge 
under these conditions for at least one hour, checking the rotameter and 
[Delta]H@ value(s) periodically. At the conclusion of the purge, 
simultaneously turn off the delivery and pumping systems.
    8.5.3.4 Weigh the liquid, or measure the volume of the liquid 
collected in the dropout, impingers, and silica trap if this has not 
been done prior to purging the sampling train. Measure the liquid in the 
water dropout impinger to within 1 ml using a clean graduated cylinder 
or by weighing it to within 0.5 g using a balance. Record the volume or 
weight of liquid present to be used to calculate the moisture content of 
the effluent gas in the field log notebook.
    8.5.3.5 If a balance is available in the field, weigh the silica 
impinger to within 0.5 g. Note the color of the indicating silica gel in 
the last impinger to determine whether it has been completely spent, and 
make a notation of its condition in the field log notebook.
    8.5.4 Sample Recovery.
    8.5.4.1 Recovery of filterable PM. Recovery of filterable PM 
involves the quantitative transfer of particles according to the 
filterable particulate sampling method (i.e., Method 5 of appendix A-3 
to part 60, Method 17 of appendix A-6 to part 60, or Method 201A of 
appendix M to this part).
    8.5.4.2 CPM Container 1, Aqueous liquid impinger contents. 
Quantitatively transfer liquid from the dropout and the backup impingers 
prior to the CPM filter into a clean, leak-proof container labeled with 
test identification and ``CPM Container 1, Aqueous Liquid Impinger 
Contents.'' Rinse all sampling train components including the back half 
of the filterable PM filter holder, the probe extension, condenser, each 
impinger and the connecting glassware, and the front half of the CPM 
filter housing twice with water. Recover the rinse water, and add it to 
CPM Container 1. Mark the liquid level on the container.
    8.5.4.3 CPM Container 2, Organic rinses. Follow the water rinses of 
the back half of the filterable PM filter holder, probe extension, 
condenser, each impinger, and all of the connecting glassware and front 
half of the CPM filter with an acetone rinse. Recover the acetone rinse 
into a clean, leak-proof container labeled with test identification and 
``CPM Container 2, Organic Rinses.'' Then repeat the entire rinse 
procedure with two rinses of hexane, and save the hexane rinses in the 
same container as the acetone

[[Page 506]]

rinse (CPM Container 2). Mark the liquid level on the jar.
    8.5.4.4 CPM Container 3, CPM filter sample. Use tweezers and/or 
clean disposable surgical gloves to remove the filter from the CPM 
filter holder. Place the filter in the Petri dish labeled with test 
identification and ``CPM Container 3, Filter Sample.''
    8.5.4.5 CPM Container 4, Cold impinger water. You must weigh or 
measure the volume of the contents of CPM Container 4 either in the 
field or during sample analysis (see Section 11.2.4). If the water from 
the cold impinger has been weighed in the field, it can be discarded. 
Otherwise, quantitatively transfer liquid from the cold impinger that 
follows the CPM filter into a clean, leak-proof container labeled with 
test identification and ``CPM Container 4, Cold Water Impinger.'' Mark 
the liquid level on the container. CPM Container 4 holds the remainder 
of the liquid water from the emission gases.
    8.5.4.6 CPM Container 5, Silica gel absorbent. You must weigh the 
contents of CPM Container 5 in the field or during sample analysis (see 
Section 11.2.5). If the silica gel has been weighed in the field to 
measure water content, then it can be discarded or recovered for reuse. 
Otherwise, transfer the silica gel to its original container labeled 
with test identification and ``CPM Container 5, Silica Gel Absorbent'' 
and seal. You may use a funnel to make it easier to pour the silica gel 
without spilling. You may also use a rubber policeman as an aid in 
removing the silica gel from the impinger. It is not necessary to remove 
the small amount of silica gel dust particles that may adhere to the 
impinger wall and are difficult to remove. Since the gain in weight is 
to be used for moisture calculations, do not use any water or other 
liquids to transfer the silica gel.
    8.5.4.7 CPM Container 6, Acetone field reagent blank. Take 
approximately 200 ml of the acetone directly from the wash bottle you 
used for sample recovery and place it in a clean, leak-proof container 
labeled with test identification and ``CPM Container 6, Acetone Field 
Reagent Blank'' (see Section 11.2.6 for analysis). Mark the liquid level 
on the container. Collect one acetone field reagent blank from the 
lot(s) of solvent used for the test.
    8.5.4.8 CPM Container 7, Water field reagent blank. Take 
approximately 200 ml of the water directly from the wash bottle you used 
for sample recovery and place it in a clean, leak-proof container 
labeled with test identification and ``CPM Container 7, Water Field 
Reagent Blank'' (see Section 11.2.7 for analysis). Mark the liquid level 
on the container. Collect one water field reagent blank from the lot(s) 
of water used for the test.
    8.5.4.9 CPM Container 8, Hexane field reagent blank. Take 
approximately 200 ml of the hexane directly from the wash bottle you 
used for sample recovery and place it in a clean, leak-proof container 
labeled with test identification and ``CPM Container 8, Hexane Field 
Reagent Blank'' (see Section 11.2.8 for analysis). Mark the liquid level 
on the container. Collect one hexane field reagent blank from the lot(s) 
of solvent used for the test.
    8.5.4.10 Field train proof blank. If you did not bake the sampling 
train glassware as specified in Section 8.4, you must conduct a field 
train proof blank as specified in Sections 8.5.4.11 and 8.5.4.12 to 
demonstrate the cleanliness of sampling train glassware.
    8.5.4.11 CPM Container 9, Field train proof blank, inorganic 
rinses. Prior to conducting the emission test, rinse the probe 
extension, condenser, each impinger and the connecting glassware, and 
the front half of the CPM filter housing twice with water. Recover the 
rinse water and place it in a clean, leak-proof container labeled with 
test identification and ``CPM Container 9, Field Train Proof Blank, 
Inorganic Rinses.'' Mark the liquid level on the container.
    8.5.4.12 CPM Container 10, Field train proof blank, organic rinses. 
Follow the water rinse of the probe extension, condenser, each impinger 
and the connecting glassware, and the front half of the CPM filter 
housing with an acetone rinse. Recover the acetone rinse into a clean, 
leak-proof container labeled with test identification and ``CPM 
Container 10, Field Train Proof Blank, Organic Rinses.'' Then repeat 
the entire rinse procedure with two rinses of hexane and save the hexane 
rinses in the same container as the acetone rinse (CPM Container 10). 
Mark the liquid level on the container.
    8.5.5 Transport procedures. Containers must remain in an upright 
position at all times during shipping. You do not have to ship the 
containers under dry or blue ice. However, samples must be maintained at 
or below 30 [deg]C (85 [deg]F) during shipping.

                           9.0 Quality Control

    9.1 Daily Quality Checks. You must perform daily quality checks of 
field log notebooks and data entries and calculations using data quality 
indicators from this method and your site-specific test plan. You must 
review and evaluate recorded and transferred raw data, calculations, and 
documentation of testing procedures. You must initial or sign log 
notebook pages and data entry forms that were reviewed.
    9.2 Calculation Verification. Verify the calculations by 
independent, manual checks. You must flag any suspect data and identify 
the nature of the problem and potential effect on data quality. After 
you complete the test, prepare a data summary and compile all the 
calculations and raw data sheets.
    9.3 Conditions. You must document data and information on the 
process unit tested,

[[Page 507]]

the particulate control system used to control emissions, any non-
particulate control system that may affect particulate emissions, the 
sampling train conditions, and weather conditions. Discontinue the test 
if the operating conditions may cause non-representative particulate 
emissions.
    9.4 Field Analytical Balance Calibration Check. Perform calibration 
check procedures on field analytical balances each day that they are 
used. You must use National Institute of Standards and Technology 
(NIST)-traceable weights at a mass approximately equal to the weight of 
the sample plus container you will weigh.
    9.5 Glassware. Use class A volumetric glassware for titrations, or 
calibrate your equipment against NIST-traceable glassware.
    9.6 Laboratory Analytical Balance Calibration Check. Check the 
calibration of your laboratory analytical balance each day that you 
weigh CPM samples. You must use NIST Class S weights at a mass 
approximately equal to the weight of the sample plus container you will 
weigh.
    9.7 Laboratory Reagent Blanks. You should run blanks of water, 
acetone, and hexane used for field recovery and sample analysis. Analyze 
at least one sample (150 ml minimum) of each lot of reagents that you 
plan to use for sample recovery and analysis before you begin testing. 
These blanks are not required by the test method, but running blanks 
before field use is advisable to verify low blank concentrations, 
thereby reducing the potential for a high field blank on test samples.
    9.8 Field Reagent Blanks. You should run at least one field reagent 
blank of water, acetone, and hexane you use for field recovery. These 
blanks are not required by the test method, but running independent 
field reagent blanks is advisable to verify that low blank 
concentrations were maintained during field solvent use and demonstrate 
that reagents have not been contaminated during field tests.
    9.9 Field Train Proof Blank. If you are not baking glassware as 
specified in Section 8.4, you must recover a minimum of one field train 
proof blank for the sampling train used for testing each new source 
category at a single facility. You must assemble the sampling train as 
it will be used for testing. You must recover the field train proof 
blank samples as described in Section 8.5.4.11 and 8.5.4.12.
    9.10 Field Train Recovery Blank. You must recover a minimum of one 
field train blank for each source category tested at the facility. You 
must recover the field train blank after the first or second run of the 
test. You must assemble the sampling train as it will be used for 
testing. Prior to the purge, you must add 100 ml of water to the first 
impinger and record this data on Figure 4. You must purge the assembled 
train as described in section 8.5.3. You must recover field train blank 
samples as described in section 8.5.4. From the field sample weight, you 
will subtract the condensable particulate mass you determine with this 
blank train or 0.002 g (2.0 mg), whichever is less.

                  10.0 Calibration and Standardization

    Maintain a field log notebook of all condensable particulate 
sampling and analysis calibrations. Include copies of the relevant 
portions of the calibration and field logs in the final test report.
    10.1 Thermocouple Calibration. You must calibrate the thermocouples 
using the procedures described in Section 10.3.1 of Method 2 of appendix 
A-1 to part 60 or Alternative Method 2, Thermocouple Calibration (ALT-
011) (http://www.epa.gov/ttn/emc). Calibrate each temperature sensor at 
a minimum of three points over the anticipated range of use against a 
NIST-traceable thermometer. Alternatively, a reference thermocouple and 
potentiometer calibrated against NIST standards can be used.
    10.2 Ammonium Hydroxide. The 0.1 N NH4OH used for 
titrations in this method is made as follows: Add 7 ml of concentrated 
(14.8 M) NH4OH to l liter of water. Standardize against 
standardized 0.1 N H2SO4, and calculate the exact 
normality using a procedure parallel to that described in Section 10.5 
of Method 6 of appendix A-4 to 40 CFR part 60. Alternatively, purchase 
0.1 N NH4OH that has been standardized against a NIST 
reference material. Record the normality on the CPM Work Table (see 
Figure 6 of Section 18).
    10.3 Field Balance Calibration Check. Check the calibration of the 
balance used to weigh impingers with a weight that is at least 500g or 
within 50g of a loaded impinger. The weight must be ASTM E617-13 
``Standard Specification for Laboratory Weights and Precision Mass 
Standards'' Class 6 (or better). Daily before use, the field balance 
must measure the weight within  0.5g of the 
certified mass. If the daily balance calibration check fails, perform 
corrective measures and repeat the check before using balance.
    10.4 Analytical Balance Calibration. Perform a multipoint 
calibration (at least five points spanning the operational range) of the 
analytical balance before the first use, and semiannually thereafter. 
The calibration of the analytical balance must be conducted using ASTM 
E617-13 ``Standard Specification for Laboratory Weights and Precision 
Mass Standards'' Class 2 (or better) tolerance weights. Audit the 
balance each day it is used for gravimetric measurements by weighing at 
least one ASTM E617-13 Class 2 tolerance (or better) calibration weight 
that corresponds to 50 to 150 percent of the weight of one filter or 
between 1g and 5g. If the scale

[[Page 508]]

cannot reproduce the value of the calibration weight to within 0.5mg of 
the certified mass, perform corrective measures, and conduct the 
multipoint calibration before use.

                       11.0 Analytical Procedures

    11.1 Analytical Data Sheets. (a) Record the filterable particulate 
field data on the appropriate (i.e., Method 5, 17, or 201A) analytical 
data sheets. Alternatively, data may be recorded electronically using 
software applications such as the Electronic Reporting Tool available at 
http://www.epa.gov/ttn/chief/ert/ert_tool.html. Record the condensable 
particulate data on the CPM Work Table (see Figure 6 of Section 18).
    (b) Measure the liquid in all containers either volumetrically to 
1 ml or gravimetrically to 0.5 g. Confirm on the filterable particulate analytical 
data sheet whether leakage occurred during transport. If a noticeable 
amount of leakage has occurred, either void the sample or use methods 
(subject to the approval of the Administrator) to correct the final 
results.
    11.2 Condensable PM Analysis. See the flow chart in Figure 7 of 
Section 18 for the steps to process and combine fractions from the CPM 
train.
    11.2.1 Container 3, CPM Filter Sample. If the sample was collected 
by Method 17 or Method 201A with a stack temperature below 30 [deg]C (85 
[deg]F), transfer the filter and any loose PM from the sample container 
to a tared glass weighing dish. (See Section 3.0 for a definition of 
constant weight.) Desiccate the sample for 24 hours in a desiccator 
containing anhydrous calcium sulfate. Weigh to a constant weight and 
report the results to the nearest 0.1 mg. [Note: In-stack filter samples 
collected at 30 [deg]C (85 [deg]F) may include both filterable insoluble 
particulate and condensable particulate. The nozzle and front half wash 
and filter collected at or below 30 [deg]C (85 [deg]F) may not be heated 
and must be maintained at or below 30 [deg]C (85 [deg]F).] If the sample 
was collected by Method 202, extract the CPM filter as follows:
    11.2.1.1 Extract the water soluble (aqueous or inorganic) CPM from 
the CPM filter by folding the filter in quarters and placing it into a 
50-ml extraction tube. Add sufficient deionized, ultra-filtered water to 
cover the filter (e.g., 10 ml of water). Place the extractor tube into a 
sonication bath and extract the water-soluble material for a minimum of 
two minutes. Combine the aqueous extract with the contents of Container 
1. Repeat this extraction step twice for a total of three extractions.
    11.2.1.2 Extract the organic soluble CPM from the CPM filter by 
adding sufficient hexane to cover the filter (e.g., 10 ml of hexane). 
Place the extractor tube into a sonication bath and extract the organic 
soluble material for a minimum of two minutes. Combine the organic 
extract with the contents of Container 2. Repeat this extraction step 
twice for a total of three extractions.
    11.2.2 CPM Container 1, Aqueous Liquid Impinger Contents. Analyze 
the water soluble CPM in Container 1 as described in this section. 
Place the contents of Container 1 into a separatory funnel. Add 
approximately 30 ml of hexane to the funnel, mix well, and pour off the 
upper organic phase. Repeat this procedure twice with 30 ml of hexane 
each time combining the organic phase from each extraction. Each time, 
leave a small amount of the organic/hexane phase in the separatory 
funnel, ensuring that no water is collected in the organic phase. This 
extraction should yield about 90 ml of organic extract. Combine the 
organic extract from Container 1 with the organic train rinse in 
Container 2.
    11.2.2.1 Determine the inorganic fraction weight. Transfer the 
aqueous fraction from the extraction to a clean 500-ml or smaller 
beaker. Evaporate to no less than 10 ml liquid on a hot plate or in the 
oven at 105 [deg]C and allow to dry at room temperature (not to exceed 
30 [deg]C (85 [deg]F)). You must ensure that water and volatile acids 
have completely evaporated before neutralizing nonvolatile acids in the 
sample. Following evaporation, desiccate the residue for 24 hours in a 
desiccator containing anhydrous calcium sulfate. Weigh at intervals of 
at least 6 hours to a constant weight. (See section 3.0 for a definition 
of constant weight.) Report results to the nearest 0.1 mg on the CPM 
Work Table (see Figure 6 of section 18) and proceed directly to section 
11.2.3. If the residue cannot be weighed to constant weight, re-dissolve 
the residue in 100 ml of deionized distilled ultra-filtered water that 
contains 1 ppmw (1 mg/L) residual mass or less and continue to section 
11.2.2.2.
    11.2.2.2 Use titration to neutralize acid in the sample and remove 
water of hydration. If used, calibrate the pH meter with the neutral and 
acid buffer solutions. Then titrate the sample with 0.1N 
NH4OH to a pH of 7.0, as indicated by the pH meter or 
colorimetric indicator. Record the volume of titrant used on the CPM 
Work Table (see Figure 6 of section 18).
    11.2.2.3 Using a hot plate or an oven at 105 [deg]C, evaporate the 
aqueous phase to approximately 10 ml. Quantitatively transfer the beaker 
contents to a clean, 50-ml pre-tared weighing tin and evaporate to 
dryness at room temperature (not to exceed 30 [deg]C (85 [deg]F)) and 
pressure in a laboratory hood. Following evaporation, desiccate the 
residue for 24 hours in a desiccator containing anhydrous calcium 
sulfate. Weigh at intervals of at least 6 hours to a constant weight. 
(See section 3.0 for a definition of constant weight.) Report results to 
the nearest 0.1 mg on the CPM Work Table (see Figure 6 of section 18).

[[Page 509]]

    11.2.2.4 Calculate the correction factor to subtract the 
NH4+ retained in the sample using Equation 1 in 
section 12.
    11.2.3 CPM Container 2, Organic Fraction Weight Determination. 
Analyze the organic soluble CPM in Container 2 as described in this 
section. Place the organic phase in a clean glass beaker. Evaporate the 
organic extract at room temperature (not to exceed 30 [deg]C (85 
[deg]F)) and pressure in a laboratory hood to not less than 10 ml. 
Quantitatively transfer the beaker contents to a clean 50-ml pre-tared 
weighing tin and evaporate to dryness at room temperature (not to exceed 
30 [deg]C (85 [deg]F)) and pressure in a laboratory hood. Following 
evaporation, desiccate the organic fraction for 24 hours in a desiccator 
containing anhydrous calcium sulfate. Weigh at intervals of at least six 
hours to a constant weight (i.e., less than or equal to 0.5 mg change 
from previous weighing), and report results to the nearest 0.1 mg on the 
CPM Work Table (see Figure 6 of Section 18).
    11.2.4 CPM Container 4, Cold Impinger Water. If the amount of water 
has not been determined in the field, note the level of liquid in the 
container, and confirm on the filterable particulate analytical data 
sheet whether leakage occurred during transport. If a noticeable amount 
of leakage has occurred, either void the sample or use methods (subject 
to the approval of the Administrator) to correct the final results. 
Measure the liquid in Container 4 either volumetrically to 1 ml or gravimetrically to 0.5 g, 
and record the volume or weight on the filterable particulate analytical 
data sheet of the filterable PM test method.
    11.2.5 CPM Container 5, Silica Gel Absorbent. Weigh the spent 
silica gel (or silica gel plus impinger) to the nearest 0.5 g using a 
balance. This step may be conducted in the field. Record the weight on 
the filterable particulate analytical data sheet of the filterable PM 
test method.
    11.2.6 Container 6, Acetone Field Reagent Blank. Use 150 ml of 
acetone from the blank container used for this analysis. Transfer 150 ml 
of the acetone to a clean 250-ml beaker. Evaporate the acetone at room 
temperature (not to exceed 30 [deg]C (85 [deg]F)) and pressure in a 
laboratory hood to approximately 10 ml. Quantitatively transfer the 
beaker contents to a clean 50-ml pre-tared weighing tin, and evaporate 
to dryness at room temperature (not to exceed 30 [deg]C (85 [deg]F)) and 
pressure in a laboratory hood. Following evaporation, desiccate the 
residue for 24 hours in a desiccator containing anhydrous calcium 
sulfate. Weigh at intervals of at least six hours to a constant weight 
(i.e., less than or equal to 0.5 mg change from previous weighing), and 
report results to the nearest 0.1 mg on Figure 4 of Section 19.
    11.2.7 Water Field Reagent Blank, Container 7. Use 150 ml of the 
water from the blank container for this analysis. Transfer the water to 
a clean 250-ml beaker, and evaporate to approximately 10 ml liquid in 
the oven at 105 [deg]C. Quantitatively transfer the beaker contents to a 
clean 50 ml pre-tared weighing tin and evaporate to dryness at room 
temperature (not to exceed 30 [deg]C (85 [deg]F)) and pressure in a 
laboratory hood. Following evaporation, desiccate the residue for 24 
hours in a desiccator containing anhydrous calcium sulfate. Weigh at 
intervals of at least six hours to a constant weight (i.e., less than or 
equal to 0.5 mg change from previous weighing) and report results to the 
nearest 0.1 mg on Figure 4 of Section 18.
    11.2.8 Hexane Field Reagent Blank, Container 8. Use 150 ml of 
hexane from the blank container for this analysis. Transfer 150 ml of 
the hexane to a clean 250-ml beaker. Evaporate the hexane at room 
temperature (not to exceed 30 [deg]C (85 [deg]F)) and pressure in a 
laboratory hood to approximately 10 ml. Quantitatively transfer the 
beaker contents to a clean 50-ml pre-tared weighing tin and evaporate to 
dryness at room temperature (not to exceed 30 [deg]C (85 [deg]F)) and 
pressure in a laboratory hood. Following evaporation, desiccate the 
residue for 24 hours in a desiccator containing anhydrous calcium 
sulfate. Weigh at intervals of at least six hours to a constant weight 
(i.e., less than or equal to 0.5 mg change from previous weighing), and 
report results to the nearest 0.1 mg on Figure 4 of Section 18.

                   12.0 Calculations and Data Analysis

    12.1 Nomenclature. Report results in International System of Units 
(SI units) unless the regulatory authority for testing specifies English 
units. The following nomenclature is used.

    [Delta]H@ = Pressure drop across orifice at flow rate of 
0.75 SCFM at standard conditions, inches of water column (Note: Specific 
to each orifice and meter box).
17.03 = mg/milliequivalents for ammonium ion.
ACFM = Actual cubic feet per minute.
Ccpm = Concentration of the condensable PM in the stack gas, 
          dry basis, corrected to standard conditions, milligrams/dry 
          standard cubic foot.
mc = Mass of the NH4+ added to sample 
          to form ammonium sulfate, mg.
mcpm = Mass of the total condensable PM, mg.
mfb = Mass of total CPM in field train recovery blank, mg.
mg = Milligrams.
mg/L = Milligrams per liter.
mi = Mass of inorganic CPM, mg.
mib = Mass of inorganic CPM in field train recovery blank, 
          mg.
mo = Mass of organic CPM, mg.
mob = Mass of organic CPM in field train blank, mg.

[[Page 510]]

mr = Mass of dried sample from inorganic fraction, mg.
N = Normality of ammonium hydroxide titrant.
ppmv = Parts per million by volume.
ppmw = Parts per million by weight.
Vm(std) = Volume of gas sample measured by the dry gas meter, 
          corrected to standard conditions, dry standard cubic meter 
          (dscm) or dry standard cubic foot (dscf) as defined in 
          Equation 5-1 of Method 5.
Vt = Volume of NH4OH titrant, ml.
Vp = Volume of water added during train purge.

    12.2 Calculations. Use the following equations to complete the 
calculations required in this test method. Enter the appropriate results 
from these calculations on the CPM Work Table (see Figure 6 of Section 
18).
    12.2.1 Mass of ammonia correction. Correction for ammonia added 
during titration of 100 ml aqueous CPM sample. This calculation assumes 
no waters of hydration.
[GRAPHIC] [TIFF OMITTED] TR21DE10.058

    12.2.2 Mass of the Field Train Recovery Blank (mg). Per Section 
9.10, the mass of the field train recovery blank, mfb, shall 
not exceed 2.0 mg.
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    12.2.3 Mass of Inorganic CPM (mg).
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    12.2.4 Total Mass of CPM (mg).
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    12.2.5 Concentration of CPM (mg/dscf).
    [GRAPHIC] [TIFF OMITTED] TR21DE10.062
    
    12.3 Emissions Test Report. You must prepare a test report following 
the guidance in EPA Guidance Document 043 (Preparation and Review of 
Test Reports. December 1998).

                         13.0 Method Performance

    An EPA field evaluation of the revised Method 202 showed the 
following precision in the results: approximately 4 mg for total CPM, 
approximately 0.5 mg for organic CPM, and approximately 3.5 mg for 
inorganic CPM.

                        14.0 Pollution Prevention

    [Reserved]

                          15.0 Waste Management

    Solvent and water are evaporated in a laboratory hood during 
analysis. No liquid waste is generated in the performance of this 
method. Organic solvents used to clean sampling equipment should be 
managed as RCRA organic waste.

[[Page 511]]

                       16.0 Alternative Procedures

    Alternative Method 2, Thermocouple Calibration (ALT-011) for the 
thermocouple calibration can be found at http://www.epa.gov/ttn/emc/
approalt.html.

                             17.0 References

    (1) Commonwealth of Pennsylvania, Department of Environmental 
Resources. 1960. Chapter 139, Sampling and Testing (Title 25, Rules and 
Regulations, part I, Department of Environmental Resources, Subpart C, 
Protection of Natural Resources, Article III, Air Resources). January 8, 
1960.
    (2) DeWees, W.D. and K.C. Steinsberger. 1989. ``Method Development 
and Evaluation of Draft Protocol for Measurement of Condensable 
Particulate Emissions.'' Draft Report. November 17, 1989.
    (3) DeWees, W.D., K.C. Steinsberger, G.M. Plummer, L.T. Lay, G.D. 
McAlister, and R.T. Shigehara. 1989. ``Laboratory and Field Evaluation 
of EPA Method 5 Impinger Catch for Measuring Condensable Matter from 
Stationary Sources.'' Paper presented at the 1989 EPA/AWMA International 
Symposium on Measurement of Toxic and Related Air Pollutants. Raleigh, 
North Carolina. May 1-5, 1989.
    (4) Electric Power Research Institute (EPRI). 2008. ``Laboratory 
Comparison of Methods to Sample and Analyze Condensable PM.'' EPRI 
Agreement EP-P24373/C11811 Condensable Particulate Methods: EPRI 
Collaboration with EPA, October 2008.
    (5) Nothstein, Greg. Masters Thesis. University of Washington. 
Department of Environmental Health. Seattle, Washington.
    (6) Richards, J., T. Holder, and D. Goshaw. 2005. ``Optimized Method 
202 Sampling Train to Minimize the Biases Associated with Method 202 
Measurement of Condensable PM Emissions.'' Paper presented at Air & 
Waste Management Association Hazardous Waste Combustion Specialty 
Conference. St. Louis, Missouri. November 2-3, 2005.
    (7) Texas Air Control Board, Laboratory Division. 1976. 
``Determination of Particulate in Stack Gases Containing Sulfuric Acid 
and/or Sulfur Dioxide.'' Laboratory Methods for Determination of Air 
Pollutants. Modified December 3, 1976.
    (8) Puget Sound Air Pollution Control Agency, Engineering Division. 
1983. ``Particulate Source Test Procedures Adopted by Puget Sound Air 
Pollution Control Agency Board of Directors.'' Seattle, Washington. 
August 11, 1983.
    (9) U.S. Environmental Protection Agency, Federal Reference Methods 
1 through 5 and Method 17, 40 CFR 60, appendix A-1 through A-3 and A-6.
    (10) U.S. Environmental Protection Agency. 2008. ``Evaluation and 
Improvement of Condensable PM Measurement,'' EPA Contract No. EP-D-07-
097, Work Assignment 2-03, October 2008.
    (11) U.S. Environmental Protection Agency. 2005. ``Laboratory 
Evaluation of Method 202 to Determine Fate of SO2 in Impinger 
Water,'' EPA Contract No. 68-D-02-061, Work Assignment 3-14, September 
30, 2005.
    (12) U.S. Environmental Protection Agency. 2010. Field valuation of 
an Improved Method for Sampling and Analysis of Filterable and 
Condensable Particulate Matter. Office of Air Quality Planning and 
Standards, Sector Policy and Program Division Monitoring Policy Group. 
Research Triangle Park, NC 27711.
    (13) Wisconsin Department of Natural Resources. 1988. Air Management 
Operations Handbook, Revision 3. January 11, 1988.

         18.0 Tables, Diagrams, Flowcharts, and Validation Data

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[[Page 518]]



     Method 203A--Visual Determination of Opacity of Emissions from 
            Stationary Sources for Time-Averaged Regulations

                        1.0 Scope and Application

                          What is Method 203A?

    Method 203A is an example test method suitable for State 
Implementation Plans (SIP) and is applicable to the determination of the 
opacity of emissions from sources of visible emissions for time-averaged 
regulations. A time-averaged regulation is any regulation that requires 
averaging visible emission data to determine the opacity of visible 
emissions over a specific time period.
    Method 203A is virtually identical to EPA's Method 9 of 40 CFR Part 
60, Appendix A, except for the data-reduction procedures, which provide 
for averaging times other than 6 minutes. Therefore, using Method 203A 
with a 6-minute averaging time would be the same as following EPA Method 
9. The certification procedures for this method are identical to those 
provided in Method 9 and are provided here, in full, for clarity and 
convenience. An example visible emission observation form and 
instructions for its use can be found in reference 7 of Section 17 of 
Method 9.

                          2.0 Summary of Method

    The opacity of emissions from sources of visible emissions is 
determined visually by an observer certified according to the procedures 
in Section 10 of this method. Readings taken every 15 seconds are 
averaged over a time period specified in the applicable regulation 
ranging from 2 minutes to 6 minutes.

                       3.0 Definitions [Reserved]

                      4.0 Interferences [Reserved]

                          5.0 Safety [Reserved]

                       6.0 Equipment and Supplies

                 What equipment and supplies are needed?

    6.1 Stop Watch. Two watches are required that provide a continuous 
display of time to the nearest second.
    6.2 Compass (optional). A compass is useful for determining the 
direction of the emission point from the spot where the visible 
emissions (VE) observer stands and for determining the wind direction at 
the source. For accurate readings, the compass should be magnetic with 
resolution better than 10 degrees. It is suggested that the compass be 
jewel-mounted and liquid-filled to dampen the needle swing; map reading 
compasses are excellent.
    6.3 Range Finder (optional). Range finders determine distances from 
the observer to the emission point. The instrument should measure a 
distance of 1000 meters with a minimum accuracy of 10 percent.
    6.4 Abney Level (optional). This device for determining the vertical 
viewing angle should measure within 5 degrees.
    6.5 Sling Psychrometer (optional). In case of the formation of a 
steam plume, a wet- and dry-bulb thermometer, accurate to 0.5 [deg]C, 
are mounted on a sturdy assembly and swung rapidly in the air in order 
to determine the relative humidity.
    6.6 Binoculars (optional). Binoculars are recommended to help 
identify stacks and to characterize the plume. An 8 x 50 or 10 x 50 
magnification, color-corrected coated lenses and rectilinear field of 
view is recommended.
    6.7 Camera (optional). A camera is often used to document the 
emissions before and after the actual opacity determination.
    6.8 Safety Equipment. The following safety equipment, which should 
be approved by the Occupational Safety and Health Association (OSHA), is 
recommended: orange or yellow hard hat, eye and ear protection, and 
steel-toed safety boots.
    6.9 Clipboard and Accessories (optional). A clipboard, several ball-
point pens (black ink recommended), a rubber band, and several visible 
emission observation forms facilitate documentation.

                  7.0 Reagents and Standards (Reserved]

       8.0 Sample Collection, Preservation, Storage, and Transport

                       What is the Test Procedure?

    An observer qualified in accordance with Section 10 of this method 
must use the following procedures to visually determine the opacity of 
emissions from stationary sources.
    8.1 Procedure for Emissions from Stacks. These procedures are 
applicable for visually determining the opacity of stack emissions by a 
qualified observer.
    8.1.1 Position. You must stand at a distance sufficient to provide a 
clear view of the emissions with the sun oriented in the 140-degree 
sector to your back. Consistent with maintaining the above requirement 
as much as possible, you must make opacity observations from a position 
such that the line of vision is approximately perpendicular to the plume 
direction, and when observing opacity of emissions from rectangular 
outlets (e.g., roof monitors, open baghouses, non-circular stacks), 
approximately perpendicular to the longer axis of the outlet. You should 
not include more than one plume in the line of sight at a time when 
multiple plumes are involved and, in any case, make opacity observations 
with the line of sight perpendicular to the longer axis of such a set of 
multiple stacks (e.g., stub stacks on baghouses).
    8.1.2 Field Records. You must record the name of the plant, emission 
location, type of

[[Page 519]]

facility, observer's name and affiliation, a sketch of the observer's 
position relative to the source, and the date on a field data sheet. An 
example visible emission observation form can be found in reference 7 of 
Section 17 of this method. You must record the time, estimated distance 
to the emission location, approximate wind direction, estimated wind 
speed, description of the sky condition (presence and color of clouds), 
and plume background on the field data sheet at the time opacity 
readings are initiated and completed.
    8.1.3 Observations. You must make opacity observations at the point 
of greatest opacity in that portion of the plume where condensed water 
vapor is not present. Do not look continuously at the plume but, 
instead, observe the plume momentarily at 15-second intervals.
    8.1.3.1 Attached Steam Plumes. When condensed water vapor is present 
within the plume as it emerges from the emission outlet, you must make 
opacity observations beyond the point in the plume at which condensed 
water vapor is no longer visible. You must record the approximate 
distance from the emission outlet to the point in the plume at which the 
observations are made.
    8.1.3.2 Detached Steam Plumes. When water vapor in the plume 
condenses and becomes visible at a distinct distance from the emission 
outlet, you must make the opacity observation at the emission outlet 
prior to the condensation of water vapor and the formation of the steam 
plume.
    8.2 Recording Observations. You must record the opacity observations 
to the nearest 5 percent every 15 seconds on an observational record 
sheet such as the example visible emission observation form in reference 
7 of Section 17 of this method. Each observation recorded represents the 
average opacity of emissions for a 15-second period. The overall length 
of time for which observations are recorded must be appropriate to the 
averaging time specified in the applicable regulation.

                     9.0 Quality Control [Reserved]

                  10.0 Calibration and Standardization

    10.1 What are the Certification Requirements? To receive 
certification as a qualified observer, you must be trained and 
knowledgeable on the procedures in Section 8.0 of this method, be tested 
and demonstrate the ability to assign opacity readings in 5 percent 
increments to 25 different black plumes and 25 different white plumes, 
with an error not to exceed 15 percent opacity on any one reading and an 
average error not to exceed 7.5 percent opacity in each category. You 
must be tested according to the procedures described in Section 10.2 of 
this method. Any smoke generator used pursuant to Section 10.2 of this 
method must be equipped with a smoke meter which meets the requirements 
of Section 10.3 of this method. Certification tests that do not meet the 
requirements of Sections 10.2 and 10.3 of this method are not valid.
    The certification must be valid for a period of 6 months, and after 
each 6-month period, the qualification procedures must be repeated by an 
observer in order to retain certification.
    10.2 What is the Certification Procedure? The certification test 
consists of showing the candidate a complete run of 50 plumes, 25 black 
plumes and 25 white plumes, generated by a smoke generator. Plumes must 
be presented in random order within each set of 25 black and 25 white 
plumes. The candidate assigns an opacity value to each plume and records 
the observation on a suitable form. At the completion of each run of 50 
readings, the score of the candidate is determined. If a candidate fails 
to qualify, the complete run of 50 readings must be repeated in any 
retest. The smoke test may be administered as part of a smoke school or 
training program, and may be preceded by training or familiarization 
runs of the smoke generator during which candidates are shown black and 
white plumes of known opacity.
    10.3 Smoke Generator.
    10.3.1 What are the Smoke Generator Specifications? Any smoke 
generator used for the purpose of Section 10.2 of this method must be 
equipped with a smoke meter installed to measure opacity across the 
diameter of the smoke generator stack. The smoke meter output must 
display in-stack opacity, based upon a path length equal to the stack 
exit diameter on a full 0 to 100 percent chart recorder scale. The smoke 
meter optical design and performance must meet the specifications shown 
in Table 203A-1 of this method. The smoke meter must be calibrated as 
prescribed in Section 10.3.2 of this method prior to conducting each 
smoke reading test. At the completion of each test, the zero and span 
drift must be checked and, if the drift exceeds 1 
percent opacity, the condition must be corrected prior to conducting any 
subsequent test runs. The smoke meter must be demonstrated at the time 
of installation to meet the specifications listed in Table 203A-1 of 
this method. This demonstration must be repeated following any 
subsequent repair or replacement of the photocell or associated 
electronic circuitry including the chart recorder or output meter, or 
every 6 months, whichever occurs first.
    10.3.2 How is the Smoke Meter Calibrated? The smoke meter is 
calibrated after allowing a minimum of 30 minutes warm-up by alternately 
producing simulated opacity of 0 percent and 100 percent. When a stable 
response at 0 percent or 100 percent is noted, the smoke meter is 
adjusted to produce an output of 0 percent or 100 percent, as 
appropriate. This calibration must be repeated

[[Page 520]]

until stable 0 percent and 100 percent readings are produced without 
adjustment. Simulated 0 percent and 100 percent opacity values may be 
produced by alternately switching the power to the light source on and 
off while the smoke generator is not producing smoke.
    10.3.3 How is the Smoke Meter Evaluated? The smoke meter design and 
performance are to be evaluated as follows:
    10.3.3.1 Light Source. You must verify from manufacturer's data and 
from voltage measurements made at the lamp, as installed, that the lamp 
is operated within 5 percent of the nominal rated voltage.
    10.3.3.2 Spectral Response of the Photocell. You must verify from 
manufacturer's data that the photocell has a photopic response; i.e., 
the spectral sensitivity of the cell must closely approximate the 
standard spectral-luminosity curve for photopic vision which is 
referenced in (b) of Table 203A-1 of this method.
    10.3.3.3 Angle of View. You must check construction geometry to 
ensure that the total angle of view of the smoke plume, as seen by the 
photocell, does not exceed 15 degrees. Calculate the total angle of view 
as follows:

[phis]v = 2 tan-1 (d/2L)

Where:

[phis]v = Total angle of view
d = The photocell diameter + the diameter of the limiting aperture
L = Distance from the photocell to the limiting aperture.

The limiting aperture is the point in the path between the photocell and 
the smoke plume where the angle of view is most restricted. In smoke 
generator smoke meters, this is normally an orifice plate.
    10.3.3.4 Angle of Projection. You must check construction geometry 
to ensure that the total angle of projection of the lamp on the smoke 
plume does not exceed 15 degrees. Calculate the total angle of 
projection as follows:

[phis]p = 2 tan-1 (d/2L)

Where:

[phis]p = Total angle of projection
d = The sum of the length of the lamp filament + the diameter of the 
          limiting aperture
L = The distance from the lamp to the limiting aperture.

    10.3.3.5 Calibration Error. Using neutral-density filters of known 
opacity, you must check the error between the actual response and the 
theoretical linear response of the smoke meter. This check is 
accomplished by first calibrating the smoke meter according to Section 
10.3.2 of this method and then inserting a series of three neutral-
density filters of nominal opacity of 20, 50, and 75 percent in the 
smoke meter path length. Use filters calibrated within 2 percent. Care 
should be taken when inserting the filters to prevent stray light from 
affecting the meter. Make a total of five non-consecutive readings for 
each filter. The maximum opacity error on any one reading shall be 
3 percent.
    10.3.3.6 Zero and Span Drift. Determine the zero and span drift by 
calibrating and operating the smoke generator in a normal manner over a 
1-hour period. The drift is measured by checking the zero and span at 
the end of this period.
    10.3.3.7 Response Time. Determine the response time by producing the 
series of five simulated 0 percent and 100 percent opacity values and 
observing the time required to reach stable response. Opacity values of 
0 percent and 100 percent may be simulated by alternately switching the 
power to the light source off and on while the smoke generator is not 
operating.

                  11.0 Analytical Procedures [Reserved]

                   12.0 Data Analysis and Calculations

    12.1 Time-Averaged Regulations. A set of observations is composed of 
an appropriate number of consecutive observations determined by the 
averaging time specified (i.e., 8 observations for a two minute 
average). Divide the recorded observations into sets of appropriate time 
lengths for the specified averaging time. Sets must consist of 
consecutive observations; however, observations immediately preceding 
and following interrupted observations shall be deemed consecutive. Sets 
need not be consecutive in time and in no case shall two sets overlap. 
For each set of observations, calculate the average opacity by summing 
the opacity readings taken over the appropriate time period and dividing 
by the number of readings. For example, for a 2-minute average, eight 
consecutive readings would be averaged by adding the eight readings and 
dividing by eight.

                         13.0 Method Performance

    13.1 Time-averaging Performances. The accuracy of test procedures 
for time-averaged regulations was evaluated through field studies that 
compare the opacity readings to a transmissometer. Analysis of these 
data shows that, as the time interval for averaging increases, the 
positive error decreases. For example, over a 2-minute time period, 90 
percent of the results underestimated opacity or overestimated opacity 
by less than 9.5 percent opacity, while over a 6-minute time period, 90 
percent of the data have less than a 7.5 percent positive error. 
Overall, the field studies demonstrated a negative bias. Over a 2-minute 
time period, 57 percent of the data have zero or negative error, and 
over a 6-minute time period, 58 percent of the data have zero or 
negative error. This means that observers are more likely to assign 
opacity

[[Page 521]]

values that are below, rather than above, the actual opacity value. 
Consequently, a larger percentage of noncompliance periods will be 
reported as compliant periods rather than compliant periods reported as 
violations. Table 203A-2 highlights the precision data results from the 
June 1985 report: ``Opacity Errors for Averaging and Non Averaging Data 
Reduction and Reporting Techniques.''

                  14.0 Pollution Prevention [Reserved]

                    15.0 Waste Management [Reserved]

                 16.0 Alternative Procedures [Reserved]

                             17.0 References

    1. U.S. Environmental Protection Agency. Standards of Performance 
for New Stationary Sources; Appendix A; Method 9 for Visual 
Determination of the Opacity of Emissions from Stationary Sources. Final 
Rule. 39 FR 219. Washington, DC. U.S. Government Printing Office. 
November 12, 1974.
    2. Office of Air and Radiation. ``Quality Assurance Guideline for 
Visible Emission Training Programs.'' EPA-600/S4-83-011. Quality 
Assurance Division. Research Triangle Park, NC. May 1982.
    3. Office of Research and Development. ``Method 9--Visible 
Determination of the Opacity of Emissions from Stationary Sources.'' 
February 1984. Quality Assurance Handbook for Air Pollution Measurement 
Systems. Volume III, Section 3.1.2. Stationary Source Specific Methods. 
EPA-600-4-77-027b. August 1977. Office of Research and Development 
Publications, 26 West Clair Street, Cincinnati, OH.
    4. Office of Air Quality Planning and Standards. ``Opacity Error for 
Averaging and Non-averaging Data Reduction and Reporting Techniques.'' 
Final Report-SR-1-6-85. Emission Measurement Branch, Research Triangle 
Park, NC. June 1985.
    5. U.S. Environmental Protection Agency. Preparation, Adoption, and 
Submittal of State Implementation Plans. Methods for Measurement of 
PM10 Emissions from Stationary Sources. Final Rule. Federal 
Register. Washington, DC. U.S. Government Printing Office. Volume 55, 
No. 74. Pages 14246-14279. April 17, 1990.
    6. Office of Air Quality Planning and Standards. ``Collaborative 
Study of Opacity Observations of Fugitive Emissions from Unpaved Roads 
by Certified Observers.'' Emission Measurement Branch, Research Triangle 
Park, NC. October 1986.
    7. Office of Air Quality Planning and Standards. ``Field Data Forms 
and Instructions for EPA Methods 203A, 203B, and 203C.'' EPA 455/R-93-
005. Stationary Source Compliance Division, Washington, DC, June 1993.

         18.0 Tables, Diagrams, Flowcharts, and Validation Data

     Table 203A-1--Smoke Meter Design and Performance Specifications
------------------------------------------------------------------------
               Parameter                          Specification
------------------------------------------------------------------------
a. Light Source........................  Incandescent lamp operated at
                                          nominal rated voltage.
b. Spectral response of photocell......  Photopic (daylight spectral
                                          response of the human eye--
                                          Citation 3).
c. Angle of view.......................  15[deg] maximum total angle.
d. Angle of projection.................  15[deg] maximum total angle.
e. Calibration error...................  3%
                                          opacity, maximum.
f. Zero and span drift.................  1%
                                          opacity, 30 minutes
g. Response time.......................  5 seconds.
------------------------------------------------------------------------


                          Table 203A-2--Precision Between Observers: Opacity Averaging
----------------------------------------------------------------------------------------------------------------
                                                                                     Standard       Amount with
                        Averaging period                             Number of     deviation (%    <7.5% opacity
                                                                   observations      opacity)       difference
----------------------------------------------------------------------------------------------------------------
15-second.......................................................         140,250             3.4              87
2 minutes.......................................................          17,694             2.6              92
3 minutes.......................................................          11,836             2.4              92
6 minutes.......................................................           5,954             2.1              93
----------------------------------------------------------------------------------------------------------------


[[Page 522]]

     Method 203B--Visual Determination of Opacity of Emissions From 
            Stationary Sources for Time-Exception Regulations

                        1.0 Scope and Application

                          What is Method 203B?

    Method 203B is an example test method suitable for State 
Implementation Plans (SIPs) and is applicable to the determination of 
the opacity of emissions from sources of visible emissions for time-
exception regulations. A time-exception regulation means any regulation 
that allows predefined periods of opacity above the otherwise applicable 
opacity limit (e.g., allowing exceedances of 20 percent opacity for 3 
minutes in 1 hour.)
    Method 203B is virtually identical to EPA's Method 9 of 40 CFR part 
60, Appendix A, except for the data-reduction procedures, which have 
been modified to apply to time-exception regulations. The certification 
procedures for this method are identical to those provided in Method 9. 
An example of a visible emission observation form and instructions for 
its use can be found in reference 7 of Section 17 of Method 203A.

                          2.0 Summary of Method

    The opacity of emissions from sources of visible emissions is 
determined visually by a qualified observer.

                       3.0 Definitions [Reserved]

                      4.0 Interferences [Reserved]

                          5.0 Safety [Reserved]

                       6.0 Equipment and Supplies

                 What equipment and supplies are needed?

    The same as specified in Section 6.0 of Method 203A.

                  7.0 Reagents and Standards [Reserved]

       8.0 Sample Collection, Preservation, Storage, and Transport

                       What is the Test Procedure?

    The observer qualified in accordance with Section 10 of Method 203A 
must use the following procedures for visually determining the opacity 
of emissions.
    8.1 Procedures for Emissions From Stationary Sources. The procedures 
for emissions from stationary sources are the same as specified in 8.1 
of Method 203A.
    8.2 Recording Observations. You must record opacity observations to 
the nearest 5 percent at 15-second intervals on an observational record 
sheet. Each observation recorded represents the average opacity of 
emissions for a 15-second period. The overall length of time for which 
observations are recorded must be appropriate to the applicable 
regulation.

                     9.0 Quality Control [Reserved]

                  10.0 Calibration and Standardization

    The Calibration and Standardization requirements are the same as 
specified in Section 10 of Method 203A.

                  11.0 Analytical Procedures [Reserved]

                   12.0 Data Analysis and Calculations

    Data Reduction for Time-Exception Regulations. For a time-exception 
regulation, reduce opacity observations as follows: Count the number of 
observations above the applicable standard and multiply that number by 
0.25 to determine the minutes of emissions above the target opacity.

                         13.0 Method Performance

    13.1 Time-Exception Regulations. ``Opacity Errors for Averaging and 
Non-Averaging Data Reduction and Reporting Techniques'' analyzed the 
time errors associated with false compliance or false non-compliance 
determinations resulting from a sample of 1110 opacity readings with 6-
minute observation periods. The study applied a 20 percent opacity 
standard. Fifty-one percent of the data showed zero error in time 
determinations. The standard deviation was 97.5 seconds for the 6-minute 
time period.
    13.1.1 Overall, the study showed a negative bias. Each reading is 
associated with a 15-second block of time. The readings were multiplied 
by 15 seconds and the resulting time spent above the standard was 
compared to the transmissometer results. The average amount of time that 
observations deviated from the transmissometer's determinations was -8.3 
seconds. Seventy percent of the time determinations were either correct 
or underestimated the time of excess emissions. Consequently, a larger 
percentage of noncompliance periods would be reported as compliant 
periods rather than compliant periods reported as violations.
    13.1.2 Some time-exception regulations reduce the data by averaging 
over 1-minute periods and then counting those minutes above the 
standard. This data reduction procedure results in a less stringent 
standard than determinations resulting from data reduction procedures of 
Method 203B.

                  14.0 Pollution Prevention [Reserved]

                    15.0 Waste Management [Reserved]

                 16.0 Alternative Procedures [Reserved]

                             17.0 References

    The references are the same as specified in Section 17 of Method 
203A.

[[Page 523]]

    18.0 Tables, Diagrams, Flowcharts, and Validation Data [Reserved]

     Method 203C--Visual Determination of Opacity of Emissions From 
       Stationary Sources for Instantaneous Limitation Regulations

                        1.0 Scope and Application

                          What is Method 203C?

    Method 203C is an example test method suitable for State 
Implementation Plans (SIPs) and is applicable to the determination of 
the opacity of emissions from sources of visible emissions for 
regulations with an instantaneous opacity limitation. An instantaneous 
opacity limitation is an opacity limit which is never to be exceeded.
    Method 203C is virtually identical to EPA's Method 9 of 40 CFR Part 
60, Appendix A, except for 5-second reading intervals and the data-
reduction procedures, which have been modified for instantaneous 
limitation regulations. The certification procedures for this method are 
virtually identical to Method 9. An example visible emission observation 
form and instructions for its use can be found in reference 7 of Section 
17 of Method 203A.

                          2.0 Summary of Method

    The opacity of emissions from sources of visible emissions is 
determined visually by an observer certified according to the procedures 
in Section 10 of Method 203A.

                       3.0 Definitions [Reserved]

                      4.0 Interferences [Reserved]

                          5.0 Safety [Reserved]

                       6.0 Equipment and Supplies

    The equipment and supplies used are the same as Section 6.0 of 
Method 203A.

                  7.0 Reagents and Standards [Reserved]

       8.0 Sample Collection, Preservation, Storage, and Transport

                       What is the Test Procedure?

    The qualified observer must use the following procedures for 
visually determining the opacity of emissions.
    8.1 Procedures for Emissions From Stationary Sources. These are the 
same as Section 8.1 of Method 203A.
    8.1.1 Position. Same as Section 8.1.1 of Method 203A.
    8.1.2 Field Records. Same as Section 8.1.2 of Method 203A.
    8.1.3 Observations. Make opacity observations at the point of 
greatest opacity in that portion of the plume where condensed water 
vapor is not present. Do not look continuously at the plume, instead, 
observe the plume momentarily at 5-second intervals.
    8.1.3.1 Attached Steam Plumes. Same as Section 8.1.3.1 of Method 
203A.
    8.1.3.2 Detached Steam Plumes. Same as Section 8.1.3.2 of Method 
203A.
    8.2 Recording Observations. You must record opacity observations to 
the nearest 5 percent at 5-second intervals on an observational record 
sheet. Each observation recorded represents the average of emissions for 
the 5-second period. The overall time for which recordings are made must 
be of a length appropriate to the applicable regulation for which 
opacity is being measured.

                     9.0 Quality Control [Reserved]

                  10.0 Calibration and Standardization

    The calibration and standardization procedures are the same as 
Section 10 of Method 203A.

                  11.0 Analytical Procedures [Reserved]

                   12.0 Data Analysis and Calculations

    12.1 Data Reduction for Instantaneous Limitation Regulations. For an 
instantaneous limitation regulation, a 1-minute averaging time will be 
used. You must divide the observations recorded on the record sheet into 
sets of consecutive observations. A set is composed of the consecutive 
observations made in 1 minute. Sets need not be consecutive in time, and 
in no case must two sets overlap. You must reduce opacity observations 
by dividing the sum of all observations recorded in a set by the number 
of observations recorded in each set.
    12.2 Reduce opacity observations by averaging 12 consecutive 
observations recorded at 5-second intervals. Divide the observations 
recorded on the record sheet into sets of 12 consecutive observations. 
For each set of 12 observations, calculate the average by summing the 
opacity of the 12 observations and dividing this sum by 12.

                         13.0 Method Performance

    The results of the ``Collaborative Study of Opacity Observations at 
Five-second Intervals by Certified Observers'' are almost identical to 
those of previous studies of Method 9 observations taken at 15-second 
intervals and indicate that observers can make valid observations at 5-
second intervals. The average difference of all observations from the 
transmissometer values was 8.8 percent opacity, which shows a fairly 
high negative bias. Underestimating the opacity of the visible emissions 
is more likely than overestimating the opacity of the emissions.

[[Page 524]]

                  14.0 Pollution Prevention [Reserved]

                    15.0 Waste Management [Reserved]

                 16.0 Alternative Procedures [Reserved]

                             17.0 References

    The references are the same as references 1-7 in Method 203A in 
addition to the following:
    1. Office of Air Quality Planning and Standards. ``Collaborative 
Study of Opacity Observations at Five-second Intervals by Certified 
Observers.'' Docket A-84-22, IV-A-2. Emission Measurement Branch, 
Research Triangle Park, N.C. September 1990.

         18.0 Tables, Diagrams, Flowcharts, and Validation Data

 Method 204--Criteria for and Verification of a Permanent or Temporary 
                             Total Enclosure

                        1. Scope and Application

    This procedure is used to determine whether a permanent or temporary 
enclosure meets the criteria for a total enclosure. An existing building 
may be used as a temporary or permanent enclosure as long as it meets 
the appropriate criteria described in this method.

                          2. Summary of Method

    An enclosure is evaluated against a set of criteria. If the criteria 
are met and if all the exhaust gases from the enclosure are ducted to a 
control device, then the volatile organic compounds (VOC) capture 
efficiency (CE) is assumed to be 100 percent, and CE need not be 
measured. However, if part of the exhaust gas stream is not ducted to a 
control device, CE must be determined.

                             3. Definitions

    3.1 Natural Draft Opening (NDO). Any permanent opening in the 
enclosure that remains open during operation of the facility and is not 
connected to a duct in which a fan is installed.
    3.2 Permanent Total Enclosure (PE). A permanently installed 
enclosure that completely surrounds a source of emissions such that all 
VOC emissions are captured and contained for discharge to a control 
device.
    3.3 Temporary Total Enclosure (TTE). A temporarily installed 
enclosure that completely surrounds a source of emissions such that all 
VOC emissions that are not directed through the control device (i.e., 
uncaptured) are captured by the enclosure and contained for discharge 
through ducts that allow for the accurate measurement of the uncaptured 
VOC emissions.
    3.4 Building Enclosure (BE). An existing building that is used as a 
TTE.

                                4. Safety

    An evaluation of the proposed building materials and the design for 
the enclosure is recommended to minimize any potential hazards.

                5. Criteria for Temporary Total Enclosure

    5.1 Any NDO shall be at least four equivalent opening diameters from 
each VOC emitting point unless otherwise specified by the Administrator.
    5.2 Any exhaust point from the enclosure shall be at least four 
equivalent duct or hood diameters from each NDO.
    5.3 The total area of all NDO's shall not exceed 5 percent of the 
surface area of the enclosure's four walls, floor, and ceiling.
    5.4 The average facial velocity (FV) of air through all NDO's shall 
be at least 3,600 m/hr (200 fpm). The direction of air flow through all 
NDO's shall be into the enclosure.
    5.5 All access doors and windows whose areas are not included in 
section 5.3 and are not included in the calculation in section 5.4 shall 
be closed during routine operation of the process.

               6. Criteria for a Permanent Total Enclosure

    6.1 Same as sections 5.1 and 5.3 through 5.5.
    6.2 All VOC emissions must be captured and contained for discharge 
through a control device.

                           7. Quality Control

    7.1 The success of this method lies in designing the TTE to simulate 
the conditions that exist without the TTE (i.e., the effect of the TTE 
on the normal flow patterns around the affected facility or the amount 
of uncaptured VOC emissions should be minimal). The TTE must enclose the 
application stations, coating reservoirs, and all areas from the 
application station to the oven. The oven does not have to be enclosed 
if it is under negative pressure. The NDO's of the temporary enclosure 
and an exhaust fan must be properly sized and placed.
    7.2 Estimate the ventilation rate of the TTE that best simulates the 
conditions that exist without the TTE (i.e., the effect of the TTE on 
the normal flow patterns around the affected facility or the amount of 
uncaptured VOC emissions should be minimal). Figure 204-1 or the 
following equation may be used as an aid.
[GRAPHIC] [TIFF OMITTED] TR16JN97.000

Measure the concentration (CG) and flow rate (QG) 
of the captured gas stream, specify a safe concentration (CF) 
for the uncaptured gas stream, estimate the CE, and then use the plot in 
Figure 204-1 or Equation 204-1 to

[[Page 525]]

determine the volumetric flow rate of the uncaptured gas stream (QF). An 
exhaust fan that has a variable flow control is desirable.
    7.3 Monitor the VOC concentration of the captured gas steam in the 
duct before the capture device without the TTE. To minimize the effect 
of temporal variation on the captured emissions, the baseline 
measurement should be made over as long a time period as practical. 
However, the process conditions must be the same for the measurement in 
section 7.5 as they are for this baseline measurement. This may require 
short measuring times for this quality control check before and after 
the construction of the TTE.
    7.4 After the TTE is constructed, monitor the VOC concentration 
inside the TTE. This concentration should not continue to increase, and 
must not exceed the safe level according to Occupational Safety and 
Health Administration requirements for permissible exposure limits. An 
increase in VOC concentration indicates poor TTE design.
    7.5 Monitor the VOC concentration of the captured gas stream in the 
duct before the capture device with the TTE. To limit the effect of the 
TTE on the process, the VOC concentration with and without the TTE must 
be within 10 percent. If the measurements do not agree, adjust the 
ventilation rate from the TTE until they agree within 10 percent.

                              8. Procedure

    8.1 Determine the equivalent diameters of the NDO's and determine 
the distances from each VOC emitting point to all NDO's. Determine the 
equivalent diameter of each exhaust duct or hood and its distance to all 
NDO's. Calculate the distances in terms of equivalent diameters. The 
number of equivalent diameters shall be at least four.
    8.2 Measure the total surface area (AT) of the enclosure 
and the total area (AN) of all NDO's in the enclosure. 
Calculate the NDO to enclosure area ratio (NEAR) as follows:
[GRAPHIC] [TIFF OMITTED] TR16JN97.001

The NEAR must be <=0.05.
    8.3 Measure the volumetric flow rate, corrected to standard 
conditions, of each gas stream exiting the enclosure through an exhaust 
duct or hood using EPA Method 2. In some cases (e.g., when the building 
is the enclosure), it may be necessary to measure the volumetric flow 
rate, corrected to standard conditions, of each gas stream entering the 
enclosure through a forced makeup air duct using Method 2. Calculate FV 
using the following equation:
[GRAPHIC] [TIFF OMITTED] TR16JN97.002

where:

QO = the sum of the volumetric flow from all gas streams 
          exiting the enclosure through an exhaust duct or hood.
QI = the sum of the volumetric flow from all gas streams into 
          the enclosure through a forced makeup air duct; zero, if there 
          is no forced makeup air into the enclosure.
AN = total area of all NDO's in enclosure.

    The FV shall be at least 3,600 m/hr (200 fpm). Alternatively, 
measure the pressure differential across the enclosure. A pressure drop 
of 0.013 mm Hg (0.007 in. H2O) corresponds to an FV of 3,600 
m/hr (200 fpm).
    8.4 Verify that the direction of air flow through all NDO's is 
inward. If FV is less than 9,000 m/hr (500 fpm), the continuous inward 
flow of air shall be verified using streamers, smoke tubes, or tracer 
gases. Monitor the direction of air flow for at least 1 hour, with 
checks made no more than 10 minutes apart. If FV is greater than 9,000 
m/hr (500 fpm), the direction of air flow through the NDOs shall be 
presumed to be inward at all times without verification.

                               9. Diagrams

[[Page 526]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.026

 Method 204A--Volatile Organic Compounds Content in Liquid Input Stream

                        1. Scope and Application

    1.1 Applicability. This procedure is applicable for determining the 
input of volatile organic compounds (VOC). It is intended to be used in 
the development of liquid/gas protocols for determining VOC capture 
efficiency (CE) for surface coating and printing operations.
    1.2 Principle. The amount of VOC introduced to the process (L) is 
the sum of the products of the weight (W) of each VOC containing liquid 
(ink, paint, solvent, etc.) used and its VOC content (V).

[[Page 527]]

    1.3 Sampling Requirements. A CE test shall consist of at least three 
sampling runs. Each run shall cover at least one complete production 
cycle, but shall be at least 3 hours long. The sampling time for each 
run need not exceed 8 hours, even if the production cycle has not been 
completed. Alternative sampling times may be used with the approval of 
the Administrator.

                          2. Summary of Method

    The amount of VOC containing liquid introduced to the process is 
determined as the weight difference of the feed material before and 
after each sampling run. The VOC content of the liquid input material is 
determined by volatilizing a small aliquot of the material and analyzing 
the volatile material using a flame ionization analyzer (FIA). A sample 
of each VOC containing liquid is analyzed with an FIA to determine V.

                                3. Safety

    Because this procedure is often applied in highly explosive areas, 
caution and care should be exercised in choosing, installing, and using 
the appropriate equipment.

                        4. Equipment and Supplies

    Mention of trade names or company products does not constitute 
endorsement. All gas concentrations (percent, ppm) are by volume, unless 
otherwise noted.
    4.1 Liquid Weight.
    4.1.1 Balances/Digital Scales. To weigh drums of VOC containing 
liquids to within 0.2 lb or 1.0 percent of the total weight of VOC 
liquid used.
    4.1.2 Volume Measurement Apparatus (Alternative). Volume meters, 
flow meters, density measurement equipment, etc., as needed to achieve 
the same accuracy as direct weight measurements.
    4.2 VOC Content (FIA Technique). The liquid sample analysis system 
is shown in Figures 204A-1 and 204A-2. The following equipment is 
required:
    4.2.1 Sample Collection Can. An appropriately-sized metal can to be 
used to collect VOC containing materials. The can must be constructed in 
such a way that it can be grounded to the coating container.
    4.2.2 Needle Valves. To control gas flow.
    4.2.3 Regulators. For carrier gas and calibration gas cylinders.
    4.2.4 Tubing. Teflon or stainless steel tubing with diameters and 
lengths determined by connection requirements of equipment. The tubing 
between the sample oven outlet and the FIA shall be heated to maintain a 
temperature of 120 5 [deg]C.
    4.2.5 Atmospheric Vent. A tee and 0- to 0.5-liter/min rotameter 
placed in the sampling line between the carrier gas cylinder and the VOC 
sample vessel to release the excess carrier gas. A toggle valve placed 
between the tee and the rotameter facilitates leak tests of the analysis 
system.
    4.2.6 Thermometer. Capable of measuring the temperature of the hot 
water bath to within 1 [deg]C.
    4.2.7 Sample Oven. Heated enclosure, containing calibration gas coil 
heaters, critical orifice, aspirator, and other liquid sample analysis 
components, capable of maintaining a temperature of 120 5 [deg]C.
    4.2.8 Gas Coil Heaters. Sufficient lengths of stainless steel or 
Teflon tubing to allow zero and calibration gases to be heated to the 
sample oven temperature before entering the critical orifice or 
aspirator.
    4.2.9 Water Bath. Capable of heating and maintaining a sample vessel 
temperature of 100 5 [deg]C.
    4.2.10 Analytical Balance. To measure 0.001 g.
    4.2.11 Disposable Syringes. 2-cc or 5-cc.
    4.2.12 Sample Vessel. Glass, 40-ml septum vial. A separate vessel is 
needed for each sample.
    4.2.13 Rubber Stopper. Two-hole stopper to accommodate 3.2-mm (\1/
8\-in.) Teflon tubing, appropriately sized to fit the opening of the 
sample vessel. The rubber stopper should be wrapped in Teflon tape to 
provide a tighter seal and to prevent any reaction of the sample with 
the rubber stopper. Alternatively, any leak-free closure fabricated of 
nonreactive materials and accommodating the necessary tubing fittings 
may be used.
    4.2.14 Critical Orifices. Calibrated critical orifices capable of 
providing constant flow rates from 50 to 250 ml/min at known pressure 
drops. Sapphire orifice assemblies (available from O'Keefe Controls 
Company) and glass capillary tubing have been found to be adequate for 
this application.
    4.2.15 Vacuum Gauge. Zero to 760-mm (0- to 30-in.) Hg U-Tube 
manometer or vacuum gauge.
    4.2.16 Pressure Gauge. Bourdon gauge capable of measuring the 
maximum air pressure at the aspirator inlet (e.g., 100 psig).
    4.2.17 Aspirator. A device capable of generating sufficient vacuum 
at the sample vessel to create critical flow through the calibrated 
orifice when sufficient air pressure is present at the aspirator inlet. 
The aspirator must also provide sufficient sample pressure to operate 
the FIA. The sample is also mixed with the dilution gas within the 
aspirator.
    4.2.18 Soap Bubble Meter. Of an appropriate size to calibrate the 
critical orifices in the system.
    4.2.19 Organic Concentration Analyzer. An FIA with a span value of 
1.5 times the expected concentration as propane; however, other span 
values may be used if it can be demonstrated that they would provide 
more accurate measurements. The FIA instrument should be the same 
instrument used in the gaseous analyses adjusted with the same

[[Page 528]]

fuel, combustion air, and sample back-pressure (flow rate) settings. The 
system shall be capable of meeting or exceeding the following 
specifications:
    4.2.19.1 Zero Drift. Less than 3.0 percent of 
the span value.
    4.2.19.2 Calibration Drift. Less than 3.0 
percent of the span value.
    4.2.19.3 Calibration Error. Less than 5.0 
percent of the calibration gas value.
    4.2.20 Integrator/Data Acquisition System. An analog or digital 
device or computerized data acquisition system used to integrate the FIA 
response or compute the average response and record measurement data. 
The minimum data sampling frequency for computing average or integrated 
values is one measurement value every 5 seconds. The device shall be 
capable of recording average values at least once per minute.
    4.2.21 Chart Recorder (Optional). A chart recorder or similar device 
is recommended to provide a continuous analog display of the measurement 
results during the liquid sample analysis.

                        5. Reagents and Standards

    5.1 Calibration and Other Gases. Gases used for calibration, fuel, 
and combustion air (if required) are contained in compressed gas 
cylinders. All calibration gases shall be traceable to National 
Institute of Standards and Technology standards and shall be certified 
by the manufacturer to 1 percent of the tag value. 
Additionally, the manufacturer of the cylinder should provide a 
recommended shelf life for each calibration gas cylinder over which the 
concentration does not change more than 2 percent 
from the certified value. For calibration gas values not generally 
available, dilution systems calibrated using Method 205 may be used. 
Alternative methods for preparing calibration gas mixtures may be used 
with the approval of the Administrator.
    5.1.1 Fuel. The FIA manufacturer's recommended fuel should be used. 
A 40 percent H2/60 percent He or 40 percent H2/60 percent 
N2 gas mixture is recommended to avoid an oxygen synergism 
effect that reportedly occurs when oxygen concentration varies 
significantly from a mean value. Other mixtures may be used provided the 
tester can demonstrate to the Administrator that there is no oxygen 
synergism effect.
    5.1.2 Carrier Gas. High purity air with less than 1 ppm of organic 
material (as propane) or less than 0.1 percent of the span value, 
whichever is greater.
    5.1.3 FIA Linearity Calibration Gases. Low-, mid-, and high-range 
gas mixture standards with nominal propane concentrations of 20-30, 45-
55, and 70-80 percent of the span value in air, respectively. Other 
calibration values and other span values may be used if it can be shown 
to the Administrator's satisfaction that equally accurate measurements 
would be achieved.
    5.1.4 System Calibration Gas. Gas mixture standard containing 
propane in air, approximating the undiluted VOC concentration expected 
for the liquid samples.

             6. Sample Collection, Preservation and Storage

    6.1 Samples must be collected in a manner that prevents or minimizes 
loss of volatile components and that does not contaminate the coating 
reservoir.
    6.2 Collect a 100-ml or larger sample of the VOC containing liquid 
mixture at each application location at the beginning and end of each 
test run. A separate sample should be taken of each VOC containing 
liquid added to the application mixture during the test run. If a fresh 
drum is needed during the sampling run, then obtain a sample from the 
fresh drum.
    6.3 When collecting the sample, ground the sample container to the 
coating drum. Fill the sample container as close to the rim as possible 
to minimize the amount of headspace.
    6.4 After the sample is collected, seal the container so the sample 
cannot leak out or evaporate.
    6.5 Label the container to clearly identify the contents.

                           7. Quality Control

    7.1 Required instrument quality control parameters are found in the 
following sections:
    7.1.1 The FIA system must be calibrated as specified in section 8.1.
    7.1.2 The system drift check must be performed as specified in 
section 8.2.

                   8. Calibration and Standardization

    8.1 FIA Calibration and Linearity Check. Make necessary adjustments 
to the air and fuel supplies for the FIA and ignite the burner. Allow 
the FIA to warm up for the period recommended by the manufacturer. 
Inject a calibration gas into the measurement system and adjust the 
back-pressure regulator to the value required to achieve the flow rates 
specified by the manufacturer. Inject the zero- and the high-range 
calibration gases and adjust the analyzer calibration to provide the 
proper responses. Inject the low- and mid-range gases and record the 
responses of the measurement system. The calibration and linearity of 
the system are acceptable if the responses for all four gases are within 
5 percent of the respective gas values. If the performance of the system 
is not acceptable, repair or adjust the system and repeat the linearity 
check. Conduct a calibration and linearity check after assembling the 
analysis system and after a major change is made to the system.

[[Page 529]]

    8.2 Systems Drift Checks. After each sample, repeat the system 
calibration checks in section 9.2.7 before any adjustments to the FIA or 
measurement system are made. If the zero or calibration drift exceeds 
3 percent of the span value, discard the result 
and repeat the analysis.
    Alternatively, recalibrate the FIA as in section 8.1 and report the 
results using both sets of calibration data (i.e., data determined prior 
to the test period and data determined following the test period). The 
data that results in the lowest CE value shall be reported as the 
results for the test run.
    8.3 Critical Orifice Calibration.
    8.3.1 Each critical orifice must be calibrated at the specific 
operating conditions under which it will be used. Therefore, assemble 
all components of the liquid sample analysis system as shown in Figure 
204A-3. A stopwatch is also required.
    8.3.2 Turn on the sample oven, sample line, and water bath heaters, 
and allow the system to reach the proper operating temperature. Adjust 
the aspirator to a vacuum of 380 mm (15 in.) Hg vacuum. Measure the time 
required for one soap bubble to move a known distance and record 
barometric pressure.
    8.3.3 Repeat the calibration procedure at a vacuum of 406 mm (16 
in.) Hg and at 25-mm (1-in.) Hg intervals until three consecutive 
determinations provide the same flow rate. Calculate the critical flow 
rate for the orifice in ml/min at standard conditions. Record the vacuum 
necessary to achieve critical flow.

                              9. Procedure

    9.1 Determination of Liquid Input Weight.
    9.1.1 Weight Difference. Determine the amount of material introduced 
to the process as the weight difference of the feed material before and 
after each sampling run. In determining the total VOC containing liquid 
usage, account for:
    (a) The initial (beginning) VOC containing liquid mixture.
    (b) Any solvent added during the test run.
    (c) Any coating added during the test run.
    (d) Any residual VOC containing liquid mixture remaining at the end 
of the sample run.
    9.1.1.1 Identify all points where VOC containing liquids are 
introduced to the process. To obtain an accurate measurement of VOC 
containing liquids, start with an empty fountain (if applicable). After 
completing the run, drain the liquid in the fountain back into the 
liquid drum (if possible) and weigh the drum again. Weigh the VOC 
containing liquids to 0.5 percent of the total 
weight (full) or 1.0 percent of the total weight 
of VOC containing liquid used during the sample run, whichever is less. 
If the residual liquid cannot be returned to the drum, drain the 
fountain into a preweighed empty drum to determine the final weight of 
the liquid.
    9.1.1.2 If it is not possible to measure a single representative 
mixture, then weigh the various components separately (e.g., if solvent 
is added during the sampling run, weigh the solvent before it is added 
to the mixture). If a fresh drum of VOC containing liquid is needed 
during the run, then weigh both the empty drum and fresh drum.
    9.1.2 Volume Measurement (Alternative). If direct weight 
measurements are not feasible, the tester may use volume meters or flow 
rate meters and density measurements to determine the weight of liquids 
used if it can be demonstrated that the technique produces results 
equivalent to the direct weight measurements. If a single representative 
mixture cannot be measured, measure the components separately.
    9.2 Determination of VOC Content in Input Liquids
    9.2.1 Assemble the liquid VOC content analysis system as shown in 
Figure 204A-1.
    9.2.2 Permanently identify all of the critical orifices that may be 
used. Calibrate each critical orifice under the expected operating 
conditions (i.e., sample vacuum and temperature) against a volume meter 
as described in section 8.3.
    9.2.3 Label and tare the sample vessels (including the stoppers and 
caps) and the syringes.
    9.2.4 Install an empty sample vessel and perform a leak test of the 
system. Close the carrier gas valve and atmospheric vent and evacuate 
the sample vessel to 250 mm (10 in.) Hg absolute or less using the 
aspirator. Close the toggle valve at the inlet to the aspirator and 
observe the vacuum for at least 1 minute. If there is any change in the 
sample pressure, release the vacuum, adjust or repair the apparatus as 
necessary, and repeat the leak test.
    9.2.5 Perform the analyzer calibration and linearity checks 
according to the procedure in section 5.1. Record the responses to each 
of the calibration gases and the back-pressure setting of the FIA.
    9.2.6 Establish the appropriate dilution ratio by adjusting the 
aspirator air supply or substituting critical orifices. Operate the 
aspirator at a vacuum of at least 25 mm (1 in.) Hg greater than the 
vacuum necessary to achieve critical flow. Select the dilution ratio so 
that the maximum response of the FIA to the sample does not exceed the 
high-range calibration gas.
    9.2.7 Perform system calibration checks at two levels by introducing 
compressed gases at the inlet to the sample vessel while the aspirator 
and dilution devices are operating. Perform these checks using the 
carrier gas (zero concentration) and the system calibration gas. If the 
response to the carrier

[[Page 530]]

gas exceeds 0.5 percent of span, clean or repair 
the apparatus and repeat the check. Adjust the dilution ratio as 
necessary to achieve the correct response to the upscale check, but do 
not adjust the analyzer calibration. Record the identification of the 
orifice, aspirator air supply pressure, FIA back-pressure, and the 
responses of the FIA to the carrier and system calibration gases.
    9.2.8 After completing the above checks, inject the system 
calibration gas for approximately 10 minutes. Time the exact duration of 
the gas injection using a stopwatch. Determine the area under the FIA 
response curve and calculate the system response factor based on the 
sample gas flow rate, gas concentration, and the duration of the 
injection as compared to the integrated response using Equations 204A-2 
and 204A-3.
    9.2.9 Verify that the sample oven and sample line temperatures are 
120 5 [deg]C and that the water bath temperature 
is 100 5 [deg]C.
    9.2.10 Fill a tared syringe with approximately 1 g of the VOC 
containing liquid and weigh it. Transfer the liquid to a tared sample 
vessel. Plug the sample vessel to minimize sample loss. Weigh the sample 
vessel containing the liquid to determine the amount of sample actually 
received. Also, as a quality control check, weigh the empty syringe to 
determine the amount of material delivered. The two coating sample 
weights should agree within 0.02 g. If not, repeat the procedure until 
an acceptable sample is obtained.
    9.2.11 Connect the vessel to the analysis system. Adjust the 
aspirator supply pressure to the correct value. Open the valve on the 
carrier gas supply to the sample vessel and adjust it to provide a 
slight excess flow to the atmospheric vent. As soon as the initial 
response of the FIA begins to decrease, immerse the sample vessel in the 
water bath. (Applying heat to the sample vessel too soon may cause the 
FIA response to exceed the calibrated range of the instrument and, thus, 
invalidate the analysis.)
    9.2.12 Continuously measure and record the response of the FIA until 
all of the volatile material has been evaporated from the sample and the 
instrument response has returned to the baseline (i.e., response less 
than 0.5 percent of the span value). Observe the aspirator supply 
pressure, FIA back-pressure, atmospheric vent, and other system 
operating parameters during the run; repeat the analysis procedure if 
any of these parameters deviate from the values established during the 
system calibration checks in section 9.2.7. After each sample, perform 
the drift check described in section 8.2. If the drift check results are 
acceptable, calculate the VOC content of the sample using the equations 
in section 11.2. Alternatively, recalibrate the FIA as in section 8.1 
and report the results using both sets of calibration data (i.e., data 
determined prior to the test period and data determined following the 
test period). The data that results in the lowest CE value shall be 
reported as the results for the test run. Integrate the area under the 
FIA response curve, or determine the average concentration response and 
the duration of sample analysis.

                   10. Data Analysis and Calculations

    10.1 Nomenclature.
AL = area under the response curve of the liquid sample, area 
          count.
AS = area under the response curve of the calibration gas, 
          area count.
CS = actual concentration of system calibration gas, ppm 
          propane.
K = 1.830 x 10-9 g/(ml-ppm).
L = total VOC content of liquid input, kg.
ML = mass of liquid sample delivered to the sample vessel, g.
q = flow rate through critical orifice, ml/min.
RF = liquid analysis system response factor, g/area count.
[thetas]S = total gas injection time for system calibration 
          gas during integrator calibration, min.
VFj = final VOC fraction of VOC containing liquid j.
VIj = initial VOC fraction of VOC containing liquid j.
VAj = VOC fraction of VOC containing liquid j added during 
          the run.
V = VOC fraction of liquid sample.
WFj = weight of VOC containing liquid j remaining at end of 
          the run, kg.
WIj = weight of VOC containing liquid j at beginning of the 
          run, kg.
WAj = weight of VOC containing liquid j added during the run, 
          kg.
    10.2 Calculations
    10.2.1 Total VOC Content of the Input VOC Containing Liquid.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.003
    

[[Page 531]]


    10.2.2 Liquid Sample Analysis System Response Factor for Systems 
Using Integrators, Grams/Area Count.
[GRAPHIC] [TIFF OMITTED] TR16JN97.004

    10.2.3 VOC Content of the Liquid Sample.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.005
    
                         11. Method Performance

    The measurement uncertainties are estimated for each VOC containing 
liquid as follows: W = 2.0 percent and V = 4.0 percent. Based on these numbers, the probable 
uncertainty for L is estimated at about 4.5 
percent for each VOC containing liquid.

                              12. Diagrams

[[Page 532]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.036


[[Page 533]]


[GRAPHIC] [TIFF OMITTED] TR16JN97.037


[[Page 534]]


[GRAPHIC] [TIFF OMITTED] TR16JN97.038


[[Page 535]]



  Method 204B--Volatile Organic Compounds Emissions in Captured Stream

                        1. Scope and Application

    1.1 Applicability. This procedure is applicable for determining the 
volatile organic compounds (VOC) content of captured gas streams. It is 
intended to be used in the development of a gas/gas protocol for 
determining VOC capture efficiency (CE) for surface coating and printing 
operations. The procedure may not be acceptable in certain site-specific 
situations [e.g., when: (1) direct-fired heaters or other circumstances 
affect the quantity of VOC at the control device inlet; and (2) 
particulate organic aerosols are formed in the process and are present 
in the captured emissions].
    1.2 Principle. The amount of VOC captured (G) is calculated as the 
sum of the products of the VOC content (CGj), the flow rate 
(QGj), and the sample time ([Theta]C) from each 
captured emissions point.
    1.3 Sampling Requirements. A CE test shall consist of at least three 
sampling runs. Each run shall cover at least one complete production 
cycle, but shall be at least 3 hours long. The sampling time for each 
run need not exceed 8 hours, even if the production cycle has not been 
completed. Alternative sampling times may be used with the approval of 
the Administrator.

                          2. Summary of Method

    A gas sample is extracted from the source though a heated sample 
line and, if necessary, a glass fiber filter to a flame ionization 
analyzer (FIA).

                                3. Safety

    Because this procedure is often applied in highly explosive areas, 
caution and care should be exercised in choosing, installing, and using 
the appropriate equipment.

                        4. Equipment and Supplies

    Mention of trade names or company products does not constitute 
endorsement. All gas concentrations (percent, ppm) are by volume, unless 
otherwise noted.
    4.1 Gas VOC Concentration. A schematic of the measurement system is 
shown in Figure 204B-1. The main components are as follows:
    4.1.1 Sample Probe. Stainless steel or equivalent. The probe shall 
be heated to prevent VOC condensation.
    4.1.2 Calibration Valve Assembly. Three-way valve assembly at the 
outlet of the sample probe to direct the zero and calibration gases to 
the analyzer. Other methods, such as quick-connect lines, to route 
calibration gases to the outlet of the sample probe are acceptable.
    4.1.3 Sample Line. Stainless steel or Teflon tubing to transport the 
sample gas to the analyzer. The sample line must be heated to prevent 
condensation.
    4.1.4 Sample Pump. A leak-free pump, to pull the sample gas through 
the system at a flow rate sufficient to minimize the response time of 
the measurement system. The components of the pump that contact the gas 
stream shall be constructed of stainless steel or Teflon. The sample 
pump must be heated to prevent condensation.
    4.1.5 Sample Flow Rate Control. A sample flow rate control valve and 
rotameter, or equivalent, to maintain a constant sampling rate within 10 
percent. The flow rate control valve and rotameter must be heated to 
prevent condensation. A control valve may also be located on the sample 
pump bypass loop to assist in controlling the sample pressure and flow 
rate.
    4.1.6 Organic Concentration Analyzer. An FIA with a span value of 
1.5 times the expected concentration as propane; however, other span 
values may be used if it can be demonstrated to the Administrator's 
satisfaction that they would provide equally accurate measurements. The 
system shall be capable of meeting or exceeding the following 
specifications:
    4.1.6.1 Zero Drift. Less than 3.0 percent of 
the span value.
    4.1.6.2 Calibration Drift. Less than 3.0 
percent of the span value.
    4.1.6.3 Calibration Error. Less than 5.0 
percent of the calibration gas value.
    4.1.6.4 Response Time. Less than 30 seconds.
    4.1.7 Integrator/Data Acquisition System. An analog or digital 
device, or computerized data acquisition system used to integrate the 
FIA response or compute the average response and record measurement 
data. The minimum data sampling frequency for computing average or 
integrated values is one measurement value every 5 seconds. The device 
shall be capable of recording average values at least once per minute.
    4.2 Captured Emissions Volumetric Flow Rate.
    4.2.1 Method 2 or 2A Apparatus. For determining volumetric flow 
rate.
    4.2.2 Method 3 Apparatus and Reagents. For determining molecular 
weight of the gas stream. An estimate of the molecular weight of the gas 
stream may be used if approved by the Administrator.
    4.2.3 Method 4 Apparatus and Reagents. For determining moisture 
content, if necessary.

                        5. Reagents and Standards

    5.1 Calibration and Other Gases. Gases used for calibration, fuel, 
and combustion air (if required) are contained in compressed gas 
cylinders. All calibration gases shall be traceable to National 
Institute of Standards and Technology standards and shall be certified 
by the manufacturer to 1 percent of

[[Page 536]]

the tag value. Additionally, the manufacturer of the cylinder should 
provide a recommended shelf life for each calibration gas cylinder over 
which the concentration does not change more than 2 percent from the certified value. For calibration gas 
values not generally available, dilution systems calibrated using Method 
205 may be used. Alternative methods for preparing calibration gas 
mixtures may be used with the approval of the Administrator.
    5.1.1 Fuel. The FIA manufacturer's recommended fuel should be used. 
A 40 percent H2/60 percent He or 40 percent H2/60 
percent N2 gas mixture is recommended to avoid an oxygen 
synergism effect that reportedly occurs when oxygen concentration varies 
significantly from a mean value. Other mixtures may be used provided the 
tester can demonstrate to the Administrator that there is no oxygen 
synergism effect.
    5.1.2 Carrier Gas. High purity air with less than 1 ppm of organic 
material (as propane or carbon equivalent) or less than 0.1 percent of 
the span value, whichever is greater.
    5.1.3 FIA Linearity Calibration Gases. Low-, mid-, and high-range 
gas mixture standards with nominal propane concentrations of 20-30, 45-
55, and 70-80 percent of the span value in air, respectively. Other 
calibration values and other span values may be used if it can be shown 
to the Administrator's satisfaction that equally accurate measurements 
would be achieved.
    5.2 Particulate Filter. An in-stack or an out-of-stack glass fiber 
filter is recommended if exhaust gas particulate loading is significant. 
An out-of-stack filter must be heated to prevent any condensation unless 
it can be demonstrated that no condensation occurs.

                           6. Quality Control

    6.1 Required instrument quality control parameters are found in the 
following sections:
    6.1.1 The FIA system must be calibrated as specified in section 7.1.
    6.1.2 The system drift check must be performed as specified in 
section 7.2.
    6.1.3 The system check must be conducted as specified in section 
7.3.

                   7. Calibration and Standardization

    7.1 FIA Calibration and Linearity Check. Make necessary adjustments 
to the air and fuel supplies for the FIA and ignite the burner. Allow 
the FIA to warm up for the period recommended by the manufacturer. 
Inject a calibration gas into the measurement system and adjust the 
back-pressure regulator to the value required to achieve the flow rates 
specified by the manufacturer. Inject the zero-and the high-range 
calibration gases and adjust the analyzer calibration to provide the 
proper responses. Inject the low- and mid-range gases and record the 
responses of the measurement system. The calibration and linearity of 
the system are acceptable if the responses for all four gases are within 
5 percent of the respective gas values. If the performance of the system 
is not acceptable, repair or adjust the system and repeat the linearity 
check. Conduct a calibration and linearity check after assembling the 
analysis system and after a major change is made to the system.
    7.2 Systems Drift Checks. Select the calibration gas that most 
closely approximates the concentration of the captured emissions for 
conducting the drift checks. Introduce the zero and calibration gases at 
the calibration valve assembly and verify that the appropriate gas flow 
rate and pressure are present at the FIA. Record the measurement system 
responses to the zero and calibration gases. The performance of the 
system is acceptable if the difference between the drift check 
measurement and the value obtained in section 7.1 is less than 3 percent 
of the span value. Alternatively, recalibrate the FIA as in section 7.1 
and report the results using both sets of calibration data (i.e., data 
determined prior to the test period and data determined following the 
test period). The data that results in the lowest CE value shall be 
reported as the results for the test run. Conduct the system drift 
checks at the end of each run.
    7.3 System Check. Inject the high-range calibration gas at the inlet 
of the sampling probe and record the response. The performance of the 
system is acceptable if the measurement system response is within 5 
percent of the value obtained in section 7.1 for the high-range 
calibration gas. Conduct a system check before and after each test run.

                              8. Procedure

    8.1. Determination of Volumetric Flow Rate of Captured Emissions.
    8.1.1 Locate all points where emissions are captured from the 
affected facility. Using Method 1, determine the sampling points. Be 
sure to check each site for cyclonic or swirling flow.
    8.1.2 Measure the velocity at each sampling site at least once every 
hour during each sampling run using Method 2 or 2A.
    8.2 Determination of VOC Content of Captured Emissions.
    8.2.1 Analysis Duration. Measure the VOC responses at each captured 
emissions point during the entire test run or, if applicable, while the 
process is operating. If there are multiple captured emission locations, 
design a sampling system to allow a single FIA to be used to determine 
the VOC responses at all sampling locations.
    8.2.2 Gas VOC Concentration.
    8.2.2.1 Assemble the sample train as shown in Figure 204B-1. 
Calibrate the FIA according to the procedure in section 7.1.

[[Page 537]]

    8.2.2.2 Conduct a system check according to the procedure in section 
7.3.
    8.2.2.3 Install the sample probe so that the probe is centrally 
located in the stack, pipe, or duct, and is sealed tightly at the stack 
port connection.
    8.2.2.4 Inject zero gas at the calibration valve assembly. Allow the 
measurement system response to reach zero. Measure the system response 
time as the time required for the system to reach the effluent 
concentration after the calibration valve has been returned to the 
effluent sampling position.
    8.2.2.5 Conduct a system check before, and a system drift check 
after, each sampling run according to the procedures in sections 7.2 and 
7.3. If the drift check following a run indicates unacceptable 
performance (see section 7.3), the run is not valid. Alternatively, 
recalibrate the FIA as in section 7.1 and report the results using both 
sets of calibration data (i.e., data determined prior to the test period 
and data determined following the test period). The data that results in 
the lowest CE value shall be reported as the results for the test run. 
The tester may elect to perform system drift checks during the run not 
to exceed one drift check per hour.
    8.2.2.6 Verify that the sample lines, filter, and pump temperatures 
are 120 5 [deg]C.
    8.2.2.7 Begin sampling at the start of the test period and continue 
to sample during the entire run. Record the starting and ending times 
and any required process information as appropriate. If multiple 
captured emission locations are sampled using a single FIA, sample at 
each location for the same amount of time (e.g., 2 minutes) and continue 
to switch from one location to another for the entire test run. Be sure 
that total sampling time at each location is the same at the end of the 
test run. Collect at least four separate measurements from each sample 
point during each hour of testing. Disregard the measurements at each 
sampling location until two times the response time of the measurement 
system has elapsed. Continue sampling for at least 1 minute and record 
the concentration measurements.
    8.2.3 Background Concentration.

    Note: Not applicable when the building is used as the temporary 
total enclosure (TTE).

    8.2.3.1 Locate all natural draft openings (NDO's) of the TTE. A 
sampling point shall be at the center of each NDO, unless otherwise 
specified by the Administrator. If there are more than six NDO's, choose 
six sampling points evenly spaced among the NDO's.
    8.2.3.2 Assemble the sample train as shown in Figure 204B-2. 
Calibrate the FIA and conduct a system check according to the procedures 
in sections 7.1 and 7.3.

    Note: This sample train shall be separate from the sample train used 
to measure the captured emissions.

    8.2.3.3 Position the probe at the sampling location.
    8.2.3.4 Determine the response time, conduct the system check, and 
sample according to the procedures described in sections 8.2.2.4 through 
8.2.2.7.
    8.2.4 Alternative Procedure. The direct interface sampling and 
analysis procedure described in section 7.2 of Method 18 may be used to 
determine the gas VOC concentration. The system must be designed to 
collect and analyze at least one sample every 10 minutes. If the 
alternative procedure is used to determine the VOC concentration of the 
captured emissions, it must also be used to determine the VOC 
concentration of the uncaptured emissions.

                    9. Data Analysis and Calculations

    9.1 Nomenclature.

Ai = area of NDO i, ft\2\.
AN = total area of all NDO's in the enclosure, ft\2\.
CBi = corrected average VOC concentration of background 
          emissions at point i, ppm propane.
CB = average background concentration, ppm propane.
CGj = corrected average VOC concentration of captured 
          emissions at point j, ppm propane.
CDH = average measured concentration for the drift check 
          calibration gas, ppm propane.
CDO = average system drift check concentration for zero 
          concentration gas, ppm propane.
CH = actual concentration of the drift check calibration gas, 
          ppm propane.
Ci = uncorrected average background VOC concentration 
          measured at point i, ppm propane.
Cj = uncorrected average VOC concentration measured at point 
          j, ppm propane.
G = total VOC content of captured emissions, kg.
K1 = 1.830 x 10-6 kg/(m\3\-ppm).
n = number of measurement points.
QGj = average effluent volumetric flow rate corrected to 
          standard conditions at captured emissions point j, m\3\/min.
[Theta]C = total duration of captured emissions.
    9.2 Calculations.
    9.2.1 Total VOC Captured Emissions.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.006
    
    9.2.2 VOC Concentration of the Captured Emissions at Point j.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.007
    

[[Page 538]]


    9.2.3 Background VOC Concentration at Point i.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.008
    
    9.2.4 Average Background Concentration.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.009
    
    Note: If the concentration at each point is within 20 percent of the 
average concentration of all points, then use the arithmetic average.

                         10. Method Performance

    The measurement uncertainties are estimated for each captured or 
uncaptured emissions point as follows: QGj=5.5 percent and CGj=5.0 
percent. Based on these numbers, the probable uncertainty for G is 
estimated at about 7.4 percent.

                              11. Diagrams

[[Page 539]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.027


[[Page 540]]


[GRAPHIC] [TIFF OMITTED] TR16JN97.028


[[Page 541]]



  Method 204C--Volatile Organic Compounds Emissions in Captured Stream 
                          (Dilution Technique)

                        1. Scope and Application

    1.1 Applicability. This procedure is applicable for determining the 
volatile organic compounds (VOC) content of captured gas streams. It is 
intended to be used in the development of a gas/gas protocol in which 
uncaptured emissions are also measured for determining VOC capture 
efficiency (CE) for surface coating and printing operations. A dilution 
system is used to reduce the VOC concentration of the captured emissions 
to about the same concentration as the uncaptured emissions. The 
procedure may not be acceptable in certain site-specific situations 
[e.g., when: (1) direct-fired heaters or other circumstances affect the 
quantity of VOC at the control device inlet; and (2) particulate organic 
aerosols are formed in the process and are present in the captured 
emissions].
    1.2 Principle. The amount of VOC captured (G) is calculated as the 
sum of the products of the VOC content (CGj), the flow rate 
(QGj), and the sampling time ([Theta]C) from each 
captured emissions point.
    1.3 Sampling Requirements. A CE test shall consist of at least three 
sampling runs. Each run shall cover at least one complete production 
cycle, but shall be at least 3 hours long. The sampling time for each 
run need not exceed 8 hours, even if the production cycle has not been 
completed. Alternative sampling times may be used with the approval of 
the Administrator.

                          2. Summary of Method

    A gas sample is extracted from the source using an in-stack dilution 
probe through a heated sample line and, if necessary, a glass fiber 
filter to a flame ionization analyzer (FIA). The sample train contains a 
sample gas manifold which allows multiple points to be sampled using a 
single FIA.

                                3. Safety

    Because this procedure is often applied in highly explosive areas, 
caution and care should be exercised in choosing, installing, and using 
the appropriate equipment.

                        4. Equipment and Supplies

    Mention of trade names or company products does not constitute 
endorsement. All gas concentrations (percent, ppm) are by volume, unless 
otherwise noted.
    4.1 Gas VOC Concentration. A schematic of the measurement system is 
shown in Figure 204C-1. The main components are as follows:
    4.1.1 Dilution System. A Kipp in-stack dilution probe and controller 
or similar device may be used. The dilution rate may be changed by 
substituting different critical orifices or adjustments of the aspirator 
supply pressure. The dilution system shall be heated to prevent VOC 
condensation. Note: An out-of-stack dilution device may be used.
    4.1.2 Calibration Valve Assembly. Three-way valve assembly at the 
outlet of the sample probe to direct the zero and calibration gases to 
the analyzer. Other methods, such as quick-connect lines, to route 
calibration gases to the outlet of the sample probe are acceptable.
    4.1.3 Sample Line. Stainless steel or Teflon tubing to transport the 
sample gas to the analyzer. The sample line must be heated to prevent 
condensation.
    4.1.4 Sample Pump. A leak-free pump, to pull the sample gas through 
the system at a flow rate sufficient to minimize the response time of 
the measurement system. The components of the pump that contact the gas 
stream shall be constructed of stainless steel or Teflon. The sample 
pump must be heated to prevent condensation.
    4.1.5 Sample Flow Rate Control. A sample flow rate control valve and 
rotameter, or equivalent, to maintain a constant sampling rate within 10 
percent. The flow control valve and rotameter must be heated to prevent 
condensation. A control valve may also be located on the sample pump 
bypass loop to assist in controlling the sample pressure and flow rate.
    4.1.6 Sample Gas Manifold. Capable of diverting a portion of the 
sample gas stream to the FIA, and the remainder to the bypass discharge 
vent. The manifold components shall be constructed of stainless steel or 
Teflon. If captured or uncaptured emissions are to be measured at 
multiple locations, the measurement system shall be designed to use 
separate sampling probes, lines, and pumps for each measurement location 
and a common sample gas manifold and FIA. The sample gas manifold and 
connecting lines to the FIA must be heated to prevent condensation.

    Note: Depending on the number of sampling points and their location, 
it may not be possible to use only one FIA. However to reduce the effect 
of calibration error, the number of FIA's used during a test should be 
keep as small as possible.

    4.1.7 Organic Concentration Analyzer. An FIA with a span value of 
1.5 times the expected concentration as propane; however, other span 
values may be used if it can be demonstrated to the Administrator's 
satisfaction that they would provide equally accurate measurements. The 
system shall be capable of meeting or exceeding the following 
specifications:
    4.1.7.1 Zero Drift. Less than 3.0 percent of 
the span value.
    4.1.7.2 Calibration Drift. Less than 3.0 
percent of the span value.

[[Page 542]]

    4.1.7.3 Calibration Error. Less than 5.0 
percent of the calibration gas value.
    4.1.7.4 Response Time. Less than 30 seconds.
    4.1.8 Integrator/Data Acquisition System. An analog or digital 
device or computerized data acquisition system used to integrate the FIA 
response or compute the average response and record measurement data. 
The minimum data sampling frequency for computing average or integrated 
values is one measurement value every 5 seconds. The device shall be 
capable of recording average values at least once per minute.
    4.2 Captured Emissions Volumetric Flow Rate.
    4.2.1 Method 2 or 2A Apparatus. For determining volumetric flow 
rate.
    4.2.2 Method 3 Apparatus and Reagents. For determining molecular 
weight of the gas stream. An estimate of the molecular weight of the gas 
stream may be used if approved by the Administrator.
    4.2.3 Method 4 Apparatus and Reagents. For determining moisture 
content, if necessary.

                        5. Reagents and Standards

    5.1 Calibration and Other Gases. Gases used for calibration, fuel, 
and combustion air (if required) are contained in compressed gas 
cylinders. All calibration gases shall be traceable to National 
Institute of Standards and Technology standards and shall be certified 
by the manufacturer to 1 percent of the tag value. 
Additionally, the manufacturer of the cylinder should provide a 
recommended shelf life for each calibration gas cylinder over which the 
concentration does not change more than 2 percent 
from the certified value. For calibration gas values not generally 
available, dilution systems calibrated using Method 205 may be used. 
Alternative methods for preparing calibration gas mixtures may be used 
with the approval of the Administrator.
    5.1.1 Fuel. The FIA manufacturer's recommended fuel should be used. 
A 40 percent H2/60 percent He or 40 percent H2/60 
percent N2 gas mixture is recommended to avoid an oxygen 
synergism effect that reportedly occurs when oxygen concentration varies 
significantly from a mean value. Other mixtures may be used provided the 
tester can demonstrate to the Administrator that there is no oxygen 
synergism effect
    5.1.2 Carrier Gas and Dilution Air Supply. High purity air with less 
than 1 ppm of organic material (as propane or carbon equivalent), or 
less than 0.1 percent of the span value, whichever is greater.
    5.1.3 FIA Linearity Calibration Gases. Low-, mid-, and high-range 
gas mixture standards with nominal propane concentrations of 20-30, 45-
55, and 70-80 percent of the span value in air, respectively. Other 
calibration values and other span values may be used if it can be shown 
to the Administrator's satisfaction that equally accurate measurements 
would be achieved.
    5.1.4 Dilution Check Gas. Gas mixture standard containing propane in 
air, approximately half the span value after dilution.
    5.2 Particulate Filter. An in-stack or an out-of-stack glass fiber 
filter is recommended if exhaust gas particulate loading is significant. 
An out-of-stack filter must be heated to prevent any condensation unless 
it can be demonstrated that no condensation occurs.

                           6. Quality Control

    6.1 Required instrument quality control parameters are found in the 
following sections:
    6.1.1 The FIA system must be calibrated as specified in section 7.1.
    6.1.2 The system drift check must be performed as specified in 
section 7.2.
    6.1.3 The dilution factor must be determined as specified in section 
7.3.
    6.1.4 The system check must be conducted as specified in section 
7.4.

                   7. Calibration and Standardization

    7.1 FIA Calibration and Linearity Check. Make necessary adjustments 
to the air and fuel supplies for the FIA and ignite the burner. Allow 
the FIA to warm up for the period recommended by the manufacturer. 
Inject a calibration gas into the measurement system after the dilution 
system and adjust the back-pressure regulator to the value required to 
achieve the flow rates specified by the manufacturer. Inject the zero-
and the high-range calibration gases and adjust the analyzer calibration 
to provide the proper responses. Inject the low-and mid-range gases and 
record the responses of the measurement system. The calibration and 
linearity of the system are acceptable if the responses for all four 
gases are within 5 percent of the respective gas values. If the 
performance of the system is not acceptable, repair or adjust the system 
and repeat the linearity check. Conduct a calibration and linearity 
check after assembling the analysis system and after a major change is 
made to the system.
    7.2 Systems Drift Checks. Select the calibration gas that most 
closely approximates the concentration of the diluted captured emissions 
for conducting the drift checks. Introduce the zero and calibration 
gases at the calibration valve assembly, and verify that the appropriate 
gas flow rate and pressure are present at the FIA. Record the 
measurement system responses to the zero and calibration gases. The 
performance of the system is acceptable if the difference between the 
drift check measurement and the value obtained in section 7.1 is less 
than 3 percent of the span value. Alternatively, recalibrate the FIA as 
in section 7.1 and report

[[Page 543]]

the results using both sets of calibration data (i.e., data determined 
prior to the test period and data determined following the test period). 
The data that results in the lowest CE value shall be reported as the 
results for the test run. Conduct the system drift check at the end of 
each run.
    7.3 Determination of Dilution Factor. Inject the dilution check gas 
into the measurement system before the dilution system and record the 
response. Calculate the dilution factor using Equation 204C-3.
    7.4 System Check. Inject the high-range calibration gas at the inlet 
to the sampling probe while the dilution air is turned off. Record the 
response. The performance of the system is acceptable if the measurement 
system response is within 5 percent of the value obtained in section 7.1 
for the high-range calibration gas. Conduct a system check before and 
after each test run.

                              8. Procedure

    8.1 Determination of Volumetric Flow Rate of Captured Emissions
    8.1.1 Locate all points where emissions are captured from the 
affected facility. Using Method 1, determine the sampling points. Be 
sure to check each site for cyclonic or swirling flow.
    8.2.2 Measure the velocity at each sampling site at least once every 
hour during each sampling run using Method 2 or 2A.
    8.2 Determination of VOC Content of Captured Emissions
    8.2.1 Analysis Duration. Measure the VOC responses at each captured 
emissions point during the entire test run or, if applicable, while the 
process is operating. If there are multiple captured emissions 
locations, design a sampling system to allow a single FIA to be used to 
determine the VOC responses at all sampling locations.
    8.2.2 Gas VOC Concentration.
    8.2.2.1 Assemble the sample train as shown in Figure 204C-1. 
Calibrate the FIA according to the procedure in section 7.1.
    8.2.2.2 Set the dilution ratio and determine the dilution factor 
according to the procedure in section 7.3.
    8.2.2.3 Conduct a system check according to the procedure in section 
7.4.
    8.2.2.4 Install the sample probe so that the probe is centrally 
located in the stack, pipe, or duct, and is sealed tightly at the stack 
port connection.
    8.2.2.5 Inject zero gas at the calibration valve assembly. Measure 
the system response time as the time required for the system to reach 
the effluent concentration after the calibration valve has been returned 
to the effluent sampling position.
    8.2.2.6 Conduct a system check before, and a system drift check 
after, each sampling run according to the procedures in sections 7.2 and 
7.4. If the drift check following a run indicates unacceptable 
performance (see section 7.4), the run is not valid. Alternatively, 
recalibrate the FIA as in section 7.1 and report the results using both 
sets of calibration data (i.e., data determined prior to the test period 
and data determined following the test period). The data that results in 
the lowest CE value shall be reported as the results for the test run. 
The tester may elect to perform system drift checks during the run not 
to exceed one drift check per hour.
    8.2.2.7 Verify that the sample lines, filter, and pump temperatures 
are 120 5 [deg]C.
    8.2.2.8 Begin sampling at the start of the test period and continue 
to sample during the entire run. Record the starting and ending times 
and any required process information as appropriate. If multiple 
captured emission locations are sampled using a single FIA, sample at 
each location for the same amount of time (e.g., 2 min.) and continue to 
switch from one location to another for the entire test run. Be sure 
that total sampling time at each location is the same at the end of the 
test run. Collect at least four separate measurements from each sample 
point during each hour of testing. Disregard the measurements at each 
sampling location until two times the response time of the measurement 
system has elapsed. Continue sampling for at least 1 minute and record 
the concentration measurements.
    8.2.3 Background Concentration.

    Note: Not applicable when the building is used as the temporary 
total enclosure (TTE).

    8.2.3.1 Locate all natural draft openings (NDO's) of the TTE. A 
sampling point shall be at the center of each NDO, unless otherwise 
approved by the Administrator. If there are more than six NDO's, choose 
six sampling points evenly spaced among the NDO's.
    8.2.3.2 Assemble the sample train as shown in Figure 204C-2. 
Calibrate the FIA and conduct a system check according to the procedures 
in sections 7.1 and 7.4.
    8.2.3.3 Position the probe at the sampling location.
    8.2.3.4 Determine the response time, conduct the system check, and 
sample according to the procedures described in sections 8.2.2.4 through 
8.2.2.8.
    8.2.4 Alternative Procedure. The direct interface sampling and 
analysis procedure described in section 7.2 of Method 18 may be used to 
determine the gas VOC concentration. The system must be designed to 
collect and analyze at least one sample every 10 minutes. If the 
alternative procedure is used to determine the VOC concentration of the 
captured emissions, it must also be used to determine the VOC 
concentration of the uncaptured emissions.

                    9. Data Analysis and Calculations

    9.1 Nomenclature.

Ai = area of NDO i, ft\2\.

[[Page 544]]

AN = total area of all NDO's in the enclosure, ft\2\.
CA = actual concentration of the dilution check gas, ppm 
          propane.
CBi = corrected average VOC concentration of background 
          emissions at point i, ppm propane.
CB = average background concentration, ppm propane.
CDH = average measured concentration for the drift check 
          calibration gas, ppm propane.
CD0 = average system drift check concentration for zero 
          concentration gas, ppm propane.
CH = actual concentration of the drift check calibration gas, 
          ppm propane.
Ci = uncorrected average background VOC concentration 
          measured at point i, ppm propane.
Cj = uncorrected average VOC concentration measured at point 
          j, ppm propane.
CM = measured concentration of the dilution check gas, ppm 
          propane.
DF = dilution factor.
G = total VOC content of captured emissions, kg.
K1 = 1.830 x 10-6 kg/(m\3\-ppm).
n = number of measurement points.
QGj = average effluent volumetric flow rate corrected to 
          standard conditions at captured emissions point j, m\3\/min.
[Theta]C = total duration of CE sampling run, min.
    9.2 Calculations.
    9.2.1 Total VOC Captured Emissions.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.010
    
    9.2.2 VOC Concentration of the Captured Emissions at Point j.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.011
    
    9.2.3 Dilution Factor.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.012
    
    9.2.4 Background VOC Concentration at Point i.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.013
    
    9.2.5 Average Background Concentration.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.014
    
    Note: If the concentration at each point is within 20 percent of the 
average concentration of all points, then use the arithmetic average.

                         10. Method Performance

    The measurement uncertainties are estimated for each captured or 
uncaptured emissions point as follows: QGj=5.5 percent and CGj= 5 
percent. Based on these numbers, the probable uncertainty for G is 
estimated at about 7.4 percent.

                              11. Diagrams

[[Page 545]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.029


[[Page 546]]


[GRAPHIC] [TIFF OMITTED] TR16JN97.030

 Method 204D--Volatile Organic Compounds Emissions in Uncaptured Stream 
                     From Temporary Total Enclosure

                        1. Scope and Application

    1.1 Applicability. This procedure is applicable for determining the 
uncaptured volatile organic compounds (VOC) emissions from a temporary 
total enclosure (TTE). It is intended to be used as a segment in the 
development of liquid/gas or gas/gas protocols for determining VOC 
capture efficiency (CE) for surface coating and printing operations.

[[Page 547]]

    1.2 Principle. The amount of uncaptured VOC emissions (F) from the 
TTE is calculated as the sum of the products of the VOC content 
(CFj), the flow rate (QFj) from each uncaptured 
emissions point, and the sampling time ([Theta]F).
    1.3 Sampling Requirements. A CE test shall consist of at least three 
sampling runs. Each run shall cover at least one complete production 
cycle, but shall be at least 3 hours long. The sampling time for each 
run need not exceed 8 hours, even if the production cycle has not been 
completed. Alternative sampling times may be used with the approval of 
the Administrator.

                          2. Summary of Method

    A gas sample is extracted from the uncaptured exhaust duct of a TTE 
through a heated sample line and, if necessary, a glass fiber filter to 
a flame ionization analyzer (FIA).

                                3. Safety

    Because this procedure is often applied in highly explosive areas, 
caution and care should be exercised in choosing, installing, and using 
the appropriate equipment.

                        4. Equipment and Supplies

    Mention of trade names or company products does not constitute 
endorsement. All gas concentrations (percent, ppm) are by volume, unless 
otherwise noted.
    4.1 Gas VOC Concentration. A schematic of the measurement system is 
shown in Figure 204D-1. The main components are as follows:
    4.1.1 Sample Probe. Stainless steel or equivalent. The probe shall 
be heated to prevent VOC condensation.
    4.1.2 Calibration Valve Assembly. Three-way valve assembly at the 
outlet of the sample probe to direct the zero and calibration gases to 
the analyzer. Other methods, such as quick-connect lines, to route 
calibration gases to the outlet of the sample probe are acceptable.
    4.1.3 Sample Line. Stainless steel or Teflon tubing to transport the 
sample gas to the analyzer. The sample line must be heated to prevent 
condensation.
    4.1.4 Sample Pump. A leak-free pump, to pull the sample gas through 
the system at a flow rate sufficient to minimize the response time of 
the measurement system. The components of the pump that contact the gas 
stream shall be constructed of stainless steel or Teflon. The sample 
pump must be heated to prevent condensation.
    4.1.5 Sample Flow Rate Control. A sample flow rate control valve and 
rotameter, or equivalent, to maintain a constant sampling rate within 10 
percent. The flow control valve and rotameter must be heated to prevent 
condensation. A control valve may also be located on the sample pump 
bypass loop to assist in controlling the sample pressure and flow rate.
    4.1.6 Sample Gas Manifold. Capable of diverting a portion of the 
sample gas stream to the FIA, and the remainder to the bypass discharge 
vent. The manifold components shall be constructed of stainless steel or 
Teflon. If emissions are to be measured at multiple locations, the 
measurement system shall be designed to use separate sampling probes, 
lines, and pumps for each measurement location and a common sample gas 
manifold and FIA. The sample gas manifold and connecting lines to the 
FIA must be heated to prevent condensation.
    4.1.7 Organic Concentration Analyzer. An FIA with a span value of 
1.5 times the expected concentration as propane; however, other span 
values may be used if it can be demonstrated to the Administrator's 
satisfaction that they would provide more accurate measurements. The 
system shall be capable of meeting or exceeding the following 
specifications:
    4.1.7.1 Zero Drift. Less than 3.0 percent of 
the span value.
    4.1.7.2 Calibration Drift. Less than 3.0 
percent of the span value.
    4.1.7.3 Calibration Error. Less than 5.0 
percent of the calibration gas value.
    4.1.7.4 Response Time. Less than 30 seconds.
    4.1.8 Integrator/Data Acquisition System. An analog or digital 
device or computerized data acquisition system used to integrate the FIA 
response or compute the average response and record measurement data. 
The minimum data sampling frequency for computing average or integrated 
values is one measurement value every 5 seconds. The device shall be 
capable of recording average values at least once per minute.
    4.2 Uncaptured Emissions Volumetric Flow Rate.
    4.2.1 Method 2 or 2A Apparatus. For determining volumetric flow 
rate.
    4.2.2 Method 3 Apparatus and Reagents. For determining molecular 
weight of the gas stream. An estimate of the molecular weight of the gas 
stream may be used if approved by the Administrator.
    4.2.3 Method 4 Apparatus and Reagents. For determining moisture 
content, if necessary.
    4.3 Temporary Total Enclosure. The criteria for designing an 
acceptable TTE are specified in Method 204.

                        5. Reagents and Standards

    5.1 Calibration and Other Gases. Gases used for calibration, fuel, 
and combustion air (if required) are contained in compressed gas 
cylinders. All calibration gases shall be traceable to National 
Institute of Standards and Technology standards and shall be certified 
by the manufacturer to 1 percent of

[[Page 548]]

the tag value. Additionally, the manufacturer of the cylinder should 
provide a recommended shelf life for each calibration gas cylinder over 
which the concentration does not change more than 2 percent from the certified value. For calibration gas 
values not generally available, dilution systems calibrated using Method 
205 may be used. Alternative methods for preparing calibration gas 
mixtures may be used with the approval of the Administrator.
    5.1.1 Fuel. The FIA manufacturer's recommended fuel should be used. 
A 40 percent H2/60 percent He or 40 percent H2/60 
percent N2 gas mixture is recommended to avoid an oxygen 
synergism effect that reportedly occurs when oxygen concentration varies 
significantly from a mean value. Other mixtures may be used provided the 
tester can demonstrate to the Administrator that there is no oxygen 
synergism effect.
    5.1.2 Carrier Gas. High purity air with less than 1 ppm of organic 
material (as propane or carbon equivalent) or less than 0.1 percent of 
the span value, whichever is greater.
    5.1.3 FIA Linearity Calibration Gases. Low-, mid-, and high-range 
gas mixture standards with nominal propane concentrations of 20-30, 45-
55, and 70-80 percent of the span value in air, respectively. Other 
calibration values and other span values may be used if it can be shown 
to the Administrator's satisfaction that equally accurate measurements 
would be achieved.
    5.2 Particulate Filter. An in-stack or an out-of-stack glass fiber 
filter is recommended if exhaust gas particulate loading is significant. 
An out-of-stack filter must be heated to prevent any condensation unless 
it can be demonstrated that no condensation occurs.

                           6. Quality Control

    6.1 Required instrument quality control parameters are found in the 
following sections:
    6.1.1 The FIA system must be calibrated as specified in section 7.1.
    6.1.2 The system drift check must be performed as specified in 
section 7.2.
    6.1.3 The system check must be conducted as specified in section 
7.3.

                   7. Calibration and Standardization

    7.1 FIA Calibration and Linearity Check. Make necessary adjustments 
to the air and fuel supplies for the FIA and ignite the burner. Allow 
the FIA to warm up for the period recommended by the manufacturer. 
Inject a calibration gas into the measurement system and adjust the 
back-pressure regulator to the value required to achieve the flow rates 
specified by the manufacturer. Inject the zero-and the high-range 
calibration gases and adjust the analyzer calibration to provide the 
proper responses. Inject the low-and mid-range gases and record the 
responses of the measurement system. The calibration and linearity of 
the system are acceptable if the responses for all four gases are within 
5 percent of the respective gas values. If the performance of the system 
is not acceptable, repair or adjust the system and repeat the linearity 
check. Conduct a calibration and linearity check after assembling the 
analysis system and after a major change is made to the system.
    7.2 Systems Drift Checks. Select the calibration gas concentration 
that most closely approximates that of the uncaptured gas emissions 
concentration to conduct the drift checks. Introduce the zero and 
calibration gases at the calibration valve assembly and verify that the 
appropriate gas flow rate and pressure are present at the FIA. Record 
the measurement system responses to the zero and calibration gases. The 
performance of the system is acceptable if the difference between the 
drift check measurement and the value obtained in section 7.1 is less 
than 3 percent of the span value. Alternatively, recalibrate the FIA as 
in section 7.1 and report the results using both sets of calibration 
data (i.e., data determined prior to the test period and data determined 
following the test period). The data that results in the lowest CE value 
shall be reported as the results for the test run. Conduct a system 
drift check at the end of each run.
    7.3 System Check. Inject the high-range calibration gas at the inlet 
of the sampling probe and record the response. The performance of the 
system is acceptable if the measurement system response is within 5 
percent of the value obtained in section 7.1 for the high-range 
calibration gas. Conduct a system check before each test run.

                              8. Procedure

    8.1 Determination of Volumetric Flow Rate of Uncaptured Emissions
    8.1.1 Locate all points where uncaptured emissions are exhausted 
from the TTE. Using Method 1, determine the sampling points. Be sure to 
check each site for cyclonic or swirling flow.
    8.1.2 Measure the velocity at each sampling site at least once every 
hour during each sampling run using Method 2 or 2A.
    8.2 Determination of VOC Content of Uncaptured Emissions.
    8.2.1 Analysis Duration. Measure the VOC responses at each 
uncaptured emission point during the entire test run or, if applicable, 
while the process is operating. If there are multiple emission 
locations, design a sampling system to allow a single FIA to be used to 
determine the VOC responses at all sampling locations.
    8.2.2 Gas VOC Concentration.
    8.2.2.1 Assemble the sample train as shown in Figure 204D-1. 
Calibrate the FIA and conduct a system check according to the

[[Page 549]]

procedures in sections 7.1 and 7.3, respectively.
    8.2.2.2 Install the sample probe so that the probe is centrally 
located in the stack, pipe, or duct, and is sealed tightly at the stack 
port connection.
    8.2.2.3 Inject zero gas at the calibration valve assembly. Allow the 
measurement system response to reach zero. Measure the system response 
time as the time required for the system to reach the effluent 
concentration after the calibration valve has been returned to the 
effluent sampling position.
    8.2.2.4 Conduct a system check before, and a system drift check 
after, each sampling run according to the procedures in sections 7.2 and 
7.3. If the drift check following a run indicates unacceptable 
performance (see section 7.3), the run is not valid. Alternatively, 
recalibrate the FIA as in section 7.1 and report the results using both 
sets of calibration data (i.e., data determined prior to the test period 
and data determined following the test period). The data that results in 
the lowest CE value shall be reported as the results for the test run. 
The tester may elect to perform system drift checks during the run not 
to exceed one drift check per hour.
    8.2.2.5 Verify that the sample lines, filter, and pump temperatures 
are 120 5 [deg]C.
    8.2.2.6 Begin sampling at the start of the test period and continue 
to sample during the entire run. Record the starting and ending times 
and any required process information, as appropriate. If multiple 
emission locations are sampled using a single FIA, sample at each 
location for the same amount of time (e.g., 2 min.) and continue to 
switch from one location to another for the entire test run. Be sure 
that total sampling time at each location is the same at the end of the 
test run. Collect at least four separate measurements from each sample 
point during each hour of testing. Disregard the response measurements 
at each sampling location until 2 times the response time of the 
measurement system has elapsed. Continue sampling for at least 1 minute 
and record the concentration measurements.
    8.2.3 Background Concentration.
    8.2.3.1 Locate all natural draft openings (NDO's) of the TTE. A 
sampling point shall be at the center of each NDO, unless otherwise 
approved by the Administrator. If there are more than six NDO's, choose 
six sampling points evenly spaced among the NDO's.
    8.2.3.2 Assemble the sample train as shown in Figure 204D-2. 
Calibrate the FIA and conduct a system check according to the procedures 
in sections 7.1 and 7.3.
    8.2.3.3 Position the probe at the sampling location.
    8.2.3.4 Determine the response time, conduct the system check, and 
sample according to the procedures described in sections 8.2.2.3 through 
8.2.2.6.
    8.2.4 Alternative Procedure. The direct interface sampling and 
analysis procedure described in section 7.2 of Method 18 may be used to 
determine the gas VOC concentration. The system must be designed to 
collect and analyze at least one sample every 10 minutes. If the 
alternative procedure is used to determine the VOC concentration of the 
uncaptured emissions in a gas/gas protocol, it must also be used to 
determine the VOC concentration of the captured emissions. If a tester 
wishes to conduct a liquid/gas protocol using a gas chromatograph, the 
tester must use Method 204F for the liquid steam. A gas chromatograph is 
not an acceptable alternative to the FIA in Method 204A.

                    9. Data Analysis and Calculations

    9.1 Nomenclature.
Ai = area of NDO i, ft\2\.
AN = total area of all NDO's in the enclosure, ft\2\.
CBi = corrected average VOC concentration of background 
          emissions at point i, ppm propane.
CB = average background concentration, ppm propane.
CDH = average measured concentration for the drift check 
          calibration gas, ppm propane.
CD0 = average system drift check concentration for zero 
          concentration gas, ppm propane.
CFj = corrected average VOC concentration of uncaptured 
          emissions at point j, ppm propane.
CH = actual concentration of the drift check calibration gas, 
          ppm propane.
Ci = uncorrected average background VOC concentration at 
          point i, ppm propane.
Cj = uncorrected average VOC concentration measured at point 
          j, ppm propane.
F = total VOC content of uncaptured emissions, kg.
K1 = 1.830 x 10-6 kg/(m\3\-ppm).
n = number of measurement points.
QFj = average effluent volumetric flow rate corrected to 
          standard conditions at uncaptured emissions point j, m\3\/min.
[Theta]F = total duration of uncaptured emissions sampling 
          run, min.
    9.2 Calculations.
    9.2.1 Total Uncaptured VOC Emissions.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.015
    
    9.2.2 VOC Concentration of the Uncaptured Emissions at Point j.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.016
    
    9.2.3 Background VOC Concentration at Point i.

[[Page 550]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.017

    9.2.4 Average Background Concentration.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.018
    
    Note: If the concentration at each point is within 20 percent of the 
average concentration of all points, use the arithmetic average.

                         10. Method Performance

    The measurement uncertainties are estimated for each uncaptured 
emission point as follows: QFj=5.5 
percent and CFj=5.0 percent. Based on 
these numbers, the probable uncertainty for F is estimated at about 
7.4 percent.

                              11. Diagrams

[[Page 551]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.031


[[Page 552]]


[GRAPHIC] [TIFF OMITTED] TR16JN97.032


[[Page 553]]



 Method 204E--Volatile Organic Compounds Emissions in Uncaptured Stream 
                         From Building Enclosure

                        1. Scope and Application

    1.1 Applicability. This procedure is applicable for determining the 
uncaptured volatile organic compounds (VOC) emissions from a building 
enclosure (BE). It is intended to be used in the development of liquid/
gas or gas/gas protocols for determining VOC capture efficiency (CE) for 
surface coating and printing operations.
    1.2 Principle. The total amount of uncaptured VOC emissions 
(FB) from the BE is calculated as the sum of the products of 
the VOC content (CFj) of each uncaptured emissions point, the 
flow rate (QFj) at each uncaptured emissions point, and time 
([Theta]F).
    1.3 Sampling Requirements. A CE test shall consist of at least three 
sampling runs. Each run shall cover at least one complete production 
cycle, but shall be at least 3 hours long. The sampling time for each 
run need not exceed 8 hours, even if the production cycle has not been 
completed. Alternative sampling times may be used with the approval of 
the Administrator.

                          2. Summary of Method

    A gas sample is extracted from the uncaptured exhaust duct of a BE 
through a heated sample line and, if necessary, a glass fiber filter to 
a flame ionization analyzer (FIA).

                                3. Safety

    Because this procedure is often applied in highly explosive areas, 
caution and care should be exercised in choosing, installing, and using 
the appropriate equipment.

                        4. Equipment and Supplies

    Mention of trade names or company products does not constitute 
endorsement. All gas concentrations (percent, ppm) are by volume, unless 
otherwise noted.
    4.1 Gas VOC Concentration. A schematic of the measurement system is 
shown in Figure 204E-1. The main components are as follows:
    4.1.1 Sample Probe. Stainless steel or equivalent. The probe shall 
be heated to prevent VOC condensation.
    4.1.2 Calibration Valve Assembly. Three-way valve assembly at the 
outlet of the sample probe to direct the zero and calibration gases to 
the analyzer. Other methods, such as quick-connect lines, to route 
calibration gases to the outlet of the sample probe are acceptable.
    4.1.3 Sample Line. Stainless steel or Teflon tubing to transport the 
sample gas to the analyzer. The sample line must be heated to prevent 
condensation.
    4.1.4 Sample Pump. A leak-free pump, to pull the sample gas through 
the system at a flow rate sufficient to minimize the response time of 
the measurement system. The components of the pump that contact the gas 
stream shall be constructed of stainless steel or Teflon. The sample 
pump must be heated to prevent condensation.
    4.1.5 Sample Flow Rate Control. A sample flow rate control valve and 
rotameter, or equivalent, to maintain a constant sampling rate within 10 
percent. The flow rate control valve and rotameter must be heated to 
prevent condensation. A control valve may also be located on the sample 
pump bypass loop to assist in controlling the sample pressure and flow 
rate.
    4.1.6 Sample Gas Manifold. Capable of diverting a portion of the 
sample gas stream to the FIA, and the remainder to the bypass discharge 
vent. The manifold components shall be constructed of stainless steel or 
Teflon. If emissions are to be measured at multiple locations, the 
measurement system shall be designed to use separate sampling probes, 
lines, and pumps for each measurement location, and a common sample gas 
manifold and FIA. The sample gas manifold must be heated to prevent 
condensation.
    4.1.7 Organic Concentration Analyzer. An FIA with a span value of 
1.5 times the expected concentration as propane; however, other span 
values may be used if it can be demonstrated to the Administrator's 
satisfaction that they would provide equally accurate measurements. The 
system shall be capable of meeting or exceeding the following 
specifications:
    4.1.7.1 Zero Drift. Less than 3.0 percent of 
the span value.
    4.1.7.2 Calibration Drift. Less than 3.0 
percent of the span value.
    4.1.7.3 Calibration Error. Less than 5.0 
percent of the calibration gas value.
    4.1.7.4 Response Time. Less than 30 seconds.
    4.1.8 Integrator/Data Acquisition System. An analog or digital 
device or computerized data acquisition system used to integrate the FIA 
response or compute the average response and record measurement data. 
The minimum data sampling frequency for computing average or integrated 
values is one measurement value every 5 seconds. The device shall be 
capable of recording average values at least once per minute.
    4.2 Uncaptured Emissions Volumetric Flow Rate.
    4.2.1 Flow Direction Indicators. Any means of indicating inward or 
outward flow, such as light plastic film or paper streamers, smoke 
tubes, filaments, and sensory perception.
    4.2.2 Method 2 or 2A Apparatus. For determining volumetric flow 
rate. Anemometers or similar devices calibrated according to the 
manufacturer's instructions may be used

[[Page 554]]

when low velocities are present. Vane anemometers (Young-maximum 
response propeller), specialized pitots with electronic manometers 
(e.g., Shortridge Instruments Inc., Airdata Multimeter 860) are 
commercially available with measurement thresholds of 15 and 8 mpm (50 
and 25 fpm), respectively.
    4.2.3 Method 3 Apparatus and Reagents. For determining molecular 
weight of the gas stream. An estimate of the molecular weight of the gas 
stream may be used if approved by the Administrator.
    4.2.4 Method 4 Apparatus and Reagents. For determining moisture 
content, if necessary.
    4.3 Building Enclosure. The criteria for an acceptable BE are 
specified in Method 204.

                        5. Reagents and Standards

    5.1 Calibration and Other Gases. Gases used for calibration, fuel, 
and combustion air (if required) are contained in compressed gas 
cylinders. All calibration gases shall be traceable to National 
Institute of Standards and Technology standards and shall be certified 
by the manufacturer to 1 percent of the tag value. 
Additionally, the manufacturer of the cylinder should provide a 
recommended shelf life for each calibration gas cylinder over which the 
concentration does not change more than 2 percent 
from the certified value. For calibration gas values not generally 
available, dilution systems calibrated using Method 205 may be used. 
Alternative methods for preparing calibration gas mixtures may be used 
with the approval of the Administrator.
    5.1.1 Fuel. The FIA manufacturer's recommended fuel should be used. 
A 40 percent H2/60 percent He or 40 percent H2/60 
percent N2 gas mixture is recommended to avoid an oxygen 
synergism effect that reportedly occurs when oxygen concentration varies 
significantly from a mean value. Other mixtures may be used provided the 
tester can demonstrate to the Administrator that there is no oxygen 
synergism effect.
    5.1.2 Carrier Gas. High purity air with less than 1 ppm of organic 
material (propane or carbon equivalent) or less than 0.1 percent of the 
span value, whichever is greater.
    5.1.3 FIA Linearity Calibration Gases. Low-, mid-, and high-range 
gas mixture standards with nominal propane concentrations of 20-30, 45-
55, and 70-80 percent of the span value in air, respectively. Other 
calibration values and other span values may be used if it can be shown 
to the Administrator's satisfaction that equally accurate measurements 
would be achieved.
    5.2 Particulate Filter. An in-stack or an out-of-stack glass fiber 
filter is recommended if exhaust gas particulate loading is significant. 
An out-of-stack filter must be heated to prevent any condensation unless 
it can be demonstrated that no condensation occurs.

                           6. Quality Control

    6.1 Required instrument quality control parameters are found in the 
following sections:
    6.1.1 The FIA system must be calibrated as specified in section 7.1.
    6.1.2 The system drift check must be performed as specified in 
section 7.2.
    6.1.3 The system check must be conducted as specified in section 
7.3.

                   7. Calibration and Standardization

    7.1 FIA Calibration and Linearity Check. Make necessary adjustments 
to the air and fuel supplies for the FIA and ignite the burner. Allow 
the FIA to warm up for the period recommended by the manufacturer. 
Inject a calibration gas into the measurement system and adjust the 
back-pressure regulator to the value required to achieve the flow rates 
specified by the manufacturer. Inject the zero-and the high-range 
calibration gases, and adjust the analyzer calibration to provide the 
proper responses. Inject the low-and mid-range gases and record the 
responses of the measurement system. The calibration and linearity of 
the system are acceptable if the responses for all four gases are within 
5 percent of the respective gas values. If the performance of the system 
is not acceptable, repair or adjust the system and repeat the linearity 
check. Conduct a calibration and linearity check after assembling the 
analysis system and after a major change is made to the system.
    7.2 Systems Drift Checks. Select the calibration gas that most 
closely approximates the concentration of the captured emissions for 
conducting the drift checks. Introduce the zero and calibration gases at 
the calibration valve assembly and verify that the appropriate gas flow 
rate and pressure are present at the FIA. Record the measurement system 
responses to the zero and calibration gases. The performance of the 
system is acceptable if the difference between the drift check 
measurement and the value obtained in section 7.1 is less than 3 percent 
of the span value. Alternatively, recalibrate the FIA as in section 7.1 
and report the results using both sets of calibration data (i.e., data 
determined prior to the test period and data determined following the 
test period). The data that results in the lowest CE value shall be 
reported as the results for the test run. Conduct a system drift check 
at the end of each run.
    7.3 System Check. Inject the high-range calibration gas at the inlet 
of the sampling probe and record the response. The performance of the 
system is acceptable if the measurement system response is within 5 
percent of the value obtained in section 7.1 for the

[[Page 555]]

high-range calibration gas. Conduct a system check before each test run.

                              8. Procedure

    8.1 Preliminary Determinations. The following points are considered 
exhaust points and should be measured for volumetric flow rates and VOC 
concentrations:
    8.1.1 Forced Draft Openings. Any opening in the facility with an 
exhaust fan. Determine the volumetric flow rate according to Method 2.
    8.1.2 Roof Openings. Any openings in the roof of a facility which 
does not contain fans are considered to be exhaust points. Determine 
volumetric flow rate from these openings. Use the appropriate velocity 
measurement devices (e.g., propeller anemometers).
    8.2 Determination of Flow Rates.
    8.2.1 Measure the volumetric flow rate at all locations identified 
as exhaust points in section 8.1. Divide each exhaust opening into nine 
equal areas for rectangular openings and into eight equal areas for 
circular openings.
    8.2.2 Measure the velocity at each site at least once every hour 
during each sampling run using Method 2 or 2A, if applicable, or using 
the low velocity instruments in section 4.2.2.
    8.3 Determination of VOC Content of Uncaptured Emissions.
    8.3.1 Analysis Duration. Measure the VOC responses at each 
uncaptured emissions point during the entire test run or, if applicable, 
while the process is operating. If there are multiple emissions 
locations, design a sampling system to allow a single FIA to be used to 
determine the VOC responses at all sampling locations.
    8.3.2 Gas VOC Concentration.
    8.3.2.1 Assemble the sample train as shown in Figure 204E-1. 
Calibrate the FIA and conduct a system check according to the procedures 
in sections 7.1 and 7.3, respectively.
    8.3.2.2 Install the sample probe so that the probe is centrally 
located in the stack, pipe, or duct, and is sealed tightly at the stack 
port connection.
    8.3.2.3 Inject zero gas at the calibration valve assembly. Allow the 
measurement system response to reach zero. Measure the system response 
time as the time required for the system to reach the effluent 
concentration after the calibration valve has been returned to the 
effluent sampling position.
    8.3.2.4 Conduct a system check before, and a system drift check 
after, each sampling run according to the procedures in sections 7.2 and 
7.3. If the drift check following a run indicates unacceptable 
performance (see section 7.3), the run is not valid. Alternatively, 
recalibrate the FIA as in section 7.1 and report the results using both 
sets of calibration data (i.e., data determined prior to the test period 
and data determined following the test period). The data that results in 
the lowest CE value shall be reported as the results for the test run. 
The tester may elect to perform drift checks during the run, not to 
exceed one drift check per hour.
    8.3.2.5 Verify that the sample lines, filter, and pump temperatures 
are 120 5 [deg]C.
    8.3.2.6 Begin sampling at the start of the test period and continue 
to sample during the entire run. Record the starting and ending times, 
and any required process information, as appropriate. If multiple 
emission locations are sampled using a single FIA, sample at each 
location for the same amount of time (e.g., 2 minutes) and continue to 
switch from one location to another for the entire test run. Be sure 
that total sampling time at each location is the same at the end of the 
test run. Collect at least four separate measurements from each sample 
point during each hour of testing. Disregard the response measurements 
at each sampling location until 2 times the response time of the 
measurement system has elapsed. Continue sampling for at least 1 minute, 
and record the concentration measurements.
    8.4 Alternative Procedure. The direct interface sampling and 
analysis procedure described in section 7.2 of Method 18 may be used to 
determine the gas VOC concentration. The system must be designed to 
collect and analyze at least one sample every 10 minutes. If the 
alternative procedure is used to determine the VOC concentration of the 
uncaptured emissions in a gas/gas protocol, it must also be used to 
determine the VOC concentration of the captured emissions. If a tester 
wishes to conduct a liquid/gas protocol using a gas chromatograph, the 
tester must use Method 204F for the liquid steam. A gas chromatograph is 
not an acceptable alternative to the FIA in Method 204A.

                    9. Data Analysis and Calculations

    9.1 Nomenclature.
CDH = average measured concentration for the drift check 
          calibration gas, ppm propane.
CD0 = average system drift check concentration for zero 
          concentration gas, ppm propane.
CFj = corrected average VOC concentration of uncaptured 
          emissions at point j, ppm propane.
CH = actual concentration of the drift check calibration gas, 
          ppm propane.
Cj = uncorrected average VOC concentration measured at point 
          j, ppm propane.
FB = total VOC content of uncaptured emissions from the 
          building, kg.
K1 = 1.830 x 10-6 kg/(m\3\-ppm).
n = number of measurement points.
QFj = average effluent volumetric flow rate corrected to 
          standard conditions at uncaptured emissions point j, m\3\/min.
[Theta]F = total duration of CE sampling run, min.


[[Page 556]]


    9.2 Calculations
    9.2.1 Total VOC Uncaptured Emissions from the Building.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.019
    
    9.2.2 VOC Concentration of the Uncaptured Emissions at Point j.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.020
    
                         10. Method Performance

    The measurement uncertainties are estimated for each uncaptured 
emissions point as follows: QFj=10.0 
percent and CFj=5.0 percent. Based on 
these numbers, the probable uncertainty for FB is estimated 
at about 11.2 percent.

                              11. Diagrams

[[Page 557]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.033

 Method 204F--Volatile Organic Compounds Content in Liquid Input Stream 
                         (Distillation Approach)

                             1. Introduction

    1.1 Applicability. This procedure is applicable for determining the 
input of volatile organic compounds (VOC). It is intended to be used as 
a segment in the development of liquid/gas protocols for determining VOC 
capture efficiency (CE) for surface coating and printing operations.
    1.2 Principle. The amount of VOC introduced to the process (L) is 
the sum of the products of the weight (W) of each VOC containing liquid 
(ink, paint, solvent, etc.) used,

[[Page 558]]

and its VOC content (V), corrected for a response factor (RF).
    1.3 Sampling Requirements. A CE test shall consist of at least three 
sampling runs. Each run shall cover at least one complete production 
cycle, but shall be at least 3 hours long. The sampling time for each 
run need not exceed 8 hours, even if the production cycle has not been 
completed. Alternative sampling times may be used with the approval of 
the Administrator.

                          2. Summary of Method

    A sample of each coating used is distilled to separate the VOC 
fraction. The distillate is used to prepare a known standard for 
analysis by a flame ionization analyzer (FIA), calibrated against 
propane, to determine its RF.

                                3. Safety

    Because this procedure is often applied in highly explosive areas, 
caution and care should be exercised in choosing, installing, and using 
the appropriate equipment.

                        4. Equipment and Supplies

    Mention of trade names or company products does not constitute 
endorsement. All gas concentrations (percent, ppm) are by volume, unless 
otherwise noted.
    4.1 Liquid Weight.
    4.1.1 Balances/Digital Scales. To weigh drums of VOC containing 
liquids to within 0.2 lb or 1.0 percent of the total weight of VOC 
liquid used.
    4.1.2 Volume Measurement Apparatus (Alternative). Volume meters, 
flow meters, density measurement equipment, etc., as needed to achieve 
the same accuracy as direct weight measurements.
    4.2 Response Factor Determination (FIA Technique). The VOC 
distillation system and Tedlar gas bag generation system apparatuses are 
shown in Figures 204F-1 and 204F-2, respectively. The following 
equipment is required:
    4.2.1 Sample Collection Can. An appropriately-sized metal can to be 
used to collect VOC containing materials. The can must be constructed in 
such a way that it can be grounded to the coating container.
    4.2.2 Needle Valves. To control gas flow.
    4.2.3 Regulators. For calibration, dilution, and sweep gas 
cylinders.
    4.2.4 Tubing and Fittings. Teflon and stainless steel tubing and 
fittings with diameters, lengths, and sizes determined by the connection 
requirements of the equipment.
    4.2.5 Thermometer. Capable of measuring the temperature of the hot 
water and oil baths to within 1 [deg]C.
    4.2.6 Analytical Balance. To measure 0.01 mg.
    4.2.7 Microliter Syringe. 10-[micro]l size.
    4.2.8 Vacuum Gauge or Manometer. 0- to 760-mm (0- to 30-in.) Hg U-
Tube manometer or vacuum gauge.
    4.2.9 Hot Oil Bath, With Stirring Hot Plate. Capable of heating and 
maintaining a distillation vessel at 110 3 [deg]C.
    4.2.10 Ice Water Bath. To cool the distillation flask.
    4.2.11 Vacuum/Water Aspirator. A device capable of drawing a vacuum 
to within 20 mm Hg from absolute.
    4.2.12 Rotary Evaporator System. Complete with folded inner coil, 
vertical style condenser, rotary speed control, and Teflon sweep gas 
delivery tube with valved inlet. Buchi Rotavapor or equivalent.
    4.2.13 Ethylene Glycol Cooling/Circulating Bath. Capable of 
maintaining the condenser coil fluid at -10 [deg]C.
    4.2.14 Dry Gas Meter (DGM). Capable of measuring the dilution gas 
volume within 2 percent, calibrated with a spirometer or bubble meter, 
and equipped with a temperature gauge capable of measuring temperature 
within 3 [deg]C.
    4.2.15 Activated Charcoal/Mole Sieve Trap. To remove any trace level 
of organics picked up from the DGM.
    4.2.16 Gas Coil Heater. Sufficient length of 0.125-inch stainless 
steel tubing to allow heating of the dilution gas to near the water bath 
temperature before entering the volatilization vessel.
    4.2.17 Water Bath, With Stirring Hot Plate. Capable of heating and 
maintaining a volatilization vessel and coil heater at a temperature of 
100 5 [deg]C.
    4.2.18 Volatilization Vessel. 50-ml midget impinger fitted with a 
septum top and loosely filled with glass wool to increase the 
volatilization surface.
    4.2.19 Tedlar Gas Bag. Capable of holding 30 liters of gas, flushed 
clean with zero air, leak tested, and evacuated.
    4.2.20 Organic Concentration Analyzer. An FIA with a span value of 
1.5 times the expected concentration as propane; however, other span 
values may be used if it can be demonstrated that they would provide 
equally accurate measurements. The FIA instrument should be the same 
instrument used in the gaseous analyses adjusted with the same fuel, 
combustion air, and sample back-pressure (flow rate) settings. The 
system shall be capable of meeting or exceeding the following 
specifications:
    4.2.20.1 Zero Drift. Less than 3.0 percent of 
the span value.
    4.2.20.2 Calibration Drift. Less than 3.0 
percent of the span value.
    4.2.20.3 Calibration Error. Less than 3.0 
percent of the calibration gas value.
    4.2.21 Integrator/Data Acquisition System. An analog or digital 
device or computerized data acquisition system used to integrate the FIA 
response or compute the average response and record measurement data.

[[Page 559]]

The minimum data sampling frequency for computing average or integrated 
value is one measurement value every 5 seconds. The device shall be 
capable of recording average values at least once per minute.
    4.2.22 Chart Recorder (Optional). A chart recorder or similar device 
is recommended to provide a continuous analog display of the measurement 
results during the liquid sample analysis.

                        5. Reagents and Standards

    5.1 Zero Air. High purity air with less than 1 ppm of organic 
material (as propane) or less than 0.1 percent of the span value, 
whichever is greater. Used to supply dilution air for making the Tedlar 
bag gas samples.
    5.2 THC Free N2. High purity N2 with less than 
1 ppm THC. Used as sweep gas in the rotary evaporator system.
    5.3 Calibration and Other Gases. Gases used for calibration, fuel, 
and combustion air (if required) are contained in compressed gas 
cylinders. All calibration gases shall be traceable to National 
Institute of Standards and Technology standards and shall be certified 
by the manufacturer to 1 percent of the tag value. 
Additionally, the manufacturer of the cylinder should provide a 
recommended shelf life for each calibration gas cylinder over which the 
concentration does not change more than 2 percent 
from the certified value. For calibration gas values not generally 
available, dilution systems calibrated using Method 205 may be used. 
Alternative methods for preparing calibration gas mixtures may be used 
with the approval of the Administrator.
    5.3.1 Fuel. The FIA manufacturer's recommended fuel should be used. 
A 40 percent H2/60 percent He, or 40 percent H2/60 
percent N2 mixture is recommended to avoid fuels with oxygen 
to avoid an oxygen synergism effect that reportedly occurs when oxygen 
concentration varies significantly from a mean value. Other mixtures may 
be used provided the tester can demonstrate to the Administrator that 
there is no oxygen synergism effect.
    5.3.2 Combustion Air. High purity air with less than 1 ppm of 
organic material (as propane) or less than 0.1 percent of the span 
value, whichever is greater.
    5.3.3 FIA Linearity Calibration Gases. Low-, mid-, and high-range 
gas mixture standards with nominal propane concentration of 20-30, 45-
55, and 70-80 percent of the span value in air, respectively. Other 
calibration values and other span values may be used if it can be shown 
that equally accurate measurements would be achieved.
    5.3.4 System Calibration Gas. Gas mixture standard containing 
propane in air, approximating the VOC concentration expected for the 
Tedlar gas bag samples.

                           6. Quality Control

    6.1 Required instrument quality control parameters are found in the 
following sections:
    6.1.1 The FIA system must be calibrated as specified in section 7.1.
    6.1.2 The system drift check must be performed as specified in 
section 7.2.
    6.2 Precision Control. A minimum of one sample in each batch must be 
distilled and analyzed in duplicate as a precision control. If the 
results of the two analyses differ by more than 10 
percent of the mean, then the system must be reevaluated and the entire 
batch must be redistilled and analyzed.

                   7. Calibration and Standardization

    7.1 FIA Calibration and Linearity Check. Make necessary adjustments 
to the air and fuel supplies for the FIA and ignite the burner. Allow 
the FIA to warm up for the period recommended by the manufacturer. 
Inject a calibration gas into the measurement system and adjust the 
back-pressure regulator to the value required to achieve the flow rates 
specified by the manufacturer. Inject the zero-and the high-range 
calibration gases and adjust the analyzer calibration to provide the 
proper responses. Inject the low-and mid-range gases and record the 
responses of the measurement system. The calibration and linearity of 
the system are acceptable if the responses for all four gases are within 
5 percent of the respective gas values. If the performance of the system 
is not acceptable, repair or adjust the system and repeat the linearity 
check. Conduct a calibration and linearity check after assembling the 
analysis system and after a major change is made to the system. A 
calibration curve consisting of zero gas and two calibration levels must 
be performed at the beginning and end of each batch of samples.
    7.2 Systems Drift Checks. After each sample, repeat the system 
calibration checks in section 7.1 before any adjustments to the FIA or 
measurement system are made. If the zero or calibration drift exceeds 
3 percent of the span value, discard the result 
and repeat the analysis. Alternatively, recalibrate the FIA as in 
section 7.1 and report the results using both sets of calibration data 
(i.e., data determined prior to the test period and data determined 
following the test period). The data that results in the lowest CE value 
shall be reported as the results for the test run.

                              8. Procedures

    8.1 Determination of Liquid Input Weight
    8.1.1 Weight Difference. Determine the amount of material introduced 
to the process as the weight difference of the feed material before and 
after each sampling run. In determining the total VOC containing liquid

[[Page 560]]

usage, account for: (a) The initial (beginning) VOC containing liquid 
mixture; (b) any solvent added during the test run; (c) any coating 
added during the test run; and (d) any residual VOC containing liquid 
mixture remaining at the end of the sample run.
    8.1.1.1 Identify all points where VOC containing liquids are 
introduced to the process. To obtain an accurate measurement of VOC 
containing liquids, start with an empty fountain (if applicable). After 
completing the run, drain the liquid in the fountain back into the 
liquid drum (if possible), and weigh the drum again. Weigh the VOC 
containing liquids to 0.5 percent of the total 
weight (full) or 1.0 percent of the total weight 
of VOC containing liquid used during the sample run, whichever is less. 
If the residual liquid cannot be returned to the drum, drain the 
fountain into a preweighed empty drum to determine the final weight of 
the liquid.
    8.1.1.2 If it is not possible to measure a single representative 
mixture, then weigh the various components separately (e.g., if solvent 
is added during the sampling run, weigh the solvent before it is added 
to the mixture). If a fresh drum of VOC containing liquid is needed 
during the run, then weigh both the empty drum and fresh drum.
    8.1.2 Volume Measurement (Alternative). If direct weight 
measurements are not feasible, the tester may use volume meters and flow 
rate meters (and density measurements) to determine the weight of 
liquids used if it can be demonstrated that the technique produces 
results equivalent to the direct weight measurements. If a single 
representative mixture cannot be measured, measure the components 
separately.
    8.2 Determination of VOC Content in Input Liquids
    8.2.1 Collection of Liquid Samples.
    8.2.1.1 Collect a 1-pint or larger sample of the VOC containing 
liquid mixture at each application location at the beginning and end of 
each test run. A separate sample should be taken of each VOC containing 
liquid added to the application mixture during the test run. If a fresh 
drum is needed during the sampling run, then obtain a sample from the 
fresh drum.
    8.2.1.2 When collecting the sample, ground the sample container to 
the coating drum. Fill the sample container as close to the rim as 
possible to minimize the amount of headspace.
    8.2.1.3 After the sample is collected, seal the container so the 
sample cannot leak out or evaporate.
    8.2.1.4 Label the container to identify clearly the contents.
    8.2.2 Distillation of VOC.
    8.2.2.1 Assemble the rotary evaporator as shown in Figure 204F-1.
    8.2.2.2 Leak check the rotary evaporation system by aspirating a 
vacuum of approximately 20 mm Hg from absolute. Close up the system and 
monitor the vacuum for approximately 1 minute. If the vacuum falls more 
than 25 mm Hg in 1 minute, repair leaks and repeat. Turn off the 
aspirator and vent vacuum.
    8.2.2.3 Deposit approximately 20 ml of sample (inks, paints, etc.) 
into the rotary evaporation distillation flask.
    8.2.2.4 Install the distillation flask on the rotary evaporator.
    8.2.2.5 Immerse the distillate collection flask into the ice water 
bath.
    8.2.2.6 Start rotating the distillation flask at a speed of 
approximately 30 rpm.
    8.2.2.7 Begin heating the vessel at a rate of 2 to 3 [deg]C per 
minute.
    8.2.2.8 After the hot oil bath has reached a temperature of 50 
[deg]C or pressure is evident on the mercury manometer, turn on the 
aspirator and gradually apply a vacuum to the evaporator to within 20 mm 
Hg of absolute. Care should be taken to prevent material burping from 
the distillation flask.
    8.2.2.9 Continue heating until a temperature of 110 [deg]C is 
achieved and maintain this temperature for at least 2 minutes, or until 
the sample has dried in the distillation flask.
    8.2.2.10 Slowly introduce the N2 sweep gas through the 
purge tube and into the distillation flask, taking care to maintain a 
vacuum of approximately 400-mm Hg from absolute.
    8.2.2.11 Continue sweeping the remaining solvent VOC from the 
distillation flask and condenser assembly for 2 minutes, or until all 
traces of condensed solvent are gone from the vessel. Some distillate 
may remain in the still head. This will not affect solvent recovery 
ratios.
    8.2.2.12 Release the vacuum, disassemble the apparatus and transfer 
the distillate to a labeled, sealed vial.
    8.2.3 Preparation of VOC standard bag sample.
    8.2.3.1 Assemble the bag sample generation system as shown in Figure 
204F-2 and bring the water bath up to near boiling temperature.
    8.2.3.2 Inflate the Tedlar bag and perform a leak check on the bag.
    8.2.3.3 Evacuate the bag and close the bag inlet valve.
    8.2.3.4 Record the current barometric pressure.
    8.2.3.5 Record the starting reading on the dry gas meter, open the 
bag inlet valve, and start the dilution zero air flowing into the Tedlar 
bag at approximately 2 liters per minute.
    8.2.3.6 The bag sample VOC concentration should be similar to the 
gaseous VOC concentration measured in the gas streams. The amount of 
liquid VOC required can be approximated using equations in section 9.2. 
Using Equation 204F-4, calculate CVOC by assuming RF is 1.0 
and selecting the desired gas concentration in terms of propane, 
CC3.

[[Page 561]]

Assuming BV is 20 liters, ML, the approximate 
amount of liquid to be used to prepare the bag gas sample, can be 
calculated using Equation 204F-2.
    8.2.3.7 Quickly withdraw an aliquot of the approximate amount 
calculated in section 8.2.3.6 from the distillate vial with the 
microliter syringe and record its weight from the analytical balance to 
the nearest 0.01 mg.
    8.2.3.8 Inject the contents of the syringe through the septum of the 
volatilization vessel into the glass wool inside the vessel.
    8.2.3.9 Reweigh and record the tare weight of the now empty syringe.
    8.2.3.10 Record the pressure and temperature of the dilution gas as 
it is passed through the dry gas meter.
    8.2.3.11 After approximately 20 liters of dilution gas have passed 
into the Tedlar bag, close the valve to the dilution air source and 
record the exact final reading on the dry gas meter.
    8.2.3.12 The gas bag is then analyzed by FIA within 1 hour of bag 
preparation in accordance with the procedure in section 8.2.4.
    8.2.4 Determination of VOC response factor.
    8.2.4.1 Start up the FIA instrument using the same settings as used 
for the gaseous VOC measurements.
    8.2.4.2 Perform the FIA analyzer calibration and linearity checks 
according to the procedure in section 7.1. Record the responses to each 
of the calibration gases and the back-pressure setting of the FIA.
    8.2.4.3 Connect the Tedlar bag sample to the FIA sample inlet and 
record the bag concentration in terms of propane. Continue the analyses 
until a steady reading is obtained for at least 30 seconds. Record the 
final reading and calculate the RF.
    8.2.5 Determination of coating VOC content as VOC (VIJ).
    8.2.5.1 Determine the VOC content of the coatings used in the 
process using EPA Method 24 or 24A as applicable.

                    9. Data Analysis and Calculations

    9.1. Nomenclature.
BV = Volume of bag sample volume, liters.
CC3 = Concentration of bag sample as propane, mg/liter.
CVOC = Concentration of bag sample as VOC, mg/liter.
K = 0.00183 mg propane/(liter-ppm propane)
L = Total VOC content of liquid input, kg propane.
ML = Mass of VOC liquid injected into the bag, mg.
MV = Volume of gas measured by DGM, liters.
PM = Absolute DGM gas pressure, mm Hg.
PSTD = Standard absolute pressure, 760 mm Hg.
RC3 = FIA reading for bag gas sample, ppm propane.
RF = Response factor for VOC in liquid, weight VOC/weight propane.
RFJ = Response factor for VOC in liquid J, weight VOC/weight 
          propane.
TM = DGM temperature, [deg]K.
TSTD = Standard absolute temperature, 293 [deg]K.
VIJ = Initial VOC weight fraction of VOC liquid J.
VFJ = Final VOC weight fraction of VOC liquid J.
VAJ = VOC weight fraction of VOC liquid J added during the 
          run.
WIJ = Weight of VOC containing liquid J at beginning of run, 
          kg.
WFJ = Weight of VOC containing liquid J at end of run, kg.
WAJ = Weight of VOC containing liquid J added during the run, 
          kg.
    9.2 Calculations.
    9.2.1 Bag sample volume.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.021
    
    9.2.2 Bag sample VOC concentration.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.022
    
    9.2.3 Bag sample VOC concentration as propane.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.023
    
    9.2.4 Response Factor.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.024
    
    9.2.5 Total VOC Content of the Input VOC Containing Liquid.
    [GRAPHIC] [TIFF OMITTED] TR16JN97.025
    
                              10. Diagrams

      

[[Page 562]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.034


[[Page 563]]


[GRAPHIC] [TIFF OMITTED] TR16JN97.035


[[Page 564]]



 Method 205--Verification of Gas Dilution Systems for Field Instrument 
                              Calibrations

                             1. Introduction

    1.1 Applicability. A gas dilution system can provide known values of 
calibration gases through controlled dilution of high-level calibration 
gases with an appropriate dilution gas. The instrumental test methods in 
40 CFR part 60--e.g., Methods 3A, 6C, 7E, 10, 15, 16, 20, 25A and 25B--
require on-site, multi-point calibration using gases of known 
concentrations. A gas dilution system that produces known low-level 
calibration gases from high-level calibration gases, with a degree of 
confidence similar to that for Protocol \1\ gases, may be used for 
compliance tests in lieu of multiple calibration gases when the gas 
dilution system is demonstrated to meet the requirements of this method. 
The Administrator may also use a gas dilution system in order to produce 
a wide range of Cylinder Gas Audit concentrations when conducting 
performance specifications according to appendix F, 40 CFR part 60. As 
long as the acceptance criteria of this method are met, this method is 
applicable to gas dilution systems using any type of dilution 
technology, not solely the ones mentioned in this method.
    1.2 Principle. The gas dilution system shall be evaluated on one 
analyzer once during each field test. A precalibrated analyzer is 
chosen, at the discretion of the source owner or operator, to 
demonstrate that the gas dilution system produces predictable gas 
concentrations spanning a range of concentrations. After meeting the 
requirements of this method, the remaining analyzers may be calibrated 
with the dilution system in accordance to the requirements of the 
applicable method for the duration of the field test. In Methods 15 and 
16, 40 CFR part 60, appendix A, reactive compounds may be lost in the 
gas dilution system. Also, in Methods 25A and 25B, 40 CFR part 60, 
appendix A, calibration with target compounds other than propane is 
allowed. In these cases, a laboratory evaluation is required once per 
year in order to assure the Administrator that the system will dilute 
these reactive gases without significant loss.

    Note: The laboratory evaluation is required only if the source owner 
or operator plans to utilize the dilution system to prepare gases 
mentioned above as being reactive.

                            2. Specifications

    2.1 Gas Dilution System. The gas dilution system shall produce 
calibration gases whose measured values are within 2 percent of the predicted values. The predicted values 
are calculated based on the certified concentration of the supply gas 
(Protocol gases, when available, are recommended for their accuracy) and 
the gas flow rates (or dilution ratios) through the gas dilution system.
    2.1.1 The gas dilution system shall be recalibrated once per 
calendar year using NIST-traceable flow standards with an uncertainty 
<=0.25 percent. You shall report the results of the calibration by the 
person or manufacturer who carried out the calibration whenever the 
dilution system is used, listing the date of the most recent 
calibration, the due date for the next calibration, calibration point, 
reference flow device (ID, S/N), and acceptance criteria. Follow the 
manufacturer's instructions for the operation and use of the gas 
dilution system. A copy of the manufacturer's instructions for the 
operation of the instrument, as well as the most recent calibration 
documentation, shall be made available for inspection at the test site.
    2.1.2 Some manufacturers of mass flow controllers recommend that 
flow rates below 10 percent of flow controller capacity be avoided; 
check for this recommendation and follow the manufacturer's 
instructions. One study has indicated that silicone oil from a positive 
displacement pump produces an interference in SO2 analyzers 
utilizing ultraviolet fluorescence; follow laboratory procedures similar 
to those outlined in Section 3.1 in order to demonstrate the 
significance of any resulting effect on instrument performance.
    2.2 High-Level Supply Gas. An EPA Protocol calibration gas is 
recommended, due to its accuracy, as the high-level supply gas.
    2.3 Mid-Level Supply Gas. An EPA Protocol gas shall be used as an 
independent check of the dilution system. The concentration of the mid-
level supply gas shall be within 10 percent of one of the dilution 
levels tested in Section 3.2.

                          3. Performance Tests

    3.1 Laboratory Evaluation (Optional). If the gas dilution system is 
to be used to formulate calibration gases with reactive compounds (Test 
Methods 15, 16, and 25A/25B (only if using a calibration gas other than 
propane during the field test) in 40 CFR part 60, appendix A), a 
laboratory certification must be conducted once per calendar year for 
each reactive compound to be diluted. In the laboratory, carry out the 
procedures in Section 3.2 on the analyzer required in each respective 
test method to be laboratory certified (15, 16, or 25A and 25B for 
compounds other than propane). For each compound in which the gas 
dilution system meets the requirements in Section 3.2, the source must 
provide the laboratory certification data for the field test and in the 
test report.
    3.2 Field Evaluation (Required). The gas dilution system shall be 
evaluated at the test site with an analyzer or monitor chosen by

[[Page 565]]

the source owner or operator. It is recommended that the source owner or 
operator choose a precalibrated instrument with a high level of 
precision and accuracy for the purposes of this test. This method is not 
meant to replace the calibration requirements of test methods. In 
addition to the requirements in this method, all the calibration 
requirements of the applicable test method must also be met.
    3.2.1 Prepare the gas dilution system according to the 
manufacturer's instructions. Using the high-level supply gas, prepare, 
at a minimum, two dilutions within the range of each dilution device 
utilized in the dilution system (unless, as in critical orifice systems, 
each dilution device is used to make only one dilution; in that case, 
prepare one dilution for each dilution device). Dilution device in this 
method refers to each mass flow controller, critical orifice, capillary 
tube, positive displacement pump, or any other device which is used to 
achieve gas dilution.
    3.2.2 Calculate the predicted concentration for each of the 
dilutions based on the flow rates through the gas dilution system (or 
the dilution ratios) and the certified concentration of the high-level 
supply gas.
    3.2.3 Introduce each of the dilutions from Section 3.2.1 into the 
analyzer or monitor one at a time and determine the instrument response 
for each of the dilutions.
    3.2.4 Repeat the procedure in Section 3.2.3 two times, i.e., until 
three injections are made at each dilution level. Calculate the average 
instrument response for each triplicate injection at each dilution 
level. No single injection shall differ by more than 2 percent from the average instrument response for that 
dilution.
    3.2.5 For each level of dilution, calculate the difference between 
the average concentration output recorded by the analyzer and the 
predicted concentration calculated in Section 3.2.2. The average 
concentration output from the analyzer shall be within 2 percent of the predicted value.
    3.2.6 Introduce the mid-level supply gas directly into the analyzer, 
bypassing the gas dilution system. Repeat the procedure twice more, for 
a total of three mid-level supply gas injections. Calculate the average 
analyzer output concentration for the mid-level supply gas. The 
difference between the certified concentration of the mid-level supply 
gas and the average instrument response shall be within 2 percent.
    3.3 If the gas dilution system meets the criteria listed in Section 
3.2, the gas dilution system may be used throughout that field test. If 
the gas dilution system fails any of the criteria listed in Section 3.2, 
and the tester corrects the problem with the gas dilution system, the 
procedure in Section 3.2 must be repeated in its entirety and all the 
criteria in Section 3.2 must be met in order for the gas dilution system 
to be utilized in the test.

                              4. References

    1. ``EPA Traceability Protocol for Assay and Certification of 
Gaseous Calibration Standards,'' EPA-600/R93/224, Revised September 
1993.

Method 207--Pre-survey Procedure for Corn Wet-milling Facility Emission 
                                 Sources

                        1.0 Scope and Application

    1.1 Analyte. Total gaseous organic compounds.
    1.2 Applicability. This pre-survey method is intended for use at 
corn wet-milling (CWM) facilities to satisfy the requirements of Method 
18, Section 16 (Pre-survey). This procedure establishes the analytes for 
subsequent Method 18 testing to determine the total mass emissions of 
VOCs from sources at CWM facilities. The specific objectives of the pre-
survey procedure are:
    1.2.1 Identify the physical characteristics of the VOC contained in 
the effluent.
    1.2.2 Determine the appropriate Method 18 sampling approach to 
ensure efficient collection of all VOC present in the effluent.
    1.2.3 Develop a specific list of target compounds to be quantified 
during the subsequent total VOC test program.
    1.2.4 Qualify the list of target compounds as being a true 
representation of the total VOC.
    1.3 Range. The lower and upper ranges of this procedure are 
determined by the sensitivity of the flame ionization detector (FID) 
instruments used. Typically, gas detection limits for the VOCs will be 
on the order of 1-5 ppmv, with the upper limit on the order of 100,000 
ppmv.

                          2.0 Summary of Method

    Note: Method 6, Method 18, and Method 25A as cited in this method 
refer to the methods in 40 CFR Part 60, Appendix A.
    This procedure calls for using an FIA in conjunction with various 
configurations of impingers, and other absorbents, or adsorbents to 
determine the best EPA Method 18 sampling train configuration for the 
assessment and capture of VOCs. VOC compounds present in the exhaust gas 
from processes located at CWM facilities fall into five general 
categories: Alcohols, aldehydes, acetate esters, ketones, and carboxylic 
acids, and typically contain fewer than six carbon atoms. This pre-
survey protocol characterizes and identifies the VOC species present. 
Since it is qualitative in nature, quantitative performance criteria do 
not apply.

[[Page 566]]

                             3.0 Definitions

    3.1 Calibration drift means the difference in the measurement system 
response to a mid-level calibration gas before and after a stated period 
of operation during which no unscheduled maintenance, repair, or 
adjustment took place.
    3.2 Calibration error means the difference between the gas 
concentration indicated by the measurement system and the known 
concentration of the calibration gas.
    3.3 Calibration gas means a known concentration of a gas in an 
appropriate diluent gas.
    3.4 Measurement system means the equipment required for the 
determination of the gas concentration. The system consists of the 
following major subsystems:
    3.4.1 Sample interface means that portion of a system used for one 
or more of the following: Sample acquisition, sample transportation, 
sample conditioning, or protection of the analyzer(s) from the effects 
of the stack effluent.
    3.4.2 Organic analyzer means that portion of the measurement system 
that senses the gas to be measured and generates an output proportional 
to its concentration.
    3.5 Response time means the time interval from a step change in 
pollutant concentration at the inlet to the emission measurement system 
to the time at which 95 percent of the corresponding final value is 
reached as displayed on the recorder.
    3.6 Span Value means the upper limit of a gas concentration 
measurement range that is specified for affected source categories in 
the applicable part of the regulations. The span value is established in 
the applicable regulation and is usually 1.5 to 2.5 times the applicable 
emission limit. If no span value is provided, use a span value 
equivalent to 1.5 to 2.5 times the expected concentration. For 
convenience, the span value should correspond to 100 percent of the 
recorder scale.
    3.7 Zero drift means the difference in the measurement system 
response to a zero level calibration gas before or after a stated period 
of operation during which no unscheduled maintenance, repair, or 
adjustment took place.

                      4.0 Interferences [Reserved]

                          5.0 Safety [Reserved]

                       6.0 Equipment and Supplies

    6.1 Organic Concentration Analyzer. A flame ionization analyzer 
(FIA) with heated detector block and sample handling system, meeting the 
requirements of USEPA Method 25A.
    6.2 Heated Sampling System. A sampling system consisting of a 
stainless steel probe with particulate filter, Teflon [supreg] sample 
line, and sampling pump capable of moving 1.0 l/min through the sample 
probe and line. The entire system from probe tip to FIA analyzer must 
have the capability to maintain all sample-wetted parts at a temperature 
120 [deg]C. A schematic of the heated sampling system and 
impinger train is shown in Figure 1 of this method.
    6.3 Impinger Train. EPA Method 6 type, comprised of three midget 
impingers with appropriate connections to the sampling system and FIA 
system. The impinger train may be chilled in an ice bath or maintained 
at a set temperature in a water bath as indicated by the operator's 
knowledge of the source and the compounds likely to be present. 
Additional impingers or larger impingers may be used for high moisture 
sources.
    6.4 Adsorbent tubes.
    6.4.1 Silica gel, SKC Type 226-22 or equivalent, with appropriate 
end connectors and holders.
    6.4.2 Activated carbon, SKC Type 226-84 or equivalent, with 
appropriate end connectors and holders.
    6.5 Tedlar bag. 24 liter, w/ Roberts valve, for GC/MS analysis of 
``breakthrough'' VOC fraction as needed.

                       7.0 Reagents and Standards

    7.1 Organic-free water, HPLC, or pharmaceutical grade.
    7.2 Calibration Gases. The calibration gases for the gas analyzer 
shall be propane in air or propane in nitrogen. If organic compounds 
other than propane are used, the appropriate corrections for response 
factor must be available and applied to the results. Calibration gases 
shall be prepared in accordance with the procedure listed in Citation 2 
of section 16. Additionally, the manufacturer of the cylinder must 
provide a recommended shelf life for each calibration gas cylinder over 
which the concentration does not change more than 2 percent from the certified value. For calibration gas 
values not generally available (i.e., organics between 1 and 10 percent 
by volume), alternative methods for preparing calibration gas mixtures, 
such as dilution systems (Test Method 205, 40 CFR Part 51, Appendix M), 
may be used with prior approval of the Administrator.
    7.3 Fuel. A 40 percent H2/60 percent N2 or He gas mixture is 
recommended to avoid an oxygen synergism effect that reportedly occurs 
when oxygen concentration varies significantly from a mean value.
    7.4 Zero Gas. High purity air with less than 0.1 parts per million 
by volume (ppmv) of organic material (propane or carbon equivalent) or 
less than 0.1 percent of the span value, whichever is greater.
    7.5 Low-level Calibration Gas. An organic calibration gas with a 
concentration equivalent to 25 to 35 percent of the applicable span 
value.

[[Page 567]]

    7.6 Mid-level Calibration Gas. An organic calibration gas with a 
concentration equivalent to 45 to 55 percent of the applicable span 
value.
    7.7 High-level Calibration Gas. An organic calibration gas with a 
concentration equivalent to 80 to 90 percent of the applicable span 
value.

             8.0 Sample Collection, Preservation and Storage

    8.1 Configuration. The configuration of the pre-survey sampling 
system is provided in Figure 1. This figure shows the primary components 
of the sampling system needed to conduct a VOC survey. A dual-channel 
analyzer is beneficial, but not necessary. Only a single channel is 
indicated in the figure.
    8.2 Sampling. The pre-survey system should be set up and calibrated 
with the targeted sampling flow rate that will be used during Method 18 
VOC sampling. The targeted flow rate for capture of most expected VOC 
species is 400 cc/min. Since most FIA analyzers do not specifically 
allow for adjusting the total sample flow rate (only the back pressure), 
it may be necessary to insert a flow control valve at the sample inlet 
to the FIA. The total sample flow can be measured at the FIA bypass, 
since only a small fraction of the sample flow is diverted to analysis 
portion of the instrument.
    The sampling system configuration shown in Figure 1 is operated 
using the process flow diagram provided in Figure 2. As noted in the 
process flowchart, the initial sampling media consists of the three 
midget impingers. The attenuation of the VOC sample stream is evaluated 
to determine if 95 percent or greater attenuation (capture) of the VOCs 
present has been achieved. The flow diagram specifies successive 
adjustments to the sampling media that are utilized to increase VOC 
capture.
    A one-hour test of the final sampling configuration is performed 
using fresh media to ensure that significant breakthrough does not 
occur. Additional sampling media (more water, silica or carbon tubes) 
may be added to ensure that breakthrough is not occurring for the full 
duration of a test run.
    If 95 percent or greater attenuation has not been achieved after 
inserting all indicated media, the most likely scenario is that methane 
is present. This is easily checked by collecting a sample of this final 
bypass sample stream and analyzing for methane. There are other VOC 
compounds which could also penetrate the media. Their identification by 
gas chromatography followed by mass spectrometry would be required if 
the breakthrough cannot be accounted for by the presence of methane.

                           9.0 Quality Control

    9.1 Blanks. A minimum of one method blank shall be prepared and 
analyzed for each sample medium employed during a pre-survey testing 
field deployment to assess the effect of media contamination. Method 
blanks are prepared by assembling and charging the sample train with 
reagents, then recovering and preserving the blanks in the same manner 
as the test samples. Method blanks and test samples are stored, 
transported and analyzed in identical fashion as the test samples.
    9.2 Synthetic Sample (optional). A synthetic sample may be used to 
assess the performance of the VOC characterization apparatus with 
respect to specific compounds. The synthetic sample is prepared by 
injecting appropriate volume(s) of the compounds of interest into a 
Tedlar bag containing a known volume of zero air or nitrogen. The 
contents of the bag are allowed to equilibrate, and the bag is connected 
to the sampling system. The sampling system, VOC characterization 
apparatus and FIA are operated normally to determine the performance of 
the system with respect to the VOC compounds present in the synthetic 
sample.

                  10.0 Calibration and Standardization

    10.1 Calibration. The FIA equipment is able to be calibrated for 
almost any range of total organic concentrations. For high 
concentrations of organics (1.0 percent by volume as 
propane), modifications to most commonly available analyzers are 
necessary. One accepted method of equipment modification is to decrease 
the size of the sample to the analyzer through the use of a smaller 
diameter sample capillary. Direct and continuous measurement of organic 
concentration is a necessary consideration when determining any 
modification design.

                             11.0 Procedure

    11.1 Analytical Procedure. Upon completion of the pre-survey 
sampling, the sample fractions are to be analyzed by an appropriate 
chromatographic technique. (Ref: Method 18) The resulting chromatograms 
must be reviewed to ensure that the ratio of known peak area to total 
peak area is 95% or greater. It should be noted that if formaldehyde is 
a suspected analyte, it must be quantitated separately using a different 
analytical technique.

                   12.0 Data Analysis and Calculations

    Chromatogram peaks will be ranked from greatest area to least area 
using peak integrator output. The area of all peaks will then be 
totaled, and the proportion of each peak area to the total area will be 
calculated. Beginning with the highest ranked area, each peak will be 
identified and the

[[Page 568]]

area added to previous areas until the cumulative area comprises at 
least 95% of the total area. The VOC compounds generating those 
identified peaks will comprise the compound list to be used in Method 18 
testing of the subject source.

                   13.0 Method Performance [Reserved]

                  14.0 Pollution Prevention [Reserved]

                    15.0 Waste Management [Reserved]

                             16.0 References

    16.1 CFR 40 Part 60, Appendix A, Method 18, Measurement of Gaseous 
Organic Compound Emissions by Gas Chromatography.
    16.2 CFR 40 Part 60, Appendix A, Method 25A, Determination of Total 
Gaseous Organic Concentration Using a Flame Ionization Analyzer.
    16.2 CFR 40 Part 60, Appendix A, Method 6, Determination of Sulfur 
Dioxide Emissions from Stationary Sources.
    16.3 National Council for Air and Stream Improvement (NCASI), Method 
CI/WP-98.01 ``Chilled Impinger Method for Use at Wood Products Mills to 
Measure Formaldehyde, Methanol, and Phenol.

          17. Tables, Diagrams, Flowcharts, and Validation Data

[[Page 569]]

[GRAPHIC] [TIFF OMITTED] TR29MY08.000


[[Page 570]]


[GRAPHIC] [TIFF OMITTED] TR29MY08.001


[[Page 571]]



[55 FR 14249, Apr. 17, 1990; 55 FR 24687, June 18, 1990, as amended at 
55 FR 37606, Sept. 12, 1990; 56 FR 6278, Feb. 15, 1991; 56 FR 65435, 
Dec. 17, 1991; 60 FR 28054, May 30, 1995; 62 FR 32502, June 16, 1997; 71 
FR 55123, Sept. 21, 2006; 73 FR 30779, May 29, 2008; 75 FR 55644, Sept. 
13, 2010; 75 FR 80134, Dec. 21, 2010; 79 FR 11235, Feb. 27, 2014; 79 FR 
18453, Apr. 2, 2014; 81 FR 59806, Aug. 30, 2016; 83 FR 56720, Nov. 14, 
2018; 85 FR 63401, Oct. 7, 2020]



                Sec. Appendixes N-O to Part 51 [Reserved]



  Sec. Appendix P to Part 51--Minimum Emission Monitoring Requirements

    1.0 Purpose. This appendix P sets forth the minimum requirements for 
continuous emission monitoring and recording that each State 
Implementation Plan must include in order to be approved under the 
provisions of 40 CFR 51.214. These requirements include the source 
categories to be affected; emission monitoring, recording, and reporting 
requirements for those sources; performance specifications for accuracy, 
reliability, and durability of acceptable monitoring systems; and 
techniques to convert emission data to units of the applicable State 
emission standard. Such data must be reported to the State as an 
indication of whether proper maintenance and operating procedures are 
being utilized by source operators to maintain emission levels at or 
below emission standards. Such data may be used directly or indirectly 
for compliance determination or any other purpose deemed appropriate by 
the State. Though the monitoring requirements are specified in detail, 
States are given some flexibility to resolve difficulties that may arise 
during the implementation of these regulations.
    1.1 Applicability. The State plan shall require the owner or 
operator of an emission source in a category listed in this appendix to: 
(1) Install, calibrate, operate, and maintain all monitoring equipment 
necessary for continuously monitoring the pollutants specified in this 
appendix for the applicable source category; and (2) complete the 
installation and performance tests of such equipment and begin 
monitoring and recording within 18 months of plan approval or 
promulgation. The source categories and the respective monitoring 
requirements are listed below.
    1.1.1 Fossil fuel-fired steam generators, as specified in paragraph 
2.1 of this appendix, shall be monitored for opacity, nitrogen oxides 
emissions, sulfur dioxide emissions, and oxygen or carbon dioxide.
    1.1.2 Fluid bed catalytic cracking unit catalyst regenerators, as 
specified in paragraph 2.4 of this appendix, shall be monitored for 
opacity.
    1.1.3 Sulfuric acid plants, as specified in paragraph 2.3 of this 
appendix, shall be monitored for sulfur dioxide emissions.
    1.1.4 Nitric acid plants, as specified in paragraph 2.2 of this 
appendix, shall be monitored for nitrogen oxides emissions.
    1.2 Exemptions. The States may include provisions within their 
regulations to grant exemptions from the monitoring requirements of 
paragraph 1.1 of this appendix for any source which is:
    1.2.1 Subject to a new source performance standard promulgated in 40 
CFR part 60 pursuant to section 111 of the Clean Air Act; or
    1.2.2 not subject to an applicable emission standard of an approved 
plan; or
    1.2.3 scheduled for retirement within 5 years after inclusion of 
monitoring requirements for the source in appendix P, provided that 
adequate evidence and guarantees are provided that clearly show that the 
source will cease operations prior to such date.
    1.3 Extensions. States may allow reasonable extensions of the time 
provided for installation of monitors for facilities unable to meet the 
prescribed timeframe (i.e., 18 months from plan approval or 
promulgation) provided the owner or operator of such facility 
demonstrates that good faith efforts have been made to obtain and 
install such devices within such prescribed timeframe.
    1.4 Monitoring System Malfunction. The State plan may provide a 
temporary exemption from the monitoring and reporting requirements of 
this appendix during any period of monitoring system malfunction, 
provided that the source owner or operator shows, to the satisfaction of 
the State, that the malfunction was unavoidable and is being repaired as 
expeditiously as practicable.
    2.0 Minimum Monitoring Requirement. States must, as a minimum, 
require the sources listed in paragraph 1.1 of this appendix to meet the 
following basic requirements.
    2.1 Fossil fuel-fired steam generators. Each fossil fuel-fired steam 
generator, except as provided in the following subparagraphs, with an 
annual average capacity factor of greater than 30 percent, as reported 
to the Federal Power Commission for calendar year 1974, or as otherwise 
demonstrated to the State by the owner or operator, shall conform with 
the following monitoring requirements when such facility is subject to 
an emission standard of an applicable plan for the pollutant in 
question.
    2.1.1 A continuous monitoring system for the measurement of opacity 
which meets the performance specifications of paragraph 3.1.1 of this 
appendix shall be installed, calibrated, maintained, and operated in 
accordance with the procedures of this appendix by the owner or operator 
of any such steam generator of greater than 250 million BTU per hour 
heat input except where:

[[Page 572]]

    2.1.1.1 gaseous fuel is the only fuel burned, or
    2.1.1.2 oil or a mixture of gas and oil are the only fuels burned 
and the source is able to comply with the applicable particulate matter 
and opacity regulations without utilization of particulate matter 
collection equipment, and where the source has never been found, through 
any administrative or judicial proceedings, to be in violation of any 
visible emission standard of the applicable plan.
    2.1.2 A continuous monitoring system for the measurement of sulfur 
dioxide which meets the performance specifications of paragraph 3.1.3 of 
this appendix shall be installed, calibrated, maintained, and operated 
on any fossil fuel-fired steam generator of greater than 250 million BTU 
per hour heat input which has installed sulfur dioxide pollutant control 
equipment.
    2.1.3 A continuous monitoring system for the measurement of nitrogen 
oxides which meets the performance specification of paragraph 3.1.2 of 
this appendix shall be installed, calibrated, maintained, and operated 
on fossil fuel-fired steam generators of greater than 1000 million BTU 
per hour heat input when such facility is located in an Air Quality 
Control Region where the Administrator has specifically determined that 
a control strategy for nitrogen dioxide is necessary to attain the 
national standards, unless the source owner or operator demonstrates 
during source compliance tests as required by the State that such a 
source emits nitrogen oxides at levels 30 percent or more below the 
emission standard within the applicable plan.
    2.1.4 A continuous monitoring system for the measurement of the 
percent oxygen or carbon dioxide which meets the performance 
specifications of paragraphs 3.1.4 or 3.1.5 of this appendix shall be 
installed, calibrated, operated, and maintained on fossil fuel-fired 
steam generators where measurements of oxygen or carbon dioxide in the 
flue gas are required to convert either sulfur dioxide or nitrogen 
oxides continuous emission monitoring data, or both, to units of the 
emission standard within the applicable plan.
    2.2 Nitric acid plants. Each nitric acid plant of greater than 300 
tons per day production capacity, the production capacity being 
expressed as 100 percent acid, located in an Air Quality Control Region 
where the Administrator has specifically determined that a control 
strategy for nitrogen dioxide is necessary to attain the national 
standard shall install, calibrate, maintain, and operate a continuous 
monitoring system for the measurement of nitrogen oxides which meets the 
performance specifications of paragraph 3.1.2 for each nitric acid 
producing facility within such plant.
    2.3 Sulfuric acid plants. Each Sulfuric acid plant of greater than 
300 tons per day production capacity, the production being expressed as 
100 percent acid, shall install, calibrate, maintain and operate a 
continuous monitoring system for the measurement of sulfur dioxide which 
meets the performance specifications of paragraph 3.1.3 for each 
sulfuric acid producing facility within such plant.
    2.4 Fluid bed catalytic cracking unit catalyst regenerators at 
petroleum refineries. Each catalyst regenerator for fluid bed catalytic 
cracking units of greater than 20,000 barrels per day fresh feed 
capacity shall install, calibrate, maintain, and operate a continuous 
monitoring system for the measurement of opacity which meets the 
performance specifications of paragraph 3.1.1.
    3.0 Minimum specifications. All State plans shall require owners or 
operators of monitoring equipment installed to comply with this 
appendix, except as provided in paragraph 3.2, to demonstrate compliance 
with the following performance specifications.
    3.1 Performance specifications. The performance specifications set 
forth in appendix B of part 60 are incorporated herein by reference, and 
shall be used by States to determine acceptability of monitoring 
equipment installed pursuant to this appendix except that (1) where 
reference is made to the ``Administrator'' in appendix B, part 60, the 
term State should be inserted for the purpose of this appendix (e.g., in 
Performance Specification 1, 1.2, `` * * * monitoring systems subject to 
approval by the Administrator,'' should be interpreted as, ``* * * 
monitoring systems subject to approval by the State''), and (2) where 
reference is made to the ``Reference Method'' in appendix B, part 60, 
the State may allow the use of either the State approved reference 
method or the Federally approved reference method as published in part 
60 of this chapter. The Performance Specifications to be used with each 
type of monitoring system are listed below.
    3.1.1 Continuous monitoring systems for measuring opacity shall 
comply with Performance Specification 1.
    3.1.2 Continuous monitoring systems for measuring nitrogen oxides 
shall comply with Performance Specification 2.
    3.1.3 Continuous monitoring systems for measuring sulfur dioxide 
shall comply with Performance Specification 2.
    3.1.4 Continuous monitoring systems for measuring oxygen shall 
comply with Performance Specification 3.
    3.1.5 Continuous monitoring systems for measuring carbon dioxide 
shall comply with Performance Specification 3.
    3.2 Exemptions. Any source which has purchased an emission 
monitoring system(s) prior to September 11, 1974, may be exempt from 
meeting such test procedures prescribed in appendix B of part 60 for a 
period not to exceed five years from plan approval or promulgation.

[[Page 573]]

    3.3 Calibration Gases. For nitrogen oxides monitoring systems 
installed on fossil fuel-fired steam generators, the pollutant gas used 
to prepare calibration gas mixtures (section 6.1, Performance 
Specification 2, appendix B, part 60 of this chapter) shall be nitric 
oxide (NO). For nitrogen oxides monitoring systems installed on nitric 
acid plants, the pollutant gas used to prepare calibration gas mixtures 
(section 6.1, Performance Specification 2, appendix B, part 60 of this 
chapter) shall be nitrogen dioxide (NO2). These gases shall 
also be used for daily checks under paragraph 3.7 of this appendix as 
applicable. For sulfur dioxide monitoring systems installed on fossil 
fuel-fired steam generators or sulfuric acid plants, the pollutant gas 
used to prepare calibration gas mixtures (section 6.1, Performance 
Specification 2, appendix B, part 60 of this chapter) shall be sulfur 
dioxide (SO2). Span and zero gases should be traceable to 
National Bureau of Standards reference gases whenever these reference 
gases are available. Every 6 months from date of manufacture, span and 
zero gases shall be reanalyzed by conducting triplicate analyses using 
the reference methods in appendix A, part 60 of this chapter as follows: 
for SO2, use Reference Method 6; for nitrogen oxides, use 
Reference Method 7; and for carbon dioxide or oxygen, use Reference 
Method 3. The gases may be analyzed at less frequent intervals if longer 
shelf lives are guaranteed by the manufacturer.
    3.4 Cycling times. Cycling times include the total time a monitoring 
system requires to sample, analyze and record an emission measurement.
    3.4.1 Continuous monitoring systems for measuring opacity shall 
complete a minimum of one cycle of operation (sampling, analyzing, and 
data recording) for each successive 10-second period.
    3.4.2 Continuous monitoring systems for measuring oxides of 
nitrogen, carbon dioxide, oxygen, or sulfur dioxide shall complete a 
minimum of one cycle of operation (sampling, analyzing, and data 
recording) for each successive 15-minute period.
    3.5 Monitor location. State plans shall require all continuous 
monitoring systems or monitoring devices to be installed such that 
representative measurements of emissions or process parameters (i.e., 
oxygen, or carbon dioxide) from the affected facility are obtained. 
Additional guidance for location of continuous monitoring systems to 
obtain representative samples are contained in the applicable 
Performance Specifications of appendix B of part 60 of this chapter.
    3.6 Combined effluents. When the effluents from two or more affected 
facilities of similar design and operating characteristics are combined 
before being released to the atmosphere, the State plan may allow 
monitoring systems to be installed on the combined effluent. When the 
affected facilities are not of similar design and operating 
characteristics, or when the effluent from one affected facility is 
released to the atmosphere through more than one point, the State should 
establish alternate procedures to implement the intent of these 
requirements.
    3.7 Zero and drift. State plans shall require owners or operators of 
all continuous monitoring systems installed in accordance with the 
requirements of this appendix to record the zero and span drift in 
accordance with the method prescribed by the manufacturer of such 
instruments; to subject the instruments to the manufacturer's 
recommended zero and span check at least once daily unless the 
manufacturer has recommended adjustments at shorter intervals, in which 
case such recommendations shall be followed; to adjust the zero and span 
whenever the 24-hour zero drift or 24-hour calibration drift limits of 
the applicable performance specifications in appendix B of part 60 are 
exceeded; and to adjust continuous monitoring systems referenced by 
paragraph 3.2 of this appendix whenever the 24-hour zero drift or 24-
hour calibration drift exceed 10 percent of the emission standard.
    3.8 Span. Instrument span should be approximately 200 per cent of 
the expected instrument data display output corresponding to the 
emission standard for the source.
    3.9 Alternative procedures and requirements. In cases where States 
wish to utilize different, but equivalent, procedures and requirements 
for continuous monitoring systems, the State plan must provide a 
description of such alternative procedures for approval by the 
Administrator. Some examples of situations that may require alternatives 
follow:
    3.9.1 Alternative monitoring requirements to accommodate continuous 
monitoring systems that require corrections for stack moisture 
conditions (e.g., an instrument measuring steam generator SO2 
emissions on a wet basis could be used with an instrument measuring 
oxygen concentration on a dry basis if acceptable methods of measuring 
stack moisture conditions are used to allow accurate adjustments of the 
measured SO2 concentration to dry basis.)
    3.9.2 Alternative locations for installing continuous monitoring 
systems or monitoring devices when the owner or operator can demonstrate 
that installation at alternative locations will enable accurate and 
representative measurements.
    3.9.3 Alternative procedures for performing calibration checks 
(e.g., some instruments may demonstrate superior drift characteristics 
that require checking at less frequent intervals).
    3.9.4 Alternative monitoring requirements when the effluent from one 
affected facility or the combined effluent from two or more identical 
affected facilities is released to the atmosphere through more than one 
point

[[Page 574]]

(e.g., an extractive, gaseous monitoring system used at several points 
may be approved if the procedures recommended are suitable for 
generating accurate emission averages).
    3.9.5 Alternative continuous monitoring systems that do not meet the 
spectral response requirements in Performance Specification 1, appendix 
B of part 60, but adequately demonstrate a definite and consistent 
relationship between their measurements and the opacity measurements of 
a system complying with the requirements in Performance Specification 1. 
The State may require that such demonstration be performed for each 
affected facility.
    4.0 Minimum data requirements. The following paragraphs set forth 
the minimum data reporting requirements necessary to comply with Sec. 
51.214(d) and (e).
    4.1 The State plan shall require owners or operators of facilities 
required to install continuous monitoring systems to submit a written 
report of excess emissions twice per year at 6-month intervals and the 
nature and cause of the excess emissions, if known. The averaging period 
used for data reporting should be established by the State to correspond 
to the averaging period specified in the emission test method used to 
determine compliance with an emission standard for the pollutant/source 
category in question. The required report shall include, as a minimum, 
the data stipulated in this appendix.
    4.2 For opacity measurements, the summary shall consist of the 
magnitude in actual percent opacity of all one-minute (or such other 
time period deemed appropriate by the State) averages of opacity greater 
than the opacity standard in the applicable plan for each hour of 
operation of the facility. Average values may be obtained by integration 
over the averaging period or by arithmetically averaging a minimum of 
four equally spaced, instantaneous opacity measurements per minute. Any 
time period exempted shall be considered before determining the excess 
averages of opacity (e.g., whenever a regulation allows two minutes of 
opacity measurements in excess of the standard, the State shall require 
the source to report all opacity averages, in any one hour, in excess of 
the standard, minus the two-minute exemption). If more than one opacity 
standard applies, excess emissions data must be submitted in relation to 
all such standards.
    4.3 For gaseous measurements the summary shall consist of emission 
averages, in the units of the applicable standard, for each averaging 
period during which the applicable standard was exceeded.
    4.4 The date and time identifying each period during which the 
continuous monitoring system was inoperative, except for zero and span 
checks, and the nature of system repairs or adjustments shall be 
reported. The State may require proof of continuous monitoring system 
performance whenever system repairs or adjustments have been made.
    4.5 When no excess emissions have occurred and the continuous 
monitoring system(s) have not been inoperative, repaired, or adjusted, 
such information shall be included in the report.
    4.6 The State plan shall require owners or operators of affected 
facilities to maintain a file of all information reported as specified 
in paragraph 4.1 of this appendix, all other data collected either by 
the continuous monitoring system or as necessary to convert monitoring 
data to the units of the applicable standard for a minimum of two years 
from the date of collection of such data or submission of such 
summaries.
    5.0 Data Reduction. The State plan shall require owners or operators 
of affected facilities to use the following procedures for converting 
monitoring data to units of the standard where necessary.
    5.1 For fossil fuel-fired steam generators the following procedures 
shall be used to convert gaseous emission monitoring data in parts per 
million to g/million cal (lb/million BTU) where necessary:
    5.1.1 When the owner or operator of a fossil fuel-fired steam 
generator elects under paragraph 2.1.4 of this appendix to measure 
oxygen in the flue gases, the measurements of the pollutant 
concentration and oxygen concentration shall each be on a dry basis and 
the following conversion procedure used:

E = CF [20.9/20.9 - %O2]

    5.1.2 When the owner or operator elects under paragraph 2.1.4 of 
this appendix to measure carbon dioxide in the flue gases, the 
measurement of the pollutant concentration and the carbon dioxide 
concentration shall each be on a consistent basis (wet or dry) and the 
following conversion procedure used:

E = CFc (100 / %CO2)

    5.1.3 The values used in the equations under paragraph 5.1 are 
derived as follows:
    E = pollutant emission, g/million cal (lb/million BTU),
    C = pollutant concentration, g/dscm (lb/dscf), determined by 
multiplying the average concentration (ppm) for each hourly period by 
4.16 x 10-5 M g/dscm per ppm (2.64 x 10-9 M lb/
dscf per ppm) where M = pollutant molecular weight, g/g-mole (lb/lb-
mole). M = 64 for sulfur dioxide and 46 for oxides of nitrogen.
    %O2, %CO2 = Oxygen or carbon dioxide volume 
(expressed as percent) determined with equipment specified under 
paragraphs 3.1.4 and 3.1.5 of this appendix.

    5.2 For sulfuric acid plants the owner or operator shall:
    5.2.1 establish a conversion factor three times daily according to 
the procedures to Sec. 60.84(b) of this chapter;
    5.2.2 multiply the conversion factor by the average sulfur dioxide 
concentration in the

[[Page 575]]

flue gases to obtain average sulfur dioxide emissions in Kg/metric ton 
(lb/short ton); and
    5.2.3 report the average sulfur dioxide emission for each averaging 
period in excess of the applicable emission standard in the reports 
submitted as specified in paragraph 4.1 of this appendix.
    5.3 For nitric acid plants the owner or operator shall:
    5.3.1 establish a conversion factor according to the procedures of 
Sec. 60.73(b) of this chapter;
    5.3.2 multiply the conversion factor by the average nitrogen oxides 
concentration in the flue gases to obtain the nitrogen oxides emissions 
in the units of the applicable standard;
    5.3.3 report the average nitrogen oxides emission for each averaging 
period in excess of the applicable emission standard, in the reports 
submitted as specified in paragraph 4.1 of this appendix.
    5.4 Any State may allow data reporting or reduction procedures 
varying from those set forth in this appendix if the owner or operator 
of a source shows to the satisfaction of the State that his procedures 
are at least as accurate as those in this appendix. Such procedures may 
include but are not limited to, the following:
    5.4.1 Alternative procedures for computing emission averages that do 
not require integration of data (e.g., some facilities may demonstrate 
that the variability of their emissions is sufficiently small to allow 
accurate reduction of data based upon computing averages from equally 
spaced data points over the averaging period).
    5.4.2 Alternative methods of converting pollutant concentration 
measurements to the units of the emission standards.
    6.0 Special Consideration. The State plan may provide for approval, 
on a case-by-case basis, of alternative monitoring requirements 
different from the provisions of parts 1 through 5 of this appendix if 
the provisions of this appendix (i.e., the installation of a continuous 
emission monitoring system) cannot be implemented by a source due to 
physical plant limitations or extreme economic reasons. To make use of 
this provision, States must include in their plan specific criteria for 
determining those physical limitations or extreme economic situations to 
be considered by the State. In such cases, when the State exempts any 
source subject to this appendix by use of this provision from installing 
continuous emission monitoring systems, the State shall set forth 
alternative emission monitoring and reporting requirements (e.g., 
periodic manual stack tests) to satisfy the intent of these regulations. 
Examples of such special cases include, but are not limited to, the 
following:
    6.1 Alternative monitoring requirements may be prescribed when 
installation of a continuous monitoring system or monitoring device 
specified by this appendix would not provide accurate determinations of 
emissions (e.g., condensed, uncombined water vapor may prevent an 
accurate determination of opacity using commercially available 
continuous monitoring systems).
    6.2 Alternative monitoring requirements may be prescribed when the 
affected facility is infrequently operated (e.g., some affected 
facilities may operate less than one month per year).
    6.3 Alternative monitoring requirements may be prescribed when the 
State determines that the requirements of this appendix would impose an 
extreme economic burden on the source owner or operator.
    6.4 Alternative monitoring requirements may be prescribed when the 
State determines that monitoring systems prescribed by this appendix 
cannot be installed due to physical limitations at the facility.

[40 FR 46247, Oct. 6, 1975, as amended at 51 FR 40675, Nov. 7, 1986; 81 
FR 59808, Aug. 30, 2016; 85 FR 49600, Aug. 14, 2020]



                Sec. Appendixes Q-R to Part 51 [Reserved]



    Sec. Appendix S to Part 51--Emission Offset Interpretative Ruling

                             I. Introduction

    This appendix sets forth EPA's Interpretative Ruling on the 
preconstruction review requirements for stationary sources of air 
pollution (not including indirect sources) under 40 CFR subpart I and 
section 129 of the Clean Air Act Amendments of 1977, Public Law 95-95, 
(note under 42 U.S.C. 7502). A major new source or major modification 
which would locate in any area designated under section 107(d) of the 
Act as attainment or unclassifiable for ozone that is located in an 
ozone transport region or which would locate in an area designated in 40 
CFR part 81, subpart C, as nonattainment for a pollutant for which the 
source or modification would be major may be allowed to construct only 
if the stringent conditions set forth below are met. These conditions 
are designed to insure that the new source's emissions will be 
controlled to the greatest degree possible; that more than equivalent 
offsetting emission reductions (emission offsets) will be obtained from 
existing sources; and that there will be progress toward achievement of 
the NAAQS.
    For each area designated as exceeding a NAAQS (nonattainment area) 
under 40 CFR part 81, subpart C, or for any area designated under 
section 107(d) of the Act as attainment or unclassifiable for ozone that 
is located in an ozone transport region, this Interpretative Ruling will 
be superseded after June 30, 1979 (a) by preconstruction review 
provisions

[[Page 576]]

of the revised SIP, if the SIP meets the requirements of Part D, Title 
1, of the Act; or (b) by a prohibition on construction under the 
applicable SIP and section 110(a)(2)(I) of the Act, if the SIP does not 
meet the requirements of Part D. The Ruling will remain in effect to the 
extent not superseded under the Act. This prohibition on major new 
source construction does not apply to a source whose permit to construct 
was applied for during a period when the SIP was in compliance with Part 
D, or before the deadline for having a revised SIP in effect that 
satisfies Part D.
    The requirement of this Ruling shall not apply to any major 
stationary source or major modification that was not subject to the 
Ruling as in effect on January 16, 1979, if the owner or operator:
    A. Obtained all final Federal, State, and local preconstruction 
approvals or permits necessary under the applicable State Implementation 
Plan before August 7, 1980;
    B. Commenced construction within 18 months from August 7, 1980, or 
any earlier time required under the applicable State Implementation 
Plan; and
    C. Did not discontinue construction for a period of 18 months or 
more and completed construction within a reasonable time.

     II. Initial Screening Analyses and Determination of Applicable 
                              Requirements

    A. Definitions--For the purposes of this Ruling:
    1. Stationary source means any building, structure, facility, or 
installation which emits or may emit a regulated NSR pollutant.
    2. (i) Building, structure, facility or installation means all of 
the pollutant-emitting activities which belong to the same industrial 
grouping, are located on one or more contiguous or adjacent properties, 
and are under the control of the same person (or persons under common 
control) except the activities of any vessel. Pollutant-emitting 
activities shall be considered as part of the same industrial grouping 
if they belong to the same ``Major Group'' (i.e., which have the same 
two digit code) as described in the Standard Industrial Classification 
Manual, 1972, as amended by the 1977 Supplement (U.S. Government 
Printing Office stock numbers 4101-0066 and 003-005-00176-0, 
respectively).
    (ii) Notwithstanding the provisions of paragraph II.A.2(i) of this 
section, building, structure, facility or installation means, for 
onshore activities under SIC Major Group 13: Oil and Gas Extraction, all 
of the pollutant-emitting activities included in Major Group 13 that are 
located on one or more contiguous or adjacent properties, and are under 
the control of the same person (or persons under common control). 
Pollutant emitting activities shall be considered adjacent if they are 
located on the same surface site; or if they are located on surface 
sites that are located within \1/4\ mile of one another (measured from 
the center of the equipment on the surface site) and they share 
equipment. Shared equipment includes, but is not limited to, produced 
fluids storage tanks, phase separators, natural gas dehydrators or 
emissions control devices. Surface site, as used in this paragraph 
II.A.2(ii), has the same meaning as in 40 CFR 63.761.
    3. Potential to emit means the maximum capacity of a stationary 
source to emit a pollutant under its physical and operational design. 
Any physical or operational limitation on the capacity of the source to 
emit a pollutant, including air pollution control equipment and 
restrictions on hours of operation or on the type or amount of material 
combusted, stored, or processed, shall be treated as part of its design 
only if the limitation or the effect it would have on emissions is 
federally enforceable. Secondary emissions do not count in determining 
the potential to emit of a stationary source.
    4. (i) Major stationary source means:
    (a) Any stationary source of air pollutants which emits, or has the 
potential to emit, 100 tons per year or more of a regulated NSR 
pollutant (as defined in paragraph II.A.31 of this Ruling), except that 
lower emissions thresholds shall apply in areas subject to subpart 2, 
subpart 3, or subpart 4 of part D, title I of the Act, according to 
paragraphs II.A.4(i)(a)(1) through (8) of this ruling.
    (1) 50 tons per year of volatile organic compounds in any serious 
ozone nonattainment area.
    (2) 50 tons per year of volatile organic compounds in an area within 
an ozone transport region, except for any severe or extreme ozone 
nonattainment area.
    (3) 25 tons per year of volatile organic compounds in any severe 
ozone nonattainment area.
    (4) 10 tons per year of volatile organic compounds in any extreme 
ozone nonattainment area.
    (5) 50 tons per year of carbon monoxide in any serious nonattainment 
area for carbon monoxide, where stationary sources contribute 
significantly to carbon monoxide levels in the area (as determined under 
rules issued by the Administrator)
    (6) 70 tons per year of PM-10 in any serious nonattainment area for 
PM-10;
    (7) 70 tons per year of PM2.5 in any serious 
nonattainment area for PM2.5.
    (8) 70 tons per year of any individual PM2.5 precursor 
(as defined in paragraph II.A.31 of this Ruling) in any Serious 
nonattainment area for PM2.5.
    (b) For the purposes of applying the requirements of paragraph IV. H 
of this Ruling to stationary sources of nitrogen oxides located in an 
ozone nonattainment area or in an ozone transport region, any stationary 
source which emits, or has the potential to

[[Page 577]]

emit, 100 tons per year or more of nitrogen oxides emissions, except 
that the emission thresholds in paragraphs II.A.4(i)(b)(1) through (6) 
of this Ruling apply in areas subject to subpart 2 of part D, title I of 
the Act.
    (1) 100 tons per year or more of nitrogen oxides in any ozone 
nonattainment area classified as marginal or moderate.
    (2) 100 tons per year or more of nitrogen oxides in any ozone 
nonattainment area classified as a transitional, submarginal, or 
incomplete or no data area, when such area is located in an ozone 
transport region.
    (3) 100 tons per year or more of nitrogen oxides in any area 
designated under section 107(d) of the Act as attainment or 
unclassifiable for ozone that is located in an ozone transport region.
    (4) 50 tons per year or more of nitrogen oxides in any serious 
nonattainment area for ozone.
    (5) 25 tons per year or more of nitrogen oxides in any severe 
nonattainment area for ozone.
    (6) 10 tons per year or more of nitrogen oxides in any extreme 
nonattainment area for ozone; or
    (c) Any physical change that would occur at a stationary source not 
qualifying under paragraph II.A.4(i)(a) or (b) of this Ruling as a major 
stationary source, if the change would constitute a major stationary 
source by itself.
    (ii) A major stationary source that is major for volatile organic 
compounds or nitrogen oxides is major for ozone.
    (iii) The fugitive emissions of a stationary source shall not be 
included in determining for any of the purposes of this ruling whether 
it is a major stationary source, unless the source belongs to one of the 
following categories of stationary sources:
    (a) Coal cleaning plants (with thermal dryers);
    (b) Kraft pulp mills;
    (c) Portland cement plants;
    (d) Primary zinc smelters;
    (e) Iron and steel mills;
    (f) Primary aluminum ore reduction plants;
    (g) Primary copper smelters;
    (h) Municipal incinerators capable of charging more than 250 tons of 
refuse per day;
    (i) Hydrofluoric, sulfuric, or nitric acid plants;
    (j) Petroleum refineries;
    (k) Lime plants;
    (l) Phosphate rock processing plants;
    (m) Coke oven batteries;
    (n) Sulfur recovery plants;
    (o) Carbon black plants (furnace process);
    (p) Primary lead smelters;
    (q) Fuel conversion plants;
    (r) Sintering plants;
    (s) Secondary metal production plants;
    (t) Chemical process plants--The term chemical processing plant 
shall not include ethanol production facilities that produce ethanol by 
natural fermentation included in NAICS codes 325193 or 312140;
    (u) Fossil-fuel boilers (or combination thereof) totaling more than 
250 million British thermal units per hour heat input;
    (v) Petroleum storage and transfer units with a total storage 
capacity exceeding 300,000 barrels;
    (w) Taconite ore processing plants;
    (x) Glass fiber processing plants;
    (y) Charcoal production plants;
    (z) Fossil fuel-fired steam electric plants of more than 250 million 
British thermal units per hour heat input;
    (aa) Any other stationary source category which, as of August 7, 
1980, is being regulated under section 111 or 112 of the Act.
    5. (i) Major modification means any physical change in or change in 
the method of operation of a major stationary source that would result 
in:
    (a) A significant emissions increase of a regulated NSR pollutant 
(as defined in paragraph II.A.31 of this Ruling); and
    (b) A significant net emissions increase of that pollutant from the 
major stationary source.
    (ii) Any significant emissions increase (as defined in paragraph 
II.A.23 of this Ruling) from any emissions units or net emissions 
increase (as defined in paragraph II.A.6 of this Ruling) at a major 
stationary source that is significant for volatile organic compounds 
shall be considered significant for ozone.
    (iii) A physical change or change in the method of operation shall 
not include:
    (a) Routine maintenance, repair, and replacement;
    (b) Use of an alternative fuel or raw material by reason of an order 
under section 2 (a) and (b) of the Energy Supply and Environmental 
Coordination Act of 1974 (or any superseding legislation) or by reason 
of a natural gas curtailment plan pursuant to the Federal Power Act;
    (c) Use of an alternative fuel by reason of an order or rule under 
section 125 of the Act;
    (d) Use of an alternative fuel at a steam generating unit to the 
extent that the fuel is generated from municipal solid waste;
    (e) Use of an alternative fuel or raw material by a stationary 
source which:
    (1) The source was capable of accommodating before December 21, 
1976, unless such change would be prohibited under any federally 
enforceable permit condition which was established after December 21, 
1976, pursuant to 40 CFR 52.21 or under regulations approved pursuant to 
40 CFR subpart I or Sec. 51.166; or
    (2) The source is approved to use under any permit issued under this 
ruling;
    (f) An increase in the hours of operation or in the production rate, 
unless such change is

[[Page 578]]

prohibited under any federally enforceable permit condition which was 
established after December 21, 1976 pursuant to 40 CFR 52.21 or under 
regulations approved pursuant to 40 CFR subpart I or Sec. 51.166;
    (g) Any change in ownership at a stationary source.
    (iv) For the purpose of applying the requirements of paragraph IV.H 
of this Ruling to modifications at major stationary sources of nitrogen 
oxides located in ozone nonattainment areas or in ozone transport 
regions, whether or not subject with respect to ozone to subpart 2, part 
D, title I of the Act, any significant net emissions increase of 
nitrogen oxides is considered significant for ozone.
    (v) Any physical change in, or change in the method of operation of, 
a major stationary source of volatile organic compounds that results in 
any increase in emissions of volatile organic compounds from any 
discrete operation, emissions unit, or other pollutant emitting activity 
at the source shall be considered a significant net emissions increase 
and a major modification for ozone, if the major stationary source is 
located in an extreme ozone nonattainment area that is subject to 
subpart 2, part D, title I of the Act.
    (vi) This definition shall not apply with respect to a particular 
regulated NSR pollutant when the major stationary source is complying 
with the requirements under paragraph IV.K of this ruling for a PAL for 
that pollutant. Instead, the definition at paragraph IV.K.2(viii) of 
this Ruling shall apply.
    (vii) Fugitive emissions shall not be included in determining for 
any of the purposes of this Ruling whether a physical change in or 
change in the method of operation of a major stationary source is a 
major modification, unless the source belongs to one of the source 
categories listed in paragraph II.A.4(iii) of this Ruling.
    6.(i) Net emissions increase means, with respect to any regulated 
NSR pollutant emitted by a major stationary source, the amount by which 
the sum of the following exceeds zero:
    (a) The increase in emissions from a particular physical change or 
change in the method of operation at a stationary source as calculated 
pursuant to paragraph IV.J of this Ruling; and
    (b) Any other increases and decreases in actual emissions at the 
major stationary source that are contemporaneous with the particular 
change and are otherwise creditable. Baseline actual emissions for 
calculating increases and decreases under this paragraph II.A.6(i)(b) 
shall be determined as provided in paragraph II.A.30 of this Ruling, 
except that paragraphs II.A.30(i)(c) and II.A.30(ii)(d) of this Ruling 
shall not apply.
    (ii) An increase or decrease in actual emissions is contemporaneous 
with the increase from the particular change only if it occurs between:
    (a) The date five years before construction on the particular change 
commences and
    (b) The date that the increase from the particular change occurs.
    (iii) An increase or decrease in actual emissions is creditable only 
if the reviewing authority has not relied on it in issuing a permit for 
the source under this Ruling, which permit is in effect when the 
increase in actual emissions from the particular change occurs.
    (iv) An increase in actual emissions is creditable only to the 
extent that the new level of actual emissions exceeds the old level.
    (v) A decrease in actual emissions is creditable only to the extent 
that:
    (a) The old level of actual emissions or the old level of allowable 
emissions, whichever is lower, exceeds the new level of actual 
emissions;
    (b) It is enforceable as a practical matter at and after the time 
that actual construction on the particular change begins;
    (c) The reviewing authority has not relied on it in issuing any 
permit under regulations approved pursuant to 40 CFR 51.165; and
    (d) It has approximately the same qualitative significance for 
public health and welfare as that attributed to the increase from the 
particular change.
    (vi) An increase that results from a physical change at a source 
occurs when the emissions unit on which construction occurred becomes 
operational and begins to emit a particular pollutant. Any replacement 
unit that requires shakedown becomes operational only after a reasonable 
shakedown period, not to exceed 180 days.
    (vii) Paragraph II.A.13(ii) of this Ruling shall not apply for 
determining creditable increases and decreases or after a change.
    7. Emissions unit means any part of a stationary source that emits 
or would have the potential to emit any regulated NSR pollutant and 
includes an electric utility steam generating unit as defined in 
paragraph II.A.21 of this Ruling. For purposes of this Ruling, there are 
two types of emissions units as described in paragraphs II.A.7(i) and 
(ii) of this Ruling.
    (i) A new emissions unit is any emissions unit which is (or will be) 
newly constructed and which has existed for less than 2 years from the 
date such emissions unit first operated.
    (ii) An existing emissions unit is any emissions unit that does not 
meet the requirements in paragraph II.A.7(i) of this Ruling.
    8. Secondary emissions means emissions which would occur as a result 
of the construction or operation of a major stationary source or major 
modification, but do not

[[Page 579]]

come from the major stationary source or major modification itself. For 
the purpose of this Ruling, secondary emissions must be specific, well 
defined, quantifiable, and impact the same general area as the 
stationary source or modification which causes the secondary emissions. 
Secondary emissions include emissions from any offsite support facility 
which would not be constructed or increase its emissions except as a 
result of the construction or operation of the major stationary source 
or major modification. Secondary emissions do not include any emissions 
which come directly from a mobile source, such as emissions from the 
tailpipe of a motor vehicle, from a train, or from a vessel.
    9. Fugitive emissions means those emissions which could not 
reasonably pass through a stack, chimney, vent, or other functionally 
equivalent opening.
    10.(i) Significant means, in reference to a net emissions increase 
or the potential of a source to emit any of the following pollutants, a 
rate of emissions that would equal or exceed any of the following rates:

                      Pollutant and Emissions Rate

Carbon monoxide: 100 tons per year (tpy)
Nitrogen oxides: 40 tpy
Sulfur dioxide: 40 tpy
Ozone: 40 tpy of Volatile organic compounds or Nitrogen oxides
Lead: 0.6 tpy
Particulate matter: 25 tpy of Particulate matter emissions
PM10: 15 tpy
PM2.5: 10 tpy of direct PM2.5 emissions; 40 tpy of 
Sulfur dioxide emissions, 40 tpy of Nitrogen oxides emissions, or 40 tpy 
of Volatile organic compound emissions, to the extent that any such 
pollutant is defined as a precursor for PM2.5 in paragraph 
II.A.31 of this Ruling.

    (ii) Notwithstanding the significant emissions rate for ozone in 
paragraph II.A.10(i) of this Ruling, significant means, in reference to 
an emissions increase or a net emissions increase, any increase in 
actual emissions of volatile organic compounds that would result from 
any physical change in, or change in the method of operation of, a major 
stationary source locating in a serious or severe ozone nonattainment 
area that is subject to subpart 2, part D, title I of the Act, if such 
emissions increase of volatile organic compounds exceeds 25 tons per 
year.
    (iii) For the purposes of applying the requirements of paragraph 
IV.H of this Ruling to modifications at major stationary sources of 
nitrogen oxides located in an ozone nonattainment area or in an ozone 
transport region, the significant emission rates and other requirements 
for volatile organic compounds in paragraphs II.A.10(i), (ii), and (v) 
of this Ruling shall apply to nitrogen oxides emissions.
    (iv) Notwithstanding the significant emissions rate for carbon 
monoxide under paragraph II.A.10(i) of this Ruling, significant means, 
in reference to an emissions increase or a net emissions increase, any 
increase in actual emissions of carbon monoxide that would result from 
any physical change in, or change in the method of operation of, a major 
stationary source in a serious nonattainment area for carbon monoxide if 
such increase equals or exceeds 50 tons per year, provided the 
Administrator has determined that stationary sources contribute 
significantly to carbon monoxide levels in that area.
    (v) Notwithstanding the significant emissions rates for ozone under 
paragraphs II.A.10(i) and (ii) of this Ruling, any increase in actual 
emissions of volatile organic compounds from any emissions unit at a 
major stationary source of volatile organic compounds located in an 
extreme ozone nonattainment area that is subject to subpart 2, part D, 
title I of the Act shall be considered a significant net emissions 
increase.
    (vi) In any nonattainment area for PM2.5 in which a state 
must regulate Ammonia as a regulated NSR pollutant (as a 
PM2.5 precursor) as defined in paragraph II.A.31 of this 
Ruling, the reviewing authority shall define ``significant'' for Ammonia 
for that area and establish a record to document its supporting basis. 
All sources with modification projects with increases in Ammonia 
emissions that are not subject to Section IV of this Ruling must 
maintain records of the non-applicability of Section IV that reference 
the definition of ``significant'' for Ammonia that is established by the 
reviewing authority in the nonattainment area where the source is 
located.
    11. Allowable emissions means the emissions rate calculated using 
the maximum rated capacity of the source (unless the source is subject 
to federally enforceable limits which restrict the operating rate, or 
hours of operation, or both) and the most stringent of the following:
    (i) Applicable standards as set forth in 40 CFR parts 60 and 61;
    (ii) Any applicable State Implementation Plan emissions limitation, 
including those with a future compliance date; or
    (iii) The emissions rate specified as a federally enforceable permit 
condition, including those with a future compliance date.
    12. Federally enforceable means all limitations and conditions which 
are enforceable by the Administrator, including those requirements 
developed pursuant to 40 CFR parts 60 and 61, requirements within any 
applicable State implementation plan, any permit requirements 
established pursuant to 40 CFR 52.21 or under regulations approved 
pursuant to 40 CFR part 51, subpart I, including

[[Page 580]]

operating permits issued under an EPA-approved program that is 
incorporated into the State implementation plan and expressly requires 
adherence to any permit issued under such program.
    13. (i) Actual emissions means the actual rate of emissions of a 
regulated NSR pollutant from an emissions unit, as determined in 
accordance with paragraphs II.A.13(ii) through (iv) of this Ruling, 
except that this definition shall not apply for calculating whether a 
significant emissions increase has occurred, or for establishing a PAL 
under paragraph IV.K of this Ruling. Instead, paragraphs II.A.24 and 30 
of this Ruling shall apply for those purposes.
    (ii) In general, actual emissions as of a particular date shall 
equal the average rate, in tons per year, at which the unit actually 
emitted the pollutant during a consecutive 24-month period which 
precedes the particular date and which is representative of normal 
source operation. The reviewing authority shall allow the use of a 
different time period upon a determination that it is more 
representative of normal source operation. Actual emissions shall be 
calculated using the unit's actual operating hours, production rates, 
and types of materials processed, stored, or combusted during the 
selected time period.
    (iii) The reviewing authority may presume that source-specific 
allowable emissions for the unit are equivalent to the actual emissions 
of the unit.
    (iv) For any emissions unit that has not begun normal operations on 
the particular date, actual emissions shall equal the potential to emit 
of the unit on that date.
    14. Construction means any physical change or change in the method 
of operation (including fabrication, erection, installation, demolition, 
or modification of an emissions unit) that would result in a change in 
emissions.
    15. Commence as applied to construction of a major stationary source 
or major modification means that the owner or operator has all necessary 
preconstruction approvals or permits and either has:
    (i) Begun, or caused to begin, a continuous program of actual on-
site construction of the source, to be completed within a reasonable 
time; or
    (ii) Entered into binding agreements or contractual obligations, 
which cannot be cancelled or modified without substantial loss to the 
owner or operator, to undertake a program of actual construction of the 
source to be completed within a reasonable time.
    16. Necessary preconstruction approvals or permits means those 
permits or approvals required under Federal air quality control laws and 
regulations and those air quality control laws and regulations which are 
part of the applicable State Implementation Plan.
    17. Begin actual construction means, in general, initiation of 
physical on-site construction activities on an emissions unit which are 
of a permanent nature. Such activities include, but are not limited to, 
installation of building supports and foundations, laying of underground 
pipework, and construction of permanent storage structures. With respect 
to a change in method of operating this term refers to those on-site 
activities other than preparatory activities which mark the initiation 
of the change.
    18. Lowest achievable emission rate (LAER) means, for any source, 
the more stringent rate of emissions based on the following:
    (i) The most stringent emissions limitation which is contained in 
the implementation plan of any State for such class or category of 
stationary source, unless the owner or operator of the proposed 
stationary source demonstrates that such limitations are not achievable; 
or
    (ii) The most stringent emissions limitation which is achieved in 
practice by such class or category of stationary source. This 
limitation, when applied to a modification, means the lowest achievable 
emissions rate for the new or modified emissions units within the 
stationary source. In no event shall the application of this term permit 
a proposed new or modified stationary source to emit any pollutant in 
excess of the amount allowable under applicable new source standards of 
performance.
    19. Resource recovery facility means any facility at which solid 
waste is processed for the purpose of extracting, converting to energy, 
or otherwise separating and preparing solid waste for reuse. Energy 
conversion facilities must utilize solid waste to provide more than 50 
percent of the heat input to be considered a resource recovery facility 
under this Ruling.
    20. Volatile organic compounds (VOC) is as defined in Sec. 
51.100(s) of this part.
    21. Electric utility steam generating unit means any steam electric 
generating unit that is constructed for the purpose of supplying more 
than one-third of its potential electric output capacity and more than 
25 MW electrical output to any utility power distribution system for 
sale. Any steam supplied to a steam distribution system for the purpose 
of providing steam to a steam-electric generator that would produce 
electrical energy for sale is also considered in determining the 
electrical energy output capacity of the affected facility.
    22. Pollution prevention means any activity that through process 
changes, product reformulation or redesign, or substitution of less 
polluting raw materials, eliminates or reduces the release of air 
pollutants (including fugitive emissions) and other pollutants to the 
environment prior to recycling, treatment, or disposal; it does not mean 
recycling (other than certain ``in-process recycling''

[[Page 581]]

practices), energy recovery, treatment, or disposal.
    23. Significant emissions increase means, for a regulated NSR 
pollutant, an increase in emissions that is significant (as defined in 
paragraph II.A.10 of this Ruling) for that pollutant.
    24. (i) Projected actual emissions means, the maximum annual rate, 
in tons per year, at which an existing emissions unit is projected to 
emit a regulated NSR pollutant in any one of the 5 years (12-month 
period) following the date the unit resumes regular operation after the 
project, or in any one of the 10 years following that date, if the 
project involves increasing the emissions unit's design capacity or its 
potential to emit of that regulated NSR pollutant and full utilization 
of the unit would result in a significant emissions increase or a 
significant net emissions increase at the major stationary source.
    (ii) In determining the projected actual emissions under paragraph 
II.A.24(i) of this Ruling before beginning actual construction, the 
owner or operator of the major stationary source:
    (a) Shall consider all relevant information, including but not 
limited to, historical operational data, the company's own 
representations, the company's expected business activity and the 
company's highest projections of business activity, the company's 
filings with the State or Federal regulatory authorities, and compliance 
plans under the approved plan; and
    (b) Shall include fugitive emissions to the extent quantifiable, and 
emissions associated with startups, shutdowns, and malfunctions; and
    (c) Shall exclude, in calculating any increase in emissions that 
results from the particular project, that portion of the unit's 
emissions following the project that an existing unit could have 
accommodated during the consecutive 24-month period used to establish 
the baseline actual emissions under paragraph II.A.30 of this Ruling and 
that are also unrelated to the particular project, including any 
increased utilization due to product demand growth; or,
    (d) In lieu of using the method set out in paragraphs II.A.24(ii)(a) 
through (c) of this Ruling, may elect to use the emissions unit's 
potential to emit, in tons per year, as defined under paragraph II.A.3 
of this Ruling.
    25. Nonattainment major new source review (NSR) program means a 
major source preconstruction permit program that implements Sections I 
through VI of this Ruling, or a program that has been approved by the 
Administrator and incorporated into the plan to implement the 
requirements of Sec. 51.165 of this part. Any permit issued under such 
a program is a major NSR permit.
    26. Continuous emissions monitoring system (CEMS) means all of the 
equipment that may be required to meet the data acquisition and 
availability requirements of this Ruling, to sample, condition (if 
applicable), analyze, and provide a record of emissions on a continuous 
basis.
    27. Predictive emissions monitoring system (PEMS) means all of the 
equipment necessary to monitor process and control device operational 
parameters (for example, control device secondary voltages and electric 
currents) and other information (for example, gas flow rate, 
O2 or CO2 concentrations), and calculate and 
record the mass emissions rate (for example, lb/hr) on a continuous 
basis.
    28. Continuous parameter monitoring system (CPMS) means all of the 
equipment necessary to meet the data acquisition and availability 
requirements of this Ruling, to monitor process and control device 
operational parameters (for example, control device secondary voltages 
and electric currents) and other information (for example, gas flow 
rate, O2 or CO2 concentrations), and to record 
average operational parameter value(s) on a continuous basis.
    29. Continuous emissions rate monitoring system (CERMS) means the 
total equipment required for the determination and recording of the 
pollutant mass emissions rate (in terms of mass per unit of time).
    30. Baseline actual emissions means the rate of emissions, in tons 
per year, of a regulated NSR pollutant, as determined in accordance with 
paragraphs II.A.30(i) through (iv) of this Ruling.
    (i) For any existing electric utility steam generating unit, 
baseline actual emissions means the average rate, in tons per year, at 
which the unit actually emitted the pollutant during any consecutive 24-
month period selected by the owner or operator within the 5-year period 
immediately preceding when the owner or operator begins actual 
construction of the project. The reviewing authority shall allow the use 
of a different time period upon a determination that it is more 
representative of normal source operation.
    (a) The average rate shall include fugitive emissions to the extent 
quantifiable, and emissions associated with startups, shutdowns, and 
malfunctions.
    (b) The average rate shall be adjusted downward to exclude any non-
compliant emissions that occurred while the source was operating above 
any emission limitation that was legally enforceable during the 
consecutive 24-month period.
    (c) For a regulated NSR pollutant, when a project involves multiple 
emissions units, only one consecutive 24-month period must be used to 
determine the baseline actual emissions for the emissions units being 
changed. A different consecutive 24-month period can be used for each 
regulated NSR pollutant.

[[Page 582]]

    (d) The average rate shall not be based on any consecutive 24-month 
period for which there is inadequate information for determining annual 
emissions, in tons per year, and for adjusting this amount if required 
by paragraph II.A.30(i)(b) of this Ruling.
    (ii) For an existing emissions unit (other than an electric utility 
steam generating unit), baseline actual emissions means the average 
rate, in tons per year, at which the emissions unit actually emitted the 
pollutant during any consecutive 24-month period selected by the owner 
or operator within the 10-year period immediately preceding either the 
date the owner or operator begins actual construction of the project, or 
the date a complete permit application is received by the reviewing 
authority for a permit required either under this Ruling or under a plan 
approved by the Administrator, whichever is earlier, except that the 10-
year period shall not include any period earlier than November 15, 1990.
    (a) The average rate shall include fugitive emissions to the extent 
quantifiable, and emissions associated with startups, shutdowns, and 
malfunctions.
    (b) The average rate shall be adjusted downward to exclude any non-
compliant emissions that occurred while the source was operating above 
an emission limitation that was legally enforceable during the 
consecutive 24-month period.
    (c) The average rate shall be adjusted downward to exclude any 
emissions that would have exceeded an emission limitation with which the 
major stationary source must currently comply, had such major stationary 
source been required to comply with such limitations during the 
consecutive 24-month period. However, if an emission limitation is part 
of a maximum achievable control technology standard that the 
Administrator proposed or promulgated under part 63 of this chapter, the 
baseline actual emissions need only be adjusted if the State has taken 
credit for such emissions reductions in an attainment demonstration or 
maintenance plan.
    (d) For a regulated NSR pollutant, when a project involves multiple 
emissions units, only one consecutive 24-month period must be used to 
determine the baseline actual emissions for the emissions units being 
changed. A different consecutive 24-month period can be used for each 
regulated NSR pollutant.
    (e) The average rate shall not be based on any consecutive 24-month 
period for which there is inadequate information for determining annual 
emissions, in tons per year, and for adjusting this amount if required 
by paragraphs II.A.30(ii)(b) and (c) of this Ruling.
    (iii) For a new emissions unit, the baseline actual emissions for 
purposes of determining the emissions increase that will result from the 
initial construction and operation of such unit shall equal zero; and 
thereafter, for all other purposes, shall equal the unit's potential to 
emit.
    (iv) For a PAL for a major stationary source, the baseline actual 
emissions shall be calculated for existing electric utility steam 
generating units in accordance with the procedures contained in 
paragraph II.A.30(i) of this Ruling, for other existing emissions units 
in accordance with the procedures contained in paragraph II.A.30(ii) of 
this Ruling, and for a new emissions unit in accordance with the 
procedures contained in paragraph II.A.30(iii) of this Ruling.
    31. Regulated NSR pollutant, for purposes of this Ruling, means the 
following:
    (i) Nitrogen oxides or any volatile organic compounds;
    (ii) Any pollutant for which a national ambient air quality standard 
has been promulgated. This includes, but is not limited to, the 
following:
    (a) PM2.5 emissions and PM10 emissions shall 
include gaseous emissions from a source or activity, which condense to 
form particulate matter at ambient temperatures. On or after January 1, 
2011, such condensable particulate matter shall be accounted for in 
applicability determinations and in establishing emissions limitations 
for PM2.5 and PM10 in permits issued under this 
ruling. Compliance with emissions limitations for PM2.5 and 
PM10 issued prior to this date shall not be based on 
condensable particulate matter unless required by the terms and 
conditions of the permit or the applicable implementation plan. 
Applicability determinations made prior to this date without accounting 
for condensable particulate matter shall not be considered in violation 
of this section unless the applicable implementation plan required 
condensable particulate matter to be included.
    (b) Any pollutant that is identified under this paragraph 
II.A.31(ii)(2) as a constituent or precursor of a general pollutant 
listed under paragraph II.A.31(i) or (ii) of this Ruling, provided that 
such constituent or precursor pollutant may only be regulated under NSR 
as part of regulation of the general pollutant. Precursors identified by 
the Administrator for purposes of NSR are the following:
    (1) Volatile organic compounds and nitrogen oxides are precursors to 
ozone in all ozone nonattainment areas.
    (2) Sulfur dioxide and Nitrogen oxides are regulated as precursors 
to PM2.5 in all PM2.5 nonattainment areas.
    (3) For any area that was designated nonattainment for 
PM2.5 on or before April 15, 2015, Volatile organic compounds 
and Ammonia shall be regulated as precursors to PM2.5 
beginning on April 15, 2017, with respect to any permit issued for 
PM2.5, unless the following conditions are met: The state 
submits

[[Page 583]]

a SIP for the Administrator's review containing the state's 
preconstruction review provisions for PM2.5 consistent with 
Sec. 51.165 and a complete NNSR precursor demonstration consistent with 
Sec. 51.1006(a)(3); and such SIP is determined to be complete by the 
Administrator or deemed to be complete by operation of law in accordance 
with section 110(k)(1)(B) of the Act by April 15, 2017. If these 
conditions are met, the precursor(s) addressed by the NNSR precursor 
demonstration (Volatile organic compounds, Ammonia, or both) shall not 
be regulated as a precursor to PM2.5 in such area. If the 
Administrator subsequently disapproves the state's preconstruction 
review provisions for PM2.5 and the NNSR precursor 
demonstration, the precursor(s) addressed by the NNSR precursor 
demonstration shall be regulated as a precursor to PM2.5 
under this Ruling in such area as of April 15, 2017, or the effective 
date of the disapproval, whichever date is later.
    (4) For any area that is designated nonattainment for 
PM2.5 after April 15, 2015, and was not already designated 
nonattainment for PM2.5 on or immediately prior to such date, 
Volatile organic compounds and Ammonia shall be regulated as precursors 
to PM2.5 under this Ruling beginning 24 months from the date 
of designation as nonattainment for PM2.5 with respect to any 
permit issued for PM2.5, unless the following conditions are 
met: the state submits a SIP for the Administrator's review which 
contains the state's preconstruction review provisions for 
PM2.5 consistent with Sec. 51.165 and a complete NNSR 
precursor demonstration consistent with Sec. 51.1006(a)(3); and such 
SIP is determined to be complete by the Administrator or deemed to be 
complete by operation of law in accordance with section 110(k)(1)(B) of 
the Act by the date 24 months from the date of designation. If these 
conditions are met, the precursor(s) addressed by the NNSR precursor 
demonstration (Volatile organic compounds, Ammonia, or both) shall not 
be regulated as a precursor to PM2.5 in such area. If the 
Administrator subsequently disapproves the state's preconstruction 
review provisions for PM2.5 and the NNSR precursor 
demonstration, the precursor(s) addressed by the NNSR precursor 
demonstration shall be regulated as a precursor to PM2.5 
under this Ruling in such area as of the date 24 months from the date of 
designation, or the effective date of the disapproval, whichever date is 
later.
    32. Reviewing authority means the State air pollution control 
agency, local agency, other State agency, Indian tribe, or other agency 
issuing permits under this Ruling or authorized by the Administrator to 
carry out a permit program under Sec. Sec. 51.165 and 51.166 of this 
part, or the Administrator in the case of EPA-implemented permit 
programs under this Ruling or under Sec. 52.21 of this chapter.
    33. Project means a physical change in, or change in the method of 
operation of, an existing major stationary source.
    34. Best available control technology (BACT) means an emissions 
limitation (including a visible emissions standard) based on the maximum 
degree of reduction for each regulated NSR pollutant which would be 
emitted from any proposed major stationary source or major modification 
which the reviewing authority, on a case-by-case basis, taking into 
account energy, environmental, and economic impacts and other costs, 
determines is achievable for such source or modification through 
application of production processes or available methods, systems, and 
techniques, including fuel cleaning or treatment or innovative fuel 
combustion techniques for control of such pollutant. In no event shall 
application of best available control technology result in emissions of 
any pollutant which would exceed the emissions allowed by any applicable 
standard under 40 CFR part 60 or 61. If the reviewing authority 
determines that technological or economic limitations on the application 
of measurement methodology to a particular emissions unit would make the 
imposition of an emissions standard infeasible, a design, equipment, 
work practice, operational standard, or combination thereof, may be 
prescribed instead to satisfy the requirement for the application of 
BACT. Such standard shall, to the degree possible, set forth the 
emissions reduction achievable by implementation of such design, 
equipment, work practice or operation, and shall provide for compliance 
by means which achieve equivalent results.
    35. Prevention of Significant Deterioration (PSD) permit means any 
permit that is issued under a major source preconstruction permit 
program that has been approved by the Administrator and incorporated 
into the plan to implement the requirements of Sec. 51.166 of this 
chapter, or under the program in Sec. 52.21 of this chapter.
    36. Federal Land Manager means, with respect to any lands in the 
United States, the Secretary of the department with authority over such 
lands.
    B. Review of all sources for emission limitation compliance. The 
reviewing authority must examine each proposed major new source and 
proposed major modification \1\ to determine if such a source will meet 
all applicable emission requirements in the SIP, any applicable new 
source performance standard in part 60 or any national emission standard 
for hazardous air pollutants in part 61 or part 63 of this chapter. If 
the reviewing authority determines that the proposed major new source 
cannot meet the applicable

[[Page 584]]

emission requirements, the permit to construct must be denied.
---------------------------------------------------------------------------

    \1\ Hereafter the term source will be used to denote both any source 
and any modification.
---------------------------------------------------------------------------

    C. Review of specified sources for air quality impact. In addition, 
the reviewing authority must determine whether the major stationary 
source or major modification would be constructed in an area designated 
in 40 CFR 81.300 et seq. as nonattainment for a pollutant for which the 
stationary source or modification is major.
    D.-E. [Reserved]
    F. Fugitive emission sources. Section IV.A. of this Ruling shall not 
apply to a source or modification that would be a major stationary 
source or major modification only if fugitive emissions, to the extent 
quantifiable, are considered in calculating the potential to emit of the 
stationary source or modification and such source does not belong to any 
of the following categories:
    (1) Coal cleaning plants (with thermal dryers);
    (2) Kraft pulp mills;
    (3) Portland cement plants;
    (4) Primary zinc smelters;
    (5) Iron and steel mills;
    (6) Primary aluminum ore reduction plants;
    (7) Primary copper smelters;
    (8) Municipal incinerators capable of charging more than 250 tons of 
refuse per day;
    (9) Hydrofluoric, sulfuric, or nitric acid plants;
    (10) Petroleum refineries;
    (11) Lime plants;
    (12) Phosphate rock processing plants;
    (13) Coke oven batteries;
    (14) Sulfur recovery plants;
    (15) Carbon black plants (furnace process);
    (16) Primary lead smelters;
    (17) Fuel conversion plants;
    (18) Sintering plants;
    (19) Secondary metal production plants;
    (20) Chemical process plants--The term chemical processing plant 
shall not include ethanol production facilities that produce ethanol by 
natural fermentation included in NAICS codes 325193 or 312140;
    (21) Fossil-fuel boilers (or combination thereof) totaling more than 
250 million British thermal units per hour heat input;
    (22) Petroleum storage and transfer units with a total storage 
capacity exceeding 300,000 barrels;
    (23) Taconite ore processing plants;
    (24) Glass fiber processing plants;
    (25) Charcoal production plants;
    (26) Fossil fuel-fired steam electric plants of more than 250 
million British thermal units per hour heat input;
    (27) Any other stationary source category which, as of August 7, 
1980, is being regulated under section 111 or 112 of the Act.
    G. Secondary emissions. Secondary emissions need not be considered 
in determining whether the emission rates in Section II.C. above would 
be exceeded. However, if a source is subject to this Ruling on the basis 
of the direct emissions from the source, the applicable conditions of 
this Ruling must also be met for secondary emissions. However, secondary 
emissions may be exempt from Conditions 1 and 2 of Section IV. Also, 
since EPA's authority to perform or require indirect source review 
relating to mobile sources regulated under Title II of the Act (motor 
vehicles and aircraft) has been restricted by statute, consideration of 
the indirect impacts of motor vehicles and aircraft traffic is not 
required under this Ruling.

III. Sources Locating in Designated Clean or Unclassifiable Areas Which 
   Would Cause or Contribute to a Violation of a National Ambient Air 
                            Quality Standard

    A. This section applies only to major sources or major modifications 
which would locate in an area designated in 40 CFR 81.300 et seq. as 
attainment or unclassifiable in a State where EPA has not yet approved 
the State preconstruction review program required by 40 CFR 51.165(b), 
if the source or modification would exceed the following significance 
levels at any locality that does not meet the NAAQS:

----------------------------------------------------------------------------------------------------------------
                                                                     Averaging time (hours)
          Pollutant                 Annual     -----------------------------------------------------------------
                                                       24               8               3               1
----------------------------------------------------------------------------------------------------------------
SO2..........................  1.0 [micro]g/    5 [micro]g/m\3\  ...............  25 [micro]g/
                                m\3\                                               m\3\
PM10.........................  1.0 [micro]g/    5 [micro]g/m\3\  ...............
                                m\3\
PM2.5........................  0.3 [micro]g/    1.2 [micro]g/    ...............
                                m\3\             m\3\
NO2..........................  1.0 [micro]g/    ...............  ...............
                                m\3\
CO...........................  ...............  ...............  0.5 mg/m\3\      .............  2 mg/m\3\
----------------------------------------------------------------------------------------------------------------

    B. Sources to which this section applies must meet Conditions 1, 2, 
and 4 of Section IV.A. of this ruling. \2\ However, such sources

[[Page 585]]

may be exempt from Condition 3 of Section IV.A. of this ruling.
---------------------------------------------------------------------------

    \2\ The discussion in this paragraph is a proposal, but represents 
EPA's interim policy until final rulemaking is completed.
---------------------------------------------------------------------------

    C. Review of specified sources for air quality impact. For stable 
air pollutants (i.e., SO2, particulate matter and CO), the 
determination of whether a source will cause or contribute to a 
violation of an NAAQS generally should be made on a case-by-case basis 
as of the proposed new source's start-up date using the source's 
allowable emissions in an atmospheric simulation model (unless a source 
will clearly impact on a receptor which exceeds an NAAQS).
    For sources of nitrogen oxides, the initial determination of whether 
a source would cause or contribute to a violation of the NAAQS for 
NO2 should be made using an atmospheric simulation model 
assuming all the nitric oxide emitted is oxidized to NO2 by 
the time the plume reaches ground level. The initial concentration 
estimates may be adjusted if adequate data are available to account for 
the expected oxidation rate.
    For ozone, sources of volatile organic compounds, locating outside a 
designated ozone nonattainment area, will be presumed to have no 
significant impact on the designated nonattainment area. If ambient 
monitoring indicates that the area of source location is in fact 
nonattainment, then the source may be permitted under the provisions of 
any State plan adopted pursuant to section 110(a)(2)(D) of the Act until 
the area is designated nonattainment and a State Implementation Plan 
revision is approved. If no State plan pursuant to section 110(a)(2)(D) 
has been adopted and approved, then this Ruling shall apply.
    As noted above, the determination as to whether a source would cause 
or contribute to a violation of an NAAQS should be made as of the new 
source's start-up date. Therefore, if a designated nonattainment area is 
projected to be an attainment area as part of an approved SIP control 
strategy by the new source start-up date, offsets would not be required 
if the new source would not cause a new violation.
    D. Sources locating in clean areas, but would cause a new violating 
of an NAAQS. If the reviewing authority finds that the emissions from a 
proposed source would cause a new violation of an NAAQS, but would not 
contribute to an existing violation, approval may be granted only if 
both of the following conditions are met:
    Condition 1. The new source is required to meet a more stringent 
emission limitation \3\ and/or the control of existing sources below 
allowable levels is required so that the source will not cause a 
violation of any NAAQS.
---------------------------------------------------------------------------

    \3\ If the reviewing authority determines that technological or 
economic limitations on the application of measurement methodology to a 
particular class of sources would make the imposition of an enforceable 
numerical emission standard infeasible, the authority may instead 
prescribe a design, operational or equipment standard. In such cases, 
the reviewing authority shall make its best estimate as to the emission 
rate that will be achieved and must specify that rate in the required 
submission to EPA (see Part V). Any permits issued without an 
enforceable numerical emission standard must contain enforceable 
conditions which assure that the design characteristics or equipment 
will be properly maintained (or that the operational conditions will be 
properly performed) so as to continuously achieve the assumed degree of 
control. Such conditions shall be enforceable as emission limitations by 
private parties under section 304. Hereafter, the term emission 
limitation shall also include such design, operational, or equipment 
standards.
---------------------------------------------------------------------------

    Condition 2. The new emission limitations for the new source as well 
as any existing sources affected must be enforceable in accordance with 
the mechanisms set forth in Section V of this appendix.

    IV. Sources That Would Locate in a Designated Nonattainment Area

    A. Conditions for approval. If the reviewing authority finds that 
the major stationary source or major modification would be constructed 
in an area designated in 40 CFR 81.300 et seq as nonattainment for a 
pollutant for which the stationary source or modification is major, 
approval may be granted only if the following conditions are met:
    Condition 1. The new source is required to meet an emission 
Limitation \4\ which specifies the lowest achievable emission rate for 
such source.
---------------------------------------------------------------------------

    \4\ If the reviewing authority determines that technological or 
economic limitations on the application of measurement methodology to a 
particular class of sources would make the imposition of an enforceable 
numerical emission standard infeasible, the authority may instead 
prescribe a design, operational or equipment standard. In such cases, 
the reviewing authority shall make its best estimate as to the emission 
rate that will be achieved and must specify that rate in the required 
submission to EPA (see Part V). Any permits issued without an 
enforceable numerical emission standard must contain enforceable 
conditions which assure that the design characteristics or equipment 
will be properly maintained (or that the operational conditions will be 
properly performed) so as to continuously achieve the assumed degree of 
control. Such conditions shall be enforceable as emission limitations by 
private parties under section 304. Hereafter, the term emission 
limitation shall also include such design, operational, or equipment 
standards.

---------------------------------------------------------------------------

[[Page 586]]

    Condition 2. The applicant must certify that all existing major 
sources owned or operated by the applicant (or any entity controlling, 
controlled by, or under common control with the applicant) in the same 
State as the proposed source are in compliance with all applicable 
emission limitations and standards under the Act (or are in compliance 
with an expeditious schedule which is Federally enforceable or contained 
in a court decree).
    Condition 3. Emission reductions (offsets) from existing sources \5\ 
in the area of the proposed source (whether or not under the same 
ownership) are required such that there will be reasonable progress 
toward attainment of the applicable NAAQS. \6\ Except as provided in 
paragraph IV.G.5 of this Ruling (addressing PM2.5 and its 
precursors), only intrapollutant emission offsets will be acceptable 
(e.g., hydrocarbon increases may not be offset against SO2 
reductions).
    \5\ Subject to the provisions of paragraph IV.C of this Ruling.
    \6\ The discussion in this paragraph is a proposal, but represents 
EPA's interim policy until final rulemaking is completed.
    Condition 4. The emission offsets will provide a positive net air 
quality benefit in the affected area (see Section IV.D. below). 
Atmospheric simulation modeling is not necessary for volatile organic 
compounds and NOX. Fulfillment of Condition 3 and Section 
IV.D. will be considered adequate to meet this condition.
    Condition 5. The permit applicant shall conduct an analysis of 
alternative sites, sizes, production processes and environmental control 
techniques for such proposed source that demonstrates that the benefits 
of the proposed source significantly outweigh the environmental and 
social costs imposed as a result of its location, construction or 
modification.
    B. Exemptions from certain conditions. The reviewing authority may 
exempt the following sources from Condition 1 under Section III or 
Conditions 3 and 4. Section IV.A.:
    (i) Resource recovery facilities burning municipal solid waste, and 
(ii) sources which must switch fuels due to lack of adequate fuel 
supplies or where a source is required to be modified as a result of EPA 
regulations (e.g., lead-in-fuel requirements) and no exemption from such 
regulation is available to the source. Such an exemption may be granted 
only if:
    1. The applicant demonstrates that it made its best efforts to 
obtain sufficient emission offsets to comply with Condition 1 under 
Section III or Conditions 3 and 4 under Section IV.A. and that such 
efforts were unsuccessful;
    2. The applicant has secured all available emission offsets; and
    3. The applicant will continue to seek the necessary emission 
offsets and apply them when they become available.
    Such an exemption may result in the need to revise the SIP to 
provide additional control of existing sources.
    Temporary emission sources, such as pilot plants, portable 
facilities which will be relocated outside of the nonattainment area 
after a short period of time, and emissions resulting from the 
construction phase of a new source, are exempt from Conditions 3 and 4 
of this section.
    C. Baseline for determining credit for emission and air quality 
offsets. The baseline for determining credit for emission and air 
quality offsets will be the SIP emission limitations in effect at the 
time the application to construct or modify a source is filed. Thus, 
credit for emission offset purposes may be allowable for existing 
control that goes beyond that required by the SIP. Emission offsets 
generally should be made on a pounds per hour basis when all facilities 
involved in the emission offset calculations are operating at their 
maximum expected or allowed production rate. The reviewing agency should 
specify other averaging periods (e.g., tons per year) in addition to the 
pounds per hour basis if necessary to carry out the intent of this 
Ruling. When offsets are calculated on a tons per year basis, the 
baseline emissions for existing sources providing the offsets should be 
calculated using the actual annual operating hours for the previous one 
or two year period (or other appropriate period if warranted by cyclical 
business conditions). Where the SIP requires certain hardware controls 
in lieu of an emission limitation (e.g., floating roof tanks for 
petroleum storage), baseline allowable emissions should be based on 
actual operating conditions for the previous one or two year period 
(i.e., actual throughput and vapor pressures) in conjunction with the 
required hardware controls.
    1. No meaningful or applicable SIP requirement. Where the applicable 
SIP does not contain an emission limitation for a source or source 
category, the emission offset baseline involving such sources shall be 
the actual emissions determined in accordance with the discussion above 
regarding operating conditions.
    Where the SIP emission limit allows greater emissions than the 
uncontrolled emission rate of the source (as when a State has a single 
particulate emission limit for all fuels), emission offset credit will 
be allowed only for control below the uncontrolled emission rate.
    2. Combustion of fuels. Generally, the emissions for determining 
emission offset credit involving an existing fuel combustion source

[[Page 587]]

will be the allowable emissions under the SIP for the type of fuel being 
burned at the time the new source application is filed (i.e., if the 
existing source has switched to a different type of fuel at some earlier 
date, any resulting emission reduction [either actual or allowable] 
shall not be used for emission offset credit). If the existing source 
commits to switch to a cleaner fuel at some future date, emission offset 
credit based on the allowable emissions for the fuels involved is not 
acceptable unless the permit is conditioned to require the use of a 
specified alternative control measure which would achieve the same 
degree of emission reduction should the source switch back to a dirtier 
fuel at some later date. The reviewing authority should ensure that 
adequate long-term supplies of the new fuel are available before 
granting emission offset credit for fuel switches.
    3. Emission Reduction Credits from Shutdowns and Curtailments.
    (i) Emissions reductions achieved by shutting down an existing 
source or curtailing production or operating hours may be generally 
credited for offsets if they meet the requirements in paragraphs 
IV.C.3.i.1. through 2 of this section.
    (1) Such reductions are surplus, permanent, quantifiable, and 
federally enforceable.
    (2) The shutdown or curtailment occurred after the last day of the 
base year for the SIP planning process. For purposes of this paragraph, 
a reviewing authority may choose to consider a prior shutdown or 
curtailment to have occurred after the last day of the base year if the 
projected emissions inventory used to develop the attainment 
demonstration explicitly includes the emissions from such previously 
shutdown or curtailed emission units. However, in no event may credit be 
given for shutdowns that occurred before August 7, 1977.
    (ii) Emissions reductions achieved by shutting down an existing 
source or curtailing production or operating hours and that do not meet 
the requirements in paragraphs IV.C.3.i.1. through 2 of this section may 
be generally credited only if:
    (1) The shutdown or curtailment occurred on or after the date the 
new source permit application is filed; or
    (2) The applicant can establish that the proposed new source is a 
replacement for the shutdown or curtailed source, and the emissions 
reductions achieved by the shutdown or curtailment met the requirements 
of paragraphs IV.C.3.i.1. through 2 of this section.
    4. Credit for VOC substitution. As set forth in the Agency's 
``Recommended Policy on Control of Volatile Organic Compounds'' (42 FR 
35314, July 8, 1977), EPA has found that almost all non-methane VOCs are 
photochemically reactive and that low reactivity VOCs eventually form as 
much ozone as the highly reactive VOCs. Therefore, no emission offset 
credit may be allowed for replacing one VOC compound with another of 
lesser reactivity, except for those compounds listed in Table 1 of the 
above policy statement.
    5. ``Banking'' of emission offset credit. For new sources obtaining 
permits by applying offsets after January 16, 1979, the reviewing 
authority may allow offsets that exceed the requirements of reasonable 
progress toward attainment (Condition 3) to be ``banked'' (i.e., saved 
to provide offsets for a source seeking a permit in the future) for use 
under this Ruling. Likewise, the reviewing authority may allow the owner 
of an existing source that reduces its own emissions to bank any 
resulting reductions beyond those required by the SIP for use under this 
Ruling, even if none of the offsets are applied immediately to a new 
source permit. A reviewing authority may allow these banked offsets to 
be used under the preconstruction review program required by Part D, as 
long as these banked emissions are identified and accounted for in the 
SIP control strategy. A reviewing authority may not approve the 
construction of a source using banked offsets if the new source would 
interfere with the SIP control strategy or if such use would violate any 
other condition set forth for use of offsets. To preserve banked 
offsets, the reviewing authority should identify them in either a SIP 
revision or a permit, and establish rules as to how and when they may be 
used.
    6. Offset credit for meeting NSPS or NESHAPS. Where a source is 
subject to an emission limitation established in a New Source 
Performance Standard (NSPS) or a National Emission Standard for 
Hazardous Air Pollutants (NESHAPS), (i.e., requirements under sections 
111 and 112, respectively, of the Act), and a different SIP limitation, 
the more stringent limitation shall be used as the baseline for 
determining credit for emission and air quality offsets. The difference 
in emissions between the SIP and the NSPS or NESHAPS, for such source 
may not be used as offset credit. However, if a source were not subject 
to an NSPS or NESHAPS, for example if its construction had commenced 
prior to the proposal of an NSPS or NESHAPS for that source category, 
offset credit can be permitted for tightening the SIP to the NSPS or 
NESHAPS level for such source.
    D. Location of offsetting emissions. The owner or operator of a new 
or modified major stationary source may comply with any offset 
requirement in effect under this Ruling for increased emissions of any 
air pollutant only by obtaining emissions reductions of such air 
pollutant from the same source or other sources in the same 
nonattainment area, except that the reviewing authority may allow the 
owner or operator of a source

[[Page 588]]

to obtain such emissions reductions in another nonattainment area if the 
conditions in IV.D.1 and 2 are met.
    1. The other area has an equal or higher nonattainment 
classification than the area in which the source is located.
    2. Emissions from such other area contribute to a violation of the 
national ambient air quality standard in the nonattainment area in which 
the source is located.
    E. Reasonable further progress. Permits to construct and operate may 
be issued if the reviewing authority determines that, by the time the 
source is to commence operation, sufficient offsetting emissions 
reductions have been obtained, such that total allowable emissions from 
existing sources in the region, from new or modified sources which are 
not major emitting facilities, and from the proposed source will be 
sufficiently less than total emissions from existing sources prior to 
the application for such permit to construct or modify so as to 
represent (when considered together with the plan provisions required 
under CAA section 172) reasonable further progress (as defined in CAA 
section 171).
    F. Source obligation. At such time that a particular source or 
modification becomes a major stationary source or major modification 
solely by virtue of a relaxation in any enforceable limitation which was 
established after August 7, 1980, on the capacity of the source or 
modification otherwise to emit a pollutant, such as a restriction on 
hours of operation, then the requirements of this Ruling shall apply to 
the source or modification as though construction had not yet commenced 
on the source or modification.
    G. Offset Ratios.
    1. In meeting the emissions offset requirements of paragraph IV.A, 
Condition 3 of this Ruling, the ratio of total actual emissions 
reductions to the emissions increase shall be at least 1:1 unless an 
alternative ratio is provided for the applicable nonattainment area in 
paragraphs IV.G.2 through IV.G.4.
    2. In meeting the emissions offset requirements of paragraph IV.A, 
Condition 3 of this Ruling for ozone nonattainment areas that are 
subject to subpart 2, part D, title I of the Act, the ratio of total 
actual emissions reductions of VOC to the emissions increase of VOC 
shall be as follows:
    (i) In any marginal nonattainment area for ozone--at least 1.1:1;
    (ii) In any moderate nonattainment area for ozone--at least 1.15:1;
    (iii) In any serious nonattainment area for ozone--at least 1.2:1;
    (iv) In any severe nonattainment area for ozone--at least 1.3:1 
(except that the ratio may be at least 1.2:1 if the State also requires 
all existing major sources in such nonattainment area to use BACT for 
the control of VOC); and
    (v) In any extreme nonattainment area for ozone--at least 1.5:1 
(except that the ratio may be at least 1.2:1 if the State also requires 
all existing major sources in such nonattainment area to use BACT for 
the control of VOC); and
    3. Notwithstanding the requirements of paragraph IV.G.2 of this 
Ruling for meeting the requirements of paragraph IV.A, Condition 3 of 
this Ruling, the ratio of total actual emissions reductions of VOC to 
the emissions increase of VOC shall be at least 1.15:1 for all areas 
within an ozone transport region that is subject to subpart 2, part D, 
title I of the Act, except for serious, severe, and extreme ozone 
nonattainment areas that are subject to subpart 2, part D, title I of 
the Act.
    4. In meeting the emissions offset requirements of paragraph IV.A, 
Condition 3 of this Ruling for ozone nonattainment areas that are 
subject to subpart 1, part D, title I of the Act (but are not subject to 
subpart 2, part D, title I of the Act, including 8-hour ozone 
nonattainment areas subject to 40 CFR 51.902(b)), the ratio of total 
actual emissions reductions of VOC to the emissions increase of VOC 
shall be at least 1:1.
    5. Interpollutant offsetting, or interpollutant trading or 
interprecursor trading or interprecursor offset substitution. In meeting 
the emissions offset requirements of paragraph IV.A, Condition 3 of this 
Ruling, the emissions offsets obtained shall be for the same regulated 
nonattainment NSR pollutant unless interprecursor offsetting is 
permitted for a particular pollutant as specified in this paragraph 
IV.G.5 and the reviewing authority chooses to review such trading on a 
case by case basis as described in this section.
    (i) A reviewing authority may choose to satisfy the offset 
requirements of paragraph IV.A, Condition 3 of this Ruling for emissions 
of the ozone precursors NOX and VOC by offsetting reductions 
of emissions of either precursor, if all other requirements contained in 
this Ruling for such offsets are also satisfied. For a specific permit 
application, if the implementation of IPT is acceptable by the reviewing 
authority, the permit applicant shall submit to the reviewing authority 
for approval a case-specific permit IPT ratio for determining the 
required amount of emissions reductions to offset the proposed emissions 
increase when considered along with the applicable offset ratio as 
specified in paragraphs IV.G.2 through 4 of this Ruling. As part of the 
ratio submittal, the applicant shall submit the proposed permit-specific 
ozone IPT ratio to the reviewing authority, accompanied by the following 
information:
    (a) A description of the air quality model(s) that were used to 
propose a case-specific ratio; and

[[Page 589]]

    (b) The proposed ratio for the precursor substitution and 
accompanying calculations; and
    (c) A modeling demonstration showing that such ratio(s) as applied 
to the proposed project and credit source will provide an equivalent or 
greater air quality benefit with respect to ground level concentrations 
in the ozone nonattainment area than an offset of the emitted precursor 
would achieve.
    (ii) The offset requirements of paragraph IV.A, Condition 3 of this 
Ruling for direct PM2.5 emissions or emissions of precursors 
of PM2.5 may be satisfied by offsetting reductions of direct 
PM2.5 emissions or emissions of any PM2.5 
precursor identified under paragraph II.A.31 (iii) of this Ruling if 
such offsets comply with an interprecursor trading hierarchy and ratio 
approved by the Administrator.
    H. Additional provisions for emissions of nitrogen oxides in ozone 
transport regions and nonattainment areas. The requirements of this 
Ruling applicable to major stationary sources and major modifications of 
volatile organic compounds shall apply to nitrogen oxides emissions from 
major stationary sources and major modifications of nitrogen oxides in 
an ozone transport region or in any ozone nonattainment area, except in 
ozone nonattainment areas where the Administrator has granted a 
NOX waiver applying the standards set forth under 182(f) and 
the waiver continues to apply.
    I. Applicability procedures.
    1. To determine whether a project constitutes a major modification, 
the reviewing authority shall apply the principles set out in paragraphs 
IV.I.1(i) through (v) of this Ruling.
    (i) Except as otherwise provided in paragraph IV.I.2 of this Ruling, 
and consistent with the definition of major modification contained in 
paragraph II.A.5 of this Ruling, a project is a major modification for a 
regulated NSR pollutant if it causes two types of emissions increases--a 
significant emissions increase (as defined in paragraph II.A.23 of this 
Ruling), and a significant net emissions increase (as defined in 
paragraphs II.A.6 and 10 of this Ruling). The project is not a major 
modification if it does not cause a significant emissions increase. If 
the project causes a significant emissions increase, then the project is 
a major modification only if it also results in a significant net 
emissions increase.
    (ii) The procedure for calculating (before beginning actual 
construction) whether a significant emissions increase (i.e., the first 
step of the process) will occur depends upon the type of emissions units 
being modified, according to paragraphs IV.I.1(iii) through (v) of this 
Ruling. The procedure for calculating (before beginning actual 
construction) whether a significant net emissions increase will occur at 
the major stationary source (i.e., the second step of the process) is 
contained in the definition in paragraph II.A.6 of this Ruling. 
Regardless of any such preconstruction projections, a major modification 
results if the project causes a significant emissions increase and a 
significant net emissions increase.
    (iii) Actual-to-projected-actual applicability test for projects 
that only involve existing emissions units. A significant emissions 
increase of a regulated NSR pollutant is projected to occur if the sum 
of the difference between the projected actual emissions (as defined in 
paragraph II.A.24 of this Ruling) and the baseline actual emissions (as 
defined in paragraphs II.A.30(i) and (ii) of this Ruling, as 
applicable), for each existing emissions unit, equals or exceeds the 
significant amount for that pollutant (as defined in paragraph II.A.10 
of this Ruling).
    (iv) Actual-to-potential test for projects that only involve 
construction of a new emissions unit(s). A significant emissions 
increase of a regulated NSR pollutant is projected to occur if the sum 
of the difference between the potential to emit (as defined in paragraph 
II.A.3 of this Ruling) from each new emissions unit following completion 
of the project and the baseline actual emissions (as defined in 
paragraph II.A.30(iii) of this Ruling) of these units before the project 
equals or exceeds the significant amount for that pollutant (as defined 
in paragraph II.A.10 of this Ruling).
    (v) Hybrid test for projects that involve multiple types of 
emissions units. A significant emissions increase of a regulated NSR 
pollutant is projected to occur if the sum of the difference for all 
emissions units, using the method specified in paragraphs IV.I.1(iii) 
through (iv) of this Ruling as applicable with respect to each emissions 
unit, equals or exceeds the significant amount for that pollutant (as 
defined in paragraph II.A.10 of this Ruling).
    (vi) The ``sum of the difference'' as used in paragraphs (iii), (iv) 
and (v) of this section shall include both increases and decreases in 
emissions calculated in accordance with those paragraphs.
    2. For any major stationary source for a PAL for a regulated NSR 
pollutant, the major stationary source shall comply with requirements 
under paragraph IV.K of this Ruling.
    J. Provisions for projected actual emissions. Except as otherwise 
provided in paragraph IV.J.6(ii) of this Ruling, the provisions of this 
paragraph IV.J apply with respect to any regulated NSR pollutant emitted 
from projects at existing emissions units at a major stationary source 
(other than projects at a source with a PAL) in circumstances where 
there is a reasonable possibility, within the meaning of paragraph 
IV.J.6 of this Ruling, that a project that is not a part of a

[[Page 590]]

major modification may result in a significant emissions increase of 
such pollutant, and the owner or operator elects to use the method 
specified in paragraphs II.A.24(ii)(a) through (c) of this Ruling for 
calculating projected actual emissions.
    1. Before beginning actual construction of the project, the owner or 
operator shall document and maintain a record of the following 
information:
    (i) A description of the project;
    (ii) Identification of the emissions unit(s) whose emissions of a 
regulated NSR pollutant could be affected by the project; and
    (iii) A description of the applicability test used to determine that 
the project is not a major modification for any regulated NSR pollutant, 
including the baseline actual emissions, the projected actual emissions, 
the amount of emissions excluded under paragraph II.A.24(ii)(c) of this 
Ruling and an explanation for why such amount was excluded, and any 
netting calculations, if applicable.
    2. If the emissions unit is an existing electric utility steam 
generating unit, before beginning actual construction, the owner or 
operator shall provide a copy of the information set out in paragraph 
IV.J.1 of this Ruling to the reviewing authority. Nothing in this 
paragraph IV.J.2 shall be construed to require the owner or operator of 
such a unit to obtain any determination from the reviewing authority 
before beginning actual construction.
    3. The owner or operator shall monitor the emissions of any 
regulated NSR pollutant that could increase as a result of the project 
and that is emitted by any emissions units identified in paragraph 
IV.J.1(ii) of this Ruling; and calculate and maintain a record of the 
annual emissions, in tons per year on a calendar year basis, for a 
period of 5 years following resumption of regular operations after the 
change, or for a period of 10 years following resumption of regular 
operations after the change if the project increases the design capacity 
or potential to emit of that regulated NSR pollutant at such emissions 
unit.
    4. If the unit is an existing electric utility steam generating 
unit, the owner or operator shall submit a report to the reviewing 
authority within 60 days after the end of each year, during which 
records must be generated under paragraph IV.J.3 of this Ruling setting 
out the unit's annual emissions during the year that preceded submission 
of the report.
    5. If the unit is an existing unit other than an electric utility 
steam generating unit, the owner or operator shall submit a report to 
the reviewing authority if the annual emissions, in tons per year, from 
the project identified in paragraph IV.J.1 of this Ruling, exceed the 
baseline actual emissions (as documented and maintained pursuant to 
paragraph IV.J.1(iii) of this Ruling) by a significant amount (as 
defined in paragraph II.A.10 of this Ruling) for that regulated NSR 
pollutant, and if such emissions differ from the preconstruction 
projection as documented and maintained pursuant to paragraph 
IV.J.1(iii) of this Ruling. Such report shall be submitted to the 
reviewing authority within 60 days after the end of such year. The 
report shall contain the following:
    (i) The name, address and telephone number of the major stationary 
source;
    (ii) The annual emissions as calculated pursuant to paragraph IV.J.3 
of this Ruling; and
    (iii) Any other information that the owner or operator wishes to 
include in the report (e.g., an explanation as to why the emissions 
differ from the preconstruction projection).
    6. A ``reasonable possibility'' under paragraph IV.J of this Ruling 
occurs when the owner or operator calculates the project to result in 
either:
    (i) A projected actual emissions increase of at least 50 percent of 
the amount that is a ``significant emissions increase,'' as defined 
under paragraph II.A.23 of this Ruling (without reference to the amount 
that is a significant net emissions increase), for the regulated NSR 
pollutant; or
    (ii) A projected actual emissions increase that, added to the amount 
of emissions excluded under paragraph II.A.24(ii)(c), sums to at least 
50 percent of the amount that is a ``significant emissions increase,'' 
as defined under paragraph II.A.23 of this Ruling (without reference to 
the amount that is a significant net emissions increase), for the 
regulated NSR pollutant. For a project for which a reasonable 
possibility occurs only within the meaning of paragraph IV.J.6(ii) of 
this Ruling, and not also within the meaning of paragraph IV.J.6(i) of 
this Ruling, then provisions IV.J.2 through IV.J.5 do not apply to the 
project.
    7. The owner or operator of the source shall make the information 
required to be documented and maintained pursuant to this paragraph IV.J 
of this Ruling available for review upon a request for inspection by the 
reviewing authority or the general public pursuant to the requirements 
contained in Sec. 70.4(b)(3)(viii) of this chapter.
    K. Actuals PALs. The provisions in paragraphs IV.K.1 through 15 of 
this Ruling govern actuals PALs.
    1. Applicability.
    (i) The reviewing authority may approve the use of an actuals PAL 
for any existing major stationary source (except as provided in 
paragraph IV.K.1(ii) of this Ruling) if the PAL meets the requirements 
in paragraphs IV.K.1 through 15 of this Ruling. The term ``PAL'' shall 
mean ``actuals PAL'' throughout paragraph IV.K of this Ruling.
    (ii) The reviewing authority shall not allow an actuals PAL for VOC 
or NOX for any

[[Page 591]]

major stationary source located in an extreme ozone nonattainment area.
    (iii) Any physical change in or change in the method of operation of 
a major stationary source that maintains its total source-wide emissions 
below the PAL level, meets the requirements in paragraphs IV.K.1 through 
15 of this Ruling, and complies with the PAL permit:
    (a) Is not a major modification for the PAL pollutant;
    (b) Does not have to be approved through a nonattainment major NSR 
program; and
    (c) Is not subject to the provisions in paragraph IV.F of this 
Ruling (restrictions on relaxing enforceable emission limitations that 
the major stationary source used to avoid applicability of a 
nonattainment major NSR program).
    (iv) Except as provided under paragraph IV.K.1(iii)(c) of this 
Ruling, a major stationary source shall continue to comply with all 
applicable Federal or State requirements, emission limitations, and work 
practice requirements that were established prior to the effective date 
of the PAL.
    2. Definitions. For the purposes of this paragraph IV.K, the 
definitions in paragraphs IV.K.2(i) through (xi) of this Ruling apply. 
When a term is not defined in these paragraphs, it shall have the 
meaning given in paragraph II.A of this Ruling or in the Act.
    (i) Actuals PAL for a major stationary source means a PAL based on 
the baseline actual emissions (as defined in paragraph II.A.30 of this 
Ruling) of all emissions units (as defined in paragraph II.A.7 of this 
Ruling) at the source, that emit or have the potential to emit the PAL 
pollutant.
    (ii) Allowable emissions means ``allowable emissions'' as defined in 
paragraph II.A.11 of this Ruling, except as this definition is modified 
according to paragraphs IV.K.2(ii)(a) through (b) of this Ruling.
    (a) The allowable emissions for any emissions unit shall be 
calculated considering any emission limitations that are enforceable as 
a practical matter on the emissions unit's potential to emit.
    (b) An emissions unit's potential to emit shall be determined using 
the definition in paragraph II.A.3 of this Ruling, except that the words 
``enforceable as a practical matter'' should be added after ``federally 
enforceable.''
    (iii) Small emissions unit means an emissions unit that emits or has 
the potential to emit the PAL pollutant in an amount less than the 
significant level for that PAL pollutant, as defined in paragraph 
II.A.10 of this Ruling or in the Act, whichever is lower.
    (iv) Major emissions unit means:
    (a) Any emissions unit that emits or has the potential to emit 100 
tons per year or more of the PAL pollutant in an attainment area; or
    (b) Any emissions unit that emits or has the potential to emit the 
PAL pollutant in an amount that is equal to or greater than the major 
source threshold for the PAL pollutant as defined by the Act for 
nonattainment areas. For example, in accordance with the definition of 
major stationary source in section 182(c) of the Act, an emissions unit 
would be a major emissions unit for VOC if the emissions unit is located 
in a serious ozone nonattainment area and it emits or has the potential 
to emit 50 or more tons of VOC per year.
    (v) Plantwide applicability limitation (PAL) means an emission 
limitation expressed in tons per year, for a pollutant at a major 
stationary source, that is enforceable as a practical matter and 
established source-wide in accordance with paragraphs IV.K.1 through 15 
of this Ruling.
    (vi) PAL effective date generally means the date of issuance of the 
PAL permit. However, the PAL effective date for an increased PAL is the 
date any emissions unit which is part of the PAL major modification 
becomes operational and begins to emit the PAL pollutant.
    (vii) PAL effective period means the period beginning with the PAL 
effective date and ending 10 years later.
    (viii) PAL major modification means, notwithstanding paragraphs 
II.A.5 and 6 of this Ruling (the definitions for major modification and 
net emissions increase), any physical change in or change in the method 
of operation of the PAL source that causes it to emit the PAL pollutant 
at a level equal to or greater than the PAL.
    (ix) PAL permit means the permit issued under this Ruling, the major 
NSR permit, the minor NSR permit, or the State operating permit under a 
program that is approved into the plan, or the title V permit issued by 
the reviewing authority that establishes a PAL for a major stationary 
source.
    (x) PAL pollutant means the pollutant for which a PAL is established 
at a major stationary source.
    (xi) Significant emissions unit means an emissions unit that emits 
or has the potential to emit a PAL pollutant in an amount that is equal 
to or greater than the significant level (as defined in paragraph 
II.A.10 of this Ruling or in the Act, whichever is lower) for that PAL 
pollutant, but less than the amount that would qualify the unit as a 
major emissions unit as defined in paragraph IV.K.2(iv) of this Ruling.
    3. Permit application requirements. As part of a permit application 
requesting a PAL, the owner or operator of a major stationary source 
shall submit the following information to the reviewing authority for 
approval:
    (i) A list of all emissions units at the source designated as small, 
significant or major based on their potential to emit. In addition, the 
owner or operator of the source

[[Page 592]]

shall indicate which, if any, Federal or State applicable requirements, 
emission limitations or work practices apply to each unit.
    (ii) Calculations of the baseline actual emissions (with supporting 
documentation). Baseline actual emissions are to include emissions 
associated not only with operation of the unit, but also emissions 
associated with startup, shutdown and malfunction.
    (iii) The calculation procedures that the major stationary source 
owner or operator proposes to use to convert the monitoring system data 
to monthly emissions and annual emissions based on a 12-month rolling 
total for each month as required by paragraph IV.K.13(i) of this Ruling.
    4. General requirements for establishing PALs.
    (i) The reviewing authority is allowed to establish a PAL at a major 
stationary source, provided that at a minimum, the requirements in 
paragraphs IV.K.4(i) (a) through (g) of this Ruling are met.
    (a) The PAL shall impose an annual emission limitation in tons per 
year, that is enforceable as a practical matter, for the entire major 
stationary source. For each month during the PAL effective period after 
the first 12 months of establishing a PAL, the major stationary source 
owner or operator shall show that the sum of the monthly emissions from 
each emissions unit under the PAL for the previous 12 consecutive months 
is less than the PAL (a 12-month average, rolled monthly). For each 
month during the first 11 months from the PAL effective date, the major 
stationary source owner or operator shall show that the sum of the 
preceding monthly emissions from the PAL effective date for each 
emissions unit under the PAL is less than the PAL.
    (b) The PAL shall be established in a PAL permit that meets the 
public participation requirements in paragraph IV.K.5 of this Ruling.
    (c) The PAL permit shall contain all the requirements of paragraph 
IV.K.7 of this Ruling.
    (d) The PAL shall include fugitive emissions, to the extent 
quantifiable, from all emissions units that emit or have the potential 
to emit the PAL pollutant at the major stationary source.
    (e) Each PAL shall regulate emissions of only one pollutant.
    (f) Each PAL shall have a PAL effective period of 10 years.
    (g) The owner or operator of the major stationary source with a PAL 
shall comply with the monitoring, recordkeeping, and reporting 
requirements provided in paragraphs IV.K. 12 through 14 of this Ruling 
for each emissions unit under the PAL through the PAL effective period.
    (ii) At no time (during or after the PAL effective period) are 
emissions reductions of a PAL pollutant, which occur during the PAL 
effective period, creditable as decreases for purposes of offsets under 
paragraph IV.C of this Ruling unless the level of the PAL is reduced by 
the amount of such emissions reductions and such reductions would be 
creditable in the absence of the PAL.
    5. Public participation requirement for PALs. PALs for existing 
major stationary sources shall be established, renewed, or increased 
through a procedure that is consistent with ((51.160 and 51.161 of this 
chapter. This includes the requirement that the reviewing authority 
provide the public with notice of the proposed approval of a PAL permit 
and at least a 30-day period for submittal of public comment. The 
reviewing authority must address all material comments before taking 
final action on the permit.
    6. Setting the 10-year actuals PAL level. The actuals PAL level for 
a major stationary source shall be established as the sum of the 
baseline actual emissions (as defined in paragraph II.A.30 of this 
Ruling) of the PAL pollutant for each emissions unit at the source; plus 
an amount equal to the applicable significant level for the PAL 
pollutant under paragraph II.A.10 of this Ruling or under the Act, 
whichever is lower. When establishing the actuals PAL level, for a PAL 
pollutant, only one consecutive 24-month period must be used to 
determine the baseline actual emissions for all existing emissions 
units. However, a different consecutive 24-month period may be used for 
each different PAL pollutant. Emissions associated with units that were 
permanently shut down after this 24-month period must be subtracted from 
the PAL level. Emissions from units on which actual construction began 
after the 24-month period must be added to the PAL level in an amount 
equal to the potential to emit of the units. The reviewing authority 
shall specify a reduced PAL level(s) (in tons/yr) in the PAL permit to 
become effective on the future compliance date(s) of any applicable 
Federal or State regulatory requirement(s) that the reviewing authority 
is aware of prior to issuance of the PAL permit. For instance, if the 
source owner or operator will be required to reduce emissions from 
industrial boilers in half from baseline emissions of 60 ppm 
NOX to a new rule limit of 30 ppm, then the permit shall 
contain a future effective PAL level that is equal to the current PAL 
level reduced by half of the original baseline emissions of such 
unit(s).
    7. Contents of the PAL permit. The PAL permit contain, at a minimum, 
the information in paragraphs IV.K.7 (i) through (x) of this Ruling.
    (i) The PAL pollutant and the applicable source-wide emission 
limitation in tons per year.
    (ii) The PAL permit effective date and the expiration date of the 
PAL (PAL effective period).

[[Page 593]]

    (iii) Specification in the PAL permit that if a major stationary 
source owner or operator applies to renew a PAL in accordance with 
paragraph IV.K.10 of this Ruling before the end of the PAL effective 
period, then the PAL shall not expire at the end of the PAL effective 
period. It shall remain in effect until a revised PAL permit is issued 
by the reviewing authority.
    (iv) A requirement that emission calculations for compliance 
purposes include emissions from startups, shutdowns and malfunctions.
    (v) A requirement that, once the PAL expires, the major stationary 
source is subject to the requirements of paragraph IV.K.9 of this 
Ruling.
    (vi) The calculation procedures that the major stationary source 
owner or operator shall use to convert the monitoring system data to 
monthly emissions and annual emissions based on a 12-month rolling total 
for each month as required by paragraph IV.K.13(i) of this Ruling.
    (vii) A requirement that the major stationary source owner or 
operator monitor all emissions units in accordance with the provisions 
under paragraph IV.K.12 of this Ruling.
    (viii) A requirement to retain the records required under paragraph 
IV.K.13 of this Ruling on site. Such records may be retained in an 
electronic format.
    (ix) A requirement to submit the reports required under paragraph 
IV.K.14 of this Ruling by the required deadlines.
    (x) Any other requirements that the reviewing authority deems 
necessary to implement and enforce the PAL.
    8. PAL effective period and reopening of the PAL permit. The 
requirements in paragraphs IV.K.8(i) and (ii) of this Ruling apply to 
actuals PALs.
    (i) PAL effective period. The reviewing authority shall specify a 
PAL effective period of 10 years.
    (ii) Reopening of the PAL permit.
    (a) During the PAL effective period, the reviewing authority must 
reopen the PAL permit to:
    (1) Correct typographical/calculation errors made in setting the PAL 
or reflect a more accurate determination of emissions used to establish 
the PAL.
    (2) Reduce the PAL if the owner or operator of the major stationary 
source creates creditable emissions reductions for use as offsets under 
paragraph IV.C of this Ruling.
    (3) Revise the PAL to reflect an increase in the PAL as provided 
under paragraph IV.K.11 of this Ruling.
    (b) The reviewing authority shall have discretion to reopen the PAL 
permit for the following:
    (1) Reduce the PAL to reflect newly applicable Federal requirements 
(for example, NSPS) with compliance dates after the PAL effective date.
    (2) Reduce the PAL consistent with any other requirement, that is 
enforceable as a practical matter, and that the State may impose on the 
major stationary source under the plan.
    (3) Reduce the PAL if the reviewing authority determines that a 
reduction is necessary to avoid causing or contributing to a NAAQS or 
PSD increment violation, or to an adverse impact on an air quality 
related value that has been identified for a Federal Class I area by a 
Federal Land Manager and for which information is available to the 
general public.
    (c) Except for the permit reopening in paragraph IV.K.8(ii)(a)(1) of 
this Ruling for the correction of typographical/calculation errors that 
do not increase the PAL level, all other reopenings shall be carried out 
in accordance with the public participation requirements of paragraph 
IV.K.5 of this Ruling.
    9. Expiration of a PAL. Any PAL which is not renewed in accordance 
with the procedures in paragraph IV.K.10 of this Ruling shall expire at 
the end of the PAL effective period, and the requirements in paragraphs 
IV.K.9(i) through (v) of this Ruling shall apply.
    (i) Each emissions unit (or each group of emissions units) that 
existed under the PAL shall comply with an allowable emission limitation 
under a revised permit established according to the procedures in 
paragraphs IV.K.9(i)(a) through (b) of this Ruling.
    (a) Within the time frame specified for PAL renewals in paragraph 
IV.K.10(ii) of this Ruling, the major stationary source shall submit a 
proposed allowable emission limitation for each emissions unit (or each 
group of emissions units, if such a distribution is more appropriate as 
decided by the reviewing authority) by distributing the PAL allowable 
emissions for the major stationary source among each of the emissions 
units that existed under the PAL. If the PAL had not yet been adjusted 
for an applicable requirement that became effective during the PAL 
effective period, as required under paragraph IV.K.10(v) of this Ruling, 
such distribution shall be made as if the PAL had been adjusted.
    (b) The reviewing authority shall decide whether and how the PAL 
allowable emissions will be distributed and issue a revised permit 
incorporating allowable limits for each emissions unit, or each group of 
emissions units, as the reviewing authority determines is appropriate.
    (ii) Each emissions unit(s) shall comply with the allowable emission 
limitation on a 12-month rolling basis. The reviewing authority may 
approve the use of monitoring systems (source testing, emission factors, 
etc.) other than CEMS, CERMS, PEMS or

[[Page 594]]

CPMS to demonstrate compliance with the allowable emission limitation.
    (iii) Until the reviewing authority issues the revised permit 
incorporating allowable limits for each emissions unit, or each group of 
emissions units, as required under paragraph IV.K.9(i)(a) of this 
Ruling, the source shall continue to comply with a source-wide, multi-
unit emissions cap equivalent to the level of the PAL emission 
limitation.
    (iv) Any physical change or change in the method of operation at the 
major stationary source will be subject to the nonattainment major NSR 
requirements if such change meets the definition of major modification 
in paragraph II.A.5 of this Ruling.
    (v) The major stationary source owner or operator shall continue to 
comply with any State or Federal applicable requirements (BACT, RACT, 
NSPS, etc.) that may have applied either during the PAL effective period 
or prior to the PAL effective period except for those emission 
limitations that had been established pursuant to paragraph IV.F of this 
Ruling, but were eliminated by the PAL in accordance with the provisions 
in paragraph IV.K.1(iii)(c) of this Ruling.
    10. Renewal of a PAL.
    (i) The reviewing authority shall follow the procedures specified in 
paragraph IV.K.5 of this Ruling in approving any request to renew a PAL 
for a major stationary source, and shall provide both the proposed PAL 
level and a written rationale for the proposed PAL level to the public 
for review and comment. During such public review, any person may 
propose a PAL level for the source for consideration by the reviewing 
authority.
    (ii) Application deadline. The major stationary source owner or 
operator shall submit a timely application to the reviewing authority to 
request renewal of a PAL. A timely application is one that is submitted 
at least 6 months prior to, but not earlier than 18 months from, the 
date of permit expiration. This deadline for application submittal is to 
ensure that the permit will not expire before the permit is renewed. If 
the owner or operator of a major stationary source submits a complete 
application to renew the PAL within this time period, then the PAL shall 
continue to be effective until the revised permit with the renewed PAL 
is issued.
    (iii) Application requirements. The application to renew a PAL 
permit shall contain the information required in paragraphs 
IV.K.10(iii)(a) through (d) of this Ruling.
    (a) The information required in paragraphs IV.K.3(i) through (iii) 
of this Ruling.
    (b) A proposed PAL level.
    (c) The sum of the potential to emit of all emissions units under 
the PAL (with supporting documentation).
    (d) Any other information the owner or operator wishes the reviewing 
authority to consider in determining the appropriate level for renewing 
the PAL.
    (iv) PAL adjustment. In determining whether and how to adjust the 
PAL, the reviewing authority shall consider the options outlined in 
paragraphs IV.K.10(iv)(a) and (b) of this Ruling. However, in no case 
may any such adjustment fail to comply with paragraph IV.K.10(iv)(c) of 
this Ruling.
    (a) If the emissions level calculated in accordance with paragraph 
IV.K.6 of this Ruling is equal to or greater than 80 percent of the PAL 
level, the reviewing authority may renew the PAL at the same level 
without considering the factors set forth in paragraph IV.K.10(iv)(b) of 
this Ruling; or
    (b) The reviewing authority may set the PAL at a level that it 
determines to be more representative of the source's baseline actual 
emissions, or that it determines to be appropriate considering air 
quality needs, advances in control technology, anticipated economic 
growth in the area, desire to reward or encourage the source's voluntary 
emissions reductions, or other factors as specifically identified by the 
reviewing authority in its written rationale.
    (c) Notwithstanding paragraphs IV.K.10(iv)(a) and (b) of this 
Ruling,
    (1) If the potential to emit of the major stationary source is less 
than the PAL, the reviewing authority shall adjust the PAL to a level no 
greater than the potential to emit of the source; and
    (2) The reviewing authority shall not approve a renewed PAL level 
higher than the current PAL, unless the major stationary source has 
complied with the provisions of paragraph IV.K.11 of this Ruling 
(increasing a PAL).
    (v) If the compliance date for a State or Federal requirement that 
applies to the PAL source occurs during the PAL effective period, and if 
the reviewing authority has not already adjusted for such requirement, 
the PAL shall be adjusted at the time of PAL permit renewal or title V 
permit renewal, whichever occurs first.
    11. Increasing a PAL during the PAL effective period.
    (i) The reviewing authority may increase a PAL emission limitation 
only if the major stationary source complies with the provisions in 
paragraphs IV.K.11(i)(a) through (d) of this Ruling.
    (a) The owner or operator of the major stationary source shall 
submit a complete application to request an increase in the PAL limit 
for a PAL major modification. Such application shall identify the 
emissions unit(s) contributing to the increase in emissions so as to 
cause the major stationary source's emissions to equal or exceed its 
PAL.
    (b) As part of this application, the major stationary source owner 
or operator shall

[[Page 595]]

demonstrate that the sum of the baseline actual emissions of the small 
emissions units, plus the sum of the baseline actual emissions of the 
significant and major emissions units assuming application of BACT 
equivalent controls, plus the sum of the allowable emissions of the new 
or modified emissions unit(s) exceeds the PAL. The level of control that 
would result from BACT equivalent controls on each significant or major 
emissions unit shall be determined by conducting a new BACT analysis at 
the time the application is submitted, unless the emissions unit is 
currently required to comply with a BACT or LAER requirement that was 
established within the preceding 10 years. In such a case, the assumed 
control level for that emissions unit shall be equal to the level of 
BACT or LAER with which that emissions unit must currently comply.
    (c) The owner or operator obtains a major NSR permit for all 
emissions unit(s) identified in paragraph IV.K.11(i)(a) of this Ruling, 
regardless of the magnitude of the emissions increase resulting from 
them (that is, no significant levels apply). These emissions unit(s) 
shall comply with any emissions requirements resulting from the 
nonattainment major NSR program process (for example, LAER), even though 
they have also become subject to the PAL or continue to be subject to 
the PAL.
    (d) The PAL permit shall require that the increased PAL level shall 
be effective on the day any emissions unit that is part of the PAL major 
modification becomes operational and begins to emit the PAL pollutant.
    (ii) The reviewing authority shall calculate the new PAL as the sum 
of the allowable emissions for each modified or new emissions unit, plus 
the sum of the baseline actual emissions of the significant and major 
emissions units (assuming application of BACT equivalent controls as 
determined in accordance with paragraph IV.K.11(i)(b)), plus the sum of 
the baseline actual emissions of the small emissions units.
    (iii) The PAL permit shall be revised to reflect the increased PAL 
level pursuant to the public notice requirements of paragraph IV.K.5 of 
this Ruling.
    12. Monitoring requirements for PALs.
    (i) General Requirements.
    (a) Each PAL permit must contain enforceable requirements for the 
monitoring system that accurately determines plantwide emissions of the 
PAL pollutant in terms of mass per unit of time. Any monitoring system 
authorized for use in the PAL permit must be based on sound science and 
meet generally acceptable scientific procedures for data quality and 
manipulation. Additionally, the information generated by such system 
must meet minimum legal requirements for admissibility in a judicial 
proceeding to enforce the PAL permit.
    (b) The PAL monitoring system must employ one or more of the four 
general monitoring approaches meeting the minimum requirements set forth 
in paragraphs IV.K.12(ii)(a) through (d) of this Ruling and must be 
approved by the reviewing authority.
    (c) Notwithstanding paragraph IV.K.12(i)(b) of this Ruling, you may 
also employ an alternative monitoring approach that meets paragraph 
IV.K.12(i)(a) of this Ruling if approved by the reviewing authority.
    (d) Failure to use a monitoring system that meets the requirements 
of this Ruling renders the PAL invalid.
    (ii) Minimum Performance Requirements for Approved Monitoring 
Approaches. The following are acceptable general monitoring approaches 
when conducted in accordance with the minimum requirements in paragraphs 
IV.K.12(iii) through (ix) of this Ruling:
    (a) Mass balance calculations for activities using coatings or 
solvents;
    (b) CEMS;
    (c) CPMS or PEMS; and
    (d) Emission Factors.
    (iii) Mass Balance Calculations. An owner or operator using mass 
balance calculations to monitor PAL pollutant emissions from activities 
using coating or solvents shall meet the following requirements:
    (a) Provide a demonstrated means of validating the published content 
of the PAL pollutant that is contained in or created by all materials 
used in or at the emissions unit;
    (b) Assume that the emissions unit emits all of the PAL pollutant 
that is contained in or created by any raw material or fuel used in or 
at the emissions unit, if it cannot otherwise be accounted for in the 
process; and
    (c) Where the vendor of a material or fuel, which is used in or at 
the emissions unit, publishes a range of pollutant content from such 
material, the owner or operator must use the highest value of the range 
to calculate the PAL pollutant emissions unless the reviewing authority 
determines there is site-specific data or a site-specific monitoring 
program to support another content within the range.
    (iv) CEMS. An owner or operator using CEMS to monitor PAL pollutant 
emissions shall meet the following requirements:
    (a) CEMS must comply with applicable Performance Specifications 
found in 40 CFR part 60, appendix B; and
    (b) CEMS must sample, analyze and record data at least every 15 
minutes while the emissions unit is operating.
    (v) CPMS or PEMS. An owner or operator using CPMS or PEMS to monitor 
PAL pollutant emissions shall meet the following requirements:
    (a) The CPMS or the PEMS must be based on current site-specific data 
demonstrating a

[[Page 596]]

correlation between the monitored parameter(s) and the PAL pollutant 
emissions across the range of operation of the emissions unit; and
    (b) Each CPMS or PEMS must sample, analyze, and record data at least 
every 15 minutes, or at another less frequent interval approved by the 
reviewing authority, while the emissions unit is operating.
    (vi) Emission factors. An owner or operator using emission factors 
to monitor PAL pollutant emissions shall meet the following 
requirements:
    (a) All emission factors shall be adjusted, if appropriate, to 
account for the degree of uncertainty or limitations in the factors' 
development;
    (b) The emissions unit shall operate within the designated range of 
use for the emission factor, if applicable; and
    (c) If technically practicable, the owner or operator of a 
significant emissions unit that relies on an emission factor to 
calculate PAL pollutant emissions shall conduct validation testing to 
determine a site-specific emission factor within 6 months of PAL permit 
issuance, unless the reviewing authority determines that testing is not 
required.
    (vii) A source owner or operator must record and report maximum 
potential emissions without considering enforceable emission limitations 
or operational restrictions for an emissions unit during any period of 
time that there is no monitoring data, unless another method for 
determining emissions during such periods is specified in the PAL 
permit.
    (viii) Notwithstanding the requirements in paragraphs IV.K.12(iii) 
through (vii) of this Ruling, where an owner or operator of an emissions 
unit cannot demonstrate a correlation between the monitored parameter(s) 
and the PAL pollutant emissions rate at all operating points of the 
emissions unit, the reviewing authority shall, at the time of permit 
issuance:
    (a) Establish default value(s) for determining compliance with the 
PAL based on the highest potential emissions reasonably estimated at 
such operating point(s); or
    (b) Determine that operation of the emissions unit during operating 
conditions when there is no correlation between monitored parameter(s) 
and the PAL pollutant emissions is a violation of the PAL.
    (ix) Re-validation. All data used to establish the PAL pollutant 
must be re-validated through performance testing or other scientifically 
valid means approved by the reviewing authority. Such testing must occur 
at least once every 5 years after issuance of the PAL.
    13. Recordkeeping requirements.
    (i) The PAL permit shall require an owner or operator to retain a 
copy of all records necessary to determine compliance with any 
requirement of paragraph IV.K of this Ruling and of the PAL, including a 
determination of each emissions unit's 12-month rolling total emissions, 
for 5 years from the date of such record.
    (ii) The PAL permit shall require an owner or operator to retain a 
copy of the following records for the duration of the PAL effective 
period plus 5 years:
    (a) A copy of the PAL permit application and any applications for 
revisions to the PAL; and
    (b) Each annual certification of compliance pursuant to title V and 
the data relied on in certifying the compliance.
    14. Reporting and notification requirements. The owner or operator 
shall submit semi-annual monitoring reports and prompt deviation reports 
to the reviewing authority in accordance with the applicable title V 
operating permit program. The reports shall meet the requirements in 
paragraphs IV.K.14(i) through (iii).
    (i) Semi-Annual Report. The semi-annual report shall be submitted to 
the reviewing authority within 30 days of the end of each reporting 
period. This report shall contain the information required in paragraphs 
IV.K.14(i)(a) through (g) of this Ruling.
    (a) The identification of owner and operator and the permit number.
    (b) Total annual emissions (tons/year) based on a 12-month rolling 
total for each month in the reporting period recorded pursuant to 
paragraph IV.K.13(i) of this Ruling.
    (c) All data relied upon, including, but not limited to, any Quality 
Assurance or Quality Control data, in calculating the monthly and annual 
PAL pollutant emissions.
    (d) A list of any emissions units modified or added to the major 
stationary source during the preceding 6-month period.
    (e) The number, duration, and cause of any deviations or monitoring 
malfunctions (other than the time associated with zero and span 
calibration checks), and any corrective action taken.
    (f) A notification of a shutdown of any monitoring system, whether 
the shutdown was permanent or temporary, the reason for the shutdown, 
the anticipated date that the monitoring system will be fully 
operational or replaced with another monitoring system, and whether the 
emissions unit monitored by the monitoring system continued to operate, 
and the calculation of the emissions of the pollutant or the number 
determined by method included in the permit, as provided by paragraph 
IV.K.12(vii) of this Ruling.
    (g) A signed statement by the responsible official (as defined by 
the applicable title V operating permit program) certifying the truth, 
accuracy, and completeness of the information provided in the report.
    (ii) Deviation report. The major stationary source owner or operator 
shall promptly submit reports of any deviations or exceedance of the PAL 
requirements, including periods

[[Page 597]]

where no monitoring is available. A report submitted pursuant to Sec. 
70.6(a)(3)(iii)(B) of this chapter shall satisfy this reporting 
requirement. The deviation reports shall be submitted within the time 
limits prescribed by the applicable program implementing Sec. 
70.6(a)(3)(iii)(B) of this chapter. The reports shall contain the 
following information:
    (a) The identification of owner and operator and the permit number;
    (b) The PAL requirement that experienced the deviation or that was 
exceeded;
    (c) Emissions resulting from the deviation or the exceedance; and
    (d) A signed statement by the responsible official (as defined by 
the applicable title V operating permit program) certifying the truth, 
accuracy, and completeness of the information provided in the report.
    (iii) Re-validation results. The owner or operator shall submit to 
the reviewing authority the results of any re-validation test or method 
within 3 months after completion of such test or method.
    15. Transition requirements.
    (i) No reviewing authority may issue a PAL that does not comply with 
the requirements in paragraphs IV.K.1 through 15 of this Ruling after 
the date that this Ruling becomes effective for the State in which the 
major stationary source is located.
    (ii) The reviewing authority may supersede any PAL which was 
established prior to the date that this Ruling becomes effective for the 
State in which the major stationary source is located with a PAL that 
complies with the requirements of paragraphs IV.K.1 through 15 of this 
Ruling.
    L. Severability. If any provision of this Ruling, or the application 
of such provision to any person or circumstance, is held invalid, the 
remainder of this Ruling, or the application of such provision to 
persons or circumstances other than those as to which it is held 
invalid, shall not be affected thereby.

                      V. Administrative Procedures

    The necessary emission offsets may be proposed either by the owner 
of the proposed source or by the local community or the State. The 
emission reduction committed to must be enforceable by authorized State 
and/or local agencies and under the Clean Air Act, and must be 
accomplished by the new source's start-up date. If emission reductions 
are to be obtained in a State that neighbors the State in which the new 
source is to be located, the emission reductions committed to must be 
enforceable by the neighboring State and/or local agencies and under the 
Clean Air Act. Where the new facility is a replacement for a facility 
that is being shut down in order to provide the necessary offsets, the 
reviewing authority may allow up to 180 days for shakedown of the new 
facility before the existing facility is required to cease operation.
    A. Source initiated emission offsets. A source may propose emission 
offsets which involve:
    (1) Reductions from sources controlled by the source owner (internal 
emission offsets); and/or (2) reductions from neighboring sources 
(external emission offsets). The source does not have to investigate all 
possible emission offsets. As long as the emission offsets obtained 
represent reasonable progress toward attainment, they will be 
acceptable. It is the reviewing authority's responsibility to assure 
that the emission offsets will be as effective as proposed by the 
source. An internal emission offset will be considered enforceable if it 
is made a SIP requirement by inclusion as a condition of the new source 
permit and the permit is forwarded to the appropriate EPA Regional 
Office. \7\ An external emission offset will not be enforceable unless 
the affected source(s) providing the emission reductions is subject to a 
new SIP requirement to ensure that its emissions will be reduced by a 
specified amount in a specified time. Thus, if the source(s) providing 
the emission reductions does not obtain the necessary reduction, it will 
be in violation of a SIP requirement and subject to enforcement action 
by EPA, the State and/or private parties.
---------------------------------------------------------------------------

    \7\ The emission offset will, therefore, be enforceable by EPA under 
section 113 as an applicable SIP requirement and will be enforceable by 
private parties under section 304 as an emission limitation.
---------------------------------------------------------------------------

    The form of the SIP revision may be a State or local regulation, 
operating permit condition, consent or enforcement order, or any other 
mechanism available to the State that is enforceable under the Clean Air 
Act. If a SIP revision is required, the public hearing on the revision 
may be substituted for the normal public comment procedure required for 
all major sources under 40 CFR 51.18. The formal publication of the SIP 
revision approval in the Federal Register need not appear before the 
source may proceed with construction. To minimize uncertainty that may 
be caused by these procedures, EPA will, if requested by the State, 
propose a SIP revision for public comment in the Federal Register 
concurrently with the State public hearing process. Of course, any major 
change in the final permit/SIP revision submitted by the State may 
require a reproposal by EPA.
    B. State or community initiated emission offsets. A State or 
community which desires that a source locate in its area may commit to 
reducing emissions from existing sources (including mobile sources) to 
sufficiently outweigh the impact of the new source and thus open the way 
for the new source. As with source-initiated emission offsets, the 
commitment must be something more than

[[Page 598]]

one-for-one. This commitment must be submitted as a SIP revision by the 
State.

            VI. Policy Where Attainment Dates have not Passed

    In some cases, the dates for attainment of primary standards 
specified in the SIP under section 110 have not yet passed due to a 
delay in the promulgation of a plan under this section of the Act. In 
addition the Act provides more flexibility with respect to the dates for 
attainment of secondary NAAQS than for primary standards. Rather than 
setting specific deadlines, section 110 requires secondary NAAQS to be 
achieved within a ``reasonable time''. Therefore, in some cases, the 
date for attainment of secondary standards specified in the SIP under 
section 110 may also not yet have passed. In such cases, a new source 
locating in an area designated in 40 CFR 81.300 et seq. as nonattainment 
(or, where section III of this Ruling is applicable, a new source that 
would cause or contribute to a NAAQS violation) may be exempt from the 
Conditions of section IV.A if the conditions in paragraphs VI.A through 
C are met.
    A. The new source meets the applicable SIP emission limitations.
    B. The new source will not interfere with the attainment date 
specified in the SIP under section 110 of the Act.
    C. The Administrator has determined that conditions A and B of this 
section are satisfied and such determination is published in the Federal 
Register.

                             VII. [Reserved]

[44 FR 3282, Jan. 16, 1979]

    Editorial Note: For Federal Register citations affecting appendix S 
to part 51, see the List of CFR Sections Affected, which appears in the 
Finding Aids section of the printed volume and at www.govinfo.gov.

    Effective Date Note: At 76 FR 17554, Mar. 30, 2011, part 51, 
appendix S, paragraph II.A.5 (vii) is stayed indefinitely.



                Sec. Appendixes T-U to Part 51 [Reserved]



Sec. Appendix V to Part 51--Criteria for Determining the Completeness of 
                            Plan Submissions

                              1.0. Purpose

    This appendix V sets forth the minimum criteria for determining 
whether a State implementation plan submitted for consideration by EPA 
is an official submission for purposes of review under Sec. 51.103.
    1.1 The EPA shall return to the submitting official any plan or 
revision thereof which fails to meet the criteria set forth in this 
appendix V, and request corrective action, identifying the component(s) 
absent or insufficient to perform a review of the submitted plan.
    1.2 The EPA shall inform the submitting official whether or not a 
plan submission meets the requirements of this appendix V within 60 days 
of EPA's receipt of the submittal, but no later than 6 months after the 
date by which the State was required to submit the plan or revision. If 
a completeness determination is not made by 6 months from receipt of a 
submittal, the submittal shall be deemed complete by operation of law on 
the date 6 months from receipt. A determination of completeness under 
this paragraph means that the submission is an official submission for 
purposes of Sec. 51.103.

                              2.0. Criteria

    The following shall be included in plan submissions for review by 
EPA:
    2.1. Administrative Materials
    (a) A formal signed, stamped, and dated letter of submittal from the 
Governor or his designee, requesting EPA approval of the plan or 
revision thereof (hereafter ``the plan''). If electing to submit a paper 
submission with a copy in electronic version, the submittal letter must 
verify that the electronic copy provided is an exact duplicate of the 
paper submission.
    (b) Evidence that the State has adopted the plan in the State code 
or body of regulations; or issued the permit, order, consent agreement 
(hereafter ``document'') in final form. That evidence shall include the 
date of adoption or final issuance as well as the effective date of the 
plan, if different from the adoption/issuance date.
    (c) Evidence that the State has the necessary legal authority under 
State law to adopt and implement the plan.
    (d) A copy of the actual regulation, or document submitted for 
approval and incorporation by reference into the plan, including 
indication of the changes made (such as redline/strikethrough) to the 
existing approved plan, where applicable. The submission shall include a 
copy of the official State regulation/document, signed, stamped, and 
dated by the appropriate State official indicating that it is fully 
enforceable by the State. The effective date of any regulation/document 
contained in the submission shall, whenever possible, be indicated in 
the regulation/document itself; otherwise the State should include a 
letter signed, stamped, and dated by the appropriate State official 
indicating the effective date. If the regulation/document provided by 
the State for approval and incorporation by reference into the plan is a 
copy of an existing publication, the State submission should, whenever 
possible, include a copy of the publication cover page and table of 
contents.
    (e) Evidence that the State followed all of the procedural 
requirements of the State's

[[Page 599]]

laws and constitution in conducting and completing the adoption/issuance 
of the plan.
    (f) Evidence that public notice was given of the proposed change 
consistent with procedures approved by EPA, including the date of 
publication of such notice.
    (g) Certification that public hearing(s) were held in accordance 
with the information provided in the public notice and the State's laws 
and constitution, if applicable and consistent with the public hearing 
requirements in 40 CFR 51.102.
    (h) Compilation of public comments and the State's response thereto.
    2.2. Technical Support
    (a) Identification of all regulated pollutants affected by the plan.
    (b) Identification of the locations of affected sources including 
the EPA attainment/nonattainment designation of the locations and the 
status of the attainment plan for the affected areas(s).
    (c) Quantification of the changes in plan allowable emissions from 
the affected sources; estimates of changes in current actual emissions 
from affected sources or, where appropriate, quantification of changes 
in actual emissions from affected sources through calculations of the 
differences between certain baseline levels and allowable emissions 
anticipated as a result of the revision.
    (d) The State's demonstration that the national ambient air quality 
standards, prevention of significant deterioration increments, 
reasonable further progress demonstration, and visibility, as 
applicable, are protected if the plan is approved and implemented. For 
all requests to redesignate an area to attainment for a national primary 
ambient air quality standard, under section 107 of the Act, a revision 
must be submitted to provide for the maintenance of the national primary 
ambient air quality standards for at least 10 years as required by 
section 175A of the Act.
    (e) Modeling information required to support the proposed revision, 
including input data, output data, models used, justification of model 
selections, ambient monitoring data used, meteorological data used, 
justification for use of offsite data (where used), modes of models 
used, assumptions, and other information relevant to the determination 
of adequacy of the modeling analysis.
    (f) Evidence, where necessary, that emission limitations are based 
on continuous emission reduction technology.
    (g) Evidence that the plan contains emission limitations, work 
practice standards and recordkeeping/reporting requirements, where 
necessary, to ensure emission levels.
    (h) Compliance/enforcement strategies, including how compliance will 
be determined in practice.
    (i) Special economic and technological justifications required by 
any applicable EPA policies, or an explanation of why such 
justifications are not necessary.
    2.3. Exceptions
    2.3.1. The EPA, for the purposes of expediting the review of the 
plan, has adopted a procedure referred to as ``parallel processing.'' 
Parallel processing allows a State to submit the plan prior to actual 
adoption by the State and provides an opportunity for the State to 
consider EPA comments prior to submission of a final plan for final 
review and action. Under these circumstances, the plan submitted will 
not be able to meet all of the requirements of paragraph 2.1 (all 
requirements of paragraph 2.2 will apply). As a result, the following 
exceptions apply to plans submitted explicitly for parallel processing:
    (a) The letter required by paragraph 2.1(a) shall request that EPA 
propose approval of the proposed plan by parallel processing.
    (b) In lieu of paragraph 2.1(b) the State shall submit a schedule 
for final adoption or issuance of the plan.
    (c) In lieu of paragraph 2.1(d) the plan shall include a copy of the 
proposed/draft regulation or document, including indication of the 
proposed changes to be made to the existing approved plan, where 
applicable.
    (d) The requirements of paragraphs 2.1(e)-2.1(h) shall not apply to 
plans submitted for parallel processing.
    2.3.2. The exceptions granted in paragraph 2.3.1 shall apply only to 
EPA's determination of proposed action and all requirements of paragraph 
2.1 shall be met prior to publication of EPA's final determination of 
plan approvability.

                             3.0. Guidelines

    The EPA requests that the State adhere to the following voluntary 
guidelines when making plan submissions.

                           3.1 All Submissions

    (a) The State should identify any copyrighted material in its 
submission, as EPA does not place such material on the web when creating 
the E-Docket for loading into the Federal Document Management System 
(FDMS).
    (b) The State is advised not to include any material considered 
Confidential Business Information (CBI) in their SIP submissions. In 
rare instances where such information is necessary to justify the 
control requirements and emissions limitations established in the plan, 
the State should confer with its Regional Offices prior to submission 
and must clearly identify such material as CBI in the submission itself. 
EPA does not place such material in any paper or web-based docket. 
However, where any such material is considered emissions data within the 
meaning of Section 114 of the CAA, it cannot be

[[Page 600]]

withheld as CBI and must be made publicly available.

                       3.2 Paper Plan Submissions

    (a) The EPA requires that the submission option of submitting one 
paper plan must be accompanied by an electronic duplicate of the entire 
paper submission, preferably as a word searchable portable document 
format (PDF), at the same time the paper copy is submitted. The 
electronic duplicate should be made available through email, from a File 
Transfer Protocol (FTP) site, from the State Web site, on a Universal 
Serial Bus (USB) flash drive, on a compact disk, or using another format 
agreed upon by the State and Regional Office.
    (b) If a state prefers the submission option of submitting three 
paper copies and has no means of making an electronic copy available to 
EPA, EPA requests that the state confer with its EPA Regional Office 
regarding additional guidelines for submitting the plan to EPA.

[55 FR 5830, Feb. 16, 1990, as amended at 56 FR 42219, Aug. 26, 1991; 56 
FR 57288, Nov. 8, 1991; 72 FR 38793, July 16, 2007; 80 FR 7340, Feb. 10, 
2015]



       Sec. Appendix W to Part 51--Guideline on Air Quality Models

                                 Preface

    a. Industry and control agencies have long expressed a need for 
consistency in the application of air quality models for regulatory 
purposes. In the 1977 Clean Air Act (CAA), Congress mandated such 
consistency and encouraged the standardization of model applications. 
The Guideline on Air Quality Models (hereafter, Guideline) was first 
published in April 1978 to satisfy these requirements by specifying 
models and providing guidance for their use. The Guideline provides a 
common basis for estimating the air quality concentrations of criteria 
pollutants used in assessing control strategies and developing emissions 
limits.
    b. The continuing development of new air quality models in response 
to regulatory requirements and the expanded requirements for models to 
cover even more complex problems have emphasized the need for periodic 
review and update of guidance on these techniques. Historically, three 
primary activities have provided direct input to revisions of the 
Guideline. The first is a series of periodic EPA workshops and modeling 
conferences conducted for the purpose of ensuring consistency and 
providing clarification in the application of models. The second 
activity was the solicitation and review of new models from the 
technical and user community. In the March 27, 1980, Federal Register, a 
procedure was outlined for the submittal to the EPA of privately 
developed models. After extensive evaluation and scientific review, 
these models, as well as those made available by the EPA, have been 
considered for recognition in the Guideline. The third activity is the 
extensive on-going research efforts by the EPA and others in air quality 
and meteorological modeling.
    c. Based primarily on these three activities, new sections and 
topics have been included as needed. The EPA does not make changes to 
the guidance on a predetermined schedule, but rather on an as-needed 
basis. The EPA believes that revisions of the Guideline should be timely 
and responsive to user needs and should involve public participation to 
the greatest possible extent. All future changes to the guidance will be 
proposed and finalized in the Federal Register. Information on the 
current status of modeling guidance can always be obtained from the 
EPA's Regional Offices.

                            Table of Contents

                             List of Tables

1.0 Introduction
2.0 Overview of Model Use
2.1 Suitability of Models
    2.1.1 Model Accuracy and Uncertainty
2.2 Levels of Sophistication of Air Quality Analyses and Models
2.3 Availability of Models
3.0 Preferred and Alternative Air Quality Models
3.1 Preferred Models
    3.1.1 Discussion
    3.1.2 Requirements
3.2 Alternative Models
    3.2.1 Discussion
    3.2.2 Requirements
3.3 EPA's Model Clearinghouse
4.0 Models for Carbon Monoxide, Lead, Sulfur Dioxide, Nitrogen Dioxide 
          and Primary Particulate Matter
4.1 Discussion
4.2 Requirements
    4.2.1 Screening Models and Techniques
    4.2.1.1 AERSCREEN
    4.2.1.2 CTSCREEN
    4.2.1.3 Screening in Complex Terrain
    4.2.2 Refined Models
    4.2.2.1 AERMOD
    4.2.2.2 CTDMPLUS
    4.2.2.3 OCD
    4.2.3 Pollutant Specific Modeling Requirements
    4.2.3.1 Models for Carbon Monoxide
    4.2.3.2 Models for Lead
    4.2.3.3 Models for Sulfur Dioxide
    4.2.3.4 Models for Nitrogen Dioxide
    4.2.3.5 Models for PM2.5
    4.2.3.6 Models for PM10
5.0 Models for Ozone and Secondarily Formed Particulate Matter
5.1 Discussion
5.2 Recommendations

[[Page 601]]

5.3 Recommended Models and Approaches for Ozone
    5.3.1 Models for NAAQS Attainment Demonstrations and Multi-Source 
Air Quality Assessments
    5.3.2 Models for Single-Source Air Quality Assessments
    5.4 Recommended Models and Approaches for Secondarily Formed 
PM2.5
    5.4.1 Models for NAAQS Attainment Demonstrations and Multi-Source 
Air Quality Assessments
    5.4.2 Models for Single-Source Air Quality Assessments
6.0 Modeling for Air Quality Related Values and Other Governmental 
          Programs
6.1 Discussion
6.2 Air Quality Related Values
    6.2.1 Visibility
    6.2.1.1 Models for Estimating Near-Field Visibility Impairment
    6.2.1.2 Models for Estimating Visibility Impairment for Long-Range 
Transport
    6.2.2 Models for Estimating Deposition Impacts
6.3 Modeling Guidance for Other Governmental Programs
7.0 General Modeling Considerations
7.1 Discussion
7.2 Recommendations
    7.2.1 All sources
    7.2.1.1 Dispersion Coefficients
    7.2.1.2 Complex Winds
    7.2.1.3 Gravitational Settling and Deposition
    7.2.2 Stationary Sources
    7.2.2.1 Good Engineering Practice Stack Height
    7.2.2.2 Plume Rise
    7.2.3 Mobile Sources
8.0 Model Input Data
8.1 Modeling Domain
    8.1.1 Discussion
    8.1.2 Requirements
8.2 Source Data
    8.2.1 Discussion
    8.2.2 Requirements
8.3 Background Concentrations
    8.3.1 Discussion
    8.3.2 Recommendations for Isolated Single Sources
    8.3.3 Recommendations for Multi-Source Areas
8.4 Meteorological Input Data
    8.4.1 Discussion
    8.4.2 Recommendations and Requirements
    8.4.3 National Weather Service Data
    8.4.3.1 Discussion
    8.4.3.2 Recommendations
    8.4.4 Site-specific data
    8.4.4.1 Discussion
    8.4.4.2 Recommendations
    8.4.5 Prognostic meteorological data
    8.4.5.1 Discussion
    8.4.5.2 Recommendations
    8.4.6 Treatment of Near-Calms and Calms
    8.4.6.1 Discussion
    8.4.6.2 Recommendations
9.0 Regulatory Application of Models
9.1 Discussion
9.2 Recommendations
    9.2.1 Modeling Protocol
    9.2.2 Design Concentration and Receptor Sites
    9.2.3 NAAQS and PSD Increments Compliance Demonstrations for New or 
Modified Sources
    9.2.3.1 Considerations in Developing Emissions Limits
    9.2.4 Use of Measured Data in Lieu of Model Estimates
10.0 References

Appendix A to Appendix W of Part 51--Summaries of Preferred Air Quality 
                                 Models

                             List of Tables

------------------------------------------------------------------------
             Table No.                              Title
------------------------------------------------------------------------
8-1...............................  Point Source Model Emission Inputs
                                     for SIP Revisions of Inert
                                     Pollutants.
8-2...............................  Point Source Model Emission Inputs
                                     for NAAQS Compliance in PSD
                                     Demonstrations.
------------------------------------------------------------------------

                            1.0 Introduction

    a. The Guideline provides air quality modeling techniques that 
should be applied to State Implementation Plan (SIP) submittals and 
revisions, to New Source Review (NSR), including new or modifying 
sources under Prevention of Significant Deterioration (PSD),\1 2 3\ 
conformity analyses,\4\ and other air quality assessments required under 
EPA regulation. Applicable only to criteria air pollutants, the 
Guideline is intended for use by the EPA Regional Offices in judging the 
adequacy of modeling analyses performed by the EPA, by state, local, and 
tribal permitting authorities, and by industry. It is appropriate for 
use by other federal government agencies and by state, local, and tribal 
agencies with air quality and land management responsibilities. The 
Guideline serves to identify, for all interested parties, those modeling 
techniques and databases that the EPA considers acceptable. The 
Guideline is not intended to be a compendium of modeling techniques. 
Rather, it should serve as a common measure of acceptable technical 
analysis when supported by sound scientific judgment.
    b. Air quality measurements \5\ are routinely used to characterize 
ambient concentrations of criteria pollutants throughout the nation but 
are rarely sufficient for characterizing the ambient impacts of 
individual sources or demonstrating adequacy of emissions limits for an 
existing source due to limitations in spatial and temporal coverage of 
ambient monitoring networks. The impacts of new sources that do not yet 
exist, and modifications to existing sources that

[[Page 602]]

have yet to be implemented, can only be determined through modeling. 
Thus, models have become a primary analytical tool in most air quality 
assessments. Air quality measurements can be used in a complementary 
manner to air quality models, with due regard for the strengths and 
weaknesses of both analysis techniques, and are particularly useful in 
assessing the accuracy of model estimates.
    c. It would be advantageous to categorize the various regulatory 
programs and to apply a designated model to each proposed source needing 
analysis under a given program. However, the diversity of the nation's 
topography and climate, and variations in source configurations and 
operating characteristics dictate against a strict modeling 
``cookbook.'' There is no one model capable of properly addressing all 
conceivable situations even within a broad category such as point 
sources. Meteorological phenomena associated with threats to air quality 
standards are rarely amenable to a single mathematical treatment; thus, 
case-by-case analysis and judgment are frequently required. As modeling 
efforts become more complex, it is increasingly important that they be 
directed by highly competent individuals with a broad range of 
experience and knowledge in air quality meteorology. Further, they 
should be coordinated closely with specialists in emissions 
characteristics, air monitoring and data processing. The judgment of 
experienced meteorologists, atmospheric scientists, and analysts is 
essential.
    d. The model that most accurately estimates concentrations in the 
area of interest is always sought. However, it is clear from the needs 
expressed by the EPA Regional Offices, by state, local, and tribal 
agencies, by many industries and trade associations, and also by the 
deliberations of Congress, that consistency in the selection and 
application of models and databases should also be sought, even in case-
by-case analyses. Consistency ensures that air quality control agencies 
and the general public have a common basis for estimating pollutant 
concentrations, assessing control strategies, and specifying emissions 
limits. Such consistency is not, however, promoted at the expense of 
model and database accuracy. The Guideline provides a consistent basis 
for selection of the most accurate models and databases for use in air 
quality assessments.
    e. Recommendations are made in the Guideline concerning air quality 
models and techniques, model evaluation procedures, and model input 
databases and related requirements. The guidance provided here should be 
followed in air quality analyses relative to SIPs, NSR, and in 
supporting analyses required by the EPA and by state, local, and tribal 
permitting authorities. Specific models are identified for particular 
applications. The EPA may approve the use of an alternative model or 
technique that can be demonstrated to be more appropriate than those 
recommended in the Guideline. In all cases, the model or technique 
applied to a given situation should be the one that provides the most 
accurate representation of atmospheric transport, dispersion, and 
chemical transformations in the area of interest. However, to ensure 
consistency, deviations from the Guideline should be carefully 
documented as part of the public record and fully supported by the 
appropriate reviewing authority, as discussed later.
    f. From time to time, situations arise requiring clarification of 
the intent of the guidance on a specific topic. Periodic workshops are 
held with EPA headquarters, EPA Regional Offices, and state, local, and 
tribal agency modeling representatives to ensure consistency in modeling 
guidance and to promote the use of more accurate air quality models, 
techniques, and databases. The workshops serve to provide further 
explanations of Guideline requirements to the EPA Regional Offices and 
workshop materials are issued with this clarifying information. In 
addition, findings from ongoing research programs, new model 
development, or results from model evaluations and applications are 
continuously evaluated. Based on this information, changes in the 
applicable guidance may be indicated and appropriate revisions to the 
Guideline may be considered.
    g. All changes to the Guideline must follow rulemaking requirements 
since the Guideline is codified in appendix W to 40 Code of Federal 
Regulations (CFR) part 51. The EPA will promulgate proposed and final 
rules in the Federal Register to amend this appendix. The EPA utilizes 
the existing procedures under CAA section 320 that requires the EPA to 
conduct a Conference on Air Quality Modeling at least every 3 years (CAA 
320, 42 U.S.C. 7620). These modeling conferences are intended to develop 
standardized air quality modeling procedures and form the basis for 
associated revisions to this Guideline in support of the EPA's 
continuing effort to prescribe with ``reasonable particularity'' air 
quality models and meteorological and emission databases suitable for 
modeling National Ambient Air Quality Standards (NAAQS) \6\ and PSD 
increments. Ample opportunity for public comment will be provided for 
each proposed change and public hearings scheduled.
    h. A wide range of topics on modeling and databases are discussed in 
the Guideline. Section 2 gives an overview of models and their 
suitability for use in regulatory applications. Section 3 provides 
specific guidance on the determination of preferred air quality models 
and on the selection of alternative models or techniques. Sections 4 
through 6 provide recommendations on modeling techniques for assessing 
criteria pollutant impacts from single and multiple sources with

[[Page 603]]

specific modeling requirements for selected regulatory applications. 
Section 7 discusses general considerations common to many modeling 
analyses for stationary and mobile sources. Section 8 makes 
recommendations for data inputs to models including source, background 
air quality, and meteorological data. Section 9 summarizes how estimates 
and measurements of air quality are used in assessing source impact and 
in evaluating control strategies.
    i. Appendix W to 40 CFR part 51 contains an appendix: Appendix A. 
Thus, when reference is made to ``appendix A'' in this document, it 
refers to appendix A to appendix W to 40 CFR part 51. Appendix A 
contains summaries of refined air quality models that are ``preferred'' 
for particular applications; both EPA models and models developed by 
others are included.

                        2.0 Overview of Model Use

    a. Increasing reliance has been placed on concentration estimates 
from air quality models as the primary basis for regulatory decisions 
concerning source permits and emission control requirements. In many 
situations, such as review of a proposed new source, no practical 
alternative exists. Before attempting to implement the guidance 
contained in this document, the reader should be aware of certain 
general information concerning air quality models and their evaluation 
and use. Such information is provided in this section.

                        2.1 Suitability of Models

    a. The extent to which a specific air quality model is suitable for 
the assessment of source impacts depends upon several factors. These 
include: (1) The topographic and meteorological complexities of the 
area; (2) the detail and accuracy of the input databases, i.e., 
emissions inventory, meteorological data, and air quality data; (3) the 
manner in which complexities of atmospheric processes are handled in the 
model; (4) the technical competence of those undertaking such simulation 
modeling; and (5) the resources available to apply the model. Any of 
these factors can have a significant influence on the overall model 
performance, which must be thoroughly evaluated to determine the 
suitability of an air quality model to a particular application or range 
of applications.
    b. Air quality models are most accurate and reliable in areas that 
have gradual transitions of land use and topography. Meteorological 
conditions in these areas are spatially uniform such that observations 
are broadly representative and air quality model projections are not 
further complicated by a heterogeneous environment. Areas subject to 
major topographic influences experience meteorological complexities that 
are often difficult to measure and simulate. Models with adequate 
performance are available for increasingly complex environments. 
However, they are resource intensive and frequently require site-
specific observations and formulations. Such complexities and the 
related challenges for the air quality simulation should be considered 
when selecting the most appropriate air quality model for an 
application.
    c. Appropriate model input data should be available before an 
attempt is made to evaluate or apply an air quality model. Assuming the 
data are adequate, the greater the detail with which a model considers 
the spatial and temporal variations in meteorological conditions and 
permit-enforceable emissions, the greater the ability to evaluate the 
source impact and to distinguish the effects of various control 
strategies.
    d. There are three types of models that have historically been used 
in the regulatory demonstrations applicable in the Guideline, each 
having strengths and weaknesses that lend themselves to particular 
regulatory applications.
    i. Gaussian plume models use a ``steady-state'' approximation, which 
assumes that over the model time step, the emissions, meteorology and 
other model inputs, are constant throughout the model domain, resulting 
in a resolved plume with the emissions distributed throughout the plume 
according to a Gaussian distribution. This formulation allows Gaussian 
models to estimate near-field impacts of a limited number of sources at 
a relatively high resolution, with temporal scales of an hour and 
spatial scales of meters. However, this formulation allows for only 
relatively inert pollutants, with very limited considerations of 
transformation and removal (e.g., deposition), and further limits the 
domain for which the model may be used. Thus, Gaussian models may not be 
appropriate if model inputs are changing sharply over the model time 
step or within the desired model domain, or if more advanced 
considerations of chemistry are needed.
    ii. Lagrangian puff models, on the other hand, are non-steady-state, 
and assume that model input conditions are changing over the model 
domain and model time step. Lagrangian models can also be used to 
determine near- and far-field impacts from a limited number of sources. 
Traditionally, Lagrangian models have been used for relatively inert 
pollutants, with slightly more complex considerations of removal than 
Gaussian models. Some Lagrangian models treat in-plume gas and 
particulate chemistry. However, these models require time and space 
varying concentration fields of oxidants and, in the case of fine 
particulate matter (PM2.5), neutralizing agents, such as 
ammonia. Reliable background fields are critical for applications 
involving secondary

[[Page 604]]

pollutant formation because secondary impacts generally occur when in-
plume precursors mix and react with species in the background 
atmosphere.\z7 8\ These oxidant and neutralizing agents are not 
routinely measured, but can be generated with a three-dimensional 
photochemical grid model.
    iii. Photochemical grid models are three-dimensional Eulerian grid-
based models that treat chemical and physical processes in each grid 
cell and use diffusion and transport processes to move chemical species 
between grid cells.\9\ Eulerian models assume that emissions are spread 
evenly throughout each model grid cell. At coarse grid resolutions, 
Eulerian models have difficulty with fine scale resolution of individual 
plumes. However, these types of models can be appropriately applied for 
assessment of near-field and regional scale reactive pollutant impacts 
from specific sources \7 10 11 12\ or all sources.\13 14 15\ 
Photochemical grid models simulate a more realistic environment for 
chemical transformation,\7 12\ but simulations can be more resource 
intensive than Lagrangian or Gaussian plume models.
    e. Competent and experienced meteorologists, atmospheric scientists, 
and analysts are an essential prerequisite to the successful application 
of air quality models. The need for such specialists is critical when 
sophisticated models are used or the area has complicated meteorological 
or topographic features. It is important to note that a model applied 
improperly or with inappropriate data can lead to serious misjudgments 
regarding the source impact or the effectiveness of a control strategy.
    f. The resource demands generated by use of air quality models vary 
widely depending on the specific application. The resources required may 
be important factors in the selection and use of a model or technique 
for a specific analysis. These resources depend on the nature of the 
model and its complexity, the detail of the databases, the difficulty of 
the application, the amount and level of expertise required, and the 
costs of manpower and computational facilities.

                  2.1.1 Model Accuracy and Uncertainty

    a. The formulation and application of air quality models are 
accompanied by several sources of uncertainty. ``Irreducible'' 
uncertainty stems from the ``unknown'' conditions, which may not be 
explicitly accounted for in the model (e.g., the turbulent velocity 
field). Thus, there are likely to be deviations from the observed 
concentrations in individual events due to variations in the unknown 
conditions. ``Reducible'' uncertainties \16\ are caused by: (1) 
Uncertainties in the ``known'' input conditions (e.g., emission 
characteristics and meteorological data); (2) errors in the measured 
concentrations; and (3) inadequate model physics and formulation.
    b. Evaluations of model accuracy should focus on the reducible 
uncertainty associated with physics and the formulation of the model. 
The accuracy of the model is normally determined by an evaluation 
procedure which involves the comparison of model concentration estimates 
with measured air quality data.\17\ The statement of model accuracy is 
based on statistical tests or performance measures such as bias, error, 
correlation, etc.\18 19\
    c. Since the 1980's, the EPA has worked with the modeling community 
to encourage development of standardized model evaluation methods and 
the development of continually improved methods for the characterization 
of model performance.16 18 20 21 22 
There is general consensus on what should be considered in the 
evaluation of air quality models; namely, quality assurance planning, 
documentation and scrutiny should be consistent with the intended use 
and should include:
     Scientific peer review;
     Supportive analyses (diagnostic evaluations, code 
verification, sensitivity analyses);
     Diagnostic and performance evaluations with data 
obtained in trial locations; and
     Statistical performance evaluations in the 
circumstances of the intended applications.

Performance evaluations and diagnostic evaluations assess different 
qualities of how well a model is performing, and both are needed to 
establish credibility within the client and scientific community.
    d. Performance evaluations allow the EPA and model users to 
determine the relative performance of a model in comparison with 
alternative modeling systems. Diagnostic evaluations allow determination 
of a model capability to simulate individual processes that affect the 
results, and usually employ smaller spatial/temporal scale data sets 
(e.g., field studies). Diagnostic evaluations enable the EPA and model 
users to build confidence that model predictions are accurate for the 
right reasons. However, the objective comparison of modeled 
concentrations with observed field data provides only a partial means 
for assessing model performance. Due to the limited supply of evaluation 
datasets, there are practical limits in assessing model performance. For 
this reason, the conclusions reached in the science peer reviews and the 
supportive analyses have particular relevance in deciding whether a 
model will be useful for its intended purposes.

     2.2 Levels of Sophistication of Air Quality Analyses and Models

    a. It is desirable to begin an air quality analysis by using 
simplified and conservative methods followed, as appropriate, by

[[Page 605]]

more complex and refined methods. The purpose of this approach is to 
streamline the process and sufficiently address regulatory requirements 
by eliminating the need of more detailed modeling when it is not 
necessary in a specific regulatory application. For example, in the 
context of a PSD permit application, a simplified and conservative 
analysis may be sufficient where it shows the proposed construction 
clearly will not cause or contribute to ambient concentrations in excess 
of either the NAAQS or the PSD increments.\2 3\
    b. There are two general levels of sophistication of air quality 
models. The first level consists of screening models that provide 
conservative modeled estimates of the air quality impact of a specific 
source or source category based on simplified assumptions of the model 
inputs (e.g., preset, worst-case meteorological conditions). In the case 
of a PSD assessment, if a screening model indicates that the increase in 
concentration attributable to the source could cause or contribute to a 
violation of any NAAQS or PSD increment, then the second level of more 
sophisticated models should be applied unless appropriate controls or 
operational restrictions are implemented based on the screening 
modeling.
    c. The second level consists of refined models that provide more 
detailed treatment of physical and chemical atmospheric processes, 
require more detailed and precise input data, and provide spatially and 
temporally resolved concentration estimates. As a result, they provide a 
more sophisticated and, at least theoretically, a more accurate estimate 
of source impact and the effectiveness of control strategies.
    d. There are situations where a screening model or a refined model 
is not available such that screening and refined modeling are not viable 
options to determine source-specific air quality impacts. In such 
situations, a screening technique or reduced-form model may be viable 
options for estimating source impacts.
    i. Screening techniques are differentiated from a screening model in 
that screening techniques are approaches that make simplified and 
conservative assumptions about the physical and chemical atmospheric 
processes important to determining source impacts, while screening 
models make assumptions about conservative inputs to a specific model. 
The complexity of screening techniques ranges from simplified 
assumptions of chemistry applied to refined or screening model output to 
sophisticated approximations of the chemistry applied within a refined 
model.
    ii. Reduced-form models are computationally efficient simulation 
tools for characterizing the pollutant response to specific types of 
emission reductions for a particular geographic area or background 
environmental conditions that reflect underlying atmospheric science of 
a refined model but reduce the computational resources of running a 
complex, numerical air quality model such as a photochemical grid model.

In such situations, an attempt should be made to acquire or improve the 
necessary databases and to develop appropriate analytical techniques, 
but the screening technique or reduced-form model may be sufficient in 
conducting regulatory modeling applications when applied in consultation 
with the EPA Regional Office.
    e. Consistent with the general principle described in paragraph 
2.2(a), the EPA may establish a demonstration tool or method as a 
sufficient means for a user or applicant to make a demonstration 
required by regulation, either by itself or as part of a modeling 
demonstration. To be used for such regulatory purposes, such a tool or 
method must be reflected in a codified regulation or have a well-
documented technical basis and reasoning that is contained or 
incorporated in the record of the regulatory decision in which it is 
applied.

                       2.3 Availability of Models

    a. For most of the screening and refined models discussed in the 
Guideline, codes, associated documentation and other useful information 
are publicly available for download from the EPA's Support Center for 
Regulatory Atmospheric Modeling (SCRAM) Web site at https://www.epa.gov/
scram. This is a Web site with which air quality modelers should become 
familiar and regularly visit for important model updates and additional 
clarifications and revisions to modeling guidance documents that are 
applicable to EPA programs and regulations. Codes and documentation may 
also be available from the National Technical Information Service 
(NTIS), http://www.ntis.gov, and, when available, is referenced with the 
appropriate NTIS accession number.

            3.0 Preferred and Alternative Air Quality Models

    a. This section specifies the approach to be taken in determining 
preferred models for use in regulatory air quality programs. The status 
of models developed by the EPA, as well as those submitted to the EPA 
for review and possible inclusion in this Guideline, is discussed in 
this section. The section also provides the criteria and process for 
obtaining EPA approval for use of alternative models for individual 
cases in situations where the preferred models are not applicable or 
available. Additional sources of relevant modeling information are: the 
EPA's Model Clearinghouse \23\ (section 3.3); EPA modeling conferences; 
periodic Regional, State, and Local Modelers' Workshops; and the EPA's 
SCRAM Web site (section 2.3).

[[Page 606]]

    b. When approval is required for a specific modeling technique or 
analytical procedure in this Guideline, we refer to the ``appropriate 
reviewing authority.'' Many states and some local agencies administer 
NSR permitting under programs approved into SIPs. In some EPA regions, 
federal authority to administer NSR permitting and related activities 
has been delegated to state or local agencies. In these cases, such 
agencies ``stand in the shoes'' of the respective EPA Region. Therefore, 
depending on the circumstances, the appropriate reviewing authority may 
be an EPA Regional Office, a state, local, or tribal agency, or perhaps 
the Federal Land Manager (FLM). In some cases, the Guideline requires 
review and approval of the use of an alternative model by the EPA 
Regional Office (sometimes stated as ``Regional Administrator''). For 
all approvals of alternative models or techniques, the EPA Regional 
Office will coordinate and shall seek concurrence with the EPA's Model 
Clearinghouse. If there is any question as to the appropriate reviewing 
authority, you should contact the EPA Regional Office modeling contact 
(https://www3.epa.gov/ttn/scram/guidance_ cont_regions.htm), whose 
jurisdiction generally includes the physical location of the source in 
question and its expected impacts.
    c. In all regulatory analyses, early discussions among the EPA 
Regional Office staff, state, local, and tribal agency staff, industry 
representatives, and where appropriate, the FLM, are invaluable and are 
strongly encouraged. Prior to the actual analyses, agreement on the 
databases to be used, modeling techniques to be applied, and the overall 
technical approach helps avoid misunderstandings concerning the final 
results and may reduce the later need for additional analyses. The 
preparation of a written modeling protocol that is vetted with the 
appropriate reviewing authority helps to keep misunderstandings and 
resource expenditures at a minimum.
    d. The identification of preferred models in this Guideline should 
not be construed as a determination that the preferred models identified 
here are to be permanently used to the exclusion of all others or that 
they are the only models available for relating emissions to air 
quality. The model that most accurately estimates concentrations in the 
area of interest is always sought. However, designation of specific 
preferred models is needed to promote consistency in model selection and 
application.

                          3.1 Preferred Models

                            3.1.1 Discussion

    a. The EPA has developed some models suitable for regulatory 
application, while other models have been submitted by private 
developers for possible inclusion in the Guideline. Refined models that 
are preferred and required by the EPA for particular applications have 
undergone the necessary peer scientific reviews \24 25\ and model 
performance evaluation exercises \26 27\ that include statistical 
measures of model performance in comparison with measured air quality 
data as described in section 2.1.1.
    b. An American Society for Testing and Materials (ASTM) reference 
\28\ provides a general philosophy for developing and implementing 
advanced statistical evaluations of atmospheric dispersion models, and 
provides an example statistical technique to illustrate the application 
of this philosophy. Consistent with this approach, the EPA has 
determined and applied a specific evaluation protocol that provides a 
statistical technique for evaluating model performance for predicting 
peak concentration values, as might be observed at individual monitoring 
locations.\29\
    c. When a single model is found to perform better than others, it is 
recommended for application as a preferred model and listed in appendix 
A. If no one model is found to clearly perform better through the 
evaluation exercise, then the preferred model listed in appendix A may 
be selected on the basis of other factors such as past use, public 
familiarity, resource requirements, and availability. Accordingly, the 
models listed in appendix A meet these conditions:
    i. The model must be written in a common programming language, and 
the executable(s) must run on a common computer platform.
    ii. The model must be documented in a user's guide or model 
formulation report which identifies the mathematics of the model, data 
requirements and program operating characteristics at a level of detail 
comparable to that available for other recommended models in appendix A.
    iii. The model must be accompanied by a complete test dataset 
including input parameters and output results. The test data must be 
packaged with the model in computer-readable form.
    iv. The model must be useful to typical users, e.g., state air 
agencies, for specific air quality control problems. Such users should 
be able to operate the computer program(s) from available documentation.
    v. The model documentation must include a robust comparison with air 
quality data (and/or tracer measurements) or with other well-established 
analytical techniques.
    vi. The developer must be willing to make the model and source code 
available to users at reasonable cost or make them available for public 
access through the Internet or National Technical Information Service. 
The model and its code cannot be proprietary.
    d. The EPA's process of establishing a preferred model includes a 
determination of technical merit, in accordance with the above six 
items, including the practicality of

[[Page 607]]

the model for use in ongoing regulatory programs. Each model will also 
be subjected to a performance evaluation for an appropriate database and 
to a peer scientific review. Models for wide use (not just an isolated 
case) that are found to perform better will be proposed for inclusion as 
preferred models in future Guideline revisions.
    e. No further evaluation of a preferred model is required for a 
particular application if the EPA requirements for regulatory use 
specified for the model in the Guideline are followed. Alternative 
models to those listed in appendix A should generally be compared with 
measured air quality data when they are used for regulatory applications 
consistent with recommendations in section 3.2.

                           3.1.2 Requirements

    a. Appendix A identifies refined models that are preferred for use 
in regulatory applications. If a model is required for a particular 
application, the user must select a model from appendix A or follow 
procedures in section 3.2.2 for use of an alternative model or 
technique. Preferred models may be used without a formal demonstration 
of applicability as long as they are used as indicated in each model 
summary in appendix A. Further recommendations for the application of 
preferred models to specific source applications are found in subsequent 
sections of the Guideline.
    b. If changes are made to a preferred model without affecting the 
modeled concentrations, the preferred status of the model is unchanged. 
Examples of modifications that do not affect concentrations are those 
made to enable use of a different computer platform or those that only 
affect the format or averaging time of the model results. The 
integration of a graphical user interface (GUI) to facilitate setting up 
the model inputs and/or analyzing the model results without otherwise 
altering the preferred model code is another example of a modification 
that does not affect concentrations. However, when any changes are made, 
the Regional Administrator must require a test case example to 
demonstrate that the modeled concentrations are not affected.
    c. A preferred model must be operated with the options listed in 
appendix A for its intended regulatory application. If the regulatory 
options are not applied, the model is no longer ``preferred.'' Any other 
modification to a preferred model that would result in a change in the 
concentration estimates likewise alters its status so that it is no 
longer a preferred model. Use of the modified model must then be 
justified as an alternative model on a case-by-case basis to the 
appropriate reviewing authority and approved by the Regional 
Administrator.
    d. Where the EPA has not identified a preferred model for a 
particular pollutant or situation, the EPA may establish a multi-tiered 
approach for making a demonstration required under PSD or another CAA 
program. The initial tier or tiers may involve use of demonstration 
tools, screening models, screening techniques, or reduced-form models; 
while the last tier may involve the use of demonstration tools, refined 
models or techniques, or alternative models approved under section 3.2.

                         3.2 Alternative Models

                            3.2.1 Discussion

    a. Selection of the best model or techniques for each individual air 
quality analysis is always encouraged, but the selection should be done 
in a consistent manner. A simple listing of models in this Guideline 
cannot alone achieve that consistency nor can it necessarily provide the 
best model for all possible situations. As discussed in section 3.1.1, 
the EPA has determined and applied a specific evaluation protocol that 
provides a statistical technique for evaluating model performance for 
predicting peak concentration values, as might be observed at individual 
monitoring locations.\29\ This protocol is available to assist in 
developing a consistent approach when justifying the use of other-than-
preferred models recommended in the Guideline (i.e., alternative 
models). The procedures in this protocol provide a general framework for 
objective decision-making on the acceptability of an alternative model 
for a given regulatory application. These objective procedures may be 
used for conducting both the technical evaluation of the model and the 
field test or performance evaluation.
    b. This subsection discusses the use of alternate models and defines 
three situations when alternative models may be used. This subsection 
also provides a procedure for implementing 40 CFR 51.166(l)(2) in PSD 
permitting. This provision requires written approval of the 
Administrator for any modification or substitution of an applicable 
model. An applicable model for purposes of 40 CFR 51.166(l) is a 
preferred model in appendix A to the Guideline. Approval to use an 
alternative model under section 3.2 of the Guideline qualifies as 
approval for the modification or substitution of a model under 40 CFR 
51.166(l)(2). The Regional Administrators have delegated authority to 
issue such approvals under section 3.2 of the Guideline, provided that 
such approval is issued after consultation with the EPA's Model 
Clearinghouse and formally documented in a concurrence memorandum from 
the EPA's Model Clearinghouse which demonstrates that the requirements 
within section 3.2 for use of an alternative model have been met.

[[Page 608]]

                           3.2.2 Requirements

    a. Determination of acceptability of an alternative model is an EPA 
Regional Office responsibility in consultation with the EPA's Model 
Clearinghouse as discussed in paragraphs 3.0(b) and 3.2.1(b). Where the 
Regional Administrator finds that an alternative model is more 
appropriate than a preferred model, that model may be used subject to 
the approval of the EPA Regional Office based on the requirements of 
this subsection. This finding will normally result from a determination 
that: (1) A preferred air quality model is not appropriate for the 
particular application; or (2) a more appropriate model or technique is 
available and applicable.
    b. An alternative model shall be evaluated from both a theoretical 
and a performance perspective before it is selected for use. There are 
three separate conditions under which such a model may be approved for 
use:
    1. If a demonstration can be made that the model produces 
concentration estimates equivalent to the estimates obtained using a 
preferred model;
    2. If a statistical performance evaluation has been conducted using 
measured air quality data and the results of that evaluation indicate 
the alternative model performs better for the given application than a 
comparable model in appendix A; or
    3. If there is no preferred model.

Any one of these three separate conditions may justify use of an 
alternative model. Some known alternative models that are applicable for 
selected situations are listed on the EPA's SCRAM Web site (section 
2.3). However, inclusion there does not confer any unique status 
relative to other alternative models that are being or will be developed 
in the future.
    c. Equivalency, condition (1) in paragraph (b) of this subsection, 
is established by demonstrating that the appropriate regulatory 
metric(s) are within  2 percent of the estimates 
obtained from the preferred model. The option to show equivalency is 
intended as a simple demonstration of acceptability for an alternative 
model that is nearly identical (or contains options that can make it 
identical) to a preferred model that it can be treated for practical 
purposes as the preferred model. However, notwithstanding this 
demonstration, models that are not equivalent may be used when one of 
the two other conditions described in paragraphs (d) and (e) of this 
subsection are satisfied.
    d. For condition (2) in paragraph (b) of this subsection, 
established statistical performance evaluation procedures and techniques 
28 29 for determining the acceptability of a model for an 
individual case based on superior performance should be followed, as 
appropriate. Preparation and implementation of an evaluation protocol 
that is acceptable to both control agencies and regulated industry is an 
important element in such an evaluation.
    e. Finally, for condition (3) in paragraph (b) of this subsection, 
an alternative model or technique may be approved for use provided that:
    i. The model or technique has received a scientific peer review;
    ii. The model or technique can be demonstrated to be applicable to 
the problem on a theoretical basis;
    iii. The databases which are necessary to perform the analysis are 
available and adequate;
    iv. Appropriate performance evaluations of the model or technique 
have shown that the model or technique is not inappropriately biased for 
regulatory application \a\; and
---------------------------------------------------------------------------

    \a\ For PSD and other applications that use the model results in an 
absolute sense, the model should not be biased toward underestimates. 
Alternatively, for ozone and PM2.5 SIP attainment 
demonstrations and other applications that use the model results in a 
relative sense, the model should not be biased toward overestimates.
---------------------------------------------------------------------------

    v. A protocol on methods and procedures to be followed has been 
established.
    f. To formally document that the requirements of section 3.2 for use 
of an alternative model are satisfied for a particular application or 
range of applications, a memorandum will be prepared by the EPA's Model 
Clearinghouse through a consultative process with the EPA Regional 
Office.

                      3.3 EPA's Model Clearinghouse

    a. The Regional Administrator has the authority to select models 
that are appropriate for use in a given situation. However, there is a 
need for assistance and guidance in the selection process so that 
fairness, consistency, and transparency in modeling decisions are 
fostered among the EPA Regional Offices and the state, local, and tribal 
agencies. To satisfy that need, the EPA established the Model 
Clearinghouse \23\ to serve a central role of coordination and 
collaboration between EPA headquarters and the EPA Regional Offices. 
Additionally, the EPA holds periodic workshops with EPA Headquarters, 
EPA Regional Offices, and state, local, and tribal agency modeling 
representatives.
    b. The appropriate EPA Regional Office should always be consulted 
for information and guidance concerning modeling methods and 
interpretations of modeling guidance, and to ensure that the air quality 
model user has available the latest most up-to-date policy and 
procedures. As appropriate, the EPA Regional Office may also request 
assistance from the EPA's Model Clearinghouse on other applications of 
models, analytical

[[Page 609]]

techniques, or databases or to clarify interpretation of the Guideline 
or related modeling guidance.
    c. The EPA Regional Office will coordinate with the EPA's Model 
Clearinghouse after an initial evaluation and decision has been 
developed concerning the application of an alternative model. The 
acceptability and formal approval process for an alternative model is 
described in section 3.2.

 4.0 Models for Carbon Monoxide, Lead, Sulfur Dioxide, Nitrogen Dioxide 
                     and Primary Particulate Matter

                             4.1 Discussion

    a. This section identifies modeling approaches generally used in the 
air quality impact analysis of sources that emit the criteria pollutants 
carbon monoxide (CO), lead, sulfur dioxide (SO2), nitrogen 
dioxide (NO2), and primary particulates (PM2.5 and 
PM10).
    b. The guidance in this section is specific to the application of 
the Gaussian plume models identified in appendix A. Gaussian plume 
models assume that emissions and meteorology are in a steady-state, 
which is typically based on an hourly time step. This approach results 
in a plume that has an hourly-averaged distribution of emission mass 
according to a Gaussian curve through the plume. Though Gaussian steady-
state models conserve the mass of the primary pollutant throughout the 
plume, they can still take into account a limited consideration of 
first-order removal processes (e.g., wet and dry deposition) and limited 
chemical conversion (e.g., OH oxidation).
    c. Due to the steady-state assumption, Gaussian plume models are 
generally considered applicable to distances less than 50 km, beyond 
which, modeled predictions of plume impact are likely conservative. The 
locations of these impacts are expected to be unreliable due to changes 
in meteorology that are likely to occur during the travel time.
    d. The applicability of Gaussian plume models may vary depending on 
the topography of the modeling domain, i.e., simple or complex. Simple 
terrain is considered to be an area where terrain features are all lower 
in elevation than the top of the stack(s) of the source(s) in question. 
Complex terrain is defined as terrain exceeding the height of the 
stack(s) being modeled.
    e. Gaussian models determine source impacts at discrete locations 
(receptors) for each meteorological and emission scenario, and generally 
attempt to estimate concentrations at specific sites that represent an 
ensemble average of numerous repetitions of the same ``event.'' 
Uncertainties in model estimates are driven by this formulation, and as 
noted in section 2.1.1, evaluations of model accuracy should focus on 
the reducible uncertainty associated with physics and the formulation of 
the model. The ``irreducible'' uncertainty associated with Gaussian 
plume models may be responsible for variation in concentrations of as 
much as  50 percent.\30\ ``Reducible'' 
uncertainties \16\ can be on a similar scale. For example, Pasquill \31\ 
estimates that, apart from data input errors, maximum ground-level 
concentrations at a given hour for a point source in flat terrain could 
be in error by 50 percent due to these uncertainties. Errors of 5 to 10 
degrees in the measured wind direction can result in concentration 
errors of 20 to 70 percent for a particular time and location, depending 
on stability and station location. Such uncertainties do not indicate 
that an estimated concentration does not occur, only that the precise 
time and locations are in doubt. Composite errors in highest estimated 
concentrations of 10 to 40 percent are found to be typical.\32 33\ 
However, estimates of concentrations paired in time and space with 
observed concentrations are less certain.
    f. Model evaluations and inter-comparisons should take these aspects 
of uncertainty into account. For a regulatory application of a model, 
the emphasis of model evaluations is generally placed on the highest 
modeled impacts. Thus, the Cox-Tikvart model evaluation approach, which 
compares the highest modeled impacts on several timescales, is 
recommended for comparisons of models and measurements and model inter-
comparisons. The approach includes bootstrap techniques to determine the 
significance of various modeled predictions and increases the robustness 
of such comparisons when the number of available measurements are 
limited.\34 35\ Because of the uncertainty in paired modeled and 
observed concentrations, any attempts at calibration of models based on 
these comparisons is of questionable benefit and shall not be done.

                            4.2 Requirements

    a. For NAAQS compliance demonstrations under PSD, use of the 
screening and preferred models for the pollutants listed in this 
subsection shall be limited to the near-field at a nominal distance of 
50 km or less. Near-field application is consistent with capabilities of 
Gaussian plume models and, based on the EPA's assessment, is sufficient 
to address whether a source will cause or contribute to ambient 
concentrations in excess of a NAAQS. In most cases, maximum source 
impacts of inert pollutants will occur within the first 10 to 20 km from 
the source. Therefore, the EPA does not consider a long-range transport 
assessment beyond 50 km necessary for these pollutants if a near-field 
NAAQS compliance demonstration is required.\36\
    b. For assessment of PSD increments within the near-field distance 
of 50 km or less, use of the screening and preferred models for

[[Page 610]]

the pollutants listed in this subsection shall be limited to the same 
screening and preferred models approved for NAAQS compliance 
demonstrations.
    c. To determine if a compliance demonstration for NAAQS and/or PSD 
increments may be necessary beyond 50 km (i.e., long-range transport 
assessment), the following screening approach shall be used to determine 
if a significant ambient impact will occur with particular focus on 
Class I areas and/or the applicable receptors that may be threatened at 
such distances.
    i. Based on application in the near-field of the appropriate 
screening and/or preferred model, determine the significance of the 
ambient impacts at or about 50 km from the new or modifying source. If a 
near-field assessment is not available or this initial analysis 
indicates there may be significant ambient impacts at that distance, 
then further assessment is necessary.
    ii. For assessment of the significance of ambient impacts for NAAQS 
and/or PSD increments, there is not a preferred model or screening 
approach for distances beyond 50 km. Thus, the appropriate reviewing 
authority (paragraph 3.0(b)) and the EPA Regional Office shall be 
consulted in determining the appropriate and agreed upon screening 
technique to conduct the second level assessment. Typically, a 
Lagrangian model is most appropriate to use for these second level 
assessments, but applicants shall reach agreement on the specific model 
and modeling parameters on a case-by-case basis in consultation with the 
appropriate reviewing authority (paragraph 3.0(b)) and EPA Regional 
Office. When Lagrangian models are used in this manner, they shall not 
include plume-depleting processes, such that model estimates are 
considered conservative, as is generally appropriate for screening 
assessments.
    d. In those situations where a cumulative impact analysis for NAAQS 
and/or PSD increments analysis beyond 50 km is necessary, the selection 
and use of an alternative model shall occur in agreement with the 
appropriate reviewing authority (paragraph 3.0(b)) and approval by the 
EPA Regional Office based on the requirements of paragraph 3.2.2(e).

                  4.2.1 Screening Models and Techniques

    a. Where a preliminary or conservative estimate is desired, point 
source screening techniques are an acceptable approach to air quality 
analyses.
    b. As discussed in paragraph 2.2(a), screening models or techniques 
are designed to provide a conservative estimate of concentrations. The 
screening models used in most applications are the screening versions of 
the preferred models for refined applications. The two screening models, 
AERSCREEN 37 38 and CTSCREEN, are screening versions of 
AERMOD (American Meteorological Society (AMS)/EPA Regulatory Model) and 
CTDMPLUS (Complex Terrain Dispersion Model Plus Algorithms for Unstable 
Situations), respectively. AERSCREEN is the recommended screening model 
for most applications in all types of terrain and for applications 
involving building downwash. For those applications in complex terrain 
where the application involves a well-defined hill or ridge, CTSCREEN 
\39\ can be used.
    c. Although AERSCREEN and CTSCREEN are designed to address a single-
source scenario, there are approaches that can be used on a case-by-case 
basis to address multi-source situations using screening meteorology or 
other conservative model assumptions. However, the appropriate reviewing 
authority (paragraph 3.0(b)) shall be consulted, and concurrence 
obtained, on the protocol for modeling multiple sources with AERSCREEN 
or CTSCREEN to ensure that the worst case is identified and assessed.
    d. As discussed in section 4.2.3.4, there are also screening 
techniques built into AERMOD that use simplified or limited chemistry 
assumptions for determining the partitioning of NO and NO2 
for NO2 modeling. These screening techniques are part of the 
EPA's preferred modeling approach for NO2 and do not need to 
be approved as an alternative model. However, as with other screening 
models and techniques, their usage shall occur in agreement with the 
appropriate reviewing authority (paragraph 3.0(b)).
    e. As discussed in section 4.2(c)(ii), there are screening 
techniques needed for long-range transport assessments that will 
typically involve the use of a Lagrangian model. Based on the long-
standing practice and documented capabilities of these models for long-
range transport assessments, the use of a Lagrangian model as a 
screening technique for this purpose does not need to be approved as an 
alternative model. However, their usage shall occur in consultation with 
the appropriate reviewing authority (paragraph 3.0(b)) and EPA Regional 
Office.
    f. All screening models and techniques shall be configured to 
appropriately address the site and problem at hand. Close attention must 
be paid to whether the area should be classified urban or rural in 
accordance with section 7.2.1.1. The climatology of the area must be 
studied to help define the worst-case meteorological conditions. 
Agreement shall be reached between the model user and the appropriate 
reviewing authority (paragraph 3.0(b)) on the choice of the screening 
model or technique for each analysis, on the input data and model 
settings, and the appropriate metric for satisfying regulatory 
requirements.

                            4.2.1.1 AERSCREEN

    a. Released in 2011, AERSCREEN is the EPA's recommended screening 
model for simple and complex terrain for single

[[Page 611]]

sources including point sources, area sources, horizontal stacks, capped 
stacks, and flares. AERSCREEN runs AERMOD in a screening mode and 
consists of two main components: 1) the MAKEMET program which generates 
a site-specific matrix of meteorological conditions for input to the 
AERMOD model; and 2) the AERSCREEN command-prompt interface.
    b. The MAKEMET program generates a matrix of meteorological 
conditions, in the form of AERMOD-ready surface and profile files, based 
on user-specified surface characteristics, ambient temperatures, minimum 
wind speed, and anemometer height. The meteorological matrix is 
generated based on looping through a range of wind speeds, cloud covers, 
ambient temperatures, solar elevation angles, and convective velocity 
scales (w*, for convective conditions only) based on user-specified 
surface characteristics for surface roughness (Zo), Bowen 
ratio (Bo), and albedo (r). For unstable cases, the 
convective mixing height (Zic) is calculated based on w*, and 
the mechanical mixing height (Zim) is calculated for unstable 
and stable conditions based on the friction velocity, u*.
    c. For applications involving simple or complex terrain, AERSCREEN 
interfaces with AERMAP. AERSCREEN also interfaces with BPIPPRM to 
provide the necessary building parameters for applications involving 
building downwash using the Plume Rise Model Enhancements (PRIME) 
downwash algorithm. AERSCREEN generates inputs to AERMOD via MAKEMET, 
AERMAP, and BPIPPRM and invokes AERMOD in a screening mode. The 
screening mode of AERMOD forces the AERMOD model calculations to 
represent values for the plume centerline, regardless of the source-
receptor-wind direction orientation. The maximum concentration output 
from AERSCREEN represents a worst-case 1-hour concentration. Averaging-
time scaling factors of 1.0 for 3-hour, 0.9 for 8-hour, 0.60 for 24-
hour, and 0.10 for annual concentration averages are applied internally 
by AERSCREEN to the highest 1-hour concentration calculated by the model 
for non-area type sources. For area type source concentrations for 
averaging times greater than one hour, the concentrations are equal to 
the 1-hour estimates.\37 40\

                            4.2.1.2 CTSCREEN

    a. CTSCREEN \39 41\ can be used to obtain conservative, yet 
realistic, worst-case estimates for receptors located on terrain above 
stack height. CTSCREEN accounts for the three-dimensional nature of 
plume and terrain interaction and requires detailed terrain data 
representative of the modeling domain. The terrain data must be 
digitized in the same manner as for CTDMPLUS and a terrain processor is 
available.\42\ CTSCREEN is designed to execute a fixed matrix of 
meteorological values for wind speed (u), standard deviation of 
horizontal and vertical wind speeds ([sigma]v, [sigma]w), vertical 
potential temperature gradient (d[thgr]/dz), friction velocity (u*), 
Monin-Obukhov length (L), mixing height (zi) as a function of 
terrain height, and wind directions for both neutral/stable conditions 
and unstable convective conditions. The maximum concentration output 
from CTSCREEN represents a worst-case 1-hour concentration. Time-scaling 
factors of 0.7 for 3-hour, 0.15 for 24-hour and 0.03 for annual 
concentration averages are applied internally by CTSCREEN to the highest 
1-hour concentration calculated by the model.

                  4.2.1.3 Screening in Complex Terrain

    a. For applications utilizing AERSCREEN, AERSCREEN automatically 
generates a polar-grid receptor network with spacing determined by the 
maximum distance to model. If the application warrants a different 
receptor network than that generated by AERSCREEN, it may be necessary 
to run AERMOD in screening mode with a user-defined network. For 
CTSCREEN applications or AERMOD in screening mode outside of AERSCREEN, 
placement of receptors requires very careful attention when modeling in 
complex terrain. Often the highest concentrations are predicted to occur 
under very stable conditions, when the plume is near or impinges on the 
terrain. Under such conditions, the plume may be quite narrow in the 
vertical, so that even relatively small changes in a receptor's location 
may substantially affect the predicted concentration. Receptors within 
about a kilometer of the source may be even more sensitive to location. 
Thus, a dense array of receptors may be required in some cases.
    b. For applications involving AERSCREEN, AERSCREEN interfaces with 
AERMAP to generate the receptor elevations. For applications involving 
CTSCREEN, digitized contour data must be preprocessed \42\ to provide 
hill shape parameters in suitable input format. The user then supplies 
receptor locations either through an interactive program that is part of 
the model or directly, by using a text editor; using both methods to 
select receptor locations will generally be necessary to assure that the 
maximum concentrations are estimated by either model. In cases where a 
terrain feature may ``appear to the plume'' as smaller, multiple hills, 
it may be necessary to model the terrain both as a single feature and as 
multiple hills to determine design concentrations.
    c. Other screening techniques may be acceptable for complex terrain 
cases where established procedures \43\ are used. The user is encouraged 
to confer with the appropriate reviewing authority (paragraph 3.0(b)) if 
any

[[Page 612]]

unforeseen problems are encountered, e.g., applicability, meteorological 
data, receptor siting, or terrain contour processing issues.

                          4.2.2 Refined Models

    a. A brief description of each preferred model for refined 
applications is found in appendix A. Also listed in that appendix are 
availability, the model input requirements, the standard options that 
shall be selected when running the program, and output options.

                             4.2.2.1 AERMOD

    a. For a wide range of regulatory applications in all types of 
terrain, and for aerodynamic building downwash, the required model is 
AERMOD.\44 45\ The AERMOD regulatory modeling system consists of the 
AERMOD dispersion model, the AERMET meteorological processor, and the 
AERMAP terrain processor. AERMOD is a steady-state Gaussian plume model 
applicable to directly emitted air pollutants that employs best state-
of-practice parameterizations for characterizing the meteorological 
influences and dispersion. Differentiation of simple versus complex 
terrain is unnecessary with AERMOD. In complex terrain, AERMOD employs 
the well-known dividing-streamline concept in a simplified simulation of 
the effects of plume-terrain interactions.
    b. The AERMOD modeling system has been extensively evaluated across 
a wide range of scenarios based on numerous field studies, including 
tall stacks in flat and complex terrain settings, sources subject to 
building downwash influences, and low-level non-buoyant sources.\27\ 
These evaluations included several long-term field studies associated 
with operating plants as well as several intensive tracer studies. Based 
on these evaluations, AERMOD has shown consistently good performance, 
with ``errors'' in predicted versus observed peak concentrations, based 
on the Robust Highest Concentration (RHC) metric, consistently within 
the range of 10 to 40 percent (cited in paragraph 4.1(e)).
    c. AERMOD incorporates the PRIME algorithm to account for enhanced 
plume growth and restricted plume rise for plumes affected by building 
wake effects.\46\ The PRIME algorithm accounts for entrainment of plume 
mass into the cavity recirculation region, including re-entrainment of 
plume mass into the wake region beyond the cavity.
    d. AERMOD incorporates the Buoyant Line and Point Source (BLP) 
Dispersion model to account for buoyant plume rise from line sources. 
The BLP option utilizes the standard meteorological inputs provided by 
the AERMET meteorological processor.
    e. The state-of-the-science for modeling atmospheric deposition is 
evolving, new modeling techniques are continually being assessed, and 
their results are being compared with observations. Consequently, while 
deposition treatment is available in AERMOD, the approach taken for any 
purpose shall be coordinated with the appropriate reviewing authority 
(paragraph 3.0(b)).

                            4.2.2.2 CTDMPLUS

    a. If the modeling application involves an elevated point source 
with a well-defined hill or ridge and a detailed dispersion analysis of 
the spatial pattern of plume impacts is of interest, CTDMPLUS is 
available. CTDMPLUS provides greater resolution of concentrations about 
the contour of the hill feature than does AERMOD through a different 
plume-terrain interaction algorithm.

                               4.2.2.3 OCD

    a. If the modeling application involves determining the impact of 
offshore emissions from point, area, or line sources on the air quality 
of coastal regions, the recommended model is the OCD (Offshore and 
Coastal Dispersion) Model. OCD is a straight-line Gaussian model that 
incorporates overwater plume transport and dispersion as well as changes 
that occur as the plume crosses the shoreline. OCD is also applicable 
for situations that involve platform building downwash.

             4.2.3 Pollutant Specific Modeling Requirements

                   4.2.3.1 Models for Carbon Monoxide

    a. Models for assessing the impact of CO emissions are needed to 
meet NSR requirements to address compliance with the CO NAAQS and to 
determine localized impacts from transportations projects. Examples 
include evaluating effects of point sources, congested roadway 
intersections and highways, as well as the cumulative effect of numerous 
sources of CO in an urban area.
    b. The general modeling recommendations and requirements for 
screening models in section 4.2.1 and refined models in section 4.2.2 
shall be applied for CO modeling. Given the relatively low CO background 
concentrations, screening techniques are likely to be adequate in most 
cases. In applying these recommendations and requirements, the existing 
1992 EPA guidance for screening CO impacts from highways may be 
consulted.\47\

                         4.2.3.2 Models for Lead

    a. In January 1999 (40 CFR part 58, appendix D), the EPA gave notice 
that concern about ambient lead impacts was being shifted away from 
roadways and toward a focus on stationary point sources. Thus, models 
for assessing the impact of lead emissions are needed to meet NSR 
requirements to address compliance with the lead NAAQS and for SIP 
attainment demonstrations. The

[[Page 613]]

EPA has also issued guidance on siting ambient monitors in the vicinity 
of stationary point sources.\48\ For lead, the SIP should contain an air 
quality analysis to determine the maximum rolling 3-month average lead 
concentration resulting from major lead point sources, such as smelters, 
gasoline additive plants, etc. The EPA has developed a post-processor to 
calculate rolling 3-month average concentrations from model output.\49\ 
General guidance for lead SIP development is also available.\50\
    b. For major lead point sources, such as smelters, which contribute 
fugitive emissions and for which deposition is important, professional 
judgment should be used, and there shall be coordination with the 
appropriate reviewing authority (paragraph 3.0(b)). For most 
applications, the general requirements for screening and refined models 
of section 4.2.1 and 4.2.2 are applicable to lead modeling.

                    4.2.3.3 Models for Sulfur Dioxide

    a. Models for SO2 are needed to meet NSR requirements to 
address compliance with the SO2 NAAQS and PSD increments, for 
SIP attainment demonstrations,\51\ and for characterizing current air 
quality via modeling.\52\ SO2 is one of a group of highly 
reactive gases known as ``oxides of sulfur'' with largest emissions 
sources being fossil fuel combustion at power plants and other 
industrial facilities.
    b. Given the relatively inert nature of SO2 on the short-
term time scales of interest (i.e., 1-hour) and the sources of 
SO2 (i.e., stationary point sources), the general modeling 
requirements for screening models in section 4.2.1 and refined models in 
section 4.2.2 are applicable for SO2 modeling applications. 
For urban areas, AERMOD automatically invokes a half-life of 4 hours 
\53\ to SO2. Therefore, care must be taken when determining 
whether a source is urban or rural (see section 7.2.1.1 for urban/rural 
determination methodology).

                   4.2.3.4 Models for Nitrogen Dioxide

    a. Models for assessing the impact of sources on ambient 
NO2 concentrations are needed to meet NSR requirements to 
address compliance with the NO2 NAAQS and PSD increments. 
Impact of an individual source on ambient NO2 depends, in 
part, on the chemical environment into which the source's plume is to be 
emitted. This is due to the fact that NO2 sources co-emit NO 
along with NO2 and any emitted NO may react with ambient 
ozone to convert to additional NO2 downwind. Thus, 
comprehensive modeling of NO2 would need to consider the 
ratio of emitted NO and NO2, the ambient levels of ozone and 
subsequent reactions between ozone and NO, and the photolysis of 
NO2 to NO.
    b. Due to the complexity of NO2 modeling, a multi-tiered 
screening approach is required to obtain hourly and annual average 
estimates of NO2.\54\ Since these methods are considered 
screening techniques, their usage shall occur in agreement with the 
appropriate reviewing authority (paragraph 3.0(b)). Additionally, since 
screening techniques are conservative by their nature, there are 
limitations to how these options can be used. Specifically, modeling of 
negative emissions rates should only be done after consultation with the 
EPA Regional Office to ensure that decreases in concentrations would not 
be overestimated. Each tiered approach (see Figure 4-1) accounts for 
increasingly complex considerations of NO2 chemistry and is 
described in paragraphs c through e of this subsection. The tiers of 
NO2 modeling include:
    i. A first-tier (most conservative) ``full'' conversion approach;
    ii. A second-tier approach that assumes ambient equilibrium between 
NO and NO2; and
    iii. A third-tier consisting of several detailed screening 
techniques that account for ambient ozone and the relative amount of NO 
and NO2 emitted from a source.
    c. For Tier 1, use an appropriate refined model (section 4.2.2) to 
estimate nitrogen oxides (NOX) concentrations and assume a 
total conversion of NO to NO2.
    d. For Tier 2, multiply the Tier 1 result(s) by the Ambient Ratio 
Method 2 (ARM2), which provides estimates of representative equilibrium 
ratios of NO2/NOX value based ambient levels of 
NO2 and NOX derived from national data from the 
EPA's Air Quality System (AQS).\55\ The national default for ARM2 
includes a minimum ambient NO2/NOX ratio of 0.5 
and a maximum ambient ratio of 0.9. The reviewing agency may establish 
alternative minimum ambient NO2/NOX values based 
on the source's in-stack emissions ratios, with alternative minimum 
ambient ratios reflecting the source's in-stack NO2/
NOX ratios. Preferably, alternative minimum ambient 
NO2/NOX ratios should be based on source-specific 
data which satisfies all quality assurance procedures that ensure data 
accuracy for both NO2 and NOX within the typical 
range of measured values. However, alternate information may be used to 
justify a source's anticipated NO2/NOX in-stack 
ratios, such as manufacturer test data, state or local agency guidance, 
peer-reviewed literature, and/or the EPA's NO2/NOX 
ratio database.
    e. For Tier 3, a detailed screening technique shall be applied on a 
case-by-case basis. Because of the additional input data requirements 
and complexities associated with the Tier 3 options, their usage shall 
occur in consultation with the EPA Regional Office in addition to the 
appropriate reviewing authority. The Ozone Limiting Method

[[Page 614]]

(OLM) \56\ and the Plume Volume Molar Ratio Method (PVMRM) \57\ are two 
detailed screening techniques that may be used for most sources. These 
two techniques use an appropriate section 4.2.2 model to estimate 
NOX concentrations and then estimate the conversion of 
primary NO emissions to NO2 based on the ambient levels of 
ozone and the plume characteristics. OLM only accounts for 
NO2 formation based on the ambient levels of ozone while 
PVMRM also accommodates distance-dependent conversion ratios based on 
ambient ozone. Both PVMRM and OLM require that ambient ozone 
concentrations be provided on an hourly basis and explicit specification 
of the NO2/NOX in-stack ratios. PVMRM works best 
for relatively isolated and elevated point source modeling while OLM 
works best for large groups of sources, area sources, and near-surface 
releases, including roadway sources.
    f. Alternative models or techniques may be considered on a case-by-
case basis and their usage shall be approved by the EPA Regional Office 
(section 3.2). Such models or techniques should consider individual 
quantities of NO and NO2 emissions, atmospheric transport and 
dispersion, and atmospheric transformation of NO to NO2. 
Dispersion models that account for more explicit photochemistry may also 
be considered as an alternative model to estimate ambient impacts of 
NOX sources.
[GRAPHIC] [TIFF OMITTED] TR17JA17.000

                   4.2.3.5 Models for PM2.5

    a. PM2.5 is a mixture consisting of several diverse 
components.\58\ Ambient PM2.5 generally consists of two 
components: (1) The primary component, emitted directly from a source; 
and (2) the secondary component, formed in the atmosphere from other 
pollutants emitted from the source. Models for PM2.5 are 
needed to meet NSR requirements to address compliance with the 
PM2.5 NAAQS and PSD increments and for SIP attainment 
demonstrations.
    b. For NSR modeling assessments, the general modeling requirements 
for screening models in section 4.2.1 and refined models in section 
4.2.2 are applicable for the primary component of PM2.5, 
while the methods in section 5.4 are applicable for addressing the 
secondary component of PM2.5. Guidance for PSD assessments is 
available for determining the best approach to handling sources of 
primary and secondary PM2.5.\59\
    c. For SIP attainment demonstrations and regional haze reasonable 
progress goal analyses, effects of a control strategy on 
PM2.5 are estimated from the sum of the effects on the 
primary and secondary components composing PM2.5. Model users 
should refer to section 5.4.1 and associated SIP modeling guidance \60\ 
for further details concerning appropriate modeling approaches.
    d. The general modeling requirements for the refined models 
discussed in section 4.2.2 shall be applied for PM2.5 hot-
spot modeling for mobile sources. Specific guidance is available for 
analyzing direct PM2.5 impacts from highways, terminals, and 
other transportation projects.\61\

                   4.2.3.6 Models for PM10

    a. Models for PM10 are needed to meet NSR requirements to 
address compliance with the PM10 NAAQS and PSD increments and 
for SIP attainment demonstrations.

[[Page 615]]

    b. For most sources, the general modeling requirements for screening 
models in section 4.2.1 and refined models in section 4.2.2 shall be 
applied for PM10 modeling. In cases where the particle size 
and its effect on ambient concentrations need to be considered, particle 
deposition may be used on a case-by-case basis and their usage shall be 
coordinated with the appropriate reviewing authority. A SIP development 
guide \62\ is also available to assist in PM10 analyses and 
control strategy development.
    c. Fugitive dust usually refers to dust put into the atmosphere by 
the wind blowing over plowed fields, dirt roads, or desert or sandy 
areas with little or no vegetation. Fugitive emissions include the 
emissions resulting from the industrial process that are not captured 
and vented through a stack, but may be released from various locations 
within the complex. In some unique cases, a model developed specifically 
for the situation may be needed. Due to the difficult nature of 
characterizing and modeling fugitive dust and fugitive emissions, the 
proposed procedure shall be determined in consultation with the 
appropriate reviewing authority (paragraph 3.0(b)) for each specific 
situation before the modeling exercise is begun. Re-entrained dust is 
created by vehicles driving over dirt roads (e.g., haul roads) and dust-
covered roads typically found in arid areas. Such sources can be 
characterized as line, area or volume sources.61 63 Emission 
rates may be based on site-specific data or values from the general 
literature.
    d. Under certain conditions, recommended dispersion models may not 
be suitable to appropriately address the nature of ambient 
PM10. In these circumstances, the alternative modeling 
approach shall be approved by the EPA Regional Office (section 3.2).
    e. The general modeling requirements for the refined models 
discussed in section 4.2.2 shall be applied for PM10 hot-spot 
modeling for mobile sources. Specific guidance is available for 
analyzing direct PM10 impacts from highways, terminals, and 
other transportation projects.\61\

     5.0 Models for Ozone and Secondarily Formed Particulate Matter

                             5.1 Discussion

    a. Air pollutants formed through chemical reactions in the 
atmosphere are referred to as secondary pollutants. For example, ground-
level ozone and a portion of PM2.5 are secondary pollutants 
formed through photochemical reactions. Ozone and secondarily formed 
particulate matter are closely related to each other in that they share 
common sources of emissions and are formed in the atmosphere from 
chemical reactions with similar precursors.
    b. Ozone formation is driven by emissions of NOX and 
volatile organic compounds (VOCs). Ozone formation is a complicated 
nonlinear process that requires favorable meteorological conditions in 
addition to VOC and NOX emissions. Sometimes complex terrain 
features also contribute to the build-up of precursors and subsequent 
ozone formation or destruction.
    c. PM2.5 can be either primary (i.e., emitted directly 
from sources) or secondary in nature. The fraction of PM2.5 
which is primary versus secondary varies by location and season. In the 
United States, PM2.5 is dominated by a variety of chemical 
species or components of atmospheric particles, such as ammonium 
sulfate, ammonium nitrate, organic carbon mass, elemental carbon, and 
other soil compounds and oxidized metals. PM2.5 sulfate, 
nitrate, and ammonium ions are predominantly the result of chemical 
reactions of the oxidized products of SO2 and NOX 
emissions with direct ammonia emissions.\64\
    d. Control measures reducing ozone and PM2.5 precursor 
emissions may not lead to proportional reductions in ozone and 
PM2.5. Modeled strategies designed to reduce ozone or 
PM2.5 levels typically need to consider the chemical coupling 
between these pollutants. This coupling is important in understanding 
processes that control the levels of both pollutants. Thus, when 
feasible, it is important to use models that take into account the 
chemical coupling between ozone and PM2.5. In addition, using 
such a multi-pollutant modeling system can reduce the resource burden 
associated with applying and evaluating separate models for each 
pollutant and promotes consistency among the strategies themselves.
    e. PM2.5 is a mixture consisting of several diverse 
chemical species or components of atmospheric particles. Because 
chemical and physical properties and origins of each component differ, 
it may be appropriate to use either a single model capable of addressing 
several of the important components or to model primary and secondary 
components using different models. Effects of a control strategy on 
PM2.5 is estimated from the sum of the effects on the 
specific components comprising PM2.5.

                           5.2 Recommendations

    a. Chemical transformations can play an important role in defining 
the concentrations and properties of certain air pollutants. Models that 
take into account chemical reactions and physical processes of various 
pollutants (including precursors) are needed for determining the current 
state of air quality, as well as predicting and projecting the future 
evolution of these pollutants. It is important that a modeling system 
provide a realistic representation of chemical and physical processes 
leading to secondary pollutant formation and removal from the 
atmosphere.

[[Page 616]]

    b. Chemical transport models treat atmospheric chemical and physical 
processes such as deposition and motion. There are two types of chemical 
transport models, Eulerian (grid based) and Lagrangian. These types of 
models are differentiated from each other by their frame of reference. 
Eulerian models are based on a fixed frame of reference and Lagrangian 
models use a frame of reference that moves with parcels of air between 
the source and receptor point.\9\ Photochemical grid models are three-
dimensional Eulerian grid-based models that treat chemical and physical 
processes in each grid cell and use diffusion and transport processes to 
move chemical species between grid cells.\9\ These types of models are 
appropriate for assessment of near-field and regional scale reactive 
pollutant impacts from specific sources 7 10 11 12 or all 
sources.13 14 15 In some limited cases, the secondary 
processes can be treated with a box model, ideally in combination with a 
number of other modeling techniques and/or analyses to treat individual 
source sectors.
    c. Regardless of the modeling system used to estimate secondary 
impacts of ozone and/or PM2.5, model results should be 
compared to observation data to generate confidence that the modeling 
system is representative of the local and regional air quality. For 
ozone related projects, model estimates of ozone should be compared with 
observations in both time and space. For PM2.5, model 
estimates of speciated PM2.5 components (such as sulfate ion, 
nitrate ion, etc.) should be compared with observations in both time and 
space.\65\
    d. Model performance metrics comparing observations and predictions 
are often used to summarize model performance. These metrics include 
mean bias, mean error, fractional bias, fractional error, and 
correlation coefficient. \65\ There are no specific levels of any model 
performance metric that indicate ``acceptable'' model performance. The 
EPA's preferred approach for providing context about model performance 
is to compare model performance metrics with similar contemporary 
applications. 60 65 Because model application purpose and 
scope vary, model users should consult with the appropriate reviewing 
authority (paragraph 3.0(b)) to determine what model performance 
elements should be emphasized and presented to provide confidence in the 
regulatory model application.
    e. There is no preferred modeling system or technique for estimating 
ozone or secondary PM2.5 for specific source impacts or to 
assess impacts from multiple sources. For assessing secondary pollutant 
impacts from single sources, the degree of complexity required to assess 
potential impacts varies depending on the nature of the source, its 
emissions, and the background environment. The EPA recommends a two-
tiered approach where the first tier consists of using existing 
technically credible and appropriate relationships between emissions and 
impacts developed from previous modeling that is deemed sufficient for 
evaluating a source's impacts. The second tier consists of more 
sophisticated case-specific modeling analyses. The appropriate tier for 
a given application should be selected in consultation with the 
appropriate reviewing authority (paragraph 3.0(b)) and be consistent 
with EPA guidance.\66\

             5.3 Recommended Models and Approaches for Ozone

    a. Models that estimate ozone concentrations are needed to guide the 
choice of strategies for the purposes of a nonattainment area 
demonstrating future year attainment of the ozone NAAQS. Additionally, 
models that estimate ozone concentrations are needed to assess impacts 
from specific sources or source complexes to satisfy requirements for 
NSR and other regulatory programs. Other purposes for ozone modeling 
include estimating the impacts of specific events on air quality, ozone 
deposition impacts, and planning for areas that may be attaining the 
ozone NAAQS.

 5.3.1 Models for NAAQS Attainment Demonstrations and Multi-Source Air 
                           Quality Assessments

    a. Simulation of ozone formation and transport is a complex 
exercise. Control agencies with jurisdiction over areas with ozone 
problems should use photochemical grid models to evaluate the 
relationship between precursor species and ozone. Use of photochemical 
grid models is the recommended means for identifying control strategies 
needed to address high ozone concentrations in such areas. Judgment on 
the suitability of a model for a given application should consider 
factors that include use of the model in an attainment test, development 
of emissions and meteorological inputs to the model, and choice of 
episodes to model. Guidance on the use of models and other analyses for 
demonstrating attainment of the air quality goals for ozone is 
available. 59 60 Users should consult with the appropriate 
reviewing authority (paragraph 3.0(b)) to ensure the most current 
modeling guidance is applied.

         5.3.2 Models for Single-Source Air Quality Assessments

    a. Depending on the magnitude of emissions, estimating the impact of 
an individual source's emissions of NOX and VOC on ambient 
ozone is necessary for obtaining a permit. The simulation of ozone 
formation and transport requires realistic treatment of atmospheric 
chemistry and deposition. Models (e.g., Lagrangian and photochemical 
grid

[[Page 617]]

models) that integrate chemical and physical processes important in the 
formation, decay, and transport of ozone and important precursor species 
should be applied. Photochemical grid models are primarily designed to 
characterize precursor emissions and impacts from a wide variety of 
sources over a large geographic area but can also be used to assess the 
impacts from specific sources. \7 11 12\
    b. The first tier of assessment for ozone impacts involves those 
situations where existing technical information is available (e.g., 
results from existing photochemical grid modeling, published empirical 
estimates of source specific impacts, or reduced-form models) in 
combination with other supportive information and analysis for the 
purposes of estimating secondary impacts from a particular source. The 
existing technical information should provide a credible and 
representative estimate of the secondary impacts from the project 
source. The appropriate reviewing authority (paragraph 3.0(b)) and 
appropriate EPA guidance \66\ should be consulted to determine what 
types of assessments may be appropriate on a case-by-case basis.
    c. The second tier of assessment for ozone impacts involves those 
situations where existing technical information is not available or a 
first tier demonstration indicates a more refined assessment is needed. 
For these situations, chemical transport models should be used to 
address single-source impacts. Special considerations are needed when 
using these models to evaluate the ozone impact from an individual 
source. Guidance on the use of models and other analyses for 
demonstrating the impacts of single sources for ozone is available. \66\ 
This guidance document provides a more detailed discussion of the 
appropriate approaches to obtaining estimates of ozone impacts from a 
single source. Model users should use the latest version of the guidance 
in consultation with the appropriate reviewing authority (paragraph 
3.0(b)) to determine the most suitable refined approach for single-
source ozone modeling on a case-by-case basis.

      5.4 Recommended Models and Approaches for Secondarily Formed 
                            PM2.5

    a. Models that estimate PM2.5 concentrations are needed 
to guide the choice of strategies for the purposes of a nonattainment 
area demonstrating future year attainment of the PM2.5 NAAQS. 
Additionally, models that estimate PM2.5 concentrations are 
needed to assess impacts from specific sources or source complexes to 
satisfy requirements for NSR and other regulatory programs. Other 
purposes for PM2.5 modeling include estimating the impacts of 
specific events on air quality, visibility, deposition impacts, and 
planning for areas that may be attaining the PM2.5 NAAQS.

 5.4.1 Models for NAAQS Attainment Demonstrations and Multi-Source Air 
                           Quality Assessments

    a. Models for PM2.5 are needed to assess the adequacy of 
a proposed strategy for meeting the annual and 24-hour PM2.5 
NAAQS. Modeling primary and secondary PM2.5 can be a multi-
faceted and complex problem, especially for secondary components of 
PM2.5 such as sulfates and nitrates. Control agencies with 
jurisdiction over areas with secondary PM2.5 problems should 
use models that integrate chemical and physical processes important in 
the formation, decay, and transport of these species (e.g., 
photochemical grid models). Suitability of a modeling approach or mix of 
modeling approaches for a given application requires technical judgment 
as well as professional experience in choice of models, use of the 
model(s) in an attainment test, development of emissions and 
meteorological inputs to the model, and selection of days to model. 
Guidance on the use of models and other analyses for demonstrating 
attainment of the air quality goals for PM2.5 is 
available.59 60 Users should consult with the appropriate 
reviewing authority (paragraph 3.0(b)) to ensure the most current 
modeling guidance is applied.

         5.4.2 Models for Single-Source Air Quality Assessments

    a. Depending on the magnitude of emissions, estimating the impact of 
an individual source's emissions on secondary particulate matter 
concentrations may be necessary for obtaining a permit. Primary 
PM2.5 components shall be simulated using the general 
modeling requirements in section 4.2.3.5. The simulation of secondary 
particulate matter formation and transport is a complex exercise 
requiring realistic treatment of atmospheric chemistry and deposition. 
Models should be applied that integrate chemical and physical processes 
important in the formation, decay, and transport of these species (e.g., 
Lagrangian and photochemical grid models). Photochemical grid models are 
primarily designed to characterize precursor emissions and impacts from 
a wide variety of sources over a large geographic area and can also be 
used to assess the impacts from specific sources.7 10 For 
situations where a project source emits both primary PM2.5 
and PM2.5 precursors, the contribution from both should be 
combined for use in determining the source's ambient impact. Approaches 
for combining primary and secondary impacts are provided in appropriate 
guidance for single source permit related demonstrations. \66\

[[Page 618]]

    b. The first tier of assessment for secondary PM2.5 
impacts involves those situations where existing technical information 
is available (e.g., results from existing photochemical grid modeling, 
published empirical estimates of source specific impacts, or reduced-
form models) in combination with other supportive information and 
analysis for the purposes of estimating secondary impacts from a 
particular source. The existing technical information should provide a 
credible and representative estimate of the secondary impacts from the 
project source. The appropriate reviewing authority (paragraph 3.0(b)) 
and appropriate EPA guidance \66\ should be consulted to determine what 
types of assessments may be appropriate on a case-by-case basis.
    c. The second tier of assessment for secondary PM2.5 
impacts involves those situations where existing technical information 
is not available or a first tier demonstration indicates a more refined 
assessment is needed. For these situations, chemical transport models 
should be used for assessments of single-source impacts. Special 
considerations are needed when using these models to evaluate the 
secondary particulate matter impact from an individual source. Guidance 
on the use of models and other analyses for demonstrating the impacts of 
single sources for secondary PM2.5 is available. \66\ This 
guidance document provides a more detailed discussion of the appropriate 
approaches to obtaining estimates of secondary particulate matter 
concentrations from a single source. Model users should use the latest 
version of this guidance in consultation with the appropriate reviewing 
authority (paragraph 3.0(b)) to determine the most suitable single-
source modeling approach for secondary PM2.5 on a case-by-
case basis.

   6.0 Modeling for Air Quality Related Values and Other Governmental 
                                Programs

                             6.1 Discussion

    a. Other federal government agencies and state, local, and tribal 
agencies with air quality and land management responsibilities have also 
developed specific modeling approaches for their own regulatory or other 
requirements. Although such regulatory requirements and guidance have 
come about because of EPA rules or standards, the implementation of such 
regulations and the use of the modeling techniques is under the 
jurisdiction of the agency issuing the guidance or directive. This 
section covers such situations with reference to those guidance 
documents, when they are available.
    b. When using the model recommended or discussed in the Guideline in 
support of programmatic requirements not specifically covered by EPA 
regulations, the model user should consult the appropriate federal, 
state, local, or tribal agency to ensure the proper application and use 
of the models and/or techniques. These agencies have developed specific 
modeling approaches for their own regulatory or other requirements. Most 
of the programs have, or will have when fully developed, separate 
guidance documents that cover the program and a discussion of the tools 
that are needed. The following paragraphs reference those guidance 
documents, when they are available.

                     6.2 Air Quality Related Values

    a. The 1990 CAA Amendments give FLMs an ``affirmative 
responsibility'' to protect the natural and cultural resources of Class 
I areas from the adverse impacts of air pollution and to provide the 
appropriate procedures and analysis techniques. The CAA identifies the 
FLM as the Secretary of the department, or their designee, with 
authority over these lands. Mandatory Federal Class I areas are defined 
in the CAA as international parks, national parks over 6,000 acres, and 
wilderness areas and memorial parks over 5,000 acres, established as of 
1977. The FLMs are also concerned with the protection of resources in 
federally managed Class II areas because of other statutory mandates to 
protect these areas. Where state or tribal agencies have successfully 
petitioned the EPA and lands have been redesignated to Class I status, 
these agencies may have equivalent responsibilities to that of the FLMs 
for these non-federal Class I areas as described throughout the 
remainder of section 6.2.
    b. The FLM agency responsibilities include the review of air quality 
permit applications from proposed new or modified major pollution 
sources that may affect these Class I areas to determine if emissions 
from a proposed or modified source will cause or contribute to adverse 
impacts on air quality related values (AQRVs) of a Class I area and 
making recommendations to the FLM. AQRVs are resources, identified by 
the FLM agencies, that have the potential to be affected by air 
pollution. These resources may include visibility, scenic, cultural, 
physical, or ecological resources for a particular area. The FLM 
agencies take into account the particular resources and AQRVs that would 
be affected; the frequency and magnitude of any potential impacts; and 
the direct, indirect, and cumulative effects of any potential impacts in 
making their recommendations.
    c. While the AQRV notification and impact analysis requirements are 
outlined in the PSD regulations at 40 CFR 51.166(p) and 40 CFR 52.21(p), 
determination of appropriate analytical methods and metrics for AQRV's 
are determined by the FLM agencies and are published in guidance 
external to the general recommendations of this paragraph.
    d. To develop greater consistency in the application of air quality 
models to assess

[[Page 619]]

potential AQRV impacts in both Class I areas and protected Class II 
areas, the FLM agencies have developed the Federal Land Managers' Air 
Quality Related Values Work Group Phase I Report (FLAG).\67\ FLAG 
focuses upon specific technical and policy issues associated with 
visibility impairment, effects of pollutant deposition on soils and 
surface waters, and ozone effects on vegetation. Model users should 
consult the latest version of the FLAG report for current modeling 
guidance and with affected FLM agency representatives for any 
application specific guidance which is beyond the scope of the 
Guideline.

                            6.2.1 Visibility

    a. Visibility in important natural areas (e.g., Federal Class I 
areas) is protected under a number of provisions of the CAA, including 
sections 169A and 169B (addressing impacts primarily from existing 
sources) and section 165 (new source review). Visibility impairment is 
caused by light scattering and light absorption associated with 
particles and gases in the atmosphere. In most areas of the country, 
light scattering by PM2.5 is the most significant component 
of visibility impairment. The key components of PM2.5 
contributing to visibility impairment include sulfates, nitrates, 
organic carbon, elemental carbon, and crustal material.\67\
    b. Visibility regulations (40 CFR 51.300 through 51.309) require 
state, local, and tribal agencies to mitigate current and prevent future 
visibility impairment in any of the 156 mandatory Federal Class I areas 
where visibility is considered an important attribute. In 1999, the EPA 
issued revisions to the regulations to address visibility impairment in 
the form of regional haze, which is caused by numerous, diverse sources 
(e.g., stationary, mobile, and area sources) located across a broad 
region (40 CFR 51.308 through 51.309). The state of relevant scientific 
knowledge has expanded significantly since that time. A number of 
studies and reports 68 69 have concluded that long-range 
transport (e.g., up to hundreds of kilometers) of fine particulate 
matter plays a significant role in visibility impairment across the 
country. Section 169A of the CAA requires states to develop SIPs 
containing long-term strategies for remedying existing and preventing 
future visibility impairment in the 156 mandatory Class I Federal areas, 
where visibility is considered an important attribute. In order to 
develop long-term strategies to address regional haze, many state, 
local, and tribal agencies will need to conduct regional-scale modeling 
of fine particulate concentrations and associated visibility impairment.
    c. The FLAG visibility modeling recommendations are divided into two 
distinct sections to address different requirements for: (1) Near field 
modeling where plumes or layers are compared against a viewing 
background, and (2) distant/multi-source modeling for plumes and 
aggregations of plumes that affect the general appearance of a 
scene.\67\ The recommendations separately address visibility assessments 
for sources proposing to locate relatively near and at farther distances 
from these areas.\67\

     6.2.1.1 Models for Estimating Near-Field Visibility Impairment

    a. To calculate the potential impact of a plume of specified 
emissions for specific transport and dispersion conditions (``plume 
blight'') for source-receptor distances less than 50 km, a screening 
model and guidance are available.67 70 If a more 
comprehensive analysis is necessary, a refined model should be selected. 
The model selection, procedures, and analyses should be determined in 
consultation with the appropriate reviewing authority (paragraph 3.0(b)) 
and the affected FLM(s).

   6.2.1.2 Models for Estimating Visibility Impairment for Long-Range 
                                Transport

    a. Chemical transformations can play an important role in defining 
the concentrations and properties of certain air pollutants. Models that 
take into account chemical reactions and physical processes of various 
pollutants (including precursors) are needed for determining the current 
state of air quality, as well as predicting and projecting the future 
evolution of these pollutants. It is important that a modeling system 
provide a realistic representation of chemical and physical processes 
leading to secondary pollutant formation and removal from the 
atmosphere.
    b. Chemical transport models treat atmospheric chemical and physical 
processes such as deposition and motion. There are two types of chemical 
transport models, Eulerian (grid based) and Lagrangian. These types of 
models are differentiated from each other by their frame of reference. 
Eulerian models are based on a fixed frame of reference and Lagrangian 
models use a frame of reference that moves with parcels of air between 
the source and receptor point.\9\ Photochemical grid models are three-
dimensional Eulerian grid-based models that treat chemical and physical 
processes in each grid cell and use diffusion and transport processes to 
move chemical species between grid cells.\9\ These types of models are 
appropriate for assessment of near-field and regional scale reactive 
pollutant impacts from specific sources 7 10 11 12 or all 
sources.13 14 15
    c. Development of the requisite meteorological and emissions 
databases necessary for use of photochemical grid models to estimate 
AQRVs should conform to recommendations in section 8 and those outlined 
in the EPA's Modeling Guidance for

[[Page 620]]

Demonstrating Attainment of Air Quality Goals for Ozone, 
PM2.5, and Regional Haze.\60\ Demonstration of the adequacy 
of prognostic meteorological fields can be established through 
appropriate diagnostic and statistical performance evaluations 
consistent with recommendations provided in the appropriate 
guidance.\60\ Model users should consult the latest version of this 
guidance and with the appropriate reviewing authority (paragraph 3.0(b)) 
for any application-specific guidance that is beyond the scope of this 
subsection.

             6.2.2 Models for Estimating Deposition Impacts

    a. For many Class I areas, AQRVs have been identified that are 
sensitive to atmospheric deposition of air pollutants. Emissions of 
NOX, sulfur oxides, NH3, mercury, and secondary 
pollutants such as ozone and particulate matter affect components of 
ecosystems. In sensitive ecosystems, these compounds can acidify soils 
and surface waters, add nutrients that change biodiversity, and affect 
the ecosystem services provided by forests and natural areas.\67\ To 
address the relationship between deposition and ecosystem effects, the 
FLM agencies have developed estimates of critical loads. A critical load 
is defined as, ``A quantitative estimate of an exposure to one or more 
pollutants below which significant harmful effects on specified 
sensitive elements of the environment do not occur according to present 
knowledge.'' \71\
    b. The FLM deposition modeling recommendations are divided into two 
distinct sections to address different requirements for: (1) Near field 
modeling, and (2) distant/multi-source modeling for cumulative effects. 
The recommendations separately address deposition assessments for 
sources proposing to locate relatively near and at farther distances 
from these areas.\67\ Where the source and receptors are not in close 
proximity, chemical transport (e.g., photochemical grid) models 
generally should be applied for an assessment of deposition impacts due 
to one or a small group of sources. Over these distances, chemical and 
physical transformations can change atmospheric residence time due to 
different propensity for deposition to the surface of different forms of 
nitrate and sulfate. Users should consult the latest version of the FLAG 
report \67\ and relevant FLM representatives for guidance on the use of 
models for deposition. Where source and receptors are in close 
proximity, users should contact the appropriate FLM for application-
specific guidance.

          6.3 Modeling Guidance for Other Governmental Programs

    a. Dispersion and photochemical grid modeling may need to be 
conducted to ensure that individual and cumulative offshore oil and gas 
exploration, development, and production plans and activities do not 
significantly affect the air quality of any state as required under the 
Outer Continental Shelf Lands Act (OCSLA). Air quality modeling requires 
various input datasets, including emissions sources, meteorology, and 
pre-existing pollutant concentrations. For sources under the reviewing 
authority of the Department of Interior, Bureau of Ocean Energy 
Management (BOEM), guidance for the development of all necessary Outer 
Continental Shelf (OCS) air quality modeling inputs and appropriate 
model selection and application is available from the BOEM's Web site: 
https://www.boem.gov/GOMR-Environmental-Compliance.
    b. The Federal Aviation Administration (FAA) is the appropriate 
reviewing authority for air quality assessments of primary pollutant 
impacts at airports and air bases. The Aviation Environmental Design 
Tool (AEDT) is developed and supported by the FAA, and is appropriate 
for air quality assessment of primary pollutant impacts at airports or 
air bases. AEDT has adopted AERMOD for treating dispersion. Application 
of AEDT is intended for estimating the change in emissions for aircraft 
operations, point source, and mobile source emissions on airport 
property and quantify the associated pollutant level- concentrations. 
AEDT is not intended for PSD, SIP, or other regulatory air quality 
analyses of point or mobile sources at or peripheral to airport property 
that are unrelated to airport operations. The latest version of AEDT may 
be obtained from the FAA at: https://aedt.faa.gov.

                   7.0 General Modeling Considerations

                             7.1 Discussion

    a. This section contains recommendations concerning a number of 
different issues not explicitly covered in other sections of the 
Guideline. The topics covered here are not specific to any one program 
or modeling area, but are common to dispersion modeling analyses for 
criteria pollutants.

                           7.2 Recommendations

                            7.2.1 All Sources

                     7.2.1.1 Dispersion Coefficients

    a. For any dispersion modeling exercise, the urban or rural 
determination of a source is critical in determining the boundary layer 
characteristics that affect the model's prediction of downwind 
concentrations. Historically, steady-state Gaussian plume models used in 
most applications have employed dispersion coefficients based on 
Pasquill-Gifford \72\ in rural areas and McElroy-Pooler \73\ in urban 
areas. These coefficients are still incorporated in the BLP and OCD 
models.

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However, the AERMOD model incorporates a more up-to-date 
characterization of the atmospheric boundary layer using continuous 
functions of parameterized horizontal and vertical turbulence based on 
Monin-Obukhov similarity (scaling) relationships.\44\ Another key 
feature of AERMOD's formulation is the option to use directly observed 
variables of the boundary layer to parameterize 
dispersion.44 45
    b. The selection of rural or urban dispersion coefficients in a 
specific application should follow one of the procedures suggested by 
Irwin \74\ to determine whether the character of an area is primarily 
urban or rural (of the two methods, the land use procedure is considered 
more definitive.):
    i. Land Use Procedure: (1) Classify the land use within the total 
area, Ao, circumscribed by a 3 km radius circle about the 
source using the meteorological land use typing scheme proposed by Auer; 
\75\ (2) if land use types I1, I2, C1, R2, and R3 account for 50 percent 
or more of Ao, use urban dispersion coefficients; otherwise, 
use appropriate rural dispersion coefficients.
    ii. Population Density Procedure: (1) Compute the average population 
density, p per square kilometer with Ao as defined above; (2) 
If p is greater than 750 people per square kilometer, use urban 
dispersion coefficients; otherwise use appropriate rural dispersion 
coefficients.
    c. Population density should be used with caution and generally not 
be applied to highly industrialized areas where the population density 
may be low and, thus, a rural classification would be indicated. 
However, the area is likely to be sufficiently built-up so that the 
urban land use criteria would be satisfied. Therefore, in this case, the 
classification should be ``urban'' and urban dispersion parameters 
should be used.
    d. For applications of AERMOD in urban areas, under either the Land 
Use Procedure or the Population Density Procedure, the user needs to 
estimate the population of the urban area affecting the modeling domain 
because the urban influence in AERMOD is scaled based on a user-
specified population. For non-population oriented urban areas, or areas 
influenced by both population and industrial activity, the user will 
need to estimate an equivalent population to adequately account for the 
combined effects of industrialized areas and populated areas within the 
modeling domain. Selection of the appropriate population for these 
applications should be determined in consultation with the appropriate 
reviewing authority (paragraph 3.0(b)) and the latest version of the 
AERMOD Implementation Guide.\76\
    e. It should be noted that AERMOD allows for modeling rural and 
urban sources in a single model run. For analyses of whole urban 
complexes, the entire area should be modeled as an urban region if most 
of the sources are located in areas classified as urban. For tall stacks 
located within or adjacent to small or moderate sized urban areas, the 
stack height or effective plume height may extend above the urban 
boundary layer and, therefore, may be more appropriately modeled using 
rural coefficients. Model users should consult with the appropriate 
reviewing authority (paragraph 3.0(b)) and the latest version of the 
AERMOD Implementation Guide \76\ when evaluating this situation.
    f. Buoyancy-induced dispersion (BID), as identified by Pasquill,\77\ 
is included in the preferred models and should be used where buoyant 
sources (e.g., those involving fuel combustion) are involved.

                          7.2.1.2 Complex Winds

    a. Inhomogeneous local winds. In many parts of the United States, 
the ground is neither flat nor is the ground cover (or land use) 
uniform. These geographical variations can generate local winds and 
circulations, and modify the prevailing ambient winds and circulations. 
Typically, geographic effects are more apparent when the ambient winds 
are light or calm, as stronger synoptic or mesoscale winds can modify, 
or even eliminate the weak geographic circulations.\78\ In general, 
these geographically induced wind circulation effects are named after 
the source location of the winds, e.g., lake and sea breezes, and 
mountain and valley winds. In very rugged hilly or mountainous terrain, 
along coastlines, or near large land use variations, the characteristics 
of the winds are a balance of various forces, such that the assumptions 
of steady-state straight-line transport both in time and space are 
inappropriate. In such cases, a model should be chosen to fully treat 
the time and space variations of meteorology effects on transport and 
dispersion. The setup and application of such a model should be 
determined in consultation with the appropriate reviewing authority 
(paragraph 3.0(b)) consistent with limitations of paragraph 3.2.2(e). 
The meteorological input data requirements for developing the time and 
space varying three-dimensional winds and dispersion meteorology for 
these situations are discussed in paragraph 8.4.1.2(c). Examples of 
inhomogeneous winds include, but are not limited to, situations 
described in the following paragraphs:
    i. Inversion breakup fumigation. Inversion breakup fumigation occurs 
when a plume (or multiple plumes) is emitted into a stable layer of air 
and that layer is subsequently mixed to the ground through convective 
transfer of heat from the surface or because of advection to less stable 
surroundings. Fumigation may cause excessively high concentrations, but 
is usually rather short-lived at a given receptor. There are no 
recommended refined techniques to model this phenomenon. There are, 
however, screening

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procedures \40\ that may be used to approximate the concentrations. 
Considerable care should be exercised in using the results obtained from 
the screening techniques.
    ii. Shoreline fumigation. Fumigation can be an important phenomenon 
on and near the shoreline of bodies of water. This can affect both 
individual plumes and area-wide emissions. When fumigation conditions 
are expected to occur from a source or sources with tall stacks located 
on or just inland of a shoreline, this should be addressed in the air 
quality modeling analysis. The EPA has evaluated several coastal 
fumigation models, and the evaluation results of these models are 
available for their possible application on a case-by-case basis when 
air quality estimates under shoreline fumigation conditions are 
needed.\79\ Selection of the appropriate model for applications where 
shoreline fumigation is of concern should be determined in consultation 
with the appropriate reviewing authority (paragraph 3.0(b)).
    iii. Stagnation. Stagnation conditions are characterized by calm or 
very low wind speeds, and variable wind directions. These stagnant 
meteorological conditions may persist for several hours to several days. 
During stagnation conditions, the dispersion of air pollutants, 
especially those from low-level emissions sources, tends to be 
minimized, potentially leading to relatively high ground-level 
concentrations. If point sources are of interest, users should note the 
guidance provided in paragraph (a) of this subsection. Selection of the 
appropriate model for applications where stagnation is of concern should 
be determined in consultation with the appropriate reviewing authority 
(paragraph 3.0(b)).

              7.2.1.3 Gravitational Settling and Deposition

    a. Gravitational settling and deposition may be directly included in 
a model if either is a significant factor. When particulate matter 
sources can be quantified and settling and dry deposition are problems, 
use professional judgment along with coordination with the appropriate 
reviewing authority (paragraph 3.0(b)). AERMOD contains algorithms for 
dry and wet deposition of gases and particles.\80\ For other Gaussian 
plume models, an ``infinite half-life'' may be used for estimates of 
particle concentrations when only exponential decay terms are used for 
treating settling and deposition. Lagrangian models have varying degrees 
of complexity for dealing with settling and deposition and the selection 
of a parameterization for such should be included in the approval 
process for selecting a Lagrangian model. Eulerian grid models tend to 
have explicit parameterizations for gravitational settling and 
deposition as well as wet deposition parameters already included as part 
of the chemistry scheme.

                        7.2.2 Stationary Sources

             7.2.2.1 Good Engineering Practice Stack Height

    a. The use of stack height credit in excess of Good Engineering 
Practice (GEP) stack height or credit resulting from any other 
dispersion technique is prohibited in the development of emissions 
limits by 40 CFR 51.118 and 40 CFR 51.164. The definition of GEP stack 
height and dispersion technique are contained in 40 CFR 51.100. Methods 
and procedures for making the appropriate stack height calculations, 
determining stack height credits and an example of applying those 
techniques are found in several references,81 82 83 84 that 
provide a great deal of additional information for evaluating and 
describing building cavity and wake effects.
    b. If stacks for new or existing major sources are found to be less 
than the height defined by the EPA's refined formula for determining GEP 
height, then air quality impacts associated with cavity or wake effects 
due to the nearby building structures should be determined. The EPA 
refined formula height is defined as H + 1.5L.\83\ Since the definition 
of GEP stack height defines excessive concentrations as a maximum 
ground-level concentration due in whole or in part to downwash of at 
least 40 percent in excess of the maximum concentration without 
downwash, the potential air quality impacts associated with cavity and 
wake effects should also be considered for stacks that equal or exceed 
the EPA formula height for GEP. The AERSCREEN model can be used to 
obtain screening estimates of potential downwash influences, based on 
the PRIME downwash algorithm incorporated in the AERMOD model. If more 
refined concentration estimates are required, AERMOD should be used 
(section 4.2.2).

                           7.2.2.2 Plume Rise

    a. The plume rise methods of Briggs 85 86 are 
incorporated in many of the preferred models and are recommended for use 
in many modeling applications. In AERMOD,44 45 for the stable 
boundary layer, plume rise is estimated using an iterative approach, 
similar to that in the CTDMPLUS model. In the convective boundary layer, 
plume rise is superposed on the displacements by random convective 
velocities.\87\ In AERMOD, plume rise is computed using the methods of 
Briggs, except in cases involving building downwash, in which a 
numerical solution of the mass, energy, and momentum conservation laws 
is performed.\88\ No explicit provisions in these models are made for 
multistack plume rise enhancement or the handling of such special plumes 
as flares.

[[Page 623]]

    b. Gradual plume rise is generally recommended where its use is 
appropriate: (1) In AERMOD; (2) in complex terrain screening procedures 
to determine close-in impacts; and (3) when calculating the effects of 
building wakes. The building wake algorithm in AERMOD incorporates and 
exercises the thermodynamically based gradual plume rise calculations as 
described in paragraph (a) of this subsection. If the building wake is 
calculated to affect the plume for any hour, gradual plume rise is also 
used in downwind dispersion calculations to the distance of final plume 
rise, after which final plume rise is used. Plumes captured by the near 
wake are re-emitted to the far wake as a ground-level volume source.
    c. Stack tip downwash generally occurs with poorly constructed 
stacks and when the ratio of the stack exit velocity to wind speed is 
small. An algorithm developed by Briggs \86\ is the recommended 
technique for this situation and is used in preferred models for point 
sources.
    d. On a case-by-case basis, refinements to the preferred model may 
be considered for plume rise and downwash effects and shall occur in 
agreement with the appropriate reviewing authority (paragraph 3.0(b)) 
and approval by the EPA Regional Office based on the requirements of 
section 3.2.2.

                          7.2.3 Mobile Sources

    a. Emissions of primary pollutants from mobile sources can be 
modeled with an appropriate model identified in section 4.2. Screening 
of mobile sources can be accomplished by using screening meteorology, 
e.g., worst-case meteorological conditions. Maximum hourly 
concentrations computed from screening modeling can be converted to 
longer averaging periods using the scaling ratios specified in the 
AERSCREEN User's Guide.\37\
    b. Mobile sources can be modeled in AERMOD as either line (i.e., 
elongated area) sources or as a series of volume sources. However, since 
mobile source modeling usually includes an analysis of very near-source 
impacts (e.g., hot-spot modeling, which can include receptors within 5-
10 meters (m) of the roadway), the results can be highly sensitive to 
the characterization of the mobile emissions. Important characteristics 
for both line/area and volume sources include the plume release height, 
source width, and initial dispersion characteristics, and should also 
take into account the impact of traffic-induced turbulence that can 
cause roadway sources to have larger initial dimensions than might 
normally be used for representing line sources.
    c. The EPA's quantitative PM hot-spot guidance \61\ and Haul Road 
Workgroup Final Report\63\ provide guidance on the appropriate 
characterization of mobile sources as a function of the roadway and 
vehicle characteristics. The EPA's quantitative PM hot-spot guidance 
includes important considerations and should be consulted when modeling 
roadway links. Area, line or volume sources may be used for modeling 
mobile sources. However, experience in the field has shown that area 
sources may be easier to characterize correctly compared to volume 
sources. If volume sources are used, it is particularly important to 
ensure that roadway emissions are appropriately spaced when using volume 
source so that the emissions field is uniform across the roadway. 
Additionally, receptor placement is particularly important for volume 
sources that have ``exclusion zones'' where concentrations are not 
calculated for receptors located ``within'' the volume sources, i.e., 
less than 2.15 times the initial lateral dispersion coefficient from the 
center of the volume.\61\ Placing receptors in these ``exclusion zones'' 
will result in underestimates of roadway impacts.

                          8.0 Model Input Data

    a. Databases and related procedures for estimating input parameters 
are an integral part of the modeling process. The most appropriate input 
data available should always be selected for use in modeling analyses. 
Modeled concentrations can vary widely depending on the source data or 
meteorological data used. This section attempts to minimize the 
uncertainty associated with database selection and use by identifying 
requirements for input data used in modeling. More specific data 
requirements and the format required for the individual models are 
described in detail in the user's guide and/or associated documentation 
for each model.

                           8.1 Modeling Domain

                            8.1.1 Discussion

    a. The modeling domain is the geographic area for which the required 
air quality analyses for the NAAQS and PSD increments are conducted.

                           8.1.2 Requirements

    a. For a NAAQS or PSD increments assessment, the modeling domain or 
project's impact area shall include all locations where the emissions of 
a pollutant from the new or modifying source(s) may cause a significant 
ambient impact. This impact area is defined as an area with a radius 
extending from the new or modifying source to: (1) The most distant 
location where air quality modeling predicts a significant ambient 
impact will occur, or (2) the nominal 50 km distance considered 
applicable for Gaussian dispersion models, whichever is less. The 
required air quality analysis shall be carried out within this 
geographical area with characterization of source impacts, nearby source 
impacts,

[[Page 624]]

and background concentrations, as recommended later in this section.
    b. For SIP attainment demonstrations for ozone and PM2.5, 
or regional haze reasonable progress goal analyses, the modeling domain 
is determined by the nature of the problem being modeled and the spatial 
scale of the emissions that impact the nonattainment or Class I area(s). 
The modeling domain shall be designed so that all major upwind source 
areas that influence the downwind nonattainment area are included in 
addition to all monitor locations that are currently or recently 
violating the NAAQS or close to violating the NAAQS in the nonattainment 
area. Similarly, all Class I areas to be evaluated in a regional haze 
modeling application shall be included and sufficiently distant from the 
edge of the modeling domain. Guidance on the determination of the 
appropriate modeling domain for photochemical grid models in 
demonstrating attainment of these air quality goals is available.\60\ 
Users should consult the latest version of this guidance for the most 
current modeling guidance and the appropriate reviewing authority 
(paragraph 3.0(b)) for any application specific guidance that is beyond 
the scope of this section.

                             8.2 Source Data

                            8.2.1 Discussion

    a. Sources of pollutants can be classified as point, line, area, and 
volume sources. Point sources are defined in terms of size and may vary 
between regulatory programs. The line sources most frequently considered 
are roadways and streets along which there are well-defined movements of 
motor vehicles. They may also be lines of roof vents or stacks, such as 
in aluminum refineries. Area and volume sources are often collections of 
a multitude of minor sources with individually small emissions that are 
impractical to consider as separate point or line sources. Large area 
sources are typically treated as a grid network of square areas, with 
pollutant emissions distributed uniformly within each grid square. 
Generally, input data requirements for air quality models necessitate 
the use of metric units. As necessary, any English units common to 
engineering applications should be appropriately converted to metric.
    b. For point sources, there are many source characteristics and 
operating conditions that may be needed to appropriately model the 
facility. For example, the plant layout (e.g., location of stacks and 
buildings), stack parameters (e.g., height and diameter), boiler size 
and type, potential operating conditions, and pollution control 
equipment parameters. Such details are required inputs to air quality 
models and are needed to determine maximum potential impacts.
    c. Modeling mobile emissions from streets and highways requires data 
on the road layout, including the width of each traveled lane, the 
number of lanes, and the width of the median strip. Additionally, 
traffic patterns should be taken into account (e.g., daily cycles of 
rush hour, differences in weekday and weekend traffic volumes, and 
changes in the distribution of heavy-duty trucks and light-duty 
passenger vehicles), as these patterns will affect the types and amounts 
of pollutant emissions allocated to each lane and the height of 
emissions.
    d. Emission factors can be determined through source-specific 
testing and measurements (e.g., stack test data) from existing sources 
or provided from a manufacturing association or vendor. Additionally, 
emissions factors for a variety of source types are compiled in an EPA 
publication commonly known as AP-42.\89\ AP-42 also provides an 
indication of the quality and amount of data on which many of the 
factors are based. Other information concerning emissions is available 
in EPA publications relating to specific source categories. The 
appropriate reviewing authority (paragraph 3.0(b)) should be consulted 
to determine appropriate source definitions and for guidance concerning 
the determination of emissions from and techniques for modeling the 
various source types.

                           8.2.2 Requirements

    a. For SIP attainment demonstrations for the purpose of projecting 
future year NAAQS attainment for ozone, PM2.5, and regional 
haze reasonable progress goal analyses, emissions which reflect actual 
emissions during the base modeling year time period should be input to 
models for base year modeling. Emissions projections to future years 
should account for key variables such as growth due to increased or 
decreased activity, expected emissions controls due to regulations, 
settlement agreements or consent decrees, fuel switches, and any other 
relevant information. Guidance on emissions estimation techniques 
(including future year projections) for SIP attainment demonstrations is 
available.60 90
    b. For the purpose of SIP revisions for stationary point sources, 
the regulatory modeling of inert pollutants shall use the emissions 
input data shown in Table 8-1 for short-term and long-term NAAQS. To 
demonstrate compliance and/or establish the appropriate SIP emissions 
limits, Table 8-1 generally provides for the use of ``allowable'' 
emissions in the regulatory dispersion modeling of the stationary point 
source(s) of interest. In such modeling, these source(s) should be 
modeled sequentially with these loads for every hour of the year. As 
part of a cumulative impact analysis, Table 8-1 allows for the model 
user to account for actual operations in developing the emissions inputs 
for

[[Page 625]]

dispersion modeling of nearby sources, while other sources are best 
represented by air quality monitoring data. Consultation with the 
appropriate reviewing authority (paragraph 3.0(b)) is advisable on the 
establishment of the appropriate emissions inputs for regulatory 
modeling applications with respect to SIP revisions for stationary point 
sources.
    c. For the purposes of demonstrating NAAQS compliance in a PSD 
assessment, the regulatory modeling of inert pollutants shall use the 
emissions input data shown in Table 8-2 for short and long-term NAAQS. 
The new or modifying stationary point source shall be modeled with 
``allowable'' emissions in the regulatory dispersion modeling. As part 
of a cumulative impact analysis, Table 8-2 allows for the model user to 
account for actual operations in developing the emissions inputs for 
dispersion modeling of nearby sources, while other sources are best 
represented by air quality monitoring data. For purposes of situations 
involving emissions trading, refer to current EPA policy and guidance to 
establish input data. Consultation with the appropriate reviewing 
authority (paragraph 3.0(b)) is advisable on the establishment of the 
appropriate emissions inputs for regulatory modeling applications with 
respect to PSD assessments for a proposed new or modifying source.
    d. For stationary source applications, changes in operating 
conditions that affect the physical emission parameters (e.g., release 
height, initial plume volume, and exit velocity) shall be considered to 
ensure that maximum potential impacts are appropriately determined in 
the assessment. For example, the load or operating condition for point 
sources that causes maximum ground-level concentrations shall be 
established. As a minimum, the source should be modeled using the design 
capacity (100 percent load). If a source operates at greater than design 
capacity for periods that could result in violations of the NAAQS or PSD 
increments, this load should be modeled. Where the source operates at 
substantially less than design capacity, and the changes in the stack 
parameters associated with the operating conditions could lead to higher 
ground level concentrations, loads such as 50 percent and 75 percent of 
capacity should also be modeled. Malfunctions which may result in excess 
emissions are not considered to be a normal operating condition. They 
generally should not be considered in determining allowable emissions. 
However, if the excess emissions are the result of poor maintenance, 
careless operation, or other preventable conditions, it may be necessary 
to consider them in determining source impact. A range of operating 
conditions should be considered in screening analyses. The load causing 
the highest concentration, in addition to the design load, should be 
included in refined modeling.
    e. Emissions from mobile sources also have physical and temporal 
characteristics that should be appropriately accounted. For example, an 
appropriate emissions model shall be used to determine emissions 
profiles. Such emissions should include speciation specific for the 
vehicle types used on the roadway (e.g., light duty and heavy duty 
trucks), and subsequent parameterizations of the physical emissions 
characteristics (e.g., release height) should reflect those emissions 
sources. For long-term standards, annual average emissions may be 
appropriate, but for short-term standards, discrete temporal 
representation of emissions should be used (e.g., variations in weekday 
and weekend traffic or the diurnal rush-hour profile typical of many 
cities). Detailed information and data requirements for modeling mobile 
sources of pollution are provided in the user's manuals for each of the 
models applicable to mobile sources.61 63

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                      8.3 Background Concentrations

                            8.3.1 Discussion

    a. Background concentrations are essential in constructing the 
design concentration, or total air quality concentration, as part of a 
cumulative impact analysis for NAAQS and PSD increments (section 9.2.3). 
Background air quality should not include the ambient impacts of the 
project source under consideration. Instead, it should include:
    i. Nearby sources: These are individual sources located in the 
vicinity of the source(s) under consideration for emissions limits that 
are not adequately represented by ambient monitoring data. Typically, 
sources that cause a significant concentration gradient in the vicinity 
of the source(s) under consideration for emissions limits are not 
adequately represented by background ambient monitoring. The ambient 
contributions from these nearby sources are thereby accounted for by 
explicitly modeling their emissions (section 8.2).
    ii. Other sources: That portion of the background attributable to 
natural sources, other unidentified sources in the vicinity of the 
project, and regional transport contributions from more distant sources 
(domestic and international). The ambient contributions from these 
sources are typically accounted for through use of ambient monitoring 
data or, in some cases, regional-scale photochemical grid modeling 
results.
    b. The monitoring network used for developing background 
concentrations is expected to conform to the same quality assurance and 
other requirements as those networks established for PSD purposes.\91\ 
Accordingly, the air quality monitoring data should be of sufficient 
completeness and follow appropriate data validation procedures. These 
data should be adequately representative of the area to inform 
calculation of the design concentration for comparison to the applicable 
NAAQS (section 9.2.2).

[[Page 628]]

    c. For photochemical grid modeling conducted in SIP attainment 
demonstrations for ozone, PM2.5 and regional haze, the 
emissions from nearby and other sources are included as model inputs and 
fully accounted for in the modeling application and predicted 
concentrations. The concept of adding individual components to develop a 
design concentration, therefore, do not apply in these SIP applications. 
However, such modeling results may then be appropriate for consideration 
in characterizing background concentrations for other regulatory 
applications. Also, as noted in section 5, this modeling approach does 
provide for an appropriate atmospheric environment to assess single-
source impacts for ozone and secondary PM2.5.
    d. For NAAQS assessments and SIP attainment demonstrations for inert 
pollutants, the development of the appropriate background concentration 
for a cumulative impact analysis involves proper accounting of each 
contribution to the design concentration and will depend upon whether 
the project area's situation consists of either an isolated single 
source(s) or a multitude of sources. For PSD increment assessments, all 
impacts after the appropriate baseline dates (i.e., trigger date, major 
source baseline date, and minor source baseline date) from all 
increment-consuming and increment-expanding sources should be considered 
in the design concentration (section 9.2.2).

            8.3.2 Recommendations for Isolated Single Sources

    a. In areas with an isolated source(s), determining the appropriate 
background concentration should focus on characterization of 
contributions from all other sources through adequately representative 
ambient monitoring data.
    b. The EPA recommends use of the most recent quality assured air 
quality monitoring data collected in the vicinity of the source to 
determine the background concentration for the averaging times of 
concern. In most cases, the EPA recommends using data from the monitor 
closest to and upwind of the project area. If several monitors are 
available, preference should be given to the monitor with 
characteristics that are most similar to the project area. If there are 
no monitors located in the vicinity of the new or modifying source, a 
``regional site'' may be used to determine background concentrations. A 
regional site is one that is located away from the area of interest but 
is impacted by similar or adequately representative sources.
    c. Many of the challenges related to cumulative impact analyses 
arise in the context of defining the appropriate metric to characterize 
background concentrations from ambient monitoring data and determining 
the appropriate method for combining this monitor-based background 
contribution to the modeled impact of the project and other nearby 
sources. For many cases, the best starting point would be use of the 
current design value for the applicable NAAQS as a uniform monitored 
background contribution across the project area. However, there are 
cases in which the current design value may not be appropriate. Such 
cases include but are not limited to:
    i. For situations involving a modifying source where the existing 
facility is determined to impact the ambient monitor, the background 
concentration at each monitor can be determined by excluding values when 
the source in question is impacting the monitor. In such cases, 
monitoring sites inside a 90[deg] sector downwind of the source may be 
used to determine the area of impact.
    ii. There may be other circumstances which would necessitate 
modifications to the ambient data record. Such cases could include 
removal of data from specific days or hours when a monitor is being 
impacted by activities that are not typical or not expected to occur 
again in the future (e.g., construction, roadway repairs, forest fires, 
or unusual agricultural activities). There may also be cases where it 
may be appropriate to scale (multiplying the monitored concentrations 
with a scaling factor) or adjust (adding or subtracting a constant value 
the monitored concentrations) data from specific days or hours. Such 
adjustments would make the monitored background concentrations more 
temporally and/or spatially representative of the area around the new or 
modifying source for the purposes of the regulatory assessment.
    iii. For short-term standards, the diurnal or seasonal patterns of 
the air quality monitoring data may differ significantly from the 
patterns associated with the modeled concentrations. When this occurs, 
it may be appropriate to pair the air quality monitoring data in a 
temporal manner that reflects these patterns (e.g., pairing by season 
and/or hour of day).\92\
    iv. For situations where monitored air quality concentrations vary 
across the modeling domain, it may be appropriate to consider air 
quality monitoring data from multiple monitors within the project area.
    d. Determination of the appropriate background concentrations should 
be consistent with appropriate EPA modeling guidance 59 60 
and justified in the modeling protocol that is vetted with the 
appropriate reviewing authority (paragraph 3.0(b)).
    e. Considering the spatial and temporal variability throughout a 
typical modeling domain on an hourly basis and the complexities and 
limitations of hourly observations from the ambient monitoring network, 
the EPA does not recommend hourly or daily pairing of monitored 
background and modeled concentrations except in rare cases of

[[Page 629]]

relatively isolated sources where the available monitor can be shown to 
be representative of the ambient concentration levels in the areas of 
maximum impact from the proposed new source. The implicit assumption 
underlying hourly pairing is that the background monitored levels for 
each hour are spatially uniform and that the monitored values are fully 
representative of background levels at each receptor for each hour. Such 
an assumption clearly ignores the many factors that contribute to the 
temporal and spatial variability of ambient concentrations across a 
typical modeling domain on an hourly basis. In most cases, the seasonal 
(or quarterly) pairing of monitored and modeled concentrations should 
sufficiently address situations to which the impacts from modeled 
emissions are not temporally correlated with background monitored 
levels.
    f. In those cases where adequately representative monitoring data to 
characterize background concentrations are not available, it may be 
appropriate to use results from a regional-scale photochemical grid 
model, or other representative model application, as background 
concentrations consistent with the considerations discussed above and in 
consultation with the appropriate reviewing authority (paragraph 
3.0(b)).

              8.3.3 Recommendations for Multi-Source Areas

    a. In multi-source areas, determining the appropriate background 
concentration involves: (1) Identification and characterization of 
contributions from nearby sources through explicit modeling, and (2) 
characterization of contributions from other sources through adequately 
representative ambient monitoring data. A key point here is the 
interconnectedness of each component in that the question of which 
nearby sources to include in the cumulative modeling is inextricably 
linked to the question of what the ambient monitoring data represents 
within the project area.
    b. Nearby sources: All sources in the vicinity of the source(s) 
under consideration for emissions limits that are not adequately 
represented by ambient monitoring data should be explicitly modeled. 
Since an ambient monitor is limited to characterizing air quality at a 
fixed location, sources that cause a significant concentration gradient 
in the vicinity of the source(s) under consideration for emissions 
limits are not likely to be adequately characterized by the monitored 
data due to the high degree of variability of the source's impact.
    i. The pattern of concentration gradients can vary significantly 
based on the averaging period being assessed. In general, concentration 
gradients will be smaller and more spatially uniform for annual averages 
than for short-term averages, especially for hourly averages. The 
spatial distribution of annual impacts around a source will often have a 
single peak downwind of the source based on the prevailing wind 
direction, except in cases where terrain or other geographic effects are 
important. By contrast, the spatial distribution of peak short-term 
impacts will typically show several localized concentration peaks with 
more significant gradient.
    ii. Concentration gradients associated with a particular source will 
generally be largest between that source's location and the distance to 
the maximum ground-level concentrations from that source. Beyond the 
maximum impact distance, concentration gradients will generally be much 
smaller and more spatially uniform. Thus, the magnitude of a 
concentration gradient will be greatest in the proximity of the source 
and will generally not be significant at distances greater than 10 times 
the height of the stack(s) at that source without consideration of 
terrain influences.
    iii. The number of nearby sources to be explicitly modeled in the 
air quality analysis is expected to be few except in unusual situations. 
In most cases, the few nearby sources will be located within the first 
10 to 20 km from the source(s) under consideration. Owing to both the 
uniqueness of each modeling situation and the large number of variables 
involved in identifying nearby sources, no attempt is made here to 
comprehensively define a ``significant concentration gradient.'' Rather, 
identification of nearby sources calls for the exercise of professional 
judgment by the appropriate reviewing authority (paragraph 3.0(b)). This 
guidance is not intended to alter the exercise of that judgment or to 
comprehensively prescribe which sources should be included as nearby 
sources.
    c. For cumulative impact analyses of short-term and annual ambient 
standards, the nearby sources as well as the project source(s) must be 
evaluated using an appropriate appendix A model or approved alternative 
model with the emission input data shown in Table 8-1 or 8-2.
    i. When modeling a nearby source that does not have a permit and the 
emissions limits contained in the SIP for a particular source category 
is greater than the emissions possible given the source's maximum 
physical capacity to emit, the ``maximum allowable emissions limit'' for 
such a nearby source may be calculated as the emissions rate 
representative of the nearby source's maximum physical capacity to emit, 
considering its design specifications and allowable fuels and process 
materials. However, the burden is on the permit applicant to 
sufficiently document what the maximum physical capacity to emit is for 
such a nearby source.

[[Page 630]]

    ii. It is appropriate to model nearby sources only during those 
times when they, by their nature, operate at the same time as the 
primary source(s) or could have impact on the averaging period of 
concern. Accordingly, it is not necessary to model impacts of a nearby 
source that does not, by its nature, operate at the same time as the 
primary source or could have impact on the averaging period of concern, 
regardless of an identified significant concentration gradient from the 
nearby source. The burden is on the permit applicant to adequately 
justify the exclusion of nearby sources to the satisfaction of the 
appropriate reviewing authority (paragraph 3.0(b)). The following 
examples illustrate two cases in which a nearby source may be shown not 
to operate at the same time as the primary source(s) being modeled: (1) 
Seasonal sources (only used during certain seasons of the year). Such 
sources would not be modeled as nearby sources during times in which 
they do not operate; and (2) Emergency backup generators, to the extent 
that they do not operate simultaneously with the sources that they back 
up. Such emergency equipment would not be modeled as nearby sources.
    d. Other sources. That portion of the background attributable to all 
other sources (e.g., natural sources, minor and distant major sources) 
should be accounted for through use of ambient monitoring data and 
determined by the procedures found in section 8.3.2 in keeping with 
eliminating or reducing the source-oriented impacts from nearby sources 
to avoid potential double-counting of modeled and monitored 
contributions.

                      8.4 Meteorological Input Data

                            8.4.1 Discussion

    a. This subsection covers meteorological input data for use in 
dispersion modeling for regulatory applications and is separate from 
recommendations made for photochemical grid modeling. Recommendations 
for meteorological data for photochemical grid modeling applications are 
outlined in the latest version of EPA's Modeling Guidance for 
Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and 
Regional Haze.\60\ In cases where Lagrangian models are applied for 
regulatory purposes, appropriate meteorological inputs should be 
determined in consultation with the appropriate reviewing authority 
(paragraph 3.0(b)).
    b. The meteorological data used as input to a dispersion model 
should be selected on the basis of spatial and climatological (temporal) 
representativeness as well as the ability of the individual parameters 
selected to characterize the transport and dispersion conditions in the 
area of concern. The representativeness of the measured data is 
dependent on numerous factors including, but not limited to: (1) The 
proximity of the meteorological monitoring site to the area under 
consideration; (2) the complexity of the terrain; (3) the exposure of 
the meteorological monitoring site; and (4) the period of time during 
which data are collected. The spatial representativeness of the data can 
be adversely affected by large distances between the source and 
receptors of interest and the complex topographic characteristics of the 
area. Temporal representativeness is a function of the year-to-year 
variations in weather conditions. Where appropriate, data 
representativeness should be viewed in terms of the appropriateness of 
the data for constructing realistic boundary layer profiles and, where 
applicable, three-dimensional meteorological fields, as described in 
paragraphs (c) and (d) of this subsection.
    c. The meteorological data should be adequately representative and 
may be site-specific data, data from a nearby National Weather Service 
(NWS) or comparable station, or prognostic meteorological data. The 
implementation of NWS Automated Surface Observing Stations (ASOS) in the 
early 1990's should not preclude the use of NWS ASOS data if such a 
station is determined to be representative of the modeled area.\93\
    d. Model input data are normally obtained either from the NWS or as 
part of a site-specific measurement program. State climatology offices, 
local universities, FAA, military stations, industry, and pollution 
control agencies may also be sources of such data. In specific cases, 
prognostic meteorological data may be appropriate for use and obtained 
from similar sources. Some recommendations and requirements for the use 
of each type of data are included in this subsection.

                 8.4.2 Recommendations and Requirements

    a. AERMET \94\ shall be used to preprocess all meteorological data, 
be it observed or prognostic, for use with AERMOD in regulatory 
applications. The AERMINUTE \95\ processor, in most cases, should be 
used to process 1-minute ASOS wind data for input to AERMET when 
processing NWS ASOS sites in AERMET. When processing prognostic 
meteorological data for AERMOD, the Mesoscale Model Interface Program 
(MMIF) \103\ should be used to process data for input to AERMET. Other 
methods of processing prognostic meteorological data for input to AERMET 
should be approved by the appropriate reviewing authority. Additionally, 
the following meteorological preprocessors are recommended by the EPA: 
PCRAMMET,\96\ MPRM,\97\ and METPRO.\98\ PCRAMMET is the recommended 
meteorological data preprocessor for use in applications of OCD 
employing hourly NWS data. MPRM is the recommended meteorological data 
preprocessor for applications of OCD employing site-specific 
meteorological data.

[[Page 631]]

METPRO is the recommended meteorological data preprocessor for use with 
CTDMPLUS.\99\
    b. Regulatory application of AERMOD necessitates careful 
consideration of the meteorological data for input to AERMET. Data 
representativeness, in the case of AERMOD, means utilizing data of an 
appropriate type for constructing realistic boundary layer profiles. Of 
particular importance is the requirement that all meteorological data 
used as input to AERMOD should be adequately representative of the 
transport and dispersion within the analysis domain. Where surface 
conditions vary significantly over the analysis domain, the emphasis in 
assessing representativeness should be given to adequate 
characterization of transport and dispersion between the source(s) of 
concern and areas where maximum design concentrations are anticipated to 
occur. The EPA recommends that the surface characteristics input to 
AERMET should be representative of the land cover in the vicinity of the 
meteorological data, i.e., the location of the meteorological tower for 
measured data or the representative grid cell for prognostic data. 
Therefore, the model user should apply the latest version 
AERSURFACE,100 101 where applicable, for determining surface 
characteristics when processing measured meteorological data through 
AERMET. In areas where it is not possible to use AERSURFACE output, 
surface characteristics can be determined using techniques that apply 
the same analysis as AERSURFACE. In the case of prognostic 
meteorological data, the surface characteristics associated with the 
prognostic meteorological model output for the representative grid cell 
should be used.102 103 Furthermore, since the spatial scope 
of each variable could be different, representativeness should be judged 
for each variable separately. For example, for a variable such as wind 
direction, the data should ideally be collected near plume height to be 
adequately representative, especially for sources located in complex 
terrain. Whereas, for a variable such as temperature, data from a 
station several kilometers away from the source may be considered to be 
adequately representative. More information about meteorological data, 
representativeness, and surface characteristics can be found in the 
AERMOD Implementation Guide.\76\
    c. Regulatory application of CTDMPLUS requires the input of multi-
level measurements of wind speed, direction, temperature, and turbulence 
from an appropriately sited meteorological tower. The measurements 
should be obtained up to the representative plume height(s) of interest. 
Plume heights of interest can be determined by use of screening 
procedures such as CTSCREEN.
    d. Regulatory application of OCD requires meteorological data over 
land and over water. The over land or surface data, processed through 
PCRAMMET \96\ or MPRM,\97\ that provides hourly stability class, wind 
direction and speed, ambient temperature, and mixing height, are 
required. Data over water requires hourly mixing height, relative 
humidity, air temperature, and water surface temperature. Missing winds 
are substituted with the surface winds. Vertical wind direction shear, 
vertical temperature gradient, and turbulence intensities are optional.
    e. The model user should acquire enough meteorological data to 
ensure that worst-case meteorological conditions are adequately 
represented in the model results. The use of 5 years of adequately 
representative NWS or comparable meteorological data, at least 1 year of 
site-specific, or at least 3 years of prognostic meteorological data, 
are required. If 1 year or more, up to 5 years, of site-specific data 
are available, these data are preferred for use in air quality analyses. 
Depending on completeness of the data record, consecutive years of NWS, 
site-specific, or prognostic data are preferred. Such data must be 
subjected to quality assurance procedures as described in section 
8.4.4.2.
    f. Objective analysis in meteorological modeling is to improve 
meteorological analyses (the ``first guess field'') used as initial 
conditions for prognostic meteorological models by incorporating 
information from meteorological observations. Direct and indirect (using 
remote sensing techniques) observations of temperature, humidity, and 
wind from surface and radiosonde reports are commonly employed to 
improve these analysis fields. For long-range transport applications, it 
is recommended that objective analysis procedures, using direct and 
indirect meteorological observations, be employed in preparing input 
fields to produce prognostic meteorological datasets. The length of 
record of observations should conform to recommendations outlined in 
paragraph 8.4.2(e) for prognostic meteorological model datasets.

                   8.4.3 National Weather Service Data

                           8.4.3.1 Discussion

    a. The NWS meteorological data are routinely available and familiar 
to most model users. Although the NWS does not provide direct 
measurements of all the needed dispersion model input variables, methods 
have been developed and successfully used to translate the basic NWS 
data to the needed model input. Site-specific measurements of model 
input parameters have been made for many modeling studies, and those 
methods and techniques are becoming more widely applied, especially in 
situations such as complex terrain applications, where available NWS 
data are not adequately representative.

[[Page 632]]

However, there are many modeling applications where NWS data are 
adequately representative and the applications still rely heavily on the 
NWS data.
    b. Many models use the standard hourly weather observations 
available from the National Centers for Environmental Information 
(NCEI).\b\ These observations are then preprocessed before they can be 
used in the models. Prior to the advent of ASOS in the early 1990's, the 
standard ``hourly'' weather observation was a human-based observation 
reflecting a single 2-minute average generally taken about 10 minutes 
before the hour. However, beginning in January 2000 for first-order 
stations and in March 2005 for all stations, the NCEI has archived the 
1-minute ASOS wind data (i.e., the rolling 2-minute average winds) for 
the NWS ASOS sites. The AERMINUTE processor \95\ was developed to reduce 
the number of calm and missing hours in AERMET processing by 
substituting standard hourly observations with full hourly average winds 
calculated from 1-minute ASOS wind data.
---------------------------------------------------------------------------

    \b\ Formerly the National Climatic Data Center (NCDC).
---------------------------------------------------------------------------

                         8.4.3.2 Recommendations

    a. The preferred models listed in appendix A all accept, as input, 
the NWS meteorological data preprocessed into model compatible form. If 
NWS data are judged to be adequately representative for a specific 
modeling application, they may be used. The NCEI makes available surface 
104 105 and upper air \106\ meteorological data online and in 
CD-ROM format. Upper air data are also available at the Earth System 
Research Laboratory Global Systems Divisions Web site (http://
esrl.noaa.gov/gsd).
    b. Although most NWS wind measurements are made at a standard height 
of 10 m, the actual anemometer height should be used as input to the 
preferred meteorological processor and model.
    c. Standard hourly NWS wind directions are reported to the nearest 
10 degrees. Due to the coarse resolution of these data, a specific set 
of randomly generated numbers has been developed by the EPA and should 
be used when processing standard hourly NWS data for use in the 
preferred EPA models to ensure a lack of bias in wind direction 
assignments within the models.
    d. Beginning with year 2000, NCEI began archiving 2-minute winds, 
reported every minute to the nearest degree for NWS ASOS sites. The 
AERMINUTE processor was developed to read those winds and calculate 
hourly average winds for input to AERMET. When such data are available 
for the NWS ASOS site being processed, the AERMINUTE processor should be 
used, in most cases, to calculate hourly average wind speed and 
direction when processing NWS ASOS data for input to AERMOD.\93\
    e. Data from universities, FAA, military stations, industry and 
pollution control agencies may be used if such data are equivalent in 
accuracy and detail (e.g., siting criteria, frequency of observations, 
data completeness, etc.) to the NWS data, they are judged to be 
adequately representative for the particular application, and have 
undergone quality assurance checks.
    f. After valid data retrieval requirements have been met,\107\ large 
number of hours in the record having missing data should be treated 
according to an established data substitution protocol provided that 
adequately representative alternative data are available. Data 
substitution guidance is provided in section 5.3 of reference.\107\ If 
no representative alternative data are available for substitution, the 
absent data should be coded as missing using missing data codes 
appropriate to the applicable meteorological pre-processor. Appropriate 
model options for treating missing data, if available in the model, 
should be employed.

                        8.4.4 Site-Specific Data

                           8.4.4.1 Discussion

    a. Spatial or geographical representativeness is best achieved by 
collection of all of the needed model input data in close proximity to 
the actual site of the source(s). Site-specific measured data are, 
therefore, preferred as model input, provided that appropriate 
instrumentation and quality assurance procedures are followed, and that 
the data collected are adequately representative (free from 
inappropriate local or microscale influences) and compatible with the 
input requirements of the model to be used. It should be noted that, 
while site-specific measurements are frequently made ``on-property'' 
(i.e., on the source's premises), acquisition of adequately 
representative site-specific data does not preclude collection of data 
from a location off property. Conversely, collection of meteorological 
data on a source's property does not of itself guarantee adequate 
representativeness. For help in determining representativeness of site-
specific measurements, technical guidance \107\ is available. Site-
specific data should always be reviewed for representativeness and 
adequacy by an experienced meteorologist, atmospheric scientist, or 
other qualified scientist in consultation with the appropriate reviewing 
authority (paragraph 3.0(b)).

                         8.4.4.2 Recommendations

    a. The EPA guidance \107\ provides recommendations on the collection 
and use of site-specific meteorological data. Recommendations on 
characteristics, siting, and exposure of meteorological instruments and 
on data recording, processing, completeness

[[Page 633]]

requirements, reporting, and archiving are also included. This 
publication should be used as a supplement to other limited guidance on 
these subjects.5 91 108 109 Detailed information on quality 
assurance is also available.\110\ As a minimum, site-specific 
measurements of ambient air temperature, transport wind speed and 
direction, and the variables necessary to estimate atmospheric 
dispersion should be available in meteorological datasets to be used in 
modeling. Care should be taken to ensure that meteorological instruments 
are located to provide an adequately representative characterization of 
pollutant transport between sources and receptors of interest. The 
appropriate reviewing authority (paragraph 3.0(b)) is available to help 
determine the appropriateness of the measurement locations.
    i. Solar radiation measurements. Total solar radiation or net 
radiation should be measured with a reliable pyranometer or net 
radiometer sited and operated in accordance with established site-
specific meteorological guidance.107 110
    ii. Temperature measurements. Temperature measurements should be 
made at standard shelter height (2m) in accordance with established 
site-specific meteorological guidance.\107\
    iii. Temperature difference measurements. Temperature difference 
(DT) measurements should be obtained using matched thermometers or a 
reliable thermocouple system to achieve adequate accuracy. Siting, probe 
placement, and operation of DT systems should be based on guidance found 
in Chapter 3 of reference 107 and such guidance should be followed when 
obtaining vertical temperature gradient data. AERMET may employ the Bulk 
Richardson scheme, which requires measurements of temperature 
difference, in lieu of cloud cover or insolation data. To ensure correct 
application and acceptance, AERMOD users should consult with the 
appropriate reviewing authority (paragraph 3.0(b)) before using the Bulk 
Richardson scheme for their analysis.
    iv. Wind measurements. For simulation of plume rise and dispersion 
of a plume emitted from a stack, characterization of the wind profile up 
through the layer in which the plume disperses is desirable. This is 
especially important in complex terrain and/or complex wind situations 
where wind measurements at heights up to hundreds of meters above stack 
base may be required in some circumstances. For tall stacks when site-
specific data are needed, these winds have been obtained traditionally 
using meteorological sensors mounted on tall towers. A feasible 
alternative to tall towers is the use of meteorological remote sensing 
instruments (e.g., acoustic sounders or radar wind profilers) to provide 
winds aloft, coupled with 10-meter towers to provide the near-surface 
winds. Note that when site-specific wind measurements are used, AERMOD, 
at a minimum, requires wind observations at a height above ground 
between seven times the local surface roughness height and 100 m. (For 
additional requirements for AERMOD and CTDMPLUS, see appendix A.) 
Specifications for wind measuring instruments and systems are contained 
in reference 107.
    b. All processed site-specific data should be in the form of hourly 
averages for input to the dispersion model.
    i. Turbulence data. There are several dispersion models that are 
capable of using direct measurements of turbulence (wind fluctuations) 
in the characterization of the vertical and lateral dispersion (e.g., 
CTDMPLUS or AERMOD). When turbulence data are used to directly 
characterize the vertical and lateral dispersion, the averaging time for 
the turbulence measurements should be 1 hour. For technical guidance on 
processing of turbulence parameters for use in dispersion modeling, 
refer to the user's guide to the meteorological processor for each model 
(see section 8.4.2(a)).
    ii. Stability categories. For dispersion models that employ P-G 
stability categories for the characterization of the vertical and 
lateral dispersion, the P-G stability categories, as originally defined, 
couple near-surface measurements of wind speed with subjectively 
determined insolation assessments based on hourly cloud cover and 
ceiling height observations. The wind speed measurements are made at or 
near 10 m. The insolation rate is typically assessed using observations 
of cloud cover and ceiling height based on criteria outlined by 
Turner.\72\ It is recommended that the P-G stability category be 
estimated using the Turner method with site-specific wind speed measured 
at or near 10 m and representative cloud cover and ceiling height. 
Implementation of the Turner method, as well as considerations in 
determining representativeness of cloud cover and ceiling height in 
cases for which site-specific cloud observations are unavailable, may be 
found in section 6 of reference 107. In the absence of requisite data to 
implement the Turner method, the solar radiation/delta-T (SRDT) method 
or wind fluctuation statistics (i.e., the [sigma]E and 
[sigma]A methods) may be used.
    iii. The SRDT method, described in section 6.4.4.2 of reference 107, 
is modified slightly from that published from earlier work\111\ and has 
been evaluated with three site-specific databases.\112\ The two methods 
of stability classification that use wind fluctuation statistics, the 
[sigma]E and [sigma]A methods, are also described 
in detail in section 6.4.4 of reference 107 (note applicable tables in 
section 6). For additional information on the wind fluctuation methods, 
several references are available.113 114 115 116
    c. Missing data substitution. After valid data retrieval 
requirements have been met,\107\

[[Page 634]]

hours in the record having missing data should be treated according to 
an established data substitution protocol provided that adequately 
representative alternative data are available. Such protocols are 
usually part of the approved monitoring program plan. Data substitution 
guidance is provided in section 5.3 of reference 107. If no 
representative alternative data are available for substitution, the 
absent data should be coded as missing, using missing data codes 
appropriate to the applicable meteorological pre-processor. Appropriate 
model options for treating missing data, if available in the model, 
should be employed.

                  8.4.5 Prognostic Meteorological Data

                           8.4.5.1 Discussion

    a. For some modeling applications, there may not be a representative 
NWS or comparable meteorological station available (e.g., complex 
terrain), and it may be cost prohibitive or infeasible to collect 
adequately representative site-specific data. For these cases, it may be 
appropriate to use prognostic meteorological data, if deemed adequately 
representative, in a regulatory modeling application. However, if 
prognostic meteorological data are not representative of transport and 
dispersion conditions in the area of concern, the collection of site-
specific data is necessary.
    b. The EPA has developed a processor, the MMIF,\102\ to process MM5 
(Mesoscale Model 5) or WRF (Weather Research and Forecasting) model data 
for input to various models including AERMOD. MMIF can process data for 
input to AERMET or AERMOD for a single grid cell or multiple grid cells. 
MMIF output has been found to compare favorably against observed data 
(site-specific or NWS).\117\ Specific guidance on processing MMIF for 
AERMOD can be found in reference 103. When using MMIF to process 
prognostic data for regulatory applications, the data should be 
processed to generate AERMET inputs and the data subsequently processed 
through AERMET for input to AERMOD. If an alternative method of 
processing data for input to AERMET is used, it must be approved by the 
appropriate reviewing authority (paragraph 3.0(b)).

                         8.4.5.2 Recommendations

    a. Prognostic model evaluation. Appropriate effort by the applicant 
should be devoted to the process of evaluating the prognostic 
meteorological data. The modeling data should be compared to NWS 
observational data or other comparable data in an effort to show that 
the data are adequately replicating the observed meteorological 
conditions of the time periods modeled. An operational evaluation of the 
modeling data for all model years (i.e., statistical, graphical) should 
be completed.\60\ The use of output from prognostic mesoscale 
meteorological models is contingent upon the concurrence with the 
appropriate reviewing authority (paragraph 3.0(b)) that the data are of 
acceptable quality, which can be demonstrated through statistical 
comparisons with meteorological observations aloft and at the surface at 
several appropriate locations.\60\
    b. Representativeness. When processing MMIF data for use with 
AERMOD, the grid cell used for the dispersion modeling should be 
adequately spatially representative of the analysis domain. In most 
cases, this may be the grid cell containing the emission source of 
interest. Since the dispersion modeling may involve multiple sources and 
the domain may cover several grid cells, depending on grid resolution of 
the prognostic model, professional judgment may be needed to select the 
appropriate grid cell to use. In such cases, the selected grid cells 
should be adequately representative of the entire domain.
    c. Grid resolution. The grid resolution of the prognostic 
meteorological data should be considered and evaluated appropriately, 
particularly for projects involving complex terrain. The operational 
evaluation of the modeling data should consider whether a finer grid 
resolution is needed to ensure that the data are representative. The use 
of output from prognostic mesoscale meteorological models is contingent 
upon the concurrence with the appropriate reviewing authority (paragraph 
3.0(b)) that the data are of acceptable quality.

                 8.4.6 Treatment of Near-Calms and Calms

                           8.4.6.1 Discussion

    a. Treatment of calm or light and variable wind poses a special 
problem in modeling applications since steady-state Gaussian plume 
models assume that concentration is inversely proportional to wind 
speed, depending on model formulations. Procedures have been developed 
to prevent the occurrence of overly conservative concentration estimates 
during periods of calms. These procedures acknowledge that a steady-
state Gaussian plume model does not apply during calm conditions, and 
that our knowledge of wind patterns and plume behavior during these 
conditions does not, at present, permit the development of a better 
technique. Therefore, the procedures disregard hours that are identified 
as calm. The hour is treated as missing and a convention for handling 
missing hours is recommended. With the advent of the AERMINUTE 
processor, when processing NWS ASOS data, the inclusion of hourly 
averaged winds from AERMINUTE will, in some instances, dramatically 
reduce the number of calm and missing hours, especially when the ASOS 
wind are derived from a sonic anemometer. To alleviate concerns

[[Page 635]]

about these issues, especially those introduced with AERMINUTE, the EPA 
implemented a wind speed threshold in AERMET for use with ASOS derived 
winds.93 94 Winds below the threshold will be treated as 
calms.
    b. AERMOD, while fundamentally a steady-state Gaussian plume model, 
contains algorithms for dealing with low wind speed (near calm) 
conditions. As a result, AERMOD can produce model estimates for 
conditions when the wind speed may be less than 1m/s, but still greater 
than the instrument threshold. Required input to AERMET for site-
specific data, the meteorological processor for AERMOD, includes a 
threshold wind speed and a reference wind speed. The threshold wind 
speed is the greater of the threshold of the instrument used to collect 
the wind speed data or wind direction sensor.\107\ The reference wind 
speed is selected by the model as the lowest level of non-missing wind 
speed and direction data where the speed is greater than the wind speed 
threshold, and the height of the measurement is between seven times the 
local surface roughness length and 100 m. If the only valid observation 
of the reference wind speed between these heights is less than the 
threshold, the hour is considered calm, and no concentration is 
calculated. None of the observed wind speeds in a measured wind profile 
that are less than the threshold speed are used in construction of the 
modeled wind speed profile in AERMOD.

                         8.4.6.2 Recommendations

    a. Hourly concentrations calculated with steady-state Gaussian plume 
models using calms should not be considered valid; the wind and 
concentration estimates for these hours should be disregarded and 
considered to be missing. Model predicted concentrations for 3-, 8-, and 
24-hour averages should be calculated by dividing the sum of the hourly 
concentrations for the period by the number of valid or non-missing 
hours. If the total number of valid hours is less than 18 for 24-hour 
averages, less than 6 for 8-hour averages, or less than 3 for 3-hour 
averages, the total concentration should be divided by 18 for the 24-
hour average, 6 for the 8-hour average, and 3 for the 3-hour average. 
For annual averages, the sum of all valid hourly concentrations is 
divided by the number of non-calm hours during the year. AERMOD has been 
coded to implement these instructions. For hours that are calm or 
missing, the AERMOD hourly concentrations will be zero. For other models 
listed in appendix A, a post-processor computer program, CALMPRO \118\ 
has been prepared, is available on the EPA's SCRAM Web site (section 
2.3), and should be used.
    b. Stagnant conditions that include extended periods of calms often 
produce high concentrations over wide areas for relatively long 
averaging periods. The standard steady-state Gaussian plume models are 
often not applicable to such situations. When stagnation conditions are 
of concern, other modeling techniques should be considered on a case-by-
case basis (see also section 7.2.1.2).
    c. When used in steady-state Gaussian plume models other than 
AERMOD, measured site-specific wind speeds of less than 1 m/s but higher 
than the response threshold of the instrument should be input as 1 m/s; 
the corresponding wind direction should also be input. Wind observations 
below the response threshold of the instrument should be set to zero, 
with the input file in ASCII format. For input to AERMOD, no such 
adjustment should be made to the site-specific wind data, as AERMOD has 
algorithms to account for light or variable winds as discussed in 
section 8.4.6.1(a). For NWS ASOS data, especially data using the 1-
minute ASOS winds, a wind speed threshold option is allowed with a 
recommended speed of 0.5 m/s.\93\ When using prognostic data processed 
by MMIF, a 0.5 m/s threshold is also invoked by MMIF for input to 
AERMET. Observations with wind speeds less than the threshold are 
considered calm, and no concentration is calculated. In all cases 
involving steady-state Gaussian plume models, calm hours should be 
treated as missing, and concentrations should be calculated as in 
paragraph (a) of this subsection.

                  9.0 Regulatory Application of Models

                             9.1 Discussion

    a. Standardized procedures are valuable in the review of air quality 
modeling and data analyses conducted to support SIP submittals and 
revisions, NSR, or other EPA requirements to ensure consistency in their 
regulatory application. This section recommends procedures specific to 
NSR that facilitate some degree of standardization while at the same 
time allowing the flexibility needed to assure the technically best 
analysis for each regulatory application. For SIP attainment 
demonstrations, refer to the appropriate EPA guidance 51 60 
for the recommended procedures.
    b. Air quality model estimates, especially with the support of 
measured air quality data, are the preferred basis for air quality 
demonstrations. A number of actions have been taken to ensure that the 
best air quality model is used correctly for each regulatory application 
and that it is not arbitrarily imposed.
     First, the Guideline clearly recommends that the 
most appropriate model be used in each case. Preferred models are 
identified, based on a number of factors, for many uses.

[[Page 636]]

     Second, the preferred models have been subjected 
to a systematic performance evaluation and a scientific peer review. 
Statistical performance measures, including measures of difference (or 
residuals) such as bias, variance of difference and gross variability of 
the difference, and measures of correlation such as time, space, and 
time and space combined, as described in section 2.1.1, were generally 
followed.
     Third, more specific information has been 
provided for considering the incorporation of new models into the 
Guideline (section 3.1), and the Guideline contains procedures for 
justifying the case-by-case use of alternative models and obtaining EPA 
approval (section 3.2).
    c. Air quality modeling is the preferred basis for air quality 
demonstrations. Nevertheless, there are rare circumstances where the 
performance of the preferred air quality model may be shown to be less 
than reasonably acceptable or where no preferred air quality model, 
screening model or technique, or alternative model are suitable for the 
situation. In these unique instances, there is the possibility of 
assuring compliance and establishing emissions limits for an existing 
source solely on the basis of observed air quality data in lieu of an 
air quality modeling analysis. Comprehensive air quality monitoring in 
the vicinity of the existing source with proposed modifications will be 
necessary in these cases. The same attention should be given to the 
detailed analyses of the air quality data as would be applied to a model 
performance evaluation.
    d. The current levels and forms of the NAAQS for the six criteria 
pollutants can be found on the EPA's NAAQS Web site at https://
www.epa.gov/criteria-air-pollutants. As required by the CAA, the NAAQS 
are subjected to extensive review every 5 years and the standards, 
including the level and the form, may be revised as part of that review. 
The criteria pollutants have either long-term (annual or quarterly) and/
or short-term (24-hour or less) forms that are not to be exceeded more 
than a certain frequency over a period of time (e.g., no exceedance on a 
rolling 3-month average, no more than once per year, or no more than 
once per year averaged over 3 years), are averaged over a period of time 
(e.g., an annual mean or an annual mean averaged over 3 years), or are 
some percentile that is averaged over a period of time (e.g., annual 
99th or 98th percentile averaged over 3 years). The 3-year period for 
ambient monitoring design values does not dictate the length of the data 
periods recommended for modeling (i.e., 5 years of NWS meteorological 
data, at least 1 year of site-specific, or at least 3 years of 
prognostic meteorological data).
    e. This section discusses general recommendations on the regulatory 
application of models for the purposes of NSR, including PSD permitting, 
and particularly for estimating design concentration(s), appropriately 
comparing these estimates to NAAQS and PSD increments, and developing 
emissions limits. This section also provides the criteria necessary for 
considering use of an analysis based on measured ambient data in lieu of 
modeling as the sole basis for demonstrating compliance with NAAQS and 
PSD increments.

                           9.2 Recommendations

                         9.2.1 Modeling Protocol

    a. Every effort should be made by the appropriate reviewing 
authority (paragraph 3.0(b)) to meet with all parties involved in either 
a SIP submission or revision or a PSD permit application prior to the 
start of any work on such a project. During this meeting, a protocol 
should be established between the preparing and reviewing parties to 
define the procedures to be followed, the data to be collected, the 
model to be used, and the analysis of the source and concentration data 
to be performed. An example of the content for such an effort is 
contained in the Air Quality Analysis Checklist posted on the EPA's 
SCRAM Web site (section 2.3). This checklist suggests the appropriate 
level of detail to assess the air quality resulting from the proposed 
action. Special cases may require additional data collection or analysis 
and this should be determined and agreed upon at the pre-application 
meeting. The protocol should be written and agreed upon by the parties 
concerned, although it is not intended that this protocol be a binding, 
formal legal document. Changes in such a protocol or deviations from the 
protocol are often necessary as the data collection and analysis 
progresses. However, the protocol establishes a common understanding of 
how the demonstration required to meet regulatory requirements will be 
made.

              9.2.2 Design Concentration and Receptor Sites

    a. Under the PSD permitting program, an air quality analysis for 
criteria pollutants is required to demonstrate that emissions from the 
construction or operation of a proposed new source or modification will 
not cause or contribute to a violation of the NAAQS or PSD increments.
    i. For a NAAQS assessment, the design concentration is the 
combination of the appropriate background concentration (section 8.3) 
with the estimated modeled impact of the proposed source. The NAAQS 
design concentration is then compared to the applicable NAAQS.
    ii. For a PSD increment assessment, the design concentration 
includes impacts occurring after the appropriate baseline date from all 
increment-consuming and increment-expanding sources. The PSD increment 
design

[[Page 637]]

concentration is then compared to the applicable PSD increment.
    b. The specific form of the NAAQS for the pollutant(s) of concern 
will also influence how the background and modeled data should be 
combined for appropriate comparison with the respective NAAQS in such a 
modeling demonstration. Given the potential for revision of the form of 
the NAAQS and the complexities of combining background and modeled data, 
specific details on this process can be found in the applicable modeling 
guidance available on the EPA's SCRAM Web site (section 2.3). Modeled 
concentrations should not be rounded before comparing the resulting 
design concentration to the NAAQS or PSD increments. Ambient monitoring 
and dispersion modeling address different issues and needs relative to 
each aspect of the overall air quality assessment.
    c. The PSD increments for criteria pollutants are listed in 40 CFR 
52.21(c) and 40 CFR 51.166(c). For short-term increments, these maximum 
allowable increases in pollutant concentrations may be exceeded once per 
year at each site, while the annual increment may not be exceeded. The 
highest, second-highest increase in estimated concentrations for the 
short-term averages, as determined by a model, must be less than or 
equal to the permitted increment. The modeled annual averages must not 
exceed the increment.
    d. Receptor sites for refined dispersion modeling should be located 
within the modeling domain (section 8.1). In designing a receptor 
network, the emphasis should be placed on receptor density and location, 
not total number of receptors. Typically, the density of receptor sites 
should be progressively more resolved near the new or modifying source, 
areas of interest, and areas with the highest concentrations with 
sufficient detail to determine where possible violations of a NAAQS or 
PSD increments are most likely to occur. The placement of receptor sites 
should be determined on a case-by-case basis, taking into consideration 
the source characteristics, topography, climatology, and monitor sites. 
Locations of particular importance include: (1) The area of maximum 
impact of the point source; (2) the area of maximum impact of nearby 
sources; and (3) the area where all sources combine to cause maximum 
impact. Depending on the complexities of the source and the environment 
to which the source is located, a dense array of receptors may be 
required in some cases. In order to avoid unreasonably large computer 
runs due to an excessively large array of receptors, it is often 
desirable to model the area twice. The first model run would use a 
moderate number of receptors more resolved near the new or modifying 
source and over areas of interest. The second model run would modify the 
receptor network from the first model run with a denser array of 
receptors in areas showing potential for high concentrations and 
possible violations, as indicated by the results of the first model run. 
Accordingly, the EPA neither anticipates nor encourages that numerous 
iterations of modeling runs be made to continually refine the receptor 
network.

  9.2.3 NAAQS and PSD Increments Compliance Demonstrations for New or 
                            Modifying Sources

    a. As described in this subsection, the recommended procedure for 
conducting either a NAAQS or PSD increments assessment under PSD 
permitting is a multi-stage approach that includes the following two 
stages:
    i. The EPA describes the first stage as a single-source impact 
analysis, since this stage involves considering only the impact of the 
new or modifying source. There are two possible levels of detail in 
conducting a single-source impact analysis with the model user beginning 
with use of a screening model and proceeding to use of a refined model 
as necessary.
    ii. The EPA describes the second stage as a cumulative impact 
analysis, since it takes into account all sources affecting the air 
quality in an area. In addition to the project source impact, this stage 
includes consideration of background, which includes contributions from 
nearby sources and other sources (e.g., natural, minor, and distant 
major sources).
    b. Each stage should involve increasing complexity and details, as 
required, to fully demonstrate that a new or modifying source will not 
cause or contribute to a violation of any NAAQS or PSD increment. As 
such, starting with a single-source impact analysis is recommended 
because, where the analysis at this stage is sufficient to demonstrate 
that a source will not cause or contribute to any potential violation, 
this may alleviate the need for a more time-consuming and comprehensive 
cumulative modeling analysis.
    c. The single-source impact analysis, or first stage of an air 
quality analysis, should begin by determining the potential of a 
proposed new or modifying source to cause or contribute to a NAAQS or 
PSD increment violation. In certain circumstances, a screening model or 
technique may be used instead of the preferred model because it will 
provide estimated worst-case ambient impacts from the proposed new or 
modifying source. If these worst case ambient concentration estimates 
indicate that the source will not cause or contribute to any potential 
violation of a NAAQS or PSD increment, then the screening analysis 
should generally be sufficient for the required demonstration under PSD. 
If the ambient concentration estimates indicate that the source's 
emissions have the potential to

[[Page 638]]

cause or contribute to a violation, then the use of a refined model to 
estimate the source's impact should be pursued. The refined modeling 
analysis should use a model or technique consistent with the Guideline 
(either a preferred model or technique or an alternative model or 
technique) and follow the requirements and recommendations for model 
inputs outlined in section 8. If the ambient concentration increase 
predicted with refined modeling indicates that the source will not cause 
or contribute to any potential violation of a NAAQS or PSD increment, 
then the refined analysis should generally be sufficient for the 
required demonstration under PSD. However, if the ambient concentration 
estimates from the refined modeling analysis indicate that the source's 
emissions have the potential to cause or contribute to a violation, then 
a cumulative impact analysis should be undertaken. The receptors that 
indicate the location of significant ambient impacts should be used to 
define the modeling domain for use in the cumulative impact analysis 
(section 8.2.2).
    d. The cumulative impact analysis, or the second stage of an air 
quality analysis, should be conducted with the same refined model or 
technique to characterize the project source and then include the 
appropriate background concentrations (section 8.3). The resulting 
design concentrations should be used to determine whether the source 
will cause or contribute to a NAAQS or PSD increment violation. This 
determination should be based on: (1) The appropriate design 
concentration for each applicable NAAQS (and averaging period); and (2) 
whether the source's emissions cause or contribute to a violation at the 
time and location of any modeled violation (i.e., when and where the 
predicted design concentration is greater than the NAAQS). For PSD 
increments, the cumulative impact analysis should also consider the 
amount of the air quality increment that has already been consumed by 
other sources, or, conversely, whether increment has expanded relative 
to the baseline concentration. Therefore, the applicant should model the 
existing or permitted nearby increment-consuming and increment-expanding 
sources, rather than using past modeling analyses of those sources as 
part of background concentration. This would permit the use of newly 
acquired data or improved modeling techniques if such data and/or 
techniques have become available since the last source was permitted.

          9.2.3.1 Considerations in Developing Emissions Limits

    a. Emissions limits and resulting control requirements should be 
established to provide for compliance with each applicable NAAQS (and 
averaging period) and PSD increment. It is possible that multiple 
emissions limits will be required for a source to demonstrate compliance 
with several criteria pollutants (and averaging periods) and PSD 
increments. Case-by-case determinations must be made as to the 
appropriate form of the limits, i.e., whether the emissions limits 
restrict the emission factor (e.g., limiting lb/MMBTU), the emission 
rate (e.g., lb/hr), or both. The appropriate reviewing authority 
(paragraph 3.0(b)) and appropriate EPA guidance should be consulted to 
determine the appropriate emissions limits on a case-by-case basis.

          9.2.4 Use of Measured Data in Lieu of Model Estimates

    a. As described throughout the Guideline, modeling is the preferred 
method for demonstrating compliance with the NAAQS and PSD increments 
and for determining the most appropriate emissions limits for new and 
existing sources. When a preferred model or adequately justified and 
approved alternative model is available, model results, including the 
appropriate background, are sufficient for air quality demonstrations 
and establishing emissions limits, if necessary. In instances when the 
modeling technique available is only a screening technique, the addition 
of air quality monitoring data to the analysis may lend credence to the 
model results. However, air quality monitoring data alone will normally 
not be acceptable as the sole basis for demonstrating compliance with 
the NAAQS and PSD increments or for determining emissions limits.
    b. There may be rare circumstances where the performance of the 
preferred air quality model will be shown to be less than reasonably 
acceptable when compared with air quality monitoring data measured in 
the vicinity of an existing source. Additionally, there may not be an 
applicable preferred air quality model, screening technique, or 
justifiable alternative model suitable for the situation. In these 
unique instances, there may be the possibility of establishing emissions 
limits and demonstrating compliance with the NAAQS and PSD increments 
solely on the basis of analysis of observed air quality data in lieu of 
an air quality modeling analysis. However, only in the case of a 
modification to an existing source should air quality monitoring data 
alone be a basis for determining adequate emissions limits or for 
demonstration that the modification will not cause or contribute to a 
violation of any NAAQS or PSD increment.
    c. The following items should be considered prior to the acceptance 
of an analysis of measured air quality data as the sole basis for an air 
quality demonstration or determining an emissions limit:
    i. Does a monitoring network exist for the pollutants and averaging 
times of concern in the vicinity of the existing source?

[[Page 639]]

    ii. Has the monitoring network been designed to locate points of 
maximum concentration?
    iii. Do the monitoring network and the data reduction and storage 
procedures meet EPA monitoring and quality assurance requirements?
    iv. Do the dataset and the analysis allow impact of the most 
important individual sources to be identified if more than one source or 
emission point is involved?
    v. Is at least one full year of valid ambient data available?
    vi. Can it be demonstrated through the comparison of monitored data 
with model results that available air quality models and techniques are 
not applicable?
    d. Comprehensive air quality monitoring in the area affected by the 
existing source with proposed modifications will be necessary in these 
cases. Additional meteorological monitoring may also be necessary. The 
appropriate number of air quality and meteorological monitors from a 
scientific and technical standpoint is a function of the situation being 
considered. The source configuration, terrain configuration, and 
meteorological variations all have an impact on number and optimal 
placement of monitors. Decisions on the monitoring network appropriate 
for this type of analysis can only be made on a case-by-case basis.
    e. Sources should obtain approval from the appropriate reviewing 
authority (paragraph 3.0(b)) and the EPA Regional Office for the 
monitoring network prior to the start of monitoring. A monitoring 
protocol agreed to by all parties involved is necessary to assure that 
ambient data are collected in a consistent and appropriate manner. The 
design of the network, the number, type, and location of the monitors, 
the sampling period, averaging time, as well as the need for 
meteorological monitoring or the use of mobile sampling or plume 
tracking techniques, should all be specified in the protocol and agreed 
upon prior to start-up of the network.
    f. Given the uniqueness and complexities of these rare 
circumstances, the procedures can only be established on a case-by-case 
basis for analyzing the source's emissions data and the measured air 
quality monitoring data, and for projecting with a reasoned basis the 
air quality impact of a proposed modification to an existing source in 
order to demonstrate that emissions from the construction or operation 
of the modification will not cause or contribute to a violation of the 
applicable NAAQS and PSD increment, and to determine adequate emissions 
limits. The same attention should be given to the detailed analyses of 
the air quality data as would be applied to a comprehensive model 
performance evaluation. In some cases, the monitoring data collected for 
use in the performance evaluation of preferred air quality models, 
screening technique, or existing alternative models may help inform the 
development of a suitable new alternative model. Early coordination with 
the appropriate reviewing authority (paragraph 3.0(b)) and the EPA 
Regional Office is fundamental with respect to any potential use of 
measured data in lieu of model estimates.

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          Industrial Source Applications. Part I: General Model 
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          evaluation of the PRIME plume rise and building downwash 
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          Ambient Air Monitors around Stationary Lead Sources. 
          Publication No. EPA-454/R-92-009R. Office of Air Quality 
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49. LEADPOST processor: https://www3.epa.gov/ttn/scram/models/aermod/
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84. Snyder, W.H. and R.E. Lawson, Jr., 1985. Fluid Modeling 
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91. U.S. Environmental Protection Agency, 1987. Ambient Air Monitoring 
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92. U.S. Environmental Protection Agency, 2011. Additional Clarification 
          Regarding Application of Appendix W Modeling Guidance for the 
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93. U.S. Environmental Protection Agency, 2013. Use of ASOS 
          meteorological data in AERMOD dispersion modeling. Memorandum 
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94. U.S. Environmental Protection Agency, 2016. User's Guide for the 
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          Standards, Research Triangle Park, NC.
95. U.S Environmental Protection Agency. 2016. AERMINUTE User's Guide. 
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96. U.S. Environmental Protection Agency, 1993. PCRAMMET User's Guide. 
          Publication No. EPA-454/R-96-001. Office of Air Quality 
          Planning and Standards, Research Triangle Park, NC. (NTIS No. 
          PB 97-147912).
97. U.S. Environmental Protection Agency, 1996. Meteorological Processor 
          for Regulatory Models (MPRM). Publication No. EPA-454/R-96-
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          Triangle Park, NC. (NTIS No. PB 96-180518).
98. Paine, R.J., 1987. User's Guide to the CTDM Meteorological 
          Preprocessor Program. Publication No. EPA-600/8-88-004. Office 
          of Research and Development, Research Triangle Park, NC. (NTIS 
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99. Perry, S.G., D.J. Burns, L.H. Adams, R.J. Paine, M.G. Dennis, M.T. 
          Mills, D.G. Strimaitis, R.J. Yamartino and E.M.

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          Insley, 1989. User's Guide to the Complex Terrain Dispersion 
          Model Plus Algorithms for Unstable Situations (CTDMPLUS). 
          Volume 1: Model Descriptions and User Instructions. 
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          89-181424).
100. U.S. Environmental Protection Agency, 2008. AERSURFACE User's 
          Guide. Publication No. EPA-454/B-08-001. Office of Air Quality 
          Planning and Standards, Research Triangle Park, NC.
101. Brode, R., K. Wesson, J. Thurman, and C. Tillerson, 2008. AERMOD 
          Sensitivity to the Choice of Surface Characteristics. Paper 
          811 presented at the 101st Air and Waste Management 
          Association Annual Conference and Exhibition, June 24-27, 
          2008, Portland, OR.
102. Environ, 2015. The Mesoscale Model Interface Program (MMIF) Version 
          3.2 User's Manual.
103. U.S. Environmental Protection Agency, 2016. Guidance on the Use of 
          the Mesoscale Model Interface Program (MMIF) for AERMOD 
          Applications. Publication No. EPA-454/B-16-003. Office of Air 
          Quality Planning and Standards, Research Triangle Park, NC.
104. Solar and Meteorological Surface Observation Network, 1961-1990; 3-
          volume CD-ROM. Version 1.0, September 1993. Produced jointly 
          by National Climatic Data Center and National Renewable Energy 
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105. Hourly United States Weather Observations, 1990-1995 (CD-ROM). 
          October 1997. Produced jointly by National Climatic Data 
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          www.ncdc.noaa.gov.
106. Radiosonde Data of North America, 1946-1996; 4-volume CD-ROM. 
          August 1996. Produced jointly by Forecast Systems laboratory 
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107. U.S. Environmental Protection Agency, 2000. Meteorological 
          Monitoring Guidance for Regulatory Modeling Applications. 
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          PB 2001-103606).
108. ASTM D5527: Standard Practice for Measuring Surface Winds and 
          Temperature by Acoustic Means. (2011).
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110. U.S. Environmental Protection Agency, 1995. Quality Assurance for 
          Air Pollution Measurement Systems, Volume IV--Meteorological 
          Measurements. Publication No. EPA600/R-94/038d. Office of Air 
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          Publications, 26 West Martin Luther King Dr., Cincinnati, OH 
          45268.
111. Bowen, B.M., J.M. Dewart and A.I. Chen, 1983. Stability Class 
          Determination: A Comparison for One Site. Proceedings, Sixth 
          Symposium on Turbulence and Diffusion. American Meteorological 
          Society, Boston, MA; pp. 211-214. (Docket No. A-92-65, II-A-
          7).
112. U.S. Environmental Protection Agency, 1993. An Evaluation of a 
          Solar Radiation/Delta-T (SRDT) Method for Estimating Pasquill-
          Gifford (P-G) Stability Categories. Publication No. EPA-454/R-
          93-055. Office of Air Quality Planning and Standards, Research 
          Triangle Park, NC. (NTIS No. PB 94-113958).
113. Irwin, J.S., 1980. Dispersion Estimate Suggestion 8: Estimation of 
          Pasquill Stability Categories. U.S. Environmental Protection 
          Agency, Office of Air Quality Planning and Standards, Research 
          Triangle Park, NC. (Docket No. A-80-46, II-B-10).
114. Mitchell, Jr., A.E. and K.O. Timbre, 1979. Atmospheric Stability 
          Class from Horizontal Wind Fluctuation. Presented at 72nd 
          Annual Meeting of Air Pollution Control Association, 
          Cincinnati, OH; June 24-29, 1979. (Docket No. A-80-46, II-P-
          9).
115. Smedman-Hogstrom, A. and V. Hogstrom, 1978. A Practical Method for 
          Determining Wind Frequency Distributions for the Lowest 200 m 
          from Routine Meteorological Data. Journal of Applied 
          Meteorology, 17(7): 942-954.
116. Smith, T.B. and S.M. Howard, 1972. Methodology for Treating 
          Diffusivity. MRI 72 FR-1030. Meteorology Research, Inc., 
          Altadena, CA. (Docket No. A-80-46, II-P-8).
117. U.S. Environmental Protection Agency, 2016. Evaluation of 
          Prognostic Meteorological Data in AERMOD Applications. 
          Publication No. EPA-454/R-16-004. Office of Air Quality 
          Planning and Standards, Research Triangle Park, NC.
118. U.S. Environmental Protection Agency, 1984. Calms Processor 
          (CALMPRO) User's Guide. Publication No. EPA-901/9-84-001. 
          Office of Air Quality Planning and Standards, Region I, 
          Boston, MA. (NTIS No. PB 84-229467).

Appendix A to Appendix W of Part 51--Summaries of Preferred Air Quality 
                                 Models

                            Table of Contents

A.0 Introduction and Availability

[[Page 645]]

A.1 AERMOD (AMS/EPA Regulatory Model)
A.2 CTDMPLUS (Complex Terrain Dispersion Model Plus Algorithms for 
          Unstable Situations)
A.3 OCD (Offshore and Coastal Dispersion Model)

                    A.0 Introduction and Availability

    (1) This appendix summarizes key features of refined air quality 
models preferred for specific regulatory applications. For each model, 
information is provided on availability, approximate cost (where 
applicable), regulatory use, data input, output format and options, 
simulation of atmospheric physics, and accuracy. These models may be 
used without a formal demonstration of applicability provided they 
satisfy the recommendations for regulatory use; not all options in the 
models are necessarily recommended for regulatory use.
    (2) Many of these models have been subjected to a performance 
evaluation using comparisons with observed air quality data. Where 
possible, several of the models contained herein have been subjected to 
evaluation exercises, including: (1) Statistical performance tests 
recommended by the American Meteorological Society, and (2) peer 
scientific reviews. The models in this appendix have been selected on 
the basis of the results of the model evaluations, experience with 
previous use, familiarity of the model to various air quality programs, 
and the costs and resource requirements for use.
    (3) Codes and documentation for all models listed in this appendix 
are available from the EPA's Support Center for Regulatory Air Models 
(SCRAM) Web site at https://www.epa.gov/scram. Codes and documentation 
may also available from the National Technical Information Service 
(NTIS), http://www.ntis.gov, and, when available, are referenced with 
the appropriate NTIS accession number.

                  A.1 AERMOD (AMS/EPA Regulatory Model)

                               References

U.S. Environmental Protection Agency, 2016. AERMOD Model Formulation. 
          Publication No. EPA-454/B-16-014. Office of Air Quality 
          Planning and Standards, Research Triangle Park, NC.
Cimorelli, A., et al., 2005. AERMOD: A Dispersion Model for Industrial 
          Source Applications. Part I: General Model Formulation and 
          Boundary Layer Characterization. Journal of Applied 
          Meteorology, 44(5): 682-693.
Perry, S. et al., 2005. AERMOD: A Dispersion Model for Industrial Source 
          Applications. Part II: Model Performance against 17 Field 
          Study Databases. Journal of Applied Meteorology, 44(5): 694-
          708.
U.S. Environmental Protection Agency, 2016. User's Guide for the AMS/EPA 
          Regulatory Model (AERMOD). Publication No. EPA-454/B-16-011. 
          Office of Air Quality Planning and Standards, Research 
          Triangle Park, NC.
U.S. Environmental Protection Agency, 2016. User's Guide for the AERMOD 
          Meteorological Preprocessor (AERMET). Publication No. EPA-454/
          B-16-010. Office of Air Quality Planning and Standards, 
          Research Triangle Park, NC.
U.S. Environmental Protection Agency, 2016. User's Guide for the AERMOD 
          Terrain Preprocessor (AERMAP). Publication No. EPA-454/B-16-
          012. U.S. Environmental Protection Agency, Office of Air 
          Quality Planning and Standards, Research Triangle Park, NC.
Schulman, L. L., D.G. Strimaitis and J.S. Scire, 2000. Development and 
          evaluation of the PRIME plume rise and building downwash 
          model. Journal of the Air and Waste Management Association, 
          50: 378-390.
Schulman, L. L., and Joseph S. Scire, 1980. Buoyant Line and Point 
          Source (BLP) Dispersion Model User's Guide. Document P-7304B. 
          Environmental Research and Technology, Inc., Concord, MA. 
          (NTIS No. PB 81-164642).

                              Availability

    The model codes and associated documentation are available on EPA's 
SCRAM Web site (paragraph A.0(3)).

                                Abstract

    AERMOD is a steady-state plume dispersion model for assessment of 
pollutant concentrations from a variety of sources. AERMOD simulates 
transport and dispersion from multiple point, area, or volume sources 
based on an up-to-date characterization of the atmospheric boundary 
layer. Sources may be located in rural or urban areas, and receptors may 
be located in simple or complex terrain. AERMOD accounts for building 
wake effects (i.e., plume downwash) based on the PRIME building downwash 
algorithms. The model employs hourly sequential preprocessed 
meteorological data to estimate concentrations for averaging times from 
1-hour to 1-year (also multiple years). AERMOD can be used to estimate 
the concentrations of nonreactive pollutants from highway traffic. 
AERMOD also handles unique modeling problems associated with aluminum 
reduction plants, and other industrial sources where plume rise and 
downwash effects from stationary buoyant line sources are important. 
AERMOD is designed to operate in concert with two pre-processor codes: 
AERMET processes meteorological data for input to AERMOD, and AERMAP 
processes

[[Page 646]]

terrain elevation data and generates receptor and hill height 
information for input to AERMOD.

                            a. Regulatory Use

    (1) AERMOD is appropriate for the following applications:
     Point, volume, and area sources;
     Buoyant, elevated line sources (e.g., aluminum 
reduction plants);
     Mobile sources;
     Surface, near-surface, and elevated releases;
     Rural or urban areas;
     Simple and complex terrain;
     Transport distances over which steady- state 
assumptions are appropriate, up to 50km;
     1-hour to annual averaging times; and
     Continuous toxic air emissions.
    (2) For regulatory applications of AERMOD, the regulatory default 
option should be set, i.e., the parameter DFAULT should be employed in 
the MODELOPT record in the COntrol Pathway. The DFAULT option requires 
the use of meteorological data processed with the regulatory options in 
AERMET, the use of terrain elevation data processed through the AERMAP 
terrain processor, stack-tip downwash, sequential date checking, and 
does not permit the use of the model in the SCREEN mode. In the 
regulatory default mode, pollutant half-life or decay options are not 
employed, except in the case of an urban source of sulfur dioxide where 
a 4-hour half-life is applied. Terrain elevation data from the U.S. 
Geological Survey (USGS) 7.5-Minute Digital Elevation Model (DEM), or 
equivalent (approx. 30-meter resolution), (processed through AERMAP) 
should be used in all applications. Starting in 2011, data from the 
National Elevation Dataset (NED, https://nationalmap.gov/elevation.html) 
can also be used in AERMOD, which includes a range of resolutions, from 
1-m to 2 arc seconds and such high resolution would always be preferred. 
In some cases, exceptions from the terrain data requirement may be made 
in consultation with the appropriate reviewing authority (paragraph 
3.0(b)).

                          b. Input Requirements

    (1) Source data: Required inputs include source type, location, 
emission rate, stack height, stack inside diameter, stack gas exit 
velocity, stack gas exit temperature, area and volume source dimensions, 
and source base elevation. For point sources subject to the influence of 
building downwash, direction-specific building dimensions (processed 
through the BPIPPRM building processor) should be input. Variable 
emission rates are optional. Buoyant line sources require coordinates of 
the end points of the line, release height, emission rate, average line 
source width, average building width, average spacing between buildings, 
and average line source buoyancy parameter. For mobile sources, traffic 
volume; emission factor, source height, and mixing zone width are needed 
to determine appropriate model inputs.
    (2) Meteorological data: The AERMET meteorological preprocessor 
requires input of surface characteristics, including surface roughness 
(zo), Bowen ratio, and albedo, as well as, hourly observations of wind 
speed between 7zo and 100 m (reference wind speed measurement from which 
a vertical profile can be developed), wind direction, cloud cover, and 
temperature between zo and 100 m (reference temperature measurement from 
which a vertical profile can be developed). Meteorological data can be 
in the form of observed data or prognostic modeled data as discussed in 
paragraph 8.4.1(d). Surface characteristics may be varied by wind sector 
and by season or month. When using observed meteorological data, a 
morning sounding (in National Weather Service format) from a 
representative upper air station is required. Latitude, longitude, and 
time zone of the surface, site-specific (if applicable) and upper air 
meteorological stations are required. The wind speed starting threshold 
is also required in AERMET for applications involving site-specific 
data. When using prognostic data, modeled profiles of temperature and 
winds are input to AERMET. These can be hourly or a time that represents 
a morning sounding. Additionally, measured profiles of wind, 
temperature, vertical and lateral turbulence may be required in certain 
applications (e.g., in complex terrain) to adequately represent the 
meteorology affecting plume transport and dispersion. Optionally, 
measurements of solar and/or net radiation may be input to AERMET. Two 
files are produced by the AERMET meteorological preprocessor for input 
to the AERMOD dispersion model. When using observed data, the surface 
file contains observed and calculated surface variables, one record per 
hour. For applications with multi-level site-specific meteorological 
data, the profile contains the observations made at each level of the 
meteorological tower (or remote sensor). When using prognostic data, the 
surface file contains surface variables calculated by the prognostic 
model and AERMET. The profile file contains the observations made at 
each level of a meteorological tower (or remote sensor), the one-level 
observations taken from other representative data (e.g., National 
Weather Service surface observations), one record per level per hour, or 
in the case of prognostic data, the prognostic modeled values of 
temperature and winds at user-specified levels.
    (i) Data used as input to AERMET should possess an adequate degree 
of representativeness to ensure that the wind, temperature and 
turbulence profiles derived by AERMOD

[[Page 647]]

are both laterally and vertically representative of the source impact 
area. The adequacy of input data should be judged independently for each 
variable. The values for surface roughness, Bowen ratio, and albedo 
should reflect the surface characteristics in the vicinity of the 
meteorological tower or representative grid cell when using prognostic 
data, and should be adequately representative of the modeling domain. 
Finally, the primary atmospheric input variables, including wind speed 
and direction, ambient temperature, cloud cover, and a morning upper air 
sounding, should also be adequately representative of the source area 
when using observed data.
    (ii) For applications involving the use of site-specific 
meteorological data that includes turbulences parameters (i.e., sigma-
theta and/or sigma-w), the application of the ADJ_U* option in AERMET 
would require approval as an alternative model application under section 
3.2.
    (iii) For recommendations regarding the length of meteorological 
record needed to perform a regulatory analysis with AERMOD, see section 
8.4.2.
    (3) Receptor data: Receptor coordinates, elevations, height above 
ground, and hill height scales are produced by the AERMAP terrain 
preprocessor for input to AERMOD. Discrete receptors and/or multiple 
receptor grids, Cartesian and/or polar, may be employed in AERMOD. 
AERMAP requires input of DEM or NED terrain data produced by the USGS, 
or other equivalent data. AERMAP can be used optionally to estimate 
source elevations.

                                c. Output

    Printed output options include input information, high concentration 
summary tables by receptor for user-specified averaging periods, maximum 
concentration summary tables, and concurrent values summarized by 
receptor for each day processed. Optional output files can be generated 
for: A listing of occurrences of exceedances of user-specified threshold 
value; a listing of concurrent (raw) results at each receptor for each 
hour modeled, suitable for post-processing; a listing of design values 
that can be imported into graphics software for plotting contours; a 
listing of results suitable for NAAQS analyses including NAAQS 
exceedances and culpability analyses; an unformatted listing of raw 
results above a threshold value with a special structure for use with 
the TOXX model component of TOXST; a listing of concentrations by rank 
(e.g., for use in quantile-quantile plots); and a listing of 
concentrations, including arc-maximum normalized concentrations, 
suitable for model evaluation studies.

                            d. Type of Model

    AERMOD is a steady-state plume model, using Gaussian distributions 
in the vertical and horizontal for stable conditions, and in the 
horizontal for convective conditions. The vertical concentration 
distribution for convective conditions results from an assumed bi-
Gaussian probability density function of the vertical velocity.

                           e. Pollutant Types

    AERMOD is applicable to primary pollutants and continuous releases 
of toxic and hazardous waste pollutants. Chemical transformation is 
treated by simple exponential decay.

                    f. Source-Receptor Relationships

    AERMOD applies user-specified locations for sources and receptors. 
Actual separation between each source-receptor pair is used. Source and 
receptor elevations are user input or are determined by AERMAP using 
USGS DEM or NED terrain data. Receptors may be located at user-specified 
heights above ground level.

                            g. Plume Behavior

    (1) In the convective boundary layer (CBL), the transport and 
dispersion of a plume is characterized as the superposition of three 
modeled plumes: (1) The direct plume (from the stack); (2) the indirect 
plume; and (3) the penetrated plume, where the indirect plume accounts 
for the lofting of a buoyant plume near the top of the boundary layer, 
and the penetrated plume accounts for the portion of a plume that, due 
to its buoyancy, penetrates above the mixed layer, but can disperse 
downward and re-enter the mixed layer. In the CBL, plume rise is 
superposed on the displacements by random convective velocities (Weil et 
al., 1997).
    (2) In the stable boundary layer, plume rise is estimated using an 
iterative approach to account for height-dependent lapse rates, similar 
to that in the CTDMPLUS model (see A.2 in this appendix).
    (3) Stack-tip downwash and buoyancy induced dispersion effects are 
modeled. Building wake effects are simulated for stacks subject to 
building downwash using the methods contained in the PRIME downwash 
algorithms (Schulman, et al., 2000). For plume rise affected by the 
presence of a building, the PRIME downwash algorithm uses a numerical 
solution of the mass, energy and momentum conservation laws (Zhang and 
Ghoniem, 1993). Streamline deflection and the position of the stack 
relative to the building affect plume trajectory and dispersion. 
Enhanced dispersion is based on the approach of Weil (1996). Plume mass 
captured by the cavity is well-mixed within the cavity. The captured 
plume mass is re-emitted to the far wake as a volume source.

[[Page 648]]

    (4) For elevated terrain, AERMOD incorporates the concept of the 
critical dividing streamline height, in which flow below this height 
remains horizontal, and flow above this height tends to rise up and over 
terrain (Snyder et al., 1985). Plume concentration estimates are the 
weighted sum of these two limiting plume states. However, consistent 
with the steady-state assumption of uniform horizontal wind direction 
over the modeling domain, straight-line plume trajectories are assumed, 
with adjustment in the plume/receptor geometry used to account for the 
terrain effects.

                           h. Horizontal Winds

    Vertical profiles of wind are calculated for each hour based on 
measurements and surface-layer similarity (scaling) relationships. At a 
given height above ground, for a given hour, winds are assumed constant 
over the modeling domain. The effect of the vertical variation in 
horizontal wind speed on dispersion is accounted for through simple 
averaging over the plume depth.

                         i. Vertical Wind Speed

    In convective conditions, the effects of random vertical updraft and 
downdraft velocities are simulated with a bi-Gaussian probability 
density function. In both convective and stable conditions, the mean 
vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Gaussian horizontal dispersion coefficients are estimated as 
continuous functions of the parameterized (or measured) ambient lateral 
turbulence and also account for buoyancy-induced and building wake-
induced turbulence. Vertical profiles of lateral turbulence are 
developed from measurements and similarity (scaling) relationships. 
Effective turbulence values are determined from the portion of the 
vertical profile of lateral turbulence between the plume height and the 
receptor height. The effective lateral turbulence is then used to 
estimate horizontal dispersion.

                         k. Vertical Dispersion

    In the stable boundary layer, Gaussian vertical dispersion 
coefficients are estimated as continuous functions of parameterized 
vertical turbulence. In the convective boundary layer, vertical 
dispersion is characterized by a bi-Gaussian probability density 
function and is also estimated as a continuous function of parameterized 
vertical turbulence. Vertical turbulence profiles are developed from 
measurements and similarity (scaling) relationships. These turbulence 
profiles account for both convective and mechanical turbulence. 
Effective turbulence values are determined from the portion of the 
vertical profile of vertical turbulence between the plume height and the 
receptor height. The effective vertical turbulence is then used to 
estimate vertical dispersion.

                       l. Chemical Transformation

    Chemical transformations are generally not treated by AERMOD. 
However, AERMOD does contain an option to treat chemical transformation 
using simple exponential decay, although this option is typically not 
used in regulatory applications except for sources of sulfur dioxide in 
urban areas. Either a decay coefficient or a half-life is input by the 
user. Note also that the Plume Volume Molar Ratio Method and the Ozone 
Limiting Method (section 4.2.3.4) for NO2 analyses are 
available.

                           m. Physical Removal

    AERMOD can be used to treat dry and wet deposition for both gases 
and particles.

                          n. Evaluation Studies

American Petroleum Institute, 1998. Evaluation of State of the Science 
          of Air Quality Dispersion Model, Scientific Evaluation, 
          prepared by Woodward-Clyde Consultants, Lexington, 
          Massachusetts, for American Petroleum Institute, Washington, 
          DC 20005-4070.
Brode, R.W., 2002. Implementation and Evaluation of PRIME in AERMOD. 
          Preprints of the 12th Joint Conference on Applications of Air 
          Pollution Meteorology, May 20-24, 2002; American 
          Meteorological Society, Boston, MA.
Brode, R.W., 2004. Implementation and Evaluation of Bulk Richardson 
          Number Scheme in AERMOD. 13th Joint Conference on Applications 
          of Air Pollution Meteorology, August 23-26, 2004; American 
          Meteorological Society, Boston, MA.
U.S. Environmental Protection Agency, 2003. AERMOD: Latest Features and 
          Evaluation Results. Publication No. EPA-454/R-03-003. Office 
          of Air Quality Planning and Standards, Research Triangle Park, 
          NC.
Heist, D., et al, 2013. Estimating near-road pollutant dispersion: A 
          model inter-comparison. Transportation Research Part D: 
          Transport and Environment, 25: pp 93-105.

   A.2 CTDMPLUS (Complex Terrain Dispersion Model Plus Algorithms for 
                          Unstable Situations)

                               References

Perry, S.G., D.J. Burns, L.H. Adams, R.J. Paine, M.G. Dennis, M.T. 
          Mills, D.G. Strimaitis, R.J. Yamartino and E.M. Insley, 1989. 
          User's Guide to the Complex Terrain Dispersion Model Plus 
          Algorithms for Unstable Situations

[[Page 649]]

          (CTDMPLUS). Volume 1: Model Descriptions and User 
          Instructions. EPA Publication No. EPA-600/8-89-041. U.S. 
          Environmental Protection Agency, Research Triangle Park, NC. 
          (NTIS No. PB 89-181424).
Perry, S.G., 1992. CTDMPLUS: A Dispersion Model for Sources near Complex 
          Topography. Part I: Technical Formulations. Journal of Applied 
          Meteorology, 31(7): 633-645.

                              Availability

    The model codes and associated documentation are available on the 
EPA's SCRAM Web site (paragraph A.0(3)).

                                Abstract

    CTDMPLUS is a refined point source Gaussian air quality model for 
use in all stability conditions for complex terrain applications. The 
model contains, in its entirety, the technology of CTDM for stable and 
neutral conditions. However, CTDMPLUS can also simulate daytime, 
unstable conditions, and has a number of additional capabilities for 
improved user friendliness. Its use of meteorological data and terrain 
information is different from other EPA models; considerable detail for 
both types of input data is required and is supplied by preprocessors 
specifically designed for CTDMPLUS. CTDMPLUS requires the 
parameterization of individual hill shapes using the terrain 
preprocessor and the association of each model receptor with a 
particular hill.

                            a. Regulatory Use

    CTDMPLUS is appropriate for the following applications:
     Elevated point sources;
     Terrain elevations above stack top;
     Rural or urban areas;
     Transport distances less than 50 kilometers; and
     1-hour to annual averaging times when used with a 
post-processor program such as CHAVG.

                          b. Input Requirements

    (1) Source data: For each source, user supplies source location, 
height, stack diameter, stack exit velocity, stack exit temperature, and 
emission rate; if variable emissions are appropriate, the user supplies 
hourly values for emission rate, stack exit velocity, and stack exit 
temperature.
    (2) Meteorological data: For applications of CTDMPLUS, multiple 
level (typically three or more) measurements of wind speed and 
direction, temperature and turbulence (wind fluctuation statistics) are 
required to create the basic meteorological data file (``PROFILE''). 
Such measurements should be obtained up to the representative plume 
height(s) of interest (i.e., the plume height(s) under those conditions 
important to the determination of the design concentration). The 
representative plume height(s) of interest should be determined using an 
appropriate complex terrain screening procedure (e.g., CTSCREEN) and 
should be documented in the monitoring/modeling protocol. The necessary 
meteorological measurements should be obtained from an appropriately 
sited meteorological tower augmented by SODAR and/or RASS if the 
representative plume height(s) of interest is above the levels 
represented by the tower measurements. Meteorological preprocessors then 
create a SURFACE data file (hourly values of mixed layer heights, 
surface friction velocity, Monin-Obukhov length and surface roughness 
length) and a RAWINsonde data file (upper air measurements of pressure, 
temperature, wind direction, and wind speed).
    (3) Receptor data: Receptor names (up to 400) and coordinates, and 
hill number (each receptor must have a hill number assigned).
    (4) Terrain data: User inputs digitized contour information to the 
terrain preprocessor which creates the TERRAIN data file (for up to 25 
hills).

                                c. Output

    (1) When CTDMPLUS is run, it produces a concentration file, in 
either binary or text format (user's choice), and a list file containing 
a verification of model inputs, i.e.,
     Input meteorological data from ``SURFACE'' and 
``PROFILE,''
     Stack data for each source,
     Terrain information,
     Receptor information, and
     Source-receptor location (line printer map).
    (2) In addition, if the case-study option is selected, the listing 
includes:
     Meteorological variables at plume height,
     Geometrical relationships between the source and 
the hill, and
     Plume characteristics at each receptor, i.e.,

--Distance in along-flow and cross flow direction
--Effective plume-receptor height difference
--Effective [sigma]y & [sigma]z values, both flat terrain and hill 
induced (the difference shows the effect of the hill)
--Concentration components due to WRAP, LIFT and FLAT.

    (3) If the user selects the TOPN option, a summary table of the top 
four concentrations at each receptor is given. If the ISOR option is 
selected, a source contribution table for every hour will be printed.
    (4) A separate output file of predicted (1-hour only) concentrations 
(``CONC'') is written if the user chooses this option. Three forms of 
output are possible:

[[Page 650]]

    (i) A binary file of concentrations, one value for each receptor in 
the hourly sequence as run;
    (ii) A text file of concentrations, one value for each receptor in 
the hourly sequence as run; or
    (iii) A text file as described above, but with a listing of receptor 
information (names, positions, hill number) at the beginning of the 
file.
    (5) Hourly information provided to these files besides the 
concentrations themselves includes the year, month, day, and hour 
information as well as the receptor number with the highest 
concentration.

                            d. Type of Model

    CTDMPLUS is a refined steady-state, point source plume model for use 
in all stability conditions for complex terrain applications.

                           e. Pollutant Types

    CTDMPLUS may be used to model non- reactive, primary pollutants.

                     f. Source-Receptor Relationship

    Up to 40 point sources, 400 receptors and 25 hills may be used. 
Receptors and sources are allowed at any location. Hill slopes are 
assumed not to exceed 15[deg], so that the linearized equation of motion 
for Boussinesq flow are applicable. Receptors upwind of the impingement 
point, or those associated with any of the hills in the modeling domain, 
require separate treatment.

                            g. Plume Behavior

    (1) As in CTDM, the basic plume rise algorithms are based on Briggs' 
(1975) recommendations.
    (2) A central feature of CTDMPLUS for neutral/stable conditions is 
its use of a critical dividing-streamline height (Hc) to 
separate the flow in the vicinity of a hill into two separate layers. 
The plume component in the upper layer has sufficient kinetic energy to 
pass over the top of the hill while streamlines in the lower portion are 
constrained to flow in a horizontal plane around the hill. Two separate 
components of CTDMPLUS compute ground-level concentrations resulting 
from plume material in each of these flows.
    (3) The model calculates on an hourly (or appropriate steady 
averaging period) basis how the plume trajectory (and, in stable/neutral 
conditions, the shape) is deformed by each hill. Hourly profiles of wind 
and temperature measurements are used by CTDMPLUS to compute plume rise, 
plume penetration (a formulation is included to handle penetration into 
elevated stable layers, based on Briggs (1984)), convective scaling 
parameters, the value of Hc, and the Froude number above 
Hc.

                           h. Horizontal Winds

    CTDMPLUS does not simulate calm meteorological conditions. Both 
scalar and vector wind speed observations can be read by the model. If 
vector wind speed is unavailable, it is calculated from the scalar wind 
speed. The assignment of wind speed (either vector or scalar) at plume 
height is done by either:
     Interpolating between observations above and 
below the plume height, or
     Extrapolating (within the surface layer) from the 
nearest measurement height to the plume height.

                         i. Vertical Wind Speed

    Vertical flow is treated for the plume component above the critical 
dividing streamline height (Hc); see ``Plume Behavior.''

                        j. Horizontal Dispersion

    Horizontal dispersion for stable/neutral conditions is related to 
the turbulence velocity scale for lateral fluctuations, [sigma]v, for 
which a minimum value of 0.2 m/s is used. Convective scaling 
formulations are used to estimate horizontal dispersion for unstable 
conditions.

                         k. Vertical Dispersion

    Direct estimates of vertical dispersion for stable/neutral 
conditions are based on observed vertical turbulence intensity, e.g., 
[sigma]w (standard deviation of the vertical velocity fluctuation). In 
simulating unstable (convective) conditions, CTDMPLUS relies on a 
skewed, bi-Gaussian probability density function (pdf) description of 
the vertical velocities to estimate the vertical distribution of 
pollutant concentration.

                       l. Chemical Transformation

    Chemical transformation is not treated by CTDMPLUS.

                           m. Physical Removal

    Physical removal is not treated by CTDMPLUS (complete reflection at 
the ground/hill surface is assumed).

                          n. Evaluation Studies

Burns, D.J., L.H. Adams and S.G. Perry, 1990. Testing and Evaluation of 
          the CTDMPLUS Dispersion Model: Daytime Convective Conditions. 
          U.S. Environmental Protection Agency, Research Triangle Park, 
          NC.
Paumier, J.O., S.G. Perry and D.J. Burns, 1990. An Analysis of CTDMPLUS 
          Model Predictions with the Lovett Power Plant Data Base. U.S. 
          Environmental Protection Agency, Research Triangle Park, NC.
Paumier, J.O., S.G. Perry and D.J. Burns, 1992. CTDMPLUS: A Dispersion 
          Model for Sources near Complex Topography. Part

[[Page 651]]

          II: Performance Characteristics. Journal of Applied 
          Meteorology, 31(7): 646-660.

             A.3 OCD (Offshore and Coastal Dispersion Model)

                                Reference

DiCristofaro, D.C. and S.R. Hanna, 1989. OCD: The Offshore and Coastal 
          Dispersion Model, Version 4. Volume I: User's Guide, and 
          Volume II: Appendices. Sigma Research Corporation, Westford, 
          MA. (NTIS Nos. PB 93-144384 and PB 93-144392).

                              Availability

    The model codes and associated documentation are available on EPA's 
SCRAM Web site (paragraph A.0(3)).

                                Abstract

    (1) OCD is a straight-line Gaussian model developed to determine the 
impact of offshore emissions from point, area or line sources on the air 
quality of coastal regions. OCD incorporates overwater plume transport 
and dispersion as well as changes that occur as the plume crosses the 
shoreline. Hourly meteorological data are needed from both offshore and 
onshore locations. These include water surface temperature, overwater 
air temperature, mixing height, and relative humidity.
    (2) Some of the key features include platform building downwash, 
partial plume penetration into elevated inversions, direct use of 
turbulence intensities for plume dispersion, interaction with the 
overland internal boundary layer, and continuous shoreline fumigation.

                            a. Regulatory Use

    OCD has been recommended for use by the Bureau of Ocean Energy 
Management for emissions located on the Outer Continental Shelf (50 FR 
12248; 28 March 1985). OCD is applicable for overwater sources where 
onshore receptors are below the lowest source height. Where onshore 
receptors are above the lowest source height, offshore plume transport 
and dispersion may be modeled on a case-by-case basis in consultation 
with the appropriate reviewing authority (paragraph 3.0(b)).

                          b. Input Requirements

    (1) Source data: Point, area or line source location, pollutant 
emission rate, building height, stack height, stack gas temperature, 
stack inside diameter, stack gas exit velocity, stack angle from 
vertical, elevation of stack base above water surface and gridded 
specification of the land/water surfaces. As an option, emission rate, 
stack gas exit velocity and temperature can be varied hourly.
    (2) Meteorological data: PCRAMMET is the recommended meteorological 
data preprocessor for use in applications of OCD employing hourly NWS 
data. MPRM is the recommended meteorological data preprocessor for 
applications of OCD employing site-specific meteorological data.
    (i) Over land: Surface weather data including hourly stability 
class, wind direction, wind speed, ambient temperature, and mixing 
height are required.
    (ii) Over water: Hourly values for mixing height, relative humidity, 
air temperature, and water surface temperature are required; if wind 
speed/direction are missing, values over land will be used (if 
available); vertical wind direction shear, vertical temperature 
gradient, and turbulence intensities are optional.
    (3) Receptor data: Location, height above local ground-level, 
ground-level elevation above the water surface.

                                c. Output

    (1) All input options, specification of sources, receptors and land/
water map including locations of sources and receptors.
    (2) Summary tables of five highest concentrations at each receptor 
for each averaging period, and average concentration for entire run 
period at each receptor.
    (3) Optional case study printout with hourly plume and receptor 
characteristics. Optional table of annual impact assessment from non-
permanent activities.
    (4) Concentration output files can be used by ANALYSIS postprocessor 
to produce the highest concentrations for each receptor, the cumulative 
frequency distributions for each receptor, the tabulation of all 
concentrations exceeding a given threshold, and the manipulation of 
hourly concentration files.

                            d. Type of Model

    OCD is a Gaussian plume model constructed on the framework of the 
MPTER model.

                           e. Pollutant Types

    OCD may be used to model primary pollutants. Settling and deposition 
are not treated.

                     f. Source-Receptor Relationship

    (1) Up to 250 point sources, 5 area sources, or 1 line source and 
180 receptors may be used.
    (2) Receptors and sources are allowed at any location.
    (3) The coastal configuration is determined by a grid of up to 3600 
rectangles. Each element of the grid is designated as either land or 
water to identify the coastline.

                            g. Plume Behavior

    (1) The basic plume rise algorithms are based on Briggs' 
recommendations.
    (2) Momentum rise includes consideration of the stack angle from the 
vertical.

[[Page 652]]

    (3) The effect of drilling platforms, ships, or any overwater 
obstructions near the source are used to decrease plume rise using a 
revised platform downwash algorithm based on laboratory experiments.
    (4) Partial plume penetration of elevated inversions is included 
using the suggestions of Briggs (1975) and Weil and Brower (1984).
    (5) Continuous shoreline fumigation is parameterized using the 
Turner method where complete vertical mixing through the thermal 
internal boundary layer (TIBL) occurs as soon as the plume intercepts 
the TIBL.

                           h. Horizontal Winds

    (1) Constant, uniform wind is assumed for each hour.
    (2) Overwater wind speed can be estimated from overland wind speed 
using relationship of Hsu (1981).
    (3) Wind speed profiles are estimated using similarity theory 
(Businger, 1973). Surface layer fluxes for these formulas are calculated 
from bulk aerodynamic methods.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    (1) Lateral turbulence intensity is recommended as a direct estimate 
of horizontal dispersion. If lateral turbulence intensity is not 
available, it is estimated from boundary layer theory. For wind speeds 
less than 8 m/s, lateral turbulence intensity is assumed inversely 
proportional to wind speed.
    (2) Horizontal dispersion may be enhanced because of obstructions 
near the source. A virtual source technique is used to simulate the 
initial plume dilution due to downwash.
    (3) Formulas recommended by Pasquill (1976) are used to calculate 
buoyant plume enhancement and wind direction shear enhancement.
    (4) At the water/land interface, the change to overland dispersion 
rates is modeled using a virtual source. The overland dispersion rates 
can be calculated from either lateral turbulence intensity or Pasquill-
Gifford curves. The change is implemented where the plume intercepts the 
rising internal boundary layer.

                         k. Vertical Dispersion

    (1) Observed vertical turbulence intensity is not recommended as a 
direct estimate of vertical dispersion. Turbulence intensity should be 
estimated from boundary layer theory as default in the model. For very 
stable conditions, vertical dispersion is also a function of lapse rate.
    (2) Vertical dispersion may be enhanced because of obstructions near 
the source. A virtual source technique is used to simulate the initial 
plume dilution due to downwash.
    (3) Formulas recommended by Pasquill (1976) are used to calculate 
buoyant plume enhancement.
    (4) At the water/land interface, the change to overland dispersion 
rates is modeled using a virtual source. The overland dispersion rates 
can be calculated from either vertical turbulence intensity or the 
Pasquill-Gifford coefficients. The change is implemented where the plume 
intercepts the rising internal boundary layer.

                       l. Chemical Transformation

    Chemical transformations are treated using exponential decay. 
Different rates can be specified by month and by day or night.

                           m. Physical Removal

    Physical removal is also treated using exponential decay.

                          n. Evaluation Studies

DiCristofaro, D.C. and S.R. Hanna, 1989. OCD: The Offshore and Coastal 
          Dispersion Model. Volume I: User's Guide. Sigma Research 
          Corporation, Westford, MA.
Hanna, S.R., L.L. Schulman, R.J. Paine and J.E. Pleim, 1984. The 
          Offshore and Coastal Dispersion (OCD) Model User's Guide, 
          Revised. OCS Study, MMS 84-0069. Environmental Research & 
          Technology, Inc., Concord, MA. (NTIS No. PB 86-159803).
Hanna, S.R., L.L. Schulman, R.J. Paine, J.E. Pleim and M. Baer, 1985. 
          Development and Evaluation of the Offshore and Coastal 
          Dispersion (OCD) Model. Journal of the Air Pollution Control 
          Association, 35: 1039-1047.
Hanna, S.R. and D.C. DiCristofaro, 1988. Development and Evaluation of 
          the OCD/API Model. Final Report, API Pub. 4461, American 
          Petroleum Institute, Washington, DC.

[82 FR 5203, Jan. 17, 2017]



   Sec. Appendix X to Part 51--Examples of Economic Incentive Programs

                       I. Introduction and Purpose

    This appendix contains examples of EIP's which are covered by the 
EIP rules. Program descriptions identify key provisions which 
distinguish the different model program types. The examples provide 
additional information and guidance on various types of regulatory 
programs collectively referred to as EIP's. The examples include 
programs involving stationary, area, and mobile sources. The definition 
section at 40 CFR 51.491 defines an EIP as a program which may include 
State established emission fees or a system of marketable permits, or a 
system of State fees on sale or manufacture of products the

[[Page 653]]

use of which contributes to O3 formation, or any combination 
of the foregoing or other similar measures, as well as incentives and 
requirements to reduce vehicle emissions and vehicle miles traveled in 
the area, including any of the transportation control measures 
identified in section 108(f). Such programs span a wide spectrum of 
program designs.
    The EIP's are comprised of several elements that, in combination 
with each other, must insure that the fundamental principles of any 
regulatory program (including accountability, enforceability and 
noninterference with other requirements of the Act) are met. There are 
many possible combinations of program elements that would be acceptable. 
Also, it is important to emphasize that the effectiveness of an EIP is 
dependent upon the particular area in which it is implemented. No two 
areas face the same air quality circumstances and, therefore, effective 
strategies and programs will differ among areas.
    Because of these considerations, the EPA is not specifying one 
particular design or type of strategy as acceptable for any given EIP. 
Such specific guidance would potentially discourage States (or other 
entities with delegated authority to administer parts of an 
implementation plan) from utilizing other equally viable program designs 
that may be more appropriate for their situation. Thus, the examples 
given in this Appendix are general in nature so as to avoid limiting 
innovation on the part of the States in developing programs tailored to 
individual State needs.
    Another important consideration in designing effective EIP's is the 
extent to which different strategies, or programs targeted at different 
types of sources, can complement one another when implemented together 
as an EIP ``package.'' The EPA encourages States to consider packaging 
different measures together when such a strategy is likely to increase 
the overall benefits from the program as a whole. Furthermore, some 
activities, such as information distribution or public awareness 
programs, while not EIP's in and of themselves, are often critical to 
the success of other measures and, therefore, would be appropriate 
complementary components of a program package. All SIP emissions 
reductions credits should reflect a consideration of the effectiveness 
of the entire package.

    II. Examples of Stationary and Mobile Source Economic Incentive 
                               Strategies

    There is a wide variety of programs that fall under the general 
heading of EIP's. Further, within each general type of program are 
several different basic program designs. This section describes common 
types of EIP's that have been implemented, designed, or discussed in the 
literature for stationary and mobile sources. The program types 
discussed below do not include all of the possible types of EIP's. 
Innovative approaches incorporating new ideas in existing programs, 
different combinations of existing program elements, or wholly new 
incentive systems provide additional opportunities for States to find 
ways to meet environmental goals at lower total cost.

                      A. Emissions Trading Markets

    One prominent class of EIP's is based upon the creation of a market 
in which trading of source-specific emissions requirements may occur. 
Such programs may include traditional rate-based emissions limits 
(generally referred to as emissions averaging) or overall limits on a 
source's total mass emissions per unit of time (generally referred to as 
an emissions cap). The emissions limits, which may be placed on 
individual emitting units or on facilities as a whole, may decline over 
time. The common feature of such programs is that sources have an 
ongoing incentive to reduce pollution and increased flexibility in 
meeting their regulatory requirements. A source may meet its own 
requirements either by directly preventing or controlling emissions or 
by trading or averaging with another source. Trading or averaging may 
occur within the same facility, within the same firm, or between 
different firms. Sources with lower cost abatement alternatives may 
provide the necessary emissions reductions to sources facing more 
expensive alternatives. These programs can lower the overall cost of 
meeting a given total level of abatement. All sources eligible to trade 
in an emissions market are faced with continuing incentives to find 
better ways of reducing emissions at the lowest possible cost, even if 
they are already meeting their own emissions requirements.
    Stationary, area, and mobile sources could be allowed to participate 
in a common emissions trading market. Programs involving emissions 
trading markets are particularly effective at reducing overall costs 
when individual affected sources face significantly different emissions 
control costs. A wider range in control costs among affected sources 
creates greater opportunities for cost-reducing trades. Thus, for 
example, areas which face relatively high stationary source control 
costs relative to mobile source control costs benefit most by including 
both stationary and mobile sources in a single emissions trading market.
    Programs involving emissions trading markets have generally been 
designated as either emission allowance or emission reduction credit 
(ERC) trading programs. The Federal Acid Rain Program is an example of 
an emission allowance trading program, while ``bubbles'' and ``generic 
bubbles'' created

[[Page 654]]

under the EPA's 1986 Emission Trading Policy Statement are examples of 
ERC trading. Allowance trading programs can establish emission 
allocations to be effective at the start of a program, at some specific 
time in the future, or at varying levels over time. An ERC trading 
program requires ERC's to be measured against a pre-established emission 
baseline. Allowance allocations or emission baselines can be established 
either directly by the EIP rules or by reference to traditional 
regulations (e.g., RACT requirements). In either type of program, 
sources can either meet their EIP requirements by maintaining their own 
emissions within the limits established by the program, or by buying 
surplus allowances or ERC's from other sources. In any case, the State 
will need to establish adequate enforceable procedures for certifying 
and tracking trades, and for monitoring and enforcing compliance with 
the EIP.
    The definition of the commodity to be traded and the design of the 
administrative procedures the buyer and seller must follow to complete a 
trade are obvious elements that must be carefully selected to help 
ensure a successful trading market that achieves the desired 
environmental goal at the lowest cost. An emissions market is defined as 
efficient if it achieves the environmental goal at the lowest possible 
total cost. Any feature of a program that unnecessarily increases the 
total cost without helping achieve the environmental goals causes market 
inefficiency. Thus, the design of an emission trading program should be 
evaluated not only in terms of the likelihood that the program design 
will ensure that the environmental goals of the program will be met, but 
also in terms of the costs that the design imposes upon market 
transactions and the impact of those costs on market efficiency.
    Transaction costs are the investment in time and resources to 
acquire information about the price and availability of allowances or 
ERC's, to negotiate a trade, and to assure the trade is properly 
recorded and legally enforceable. All trading markets impose some level 
of transaction costs. The level of transaction costs in an emissions 
trading market are affected by various aspects of the design of the 
market, such as the nature of the procedures for reviewing, approving, 
and recording trades, the timing of such procedures (i.e., before or 
after the trade is made), uncertainties in the value of the allowance or 
credit being traded, the legitimacy of the allowance or credit being 
offered for sale, and the long-term integrity of the market itself. 
Emissions trading programs in which every transaction is different, such 
as programs requiring significant consideration of the differences in 
the chemical properties or geographic location of the emissions, can 
result in higher transaction costs than programs with a standardized 
trading commodity and well-defined rules for acceptable trades. 
Transaction costs are also affected by the relative ease with which 
information can be obtained about the availability and price of 
allowances or credits.
    While the market considerations discussed above are clearly 
important in designing an efficient market to minimize the transaction 
costs of such a program, other considerations, such as regulatory 
certainty, enforcement issues, and public acceptance, also clearly need 
to be factored into the design of any emissions trading program.

                             B. Fee Programs

    A fee on each unit of emissions is a strategy that can provide a 
direct incentive for sources to reduce emissions. Ideally, fees should 
be set so as to result in emissions being reduced to the socially 
optimal level considering the costs of control and the benefits of the 
emissions reductions. In order to motivate a change in emissions, the 
fees must be high enough that sources will actively seek to reduce 
emissions. It is important to note that not all emission fee programs 
are designed to motivate sources to lower emissions. Fee programs using 
small fees are designed primarily to generate revenue, often to cover 
some of the administrative costs of a regulatory program.
    There can be significant variations in emission fee programs. For 
example, potential emissions could be targeted by placing a fee on an 
input (e.g., a fee on the quantity and BTU content of fuel used in an 
industrial boiler) rather than on actual emissions. Sources paying a fee 
on potential emissions could be eligible for a fee waiver or rebate by 
demonstrating that potential emissions are not actually emitted, such as 
through a carbon absorber system on a coating operation.
    Some fee program variations are designed to mitigate the potentially 
large amount of revenue that a fee program could generate. Although more 
complex than a simple fee program, programs that reduce or eliminate the 
total revenues may be more readily adopted in a SIP than a simple 
emission fee. Some programs lower the amount of total revenues generated 
by waiving the fee on some emissions. These programs reduce the total 
amount of revenue generated, while providing an incentive to decrease 
emissions. Alternatively, a program may impose higher per-unit fees on a 
portion of the emissions stream, providing a more powerful but targeted 
incentive at the same revenue levels. For example, fees could be 
collected on all emissions in excess of some fixed level. The level 
could be set as a percentage of a baseline (e.g., fees on emissions 
above some percentage of historical emissions), or as the lowest 
emissions possible (e.g., fees on emissions in excess of the lowest 
demonstrated emissions from the source category).

[[Page 655]]

    Other fee programs are ``revenue neutral,'' meaning that the 
pollution control agency does not receive any net revenues. One way to 
design a revenue-neutral program is to have both a fee provision and a 
rebate provision. Rebates must be carefully designed to avoid lessening 
the incentive provided by the emission fee. For example, a rebate based 
on comparing a source's actual emissions and the average emissions for 
the source category can be designed to be revenue neutral and not 
diminish the incentive.
    Other types of fee programs collect a fee in relation to particular 
activities or types of products to encourage the use of alternatives. 
While these fees are not necessarily directly linked to the total amount 
of emissions from the activity or product, the relative simplicity of a 
usage fee may make such programs an effective way to lower emissions. An 
area source example is a construction permit fee for wood stoves. Such a 
permit fee is directly related to the potential to emit inherent in a 
wood stove, and not to the actual emissions from each wood stove in use. 
Fees on raw materials to a manufacturing process can encourage product 
reformulation (e.g., fees on solvent sold to makers of architectural 
coatings) or changes in work practices (e.g., fees on specialty solvents 
and degreasing compounds used in manufacturing).
    Road pricing mechanisms are fee programs that are available to 
curtail low occupancy vehicle use, fund transportation system 
improvements and control measures, spatially and temporally shift 
driving patterns, and attempt to effect land usage changes. Primary 
examples include increased peak period roadway, bridge, or tunnel tolls 
(this could also be accomplished with automated vehicle identification 
systems as well), and toll discounts for pooling arrangements and zero-
emitting/low-emitting vehicles.

                    C. Tax Code and Zoning Provisions

    Modifications to existing State or local tax codes, zoning 
provisions, and land use planning can provide effective economic 
incentives. Possible modifications to encourage emissions reductions 
cover a broad span of programs, such as accelerated depreciation of 
capital equipment used for emissions reductions, corporate income tax 
deductions or credits for emission abatement costs, property tax waivers 
based on decreasing emissions, exempting low-emitting products from 
sales tax, and limitations on parking spaces for office facilities. 
Mobile source strategies include waiving or lowering any of the 
following for zero- or low-emitting vehicles: vehicle registration fees, 
vehicle property tax, sales tax, taxicab license fees, and parking 
taxes.

                              D. Subsidies

    A State may create incentives for reducing emissions by offering 
direct subsidies, grants or low-interest loans to encourage the purchase 
of lower-emitting capital equipment, or a switch to less polluting 
operating practices. Examples of such programs include clean vehicle 
conversions, starting shuttle bus or van pool programs, and mass transit 
fare subsidies. Subsidy programs often suffer from a variety of ``free 
rider'' problems. For instance, subsidies for people or firms who were 
going to switch to the cleaner alternative anyway lower the 
effectiveness of the subsidy program, or drive up the cost of achieving 
a targeted level of emissions reductions.

                   E. Transportation Control Measures

    The following measures are the TCM's listed in section 108(f):
    (i) Programs for improved public transit;
    (ii) Restriction of certain roads or lanes to, or construction of 
such roads or lanes for use by, passenger buses or high occupancy 
vehicles;
    (iii) Employer-based transportation management plans, including 
incentives;
    (iv) Trip-reduction ordinances;
    (v) Traffic flow improvement programs that achieve emission 
reductions;
    (vi) Fringe and transportation corridor parking facilities serving 
multiple-occupancy vehicle programs or transit service;
    (vii) Programs to limit or restrict vehicle use in downtown areas or 
other areas of emission concentration particularly during periods of 
peak use;
    (viii) Programs for the provision of all forms of high-occupancy, 
shared-ride services;
    (ix) Programs to limit portions of road surfaces or certain sections 
of the metropolitan area to the use of non-motorized vehicles or 
pedestrian use, both as to time and place;
    (x) Programs for secure bicycle storage facilities and other 
facilities, including bicycle lanes, for the convenience and protection 
of bicyclists, in both public and private areas;
    (xi) Programs to control extended idling of vehicles;
    (xii) Programs to reduce motor vehicle emissions, consistent with 
title II, which are caused by extreme cold start conditions;
    (xiii) Employer-sponsored programs to permit flexible work 
schedules;
    (xiv) Programs and ordinances to facilitate non-automobile travel, 
provision and utilization of mass transit, and to generally reduce the 
need for single-occupant vehicle travel, as part of transportation 
planning and development efforts of a locality, including programs and 
ordinances applicable to new shopping centers, special events, and other 
centers of vehicle activity;

[[Page 656]]

    (xv) Programs for new construction and major reconstruction of 
paths, tracks or areas solely for the use by pedestrian or other non-
motorized means of transportation when economically feasible and in the 
public interest. For purposes of this clause, the Administrator shall 
also consult with the Secretary of the Interior; and
    (xvi) Programs to encourage the voluntary removal from use and the 
marketplace of pre-1980 model year light-duty vehicles and pre-1980 
model light-duty trucks.

[59 FR 16715, Apr. 7, 1994]



Sec. Appendix Y to Part 51--Guidelines for BART Determinations Under the 
                           Regional Haze Rule

                            Table of Contents

I. Introduction and Overview
A. What is the purpose of the guidelines?
B. What does the CAA require generally for improving visibility?
C. What is the BART requirement in the CAA?
D. What types of visibility problems does EPA address in its 
regulations?
E. What are the BART requirements in EPA's regional haze regulations?
F. What is included in the guidelines?
G. Who is the target audience for the guidelines?
H. Do EPA regulations require the use of these guidelines?
II. How to Identify BART-eligible Sources
A. What are the steps in identifying BART-eligible sources?
1. Step 1: Identify emission units in the BART categories
2. Step 2: Identify the start-up dates of the emission units
3. Step 3: Compare the potential emissions to the 250 ton/yr cutoff
4. Final step: Identify the emission units and pollutants that 
constitute the BART-eligible source.
III. How to Identify Sources ``Subject to BART''
IV. The BART Determination: Analysis of BART Options
A. What factors must I address in the BART Analysis?
B. What is the scope of the BART review?
C. How does a BART review relate to maximum achievable control 
technology (MACT) standards under CAA section 112?
D. What are the five basic steps of a case-by-case BART analysis?
1. Step 1: How do I identify all available retrofit emission control 
techniques?
2. Step 2: How do I determine whether the options identified in Step 1 
are technically feasible?
3. Step 3: How do I evaluate technically feasible alternatives?
4. Step 4: For a BART review, what impacts am I expected to calculate 
and report? What methods does EPA recommend for the impacts analyses?
a. Impact analysis part 1: how do I estimate the costs of control?
b. What do we mean by cost effectiveness?
c. How do I calculate average cost effectiveness?
d. How do I calculate baseline emissions?
e. How do I calculate incremental cost effectiveness?
f. What other information should I provide in the cost impacts analysis?
g. What other things are important to consider in the cost impacts 
analysis?
h. Impact analysis part 2: How should I analyze and report energy 
impacts?
i. Impact analysis part 3: How do I analyze ``non-air quality 
environmental impacts?''
j. Impact analysis part 4: What are examples of non-air quality 
environmental impacts?
k. How do I take into account a project's ``remaining useful life'' in 
calculating control costs?
5. Step 5: How should I determine visibility impacts in the BART 
determination?
E. How do I select the ``best'' alternative, using the results of Steps 
1 through 5?
1. Summary of the impacts analysis
2. Selecting a ``best'' alternative
3. In selecting a ``best'' alternative, should I consider the 
affordability of controls?
4. SO2 limits for utility boilers
5. NOX limits for utility boilers
V. Enforceable Limits/Compliance Date

                      I. Introduction and Overview

                A. What is the purpose of the guidelines?

    The Clean Air Act (CAA), in sections 169A and 169B, contains 
requirements for the protection of visibility in 156 scenic areas across 
the United States. To meet the CAA's requirements, we published 
regulations to protect against a particular type of visibility 
impairment known as ``regional haze.'' The regional haze rule is found 
in this part at 40 CFR 51.300 through 51.309. These regulations require, 
in 40 CFR 51.308(e), that certain types of existing stationary sources 
of air pollutants install best available retrofit technology (BART). The 
guidelines are designed to help States and others (1) identify those 
sources that must comply with the BART requirement, and (2) determine 
the level of control technology that represents BART for each source.

    B. What does the CAA require generally for improving visibility?

    Section 169A of the CAA, added to the CAA by the 1977 amendments, 
requires States to protect and improve visibility in certain scenic 
areas of national importance. The scenic

[[Page 657]]

areas protected by section 169A are ``the mandatory Class I Federal 
Areas * * * where visibility is an important value.'' In these 
guidelines, we refer to these as ``Class I areas.'' There are 156 Class 
I areas, including 47 national parks (under the jurisdiction of the 
Department of Interior--National Park Service), 108 wilderness areas 
(under the jurisdiction of the Department of the Interior--Fish and 
Wildlife Service or the Department of Agriculture--U.S. Forest Service), 
and one International Park (under the jurisdiction of the Roosevelt-
Campobello International Commission). The Federal Agency with 
jurisdiction over a particular Class I area is referred to in the CAA as 
the Federal Land Manager. A complete list of the Class I areas is 
contained in 40 CFR 81.401 through 81.437, and you can find a map of the 
Class I areas at the following Internet site: http://www.epa.gov/ttn/
oarpg/t1/fr_notices/classimp.gif.
    The CAA establishes a national goal of eliminating man-made 
visibility impairment from all Class I areas. As part of the plan for 
achieving this goal, the visibility protection provisions in the CAA 
mandate that EPA issue regulations requiring that States adopt measures 
in their State implementation plans (SIPs), including long-term 
strategies, to provide for reasonable progress towards this national 
goal. The CAA also requires States to coordinate with the Federal Land 
Managers as they develop their strategies for addressing visibility.

               C. What is the BART requirement in the CAA?

    1. Under section 169A(b)(2)(A) of the CAA, States must require 
certain existing stationary sources to install BART. The BART provision 
applies to ``major stationary sources'' from 26 identified source 
categories which have the potential to emit 250 tons per year or more of 
any air pollutant. The CAA requires only sources which were put in place 
during a specific 15-year time interval to be subject to BART. The BART 
provision applies to sources that existed as of the date of the 1977 CAA 
amendments (that is, August 7, 1977) but which had not been in operation 
for more than 15 years (that is, not in operation as of August 7, 1962).
    2. The CAA requires BART review when any source meeting the above 
description ``emits any air pollutant which may reasonably be 
anticipated to cause or contribute to any impairment of visibility'' in 
any Class I area. In identifying a level of control as BART, States are 
required by section 169A(g) of the CAA to consider:
    (a) The costs of compliance,
    (b) The energy and non-air quality environmental impacts of 
compliance,
    (c) Any existing pollution control technology in use at the source,
    (d) The remaining useful life of the source, and
    (e) The degree of visibility improvement which may reasonably be 
anticipated from the use of BART.
    3. The CAA further requires States to make BART emission limitations 
part of their SIPs. As with any SIP revision, States must provide an 
opportunity for public comment on the BART determinations, and EPA's 
action on any SIP revision will be subject to judicial review.

      D. What types of visibility problems does EPA address in its 
                              regulations?

    1. We addressed the problem of visibility in two phases. In 1980, we 
published regulations addressing what we termed ``reasonably 
attributable'' visibility impairment. Reasonably attributable visibility 
impairment is the result of emissions from one or a few sources that are 
generally located in close proximity to a specific Class I area. The 
regulations addressing reasonably attributable visibility impairment are 
published in 40 CFR 51.300 through 51.307.
    2. On July 1, 1999, we amended these regulations to address the 
second, more common, type of visibility impairment known as ``regional 
haze.'' Regional haze is the result of the collective contribution of 
many sources over a broad region. The regional haze rule slightly 
modified 40 CFR 51.300 through 51.307, including the addition of a few 
definitions in Sec. 51.301, and added new Sec. Sec. 51.308 and 51.309.

  E. What are the BART requirements in EPA's regional haze regulations?

    1. In the July 1, 1999 rulemaking, we added a BART requirement for 
regional haze. We amended the BART requirements in 2005. You will find 
the BART requirements in 40 CFR 51.308(e). Definitions of terms used in 
40 CFR 51.308(e)(1) are found in 40 CFR 51.301.
    2. As we discuss in detail in these guidelines, the regional haze 
rule codifies and clarifies the BART provisions in the CAA. The rule 
requires that States identify and list ``BART-eligible sources,'' that 
is, that States identify and list those sources that fall within the 26 
source categories, were put in place during the 15-year window of time 
from 1962 to 1977, and have potential emissions greater than 250 tons 
per year. Once the State has identified the BART-eligible sources, the 
next step is to identify those BART-eligible sources that may ``emit any 
air pollutant which may reasonably be anticipated to cause or contribute 
to any impairment of visibility.'' Under the rule, a source which fits 
this description is ``subject to BART.'' For each source subject to 
BART, 40 CFR 51.308(e)(1)(ii)(A) requires that States identify the level 
of control representing BART after considering the factors set out in 
CAA section 169A(g), as follows:


[[Page 658]]


--States must identify the best system of continuous emission control 
technology for each source subject to BART taking into account the 
technology available, the costs of compliance, the energy and non-air 
quality environmental impacts of compliance, any pollution control 
equipment in use at the source, the remaining useful life of the source, 
and the degree of visibility improvement that may be expected from 
available control technology.

    3. After a State has identified the level of control representing 
BART (if any), it must establish an emission limit representing BART and 
must ensure compliance with that requirement no later than 5 years after 
EPA approves the SIP. States may establish design, equipment, work 
practice or other operational standards when limitations on measurement 
technologies make emission standards infeasible.

                 F. What is included in the guidelines?

    1. The guidelines provide a process for making BART determinations 
that States can use in implementing the regional haze BART requirements 
on a source-by-source basis, as provided in 40 CFR 51.308(e)(1). States 
must follow the guidelines in making BART determinations on a source-by-
source basis for 750 megawatt (MW) power plants but are not required to 
use the process in the guidelines when making BART determinations for 
other types of sources.
    2. The BART analysis process, and the contents of these guidelines, 
are as follows:
    (a) Identification of all BART-eligible sources. Section II of these 
guidelines outlines a step-by-step process for identifying BART-eligible 
sources.
    (b) Identification of sources subject to BART. As noted above, 
sources ``subject to BART'' are those BART-eligible sources which ``emit 
a pollutant which may reasonably be anticipated to cause or contribute 
to any impairment of visibility in any Class I area.'' We discuss 
considerations for identifying sources subject to BART in section III of 
the guidance.
    (c) The BART determination process. For each source subject to BART, 
the next step is to conduct an analysis of emissions control 
alternatives. This step includes the identification of available, 
technically feasible retrofit technologies, and for each technology 
identified, an analysis of the cost of compliance, the energy and non-
air quality environmental impacts, and the degree of visibility 
improvement in affected Class I areas resulting from the use of the 
control technology. As part of the BART analysis, the State should also 
take into account the remaining useful life of the source and any 
existing control technology present at the source. For each source, the 
State will determine a ``best system of continuous emission reduction'' 
based upon its evaluation of these factors. Procedures for the BART 
determination step are described in section IV of these guidelines.
    (d) Emissions limits. States must establish emission limits, 
including a deadline for compliance, consistent with the BART 
determination process for each source subject to BART. Considerations 
related to these limits are discussed in section V of these guidelines.

            G. Who is the target audience for the guidelines?

    1. The guidelines are written primarily for the benefit of State, 
local and Tribal agencies, and describe a process for making the BART 
determinations and establishing the emission limitations that must be 
included in their SIPs or Tribal implementation plans (TIPs). Throughout 
the guidelines, which are written in a question and answer format, we 
ask questions ``How do I * * *?'' and answer with phrases ``you should * 
* *, you must * * *'' The ``you'' means a State, local or Tribal agency 
conducting the analysis. We have used this format to make the guidelines 
simpler to understand, but we recognize that States have the authority 
to require source owners to assume part of the analytical burden, and 
that there will be differences in how the supporting information is 
collected and documented. We also recognize that data collection, 
analysis, and rule development may be performed by Regional Planning 
Organizations, for adoption within each SIP or TIP.
    2. The preamble to the 1999 regional haze rule discussed at length 
the issue of Tribal implementation of the requirements to submit a plan 
to address visibility. As explained there, requirements related to 
visibility are among the programs for which Tribes may be determined 
eligible and receive authorization to implement under the ``Tribal 
Authority Rule'' (``TAR'') (40 CFR 49.1 through 49.11). Tribes are not 
subject to the deadlines for submitting visibility implementation plans 
and may use a modular approach to CAA implementation. We believe there 
are very few BART-eligible sources located on Tribal lands. Where such 
sources exist, the affected Tribe may apply for delegation of 
implementation authority for this rule, following the process set forth 
in the TAR.

       H. Do EPA regulations require the use of these guidelines?

    Section 169A(b) requires us to issue guidelines for States to follow 
in establishing BART emission limitations for fossil-fuel fired power 
plants having a capacity in excess of 750 megawatts. This document 
fulfills that requirement, which is codified in 40

[[Page 659]]

CFR 51.308(e)(1)(ii)(B). The guidelines establish an approach to 
implementing the requirements of the BART provisions of the regional 
haze rule; we believe that these procedures and the discussion of the 
requirements of the regional haze rule and the CAA should be useful to 
the States. For sources other than 750 MW power plants, however, States 
retain the discretion to adopt approaches that differ from the 
guidelines.

                II. How To Identify BART-Eligible Sources

    This section provides guidelines on how to identify BART-eligible 
sources. A BART-eligible source is an existing stationary source in any 
of 26 listed categories which meets criteria for startup dates and 
potential emissions.

       A. What are the steps in identifying BART-eligible sources?

    Figure 1 shows the steps for identifying whether the source is a 
``BART-eligible source:''
    Step 1: Identify the emission units in the BART categories,
    Step 2: Identify the start-up dates of those emission units, and
    Step 3: Compare the potential emissions to the 250 ton/yr cutoff.
    Figure 1. How to determine whether a source is BART-eligible:
    Step 1: Identify emission units in the BART categories

Does the plant contain emissions units in one or more of the 26 source 
          categories?
 [rtarr2] No [rtarr2] Stop
 [rtarr2] Yes [rtarr2] Proceed to Step 2

    Step 2: Identify the start-up dates of these emission units

Do any of these emissions units meet the following two tests?
In existence on August 7, 1977
     AND
Began operation after August 7, 1962
 [rtarr2] No [rtarr2] Stop
 [rtarr2] Yes [rtarr2] Proceed to Step 3

    Step 3: Compare the potential emissions from these emission units to 
the 250 ton/yr cutoff

Identify the ``stationary source'' that includes the emission units you 
identified in Step 2.
Add the current potential emissions from all the emission units 
identified in Steps 1 and 2 that are included within the ``stationary 
source'' boundary.
Are the potential emissions from these units 250 tons per year or more 
for any visibility-impairing pollutant?
 [rtarr2] No [rtarr2] Stop
 [rtarr2] Yes [rtarr2] These emissions units comprise the ``BART-
eligible source.''

        1. Step 1: Identify Emission Units in the BART Categories

    1. The BART requirement only applies to sources in specific 
categories listed in the CAA. The BART requirement does not apply to 
sources in other source categories, regardless of their emissions. The 
listed categories are:
    (1) Fossil-fuel fired steam electric plants of more than 250 million 
British thermal units (BTU) per hour heat input,
    (2) Coal cleaning plants (thermal dryers),
    (3) Kraft pulp mills,
    (4) Portland cement plants,
    (5) Primary zinc smelters,
    (6) Iron and steel mill plants,
    (7) Primary aluminum ore reduction plants,
    (8) Primary copper smelters,
    (9) Municipal incinerators capable of charging more than 250 tons of 
refuse per day,
    (10) Hydrofluoric, sulfuric, and nitric acid plants,
    (11) Petroleum refineries,
    (12) Lime plants,
    (13) Phosphate rock processing plants,
    (14) Coke oven batteries,
    (15) Sulfur recovery plants,
    (16) Carbon black plants (furnace process),
    (17) Primary lead smelters,
    (18) Fuel conversion plants,
    (19) Sintering plants,
    (20) Secondary metal production facilities,
    (21) Chemical process plants,
    (22) Fossil-fuel boilers of more than 250 million BTUs per hour heat 
input,
    (23) Petroleum storage and transfer facilities with a capacity 
exceeding 300,000 barrels,
    (24) Taconite ore processing facilities,
    (25) Glass fiber processing plants, and
    (26) Charcoal production facilities.
    2. Some plants may have emission units from more than one category, 
and some emitting equipment may fit into more than one category. 
Examples of this situation are sulfur recovery plants at petroleum 
refineries, coke oven batteries and sintering plants at steel mills, and 
chemical process plants at refineries. For Step 1, you identify all of 
the emissions units at the plant that fit into one or more of the listed 
categories. You do not identify emission units in other categories.

    Example: A mine is collocated with an electric steam generating 
plant and a coal cleaning plant. You would identify emission units 
associated with the electric steam generating plant and the coal 
cleaning plant, because they are listed categories, but not the mine, 
because coal mining is not a listed category.

    3. The category titles are generally clear in describing the types 
of equipment to be listed. Most of the category titles are very broad 
descriptions that encompass all emission

[[Page 660]]

units associated with a plant site (for example, ``petroleum refining'' 
and ``kraft pulp mills''). This same list of categories appears in the 
PSD regulations. States and source owners need not revisit any 
interpretations of the list made previously for purposes of the PSD 
program. We provide the following clarifications for a few of the 
category titles:
    (1) ``Steam electric plants of more than 250 million BTU/hr heat 
input.'' Because the category refers to ``plants,'' we interpret this 
category title to mean that boiler capacities should be aggregated to 
determine whether the 250 million BTU/hr threshold is reached. This 
definition includes only those plants that generate electricity for 
sale. Plants that cogenerate steam and electricity also fall within the 
definition of ``steam electric plants''. Similarly, combined cycle 
turbines are also considered ``steam electric plants'' because such 
facilities incorporate heat recovery steam generators. Simple cycle 
turbines, in contrast, are not ``steam electric plants'' because these 
turbines typically do not generate steam.

    Example: A stationary source includes a steam electric plant with 
three 100 million BTU/hr boilers. Because the aggregate capacity exceeds 
250 million BTU/hr for the ``plant,'' these boilers would be identified 
in Step 2.

    (2) ``Fossil-fuel boilers of more than 250 million BTU/hr heat 
input.'' We interpret this category title to cover only those boilers 
that are individually greater than 250 million BTU/hr. However, an 
individual boiler smaller than 250 million BTU/hr should be subject to 
BART if it is an integral part of a process description at a plant that 
is in a different BART category--for example, a boiler at a Kraft pulp 
mill that, in addition to providing steam or mechanical power, uses the 
waste liquor from the process as a fuel. In general, if the process uses 
any by-product of the boiler and the boiler's function is to serve the 
process, then the boiler is integral to the process and should be 
considered to be part of the process description.
    Also, you should consider a multi-fuel boiler to be a ``fossil-fuel 
boiler'' if it burns any amount of fossil fuel. You may take federally 
and State enforceable operational limits into account in determining 
whether a multi-fuel boiler's fossil fuel capacity exceeds 250 million 
Btu/hr.
    (3) ``Petroleum storage and transfer facilities with a capacity 
exceeding 300,000 barrels.'' The 300,000 barrel cutoff refers to total 
facility-wide tank capacity for tanks that were put in place within the 
1962-1977 time period, and includes gasoline and other petroleum-derived 
liquids.
    (4) ``Phosphate rock processing plants.'' This category descriptor 
is broad, and includes all types of phosphate rock processing 
facilities, including elemental phosphorous plants as well as fertilizer 
production plants.
    (5) ``Charcoal production facilities.'' We interpret this category 
to include charcoal briquet manufacturing and activated carbon 
production.
    (6) ``Chemical process plants.'' and pharmaceutical manufacturing. 
Consistent with past policy, we interpret the category ``chemical 
process plants'' to include those facilities within the 2-digit Standard 
Industrial Classification (SIC) code 28. Accordingly, we interpret the 
term ``chemical process plants'' to include pharmaceutical manufacturing 
facilities.
    (7) ``Secondary metal production.'' We interpret this category to 
include nonferrous metal facilities included within SIC code 3341, and 
secondary ferrous metal facilities that we also consider to be included 
within the category ``iron and steel mill plants.''
    (8) ``Primary aluminum ore reduction.'' We interpret this category 
to include those facilities covered by 40 CFR 60.190, the new source 
performance standard (NSPS) for primary aluminum ore reduction plants. 
This definition is also consistent with the definition at 40 CFR 63.840.

      2. Step 2: Identify the Start-Up Dates of the Emission Units

    1. Emissions units listed under Step 1 are BART-eligible only if 
they were ``in existence'' on August 7, 1977 but were not ``in 
operation'' before August 7, 1962.

           What does ``in existence on August 7, 1977'' mean?

    2. The regional haze rule defines ``in existence'' to mean that:
    ``the owner or operator has obtained all necessary preconstruction 
approvals or permits required by Federal, State, or local air pollution 
emissions and air quality laws or regulations and either has (1) begun, 
or caused to begin, a continuous program of physical on-site 
construction of the facility or (2) entered into binding agreements or 
contractual obligations, which cannot be canceled or modified without 
substantial loss to the owner or operator, to undertake a program of 
construction of the facility to be completed in a reasonable time.'' 40 
CFR 51.301.
    As this definition is essentially identical to the definition of 
``commence construction'' as that term is used in the PSD regulations, 
the two terms mean the same thing. See 40 CFR 51.165(a)(1)(xvi) and 40 
CFR 52.21(b)(9). Under this definition, an emissions unit could be ``in 
existence'' even if it did not begin operating until several years after 
1977.

    Example: The owner of a source obtained all necessary permits in 
early 1977 and entered into binding construction agreements

[[Page 661]]

in June 1977. Actual on-site construction began in late 1978, and 
construction was completed in mid-1979. The source began operating in 
September 1979. The emissions unit was ``in existence'' as of August 7, 
1977.

    Major stationary sources which commenced construction AFTER August 
7, 1977 (i.e., major stationary sources which were not ``in existence'' 
on August 7, 1977) were subject to new source review (NSR) under the PSD 
program. Thus, the August 7, 1977 ``in existence'' test is essentially 
the same thing as the identification of emissions units that were 
grandfathered from the NSR review requirements of the 1977 CAA 
amendments.
    3. Sources are not BART-eligible if the only change at the plant 
during the relevant time period was the addition of pollution controls. 
For example, if the only change at a copper smelter during the 1962 
through 1977 time period was the addition of acid plants for the 
reduction of SO2 emissions, these emission controls would not 
by themselves trigger a BART review.

         What does ``in operation before August 7, 1962'' mean?

    An emissions unit that meets the August 7, 1977 ``in existence'' 
test is not BART-eligible if it was in operation before August 7, 1962. 
``In operation'' is defined as ``engaged in activity related to the 
primary design function of the source.'' This means that a source must 
have begun actual operations by August 7, 1962 to satisfy this test.

    Example: The owner or operator entered into binding agreements in 
1960. Actual on-site construction began in 1961, and construction was 
complete in mid-1962. The source began operating in September 1962. The 
emissions unit was not ``in operation'' before August 7, 1962 and is 
therefore subject to BART.

                   What is a ``reconstructed source?'

    1. Under a number of CAA programs, an existing source which is 
completely or substantially rebuilt is treated as a new source. Such 
``reconstructed'' sources are treated as new sources as of the time of 
the reconstruction. Consistent with this overall approach to 
reconstructions, the definition of BART-eligible facility (reflected in 
detail in the definition of ``existing stationary facility'') includes 
consideration of sources that were in operation before August 7, 1962, 
but were reconstructed during the August 7, 1962 to August 7, 1977 time 
period.
    2. Under the regional haze regulations at 40 CFR 51.301, a 
reconstruction has taken place if ``the fixed capital cost of the new 
component exceeds 50 percent of the fixed capital cost of a comparable 
entirely new source.'' The rule also states that ``[a]ny final decision 
as to whether reconstruction has occurred must be made in accordance 
with the provisions of Sec. Sec. 60.15 (f)(1) through (3) of this 
title.'' ``[T]he provisions of Sec. Sec. 60.15(f)(1) through (3)'' 
refers to the general provisions for New Source Performance Standards 
(NSPS). Thus, the same policies and procedures for identifying 
reconstructed ``affected facilities'' under the NSPS program must also 
be used to identify reconstructed ``stationary sources'' for purposes of 
the BART requirement.
    3. You should identify reconstructions on an emissions unit basis, 
rather than on a plantwide basis. That is, you need to identify only the 
reconstructed emission units meeting the 50 percent cost criterion. You 
should include reconstructed emission units in the list of emission 
units you identified in Step 1. You need consider as possible 
reconstructions only those emissions units with the potential to emit 
more than 250 tons per year of any visibility-impairing pollutant.
    4. The ``in operation'' and ``in existence'' tests apply to 
reconstructed sources. If an emissions unit was reconstructed and began 
actual operation before August 7, 1962, it is not BART-eligible. 
Similarly, any emissions unit for which a reconstruction ``commenced'' 
after August 7, 1977, is not BART-eligible.

         How are modifications treated under the BART provision?

    1. The NSPS program and the major source NSR program both contain 
the concept of modifications. In general, the term ``modification'' 
refers to any physical change or change in the method of operation of an 
emissions unit that results in an increase in emissions.
    2. The BART provision in the regional haze rule contains no explicit 
treatment of modifications or how modified emissions units, previously 
subject to the requirement to install best available control technology 
(BACT), lowest achievable emission rate (LAER) controls, and/or NSPS are 
treated under the rule. As the BART requirements in the CAA do not 
appear to provide any exemption for sources which have been modified 
since 1977, the best interpretation of the CAA visibility provisions is 
that a subsequent modification does not change a unit's construction 
date for the purpose of BART applicability. Accordingly, if an emissions 
unit began operation before 1962, it is not BART-eligible if it was 
modified between 1962 and 1977, so long as the modification is not also 
a ``reconstruction.'' On the other hand, an emissions unit which began 
operation within the 1962-1977 time window, but was modified after 
August 7, 1977, is BART-eligible. We note, however, that if such a 
modification was a major modification that resulted in the installation 
of controls, the State will take this into account during the review 
process and may find that the level of

[[Page 662]]

controls already in place are consistent with BART.

   3. Step 3: Compare the Potential Emissions to the 250 Ton/Yr Cutoff

    The result of Steps 1 and 2 will be a list of emissions units at a 
given plant site, including reconstructed emissions units, that are 
within one or more of the BART categories and that were placed into 
operation within the 1962-1977 time window. The third step is to 
determine whether the total emissions represent a current potential to 
emit that is greater than 250 tons per year of any single visibility 
impairing pollutant. Fugitive emissions, to the extent quantifiable, 
must be counted. In most cases, you will add the potential emissions 
from all emission units on the list resulting from Steps 1 and 2. In a 
few cases, you may need to determine whether the plant contains more 
than one ``stationary source'' as the regional haze rule defines that 
term, and as we explain further below.

                    What pollutants should I address?

    Visibility-impairing pollutants include the following:
    (1) Sulfur dioxide (SO2),
    (2) Nitrogen oxides (NOX), and
    (3) Particulate matter.
    You may use PM10 as an indicator for particulate matter 
in this intial step. [Note that we do not recommend use of total 
suspended particulates (TSP) as in indicator for particulate matter.] As 
emissions of PM10 include the components of PM2.5 
as a subset, there is no need to have separate 250 ton thresholds for 
PM10 and PM2.5; 250 tons of PM10 
represents at most 250 tons of PM2.5, and at most 250 tons of 
any individual particulate species such as elemental carbon, crustal 
material, etc.
    However, if you determine that a source of particulate matter is 
BART-eligible, it will be important to distinguish between the fine and 
coarse particle components of direct particulate emissions in the 
remainder of the BART analysis, including for the purpose of modeling 
the source's impact on visibility. This is because although both fine 
and coarse particulate matter contribute to visibility impairment, the 
long-range transport of fine particles is of particular concern in the 
formation of regional haze. Thus, for example, air quality modeling 
results used in the BART determination will provide a more accurate 
prediction of a source's impact on visibility if the inputs into the 
model account for the relative particle size of any directly emitted 
particulate matter (i.e. PM10 vs. PM2.5).
    You should exercise judgment in deciding whether the following 
pollutants impair visibility in an area:
    (4) Volatile organic compounds (VOC), and
    (5) Ammonia and ammonia compounds.
    You should use your best judgment in deciding whether VOC or ammonia 
emissions from a source are likely to have an impact on visibility in an 
area. Certain types of VOC emissions, for example, are more likely to 
form secondary organic aerosols than others. \1\ Similarly, controlling 
ammonia emissions in some areas may not have a significant impact on 
visibility. You need not provide a formal showing of an individual 
decision that a source of VOC or ammonia emissions is not subject to 
BART review. Because air quality modeling may not be feasible for 
individual sources of VOC or ammonia, you should also exercise your 
judgement in assessing the degree of visibility impacts due to emissions 
of VOC and emissions of ammonia or ammonia compounds. You should fully 
document the basis for judging that a VOC or ammonia source merits BART 
review, including your assessment of the source's contribution to 
visibility impairment.
---------------------------------------------------------------------------

    \1\ Fine particles: Overview of Atmospheric Chemistry, Sources of 
Emissions, and Ambient Monitoring Data, Memorandum to Docket OAR 2002-
006, April 1, 2005.
---------------------------------------------------------------------------

            What does the term ``potential'' emissions mean?

    The regional haze rule defines potential to emit as follows:

    ``Potential to emit'' means the maximum capacity of a stationary 
source to emit a pollutant under its physical and operational design. 
Any physical or operational limitation on the capacity of the source to 
emit a pollutant including air pollution control equipment and 
restrictions on hours of operation or on the type or amount of material 
combusted, stored, or processed, shall be treated as part of its design 
if the limitation or the effect it would have on emissions is federally 
enforceable. Secondary emissions do not count in determining the 
potential to emit of a stationary source.

The definition of ``potential to emit'' means that a source which 
actually emits less than 250 tons per year of a visibility-impairing 
pollutant is BART-eligible if its emissions would exceed 250 tons per 
year when operating at its maximum capacity given its physical and 
operational design (and considering all federally enforceable and State 
enforceable permit limits.)

    Example: A source, while operating at one-fourth of its capacity, 
emits 75 tons per year of SO2. If it were operating at 100 
percent of its maximum capacity, the source would emit 300 tons per 
year. Because under the above definition such a source would have 
``potential'' emissions that exceed 250 tons per year, the source (if in 
a listed category

[[Page 663]]

and built during the 1962-1977 time window) would be BART-eligible.

    How do I identify whether a plant has more than one ``stationary 
                                source?''

    1. The regional haze rule, in 40 CFR 51.301, defines a stationary 
source as a ``building, structure, facility or installation which emits 
or may emit any air pollutant.'' \2\ The rule further defines 
``building, structure or facility'' as:
---------------------------------------------------------------------------

    \2\ Note: Most of these terms and definitions are the same for 
regional haze and the 1980 visibility regulations. For the regional haze 
rule we use the term ``BART-eligible source'' rather than ``existing 
stationary facility'' to clarify that only a limited subset of existing 
stationary sources are subject to BART.

all of the pollutant-emitting activities which belong to the same 
industrial grouping, are located on one or more contiguous or adjacent 
properties, and are under the control of the same person (or persons 
under common control). Pollutant-emitting activities must be considered 
as part of the same industrial grouping if they belong to the same Major 
Group (i.e., which have the same two-digit code) as described in the 
Standard Industrial Classification Manual, 1972 as amended by the 1977 
Supplement (U.S. Government Printing Office stock numbers 4101-0066 and 
003-005-00176-0, respectively).

    2. In applying this definition, it is necessary to determine which 
facilities are located on ``contiguous or adjacent properties.'' Within 
this contiguous and adjacent area, it is also necessary to group those 
emission units that are under ``common control.'' We note that these 
plant boundary issues and ``common control'' issues are very similar to 
those already addressed in implementation of the title V operating 
permits program and in NSR.
    3. For emission units within the ``contiguous or adjacent'' boundary 
and under common control, you must group emission units that are within 
the same industrial grouping (that is, associated with the same 2-digit 
SIC code) in order to define the stationary source. \3\ For most plants 
on the BART source category list, there will only be one 2-digit SIC 
that applies to the entire plant. For example, all emission units 
associated with kraft pulp mills are within SIC code 26, and chemical 
process plants will generally include emission units that are all within 
SIC code 28. The ``2-digit SIC test'' applies in the same way as the 
test is applied in the major source NSR programs. \4\
---------------------------------------------------------------------------

    \3\ We recognize that we are in a transition period from the use of 
the SIC system to a new system called the North American Industry 
Classification System (NAICS). For purposes of identifying BART-eligible 
sources, you may use either 2-digit SICS or the equivalent in the NAICS 
system.
    \4\ Note: The concept of support facility used for the NSR program 
applies here as well. Support facilities, that is facilities that 
convey, store or otherwise assist in the production of the principal 
product, must be grouped with primary facilities even when the 
facilities fall wihin separate SIC codes. For purposes of BART reviews, 
however, such support facilities (a) must be within one of the 26 listed 
source categories and (b) must have been in existence as of August 7, 
1977, and (c) must not have been in operation as of August 7, 1962.
---------------------------------------------------------------------------

    4. For purposes of the regional haze rule, you must group emissions 
from all emission units put in place within the 1962-1977 time period 
that are within the 2-digit SIC code, even if those emission units are 
in different categories on the BART category list.

    Examples: A chemical plant which started operations within the 1962 
to 1977 time period manufactures hydrochloric acid (within the category 
title ``Hydrochloric, sulfuric, and nitric acid plants'') and various 
organic chemicals (within the category title ``chemical process 
plants''). All of the emission units are within SIC code 28 and, 
therefore, all the emission units are considered in determining BART 
eligibility of the plant. You sum the emissions over all of these 
emission units to see whether there are more than 250 tons per year of 
potential emissions.
    A steel mill which started operations within the 1962 to 1977 time 
period includes a sintering plant, a coke oven battery, and various 
other emission units. All of the emission units are within SIC code 33. 
You sum the emissions over all of these emission units to see whether 
there are more than 250 tons per year of potential emissions.

    4. Final Step: Identify the Emissions Units and Pollutants That 
                   Constitute the BART-Eligible Source

    If the emissions from the list of emissions units at a stationary 
source exceed a potential to emit of 250 tons per year for any 
visibility-impairing pollutant, then that collection of emissions units 
is a BART-eligible source.

    Example: A stationary source comprises the following two emissions 
units, with the following potential emissions:
Emissions unit A
200 tons/yr SO2
150 tons/yr NOX
25 tons/yr PM
Emissions unit B
100 tons/yr SO2
75 tons/yr NOX
10 tons/yr PM

For this example, potential emissions of SO2 are 300 tons/yr, 
which exceeds the 250 tons/yr

[[Page 664]]

threshold. Accordingly, the entire ``stationary source'', that is, 
emissions units A and B, may be subject to a BART review for 
SO2, NOX, and PM, even though the potential 
emissions of PM and NOX at each emissions unit are less than 
250 tons/yr each.
    Examples: The total potential emissions, obtained by adding the 
potential emissions of all emission units in a listed category at a 
plant site, are as follows:

200 tons/yr SO2
150 tons/yr NOX
25 tons/yr PM

    Even though total emissions exceed 250 tons/yr, no individual 
regulated pollutant exceeds 250 tons/yr and this source is not BART-
eligible.

 Can States establish de minimis levels of emissions for pollutants at 
                         BART-eligible sources?

    In order to simplify BART determinations, States may choose to 
identify de minimis levels of pollutants at BART-eligible sources (but 
are not required to do so). De minimis values should be identified with 
the purpose of excluding only those emissions so minimal that they are 
unlikely to contribute to regional haze. Any de minimis values that you 
adopt must not be higher than the PSD applicability levels: 40 tons/yr 
for SO2 and NOX and 15 tons/yr for 
PM10. These de minimis levels may only be applied on a plant-
wide basis.

            III. How To Identify Sources ``Subject to BART''

    Once you have compiled your list of BART-eligible sources, you need 
to determine whether (1) to make BART determinations for all of them or 
(2) to consider exempting some of them from BART because they may not 
reasonably be anticipated to cause or contribute to any visibility 
impairment in a Class I area. If you decide to make BART determinations 
for all the BART-eligible sources on your list, you should work with 
your regional planning organization (RPO) to show that, collectively, 
they cause or contribute to visibility impairment in at least one Class 
I area. You should then make individual BART determinations by applying 
the five statutory factors discussed in Section IV below.
    On the other hand, you also may choose to perform an initial 
examination to determine whether a particular BART-eligible source or 
group of sources causes or contributes to visibility impairment in 
nearby Class I areas. If your analysis, or information submitted by the 
source, shows that an individual source or group of sources (or certain 
pollutants from those sources) is not reasonably anticipated to cause or 
contribute to any visibility impairment in a Class I area, then you do 
not need to make BART determinations for that source or group of sources 
(or for certain pollutants from those sources). In such a case, the 
source is not ``subject to BART'' and you do not need to apply the five 
statutory factors to make a BART determination. This section of the 
Guideline discusses several approaches that you can use to exempt 
sources from the BART determination process.

  A. What Steps Do I Follow To Determine Whether a Source or Group of 
  Sources Cause or Contribute to Visibility Impairment for Purposes of 
                                  BART?

                   1. How Do I Establish a Threshold?

    One of the first steps in determining whether sources cause or 
contribute to visibility impairment for purposes of BART is to establish 
a threshold (measured in deciviews) against which to measure the 
visibility impact of one or more sources. A single source that is 
responsible for a 1.0 deciview change or more should be considered to 
``cause'' visibility impairment; a source that causes less than a 1.0 
deciview change may still contribute to visibility impairment and thus 
be subject to BART.
    Because of varying circumstances affecting different Class I areas, 
the appropriate threshold for determining whether a source ``contributes 
to any visibility impairment'' for the purposes of BART may reasonably 
differ across States. As a general matter, any threshold that you use 
for determining whether a source ``contributes'' to visibility 
impairment should not be higher than 0.5 deciviews.
    In setting a threshold for ``contribution,'' you should consider the 
number of emissions sources affecting the Class I areas at issue and the 
magnitude of the individual sources' impacts. \5\ In general, a larger 
number of sources causing impacts in a Class I area may warrant a lower 
contribution threshold. States remain free to use a threshold lower than 
0.5 deciviews if they conclude that the location of a large number of 
BART-eligible sources within the State and in proximity to a Class I 
area justify this approach. \6\
---------------------------------------------------------------------------

    \5\ We expect that regional planning organizations will have 
modeling information that identifies sources affecting visibility in 
individual class I areas.
    \6\ Note that the contribution threshold should be used to determine 
whether an individual source is reasonably anticipated to contribute to 
visibility impairment. You should not aggregate the visibility effects 
of multiple sources and compare their collective effects against your 
contribution threshold because this would inappropriately create a 
``contribute to contribution'' test.

---------------------------------------------------------------------------

[[Page 665]]

                2. What Pollutants Do I Need To Consider?

    You must look at SO2, NOX, and direct 
particulate matter (PM) emissions in determining whether sources cause 
or contribute to visibility impairment, including both PM10 
and PM2.5. Consistent with the approach for identifying your 
BART-eligible sources, you do not need to consider less than de minimis 
emissions of these pollutants from a source.
    As explained in section II, you must use your best judgement to 
determine whether VOC or ammonia emissions are likely to have an impact 
on visibility in an area. In addition, although as explained in Section 
II, you may use PM10 an indicator for particulate matter in 
determining whether a source is BART-eligible, in determining whether a 
source contributes to visibility impairment, you should distinguish 
between the fine and coarse particle components of direct particulate 
emissions. Although both fine and coarse particulate matter contribute 
to visibility impairment, the long-range transport of fine particles is 
of particular concern in the formation of regional haze. Air quality 
modeling results used in the BART determination will provide a more 
accurate prediction of a source's impact on visibility if the inputs 
into the model account for the relative particle size of any directly 
emitted particulate matter (i.e., PM10 vs. PM2.5).

  3. What Kind of Modeling Should I Use To Determine Which Sources and 
                 Pollutants Need Not Be Subject to BART?

    This section presents several options for determining that certain 
sources need not be subject to BART. These options rely on different 
modeling and/or emissions analysis approaches. They are provided for 
your guidance. You may also use other reasonable approaches for 
analyzing the visibility impacts of an individual source or group of 
sources.

 Option 1: Individual Source Attribution Approach (Dispersion Modeling)

    You can use dispersion modeling to determine that an individual 
source cannot reasonably be anticipated to cause or contribute to 
visibility impairment in a Class I area and thus is not subject to BART. 
Under this option, you can analyze an individual source's impact on 
visibility as a result of its emissions of SO2, 
NOX and direct PM emissions. Dispersion modeling cannot 
currently be used to estimate the predicted impacts on visibility from 
an individual source's emissions of VOC or ammonia. You may use a more 
qualitative assessment to determine on a case-by-case basis which 
sources of VOC or ammonia emissions may be likely to impair visibility 
and should therefore be subject to BART review, as explained in section 
II.A.3. above.
    You can use CALPUFF \7\ or other appropriate model to predict the 
visibility impacts from a single source at a Class I area. CALPUFF is 
the best regulatory modeling application currently available for 
predicting a single source's contribution to visibility impairment and 
is currently the only EPA-approved model for use in estimating single 
source pollutant concentrations resulting from the long range transport 
of primary pollutants. \8\ It can also be used for some other purposes, 
such as the visibility assessments addressed in today's rule, to account 
for the chemical transformation of SO2 and NOX.
---------------------------------------------------------------------------

    \7\ The model code and its documentation are available at no cost 
for download from http://www.epa.gov/scram001/tt22.htmcalpuff.
    \8\ The Guideline on Air Quality Models, 40 CFR part 51, appendix W, 
addresses the regulatory application of air quality models for assessing 
criteria pollutants under the CAA, and describes further the procedures 
for using the CALPUFF model, as well as for obtaining approval for the 
use of other, nonguideline models.
---------------------------------------------------------------------------

    There are several steps for making an individual source attribution 
using a dispersion model:
    1. Develop a modeling protocol. Some critical items to include in 
the protocol are the meteorological and terrain data that will be used, 
as well as the source-specific information (stack height, temperature, 
exit velocity, elevation, and emission rates of applicable pollutants) 
and receptor data from appropriate Class I areas. We recommend following 
EPA's Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 
Summary Report and Recommendations for Modeling Long Range Transport 
Impacts \9\ for parameter settings and meteorological data inputs. You 
may use other settings from those in IWAQM, but you should identify 
these settings and explain your selection of these settings.
---------------------------------------------------------------------------

    \9\ Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 
Summary Report and Recommendations for Modeling Long Range Transport 
Impacts, U.S. Environmental Protection Agency, EPA-454/R-98-019, 
December 1998.
---------------------------------------------------------------------------

    One important element of the protocol is in establishing the 
receptors that will be used in the model. The receptors that you use 
should be located in the nearest Class I area with sufficient density to 
identify the likely visibility effects of the source. For other Class I 
areas in relatively close proximity to a BART-eligible source, you may 
model a few strategic receptors to determine whether effects at those 
areas may be greater than at the nearest Class I area. For example, you 
might chose to locate receptors at these areas at the closest point to 
the

[[Page 666]]

source, at the highest and lowest elevation in the Class I area, at the 
IMPROVE monitor, and at the approximate expected plume release height. 
If the highest modeled effects are observed at the nearest Class I area, 
you may choose not to analyze the other Class I areas any further as 
additional analyses might be unwarranted.
    You should bear in mind that some receptors within the relevant 
Class I area may be less than 50 km from the source while other 
receptors within that same Class I area may be greater than 50 km from 
the same source. As indicated by the Guideline on Air Quality Models, 40 
CFR part 51, appendix W, this situation may call for the use of two 
different modeling approaches for the same Class I area and source, 
depending upon the State's chosen method for modeling sources less than 
50 km. In situations where you are assessing visibility impacts for 
source-receptor distances less than 50 km, you should use expert 
modeling judgment in determining visibility impacts, giving 
consideration to both CALPUFF and other appropriate methods.
    In developing your modeling protocol, you may want to consult with 
EPA and your regional planning organization (RPO). Up-front consultation 
will ensure that key technical issues are addressed before you conduct 
your modeling.
    2. With the accepted protocol and compare the predicted visibility 
impacts with your threshold for ``contribution.'' You should calculate 
daily visibility values for each receptor as the change in deciviews 
compared against natural visibility conditions. You can use EPA's 
``Guidance for Estimating Natural Visibility Conditions Under the 
Regional Haze Rule,'' EPA-454/B-03-005 (September 2003) in making this 
calculation. To determine whether a source may reasonably be anticipated 
to cause or contribute to visibility impairment at Class I area, you 
then compare the impacts predicted by the model against the threshold 
that you have selected.
    The emissions estimates used in the models are intended to reflect 
steady-state operating conditions during periods of high capacity 
utilization. We do not generally recommend that emissions reflecting 
periods of start-up, shutdown, and malfunction be used, as such emission 
rates could produce higher than normal effects than would be typical of 
most facilities. We recommend that States use the 24 hour average actual 
emission rate from the highest emitting day of the meteorological period 
modeled, unless this rate reflects periods start-up, shutdown, or 
malfunction. In addition, the monthly average relative humidity is used, 
rather than the daily average humidity--an approach that effectively 
lowers the peak values in daily model averages.
    For these reasons, if you use the modeling approach we recommend, 
you should compare your ``contribution'' threshold against the 98th 
percentile of values. If the 98th percentile value from your modeling is 
less than your contribution threshold, then you may conclude that the 
source does not contribute to visibility impairment and is not subject 
to BART.

 Option 2: Use of Model Plants To Exempt Individual Sources With Common 
                             Characteristics

    Under this option, analyses of model plants could be used to exempt 
certain BART-eligible sources that share specific characteristics. It 
may be most useful to use this type of analysis to identify the types of 
small sources that do not cause or contribute to visibility impairment 
for purposes of BART, and thus should not be subject to a BART review. 
Different Class I areas may have different characteristics, however, so 
you should use care to ensure that the criteria you develop are 
appropriate for the applicable cases.
    In carrying out this approach, you could use modeling analyses of 
representative plants to reflect groupings of specific sources with 
important common characteristics. Based on these analyses, you may find 
that certain types of sources are clearly anticipated to cause or 
contribute to visibility impairment. You could then choose to 
categorically require those types of sources to undergo a BART 
determination. Conversely, you may find based on representative plant 
analyses that certain types of sources are not reasonably anticipated to 
cause or contribute to visibility impairment. To do this, you may 
conduct your own modeling to establish emission levels and distances 
from Class I areas on which you can rely to exempt sources with those 
characteristics. For example, based on your modeling you might choose to 
exempt all NOX-only sources that emit less than a certain 
amount per year and are located a certain distance from a Class I area. 
You could then choose to categorically exempt such sources from the BART 
determination process.
    Our analyses of visibility impacts from model plants provide a 
useful example of the type of analyses that can be used to exempt 
categories of sources from BART. \10\ In our analyses, we developed 
model plants (EGUs and non-EGUs), with representative plume and stack 
characteristics, for use in considering the visibility impact from 
emission sources of different sizes and compositions at distances of 50, 
100 and 200 kilometers from two hypothetical Class I areas (one in the 
East and one in the West). As the plume and stack characteristics of 
these model plants were developed considering the broad range

[[Page 667]]

of sources within the EGU and non-EGU categories, they do not 
necessarily represent any specific plant. However, the results of these 
analyses are instructive in the development of an exemption process for 
any Class I area.
---------------------------------------------------------------------------

    \10\ CALPUFF Analysis in Support of the June 2005 Changes to the 
Regional Haze Rule, U.S. Environmental Protection Agency, June 15, 2005, 
Docket No. OAR-2002-0076.
---------------------------------------------------------------------------

    In preparing our analyses, we have made a number of assumptions and 
exercised certain modeling choices; some of these have a tendency to 
lend conservatism to the results, overstating the likely effects, while 
others may understate the likely effects. On balance, when all of these 
factors are considered, we believe that our examples reflect realistic 
treatments of the situations being modeled. Based on our analyses, we 
believe that a State that has established 0.5 deciviews as a 
contribution threshold could reasonably exempt from the BART review 
process sources that emit less than 500 tons per year of NOX 
or SO2 (or combined NOX and SO2), as 
long as these sources are located more than 50 kilometers from any Class 
I area; and sources that emit less than 1000 tons per year of 
NOX or SO2 (or combined NOX and 
SO2) that are located more than 100 kilometers from any Class 
I area. You do, however, have the option of showing other thresholds 
might also be appropriate given your specific circumstances.

  Option 3: Cumulative Modeling To Show That No Sources in a State Are 
                             Subject to BART

    You may also submit to EPA a demonstration based on an analysis of 
overall visibility impacts that emissions from BART-eligible sources in 
your State, considered together, are not reasonably anticipated to cause 
or contribute to any visibility impairment in a Class I area, and thus 
no source should be subject to BART. You may do this on a pollutant by 
pollutant basis or for all visibility-impairing pollutants to determine 
if emissions from these sources contribute to visibility impairment.
    For example, emissions of SO2 from your BART-eligible 
sources may clearly cause or contribute to visibility impairment while 
direct emissions of PM2.5 from these sources may not 
contribute to impairment. If you can make such a demonstration, then you 
may reasonably conclude that none of your BART-eligible sources are 
subject to BART for a particular pollutant or pollutants. As noted 
above, your demonstration should take into account the interactions 
among pollutants and their resulting impacts on visibility before making 
any pollutant-specific determinations.
    Analyses may be conducted using several alternative modeling 
approaches. First, you may use the CALPUFF or other appropriate model as 
described in Option 1 to evaluate the impacts of individual sources on 
downwind Class I areas, aggregating those impacts to determine the 
collective contribution of all BART-eligible sources to visibility 
impairment. You may also use a photochemical grid model. As a general 
matter, the larger the number of sources being modeled, the more 
appropriate it may be to use a photochemical grid model. However, 
because such models are significantly less sensitive than dispersion 
models to the contributions of one or a few sources, as well as to the 
interactions among sources that are widely distributed geographically, 
if you wish to use a grid model, you should consult with the appropriate 
EPA Regional Office to develop an appropriate modeling protocol.

          IV. The BART Determination: Analysis of BART Options

    This section describes the process for the analysis of control 
options for sources subject to BART.

           A. What factors must I address in the BART review?

    The visibility regulations define BART as follows:
    Best Available Retrofit Technology (BART) means an emission 
limitation based on the degree of reduction achievable through the 
application of the best system of continuous emission reduction for each 
pollutant which is emitted by . . . [a BART-eligible source]. The 
emission limitation must be established, on a case-by-case basis, taking 
into consideration the technology available, the costs of compliance, 
the energy and non-air quality environmental impacts of compliance, any 
pollution control equipment in use or in existence at the source, the 
remaining useful life of the source, and the degree of improvement in 
visibility which may reasonably be anticipated to result from the use of 
such technology.
    The BART analysis identifies the best system of continuous emission 
reduction taking into account:
    (1) The available retrofit control options,
    (2) Any pollution control equipment in use at the source (which 
affects the availability of options and their impacts),
    (3) The costs of compliance with control options,
    (4) The remaining useful life of the facility,
    (5) The energy and non-air quality environmental impacts of control 
options
    (6) The visibility impacts analysis.

                B. What is the scope of the BART review?

    Once you determine that a source is subject to BART for a particular 
pollutant, then for each affected emission unit, you must establish BART 
for that pollutant. The BART determination must address air pollution 
control measures for each emissions unit or pollutant emitting activity 
subject to review.

    Example: Plantwide emissions from emission units within the listed 
categories that

[[Page 668]]

began operation within the ``time window'' for BART \11\ are 300 tons/yr 
of NOX, 200 tons/yr of SO2, and 150 tons/yr of 
primary particulate. Emissions unit A emits 200 tons/yr of 
NOX, 100 tons/yr of SO2, and 100 tons/yr of 
primary particulate. Other emission units, units B through H, which 
began operating in 1966, contribute lesser amounts of each pollutant. 
For this example, a BART review is required for NOX, 
SO2, and primary particulate, and control options must be 
analyzed for units B through H as well as unit A.
---------------------------------------------------------------------------

    \11\ That is, emission units that were in existence on August 7, 
1977 and which began actual operation on or after August 7, 1962.
---------------------------------------------------------------------------

     C. How does a BART review relate to Maximum Achievable Control 
Technology (MACT) Standards under CAA section 112, or to other emission 
                   limitations required under the CAA?

    For VOC and PM sources subject to MACT standards, States may 
streamline the analysis by including a discussion of the MACT controls 
and whether any major new technologies have been developed subsequent to 
the MACT standards. We believe that there are many VOC and PM sources 
that are well controlled because they are regulated by the MACT 
standards, which EPA developed under CAA section 112. For a few MACT 
standards, this may also be true for SO2. Any source subject 
to MACT standards must meet a level that is as stringent as the best-
controlled 12 percent of sources in the industry. Examples of these 
hazardous air pollutant sources which effectively control VOC and PM 
emissions include (among others) secondary lead facilities, organic 
chemical plants subject to the hazardous organic NESHAP (HON), 
pharmaceutical production facilities, and equipment leaks and wastewater 
operations at petroleum refineries. We believe that, in many cases, it 
will be unlikely that States will identify emission controls more 
stringent than the MACT standards without identifying control options 
that would cost many thousands of dollars per ton. Unless there are new 
technologies subsequent to the MACT standards which would lead to cost-
effective increases in the level of control, you may rely on the MACT 
standards for purposes of BART.
    We believe that the same rationale also holds true for emissions 
standards developed for municipal waste incinerators under CAA section 
111(d), and for many NSR/PSD determinations and NSR/PSD settlement 
agreements. However, we do not believe that technology determinations 
from the 1970s or early 1980s, including new source performance 
standards (NSPS), should be considered to represent best control for 
existing sources, as best control levels for recent plant retrofits are 
more stringent than these older levels.
    Where you are relying on these standards to represent a BART level 
of control, you should provide the public with a discussion of whether 
any new technologies have subsequently become available.

    D. What Are the Five Basic Steps of a Case-by-Case BART Analysis?

    The five steps are:
    STEP 1--Identify All \12\ Available Retrofit Control Technologies,
---------------------------------------------------------------------------

    \12\ In identifying ``all'' options, you must identify the most 
stringent option and a reasonable set of options for analysis that 
reflects a comprehensive list of available technologies. It is not 
necessary to list all permutations of available control levels that 
exist for a given technology--the list is complete if it includes the 
maximum level of control each technology is capable of achieving.
---------------------------------------------------------------------------

    STEP 2--Eliminate Technically Infeasible Options,
    STEP 3--Evaluate Control Effectiveness of Remaining Control 
Technologies,
    STEP 4--Evaluate Impacts and Document the Results, and
    STEP 5--Evaluate Visibility Impacts.

  1. STEP 1: How do I identify all available retrofit emission control 
                               techniques?

    1. Available retrofit control options are those air pollution 
control technologies with a practical potential for application to the 
emissions unit and the regulated pollutant under evaluation. Air 
pollution control technologies can include a wide variety of available 
methods, systems, and techniques for control of the affected pollutant. 
Technologies required as BACT or LAER are available for BART purposes 
and must be included as control alternatives. The control alternatives 
can include not only existing controls for the source category in 
question but also take into account technology transfer of controls that 
have been applied to similar source categories and gas streams. 
Technologies which have not yet been applied to (or permitted for) full 
scale operations need not be considered as available; we do not expect 
the source owner to purchase or construct a process or control device 
that has not already been demonstrated in practice.
    2. Where a NSPS exists for a source category (which is the case for 
most of the categories affected by BART), you should include a level of 
control equivalent to the NSPS as one of the control options. \13\ The

[[Page 669]]

NSPS standards are codified in 40 CFR part 60. We note that there are 
situations where NSPS standards do not require the most stringent level 
of available control for all sources within a category. For example, 
post-combustion NOX controls (the most stringent controls for 
stationary gas turbines) are not required under subpart GG of the NSPS 
for Stationary Gas Turbines. However, such controls must still be 
considered available technologies for the BART selection process.
---------------------------------------------------------------------------

    \13\ In EPA's 1980 BART guidelines for reasonably attributable 
visibility impairment, we concluded that NSPS standards generally, at 
that time, represented the best level sources could install as BART. In 
the 20 year period since this guidance was developed, there have been 
advances in SO2 control technologies as well as technologies 
for the control of other pollutants, confirmed by a number of recent 
retrofits at Western power plants. Accordingly, EPA no longer concludes 
that the NSPS level of controls automatically represents ``the best 
these sources can install.'' Analysis of the BART factors could result 
in the selection of a NSPS level of control, but you should reach this 
conclusion only after considering the full range of control options.
---------------------------------------------------------------------------

    3. Potentially applicable retrofit control alternatives can be 
categorized in three ways.
     Pollution prevention: use of inherently lower-
emitting processes/practices, including the use of control techniques 
(e.g., low-NOX burners) and work practices that prevent 
emissions and result in lower ``production-specific'' emissions (note 
that it is not our intent to direct States to switch fuel forms, e.g., 
from coal to gas),
     Use of (and where already in place, improvement 
in the performance of) add-on controls, such as scrubbers, fabric 
filters, thermal oxidizers and other devices that control and reduce 
emissions after they are produced, and
     Combinations of inherently lower-emitting 
processes and add-on controls.
    4. In the course of the BART review, one or more of the available 
control options may be eliminated from consideration because they are 
demonstrated to be technically infeasible or to have unacceptable 
energy, cost, or non-air quality environmental impacts on a case-by-case 
(or site-specific) basis. However, at the outset, you should initially 
identify all control options with potential application to the emissions 
unit under review.
    5. We do not consider BART as a requirement to redesign the source 
when considering available control alternatives. For example, where the 
source subject to BART is a coal-fired electric generator, we do not 
require the BART analysis to consider building a natural gas-fired 
electric turbine although the turbine may be inherently less polluting 
on a per unit basis.
    6. For emission units subject to a BART review, there will often be 
control measures or devices already in place. For such emission units, 
it is important to include control options that involve improvements to 
existing controls and not to limit the control options only to those 
measures that involve a complete replacement of control devices.

    Example: For a power plant with an existing wet scrubber, the 
current control efficiency is 66 percent. Part of the reason for the 
relatively low control efficiency is that 22 percent of the gas stream 
bypasses the scrubber. A BART review identifies options for improving 
the performance of the wet scrubber by redesigning the internal 
components of the scrubber and by eliminating or reducing the percentage 
of the gas stream that bypasses the scrubber. Four control options are 
identified: (1) 78 percent control based upon improved scrubber 
performance while maintaining the 22 percent bypass, (2) 83 percent 
control based upon improved scrubber performance while reducing the 
bypass to 15 percent, (3) 93 percent control based upon improving the 
scrubber performance while eliminating the bypass entirely, (this option 
results in a ``wet stack'' operation in which the gas leaving the stack 
is saturated with water) and (4) 93 percent as in option 3, with the 
addition of an indirect reheat system to reheat the stack gas above the 
saturation temperature. You must consider each of these four options in 
a BART analysis for this source.

    7. You are expected to identify potentially applicable retrofit 
control technologies that represent the full range of demonstrated 
alternatives. Examples of general information sources to consider 
include:
     The EPA's Clean Air Technology Center, which 
includes the RACT/BACT/LAER Clearinghouse (RBLC);
     State and Local Best Available Control Technology 
Guidelines--many agencies have online information--for example South 
Coast Air Quality Management District, Bay Area Air Quality Management 
District, and Texas Natural Resources Conservation Commission;
     Control technology vendors;
     Federal/State/Local NSR permits and associated 
inspection/performance test reports;
     Environmental consultants;
     Technical journals, reports and newsletters, air 
pollution control seminars; and
     The EPA's NSR bulletin board--http://www.epa.gov/
ttn/nsr;
     Department of Energy's Clean Coal Program--
technical reports;
     The NOX Control Technology ``Cost 
Tool''--Clean Air Markets Division Web page--http://www.epa.gov/
airmarkets/arp/nox/controltech.html;
     Performance of selective catalytic reduction on 
coal-fired steam generating units--

[[Page 670]]

final report. OAR/ARD, June 1997 (also available at http://www.epa.gov/
airmarkets/arp/nox/controltech.html);
     Cost estimates for selected applications of 
NOX control technologies on stationary combustion boilers. 
OAR/ARD June 1997. (Docket for NOX SIP Call, A-96-56, item 
II-A-03);
     Investigation of performance and cost of 
NOX controls as applied to group 2 boilers. OAR/ARD, August 
1996. (Docket for Phase II NOX rule, A-95-28, item IV-A-4);
     Controlling SO2 Emissions: A Review of 
Technologies. EPA-600/R-00-093, USEPA/ORD/NRMRL, October 2000; and
     The OAQPS Control Cost Manual.
    You are expected to compile appropriate information from these 
information sources.
    8. There may be situations where a specific set of units within a 
fenceline constitutes the logical set to which controls would apply and 
that set of units may or may not all be BART-eligible. (For example, 
some units in that set may not have been constructed between 1962 and 
1977.)
    9. If you find that a BART source has controls already in place 
which are the most stringent controls available (note that this means 
that all possible improvements to any control devices have been made), 
then it is not necessary to comprehensively complete each following step 
of the BART analysis in this section. As long these most stringent 
controls available are made federally enforceable for the purpose of 
implementing BART for that source, you may skip the remaining analyses 
in this section, including the visibility analysis in step 5. Likewise, 
if a source commits to a BART determination that consists of the most 
stringent controls available, then there is no need to complete the 
remaining analyses in this section.

 2. STEP 2: How do I determine whether the options identified in Step 1 
                        are technically feasible?

    In Step 2, you evaluate the technical feasibility of the control 
options you identified in Step 1. You should document a demonstration of 
technical infeasibility and should explain, based on physical, chemical, 
or engineering principles, why technical difficulties would preclude the 
successful use of the control option on the emissions unit under review. 
You may then eliminate such technically infeasible control options from 
further consideration in the BART analysis.

          In general, what do we mean by technical feasibility?

    Control technologies are technically feasible if either (1) they 
have been installed and operated successfully for the type of source 
under review under similar conditions, or (2) the technology could be 
applied to the source under review. Two key concepts are important in 
determining whether a technology could be applied: ``availability'' and 
``applicability.'' As explained in more detail below, a technology is 
considered ``available'' if the source owner may obtain it through 
commercial channels, or it is otherwise available within the common 
sense meaning of the term. An available technology is ``applicable'' if 
it can reasonably be installed and operated on the source type under 
consideration. A technology that is available and applicable is 
technically feasible.

              What do we mean by ``available'' technology?

    1. The typical stages for bringing a control technology concept to 
reality as a commercial product are:
     Concept stage;
     Research and patenting;
     Bench scale or laboratory testing;
     Pilot scale testing;
     Licensing and commercial demonstration; and
     Commercial sales.
    2. A control technique is considered available, within the context 
presented above, if it has reached the stage of licensing and commercial 
availability. Similarly, we do not expect a source owner to conduct 
extended trials to learn how to apply a technology on a totally new and 
dissimilar source type. Consequently, you would not consider 
technologies in the pilot scale testing stages of development as 
``available'' for purposes of BART review.
    3. Commercial availability by itself, however, is not necessarily a 
sufficient basis for concluding a technology to be applicable and 
therefore technically feasible. Technical feasibility, as determined in 
Step 2, also means a control option may reasonably be deployed on or 
``applicable'' to the source type under consideration.
    Because a new technology may become available at various points in 
time during the BART analysis process, we believe that guidelines are 
needed on when a technology must be considered. For example, a 
technology may become available during the public comment period on the 
State's rule development process. Likewise, it is possible that new 
technologies may become available after the close of the State's public 
comment period and before submittal of the SIP to EPA, or during EPA's 
review process on the SIP submittal. In order to provide certainty in 
the process, all technologies should be considered if available before 
the close of the State's public comment period. You need not consider 
technologies that become available after this date. As part of your 
analysis, you should consider any technologies brought to your attention 
in public comments. If you disagree with public comments asserting that 
the technology is available, you should

[[Page 671]]

provide an explanation for the public record as to the basis for your 
conclusion.

              What do we mean by ``applicable'' technology?

    You need to exercise technical judgment in determining whether a 
control alternative is applicable to the source type under 
consideration. In general, a commercially available control option will 
be presumed applicable if it has been used on the same or a similar 
source type. Absent a showing of this type, you evaluate technical 
feasibility by examining the physical and chemical characteristics of 
the pollutant-bearing gas stream, and comparing them to the gas stream 
characteristics of the source types to which the technology had been 
applied previously. Deployment of the control technology on a new or 
existing source with similar gas stream characteristics is generally a 
sufficient basis for concluding the technology is technically feasible 
barring a demonstration to the contrary as described below.

 What type of demonstration is required if I conclude that an option is 
                        not technically feasible?

    1. Where you conclude that a control option identified in Step 1 is 
technically infeasible, you should demonstrate that the option is either 
commercially unavailable, or that specific circumstances preclude its 
application to a particular emission unit. Generally, such a 
demonstration involves an evaluation of the characteristics of the 
pollutant-bearing gas stream and the capabilities of the technology. 
Alternatively, a demonstration of technical infeasibility may involve a 
showing that there are unresolvable technical difficulties with applying 
the control to the source (e.g., size of the unit, location of the 
proposed site, operating problems related to specific circumstances of 
the source, space constraints, reliability, and adverse side effects on 
the rest of the facility). Where the resolution of technical 
difficulties is merely a matter of increased cost, you should consider 
the technology to be technically feasible. The cost of a control 
alternative is considered later in the process.
    2. The determination of technical feasibility is sometimes 
influenced by recent air quality permits. In some cases, an air quality 
permit may require a certain level of control, but the level of control 
in a permit is not expected to be achieved in practice (e.g., a source 
has received a permit but the project was canceled, or every operating 
source at that permitted level has been physically unable to achieve 
compliance with the limit). Where this is the case, you should provide 
supporting documentation showing why such limits are not technically 
feasible, and, therefore, why the level of control (but not necessarily 
the technology) may be eliminated from further consideration. However, 
if there is a permit requiring the application of a certain technology 
or emission limit to be achieved for such technology, this usually is 
sufficient justification for you to assume the technical feasibility of 
that technology or emission limit.
    3. Physical modifications needed to resolve technical obstacles do 
not, in and of themselves, provide a justification for eliminating the 
control technique on the basis of technical infeasibility. However, you 
may consider the cost of such modifications in estimating costs. This, 
in turn, may form the basis for eliminating a control technology (see 
later discussion).
    4. Vendor guarantees may provide an indication of commercial 
availability and the technical feasibility of a control technique and 
could contribute to a determination of technical feasibility or 
technical infeasibility, depending on circumstances. However, we do not 
consider a vendor guarantee alone to be sufficient justification that a 
control option will work. Conversely, lack of a vendor guarantee by 
itself does not present sufficient justification that a control option 
or an emissions limit is technically infeasible. Generally, you should 
make decisions about technical feasibility based on chemical, and 
engineering analyses (as discussed above), in conjunction with 
information about vendor guarantees.
    5. A possible outcome of the BART procedures discussed in these 
guidelines is the evaluation of multiple control technology alternatives 
which result in essentially equivalent emissions. It is not our intent 
to encourage evaluation of unnecessarily large numbers of control 
alternatives for every emissions unit. Consequently, you should use 
judgment in deciding on those alternatives for which you will conduct 
the detailed impacts analysis (Step 4 below). For example, if two or 
more control techniques result in control levels that are essentially 
identical, considering the uncertainties of emissions factors and other 
parameters pertinent to estimating performance, you may evaluate only 
the less costly of these options. You should narrow the scope of the 
BART analysis in this way only if there is a negligible difference in 
emissions and energy and non-air quality environmental impacts between 
control alternatives.

     3. STEP 3: How do I evaluate technically feasible alternatives?

    Step 3 involves evaluating the control effectiveness of all the 
technically feasible control alternatives identified in Step 2 for the 
pollutant and emissions unit under review.
    Two key issues in this process include:
    (1) Making sure that you express the degree of control using a 
metric that ensures

[[Page 672]]

an ``apples to apples'' comparison of emissions performance levels among 
options, and
    (2) Giving appropriate treatment and consideration of control 
techniques that can operate over a wide range of emission performance 
levels.

            What are the appropriate metrics for comparison?

    This issue is especially important when you compare inherently 
lower-polluting processes to one another or to add-on controls. In such 
cases, it is generally most effective to express emissions performance 
as an average steady state emissions level per unit of product produced 
or processed.
    Examples of common metrics:
     Pounds of SO2 emissions per million 
Btu heat input, and
     Pounds of NOX emissions per ton of 
cement produced.

   How do I evaluate control techniques with a wide range of emission 
                           performance levels?

    1. Many control techniques, including both add-on controls and 
inherently lower polluting processes, can perform at a wide range of 
levels. Scrubbers and high and low efficiency electrostatic 
precipitators (ESPs) are two of the many examples of such control 
techniques that can perform at a wide range of levels. It is not our 
intent to require analysis of each possible level of efficiency for a 
control technique as such an analysis would result in a large number of 
options. It is important, however, that in analyzing the technology you 
take into account the most stringent emission control level that the 
technology is capable of achieving. You should consider recent 
regulatory decisions and performance data (e.g., manufacturer's data, 
engineering estimates and the experience of other sources) when 
identifying an emissions performance level or levels to evaluate.
    2. In assessing the capability of the control alternative, latitude 
exists to consider special circumstances pertinent to the specific 
source under review, or regarding the prior application of the control 
alternative. However, you should explain the basis for choosing the 
alternate level (or range) of control in the BART analysis. Without a 
showing of differences between the source and other sources that have 
achieved more stringent emissions limits, you should conclude that the 
level being achieved by those other sources is representative of the 
achievable level for the source being analyzed.
    3. You may encounter cases where you may wish to evaluate other 
levels of control in addition to the most stringent level for a given 
device. While you must consider the most stringent level as one of the 
control options, you may consider less stringent levels of control as 
additional options. This would be useful, particularly in cases where 
the selection of additional options would have widely varying costs and 
other impacts.
    4. Finally, we note that for retrofitting existing sources in 
addressing BART, you should consider ways to improve the performance of 
existing control devices, particularly when a control device is not 
achieving the level of control that other similar sources are achieving 
in practice with the same device. For example, you should consider 
requiring those sources with electrostatic precipitators (ESPs) 
performing below currently achievable levels to improve their 
performance.

 4. STEP 4: For a BART review, what impacts am I expected to calculate 
  and report? What methods does EPA recommend for the impacts analysis?

    After you identify the available and technically feasible control 
technology options, you are expected to conduct the following analyses 
when you make a BART determination:

    Impact analysis part 1: Costs of compliance,
    Impact analysis part 2: Energy impacts, and
    Impact analysis part 3: Non-air quality environmental impacts.
    Impact analysis part 4: Remaining useful life.

In this section, we describe how to conduct each of these three 
analyses. You are responsible for presenting an evaluation of each 
impact along with appropriate supporting information. You should discuss 
and, where possible, quantify both beneficial and adverse impacts. In 
general, the analysis should focus on the direct impact of the control 
alternative.

   a. Impact analysis part 1: how do I estimate the costs of control?

    1. To conduct a cost analysis, you:
    (1) Identify the emissions units being controlled,
    (2) Identify design parameters for emission controls, and
    (3) Develop cost estimates based upon those design parameters.
    2. It is important to identify clearly the emission units being 
controlled, that is, to specify a well-defined area or process segment 
within the plant. In some cases, multiple emission units can be 
controlled jointly. However, in other cases, it may be appropriate in 
the cost analysis to consider whether multiple units will be required to 
install separate and/or different control devices. The analysis should 
provide a clear summary list of equipment and the associated control 
costs. Inadequate documentation of the equipment whose emissions are 
being controlled is a potential cause for confusion in

[[Page 673]]

comparison of costs of the same controls applied to similar sources.
    3. You then specify the control system design parameters. Potential 
sources of these design parameters include equipment vendors, background 
information documents used to support NSPS development, control 
technique guidelines documents, cost manuals developed by EPA, control 
data in trade publications, and engineering and performance test data. 
The following are a few examples of design parameters for two example 
control measures:

------------------------------------------------------------------------
            Control device                Examples of design parameters
------------------------------------------------------------------------
Wet Scrubbers.........................  Type of sorbent used (lime,
                                         limestone, etc.).
                                        Gas pressure drop.
                                        Liquid/gas ratio.
Selective Catalytic Reduction.........  Ammonia to NOX molar ratio.
                                        Pressure drop.
                                        Catalyst life.
------------------------------------------------------------------------

    4. The value selected for the design parameter should ensure that 
the control option will achieve the level of emission control being 
evaluated. You should include in your analysis documentation of your 
assumptions regarding design parameters. Examples of supporting 
references would include the EPA OAQPS Control Cost Manual (see below) 
and background information documents used for NSPS and hazardous 
pollutant emission standards. If the design parameters you specified 
differ from typical designs, you should document the difference by 
supplying performance test data for the control technology in question 
applied to the same source or a similar source.
    5. Once the control technology alternatives and achievable emissions 
performance levels have been identified, you then develop estimates of 
capital and annual costs. The basis for equipment cost estimates also 
should be documented, either with data supplied by an equipment vendor 
(i.e., budget estimates or bids) or by a referenced source (such as the 
OAQPS Control Cost Manual, Fifth Edition, February 1996, EPA 453/B-96-
001). \14\ In order to maintain and improve consistency, cost estimates 
should be based on the OAQPS Control Cost Manual, where possible. \15\ 
The Control Cost Manual addresses most control technologies in 
sufficient detail for a BART analysis. The cost analysis should also 
take into account any site-specific design or other conditions 
identified above that affect the cost of a particular BART technology 
option.
---------------------------------------------------------------------------

    \14\ The OAQPS Control Cost Manual is updated periodically. While 
this citation refers to the latest version at the time this guidance was 
written, you should use the version that is current as of when you 
conduct your impact analysis. This document is available at the 
following Web site: http://www.epa.gov/ttn/catc/dir1/cs1ch2.pdf.
    \15\ You should include documentation for any additional information 
you used for the cost calculations, including any information supplied 
by vendors that affects your assumptions regarding purchased equipment 
costs, equipment life, replacement of major components, and any other 
element of the calculation that differs from the Control Cost Manual.
---------------------------------------------------------------------------

                b. What do we mean by cost effectiveness?

    Cost effectiveness, in general, is a criterion used to assess the 
potential for achieving an objective in the most economical way. For 
purposes of air pollutant analysis, ``effectiveness'' is measured in 
terms of tons of pollutant emissions removed, and ``cost'' is measured 
in terms of annualized control costs. We recommend two types of cost-
effectiveness calculations--average cost effectiveness, and incremental 
cost effectiveness.

            c. How do I calculate average cost effectiveness?

    Average cost effectiveness means the total annualized costs of 
control divided by annual emissions reductions (the difference between 
baseline annual emissions and the estimate of emissions after controls), 
using the following formula:

Average cost effectiveness (dollars per ton removed) =Control option 
          annualized cost \16\
---------------------------------------------------------------------------

    \16\ Whenever you calculate or report annual costs, you should 
indicate the year for which the costs are estimated. For example, if you 
use the year 2000 as the basis for cost comparisons, you would report 
that an annualized cost of $20 million would be: $20 million (year 2000 
dollars).

Baseline annual emissions--Annual emissions with Control option
    Because you calculate costs in (annualized) dollars per year ($/yr) 
and because you calculate emissions rates in tons per year (tons/yr), 
the result is an average cost-effectiveness number in (annualized) 
dollars per ton ($/ton) of pollutant removed.

                d. How do I calculate baseline emissions?

    1. The baseline emissions rate should represent a realistic 
depiction of anticipated annual emissions for the source. In general, 
for the existing sources subject to BART, you will estimate the 
anticipated annual emissions based upon actual emissions from a baseline 
period.
    2. When you project that future operating parameters (e.g., limited 
hours of operation or capacity utilization, type of fuel, raw materials 
or product mix or type) will differ from past practice, and if this 
projection has a deciding effect in the BART determination,

[[Page 674]]

then you must make these parameters or assumptions into enforceable 
limitations. In the absence of enforceable limitations, you calculate 
baseline emissions based upon continuation of past practice.
    3. For example, the baseline emissions calculation for an emergency 
standby generator may consider the fact that the source owner would not 
operate more than past practice of 2 weeks a year. On the other hand, 
baseline emissions associated with a base-loaded turbine should be based 
on its past practice which would indicate a large number of hours of 
operation. This produces a significantly higher level of baseline 
emissions than in the case of the emergency/standby unit and results in 
more cost-effective controls. As a consequence of the dissimilar 
baseline emissions, BART for the two cases could be very different.

          e. How do I calculate incremental cost effectiveness?

    1. In addition to the average cost effectiveness of a control 
option, you should also calculate incremental cost effectiveness. You 
should consider the incremental cost effectiveness in combination with 
the average cost effectiveness when considering whether to eliminate a 
control option. The incremental cost effectiveness calculation compares 
the costs and performance level of a control option to those of the next 
most stringent option, as shown in the following formula (with respect 
to cost per emissions reduction):

Incremental Cost Effectiveness (dollars per incremental ton removed) = 
          (Total annualized costs of control option) - (Total annualized 
          costs of next control option) / (Control option annual 
          emissions) - (Next control option annual emissions)

    Example 1: Assume that Option F on Figure 2 has total annualized 
costs of $1 million to reduce 2000 tons of a pollutant, and that Option 
D on Figure 2 has total annualized costs of $500,000 to reduce 1000 tons 
of the same pollutant. The incremental cost effectiveness of Option F 
relative to Option D is ($1 million - $500,000) divided by (2000 tons - 
1000 tons), or $500,000 divided by 1000 tons, which is $500/ton.
    Example 2: Assume that two control options exist: Option 1 and 
Option 2. Option 1 achieves a 1,000 ton/yr reduction at an annualized 
cost of $1,900,000. This represents an average cost of ($1,900,000/1,000 
tons) = $1,900/ton. Option 2 achieves a 980 tons/yr reduction at an 
annualized cost of $1,500,000. This represents an average cost of 
($1,500,000/980 tons) = $1,531/ton. The incremental cost effectiveness 
of Option 1 relative to Option 2 is ($1,900,000 - $1,500,000) divided by 
(1,000 tons - 980 tons). The adoption of Option 1 instead of Option 2 
results in an incremental emission reduction of 20 tons per year at an 
additional cost of $400,000 per year. The incremental cost of Option 1, 
then, is $20,000 per ton - 11 times the average cost of $1,900 per ton. 
While $1,900 per ton may still be deemed reasonable, it is useful to 
consider both the average and incremental cost in making an overall 
cost-effectiveness finding. Of course, there may be other differences 
between these options, such as, energy or water use, or non-air 
environmental effects, which also should be considered in selecting a 
BART technology.

    2. You should exercise care in deriving incremental costs of 
candidate control options. Incremental cost-effectiveness comparisons 
should focus on annualized cost and emission reduction differences 
between ``dominant'' alternatives. To identify dominant alternatives, 
you generate a graphical plot of total annualized costs for total 
emissions reductions for all control alternatives identified in the BART 
analysis, and by identifying a ``least-cost envelope'' as shown in 
Figure 2. (A ``least-cost envelope'' represents the set of options that 
should be dominant in the choice of a specific option.)

[[Page 675]]

[GRAPHIC] [TIFF OMITTED] TR06JY05.000

    Example: Eight technically feasible control options for analysis are 
listed. These are represented as A through H in Figure 2. The dominant 
set of control options, B, D, F, G, and H, represent the least-cost 
envelope, as we depict by the cost curve connecting them. Points A, C 
and E are inferior options, and you should not use them in calculating 
incremental cost effectiveness. Points A, C and E represent inferior 
controls because B will buy more emissions reductions for less money 
than A; and similarly, D and F will buy more reductions for less money 
than C and E, respectively.

    3. In calculating incremental costs, you:
    (1) Array the control options in ascending order of annualized total 
costs,
    (2) Develop a graph of the most reasonable smooth curve of the 
control options, as shown in Figure 2. This is to show the ``least-cost 
envelope'' discussed above; and
    (3) Calculate the incremental cost effectiveness for each dominant 
option, which is the difference in total annual costs between that 
option and the next most stringent option, divided by the difference in 
emissions, after controls have been applied, between those two control 
options. For example, using Figure 2, you would calculate incremental 
cost effectiveness for the difference between options B and D, options D 
and F, options F and G, and options G and H.
    4. A comparison of incremental costs can also be useful in 
evaluating the viability of a specific control option over a range of 
efficiencies. For example, depending on the capital and operational cost 
of a control device, total and incremental cost may vary significantly 
(either increasing or decreasing) over the operational range of a 
control device. Also, the greater the number of possible control options 
that exist, the more weight should be given to the incremental costs vs. 
average costs. It should be noted that average and incremental cost 
effectiveness are identical when only one candidate control option is 
known to exist.
    5. You should exercise caution not to misuse these techniques. For 
example, you may be faced with a choice between two available control 
devices at a source, control A and control B, where control B achieves 
slightly

[[Page 676]]

greater emission reductions. The average cost (total annual cost/total 
annual emission reductions) for each may be deemed to be reasonable. 
However, the incremental cost (total annual costA - B/total 
annual emission reductionsA - B) of the additional emission 
reductions to be achieved by control B may be very great. In such an 
instance, it may be inappropriate to choose control B, based on its high 
incremental costs, even though its average cost may be considered 
reasonable.
    6. In addition, when you evaluate the average or incremental cost 
effectiveness of a control alternative, you should make reasonable and 
supportable assumptions regarding control efficiencies. An 
unrealistically low assessment of the emission reduction potential of a 
certain technology could result in inflated cost-effectiveness figures.

f. What other information should I provide in the cost impacts analysis?

    You should provide documentation of any unusual circumstances that 
exist for the source that would lead to cost-effectiveness estimates 
that would exceed that for recent retrofits. This is especially 
important in cases where recent retrofits have cost-effectiveness values 
that are within what has been considered a reasonable range, but your 
analysis concludes that costs for the source being analyzed are not 
considered reasonable. (A reasonable range would be a range that is 
consistent with the range of cost effectiveness values used in other 
similar permit decisions over a period of time.)

    Example: In an arid region, large amounts of water are needed for a 
scrubbing system. Acquiring water from a distant location could greatly 
increase the cost per ton of emissions reduced of wet scrubbing as a 
control option.

   g. What other things are important to consider in the cost impacts 
                                analysis?

    In the cost analysis, you should take care not to focus on 
incomplete results or partial calculations. For example, large capital 
costs for a control option alone would not preclude selection of a 
control measure if large emissions reductions are projected. In such a 
case, low or reasonable cost effectiveness numbers may validate the 
option as an appropriate BART alternative irrespective of the large 
capital costs. Similarly, projects with relatively low capital costs may 
not be cost effective if there are few emissions reduced.

   h. Impact analysis part 2: How should I analyze and report energy 
                                impacts?

    1. You should examine the energy requirements of the control 
technology and determine whether the use of that technology results in 
energy penalties or benefits. A source owner may, for example, benefit 
from the combustion of a concentrated gas stream rich in volatile 
organic compounds; on the other hand, more often extra fuel or 
electricity is required to power a control device or incinerate a dilute 
gas stream. If such benefits or penalties exist, they should be 
quantified to the extent practicable. Because energy penalties or 
benefits can usually be quantified in terms of additional cost or income 
to the source, the energy impacts analysis can, in most cases, simply be 
factored into the cost impacts analysis. The fact of energy use in and 
of itself does not disqualify a technology.
    2. Your energy impact analysis should consider only direct energy 
consumption and not indirect energy impacts. For example, you could 
estimate the direct energy impacts of the control alternative in units 
of energy consumption at the source (e.g., BTU, kWh, barrels of oil, 
tons of coal). The energy requirements of the control options should be 
shown in terms of total (and in certain cases, also incremental) energy 
costs per ton of pollutant removed. You can then convert these units 
into dollar costs and, where appropriate, factor these costs into the 
control cost analysis.
    3. You generally do not consider indirect energy impacts (such as 
energy to produce raw materials for construction of control equipment). 
However, if you determine, either independently or based on a showing by 
the source owner, that the indirect energy impact is unusual or 
significant and that the impact can be well quantified, you may consider 
the indirect impact.
    4. The energy impact analysis may also address concerns over the use 
of locally scarce fuels. The designation of a scarce fuel may vary from 
region to region. However, in general, a scarce fuel is one which is in 
short supply locally and can be better used for alternative purposes, or 
one which may not be reasonably available to the source either at the 
present time or in the near future.
    5. Finally, the energy impacts analysis may consider whether there 
are relative differences between alternatives regarding the use of 
locally or regionally available coal, and whether a given alternative 
would result in significant economic disruption or unemployment. For 
example, where two options are equally cost effective and achieve 
equivalent or similar emissions reductions, one option may be preferred 
if the other alternative results in significant disruption or 
unemployment.

     i. Impact analysis part 3: How do I analyze ``non-air quality 
                        environmental impacts?''

    1. In the non-air quality related environmental impacts portion of 
the BART analysis, you address environmental impacts other than air 
quality due to emissions of the pollutant in question. Such 
environmental impacts include solid or hazardous

[[Page 677]]

waste generation and discharges of polluted water from a control device.
    2. You should identify any significant or unusual environmental 
impacts associated with a control alternative that have the potential to 
affect the selection or elimination of a control alternative. Some 
control technologies may have potentially significant secondary 
environmental impacts. Scrubber effluent, for example, may affect water 
quality and land use. Alternatively, water availability may affect the 
feasibility and costs of wet scrubbers. Other examples of secondary 
environmental impacts could include hazardous waste discharges, such as 
spent catalysts or contaminated carbon. Generally, these types of 
environmental concerns become important when sensitive site-specific 
receptors exist or when the incremental emissions reductions potential 
of the more stringent control is only marginally greater than the next 
most-effective option. However, the fact that a control device creates 
liquid and solid waste that must be disposed of does not necessarily 
argue against selection of that technology as BART, particularly if the 
control device has been applied to similar facilities elsewhere and the 
solid or liquid waste is similar to those other applications. On the 
other hand, where you or the source owner can show that unusual 
circumstances at the proposed facility create greater problems than 
experienced elsewhere, this may provide a basis for the elimination of 
that control alternative as BART.
    3. The procedure for conducting an analysis of non-air quality 
environmental impacts should be made based on a consideration of site-
specific circumstances. If you propose to adopt the most stringent 
alternative, then it is not necessary to perform this analysis of 
environmental impacts for the entire list of technologies you ranked in 
Step 3. In general, the analysis need only address those control 
alternatives with any significant or unusual environmental impacts that 
have the potential to affect the selection of a control alternative, or 
elimination of a more stringent control alternative. Thus, any important 
relative environmental impacts (both positive and negative) of 
alternatives can be compared with each other.
    4. In general, the analysis of impacts starts with the 
identification and quantification of the solid, liquid, and gaseous 
discharges from the control device or devices under review. Initially, 
you should perform a qualitative or semi-quantitative screening to 
narrow the analysis to discharges with potential for causing adverse 
environmental effects. Next, you should assess the mass and composition 
of any such discharges and quantify them to the extent possible, based 
on readily available information. You should also assemble pertinent 
information about the public or environmental consequences of releasing 
these materials.

    j. Impact analysis part 4: What are examples of non-air quality 
                         environmental impacts?

    The following are examples of how to conduct non-air quality 
environmental impacts:
    (1) Water Impact
    You should identify the relative quantities of water used and water 
pollutants produced and discharged as a result of the use of each 
alternative emission control system. Where possible, you should assess 
the effect on ground water and such local surface water quality 
parameters as ph, turbidity, dissolved oxygen, salinity, toxic chemical 
levels, temperature, and any other important considerations. The 
analysis could consider whether applicable water quality standards will 
be met and the availability and effectiveness of various techniques to 
reduce potential adverse effects.
    (2) Solid Waste Disposal Impact
    You could also compare the quality and quantity of solid waste 
(e.g., sludges, solids) that must be stored and disposed of or recycled 
as a result of the application of each alternative emission control 
system. You should consider the composition and various other 
characteristics of the solid waste (such as permeability, water 
retention, rewatering of dried material, compression strength, 
leachability of dissolved ions, bulk density, ability to support 
vegetation growth and hazardous characteristics) which are significant 
with regard to potential surface water pollution or transport into and 
contamination of subsurface waters or aquifers.
    (3) Irreversible or Irretrievable Commitment of Resources
    You may consider the extent to which the alternative emission 
control systems may involve a trade-off between short-term environmental 
gains at the expense of long-term environmental losses and the extent to 
which the alternative systems may result in irreversible or 
irretrievable commitment of resources (for example, use of scarce water 
resources).
    (4) Other Adverse Environmental Impacts
    You may consider significant differences in noise levels, radiant 
heat, or dissipated static electrical energy of pollution control 
alternatives. Other examples of non-air quality environmental impacts 
would include hazardous waste discharges such as spent catalysts or 
contaminated carbon.

 k. How do I take into account a project's ``remaining useful life'' in 
                       calculating control costs?

    1. You may decide to treat the requirement to consider the source's 
``remaining useful life'' of the source for BART determinations as one 
element of the overall cost analysis. The ``remaining useful life'' of a 
source, if it

[[Page 678]]

represents a relatively short time period, may affect the annualized 
costs of retrofit controls. For example, the methods for calculating 
annualized costs in EPA's OAQPS Control Cost Manual require the use of a 
specified time period for amortization that varies based upon the type 
of control. If the remaining useful life will clearly exceed this time 
period, the remaining useful life has essentially no effect on control 
costs and on the BART determination process. Where the remaining useful 
life is less than the time period for amortizing costs, you should use 
this shorter time period in your cost calculations.
    2. For purposes of these guidelines, the remaining useful life is 
the difference between:
    (1) The date that controls will be put in place (capital and other 
construction costs incurred before controls are put in place can be 
rolled into the first year, as suggested in EPA's OAQPS Control Cost 
Manual); you are conducting the BART analysis; and
    (2) The date the facility permanently stops operations. Where this 
affects the BART determination, this date should be assured by a 
federally- or State-enforceable restriction preventing further 
operation.
    3. We recognize that there may be situations where a source operator 
intends to shut down a source by a given date, but wishes to retain the 
flexibility to continue operating beyond that date in the event, for 
example, that market conditions change. Where this is the case, your 
BART analysis may account for this, but it must maintain consistency 
with the statutory requirement to install BART within 5 years. Where the 
source chooses not to accept a federally enforceable condition requiring 
the source to shut down by a given date, it is necessary to determine 
whether a reduced time period for the remaining useful life changes the 
level of controls that would have been required as BART.
    If the reduced time period does change the level of BART controls, 
you may identify, and include as part of the BART emission limitation, 
the more stringent level of control that would be required as BART if 
there were no assumption that reduced the remaining useful life. You may 
incorporate into the BART emission limit this more stringent level, 
which would serve as a contingency should the source continue operating 
more than 5 years after the date EPA approves the relevant SIP. The 
source would not be allowed to operate after the 5-year mark without 
such controls. If a source does operate after the 5-year mark without 
BART in place, the source is considered to be in violation of the BART 
emissions limit for each day of operation.

    5. Step 5: How should I determine visibility impacts in the BART 
                             determination?

    The following is an approach you may use to determine visibility 
impacts (the degree of visibility improvement for each source subject to 
BART) for the BART determination. Once you have determined that your 
source or sources are subject to BART, you must conduct a visibility 
improvement determination for the source(s) as part of the BART 
determination. When making this determination, we believe you have 
flexibility in setting absolute thresholds, target levels of 
improvement, or de minimis levels since the deciview improvement must be 
weighed among the five factors, and you are free to determine the weight 
and significance to be assigned to each factor. For example, a 0.3 
deciview improvement may merit a stronger weighting in one case versus 
another, so one ``bright line'' may not be appropriate. [Note that if 
sources have elected to apply the most stringent controls available, 
consistent with the discussion in section E. step 1. below, you need not 
conduct, or require the source to conduct, an air quality modeling 
analysis for the purpose of determining its visibility impacts.]
    Use CALPUFF, \17\ or other appropriate dispersion model to determine 
the visibility improvement expected at a Class I area from the potential 
BART control technology applied to the source. Modeling should be 
conducted for SO2, NOX, and direct PM emissions 
(PM2.5 and/or PM10). If the source is making the 
visibility determination, you should review and approve or disapprove of 
the source's analysis before making the expected improvement 
determination. There are several steps for determining the visibility 
impacts from an individual source using a dispersion model:
---------------------------------------------------------------------------

    \17\ The model code and its documentation are available at no cost 
for download from http://www.epa.gov/scram001/tt22.htmcalpuff.
---------------------------------------------------------------------------

     Develop a modeling protocol.
    Some critical items to include in a modeling protocol are 
meteorological and terrain data, as well as source-specific information 
(stack height, temperature, exit velocity, elevation, and allowable and 
actual emission rates of applicable pollutants), and receptor data from 
appropriate Class I areas. We recommend following EPA's Interagency 
Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report and 
Recommendations for Modeling Long Range Transport Impacts \18\ for 
parameter settings and meteorological data inputs; the use of other 
settings from

[[Page 679]]

those in IWAQM should be identified and explained in the protocol.
---------------------------------------------------------------------------

    \18\ Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 
Summary Report and Recommendations for Modeling Long Range Transport 
Impacts, U.S. Environmental Protection Agency, EPA-454/R-98-019, 
December 1998.
---------------------------------------------------------------------------

    One important element of the protocol is in establishing the 
receptors that will be used in the model. The receptors that you use 
should be located in the nearest Class I area with sufficient density to 
identify the likely visibility effects of the source. For other Class I 
areas in relatively close proximity to a BART-eligible source, you may 
model a few strategic receptors to determine whether effects at those 
areas may be greater than at the nearest Class I area. For example, you 
might chose to locate receptors at these areas at the closest point to 
the source, at the highest and lowest elevation in the Class I area, at 
the IMPROVE monitor, and at the approximate expected plume release 
height. If the highest modeled effects are observed at the nearest Class 
I area, you may choose not to analyze the other Class I areas any 
further as additional analyses might be unwarranted.
    You should bear in mind that some receptors within the relevant 
Class I area may be less than 50 km from the source while other 
receptors within that same Class I area may be greater than 50 km from 
the same source. As indicated by the Guideline on Air Quality Models, 
this situation may call for the use of two different modeling approaches 
for the same Class I area and source, depending upon the State's chosen 
method for modeling sources less than 50 km. In situations where you are 
assessing visibility impacts for source-receptor distances less than 50 
km, you should use expert modeling judgment in determining visibility 
impacts, giving consideration to both CALPUFF and other EPA-approved 
methods.
    In developing your modeling protocol, you may want to consult with 
EPA and your regional planning organization (RPO). Up-front consultation 
will ensure that key technical issues are addressed before you conduct 
your modeling.
     For each source, run the model, at pre-control 
and post-control emission rates according to the accepted methodology in 
the protocol.
    Use the 24-hour average actual emission rate from the highest 
emitting day of the meteorological period modeled (for the pre-control 
scenario). Calculate the model results for each receptor as the change 
in deciviews compared against natural visibility conditions. Post-
control emission rates are calculated as a percentage of pre-control 
emission rates. For example, if the 24-hr pre-control emission rate is 
100 lb/hr of SO2, then the post control rate is 5 lb/hr if 
the control efficiency being evaluated is 95 percent.
     Make the net visibility improvement 
determination.
    Assess the visibility improvement based on the modeled change in 
visibility impacts for the pre-control and post-control emission 
scenarios. You have flexibility to assess visibility improvements due to 
BART controls by one or more methods. You may consider the frequency, 
magnitude, and duration components of impairment. Suggestions for making 
the determination are:
     Use of a comparison threshold, as is done for 
determining if BART-eligible sources should be subject to a BART 
determination. Comparison thresholds can be used in a number of ways in 
evaluating visibility improvement (e.g., the number of days or hours 
that the threshold was exceeded, a single threshold for determining 
whether a change in impacts is significant, or a threshold representing 
an x percent change in improvement).
     Compare the 98th percent days for the pre- and 
post-control runs.
    Note that each of the modeling options may be supplemented with 
source apportionment data or source apportionment modeling.

E. How do I select the ``best'' alternative, using the results of Steps 
                              1 through 5?

                   1. Summary of the Impacts Analysis

    From the alternatives you evaluated in Step 3, we recommend you 
develop a chart (or charts) displaying for each of the alternatives:
    (1) Expected emission rate (tons per year, pounds per hour);
    (2) Emissions performance level (e.g., percent pollutant removed, 
emissions per unit product, lb/MMBtu, ppm);
    (3) Expected emissions reductions (tons per year);
    (4) Costs of compliance--total annualized costs ($), cost 
effectiveness ($/ton), and incremental cost effectiveness ($/ton), and/
or any other cost-effectiveness measures (such as $/deciview);
    (5) Energy impacts;
    (6) Non-air quality environmental impacts; and
    (7) Modeled visibility impacts.

                   2. Selecting a ``best'' alternative

    1. You have discretion to determine the order in which you should 
evaluate control options for BART. Whatever the order in which you 
choose to evaluate options, you should always (1) display the options 
evaluated; (2) identify the average and incremental costs of each 
option; (3) consider the energy and non-air quality environmental 
impacts of each option; (4) consider the remaining useful life; and (5) 
consider the modeled visibility impacts. You should provide a 
justification for adopting the technology that you select as the 
``best'' level of control, including an explanation of the CAA factors 
that led you to choose that option over other control levels.

[[Page 680]]

    2. In the case where you are conducting a BART determination for two 
regulated pollutants on the same source, if the result is two different 
BART technologies that do not work well together, you could then 
substitute a different technology or combination of technologies.

     3. In selecting a ``best'' alternative, should I consider the 
                       affordability of controls?

    1. Even if the control technology is cost effective, there may be 
cases where the installation of controls would affect the viability of 
continued plant operations.
    2. There may be unusual circumstances that justify taking into 
consideration the conditions of the plant and the economic effects of 
requiring the use of a given control technology. These effects would 
include effects on product prices, the market share, and profitability 
of the source. Where there are such unusual circumstances that are 
judged to affect plant operations, you may take into consideration the 
conditions of the plant and the economic effects of requiring the use of 
a control technology. Where these effects are judged to have a severe 
impact on plant operations you may consider them in the selection 
process, but you may wish to provide an economic analysis that 
demonstrates, in sufficient detail for public review, the specific 
economic effects, parameters, and reasoning. (We recognize that this 
review process must preserve the confidentiality of sensitive business 
information). Any analysis may also consider whether other competing 
plants in the same industry have been required to install BART controls 
if this information is available.

              4. Sulfur dioxide limits for utility boilers

    You must require 750 MW power plants to meet specific control levels 
for SO2 of either 95 percent control or 0.15 lbs/MMBtu, for 
each EGU greater than 200 MW that is currently uncontrolled unless you 
determine that an alternative control level is justified based on a 
careful consideration of the statutory factors. Thus, for example, if 
the source demonstrates circumstances affecting its ability to cost-
effectively reduce its emissions, you should take that into account in 
determining whether the presumptive levels of control are appropriate 
for that facility. For a currently uncontrolled EGU greater than 200 MW 
in size, but located at a power plant smaller than 750 MW in size, such 
controls are generally cost-effective and could be used in your BART 
determination considering the five factors specified in CAA section 
169A(g)(2). While these levels may represent current control 
capabilities, we expect that scrubber technology will continue to 
improve and control costs continue to decline. You should be sure to 
consider the level of control that is currently best achievable at the 
time that you are conducting your BART analysis.
    For coal-fired EGUs with existing post-combustion SO2 
controls achieving less than 50 percent removal efficiencies, we 
recommend that you evaluate constructing a new FGD system to meet the 
same emission limits as above (95 percent removal or 0.15 lb/mmBtu), in 
addition to the evaluation of scrubber upgrades discussed below. For 
oil-fired units, regardless of size, you should evaluate limiting the 
sulfur content of the fuel oil burned to 1 percent or less by weight.
    For those BART-eligible EGUs with pre-existing post-combustion 
SO2 controls achieving removal efficiencies of at least 50 
percent, your BART determination should consider cost effective scrubber 
upgrades designed to improve the system's overall SO2 removal 
efficiency. There are numerous scrubber enhancements available to 
upgrade the average removal efficiencies of all types of existing 
scrubber systems. We recommend that as you evaluate the definition of 
``upgrade,'' you evaluate options that not only improve the design 
removal efficiency of the scrubber vessel itself, but also consider 
upgrades that can improve the overall SO2 removal efficiency 
of the scrubber system. Increasing a scrubber system's reliability, and 
conversely decreasing its downtime, by way of optimizing operation 
procedures, improving maintenance practices, adjusting scrubber 
chemistry, and increasing auxiliary equipment redundancy, are all ways 
to improve average SO2 removal efficiencies.
    We recommend that as you evaluate the performance of existing wet 
scrubber systems, you consider some of the following upgrades, in no 
particular order, as potential scrubber upgrades that have been proven 
in the industry as cost effective means to increase overall 
SO2 removal of wet systems:
    (a) Elimination of Bypass Reheat;
    (b) Installation of Liquid Distribution Rings;
    (c) Installation of Perforated Trays;
    (d) Use of Organic Acid Additives;
    (e) Improve or Upgrade Scrubber Auxiliary System Equipment;
    (f) Redesign Spray Header or Nozzle Configuration.
    We recommend that as you evaluate upgrade options for dry scrubber 
systems, you should consider the following cost effective upgrades, in 
no particular order:
    (a) Use of Performance Additives;
    (b) Use of more Reactive Sorbent;
    (c) Increase the Pulverization Level of Sorbent;
    (d) Engineering redesign of atomizer or slurry injection system.
    You should evaluate scrubber upgrade options based on the 5 step 
BART analysis process.

[[Page 681]]

              5. Nitrogen oxide limits for utility boilers

    You should establish specific numerical limits for NOX 
control for each BART determination. For power plants with a generating 
capacity in excess of 750 MW currently using selective catalytic 
reduction (SCR) or selective non-catalytic reduction (SNCR) for part of 
the year, you should presume that use of those same controls year-round 
is BART. For other sources currently using SCR or SNCR to reduce 
NOX emissions during part of the year, you should carefully 
consider requiring the use of these controls year-round as the 
additional costs of operating the equipment throughout the year would be 
relatively modest.
    For coal-fired EGUs greater than 200 MW located at greater than 750 
MW power plants and operating without post-combustion controls (i.e. SCR 
or SNCR), we have provided presumptive NOX limits, 
differentiated by boiler design and type of coal burned. You may 
determine that an alternative control level is appropriate based on a 
careful consideration of the statutory factors. For coal-fired EGUs 
greater than 200 MW located at power plants 750 MW or less in size and 
operating without post-combustion controls, you should likewise presume 
that these same levels are cost-effective. You should require such 
utility boilers to meet the following NOX emission limits, 
unless you determine that an alternative control level is justified 
based on consideration of the statutory factors. The following 
NOX emission rates were determined based on a number of 
assumptions, including that the EGU boiler has enough volume to allow 
for installation and effective operation of separated overfire air 
ports. For boilers where these assumptions are incorrect, these emission 
limits may not be cost-effective.

  Table 1--Presumptive NOX Emission Limits for BART-Eligible Coal-Fired
                               Units. \19\
------------------------------------------------------------------------
                                                         NOX presumptive
           Unit type                   Coal type        limit (lb/mmbtu)
                                                              \20\
------------------------------------------------------------------------
Dry-bottom wall-fired.........  Bituminous............              0.39
                                Sub-bituminous........              0.23
                                Lignite...............              0.29
Tangential-fired..............  Bituminous............              0.28
                                Sub-bituminous........              0.15
                                Lignite...............              0.17
Cell Burners..................  Bituminous............              0.40
                                Sub-bituminous........              0.45
Dry-turbo-fired...............  Bituminous............              0.32
                                Sub-bituminous........              0.23
Wet-bottom tangential-fired...  Bituminous............              0.62
------------------------------------------------------------------------
\19\ No Cell burners, dry-turbo-fired units, nor wet-bottom tangential-
  fired units burning lignite were identified as BART-eligible, thus no
  presumptive limit was determined. Similarly, no wet-bottom tangential-
  fired units burning sub-bituminous were identified as BART-eligible.
\20\ These limits reflect the design and technological assumptions
  discussed in the technical support document for NOX limits for these
  guidelines. See Technical Support Document for BART NOX Limits for
  Electric Generating Units and Technical Support Document for BART NOX
  Limits for Electric Generating Units Excel Spreadsheet, Memorandum to
  Docket OAR 2002-0076, April 15, 2005.

    Most EGUs can meet these presumptive NOX limits through 
the use of current combustion control technology, i.e. the careful 
control of combustion air and low-NOX burners. For units that 
cannot meet these limits using such technologies, you should consider 
whether advanced combustion control technologies such as rotating 
opposed fire air should be used to meet these limits.
    Because of the relatively high NOX emission rates of 
cyclone units, SCR is more cost-effective than the use of current 
combustion control technology for these units. The use of SCRs at 
cyclone units burning bituminous coal, sub-bituminous coal, and lignite 
should enable the units to cost-effectively meet NOX rates of 
0.10 lbs/mmbtu. As a result, we are establishing a presumptive 
NOX limit of 0.10 lbs/mmbtu based on the use of SCR for coal-
fired cyclone units greater than 200 MW located at 750 MW power plants. 
As with the other presumptive limits established in this guideline, you 
may determine that an alternative level of control is appropriate based 
on your consideration of the relevant statutory factors. For other 
cyclone units, you should review the use of SCR and consider whether 
these post-combustion controls should be required as BART.
    For oil-fired and gas-fired EGUs larger than 200MW, we believe that 
installation of current combustion control technology to control 
NOX is generally highly cost-effective and should be 
considered in your determination of BART for these sources. Many such 
units can make significant reductions

[[Page 682]]

in NOX emissions which are highly cost-effective through the 
application of current combustion control technology. \21\
---------------------------------------------------------------------------

    \21\ See Technical Support Document for BART NOX Limits for Electric 
Generating Units and Technical Support Document for BART NOX Limits for 
Electric Generating Units Excel Spreadsheet, Memorandum to Docket OAR 
2002-0076, April 15, 2005.
---------------------------------------------------------------------------

                  V. Enforceable Limits/Compliance Date

    To complete the BART process, you must establish enforceable 
emission limits that reflect the BART requirements and require 
compliance within a given period of time. In particular, you must 
establish an enforceable emission limit for each subject emission unit 
at the source and for each pollutant subject to review that is emitted 
from the source. In addition, you must require compliance with the BART 
emission limitations no later than 5 years after EPA approves your 
regional haze SIP. If technological or economic limitations in the 
application of a measurement methodology to a particular emission unit 
make a conventional emissions limit infeasible, you may instead 
prescribe a design, equipment, work practice, operation standard, or 
combination of these types of standards. You should consider allowing 
sources to ``average'' emissions across any set of BART-eligible 
emission units within a fenceline, so long as the emission reductions 
from each pollutant being controlled for BART would be equal to those 
reductions that would be obtained by simply controlling each of the 
BART-eligible units that constitute BART-eligible source.
    You should ensure that any BART requirements are written in a way 
that clearly specifies the individual emission unit(s) subject to BART 
regulation. Because the BART requirements themselves are ``applicable'' 
requirements of the CAA, they must be included as title V permit 
conditions according to the procedures established in 40 CFR part 70 or 
40 CFR part 71.
    Section 302(k) of the CAA requires emissions limits such as BART to 
be met on a continuous basis. Although this provision does not 
necessarily require the use of continuous emissions monitoring (CEMs), 
it is important that sources employ techniques that ensure compliance on 
a continuous basis. Monitoring requirements generally applicable to 
sources, including those that are subject to BART, are governed by other 
regulations. See, e.g., 40 CFR part 64 (compliance assurance 
monitoring); 40 CFR 70.6(a)(3) (periodic monitoring); 40 CFR 70.6(c)(1) 
(sufficiency monitoring). Note also that while we do not believe that 
CEMs would necessarily be required for all BART sources, the vast 
majority of electric generating units potentially subject to BART 
already employ CEM technology for other programs, such as the acid rain 
program. In addition, emissions limits must be enforceable as a 
practical matter (contain appropriate averaging times, compliance 
verification procedures and recordkeeping requirements). In light of the 
above, the permit must:
     Be sufficient to show compliance or noncompliance 
(i.e., through monitoring times of operation, fuel input, or other 
indices of operating conditions and practices); and
     Specify a reasonable averaging time consistent 
with established reference methods, contain reference methods for 
determining compliance, and provide for adequate reporting and 
recordkeeping so that air quality agency personnel can determine the 
compliance status of the source; and
     For EGUS, specify an averaging time of a 30-day 
rolling average, and contain a definition of ``boiler operating day'' 
that is consistent with the definition in the proposed revisions to the 
NSPS for utility boilers in 40 CFR Part 60, subpart Da. \22\ You should 
consider a boiler operating day to be any 24-hour period between 12:00 
midnight and the following midnight during which any fuel is combusted 
at any time at the steam generating unit. This would allow 30-day 
rolling average emission rates to be calculated consistently across 
sources.
---------------------------------------------------------------------------

    \22\ 70 FR 9705, February 28, 2005.

[70 FR 39156, July 6, 2005]

[[Page 683]]



                              FINDING AIDS




  --------------------------------------------------------------------

  A list of CFR titles, subtitles, chapters, subchapters and parts and 
an alphabetical list of agencies publishing in the CFR are included in 
the CFR Index and Finding Aids volume to the Code of Federal Regulations 
which is published separately and revised annually.


  Table of CFR Titles and Chapters
  Alphabetical List of Agencies Appearing in the CFR
  List of CFR Sections Affected

[[Page 685]]



                    Table of CFR Titles and Chapters




                      (Revised as of July 1, 2021)

                      Title 1--General Provisions

         I  Administrative Committee of the Federal Register 
                (Parts 1--49)
        II  Office of the Federal Register (Parts 50--299)
       III  Administrative Conference of the United States (Parts 
                300--399)
        IV  Miscellaneous Agencies (Parts 400--599)
        VI  National Capital Planning Commission (Parts 600--699)

                    Title 2--Grants and Agreements

            Subtitle A--Office of Management and Budget Guidance 
                for Grants and Agreements
         I  Office of Management and Budget Governmentwide 
                Guidance for Grants and Agreements (Parts 2--199)
        II  Office of Management and Budget Guidance (Parts 200--
                299)
            Subtitle B--Federal Agency Regulations for Grants and 
                Agreements
       III  Department of Health and Human Services (Parts 300--
                399)
        IV  Department of Agriculture (Parts 400--499)
        VI  Department of State (Parts 600--699)
       VII  Agency for International Development (Parts 700--799)
      VIII  Department of Veterans Affairs (Parts 800--899)
        IX  Department of Energy (Parts 900--999)
         X  Department of the Treasury (Parts 1000--1099)
        XI  Department of Defense (Parts 1100--1199)
       XII  Department of Transportation (Parts 1200--1299)
      XIII  Department of Commerce (Parts 1300--1399)
       XIV  Department of the Interior (Parts 1400--1499)
        XV  Environmental Protection Agency (Parts 1500--1599)
     XVIII  National Aeronautics and Space Administration (Parts 
                1800--1899)
        XX  United States Nuclear Regulatory Commission (Parts 
                2000--2099)
      XXII  Corporation for National and Community Service (Parts 
                2200--2299)
     XXIII  Social Security Administration (Parts 2300--2399)
      XXIV  Department of Housing and Urban Development (Parts 
                2400--2499)
       XXV  National Science Foundation (Parts 2500--2599)
      XXVI  National Archives and Records Administration (Parts 
                2600--2699)

[[Page 686]]

     XXVII  Small Business Administration (Parts 2700--2799)
    XXVIII  Department of Justice (Parts 2800--2899)
      XXIX  Department of Labor (Parts 2900--2999)
       XXX  Department of Homeland Security (Parts 3000--3099)
      XXXI  Institute of Museum and Library Services (Parts 3100--
                3199)
     XXXII  National Endowment for the Arts (Parts 3200--3299)
    XXXIII  National Endowment for the Humanities (Parts 3300--
                3399)
     XXXIV  Department of Education (Parts 3400--3499)
      XXXV  Export-Import Bank of the United States (Parts 3500--
                3599)
     XXXVI  Office of National Drug Control Policy, Executive 
                Office of the President (Parts 3600--3699)
    XXXVII  Peace Corps (Parts 3700--3799)
     LVIII  Election Assistance Commission (Parts 5800--5899)
       LIX  Gulf Coast Ecosystem Restoration Council (Parts 5900--
                5999)

                        Title 3--The President

         I  Executive Office of the President (Parts 100--199)

                           Title 4--Accounts

         I  Government Accountability Office (Parts 1--199)

                   Title 5--Administrative Personnel

         I  Office of Personnel Management (Parts 1--1199)
        II  Merit Systems Protection Board (Parts 1200--1299)
       III  Office of Management and Budget (Parts 1300--1399)
        IV  Office of Personnel Management and Office of the 
                Director of National Intelligence (Parts 1400--
                1499)
         V  The International Organizations Employees Loyalty 
                Board (Parts 1500--1599)
        VI  Federal Retirement Thrift Investment Board (Parts 
                1600--1699)
      VIII  Office of Special Counsel (Parts 1800--1899)
        IX  Appalachian Regional Commission (Parts 1900--1999)
        XI  Armed Forces Retirement Home (Parts 2100--2199)
       XIV  Federal Labor Relations Authority, General Counsel of 
                the Federal Labor Relations Authority and Federal 
                Service Impasses Panel (Parts 2400--2499)
       XVI  Office of Government Ethics (Parts 2600--2699)
       XXI  Department of the Treasury (Parts 3100--3199)
      XXII  Federal Deposit Insurance Corporation (Parts 3200--
                3299)
     XXIII  Department of Energy (Parts 3300--3399)
      XXIV  Federal Energy Regulatory Commission (Parts 3400--
                3499)
       XXV  Department of the Interior (Parts 3500--3599)
      XXVI  Department of Defense (Parts 3600--3699)

[[Page 687]]

    XXVIII  Department of Justice (Parts 3800--3899)
      XXIX  Federal Communications Commission (Parts 3900--3999)
       XXX  Farm Credit System Insurance Corporation (Parts 4000--
                4099)
      XXXI  Farm Credit Administration (Parts 4100--4199)
    XXXIII  U.S. International Development Finance Corporation 
                (Parts 4300--4399)
     XXXIV  Securities and Exchange Commission (Parts 4400--4499)
      XXXV  Office of Personnel Management (Parts 4500--4599)
     XXXVI  Department of Homeland Security (Parts 4600--4699)
    XXXVII  Federal Election Commission (Parts 4700--4799)
        XL  Interstate Commerce Commission (Parts 5000--5099)
       XLI  Commodity Futures Trading Commission (Parts 5100--
                5199)
      XLII  Department of Labor (Parts 5200--5299)
     XLIII  National Science Foundation (Parts 5300--5399)
       XLV  Department of Health and Human Services (Parts 5500--
                5599)
      XLVI  Postal Rate Commission (Parts 5600--5699)
     XLVII  Federal Trade Commission (Parts 5700--5799)
    XLVIII  Nuclear Regulatory Commission (Parts 5800--5899)
      XLIX  Federal Labor Relations Authority (Parts 5900--5999)
         L  Department of Transportation (Parts 6000--6099)
       LII  Export-Import Bank of the United States (Parts 6200--
                6299)
      LIII  Department of Education (Parts 6300--6399)
       LIV  Environmental Protection Agency (Parts 6400--6499)
        LV  National Endowment for the Arts (Parts 6500--6599)
       LVI  National Endowment for the Humanities (Parts 6600--
                6699)
      LVII  General Services Administration (Parts 6700--6799)
     LVIII  Board of Governors of the Federal Reserve System 
                (Parts 6800--6899)
       LIX  National Aeronautics and Space Administration (Parts 
                6900--6999)
        LX  United States Postal Service (Parts 7000--7099)
       LXI  National Labor Relations Board (Parts 7100--7199)
      LXII  Equal Employment Opportunity Commission (Parts 7200--
                7299)
     LXIII  Inter-American Foundation (Parts 7300--7399)
      LXIV  Merit Systems Protection Board (Parts 7400--7499)
       LXV  Department of Housing and Urban Development (Parts 
                7500--7599)
      LXVI  National Archives and Records Administration (Parts 
                7600--7699)
     LXVII  Institute of Museum and Library Services (Parts 7700--
                7799)
    LXVIII  Commission on Civil Rights (Parts 7800--7899)
      LXIX  Tennessee Valley Authority (Parts 7900--7999)
       LXX  Court Services and Offender Supervision Agency for the 
                District of Columbia (Parts 8000--8099)
      LXXI  Consumer Product Safety Commission (Parts 8100--8199)
    LXXIII  Department of Agriculture (Parts 8300--8399)

[[Page 688]]

     LXXIV  Federal Mine Safety and Health Review Commission 
                (Parts 8400--8499)
     LXXVI  Federal Retirement Thrift Investment Board (Parts 
                8600--8699)
    LXXVII  Office of Management and Budget (Parts 8700--8799)
      LXXX  Federal Housing Finance Agency (Parts 9000--9099)
   LXXXIII  Special Inspector General for Afghanistan 
                Reconstruction (Parts 9300--9399)
    LXXXIV  Bureau of Consumer Financial Protection (Parts 9400--
                9499)
    LXXXVI  National Credit Union Administration (Parts 9600--
                9699)
     XCVII  Department of Homeland Security Human Resources 
                Management System (Department of Homeland 
                Security--Office of Personnel Management) (Parts 
                9700--9799)
    XCVIII  Council of the Inspectors General on Integrity and 
                Efficiency (Parts 9800--9899)
      XCIX  Military Compensation and Retirement Modernization 
                Commission (Parts 9900--9999)
         C  National Council on Disability (Parts 10000--10049)
        CI  National Mediation Board (Parts 10100--10199)
       CII  U.S. Office of Special Counsel (Parts 10200--10299)

                      Title 6--Domestic Security

         I  Department of Homeland Security, Office of the 
                Secretary (Parts 1--199)
         X  Privacy and Civil Liberties Oversight Board (Parts 
                1000--1099)

                         Title 7--Agriculture

            Subtitle A--Office of the Secretary of Agriculture 
                (Parts 0--26)
            Subtitle B--Regulations of the Department of 
                Agriculture
         I  Agricultural Marketing Service (Standards, 
                Inspections, Marketing Practices), Department of 
                Agriculture (Parts 27--209)
        II  Food and Nutrition Service, Department of Agriculture 
                (Parts 210--299)
       III  Animal and Plant Health Inspection Service, Department 
                of Agriculture (Parts 300--399)
        IV  Federal Crop Insurance Corporation, Department of 
                Agriculture (Parts 400--499)
         V  Agricultural Research Service, Department of 
                Agriculture (Parts 500--599)
        VI  Natural Resources Conservation Service, Department of 
                Agriculture (Parts 600--699)
       VII  Farm Service Agency, Department of Agriculture (Parts 
                700--799)
      VIII  Agricultural Marketing Service (Federal Grain 
                Inspection Service, Fair Trade Practices Program), 
                Department of Agriculture (Parts 800--899)

[[Page 689]]

        IX  Agricultural Marketing Service (Marketing Agreements 
                and Orders; Fruits, Vegetables, Nuts), Department 
                of Agriculture (Parts 900--999)
         X  Agricultural Marketing Service (Marketing Agreements 
                and Orders; Milk), Department of Agriculture 
                (Parts 1000--1199)
        XI  Agricultural Marketing Service (Marketing Agreements 
                and Orders; Miscellaneous Commodities), Department 
                of Agriculture (Parts 1200--1299)
       XIV  Commodity Credit Corporation, Department of 
                Agriculture (Parts 1400--1499)
        XV  Foreign Agricultural Service, Department of 
                Agriculture (Parts 1500--1599)
       XVI  (Parts 1600--1699) [Reserved]
      XVII  Rural Utilities Service, Department of Agriculture 
                (Parts 1700--1799)
     XVIII  Rural Housing Service, Rural Business-Cooperative 
                Service, Rural Utilities Service, and Farm Service 
                Agency, Department of Agriculture (Parts 1800--
                2099)
        XX  (Parts 2200--2299) [Reserved]
       XXV  Office of Advocacy and Outreach, Department of 
                Agriculture (Parts 2500--2599)
      XXVI  Office of Inspector General, Department of Agriculture 
                (Parts 2600--2699)
     XXVII  Office of Information Resources Management, Department 
                of Agriculture (Parts 2700--2799)
    XXVIII  Office of Operations, Department of Agriculture (Parts 
                2800--2899)
      XXIX  Office of Energy Policy and New Uses, Department of 
                Agriculture (Parts 2900--2999)
       XXX  Office of the Chief Financial Officer, Department of 
                Agriculture (Parts 3000--3099)
      XXXI  Office of Environmental Quality, Department of 
                Agriculture (Parts 3100--3199)
     XXXII  Office of Procurement and Property Management, 
                Department of Agriculture (Parts 3200--3299)
    XXXIII  Office of Transportation, Department of Agriculture 
                (Parts 3300--3399)
     XXXIV  National Institute of Food and Agriculture (Parts 
                3400--3499)
      XXXV  Rural Housing Service, Department of Agriculture 
                (Parts 3500--3599)
     XXXVI  National Agricultural Statistics Service, Department 
                of Agriculture (Parts 3600--3699)
    XXXVII  Economic Research Service, Department of Agriculture 
                (Parts 3700--3799)
   XXXVIII  World Agricultural Outlook Board, Department of 
                Agriculture (Parts 3800--3899)
       XLI  [Reserved]
      XLII  Rural Business-Cooperative Service and Rural Utilities 
                Service, Department of Agriculture (Parts 4200--
                4299)

[[Page 690]]

         L  Rural Business-Cooperative Service, and Rural 
                Utilities Service, Department of Agriculture 
                (Parts 5000--5099)

                    Title 8--Aliens and Nationality

         I  Department of Homeland Security (Parts 1--499)
         V  Executive Office for Immigration Review, Department of 
                Justice (Parts 1000--1399)

                 Title 9--Animals and Animal Products

         I  Animal and Plant Health Inspection Service, Department 
                of Agriculture (Parts 1--199)
        II  Agricultural Marketing Service (Fair Trade Practices 
                Program), Department of Agriculture (Parts 200--
                299)
       III  Food Safety and Inspection Service, Department of 
                Agriculture (Parts 300--599)

                           Title 10--Energy

         I  Nuclear Regulatory Commission (Parts 0--199)
        II  Department of Energy (Parts 200--699)
       III  Department of Energy (Parts 700--999)
         X  Department of Energy (General Provisions) (Parts 
                1000--1099)
      XIII  Nuclear Waste Technical Review Board (Parts 1300--
                1399)
      XVII  Defense Nuclear Facilities Safety Board (Parts 1700--
                1799)
     XVIII  Northeast Interstate Low-Level Radioactive Waste 
                Commission (Parts 1800--1899)

                      Title 11--Federal Elections

         I  Federal Election Commission (Parts 1--9099)
        II  Election Assistance Commission (Parts 9400--9499)

                      Title 12--Banks and Banking

         I  Comptroller of the Currency, Department of the 
                Treasury (Parts 1--199)
        II  Federal Reserve System (Parts 200--299)
       III  Federal Deposit Insurance Corporation (Parts 300--399)
        IV  Export-Import Bank of the United States (Parts 400--
                499)
         V  (Parts 500--599) [Reserved]
        VI  Farm Credit Administration (Parts 600--699)
       VII  National Credit Union Administration (Parts 700--799)
      VIII  Federal Financing Bank (Parts 800--899)
        IX  (Parts 900--999) [Reserved]
         X  Bureau of Consumer Financial Protection (Parts 1000--
                1099)

[[Page 691]]

        XI  Federal Financial Institutions Examination Council 
                (Parts 1100--1199)
       XII  Federal Housing Finance Agency (Parts 1200--1299)
      XIII  Financial Stability Oversight Council (Parts 1300--
                1399)
       XIV  Farm Credit System Insurance Corporation (Parts 1400--
                1499)
        XV  Department of the Treasury (Parts 1500--1599)
       XVI  Office of Financial Research, Department of the 
                Treasury (Parts 1600--1699)
      XVII  Office of Federal Housing Enterprise Oversight, 
                Department of Housing and Urban Development (Parts 
                1700--1799)
     XVIII  Community Development Financial Institutions Fund, 
                Department of the Treasury (Parts 1800--1899)

               Title 13--Business Credit and Assistance

         I  Small Business Administration (Parts 1--199)
       III  Economic Development Administration, Department of 
                Commerce (Parts 300--399)
        IV  Emergency Steel Guarantee Loan Board (Parts 400--499)
         V  Emergency Oil and Gas Guaranteed Loan Board (Parts 
                500--599)

                    Title 14--Aeronautics and Space

         I  Federal Aviation Administration, Department of 
                Transportation (Parts 1--199)
        II  Office of the Secretary, Department of Transportation 
                (Aviation Proceedings) (Parts 200--399)
       III  Commercial Space Transportation, Federal Aviation 
                Administration, Department of Transportation 
                (Parts 400--1199)
         V  National Aeronautics and Space Administration (Parts 
                1200--1299)
        VI  Air Transportation System Stabilization (Parts 1300--
                1399)

                 Title 15--Commerce and Foreign Trade

            Subtitle A--Office of the Secretary of Commerce (Parts 
                0--29)
            Subtitle B--Regulations Relating to Commerce and 
                Foreign Trade
         I  Bureau of the Census, Department of Commerce (Parts 
                30--199)
        II  National Institute of Standards and Technology, 
                Department of Commerce (Parts 200--299)
       III  International Trade Administration, Department of 
                Commerce (Parts 300--399)
        IV  Foreign-Trade Zones Board, Department of Commerce 
                (Parts 400--499)
       VII  Bureau of Industry and Security, Department of 
                Commerce (Parts 700--799)

[[Page 692]]

      VIII  Bureau of Economic Analysis, Department of Commerce 
                (Parts 800--899)
        IX  National Oceanic and Atmospheric Administration, 
                Department of Commerce (Parts 900--999)
        XI  National Technical Information Service, Department of 
                Commerce (Parts 1100--1199)
      XIII  East-West Foreign Trade Board (Parts 1300--1399)
       XIV  Minority Business Development Agency (Parts 1400--
                1499)
        XV  Office of the Under-Secretary for Economic Affairs, 
                Department of Commerce (Parts 1500--1599)
            Subtitle C--Regulations Relating to Foreign Trade 
                Agreements
        XX  Office of the United States Trade Representative 
                (Parts 2000--2099)
            Subtitle D--Regulations Relating to Telecommunications 
                and Information
     XXIII  National Telecommunications and Information 
                Administration, Department of Commerce (Parts 
                2300--2399) [Reserved]

                    Title 16--Commercial Practices

         I  Federal Trade Commission (Parts 0--999)
        II  Consumer Product Safety Commission (Parts 1000--1799)

             Title 17--Commodity and Securities Exchanges

         I  Commodity Futures Trading Commission (Parts 1--199)
        II  Securities and Exchange Commission (Parts 200--399)
        IV  Department of the Treasury (Parts 400--499)

          Title 18--Conservation of Power and Water Resources

         I  Federal Energy Regulatory Commission, Department of 
                Energy (Parts 1--399)
       III  Delaware River Basin Commission (Parts 400--499)
        VI  Water Resources Council (Parts 700--799)
      VIII  Susquehanna River Basin Commission (Parts 800--899)
      XIII  Tennessee Valley Authority (Parts 1300--1399)

                       Title 19--Customs Duties

         I  U.S. Customs and Border Protection, Department of 
                Homeland Security; Department of the Treasury 
                (Parts 0--199)
        II  United States International Trade Commission (Parts 
                200--299)
       III  International Trade Administration, Department of 
                Commerce (Parts 300--399)
        IV  U.S. Immigration and Customs Enforcement, Department 
                of Homeland Security (Parts 400--599) [Reserved]

[[Page 693]]

                     Title 20--Employees' Benefits

         I  Office of Workers' Compensation Programs, Department 
                of Labor (Parts 1--199)
        II  Railroad Retirement Board (Parts 200--399)
       III  Social Security Administration (Parts 400--499)
        IV  Employees' Compensation Appeals Board, Department of 
                Labor (Parts 500--599)
         V  Employment and Training Administration, Department of 
                Labor (Parts 600--699)
        VI  Office of Workers' Compensation Programs, Department 
                of Labor (Parts 700--799)
       VII  Benefits Review Board, Department of Labor (Parts 
                800--899)
      VIII  Joint Board for the Enrollment of Actuaries (Parts 
                900--999)
        IX  Office of the Assistant Secretary for Veterans' 
                Employment and Training Service, Department of 
                Labor (Parts 1000--1099)

                       Title 21--Food and Drugs

         I  Food and Drug Administration, Department of Health and 
                Human Services (Parts 1--1299)
        II  Drug Enforcement Administration, Department of Justice 
                (Parts 1300--1399)
       III  Office of National Drug Control Policy (Parts 1400--
                1499)

                      Title 22--Foreign Relations

         I  Department of State (Parts 1--199)
        II  Agency for International Development (Parts 200--299)
       III  Peace Corps (Parts 300--399)
        IV  International Joint Commission, United States and 
                Canada (Parts 400--499)
         V  United States Agency for Global Media (Parts 500--599)
       VII  U.S. International Development Finance Corporation 
                (Parts 700--799)
        IX  Foreign Service Grievance Board (Parts 900--999)
         X  Inter-American Foundation (Parts 1000--1099)
        XI  International Boundary and Water Commission, United 
                States and Mexico, United States Section (Parts 
                1100--1199)
       XII  United States International Development Cooperation 
                Agency (Parts 1200--1299)
      XIII  Millennium Challenge Corporation (Parts 1300--1399)
       XIV  Foreign Service Labor Relations Board; Federal Labor 
                Relations Authority; General Counsel of the 
                Federal Labor Relations Authority; and the Foreign 
                Service Impasse Disputes Panel (Parts 1400--1499)
        XV  African Development Foundation (Parts 1500--1599)
       XVI  Japan-United States Friendship Commission (Parts 
                1600--1699)
      XVII  United States Institute of Peace (Parts 1700--1799)

[[Page 694]]

                          Title 23--Highways

         I  Federal Highway Administration, Department of 
                Transportation (Parts 1--999)
        II  National Highway Traffic Safety Administration and 
                Federal Highway Administration, Department of 
                Transportation (Parts 1200--1299)
       III  National Highway Traffic Safety Administration, 
                Department of Transportation (Parts 1300--1399)

                Title 24--Housing and Urban Development

            Subtitle A--Office of the Secretary, Department of 
                Housing and Urban Development (Parts 0--99)
            Subtitle B--Regulations Relating to Housing and Urban 
                Development
         I  Office of Assistant Secretary for Equal Opportunity, 
                Department of Housing and Urban Development (Parts 
                100--199)
        II  Office of Assistant Secretary for Housing-Federal 
                Housing Commissioner, Department of Housing and 
                Urban Development (Parts 200--299)
       III  Government National Mortgage Association, Department 
                of Housing and Urban Development (Parts 300--399)
        IV  Office of Housing and Office of Multifamily Housing 
                Assistance Restructuring, Department of Housing 
                and Urban Development (Parts 400--499)
         V  Office of Assistant Secretary for Community Planning 
                and Development, Department of Housing and Urban 
                Development (Parts 500--599)
        VI  Office of Assistant Secretary for Community Planning 
                and Development, Department of Housing and Urban 
                Development (Parts 600--699) [Reserved]
       VII  Office of the Secretary, Department of Housing and 
                Urban Development (Housing Assistance Programs and 
                Public and Indian Housing Programs) (Parts 700--
                799)
      VIII  Office of the Assistant Secretary for Housing--Federal 
                Housing Commissioner, Department of Housing and 
                Urban Development (Section 8 Housing Assistance 
                Programs, Section 202 Direct Loan Program, Section 
                202 Supportive Housing for the Elderly Program and 
                Section 811 Supportive Housing for Persons With 
                Disabilities Program) (Parts 800--899)
        IX  Office of Assistant Secretary for Public and Indian 
                Housing, Department of Housing and Urban 
                Development (Parts 900--1699)
         X  Office of Assistant Secretary for Housing--Federal 
                Housing Commissioner, Department of Housing and 
                Urban Development (Interstate Land Sales 
                Registration Program) (Parts 1700--1799) 
                [Reserved]
       XII  Office of Inspector General, Department of Housing and 
                Urban Development (Parts 2000--2099)
        XV  Emergency Mortgage Insurance and Loan Programs, 
                Department of Housing and Urban Development (Parts 
                2700--2799) [Reserved]

[[Page 695]]

        XX  Office of Assistant Secretary for Housing--Federal 
                Housing Commissioner, Department of Housing and 
                Urban Development (Parts 3200--3899)
      XXIV  Board of Directors of the HOPE for Homeowners Program 
                (Parts 4000--4099) [Reserved]
       XXV  Neighborhood Reinvestment Corporation (Parts 4100--
                4199)

                           Title 25--Indians

         I  Bureau of Indian Affairs, Department of the Interior 
                (Parts 1--299)
        II  Indian Arts and Crafts Board, Department of the 
                Interior (Parts 300--399)
       III  National Indian Gaming Commission, Department of the 
                Interior (Parts 500--599)
        IV  Office of Navajo and Hopi Indian Relocation (Parts 
                700--899)
         V  Bureau of Indian Affairs, Department of the Interior, 
                and Indian Health Service, Department of Health 
                and Human Services (Part 900--999)
        VI  Office of the Assistant Secretary, Indian Affairs, 
                Department of the Interior (Parts 1000--1199)
       VII  Office of the Special Trustee for American Indians, 
                Department of the Interior (Parts 1200--1299)

                      Title 26--Internal Revenue

         I  Internal Revenue Service, Department of the Treasury 
                (Parts 1--End)

           Title 27--Alcohol, Tobacco Products and Firearms

         I  Alcohol and Tobacco Tax and Trade Bureau, Department 
                of the Treasury (Parts 1--399)
        II  Bureau of Alcohol, Tobacco, Firearms, and Explosives, 
                Department of Justice (Parts 400--799)

                   Title 28--Judicial Administration

         I  Department of Justice (Parts 0--299)
       III  Federal Prison Industries, Inc., Department of Justice 
                (Parts 300--399)
         V  Bureau of Prisons, Department of Justice (Parts 500--
                599)
        VI  Offices of Independent Counsel, Department of Justice 
                (Parts 600--699)
       VII  Office of Independent Counsel (Parts 700--799)
      VIII  Court Services and Offender Supervision Agency for the 
                District of Columbia (Parts 800--899)
        IX  National Crime Prevention and Privacy Compact Council 
                (Parts 900--999)

[[Page 696]]

        XI  Department of Justice and Department of State (Parts 
                1100--1199)

                            Title 29--Labor

            Subtitle A--Office of the Secretary of Labor (Parts 
                0--99)
            Subtitle B--Regulations Relating to Labor
         I  National Labor Relations Board (Parts 100--199)
        II  Office of Labor-Management Standards, Department of 
                Labor (Parts 200--299)
       III  National Railroad Adjustment Board (Parts 300--399)
        IV  Office of Labor-Management Standards, Department of 
                Labor (Parts 400--499)
         V  Wage and Hour Division, Department of Labor (Parts 
                500--899)
        IX  Construction Industry Collective Bargaining Commission 
                (Parts 900--999)
         X  National Mediation Board (Parts 1200--1299)
       XII  Federal Mediation and Conciliation Service (Parts 
                1400--1499)
       XIV  Equal Employment Opportunity Commission (Parts 1600--
                1699)
      XVII  Occupational Safety and Health Administration, 
                Department of Labor (Parts 1900--1999)
        XX  Occupational Safety and Health Review Commission 
                (Parts 2200--2499)
       XXV  Employee Benefits Security Administration, Department 
                of Labor (Parts 2500--2599)
     XXVII  Federal Mine Safety and Health Review Commission 
                (Parts 2700--2799)
        XL  Pension Benefit Guaranty Corporation (Parts 4000--
                4999)

                      Title 30--Mineral Resources

         I  Mine Safety and Health Administration, Department of 
                Labor (Parts 1--199)
        II  Bureau of Safety and Environmental Enforcement, 
                Department of the Interior (Parts 200--299)
        IV  Geological Survey, Department of the Interior (Parts 
                400--499)
         V  Bureau of Ocean Energy Management, Department of the 
                Interior (Parts 500--599)
       VII  Office of Surface Mining Reclamation and Enforcement, 
                Department of the Interior (Parts 700--999)
       XII  Office of Natural Resources Revenue, Department of the 
                Interior (Parts 1200--1299)

                 Title 31--Money and Finance: Treasury

            Subtitle A--Office of the Secretary of the Treasury 
                (Parts 0--50)
            Subtitle B--Regulations Relating to Money and Finance

[[Page 697]]

         I  Monetary Offices, Department of the Treasury (Parts 
                51--199)
        II  Fiscal Service, Department of the Treasury (Parts 
                200--399)
        IV  Secret Service, Department of the Treasury (Parts 
                400--499)
         V  Office of Foreign Assets Control, Department of the 
                Treasury (Parts 500--599)
        VI  Bureau of Engraving and Printing, Department of the 
                Treasury (Parts 600--699)
       VII  Federal Law Enforcement Training Center, Department of 
                the Treasury (Parts 700--799)
      VIII  Office of Investment Security, Department of the 
                Treasury (Parts 800--899)
        IX  Federal Claims Collection Standards (Department of the 
                Treasury--Department of Justice) (Parts 900--999)
         X  Financial Crimes Enforcement Network, Department of 
                the Treasury (Parts 1000--1099)

                      Title 32--National Defense

            Subtitle A--Department of Defense
         I  Office of the Secretary of Defense (Parts 1--399)
         V  Department of the Army (Parts 400--699)
        VI  Department of the Navy (Parts 700--799)
       VII  Department of the Air Force (Parts 800--1099)
            Subtitle B--Other Regulations Relating to National 
                Defense
       XII  Department of Defense, Defense Logistics Agency (Parts 
                1200--1299)
       XVI  Selective Service System (Parts 1600--1699)
      XVII  Office of the Director of National Intelligence (Parts 
                1700--1799)
     XVIII  National Counterintelligence Center (Parts 1800--1899)
       XIX  Central Intelligence Agency (Parts 1900--1999)
        XX  Information Security Oversight Office, National 
                Archives and Records Administration (Parts 2000--
                2099)
       XXI  National Security Council (Parts 2100--2199)
      XXIV  Office of Science and Technology Policy (Parts 2400--
                2499)
     XXVII  Office for Micronesian Status Negotiations (Parts 
                2700--2799)
    XXVIII  Office of the Vice President of the United States 
                (Parts 2800--2899)

               Title 33--Navigation and Navigable Waters

         I  Coast Guard, Department of Homeland Security (Parts 
                1--199)
        II  Corps of Engineers, Department of the Army, Department 
                of Defense (Parts 200--399)
        IV  Great Lakes St. Lawrence Seaway Development 
                Corporation, Department of Transportation (Parts 
                400--499)

[[Page 698]]

                          Title 34--Education

            Subtitle A--Office of the Secretary, Department of 
                Education (Parts 1--99)
            Subtitle B--Regulations of the Offices of the 
                Department of Education
         I  Office for Civil Rights, Department of Education 
                (Parts 100--199)
        II  Office of Elementary and Secondary Education, 
                Department of Education (Parts 200--299)
       III  Office of Special Education and Rehabilitative 
                Services, Department of Education (Parts 300--399)
        IV  Office of Career, Technical, and Adult Education, 
                Department of Education (Parts 400--499)
         V  Office of Bilingual Education and Minority Languages 
                Affairs, Department of Education (Parts 500--599) 
                [Reserved]
        VI  Office of Postsecondary Education, Department of 
                Education (Parts 600--699)
       VII  Office of Educational Research and Improvement, 
                Department of Education (Parts 700--799) 
                [Reserved]
            Subtitle C--Regulations Relating to Education
        XI  (Parts 1100--1199) [Reserved]
       XII  National Council on Disability (Parts 1200--1299)

                          Title 35 [Reserved]

             Title 36--Parks, Forests, and Public Property

         I  National Park Service, Department of the Interior 
                (Parts 1--199)
        II  Forest Service, Department of Agriculture (Parts 200--
                299)
       III  Corps of Engineers, Department of the Army (Parts 
                300--399)
        IV  American Battle Monuments Commission (Parts 400--499)
         V  Smithsonian Institution (Parts 500--599)
        VI  [Reserved]
       VII  Library of Congress (Parts 700--799)
      VIII  Advisory Council on Historic Preservation (Parts 800--
                899)
        IX  Pennsylvania Avenue Development Corporation (Parts 
                900--999)
         X  Presidio Trust (Parts 1000--1099)
        XI  Architectural and Transportation Barriers Compliance 
                Board (Parts 1100--1199)
       XII  National Archives and Records Administration (Parts 
                1200--1299)
        XV  Oklahoma City National Memorial Trust (Parts 1500--
                1599)
       XVI  Morris K. Udall Scholarship and Excellence in National 
                Environmental Policy Foundation (Parts 1600--1699)

             Title 37--Patents, Trademarks, and Copyrights

         I  United States Patent and Trademark Office, Department 
                of Commerce (Parts 1--199)
        II  U.S. Copyright Office, Library of Congress (Parts 
                200--299)

[[Page 699]]

       III  Copyright Royalty Board, Library of Congress (Parts 
                300--399)
        IV  National Institute of Standards and Technology, 
                Department of Commerce (Parts 400--599)

           Title 38--Pensions, Bonuses, and Veterans' Relief

         I  Department of Veterans Affairs (Parts 0--199)
        II  Armed Forces Retirement Home (Parts 200--299)

                       Title 39--Postal Service

         I  United States Postal Service (Parts 1--999)
       III  Postal Regulatory Commission (Parts 3000--3099)

                  Title 40--Protection of Environment

         I  Environmental Protection Agency (Parts 1--1099)
        IV  Environmental Protection Agency and Department of 
                Justice (Parts 1400--1499)
         V  Council on Environmental Quality (Parts 1500--1599)
        VI  Chemical Safety and Hazard Investigation Board (Parts 
                1600--1699)
       VII  Environmental Protection Agency and Department of 
                Defense; Uniform National Discharge Standards for 
                Vessels of the Armed Forces (Parts 1700--1799)
      VIII  Gulf Coast Ecosystem Restoration Council (Parts 1800--
                1899)
        IX  Federal Permitting Improvement Steering Council (Part 
                1900)

          Title 41--Public Contracts and Property Management

            Subtitle A--Federal Procurement Regulations System 
                [Note]
            Subtitle B--Other Provisions Relating to Public 
                Contracts
        50  Public Contracts, Department of Labor (Parts 50-1--50-
                999)
        51  Committee for Purchase From People Who Are Blind or 
                Severely Disabled (Parts 51-1--51-99)
        60  Office of Federal Contract Compliance Programs, Equal 
                Employment Opportunity, Department of Labor (Parts 
                60-1--60-999)
        61  Office of the Assistant Secretary for Veterans' 
                Employment and Training Service, Department of 
                Labor (Parts 61-1--61-999)
   62--100  [Reserved]
            Subtitle C--Federal Property Management Regulations 
                System
       101  Federal Property Management Regulations (Parts 101-1--
                101-99)
       102  Federal Management Regulation (Parts 102-1--102-299)
  103--104  [Reserved]
       105  General Services Administration (Parts 105-1--105-999)

[[Page 700]]

       109  Department of Energy Property Management Regulations 
                (Parts 109-1--109-99)
       114  Department of the Interior (Parts 114-1--114-99)
       115  Environmental Protection Agency (Parts 115-1--115-99)
       128  Department of Justice (Parts 128-1--128-99)
  129--200  [Reserved]
            Subtitle D--Other Provisions Relating to Property 
                Management [Reserved]
            Subtitle E--Federal Information Resources Management 
                Regulations System [Reserved]
            Subtitle F--Federal Travel Regulation System
       300  General (Parts 300-1--300-99)
       301  Temporary Duty (TDY) Travel Allowances (Parts 301-1--
                301-99)
       302  Relocation Allowances (Parts 302-1--302-99)
       303  Payment of Expenses Connected with the Death of 
                Certain Employees (Part 303-1--303-99)
       304  Payment of Travel Expenses from a Non-Federal Source 
                (Parts 304-1--304-99)

                        Title 42--Public Health

         I  Public Health Service, Department of Health and Human 
                Services (Parts 1--199)
   II--III  [Reserved]
        IV  Centers for Medicare & Medicaid Services, Department 
                of Health and Human Services (Parts 400--699)
         V  Office of Inspector General-Health Care, Department of 
                Health and Human Services (Parts 1000--1099)

                   Title 43--Public Lands: Interior

            Subtitle A--Office of the Secretary of the Interior 
                (Parts 1--199)
            Subtitle B--Regulations Relating to Public Lands
         I  Bureau of Reclamation, Department of the Interior 
                (Parts 400--999)
        II  Bureau of Land Management, Department of the Interior 
                (Parts 1000--9999)
       III  Utah Reclamation Mitigation and Conservation 
                Commission (Parts 10000--10099)

             Title 44--Emergency Management and Assistance

         I  Federal Emergency Management Agency, Department of 
                Homeland Security (Parts 0--399)
        IV  Department of Commerce and Department of 
                Transportation (Parts 400--499)

[[Page 701]]

                       Title 45--Public Welfare

            Subtitle A--Department of Health and Human Services 
                (Parts 1--199)
            Subtitle B--Regulations Relating to Public Welfare
        II  Office of Family Assistance (Assistance Programs), 
                Administration for Children and Families, 
                Department of Health and Human Services (Parts 
                200--299)
       III  Office of Child Support Enforcement (Child Support 
                Enforcement Program), Administration for Children 
                and Families, Department of Health and Human 
                Services (Parts 300--399)
        IV  Office of Refugee Resettlement, Administration for 
                Children and Families, Department of Health and 
                Human Services (Parts 400--499)
         V  Foreign Claims Settlement Commission of the United 
                States, Department of Justice (Parts 500--599)
        VI  National Science Foundation (Parts 600--699)
       VII  Commission on Civil Rights (Parts 700--799)
      VIII  Office of Personnel Management (Parts 800--899)
        IX  Denali Commission (Parts 900--999)
         X  Office of Community Services, Administration for 
                Children and Families, Department of Health and 
                Human Services (Parts 1000--1099)
        XI  National Foundation on the Arts and the Humanities 
                (Parts 1100--1199)
       XII  Corporation for National and Community Service (Parts 
                1200--1299)
      XIII  Administration for Children and Families, Department 
                of Health and Human Services (Parts 1300--1399)
       XVI  Legal Services Corporation (Parts 1600--1699)
      XVII  National Commission on Libraries and Information 
                Science (Parts 1700--1799)
     XVIII  Harry S. Truman Scholarship Foundation (Parts 1800--
                1899)
       XXI  Commission of Fine Arts (Parts 2100--2199)
     XXIII  Arctic Research Commission (Parts 2300--2399)
      XXIV  James Madison Memorial Fellowship Foundation (Parts 
                2400--2499)
       XXV  Corporation for National and Community Service (Parts 
                2500--2599)

                          Title 46--Shipping

         I  Coast Guard, Department of Homeland Security (Parts 
                1--199)
        II  Maritime Administration, Department of Transportation 
                (Parts 200--399)
       III  Coast Guard (Great Lakes Pilotage), Department of 
                Homeland Security (Parts 400--499)
        IV  Federal Maritime Commission (Parts 500--599)

[[Page 702]]

                      Title 47--Telecommunication

         I  Federal Communications Commission (Parts 0--199)
        II  Office of Science and Technology Policy and National 
                Security Council (Parts 200--299)
       III  National Telecommunications and Information 
                Administration, Department of Commerce (Parts 
                300--399)
        IV  National Telecommunications and Information 
                Administration, Department of Commerce, and 
                National Highway Traffic Safety Administration, 
                Department of Transportation (Parts 400--499)
         V  The First Responder Network Authority (Parts 500--599)

           Title 48--Federal Acquisition Regulations System

         1  Federal Acquisition Regulation (Parts 1--99)
         2  Defense Acquisition Regulations System, Department of 
                Defense (Parts 200--299)
         3  Department of Health and Human Services (Parts 300--
                399)
         4  Department of Agriculture (Parts 400--499)
         5  General Services Administration (Parts 500--599)
         6  Department of State (Parts 600--699)
         7  Agency for International Development (Parts 700--799)
         8  Department of Veterans Affairs (Parts 800--899)
         9  Department of Energy (Parts 900--999)
        10  Department of the Treasury (Parts 1000--1099)
        12  Department of Transportation (Parts 1200--1299)
        13  Department of Commerce (Parts 1300--1399)
        14  Department of the Interior (Parts 1400--1499)
        15  Environmental Protection Agency (Parts 1500--1599)
        16  Office of Personnel Management Federal Employees 
                Health Benefits Acquisition Regulation (Parts 
                1600--1699)
        17  Office of Personnel Management (Parts 1700--1799)
        18  National Aeronautics and Space Administration (Parts 
                1800--1899)
        19  Broadcasting Board of Governors (Parts 1900--1999)
        20  Nuclear Regulatory Commission (Parts 2000--2099)
        21  Office of Personnel Management, Federal Employees 
                Group Life Insurance Federal Acquisition 
                Regulation (Parts 2100--2199)
        23  Social Security Administration (Parts 2300--2399)
        24  Department of Housing and Urban Development (Parts 
                2400--2499)
        25  National Science Foundation (Parts 2500--2599)
        28  Department of Justice (Parts 2800--2899)
        29  Department of Labor (Parts 2900--2999)
        30  Department of Homeland Security, Homeland Security 
                Acquisition Regulation (HSAR) (Parts 3000--3099)
        34  Department of Education Acquisition Regulation (Parts 
                3400--3499)

[[Page 703]]

        51  Department of the Army Acquisition Regulations (Parts 
                5100--5199) [Reserved]
        52  Department of the Navy Acquisition Regulations (Parts 
                5200--5299)
        53  Department of the Air Force Federal Acquisition 
                Regulation Supplement (Parts 5300--5399) 
                [Reserved]
        54  Defense Logistics Agency, Department of Defense (Parts 
                5400--5499)
        57  African Development Foundation (Parts 5700--5799)
        61  Civilian Board of Contract Appeals, General Services 
                Administration (Parts 6100--6199)
        99  Cost Accounting Standards Board, Office of Federal 
                Procurement Policy, Office of Management and 
                Budget (Parts 9900--9999)

                       Title 49--Transportation

            Subtitle A--Office of the Secretary of Transportation 
                (Parts 1--99)
            Subtitle B--Other Regulations Relating to 
                Transportation
         I  Pipeline and Hazardous Materials Safety 
                Administration, Department of Transportation 
                (Parts 100--199)
        II  Federal Railroad Administration, Department of 
                Transportation (Parts 200--299)
       III  Federal Motor Carrier Safety Administration, 
                Department of Transportation (Parts 300--399)
        IV  Coast Guard, Department of Homeland Security (Parts 
                400--499)
         V  National Highway Traffic Safety Administration, 
                Department of Transportation (Parts 500--599)
        VI  Federal Transit Administration, Department of 
                Transportation (Parts 600--699)
       VII  National Railroad Passenger Corporation (AMTRAK) 
                (Parts 700--799)
      VIII  National Transportation Safety Board (Parts 800--999)
         X  Surface Transportation Board (Parts 1000--1399)
        XI  Research and Innovative Technology Administration, 
                Department of Transportation (Parts 1400--1499) 
                [Reserved]
       XII  Transportation Security Administration, Department of 
                Homeland Security (Parts 1500--1699)

                   Title 50--Wildlife and Fisheries

         I  United States Fish and Wildlife Service, Department of 
                the Interior (Parts 1--199)
        II  National Marine Fisheries Service, National Oceanic 
                and Atmospheric Administration, Department of 
                Commerce (Parts 200--299)
       III  International Fishing and Related Activities (Parts 
                300--399)

[[Page 704]]

        IV  Joint Regulations (United States Fish and Wildlife 
                Service, Department of the Interior and National 
                Marine Fisheries Service, National Oceanic and 
                Atmospheric Administration, Department of 
                Commerce); Endangered Species Committee 
                Regulations (Parts 400--499)
         V  Marine Mammal Commission (Parts 500--599)
        VI  Fishery Conservation and Management, National Oceanic 
                and Atmospheric Administration, Department of 
                Commerce (Parts 600--699)

[[Page 705]]





           Alphabetical List of Agencies Appearing in the CFR




                      (Revised as of July 1, 2021)

                                                  CFR Title, Subtitle or 
                     Agency                               Chapter

Administrative Conference of the United States    1, III
Advisory Council on Historic Preservation         36, VIII
Advocacy and Outreach, Office of                  7, XXV
Afghanistan Reconstruction, Special Inspector     5, LXXXIII
     General for
African Development Foundation                    22, XV
  Federal Acquisition Regulation                  48, 57
Agency for International Development              2, VII; 22, II
  Federal Acquisition Regulation                  48, 7
Agricultural Marketing Service                    7, I, VIII, IX, X, XI; 9, 
                                                  II
Agricultural Research Service                     7, V
Agriculture, Department of                        2, IV; 5, LXXIII
  Advocacy and Outreach, Office of                7, XXV
  Agricultural Marketing Service                  7, I, VIII, IX, X, XI; 9, 
                                                  II
  Agricultural Research Service                   7, V
  Animal and Plant Health Inspection Service      7, III; 9, I
  Chief Financial Officer, Office of              7, XXX
  Commodity Credit Corporation                    7, XIV
  Economic Research Service                       7, XXXVII
  Energy Policy and New Uses, Office of           2, IX; 7, XXIX
  Environmental Quality, Office of                7, XXXI
  Farm Service Agency                             7, VII, XVIII
  Federal Acquisition Regulation                  48, 4
  Federal Crop Insurance Corporation              7, IV
  Food and Nutrition Service                      7, II
  Food Safety and Inspection Service              9, III
  Foreign Agricultural Service                    7, XV
  Forest Service                                  36, II
  Information Resources Management, Office of     7, XXVII
  Inspector General, Office of                    7, XXVI
  National Agricultural Library                   7, XLI
  National Agricultural Statistics Service        7, XXXVI
  National Institute of Food and Agriculture      7, XXXIV
  Natural Resources Conservation Service          7, VI
  Operations, Office of                           7, XXVIII
  Procurement and Property Management, Office of  7, XXXII
  Rural Business-Cooperative Service              7, XVIII, XLII
  Rural Development Administration                7, XLII
  Rural Housing Service                           7, XVIII, XXXV
  Rural Utilities Service                         7, XVII, XVIII, XLII
  Secretary of Agriculture, Office of             7, Subtitle A
  Transportation, Office of                       7, XXXIII
  World Agricultural Outlook Board                7, XXXVIII
Air Force, Department of                          32, VII
  Federal Acquisition Regulation Supplement       48, 53
Air Transportation Stabilization Board            14, VI
Alcohol and Tobacco Tax and Trade Bureau          27, I
Alcohol, Tobacco, Firearms, and Explosives,       27, II
     Bureau of
AMTRAK                                            49, VII
American Battle Monuments Commission              36, IV
American Indians, Office of the Special Trustee   25, VII
Animal and Plant Health Inspection Service        7, III; 9, I
Appalachian Regional Commission                   5, IX
Architectural and Transportation Barriers         36, XI
   Compliance Board
[[Page 706]]

Arctic Research Commission                        45, XXIII
Armed Forces Retirement Home                      5, XI; 38, II
Army, Department of                               32, V
  Engineers, Corps of                             33, II; 36, III
  Federal Acquisition Regulation                  48, 51
Benefits Review Board                             20, VII
Bilingual Education and Minority Languages        34, V
     Affairs, Office of
Blind or Severely Disabled, Committee for         41, 51
     Purchase from People Who Are
  Federal Acquisition Regulation                  48, 19
Career, Technical, and Adult Education, Office    34, IV
     of
Census Bureau                                     15, I
Centers for Medicare & Medicaid Services          42, IV
Central Intelligence Agency                       32, XIX
Chemical Safety and Hazard Investigation Board    40, VI
Chief Financial Officer, Office of                7, XXX
Child Support Enforcement, Office of              45, III
Children and Families, Administration for         45, II, III, IV, X, XIII
Civil Rights, Commission on                       5, LXVIII; 45, VII
Civil Rights, Office for                          34, I
Coast Guard                                       33, I; 46, I; 49, IV
Coast Guard (Great Lakes Pilotage)                46, III
Commerce, Department of                           2, XIII; 44, IV; 50, VI
  Census Bureau                                   15, I
  Economic Affairs, Office of the Under-          15, XV
       Secretary for
  Economic Analysis, Bureau of                    15, VIII
  Economic Development Administration             13, III
  Emergency Management and Assistance             44, IV
  Federal Acquisition Regulation                  48, 13
  Foreign-Trade Zones Board                       15, IV
  Industry and Security, Bureau of                15, VII
  International Trade Administration              15, III; 19, III
  National Institute of Standards and Technology  15, II; 37, IV
  National Marine Fisheries Service               50, II, IV
  National Oceanic and Atmospheric                15, IX; 50, II, III, IV, 
       Administration                             VI
  National Technical Information Service          15, XI
  National Telecommunications and Information     15, XXIII; 47, III, IV
       Administration
  National Weather Service                        15, IX
  Patent and Trademark Office, United States      37, I
  Secretary of Commerce, Office of                15, Subtitle A
Commercial Space Transportation                   14, III
Commodity Credit Corporation                      7, XIV
Commodity Futures Trading Commission              5, XLI; 17, I
Community Planning and Development, Office of     24, V, VI
     Assistant Secretary for
Community Services, Office of                     45, X
Comptroller of the Currency                       12, I
Construction Industry Collective Bargaining       29, IX
     Commission
Consumer Financial Protection Bureau              5, LXXXIV; 12, X
Consumer Product Safety Commission                5, LXXI; 16, II
Copyright Royalty Board                           37, III
Corporation for National and Community Service    2, XXII; 45, XII, XXV
Cost Accounting Standards Board                   48, 99
Council on Environmental Quality                  40, V
Council of the Inspectors General on Integrity    5, XCVIII
     and Efficiency
Court Services and Offender Supervision Agency    5, LXX; 28, VIII
     for the District of Columbia
Customs and Border Protection                     19, I
Defense, Department of                            2, XI; 5, XXVI; 32, 
                                                  Subtitle A; 40, VII
  Advanced Research Projects Agency               32, I
  Air Force Department                            32, VII
  Army Department                                 32, V; 33, II; 36, III; 
                                                  48, 51
  Defense Acquisition Regulations System          48, 2
  Defense Intelligence Agency                     32, I

[[Page 707]]

  Defense Logistics Agency                        32, I, XII; 48, 54
  Engineers, Corps of                             33, II; 36, III
  National Imagery and Mapping Agency             32, I
  Navy, Department of                             32, VI; 48, 52
  Secretary of Defense, Office of                 2, XI; 32, I
Defense Contract Audit Agency                     32, I
Defense Intelligence Agency                       32, I
Defense Logistics Agency                          32, XII; 48, 54
Defense Nuclear Facilities Safety Board           10, XVII
Delaware River Basin Commission                   18, III
Denali Commission                                 45, IX
Disability, National Council on                   5, C; 34, XII
District of Columbia, Court Services and          5, LXX; 28, VIII
     Offender Supervision Agency for the
Drug Enforcement Administration                   21, II
East-West Foreign Trade Board                     15, XIII
Economic Affairs, Office of the Under-Secretary   15, XV
     for
Economic Analysis, Bureau of                      15, VIII
Economic Development Administration               13, III
Economic Research Service                         7, XXXVII
Education, Department of                          2, XXXIV; 5, LIII
  Bilingual Education and Minority Languages      34, V
       Affairs, Office of
  Career, Technical, and Adult Education, Office  34, IV
       of
  Civil Rights, Office for                        34, I
  Educational Research and Improvement, Office    34, VII
       of
  Elementary and Secondary Education, Office of   34, II
  Federal Acquisition Regulation                  48, 34
  Postsecondary Education, Office of              34, VI
  Secretary of Education, Office of               34, Subtitle A
  Special Education and Rehabilitative Services,  34, III
       Office of
Educational Research and Improvement, Office of   34, VII
Election Assistance Commission                    2, LVIII; 11, II
Elementary and Secondary Education, Office of     34, II
Emergency Oil and Gas Guaranteed Loan Board       13, V
Emergency Steel Guarantee Loan Board              13, IV
Employee Benefits Security Administration         29, XXV
Employees' Compensation Appeals Board             20, IV
Employees Loyalty Board                           5, V
Employment and Training Administration            20, V
Employment Policy, National Commission for        1, IV
Employment Standards Administration               20, VI
Endangered Species Committee                      50, IV
Energy, Department of                             2, IX; 5, XXIII; 10, II, 
                                                  III, X
  Federal Acquisition Regulation                  48, 9
  Federal Energy Regulatory Commission            5, XXIV; 18, I
  Property Management Regulations                 41, 109
Energy, Office of                                 7, XXIX
Engineers, Corps of                               33, II; 36, III
Engraving and Printing, Bureau of                 31, VI
Environmental Protection Agency                   2, XV; 5, LIV; 40, I, IV, 
                                                  VII
  Federal Acquisition Regulation                  48, 15
  Property Management Regulations                 41, 115
Environmental Quality, Office of                  7, XXXI
Equal Employment Opportunity Commission           5, LXII; 29, XIV
Equal Opportunity, Office of Assistant Secretary  24, I
     for
Executive Office of the President                 3, I
  Environmental Quality, Council on               40, V
  Management and Budget, Office of                2, Subtitle A; 5, III, 
                                                  LXXVII; 14, VI; 48, 99
  National Drug Control Policy, Office of         2, XXXVI; 21, III
  National Security Council                       32, XXI; 47, II
  Presidential Documents                          3
  Science and Technology Policy, Office of        32, XXIV; 47, II
  Trade Representative, Office of the United      15, XX
     States
[[Page 708]]

Export-Import Bank of the United States           2, XXXV; 5, LII; 12, IV
Family Assistance, Office of                      45, II
Farm Credit Administration                        5, XXXI; 12, VI
Farm Credit System Insurance Corporation          5, XXX; 12, XIV
Farm Service Agency                               7, VII, XVIII
Federal Acquisition Regulation                    48, 1
Federal Aviation Administration                   14, I
  Commercial Space Transportation                 14, III
Federal Claims Collection Standards               31, IX
Federal Communications Commission                 5, XXIX; 47, I
Federal Contract Compliance Programs, Office of   41, 60
Federal Crop Insurance Corporation                7, IV
Federal Deposit Insurance Corporation             5, XXII; 12, III
Federal Election Commission                       5, XXXVII; 11, I
Federal Emergency Management Agency               44, I
Federal Employees Group Life Insurance Federal    48, 21
     Acquisition Regulation
Federal Employees Health Benefits Acquisition     48, 16
     Regulation
Federal Energy Regulatory Commission              5, XXIV; 18, I
Federal Financial Institutions Examination        12, XI
     Council
Federal Financing Bank                            12, VIII
Federal Highway Administration                    23, I, II
Federal Home Loan Mortgage Corporation            1, IV
Federal Housing Enterprise Oversight Office       12, XVII
Federal Housing Finance Agency                    5, LXXX; 12, XII
Federal Labor Relations Authority                 5, XIV, XLIX; 22, XIV
Federal Law Enforcement Training Center           31, VII
Federal Management Regulation                     41, 102
Federal Maritime Commission                       46, IV
Federal Mediation and Conciliation Service        29, XII
Federal Mine Safety and Health Review Commission  5, LXXIV; 29, XXVII
Federal Motor Carrier Safety Administration       49, III
Federal Permitting Improvement Steering Council   40, IX
Federal Prison Industries, Inc.                   28, III
Federal Procurement Policy Office                 48, 99
Federal Property Management Regulations           41, 101
Federal Railroad Administration                   49, II
Federal Register, Administrative Committee of     1, I
Federal Register, Office of                       1, II
Federal Reserve System                            12, II
  Board of Governors                              5, LVIII
Federal Retirement Thrift Investment Board        5, VI, LXXVI
Federal Service Impasses Panel                    5, XIV
Federal Trade Commission                          5, XLVII; 16, I
Federal Transit Administration                    49, VI
Federal Travel Regulation System                  41, Subtitle F
Financial Crimes Enforcement Network              31, X
Financial Research Office                         12, XVI
Financial Stability Oversight Council             12, XIII
Fine Arts, Commission of                          45, XXI
Fiscal Service                                    31, II
Fish and Wildlife Service, United States          50, I, IV
Food and Drug Administration                      21, I
Food and Nutrition Service                        7, II
Food Safety and Inspection Service                9, III
Foreign Agricultural Service                      7, XV
Foreign Assets Control, Office of                 31, V
Foreign Claims Settlement Commission of the       45, V
     United States
Foreign Service Grievance Board                   22, IX
Foreign Service Impasse Disputes Panel            22, XIV
Foreign Service Labor Relations Board             22, XIV
Foreign-Trade Zones Board                         15, IV
Forest Service                                    36, II
General Services Administration                   5, LVII; 41, 105
  Contract Appeals, Board of                      48, 61
  Federal Acquisition Regulation                  48, 5
  Federal Management Regulation                   41, 102

[[Page 709]]

  Federal Property Management Regulations         41, 101
  Federal Travel Regulation System                41, Subtitle F
  General                                         41, 300
  Payment From a Non-Federal Source for Travel    41, 304
       Expenses
  Payment of Expenses Connected With the Death    41, 303
       of Certain Employees
  Relocation Allowances                           41, 302
  Temporary Duty (TDY) Travel Allowances          41, 301
Geological Survey                                 30, IV
Government Accountability Office                  4, I
Government Ethics, Office of                      5, XVI
Government National Mortgage Association          24, III
Grain Inspection, Packers and Stockyards          7, VIII; 9, II
     Administration
Great Lakes St. Lawrence Seaway Development       33, IV
     Corporation
Gulf Coast Ecosystem Restoration Council          2, LIX; 40, VIII
Harry S. Truman Scholarship Foundation            45, XVIII
Health and Human Services, Department of          2, III; 5, XLV; 45, 
                                                  Subtitle A
  Centers for Medicare & Medicaid Services        42, IV
  Child Support Enforcement, Office of            45, III
  Children and Families, Administration for       45, II, III, IV, X, XIII
  Community Services, Office of                   45, X
  Family Assistance, Office of                    45, II
  Federal Acquisition Regulation                  48, 3
  Food and Drug Administration                    21, I
  Indian Health Service                           25, V
  Inspector General (Health Care), Office of      42, V
  Public Health Service                           42, I
  Refugee Resettlement, Office of                 45, IV
Homeland Security, Department of                  2, XXX; 5, XXXVI; 6, I; 8, 
                                                  I
  Coast Guard                                     33, I; 46, I; 49, IV
  Coast Guard (Great Lakes Pilotage)              46, III
  Customs and Border Protection                   19, I
  Federal Emergency Management Agency             44, I
  Human Resources Management and Labor Relations  5, XCVII
       Systems
  Immigration and Customs Enforcement Bureau      19, IV
  Transportation Security Administration          49, XII
HOPE for Homeowners Program, Board of Directors   24, XXIV
     of
Housing, Office of, and Multifamily Housing       24, IV
     Assistance Restructuring, Office of
Housing and Urban Development, Department of      2, XXIV; 5, LXV; 24, 
                                                  Subtitle B
  Community Planning and Development, Office of   24, V, VI
       Assistant Secretary for
  Equal Opportunity, Office of Assistant          24, I
       Secretary for
  Federal Acquisition Regulation                  48, 24
  Federal Housing Enterprise Oversight, Office    12, XVII
       of
  Government National Mortgage Association        24, III
  Housing--Federal Housing Commissioner, Office   24, II, VIII, X, XX
       of Assistant Secretary for
  Housing, Office of, and Multifamily Housing     24, IV
       Assistance Restructuring, Office of
  Inspector General, Office of                    24, XII
  Public and Indian Housing, Office of Assistant  24, IX
       Secretary for
  Secretary, Office of                            24, Subtitle A, VII
Housing--Federal Housing Commissioner, Office of  24, II, VIII, X, XX
     Assistant Secretary for
Housing, Office of, and Multifamily Housing       24, IV
     Assistance Restructuring, Office of
Immigration and Customs Enforcement Bureau        19, IV
Immigration Review, Executive Office for          8, V
Independent Counsel, Office of                    28, VII
Independent Counsel, Offices of                   28, VI
Indian Affairs, Bureau of                         25, I, V
Indian Affairs, Office of the Assistant           25, VI
   Secretary
[[Page 710]]

Indian Arts and Crafts Board                      25, II
Indian Health Service                             25, V
Industry and Security, Bureau of                  15, VII
Information Resources Management, Office of       7, XXVII
Information Security Oversight Office, National   32, XX
     Archives and Records Administration
Inspector General
  Agriculture Department                          7, XXVI
  Health and Human Services Department            42, V
  Housing and Urban Development Department        24, XII, XV
Institute of Peace, United States                 22, XVII
Inter-American Foundation                         5, LXIII; 22, X
Interior, Department of                           2, XIV
  American Indians, Office of the Special         25, VII
       Trustee
  Endangered Species Committee                    50, IV
  Federal Acquisition Regulation                  48, 14
  Federal Property Management Regulations System  41, 114
  Fish and Wildlife Service, United States        50, I, IV
  Geological Survey                               30, IV
  Indian Affairs, Bureau of                       25, I, V
  Indian Affairs, Office of the Assistant         25, VI
       Secretary
  Indian Arts and Crafts Board                    25, II
  Land Management, Bureau of                      43, II
  National Indian Gaming Commission               25, III
  National Park Service                           36, I
  Natural Resource Revenue, Office of             30, XII
  Ocean Energy Management, Bureau of              30, V
  Reclamation, Bureau of                          43, I
  Safety and Environmental Enforcement, Bureau    30, II
       of
  Secretary of the Interior, Office of            2, XIV; 43, Subtitle A
  Surface Mining Reclamation and Enforcement,     30, VII
       Office of
Internal Revenue Service                          26, I
International Boundary and Water Commission,      22, XI
     United States and Mexico, United States 
     Section
International Development, United States Agency   22, II
     for
  Federal Acquisition Regulation                  48, 7
International Development Cooperation Agency,     22, XII
     United States
International Development Finance Corporation,    5, XXXIII; 22, VII
     U.S.
International Joint Commission, United States     22, IV
     and Canada
International Organizations Employees Loyalty     5, V
     Board
International Trade Administration                15, III; 19, III
International Trade Commission, United States     19, II
Interstate Commerce Commission                    5, XL
Investment Security, Office of                    31, VIII
James Madison Memorial Fellowship Foundation      45, XXIV
Japan-United States Friendship Commission         22, XVI
Joint Board for the Enrollment of Actuaries       20, VIII
Justice, Department of                            2, XXVIII; 5, XXVIII; 28, 
                                                  I, XI; 40, IV
  Alcohol, Tobacco, Firearms, and Explosives,     27, II
       Bureau of
  Drug Enforcement Administration                 21, II
  Federal Acquisition Regulation                  48, 28
  Federal Claims Collection Standards             31, IX
  Federal Prison Industries, Inc.                 28, III
  Foreign Claims Settlement Commission of the     45, V
       United States
  Immigration Review, Executive Office for        8, V
  Independent Counsel, Offices of                 28, VI
  Prisons, Bureau of                              28, V
  Property Management Regulations                 41, 128
Labor, Department of                              2, XXIX; 5, XLII
  Benefits Review Board                           20, VII
  Employee Benefits Security Administration       29, XXV
  Employees' Compensation Appeals Board           20, IV
  Employment and Training Administration          20, V
  Federal Acquisition Regulation                  48, 29

[[Page 711]]

  Federal Contract Compliance Programs, Office    41, 60
       of
  Federal Procurement Regulations System          41, 50
  Labor-Management Standards, Office of           29, II, IV
  Mine Safety and Health Administration           30, I
  Occupational Safety and Health Administration   29, XVII
  Public Contracts                                41, 50
  Secretary of Labor, Office of                   29, Subtitle A
  Veterans' Employment and Training Service,      41, 61; 20, IX
       Office of the Assistant Secretary for
  Wage and Hour Division                          29, V
  Workers' Compensation Programs, Office of       20, I, VI
Labor-Management Standards, Office of             29, II, IV
Land Management, Bureau of                        43, II
Legal Services Corporation                        45, XVI
Libraries and Information Science, National       45, XVII
     Commission on
Library of Congress                               36, VII
  Copyright Royalty Board                         37, III
  U.S. Copyright Office                           37, II
Management and Budget, Office of                  5, III, LXXVII; 14, VI; 
                                                  48, 99
Marine Mammal Commission                          50, V
Maritime Administration                           46, II
Merit Systems Protection Board                    5, II, LXIV
Micronesian Status Negotiations, Office for       32, XXVII
Military Compensation and Retirement              5, XCIX
     Modernization Commission
Millennium Challenge Corporation                  22, XIII
Mine Safety and Health Administration             30, I
Minority Business Development Agency              15, XIV
Miscellaneous Agencies                            1, IV
Monetary Offices                                  31, I
Morris K. Udall Scholarship and Excellence in     36, XVI
     National Environmental Policy Foundation
Museum and Library Services, Institute of         2, XXXI
National Aeronautics and Space Administration     2, XVIII; 5, LIX; 14, V
  Federal Acquisition Regulation                  48, 18
National Agricultural Library                     7, XLI
National Agricultural Statistics Service          7, XXXVI
National and Community Service, Corporation for   2, XXII; 45, XII, XXV
National Archives and Records Administration      2, XXVI; 5, LXVI; 36, XII
  Information Security Oversight Office           32, XX
National Capital Planning Commission              1, IV, VI
National Counterintelligence Center               32, XVIII
National Credit Union Administration              5, LXXXVI; 12, VII
National Crime Prevention and Privacy Compact     28, IX
     Council
National Drug Control Policy, Office of           2, XXXVI; 21, III
National Endowment for the Arts                   2, XXXII
National Endowment for the Humanities             2, XXXIII
National Foundation on the Arts and the           45, XI
     Humanities
National Geospatial-Intelligence Agency           32, I
National Highway Traffic Safety Administration    23, II, III; 47, VI; 49, V
National Imagery and Mapping Agency               32, I
National Indian Gaming Commission                 25, III
National Institute of Food and Agriculture        7, XXXIV
National Institute of Standards and Technology    15, II; 37, IV
National Intelligence, Office of Director of      5, IV; 32, XVII
National Labor Relations Board                    5, LXI; 29, I
National Marine Fisheries Service                 50, II, IV
National Mediation Board                          5, CI; 29, X
National Oceanic and Atmospheric Administration   15, IX; 50, II, III, IV, 
                                                  VI
National Park Service                             36, I
National Railroad Adjustment Board                29, III
National Railroad Passenger Corporation (AMTRAK)  49, VII
National Science Foundation                       2, XXV; 5, XLIII; 45, VI
  Federal Acquisition Regulation                  48, 25
National Security Council                         32, XXI; 47, II

[[Page 712]]

National Technical Information Service            15, XI
National Telecommunications and Information       15, XXIII; 47, III, IV, V
     Administration
National Transportation Safety Board              49, VIII
Natural Resource Revenue, Office of               30, XII
Natural Resources Conservation Service            7, VI
Navajo and Hopi Indian Relocation, Office of      25, IV
Navy, Department of                               32, VI
  Federal Acquisition Regulation                  48, 52
Neighborhood Reinvestment Corporation             24, XXV
Northeast Interstate Low-Level Radioactive Waste  10, XVIII
     Commission
Nuclear Regulatory Commission                     2, XX; 5, XLVIII; 10, I
  Federal Acquisition Regulation                  48, 20
Occupational Safety and Health Administration     29, XVII
Occupational Safety and Health Review Commission  29, XX
Ocean Energy Management, Bureau of                30, V
Oklahoma City National Memorial Trust             36, XV
Operations Office                                 7, XXVIII
Patent and Trademark Office, United States        37, I
Payment From a Non-Federal Source for Travel      41, 304
     Expenses
Payment of Expenses Connected With the Death of   41, 303
     Certain Employees
Peace Corps                                       2, XXXVII; 22, III
Pennsylvania Avenue Development Corporation       36, IX
Pension Benefit Guaranty Corporation              29, XL
Personnel Management, Office of                   5, I, IV, XXXV; 45, VIII
  Federal Acquisition Regulation                  48, 17
  Federal Employees Group Life Insurance Federal  48, 21
       Acquisition Regulation
  Federal Employees Health Benefits Acquisition   48, 16
       Regulation
  Human Resources Management and Labor Relations  5, XCVII
       Systems, Department of Homeland Security
Pipeline and Hazardous Materials Safety           49, I
     Administration
Postal Regulatory Commission                      5, XLVI; 39, III
Postal Service, United States                     5, LX; 39, I
Postsecondary Education, Office of                34, VI
President's Commission on White House             1, IV
     Fellowships
Presidential Documents                            3
Presidio Trust                                    36, X
Prisons, Bureau of                                28, V
Privacy and Civil Liberties Oversight Board       6, X
Procurement and Property Management, Office of    7, XXXII
Public and Indian Housing, Office of Assistant    24, IX
     Secretary for
Public Contracts, Department of Labor             41, 50
Public Health Service                             42, I
Railroad Retirement Board                         20, II
Reclamation, Bureau of                            43, I
Refugee Resettlement, Office of                   45, IV
Relocation Allowances                             41, 302
Research and Innovative Technology                49, XI
     Administration
Rural Business-Cooperative Service                7, XVIII, XLII
Rural Development Administration                  7, XLII
Rural Housing Service                             7, XVIII, XXXV
Rural Utilities Service                           7, XVII, XVIII, XLII
Safety and Environmental Enforcement, Bureau of   30, II
Science and Technology Policy, Office of, and     32, XXIV; 47, II
     National Security Council
Secret Service                                    31, IV
Securities and Exchange Commission                5, XXXIV; 17, II
Selective Service System                          32, XVI
Small Business Administration                     2, XXVII; 13, I
Smithsonian Institution                           36, V
Social Security Administration                    2, XXIII; 20, III; 48, 23
Soldiers' and Airmen's Home, United States        5, XI
Special Counsel, Office of                        5, VIII
Special Education and Rehabilitative Services,    34, III
   Office of
[[Page 713]]

State, Department of                              2, VI; 22, I; 28, XI
  Federal Acquisition Regulation                  48, 6
Surface Mining Reclamation and Enforcement,       30, VII
     Office of
Surface Transportation Board                      49, X
Susquehanna River Basin Commission                18, VIII
Tennessee Valley Authority                        5, LXIX; 18, XIII
Trade Representative, United States, Office of    15, XX
Transportation, Department of                     2, XII; 5, L
  Commercial Space Transportation                 14, III
  Emergency Management and Assistance             44, IV
  Federal Acquisition Regulation                  48, 12
  Federal Aviation Administration                 14, I
  Federal Highway Administration                  23, I, II
  Federal Motor Carrier Safety Administration     49, III
  Federal Railroad Administration                 49, II
  Federal Transit Administration                  49, VI
  Great Lakes St. Lawrence Seaway Development     33, IV
       Corporation
  Maritime Administration                         46, II
  National Highway Traffic Safety Administration  23, II, III; 47, IV; 49, V
  Pipeline and Hazardous Materials Safety         49, I
       Administration
  Secretary of Transportation, Office of          14, II; 49, Subtitle A
  Transportation Statistics Bureau                49, XI
Transportation, Office of                         7, XXXIII
Transportation Security Administration            49, XII
Transportation Statistics Bureau                  49, XI
Travel Allowances, Temporary Duty (TDY)           41, 301
Treasury, Department of the                       2, X; 5, XXI; 12, XV; 17, 
                                                  IV; 31, IX
  Alcohol and Tobacco Tax and Trade Bureau        27, I
  Community Development Financial Institutions    12, XVIII
       Fund
  Comptroller of the Currency                     12, I
  Customs and Border Protection                   19, I
  Engraving and Printing, Bureau of               31, VI
  Federal Acquisition Regulation                  48, 10
  Federal Claims Collection Standards             31, IX
  Federal Law Enforcement Training Center         31, VII
  Financial Crimes Enforcement Network            31, X
  Fiscal Service                                  31, II
  Foreign Assets Control, Office of               31, V
  Internal Revenue Service                        26, I
  Investment Security, Office of                  31, VIII
  Monetary Offices                                31, I
  Secret Service                                  31, IV
  Secretary of the Treasury, Office of            31, Subtitle A
Truman, Harry S. Scholarship Foundation           45, XVIII
United States Agency for Global Media             22, V
United States and Canada, International Joint     22, IV
     Commission
United States and Mexico, International Boundary  22, XI
     and Water Commission, United States Section
U.S. Copyright Office                             37, II
U.S. Office of Special Counsel                    5, CII
Utah Reclamation Mitigation and Conservation      43, III
     Commission
Veterans Affairs, Department of                   2, VIII; 38, I
  Federal Acquisition Regulation                  48, 8
Veterans' Employment and Training Service,        41, 61; 20, IX
     Office of the Assistant Secretary for
Vice President of the United States, Office of    32, XXVIII
Wage and Hour Division                            29, V
Water Resources Council                           18, VI
Workers' Compensation Programs, Office of         20, I, VII
World Agricultural Outlook Board                  7, XXXVIII

[[Page 715]]



List of CFR Sections Affected



All changes in this volume of the Code of Federal Regulations (CFR) that 
were made by documents published in the Federal Register since January 
1, 2016 are enumerated in the following list. Entries indicate the 
nature of the changes effected. Page numbers refer to Federal Register 
pages. The user should consult the entries for chapters, parts and 
subparts as well as sections for revisions.
For changes to this volume of the CFR prior to this listing, consult the 
annual edition of the monthly List of CFR Sections Affected (LSA). The 
LSA is available at www.govinfo.gov. For changes to this volume of the 
CFR prior to 2001, see the ``List of CFR Sections Affected, 1949-1963, 
1964-1972, 1973-1985, and 1986-2000'' published in 11 separate volumes. 
The ``List of CFR Sections Affected 1986-2000'' is available at 
www.govinfo.gov.

                                  2016

40 CFR
                                                                   81 FR
                                                                    Page
Chapter I
50 Policy statement................................................71906
50.1 (j) and (k) revised; (m) through (r) added....................68276
50.13 (d) added....................................................58149
50.14 Revised......................................................68277
50 Appendix N amended..............................................53008
    Regulation at 81 FR 53008 withdrawn............................66823
51.1--51.50 (Subpart A) Appendix A amended.........................58149
51.100 (s)(1) introductory text revised; (s)(5) removed.............9342
    (s)(1) introductory text revised...............................50335
51.121 Regulation at 79 FR 71671 confirmed.........................13279
51.123 Regulation at 79 FR 71671 confirmed.........................13279
51.124 Regulation at 79 FR 71671 confirmed.........................13279
51.161 (b)(1) revised..............................................71629
51.165 (a)(1)(ii) revised; eff. 8-2-16.............................35632
    (a)(1)(iv)(A)(1), (x)(A), (xxxvii)(C)(2), (2)(i) and (ii)(A) 
revised; (a)(1)(x)(F) and (13) added; (a)(1)(xxxvii)(C)(3), (4) 
removed............................................................58150
    (i) added......................................................71629
51.166 (b)(6) revised; eff. 8-2-16.................................35632
    (q)(2)(ii), (iii), (vi) and (viii) revised.....................71629
51.930 Revised.....................................................68282
51.1000--51.1016 (Subpart Z) Revised...............................58151
51 Appendix S amended; eff. 8-2-16.................................35633
    Amended........................................................58161
    Appendix M amended.............................................59806
    Appendix P amended.............................................59808

                                  2017

40 CFR
                                                                   82 FR
                                                                    Page
Chapter I
50 Appendix N amended..............................................14327
51.300 (b) revised..................................................3122
51.301 Amended......................................................3122
51.302 Revised......................................................3123
51.303 (a)(1) revised...............................................3123
51.304 Revised......................................................3123
51.305 Revised......................................................3124
51.306 Removed......................................................3124
51.307 (a) introductory text, (b)(1) and (2) revised................3124
51.308 (b), (d)(2)(iv), (3) introductory text, (e)(2)(v), (4), 
        (5), (f), (g) introductory text, (3) through (7), (h) 
        introductory text, (1), (i)(2) introductory text, (ii), 
        (3) and (4) revised; (g)(8) added...........................3124

[[Page 716]]

51.309 (b)(4), (d)(4)(v), (10) introductory text, (i) introductory 
        text, (ii) introductory text and (g)(2)(iii) revised; 
        (b)(8) removed; (d)(10)(iii) and (iv) added.................3128
51 Appendix W revised...............................................5203
    Regulation at 82 FR 5203 eff. date delayed to 3-21-17...........8499
    Regulation at 82 FR 5203 eff. date further delayed to 5-22-17 
                                                                   14324

                                  2018

40 CFR
                                                                   83 FR
                                                                    Page
Chapter I
50 National ambient air quality standards..........................17226
51 Regulation at 74 FR 2376 confirmed; stay lifted.................57324
51.1--51.50 (Subpart A) Appendix A amended.........................63031
51.100 (s)(1) introductory text revised............................61134
51.165 (a)(11) revised.............................................63032
51.1300--51.1303 (Subpart CC) Added................................10382
51.1300 (f) through (q) added......................................63032
51.1304............................................................63033
51.1305............................................................63033
51.1306............................................................63033
51.1307............................................................63033
51.1308............................................................63033
51.1309............................................................63034
51.1310............................................................63034
51.1311............................................................63035
51.1312............................................................63035
51.1313............................................................63035
51.1314............................................................63035
51.1315............................................................63035
51.1316............................................................63036
51.1317............................................................63036
51.1318............................................................63036
51.1319............................................................63036
51 Appendix M amended; CFR correction..............................12260
    Appendix M amended.............................................56720
    Appendix S amended.............................................63036

                                  2019

40 CFR
                                                                   84 FR
                                                                    Page
Chapter I
50 National ambient air quality standards...........................9865
51.121 Heading, (a)(3), (d)(2), (e)(2)(i), (i)(4), (5), and (r) 
        revised; (b)(1) introductory text, (i), (ii), (iii), 
        (c)(1), (2), (e)(1), (2)(ii)(A), (B), (E), (f) 
        introductory text, (2), (i)(B), (C), (ii), (g)(1), (2)(i), 
        (iii), (h), (i) introductory text, (2), (3), (j)(1), 
        (k)(2), and (l) through (o) amended; (a)(2), (b)(2), 
        (d)(1), (e)(3), (4), (5), (g)(2)(ii), (p), and (q) removed
                                                                    8442
51.122 (c)(1)(ii), (e), and (f) amended; second (g) removed.........8443

                                  2020

40 CFR
                                                                   85 FR
                                                                    Page
Chapter I
50 National ambient air quality standards...................82683, 87255
51.165 (a)(2)(ii)(F) revised; (a)(2)(ii)(G) added..................74908
51.166 (a)(7)(iv)(f) revised; (a)(7)(iv)(g) added..................74908
51 Appendix M amended..............................................63401
51 Appendix P amended..............................................49600
51 Appendix S amended..............................................74908

                                  2021

   (Regulations published from January 1, 2021, through July 1, 2021)

40 CFR
                                                                   86 FR
                                                                    Page
Chapter I
51 State implementation plan determinations........................28710
51 Technical correction............................................29949
51.121 (r)(2) amended..............................................23164


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