[Title 40 CFR ]
[Code of Federal Regulations (annual edition) - July 1, 1999 Edition]
[From the U.S. Government Printing Office]


          40



          Protection of Environment



[[Page i]]

          PARTS 50 TO 51

                         Revised as of July 1, 1999

          CONTAINING
          A CODIFICATION OF DOCUMENTS
          OF GENERAL APPLICABILITY
          AND FUTURE EFFECT

          AS OF JULY 1, 1999
          With Ancillaries
          Published by
          the Office of the Federal Register
          National Archives and Records
          Administration

          as a Special Edition of
          the Federal Register



[[Page ii]]






                     U.S. GOVERNMENT PRINTING OFFICE
                            WASHINGTON : 1999



               For sale by U.S. Government Printing Office
 Superintendent of Documents, Mail Stop: SSOP, Washington, DC 20402-9328



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                            Table of Contents



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

  Title 40:

          Chapter I--Environmental Protection Agency..........       3

  Finding Aids:

      Material Incorporated by Reference......................     487

      Table of CFR Titles and Chapters........................     489

      Alphabetical List of Agencies Appearing in the CFR......     507

      List of CFR Sections Affected...........................     517



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

                     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.

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

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                               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 
issues of the Federal Register. These two publications must be used 
together to determine the latest version of any given rule.
    To determine whether a Code volume has been amended since its 
revision date (in this case, July 1, 1999), consult the ``List of CFR 
Sections Affected (LSA),'' which is issued monthly, and the ``Cumulative 
List of Parts Affected,'' which appears in the Reader Aids section of 
the daily Federal Register. These two lists will identify the Federal 
Register page number of the latest amendment of any given rule.

EFFECTIVE AND EXPIRATION DATES

    Each volume of the Code contains amendments published in the Federal 
Register since the last revision of that volume of the Code. Source 
citations for the regulations are referred to by volume number and page 
number of the Federal Register and date of publication. Publication 
dates and effective dates are usually not the same and care must be 
exercised by the user in determining the actual effective date. In 
instances where the effective date is beyond the cut-off date for the 
Code a note has been inserted to reflect the future effective date. In 
those instances where a regulation published in the Federal Register 
states a date certain for expiration, an appropriate note will be 
inserted following the text.

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 
amendments to existing regulations in the CFR. These OMB numbers are 
placed as close as possible to the applicable recordkeeping or reporting 
requirements.

OBSOLETE PROVISIONS

    Provisions that become obsolete before the revision date stated on 
the cover of each volume are not carried. Code users may find the text 
of provisions in effect on a given date in the past by using the 
appropriate numerical list of sections affected. For the period before 
January 1, 1986, consult either the List of CFR Sections Affected, 1949-
1963, 1964-1972, or 1973-1985, published in seven separate volumes. For 
the period beginning January 1, 1986, a ``List of CFR Sections 
Affected'' is published at the end of each CFR volume.

INCORPORATION BY REFERENCE

    What is incorporation by reference? Incorporation by reference was 
established by statute and allows Federal agencies to meet the 
requirement to publish regulations in the Federal Register by referring 
to materials already published elsewhere. For an incorporation to be 
valid, the Director of the Federal Register must approve it. The legal 
effect of incorporation by reference is that the material is treated as 
if it were published in full in the Federal Register (5 U.S.C. 552(a)). 
This material, like any other properly issued regulation, has the force 
of law.
    What is a proper incorporation by reference? The Director of the 
Federal Register will approve an incorporation by reference only when 
the requirements of 1 CFR part 51 are met. Some of the elements on which 
approval is based are:
    (a) The incorporation will substantially reduce the volume of 
material published in the Federal Register.
    (b) The matter incorporated is in fact available to the extent 
necessary to afford fairness and uniformity in the administrative 
process.
    (c) The incorporating document is drafted and submitted for 
publication in accordance with 1 CFR part 51.
    Properly approved incorporations by reference in this volume are 
listed in the Finding Aids at the end of this volume.
    What if the material incorporated by reference cannot be found? If 
you have any problem locating or obtaining a copy of material listed in 
the Finding Aids of this volume as an approved incorporation by 
reference, please contact the agency that issued the regulation 
containing that incorporation. If, after contacting the agency, you find 
the material is not available, please notify the Director of the Federal 
Register, National Archives and Records Administration, Washington DC 
20408, or call (202) 523-4534.

CFR INDEXES AND TABULAR GUIDES

    A subject index to the Code of Federal Regulations is contained in a 
separate volume, revised annually as of January 1, entitled CFR Index 
and Finding Aids. This volume contains the Parallel Table of Statutory 
Authorities and Agency Rules (Table I). A list of CFR titles, chapters, 
and parts and an alphabetical list of agencies publishing in the CFR are 
also included in this volume.
    An index to the text of ``Title 3--The President'' is carried within 
that volume.
    The Federal Register Index is issued monthly in cumulative form. 
This index is based on a consolidation of the ``Contents'' entries in 
the daily Federal Register.
    A List of CFR Sections Affected (LSA) is published monthly, keyed to 
the revision dates of the 50 CFR titles.

[[Page vii]]


REPUBLICATION OF MATERIAL

    There are no restrictions on the republication of material appearing 
in the Code of Federal Regulations.

INQUIRIES

    For a legal interpretation or explanation of any regulation in this 
volume, contact the issuing agency. The issuing agency's name appears at 
the top of odd-numbered pages.
    For inquiries concerning CFR reference assistance, call 202-523-5227 
or write to the Director, Office of the Federal Register, National 
Archives and Records Administration, Washington, DC 20408.

SALES

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ELECTRONIC SERVICES

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    The Office of the Federal Register also offers a free service on the 
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site also contains links to GPO Access.

                              Raymond A. Mosley,
                                    Director,
                          Office of the Federal Register.

July 1, 1999.



[[Page ix]]



                               THIS TITLE

    Title 40--Protection of Environment is composed of twenty-four 
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-End), 
parts 53-59, part 60, parts 61-62, part 63 (63.1-63.1199), part 63 
(63.1200-End), parts 64-71, parts 72-80, parts 81-85, part 86, parts 87-
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 700-789, and 
part 790 to End. The contents of these volumes represent all current 
regulations codified under this title of the CFR as of July 1, 1999.

    Chapter I--Environmental Protection Agency appears in all twenty-
four volumes. A Pesticide Tolerance Commodity/Chemical Index appears in 
parts 150-189. A Toxic Substances Chemical--CAS Number Index appears in 
parts 700-789 and part 790 to End. Redesignation Tables appear in the 
volumes containing parts 50-51, parts 150-189, and parts 700-789. 
Regulations issued by the Council on Environmental Quality appear in the 
volume containing part 790 to End. The OMB control numbers for title 40 
appear in Sec. 9.1 of this chapter.

    For this volume, Linda L. Jones was Chief Editor. The Code of 
Federal Regulations publication program is under the direction of 
Frances D. McDonald, assisted by Alomha S. Morris.

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

[[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




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


  Editorial Note: Subchapter C--Air Programs is continued in volumes 40 
CFR parts 50-51, part 52 (52.01-52.1018), part 52 (52.1019-End), parts 
53-59, part 60, parts 61-62, part 63 (63.1-63.1199), part 63 (63.1200-
End), parts 64-71, parts 72-80, parts 81-85, part 86, and parts 87-135.

                       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.......         129

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                       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 
          particulate matter.
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 
          nitrogen dioxide.
50.12  National primary and secondary ambient air quality standards for 
          lead.

Appendix A 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--Measurement Principle and Calibration Procedure 
          for the Measurement of Ozone in the Atmosphere
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 
          Suspended Particulate Matter Collected From Ambient Air
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--Reference Method for the Determination of 
          Particulate Matter as PM10 in the Atmosphere
Appendix N to Part 50--Interpretation of the National Ambient Air 
          Quality Standards for Particulate Matter

    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

[[Page 6]]

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.

[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]



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 the particulate 
matter (PM10 and PM2.5) standards contained in 
Sec. 50.7 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 PM10 and PM2.5 for purposes of 
comparison to the standards contained in Sec. 50.7 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.

[62 FR 38711, July 18, 1997]



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 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

[[Page 7]]

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.

[61 FR 25579, May 22, 1996]



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 (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 g/m\3\, as determined 
in accordance with appendix K to this part, is equal to or less than 
one.
    (b) The level of the national primary and secondary annual standards 
for particulate matter is 50 micrograms per cubic meter (g/
m\3\), annual arithmetic mean. The standards are attained when the 
expected annual arithmetic mean concentration, as determined in 
accordance with appendix K to this part, is less than or equal to 50 
g/m\3\.
    (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.
    (d) The PM10 standards set forth in this section will no 
longer apply to an area not attaining these standards as of September 
16, 1997, once EPA takes final action to promulgate a rule pursuant to 
section 172(e) of the Clean Air Act, as amended (42 U.S.C. 7472(e)) 
applicable to the area. The PM10 standards set forth in this 
section will no longer apply to an area attaining these standards as of 
September 16, 1997, once EPA approves a State Implementation Plan (SIP) 
applicable to the area containing all PM10 control measures 
adopted and implemented by the State prior to September 16, 1997, and a 
section 110 SIP implementing the PM standards published on July 18, 
1997.

[[Page 8]]

SIP approvals are codified in 40 CFR part 52.

[52 FR 24663, July 1, 1987, as amended at 62 FR 38711, July 18, 1997]



Sec. 50.7   National primary and secondary ambient air quality standards for particulate matter.

    (a) The national primary and secondary ambient air quality standards 
for particulate matter are:
    (1) 15.0 micrograms per cubic meter (g/m3) 
annual arithmetic mean concentration, and 65 g/m3 
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:
    (i) A reference method based on appendix L of this part and 
designated in accordance with part 53 of this chapter; or
    (ii) An equivalent method designated in accordance with part 53 of 
this chapter.
    (2) 50 micrograms per cubic meter (g/m3) annual 
arithmetic mean concentration, and 150 g/m3 24-hour 
average concentration measured in the ambient air as PM10 
(particles with an aerodynamic diameter less than or equal to a nominal 
10 micrometers) by either:
    (i) A reference method based on appendix M of this part and 
designated in accordance with part 53 of this chapter; or
    (ii) 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 98th 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.
    (d) The annual primary and secondary PM10 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 50 
micrograms per cubic meter.
    (e) The 24-hour primary and secondary PM10 standards are 
met when the 99th percentile 24-hour concentration, as 
determined in accordance with appendix N of this part, is less than or 
equal to 150 micrograms per cubic meter.

[62 FR 38711, July 18, 1997]



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

[[Page 9]]

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 
g/m3). 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 g/
m3) 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 no longer 
apply to an area once EPA determines that the area has air quality 
meeting the 1-hour standard. Area designations are codified in 40 CFR 
part 81.

[62 FR 38894, July 18, 1997]



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 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.

[62 FR 38894, July 18, 1997]



Sec. 50.11  National primary and secondary ambient air quality standards for nitrogen dioxide.

    (a) The level of the national primary ambient air quality standard 
for nitrogen dioxide is 0.053 parts per million (100 micrograms per 
cubic meter), annual arithmetic mean concentration.
    (b) The level of national secondary ambient air quality standard for 
nitrogen dioxide is 0.053 parts per million (100 micrograms per cubic 
meter), annual arithmetic mean concentration.
    (c) The levels of the standards shall be measured by:
    (1) A reference method based on appendix F and designated in 
accordance with part 53 of this chapter, or
    (2) An equivalent method designated in accordance with part 53 of 
this chapter.
    (d) The standards are 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.

[50 FR 25544, June 19, 1985]



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

    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.

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

[43 FR 46258, Oct. 5, 1978]

Appendix A 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,

[[Page 10]]

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 (g/std m3).
    3.0 Range.
    3.1 The lower limit of detection of SO2 in 10 mL of TCM 
is 0.75 g (based on collaborative test results).(7) This 
represents a concentration of 25 g SO2/m3 
(0.01 ppm) in an air sample of 30 standard liters (short-term sampling) 
and a concentration of 13 g SO2/m3 (0.005 
ppm) in an air sample of 288 standard liters (long-term sampling). 
Concentrations less than 25 g SO2/m3 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 g of SO2 in 25 mL 
of final solution. This upper limit of the analysis range represents a 
concentration of 1,130 g SO2/m3 (0.43 
ppm) in an air sample of 30 standard liters and a concentration of 590 
g SO2/m3 (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 g Fe (III), 
22 g V (V), 10 g Cu (II), 10 g Mn (II), and 
10 g Cr (III) in 10 mL absorbing reagent can be tolerated in 
the procedure.(10) No significant interference has been encountered with 
2.3 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 g/m\3\ at concentrations of 100 g/m\3\ 
to 7 g/m\3\ at concentrations of 400 g/
m\3\.
 The day-to-day variability within an individual laboratory 
(repeatability) varies linearly with concentration from 18.1 
g/m\3\ at levels of 100 g/m\3\ to 50.9 
g/m\3\ at levels of 400 g/m\3\.
 The day-to-day variability between two or more laboratories 
(reproducibility) varies linearly with concentration from 
36.9 g/m\3\ at levels of 100 g/m\3\ to 
103.5  g/m\3\ at levels of 400 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 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 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 
41 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 
(0.40.1 mm) such that a No. 79 jeweler's drill bit will pass 
through the opening but a No. 78 drill bit

[[Page 11]]

will not. Clearance from the bottom of the absorber to the tip of the 
stem must be 62 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 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 12]]




[[Page 13]]





[[Page 14]]


    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 
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 15]]

    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 O35H2 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 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 16]]

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, 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 
0.0300.002 absorbance unit/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 17]]

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 25SO2/
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 
tubing, or Teflon 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 10.10 
L/min for 30-minute sampling or 0.5000.05 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 1510  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 0.2000.020 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 18]]



    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 19]]

[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 20]]



------------------------------------------------------------------------
                                        Volume of                Total
                                         sulfite-  Volume of  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 g
  SO2/mL; the actual total 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 plus-minus1  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, 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 
plus-minus0.002 absorbance unit/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 (plus-minus0.1  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 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 g 
SO2/m3 (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 g/m3) 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 21]]


Ca = concentration of SO2 at standard conditions, 
g/m3;
Pr = permeation rate, 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 22]]


    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, 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 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 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, g/mL;
Ca = concentration of the standard atmosphere calculated 
according to equation 12, 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 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 23]]

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 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 plus-minus 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 Reaqent 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/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 24]]



                                                    Data Form
                                             [For hand calculations]
----------------------------------------------------------------------------------------------------------------
                                                      Absor- bance
     Calibration point no.       Micro- grams So2        units
----------------------------------------------------------------------------------------------------------------
                                       (x)                (y)                 x2                xy           y2
1.............................  .................  .................  .................  ................  .....
2.............................  .................  .................  .................  ................  .....
3.............................  .................  .................  .................  ................  .....
4.............................  .................  .................  .................  ................  .....
5.............................  .................  .................  .................  ................  .....
6.............................  .................  .................  .................  ................  .....
----------------------------------------------------------------------------------------------------------------

 x=______   y=______   x\2\=______  
xy______  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 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 g. If the difference is 
greater than 1 g, the source of the discrepancy must be 
identified and corrected.
    12.5 Conversion of g/m3 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 25]]

    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]

    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 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 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 (g/std 
m3). 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 
g/std m3. The upper limit is determined by the point 
at which the sampler can no longer maintain the specified

[[Page 26]]

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 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 27]]

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 ().
    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 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. () 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.
---------------------------------------------------------------------------

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

    7.2.2 Minimum sample flow rate, heavily loaded filter: 1.1 
m3/min (39 ft3/min).
---------------------------------------------------------------------------

     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 m3/min 
(60 ft3/min).
    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. 
 This sample air inlet should be approximately 
uniform on all sides of the sampler.  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.  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 28]]

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  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 m3/min over the range 1.0 to 
1.8 std m3/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 m3/min.
    7.8.2 Resolution: 0.02 m3/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 m3/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 m3/min 
(35-64 ft3/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 plus-minus3  deg.C variation during equilibration 
period.
    7.9.2 Controlled humidity: Less than 50 percent relative humidity, 
constant within plus-minus5 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) and the ambient temperature (T 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 m3/min [39-60 ft3/min]), use a different 
filter, or adjust the sampler flow rate. Warning: Substantial flow 
adjustments may affect the

[[Page 29]]

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) and the ambient temperature (T 
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 
different but constant flow rates, evenly distributed, with at least 
three in the specified

[[Page 30]]

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 
m3 of air have passed through the standard volume meter. 
Record the standard volume meter inlet pressure manometer reading as 
P (column 5 in Figure 4), and the orifice manometer reading as 
H (column 7 in Figure 4). Be sure to indicate the correct units 
of measurement.
    9.2.12 After at least 3 m3 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 m3) as 
follows:
[GRAPHIC] [TIFF OMITTED] TR31AU93.024

where:

Vstd = standard volume, std m3;
Vm = actual volume measured by the standard volume meter;
P1 = barometric pressure during calibration, mm Hg or kPa;
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 m3/min) as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.013

where:

Qstd = standard volumetric flow rate, std m3/min
t = elapsed time, minutes.

    Record Qstd to the nearest 0.01 std m3/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 m3/min (35-64 ft\3\/min).
    9.2.16 For each flow, compute

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:

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 (H) and the sampler flow rate indication (I) in the 
appropriate columns of Figure 5.
    9.3.7 Calculate 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: Qstd=1/m 
H(P2/Pstd)(298/T2)-b. 
Record the value of Qstd on Figure 5.

[[Page 31]]

    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 
m3/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 
m3/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 32]]





    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.
    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, 
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 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, 
g/m\3\;

[[Page 33]]

TSP = concentration at standard conditions, 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 34]]





[[Page 35]]





[[Page 36]]





[[Page 37]]




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

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

                          Measurement Principle

    1. Measurements are based on the absorption of infrared radiation by 
carbon monoxide (CO) in a non-dispersive photometer. Infrared energy 
from a source is passed through a cell containing the gas 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 to 
CO by employing CO gas in either the detector or in a filter cell in the 
optical path, thereby limiting the measured absorption to one or more of 
the characteristic wavelengths at which CO strongly absorbs. Optical 
filters or other means may

[[Page 38]]

also be used to limit sensitivity of the photometer to a narrow band of 
interest. Various schemes may be used to provide a suitable zero 
reference for the photometer. The measured absorption is converted to an 
electrical output signal, which is related to the concentration of CO in 
the measurement cell.
    2. 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.
    3. Sampling considerations.
    The use of a particle filter on the sample inlet line of an NDIR CO 
analyzer is optional and left to the discretion of the user or the 
manufacturer. Use of filter should depend on the analyzer's 
susceptibility to interference, malfunction, or damage due to particles.

                          Calibration Procedure

    1. Principle. Either of two methods may be used for dynamic 
multipoint calibration of CO analyzers:
    (1) One method uses a single certified standard cylinder of CO, 
diluted as necessary with zero air, to obtain the various calibration 
concentrations needed.
    (2) The other method uses individual certified standard cylinders of 
CO for each concentration needed. Additional information on calibration 
may be found in Section 2.0.9 of Reference 1.
    2. Apparatus. The major components and typical configurations of the 
calibration systems for the two calibration methods are shown in Figures 
1 and 2.
    2.1 Flow controller(s). Device capable of adjusting and regulating 
flow rates. Flow rates for the dilution method (Figure 1) must be 
regulated to  1%.
    2.2 Flow meter(s). Calibrated flow meter capable of measuring and 
monitoring flow rates. Flow rates for the dilution method (Figure 1) 
must be measured with an accuracy of  2% of the measured 
value.
    2.3 Pressure regulator(s) for standard CO cylinder(s). Regulator 
must have nonreactive diaphragm and internal parts and a suitable 
delivery pressure.
    2.4 Mixing chamber. A chamber designed to provide thorough mixing of 
CO and diluent air for the dilution method.
    2.5 Output manifold. The output manifold 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.
    3. Reagents.
    3.1 CO concentration standard(s). Cylinder(s) of CO in air 
containing appropriate concentrations(s) of CO suitable for the selected 
operating range of the analyzer under calibration; CO standards for the 
dilution method may be contained in a nitrogen matrix if the zero air 
dilution ratio is not less than 100:1. The assay of the cylinder(s) must 
be traceable either to a National Bureau of Standards (NBS) CO in air 
Standard Reference Material (SRM) or to an NBS/EPA-approved commercially 
available Certified Reference Material (CRM). CRM's are described in 
Reference 2, and a list of CRM sources is available from the address 
shown for Reference 2. A recommended protocol for certifying CO gas 
cylinders against either a CO SRM or a CRM is given in Reference 1. CO 
gas cylinders should be recertified on a regular basis as determined by 
the local quality control program.
    3.2 Dilution gas (zero air). Air, free of contaminants which will 
cause a detectable response on the CO analyzer. The zero air should 
contain <0.1 ppm CO. A procedure for generating zero air is given in 
Reference 1.
    4. Procedure Using Dynamic Dilution Method.
    4.1 Assemble a dynamic calibration system such as the one shown in 
Figure 1. All calibration gases including zero air must be introduced 
into the sample inlet of the analyzer system. For specific operating 
instructions refer to the manufacturer's manual.
    4.2 Insure that all flowmeters are properly calibrated, under the 
conditions of use, if appropriate, against an authoritative 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 (101 kPa). A discussion 
on calibration of flowmeters is given in Reference 1.
    4.3 Select the operating range of the CO analyzer to be calibrated.
    4.4 Connect the signal output of the CO analyzer to the input of the 
strip chart recorder or other data collection device. All adjustments to 
the analyzer should be based on the appropriate strip chart or data 
device readings. References to analyzer responses in the procedure given 
below refer to recorder or data device responses.
    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 insure that no ambient 
air is pulled into the manifold vent. Allow the analyzer to sample zero 
air until a stable respose is obtained. After the response has 
stabilized, adjust the analyzer zero control. Offsetting the analyzer 
zero adjustments to +5 percent of scale is recommended to facilitate 
observing negative zero drift. Record the stable zero air response as 
ZCO.
    4.6 Adjust the zero air flow and the CO flow from the standard CO 
cylinder to provide a diluted CO concentration of approximately 80 
percent of the upper range limit (URL) of the operating range of the 
analyzer. 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

[[Page 39]]

pulled into the manifold vent. The exact CO concentration is calculated 
from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.026

where:

[CO]OUT = diluted CO concentration at the output manifold, 
ppm;
[CO]STD = concentration of the undiluted CO standard, ppm;
FCO = flow rate of the CO standard corrected to 25  deg.C and 
760 mm Hg, (101 kPa), L/min; and
FD = flow rate of the dilution air corrected to 25  deg.C and 
760 mm Hg, (101 kPa), L/min.

    Sample this CO concentration until a stable response is obtained. 
Adjust the analyzer span control to obtain a recorder response as 
indicated below:

Recorder response (percent scale) =

[GRAPHIC] [TIFF OMITTED] TR31AU93.027

where:

URL = nominal upper range limit of the analyzer's operating range, and
ZCO = analyzer response to zero air, % scale.

    If substantial adjustment of the analyzer span control is required, 
it may be necessary to recheck the zero and span adjustments by 
repeating Steps 4.5 and 4.6. Record the CO concentration and the 
analyzer's response. 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 (1). Record the concentration and the 
analyzer's response for each concentration. Plot the analyzer responses 
versus the corresponding CO concentrations and draw or calculate the 
calibration curve.
    5. Procedure Using Multiple Cylinder Method. Use the procedure for 
the dynamic dilution method with the following changes:
    5.1 Use a multi-cylinder system such as the typical one shown in 
Figure 2.
    5.2 The flowmeter need not be accurately calibrated, provided the 
flow in the output manifold exceeds the analyzer's flow demand.
    5.3 The various CO calibration concentrations required in Steps 4.6 
and 4.7 are obtained without dilution by selecting the appropriate 
certified standard cylinder.

                               References

    1. Quality Assurance Handbook for Air Pollution Measurement Systems, 
Volume II--Ambient Air Specific Methods, EPA-600/4-77-027a, U.S. 
Environmental Protection Agency, Environmental Monitoring Systems 
Laboratory, Research Triangle Park, NC 27711, 1977.
    2. 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.

[[Page 40]]




[[Page 41]]




[47 FR 54922, Dec. 6, 1982; 48 FR 17355, Apr. 22, 1983]

[[Page 42]]

 Appendix D to Part 50--Measurement Principle and Calibration Procedure 
             for the Measurement of Ozone in the Atmosphere

                          measurement principle

    1. Ambient air and ethylene are delivered simultaneously to a mixing 
zone where the ozone in the air reacts with the ethylene to emit light, 
which is detected by a photomultiplier tube. The resulting photocurrent 
is amplified and is either read directly or displayed on a recorder.
    2. 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 and calibrated as follows:

                          calibration procedure

    1. Principle. The calibration procedure is based on the photometric 
assay of ozone (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 
() of O3 at 254 nm, (2) the optical path length (l) 
through the sample, (3) the transmittance of the sample at a 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] TR31AU93.028

where:

 = absorption coefficient of O3 at 254 
nm=308plus-minus4 atm-1 cm-1 at 0 
deg.C and 760 torr. (1, 2, 3, 4, 5, 
6, 7)
c = O3 concentration in atmospheres
l = optical path length in cm

    In practice, a stable O3 generator is used to produce 
O3 concentrations over the required 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] TR31AU93.029

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.
    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 8.
    3. Apparatus. A complete UV calibration system consists of an ozone 
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 ozone concentration at the system output and allow 
the photometer to accurately assay the output concentration to the 
precision specified for the photometer (3.1). Figure 1 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 should be 
of glass, Teflon, or other relatively inert materials. Additional 
information regarding the assembly of a UV photometric calibration 
apparatus is given in Reference 9. 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 1; see Reference 8 for guidance.
    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 1. 
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

[[Page 43]]

minimize loss of O3 from contact with cell walls and gas 
handling components. See Reference 9 for additional information.
    3.2 Air flow controllers. Devices capable of regulating air flows as 
necessary to meet the output stability and photometer precision 
requirements.
    3.3 Ozone generator. Device capable of generating stable levels of 
O3 over the required concentration range.
    3.4 Output manifold. The output manifold should 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.
    3.5 Two-way valve. Manual or automatic valve, or other means to 
switch the photometer flow between zero air and the O3 
concentration.
    3.6 Temperature indicator. Accurate to plus-minus1 
deg.C.
    3.7 Barometer or pressure indicator. Accurate to 
plus-minus2 torr.
    4. Reagents.
    4.1 Zero air. The zero air must be free of contaminants which would 
cause a detectable response from the O3 analyzer, and it 
should be free of NO, C2 H4, and other species 
which react with O3. A procedure for generating suitable zero 
air is given in Reference 9. As shown in Figure 1, 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 ozone concentration to be assayed (I measurement). When using the 
photometer to certify a transfer standard having its own source of 
ozone, see Reference 8 for guidance on meeting this requirement.
    5. Procedure.
    5.1 General operation. The calibration photometer must be dedicated 
exclusively to use as a calibration standard. It should always be used 
with clean, filtered calibration gases, and never used for ambient air 
sampling. Consideration should be given to locating the calibration 
photometer in a clean laboratory where it can be stationary, protected 
from physical shock, operated by a responsible analyst, and used as a 
common standard for all field calibrations via transfer standards.
    5.2 Preparation. Proper operation of the photometer is of critical 
importance to the accuracy of this procedure. The following steps will 
help to verify proper operation. The steps are not necessarily required 
prior to each use of the photometer. Upon initial operation of the 
photometer, these steps should be carried out frequently, 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 consistent with the documented 
stability of the photometer.
    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.
    5.2.2 System check: Check the photometer system for integrity, 
leaks, cleanliness, proper flowrates, etc. Service or replace filters 
and zero air scrubbers or other consumable materials, as necessary.
    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 (0.5 or 1.0 ppm), then accurately dilute that concentration with 
zero air and reassay 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] TR31AU93.030

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 9.
    5.2.4 Intercomparison: When possible, the photometer should be 
occasionally intercompared, either directly or via transfer standards, 
with calibration photometers used by other agencies or laboratories.
    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 9.
    5.3 Assay of O3 concentrations.
    5.3.1 Allow the photometer system to warm up and stabilizer.
    5.3.2 Verify that the flowrate 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.

[[Page 44]]

    5.3.3 Insure that the flowrate into the output manifold is at least 
1 liter/min greater than the total flowrate required by the photometer 
and any other flow demand connected to the manifold.
    5.3.4 Insure that the flowrate of zero air, Fz, is at 
least 1 liter/min greater than the flowrate required by the photometer.
    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=Io).
    Note: In some commercially available photometers, the operation of 
the two-way valve and various other operations in section 5.3 may be 
carried out automatically by the photometer.
    5.3.6 Adjust the O3 generator to produce an O3 
concentration as needed.
    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.
    5.3.8 Actuate the two-way valve to allow the photometer to sample 
the ozone concentration until the absorption cell is thoroughly flushed 
and record the stable measured value of I.
    5.3.9 Record the temperature and pressure of the sample in the 
photometer absorption cell. (See Reference 9 for guidance.)
    5.3.10 Calculate the O3 concentration from equation 4. An 
average of several determinations will provide better precision.
[GRAPHIC] [TIFF OMITTED] TR31AU93.032

where:

[O3]OUT = O3 concentration, ppm
 = 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 5.2.5=(1-fraction 
O3 lost).

    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 9 for guidance.
    5.3.11 Obtain additional O3 concentration standards as 
necessary by repeating steps 5.3.6 to 5.3.10 or by Option 1.
    5.4 Certification of transfer standards. A transfer standard is 
certified by relating the output of the transfer standard to one or more 
ozone standards as determined according to section 5.3. The exact 
procedure varies depending on the nature and design of the transfer 
standard. Consult Reference 8 for guidance.
    5.5 Calibration of ozone analyzers. Ozone analyzers are calibrated 
as follows, using ozone standards obtained directly according to section 
5.3 or by means of a certified transfer standard.
    5.5.1 Allow sufficient time for the O3 analyzer and the 
photometer or transfer standard to warmup and stabilize.
    5.5.2 Allow the O3 analyzer to sample zero air until a 
stable response is obtained and 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. Record the 
stable zero air response as ``Z''.
    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.
    5.5.4 Adjust the O3 analyzer's span control to obtain a 
convenient recorder response as indicated below:
    recorder response (%scale) =
    [GRAPHIC] [TIFF OMITTED] TR31AU93.033
    
where:

URL = upper range limit of the O3 analyzer, ppm
Z = recorder response with zero air, % scale

    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 
5.5.2 to 5.5.4.
    5.5.5 Generate several other O3 concentration standards 
(at least 5 others are recommended) over the scale range of the O3 
analyzer by adjusting the O3 source or by Option 1. For each 
O3 concentration standard, record the O3 and the 
corresponding analyzer response.
    5.5.6 Plot the O3 analyzer responses versus the 
corresponding O3 concentrations and draw the O3 
analyzer's calibration curve or calculate the appropriate response 
factor.
    5.5.7 Option 1: The various O3 concentrations required in 
steps 5.3.11 and 5.5.5 may be obtained by dilution of the O3 
concentration generated in steps 5.3.6 and 5.5.3. With this option, 
accurate flow measurements are required. The dynamic calibration system 
may be modified as shown in Figure 2 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 flowrate through the O3 generator 
(Fo) and the dilution air flowrate

[[Page 45]]

(FD) are measured with a reliable flow or volume standard 
traceable to NBS. Each O3 concentration generated by dilution 
is calculated from:
[GRAPHIC] [TIFF OMITTED] TR31AU93.031

where:

[O3]'OUT = diluted O3 concentration, 
ppm
F0 = flowrate through the O3 generator, liter/min
FD = diluent air flowrate, liter/min

                               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).
    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. Transfer Standards for Calibration of Ambient Air Monitoring 
Analyzers for Ozone, EPA publication number EPA-600/4-79-056, EPA, 
National Exposure Research Laboratory, Department E, (MD-77B), Research 
Triangle Park, NC 27711.
    9. Technical Assistance Document for the Calibration of Ambient 
Ozone Monitors, EPA publication number EPA-600/4-79-057, EPA, National 
Exposure Research Laboratory, Department E, (MD-77B), Research Triangle 
Park, NC 27711.

[[Page 46]]




[[Page 47]]



[44 FR 8224, Feb. 8, 1979, as amended at 62 FR 38895, July 18, 1997]

                    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)

                       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/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, or 
other non-reactive material.
    1.2.1 Air flow controllers. Devices capable of maintaining constant 
air flows within plus-minus2% of the required flowrate.
    1.2.2 NO flow controller. A device capable of maintaining constant 
NO flows within plus-minus2% 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 plus-minus2% of 
the measured flowrate.
    1.2.4 NO flowmeter. A calibrated flowmeter capable of measuring and 
monitoring NO flowrates with an accuracy of plus-minus2% 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.

[[Page 48]]

    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, or other nonreactive material.
    1.2.8 Reaction chamber. A chamber, constructed of glass, 
Teflon, 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, 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, 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 
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 scm3.
    (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


[[Page 49]]


    (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 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

[[Page 50]]

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 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.

[[Page 51]]

    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.
    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 (plus-minus0.1  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, or other non-reactive material.
    2.2.1 Air flow controllers. Devices capable of maintaining constant 
air flows within plus-minus2% of the required flowrate.
    2.2.2 NO flow controller. A device capable of maintaining constant 
NO flows within plus-minus2% 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 plus-minus2% of 
the measured flowrate.
    2.2.4 NO flowmeter. A calibrated flowmeter capable of measuring and 
monitoring NO flowrates with an accuracy of plus-minus2% 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 plus-minus0.1  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 plus-minus0.05  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, or 
other nonreactive material.
    2.2.10 Mixing chamber. A chamber constructed of glass, 
Teflon, 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, 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

[[Page 52]]

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 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 plus-minus0.1  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

[[Page 53]]

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, scm3/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:

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:


[[Page 54]]


[NO2]OUT = diluted NO2 concentration at 
the output manifold, ppm
R = permeation rate, g/min
K = 0.532l NO2/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, 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,

[[Page 55]]

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 56]]




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

Appendix G to Part 50--Reference Method for the Determination of Lead in 
         Suspended Particulate Matter Collected From Ambient Air

    1. Principle and applicability.
    1.1 Ambient air suspended particulate matter is collected on a 
glass-fiber filter for 24 hours using a high volume air sampler. The 
analysis of the 24-hour samples may be performed for either individual 
samples or composites of the samples collected over a calendar month or 
quarter, provided that the compositing procedure has been approved in 
accordance with section 2.8 of appendix C to part 58 of this chapter--
Modifications of methods by users. (Guidance or assistance in requesting 
approval under Section 2.8 can be obtained from the address given in 
section 2.7 of appendix C to part 58 of this chapter.)
    1.2 Lead in the particulate matter is solubilized by extraction with 
nitric acid (HNO3), facilitated by heat or by a mixture of 
HNO3 and hydrochloric acid (HCl) facilitated by 
ultrasonication.
    1.3 The lead content of the sample is analyzed by atomic absorption 
spectrometry using an air-acetylene flame, the 283.3 or 217.0 nm lead 
absorption line, and the optimum instrumental conditions recommended by 
the manufacturer.
    1.4 The ultrasonication extraction with HNO3/HCl will 
extract metals other than lead from ambient particulate matter.
    2. Range, sensitivity, and lower detectable limit. The values given 
below are typical of the methods capabilities. Absolute values will vary 
for individual situations depending on the type of instrument used, the 
lead line, and operating conditions.
    2.1 Range. The typical range of the method is 0.07 to 7.5 g 
Pb/m3 assuming an upper linear range of analysis of 15 
g/ml and an air volume of 2,400 m3.
    2.2 Sensitivity. Typical sensitivities for a 1 percent change in 
absorption (0.0044 absorbance units) are 0.2 and 0.5 g Pb/ml 
for the 217.0 and 283.3 nm lines, respectively.
    2.3 Lower detectable limit (LDL). A typical LDL is 0.07 g 
Pb/m3. The above value was calculated by doubling the 
between-laboratory standard deviation obtained for the lowest measurable 
lead concentration in a collaborative test of the method.(15) An air 
volume of 2,400 m3 was assumed.
    3. Interferences. Two types of interferences are possible: chemical 
and light scattering.
    3.1 Chemical. Reports on the absence (1, 2, 3, 4, 5) of chemical 
interferences far outweigh those reporting their presence, (6) 
therefore, no correction for chemical interferences is given here. If 
the analyst suspects that the sample matrix is causing a chemical 
interference, the interference can be verified and corrected for by 
carrying out the analysis with and without the method of standard 
additions.(7)

[[Page 57]]

    3.2 Light scattering. Nonatomic absorption or light scattering, 
produced by high concentrations of dissolved solids in the sample, can 
produce a significant interference, especially at low lead 
concentrations. (2) The interference is greater at the 217.0 nm line 
than at the 283.3 nm line. No interference was observed using the 283.3 
nm line with a similar method.(1)
    Light scattering interferences can, however, be corrected for 
instrumentally. Since the dissolved solids can vary depending on the 
origin of the sample, the correction may be necessary, especially when 
using the 217.0 nm line. Dual beam instruments with a continuum source 
give the most accurate correction. A less accurate correction can be 
obtained by using a nonabsorbing lead line that is near the lead 
analytical line. Information on use of these correction techniques can 
be obtained from instrument manufacturers' manuals.
    If instrumental correction is not feasible, the interference can be 
eliminated by use of the ammonium pyrrolidinecarbodithioate-
methylisobutyl ketone, chelation-solvent extraction technique of sample 
preparation.(8)
    4. Precision and bias.
    4.1 The high-volume sampling procedure used to collect ambient air 
particulate matter has a between-laboratory relative standard deviation 
of 3.7 percent over the range 80 to 125 g/m3.(9) The 
combined extraction-analysis procedure has an average within-laboratory 
relative standard deviation of 5 to 6 percent over the range 1.5 to 15 
g Pb/ml, and an average between laboratory relative standard 
deviation of 7 to 9 percent over the same range. These values include 
use of either extraction procedure.
    4.2 Single laboratory experiments and collaborative testing indicate 
that there is no significant difference in lead recovery between the hot 
and ultrasonic extraction procedures.(15)
    5. Apparatus.
    5.1 Sampling.
    5.1.1 High-Volume Sampler. Use and calibrate the sampler as 
described in appendix B to this part.
    5.2 Analysis.
    5.2.1 Atomic absorption spectrophotometer. Equipped with lead hollow 
cathode or electrodeless discharge lamp.
    5.2.1.1 Acetylene. The grade recommended by the instrument 
manufacturer should be used. Change cylinder when pressure drops below 
50-100 psig.
    5.2.1.2 Air. Filtered to remove particulate, oil, and water.
    5.2.2 Glassware. Class A borosilicate glassware should be used 
throughout the analysis.
    5.2.2.1 Beakers. 30 and 150 ml. graduated, Pyrex.
    5.2.2.2 Volumetric flasks. 100-ml.
    5.2.2.3 Pipettes. To deliver 50, 30, 15, 8, 4, 2, 1 ml.
    5.2.2.4 Cleaning. All glassware should be scrupulously cleaned. The 
following procedure is suggested. Wash with laboratory detergent, rinse, 
soak for 4 hours in 20 percent (w/w) HNO3, rinse 3 times with 
distilled-deionized water, and dry in a dust free manner.
    5.2.3 Hot plate.
    5.2.4. Ultrasonication water bath, unheated. Commercially available 
laboratory ultrasonic cleaning baths of 450 watts or higher ``cleaning 
power,'' i.e., actual ultrasonic power output to the bath have been 
found satisfactory.
    5.2.5 Template. To aid in sectioning the glass-fiber filter. See 
figure 1 for dimensions.
    5.2.6 Pizza cutter. Thin wheel. Thickness 1mm.
    5.2.7 Watch glass.
    5.2.8 Polyethylene bottles. For storage of samples. Linear 
polyethylene gives better storage stability than other polyethylenes and 
is preferred.
    5.2.9 Parafilm ``M''.\1\ American Can Co., Marathon Products, 
Neenah, Wis., or equivalent.
---------------------------------------------------------------------------

    \1\ Mention of commercial products does not imply endorsement by the 
U.S. Environmental Protection Agency.
---------------------------------------------------------------------------

    6. Reagents.
    6.1 Sampling.
    6.1.1 Glass fiber filters. The specifications given below are 
intended to aid the user in obtaining high quality filters with 
reproducible properties. These specifications have been met by EPA 
contractors.
    6.1.1.1 Lead content. The absolute lead content of filters is not 
critical, but low values are, of course, desirable. EPA typically 
obtains filters with a lead content of 75 g/filter.
    It is important that the variation in lead content from filter to 
filter, within a given batch, be small.
    6.1.1.2 Testing.
    6.1.1.2.1 For large batches of filters (>500 filters) select at 
random 20 to 30 filters from a given batch. For small batches (>500 
filters) a lesser number of filters may be taken. Cut one \3/4\" x 8" 
strip from each filter anywhere in the filter. Analyze all strips, 
separately, according to the directions in sections 7 and 8.
    6.1.1.2.2 Calculate the total lead in each filter as
    [GRAPHIC] [TIFF OMITTED] TC08NO91.084
    
where:

Fb = Amount of lead per 72 square inches of filter, 
g.

    6.1.1.2.3 Calculate the mean, Fb, of the values and the 
relative standard deviation (standard deviation/mean  x  100). If the 
relative standard deviation is high enough so

[[Page 58]]

that, in the analysts opinion, subtraction of Fb, (section 
10.3) may result in a significant error in the g Pb/m3, 
the batch should be rejected.
    6.1.1.2.4 For acceptable batches, use the value of Fb to 
correct all lead analyses (section 10.3) of particulate matter collected 
using that batch of filters. If the analyses are below the LDL (section 
2.3) no correction is necessary.
    6.2 Analysis.
    6.2.1 Concentrated (15.6 M) HNO3. ACS reagent grade 
HNO3 and commercially available redistilled HNO3 
has found to have sufficiently low lead concentrations.
    6.2.2 Concentrated (11.7 M) HCl. ACS reagent grade.
    6.2.3 Distilled-deionized water. (D.I. water).
    6.2.4 3 M HNO3. This solution is used in the hot 
extraction procedure. To prepare, add 192 ml of concentrated HNO3 
to D.I. water in a 1 l volumetric flask. Shake well, cool, and dilute to 
volume with D.I. water. Caution: Nitric acid fumes are toxic. Prepare in 
a well ventilated fume hood.
    6.2.5 0.45 M HNO3. This solution is used as the matrix 
for calibration standards when using the hot extraction procedure. To 
prepare, add 29 ml of concentrated HNO3 to D.I. water in a 1 
l volumetric flask. Shake well, cool, and dilute to volume with D.I. 
water.
    6.2.6 2.6 M HNO3+0 to 0.9 M HCl. This solution is used in 
the ultrasonic extraction procedure. The concentration of HCl can be 
varied from 0 to 0.9 M. Directions are given for preparation of a 2.6 M 
HNO3+0.9 M HCl solution. Place 167 ml of concentrated 
HNO3 into a 1 l volumetric flask and add 77 ml of 
concentrated HCl. Stir 4 to 6 hours, dilute to nearly 1 l with D.I. 
water, cool to room temperature, and dilute to 1 l.
    6.2.7 0.40 M HNO3 + X M HCl. This solution is used as the 
matrix for calibration standards when using the ultrasonic extraction 
procedure. To prepare, add 26 ml of concentrated HNO3, plus 
the ml of HCl required, to a 1 l volumetric flask. Dilute to nearly 1 l 
with D.I. water, cool to room temperature, and dilute to 1 l. The amount 
of HCl required can be determined from the following equation:
[GRAPHIC] [TIFF OMITTED] TC08NO91.085

where:

y = ml of concentrated HCl required.
x = molarity of HCl in 6.2.6.
0.15 = dilution factor in 7.2.2.

    6.2.8 Lead nitrate, Pb(NO3)2. ACS reagent 
grade, purity 99.0 percent. Heat for 4 hours at 120  deg.C and cool in a 
desiccator.
    6.3 Calibration standards.
    6.3.1 Master standard, 1000 g Pb/ml in HNO3. 
Dissolve 1.598 g of Pb(NO3)2 in 0.45 M HNO3 
contained in a 1 l volumetric flask and dilute to volume with 0.45 M 
HNO3.
    6.3.2 Master standard, 1000 g Pb/ml in HNO3/HCl. 
Prepare as in section 6.3.1 except use the HNO3/HCl solution 
in section 6.2.7.
    Store standards in a polyethylene bottle. Commercially available 
certified lead standard solutions may also be used.
    7. Procedure.
    7.1 Sampling. Collect samples for 24 hours using the procedure 
described in reference 10 with glass-fiber filters meeting the 
specifications in section 6.1.1. Transport collected samples to the 
laboratory taking care to minimize contamination and loss of sample. 
(16).
    7.2 Sample preparation.
    7.2.1 Hot extraction procedure.
    7.2.1.1 Cut a \3/4\" x 8" strip from the exposed filter using a 
template and a pizza cutter as described in Figures 1 and 2. Other 
cutting procedures may be used.
    Lead in ambient particulate matter collected on glass fiber filters 
has been shown to be uniformly distributed across the filter.1, 
3, 11 Another study 12 has shown that when 
sampling near a roadway, strip position contributes significantly to the 
overall variability associated with lead analyses. Therefore, when 
sampling near a roadway, additional strips should be analyzed to 
minimize this variability.
    7.2.1.2 Fold the strip in half twice and place in a 150-ml beaker. 
Add 15 ml of 3 M HNO3 to cover the sample. The acid should 
completely cover the sample. Cover the beaker with a watch glass.
    7.2.1.3 Place beaker on the hot-plate, contained in a fume hood, and 
boil gently for 30 min. Do not let the sample evaporate to dryness. 
Caution: Nitric acid fumes are toxic.
    7.2.1.4 Remove beaker from hot plate and cool to near room 
temperature.
    7.2.1.5 Quantitatively transfer the sample as follows:
    7.2.1.5.1 Rinse watch glass and sides of beaker with D.I. water.
    7.2.1.5.2 Decant extract and rinsings into a 100-ml volumetric 
flask.
    7.2.1.5.3 Add D.I. water to 40 ml mark on beaker, cover with watch 
glass, and set aside for a minimum of 30 minutes. This is a critical 
step and cannot be omitted since it allows the HNO3 trapped 
in the filter to diffuse into the rinse water.
    7.2.1.5.4 Decant the water from the filter into the volumetric 
flask.
    7.2.1.5.5 Rinse filter and beaker twice with D.I. water and add 
rinsings to volumetric flask until total volume is 80 to 85 ml.
    7.2.1.5.6 Stopper flask and shake vigorously. Set aside for 
approximately 5 minutes or until foam has dissipated.
    7.2.1.5.7 Bring solution to volume with D.I. water. Mix thoroughly.
    7.2.1.5.8 Allow solution to settle for one hour before proceeding 
with analysis.

[[Page 59]]

    7.2.1.5.9 If sample is to be stored for subsequent analysis, 
transfer to a linear polyethylene bottle.
    7.2.2 Ultrasonic extraction procedure.
    7.2.2.1 Cut a \3/4\" x 8" strip from the exposed filter as described 
in section 7.2.1.1.
    7.2.2.2 Fold the strip in half twice and place in a 30 ml beaker. 
Add 15 ml of the HNO3/HCl solution in section 6.2.6. The acid 
should completely cover the sample. Cover the beaker with parafilm.
    The parafilm should be placed over the beaker such that none of the 
parafilm is in contact with water in the ultrasonic bath. Otherwise, 
rinsing of the parafilm (section 7.2.2.4.1) may contaminate the sample.
    7.2.2.3 Place the beaker in the ultrasonication bath and operate for 
30 minutes.
    7.2.2.4 Quantitatively transfer the sample as follows:
    7.2.2.4.1 Rinse parafilm and sides of beaker with D.I. water.
    7.2.2.4.2 Decant extract and rinsings into a 100 ml volumetric 
flask.
    7.2.2.4.3 Add 20 ml D.I. water to cover the filter strip, cover with 
parafilm, and set aside for a minimum of 30 minutes. This is a critical 
step and cannot be omitted. The sample is then processed as in sections 
7.2.1.5.4 through 7.2.1.5.9.
    Note: Samples prepared by the hot extraction procedure are now in 
0.45 M HNO3. Samples prepared by the ultrasonication 
procedure are in 0.40 M HNO3 + X M HCl.
    8. Analysis.
    8.1 Set the wavelength of the monochromator at 283.3 or 217.0 nm. 
Set or align other instrumental operating conditions as recommended by 
the manufacturer.
    8.2 The sample can be analyzed directly from the volumetric flask, 
or an appropriate amount of sample decanted into a sample analysis tube. 
In either case, care should be taken not to disturb the settled solids.
    8.3 Aspirate samples, calibration standards and blanks (section 9.2) 
into the flame and record the equilibrium absorbance.
    8.4 Determine the lead concentration in g Pb/ml, from the 
calibration curve, section 9.3.
    8.5 Samples that exceed the linear calibration range should be 
diluted with acid of the same concentration as the calibration standards 
and reanalyzed.
    9. Calibration.
    9.1 Working standard, 20 g Pb/ml. Prepared by diluting 2.0 
ml of the master standard (section 6.3.1 if the hot acid extraction was 
used or section 6.3.2 if the ultrasonic extraction procedure was used) 
to 100 ml with acid of the same concentration as used in preparing the 
master standard.
    9.2 Calibration standards. Prepare daily by diluting the working 
standard, with the same acid matrix, as indicated below. Other lead 
concentrations may be used.

------------------------------------------------------------------------
                                                           Concentration
 Volume of 20 g/ml working standard,     Final    g Pb/
                      ml                       volume, ml        ml
------------------------------------------------------------------------
0............................................         100             0
1.0..........................................         200           0.1
2.0..........................................         200           0.2
2.0..........................................         100           0.4
4.0..........................................         100           0.8
8.0..........................................         100           1.6
15.0.........................................         100           3.0
30.0.........................................         100           6.0
50.0.........................................         100          10.0
100.0........................................         100          20.0
------------------------------------------------------------------------

    9.3 Preparation of calibration curve. Since the working range of 
analysis will vary depending on which lead line is used and the type of 
instrument, no one set of instructions for preparation of a calibration 
curve can be given. Select standards (plus the reagent blank), in the 
same acid concentration as the samples, to cover the linear absorption 
range indicated by the instrument manufacturer. Measure the absorbance 
of the blank and standards as in section 8.0. Repeat until good 
agreement is obtained between replicates. Plot absorbance (y-axis) 
versus concentration in g Pb/ml (x-axis). Draw (or compute) a 
straight line through the linear portion of the curve. Do not force the 
calibration curve through zero. Other calibration procedures may be 
used.
    To determine stability of the calibration curve, remeasure--
alternately--one of the following calibration standards for every 10th 
sample analyzed: Concentration ls-thn-eq 1g Pb/ml; 
concentration ls-thn-eq 10 g Pb/ml. If either 
standard deviates by more than 5 percent from the value predicted by the 
calibration curve, recalibrate and repeat the previous 10 analyses.
    10. Calculation.
    10.1 Measured air volume. Calculate the measured air volume at 
Standard Temperature and Pressure as described in Reference 10.
    10.2 Lead concentration. Calculate lead concentration in the air 
sample.



[[Page 60]]


where:

C = Concentration, g Pb/sm3.
g Pb/ml = Lead concentration determined from section 8.
100 ml/strip = Total sample volume.
12 strips = Total useable filter area, 8" x 9". Exposed area of one 
strip, \3/4\" x 7".
Filter = Total area of one strip, \3/4\" x 8".
Fb = Lead concentration of blank filter, g, from 
section 6.1.1.2.3.
VSTP = Air volume from section 10.2.

    11. Quality control.
    \3/4\" x 8" glass fiber filter strips containing 80 to 2000 
g Pb/strip (as lead salts) and blank strips with zero Pb 
content should be used to determine if the method--as being used--has 
any bias. Quality control charts should be established to monitor 
differences between measured and true values. The frequency of such 
checks will depend on the local quality control program.
    To minimize the possibility of generating unreliable data, the user 
should follow practices established for assuring the quality of air 
pollution data, (13) and take part in EPA's semiannual audit program for 
lead analyses.
    12. Trouble shooting.
    1. During extraction of lead by the hot extraction procedure, it is 
important to keep the sample covered so that corrosion products--formed 
on fume hood surfaces which may contain lead--are not deposited in the 
extract.
    2. The sample acid concentration should minimize corrosion of the 
nebulizer. However, different nebulizers may require lower acid 
concentrations. Lower concentrations can be used provided samples and 
standards have the same acid concentration.
    3. Ashing of particulate samples has been found, by EPA and 
contractor laboratories, to be unnecessary in lead analyses by atomic 
absorption. Therefore, this step was omitted from the method.
    4. Filtration of extracted samples, to remove particulate matter, 
was specifically excluded from sample preparation, because some analysts 
have observed losses of lead due to filtration.
    5. If suspended solids should clog the nebulizer during analysis of 
samples, centrifuge the sample to remove the solids.
    13. Authority.
    (Secs. 109 and 301(a), Clean Air Act, as amended (42 U.S.C. 7409, 
7601(a)))
    14. References.
    1. Scott, D. R. et al. ``Atomic Absorption and Optical Emission 
Analysis of NASN Atmospheric Particulate Samples for Lead.'' Envir. Sci. 
and Tech., 10, 877-880 (1976).
    2. Skogerboe, R. K. et al. ``Monitoring for Lead in the 
Environment.'' pp. 57-66, Department of Chemistry, Colorado State 
University, Fort Collins, CO 80523. Submitted to National Science 
Foundation for publications, 1976.
    3. Zdrojewski, A. et al. ``The Accurate Measurement of Lead in 
Airborne Particulates.'' Inter. J. Environ. Anal. Chem., 2, 63-77 
(1972).
    4. Slavin, W., ``Atomic Absorption Spectroscopy.'' Published by 
Interscience Company, New York, NY (1968).
    5. Kirkbright, G. F., and Sargent, M., ``Atomic Absorption and 
Fluorescence Spectroscopy.'' Published by Academic Press, New York, NY 
1974.
    6. Burnham, C. D. et al., ``Determination of Lead in Airborne 
Particulates in Chicago and Cook County, IL, by Atomic Absorption 
Spectroscopy.'' Envir. Sci. and Tech., 3, 472-475 (1969).
    7. ``Proposed Recommended Practices for Atomic Absorption 
Spectrometry.'' ASTM Book of Standards, part 30, pp. 1596-1608 (July 
1973).
    8. Koirttyohann, S. R. and Wen, J. W., ``Critical Study of the APCD-
MIBK Extraction System for Atomic Absorption.'' Anal. Chem., 45, 1986-
1989 (1973).
    9. Collaborative Study of Reference Method for the Determination of 
Suspended Particulates in the Atmosphere (High Volume Method). 
Obtainable from National Technical Information Service, Department of 
Commerce, Port Royal Road, Springfield, VA 22151, as PB-205-891.
    10. [Reserved]
    11. Dubois, L., et al., ``The Metal Content of Urban Air.'' JAPCA, 
16, 77-78 (1966).
    12. EPA Report No. 600/4-77-034, June 1977, ``Los Angeles Catalyst 
Study Symposium.'' Page 223.
    13. Quality Assurance Handbook for Air Pollution Measurement System. 
Volume 1--Principles. EPA-600/9-76-005, March 1976.
    14. Thompson, R. J. et al., ``Analysis of Selected Elements in 
Atmospheric Particulate Matter by Atomic Absorption.'' Atomic Absorption 
Newsletter, 9, No. 3, May-June 1970.
    15. To be published. EPA, QAB, EMSL, RTP, N.C. 27711
    16. Quality Assurance Handbook for Air Pollution Measurement 
Systems. Volume II--Ambient Air Specific Methods. EPA-600/4-77/027a, May 
1977.

[[Page 61]]




[[Page 62]]




(Secs. 109, 301(a) of the Clean Air Act, as amended (42 U.S.C. 7409, 
7601(a)); secs. 110, 301(a) and 319 of the Clean Air Act (42 U.S.C. 
7410, 7601(a), 7619))

[43 FR 46258, Oct. 5, 1978; 44 FR 37915, June 29, 1979, as amended at 46 
FR 44163, Sept. 3, 1981; 52 FR 24664, July 1, 1987]

    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 g/m3) 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.''

[[Page 63]]

    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).
    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]

[[Page 64]]

    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 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

[[Page 65]]

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%
----------------------------------------------------------------------------------------------------------------

    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]

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

    1.0 Applicability.

[[Page 66]]

    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 (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 
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 g/
m\3\ for PM10 concentrations below 80 g/m\3\ and 7 
percent for PM10 concentrations above 80 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 for an ideal sampler whose 
sampling effectiveness is explicitly specified. Also, the particle size 
for 50 percent sampling effectivensss is required to be 
100.5 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

[[Page 67]]

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 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 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

[[Page 68]]

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 m particles at the sampler's 
operating face velocity.
    7.2.3 Integrity. 5 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 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

[[Page 69]]

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 241 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.
    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

[[Page 70]]

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

   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 and 
annual 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 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 an arithmetic mean. All particulate matter 
standards are expressed in terms of expected annual values: Expected 
number of exceedances per year for the 24-hour standards and expected 
annual arithmetic mean for the annual standards.
    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

[[Page 71]]

rounding to the nearest 10 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  Annual Primary and Secondary Standards. Under 40 CFR 50.6(b), 
the annual primary and secondary standards are attained when the 
expected annual arithmetic mean PM10 concentration is less 
than or equal to the level of the standard. In the simplest case, the 
expected annual arithmetic mean is determined by averaging the annual 
arithmetic mean PM10 concentrations for the past 3 calendar 
years. Because of the potential for incomplete data and the possible 
seasonality in PM10 concentrations, the annual mean shall be 
calculated by averaging the four quarterly means of 
PM10 concentrations within the calendar year. The equations 
for calculating the annual arithmetic mean are given in section 4.0 of 
this appendix. 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. The expected annual arithmetic 
mean is rounded to the nearest 1 g/m\3\ before comparison with 
the annual standards (fractional values equal to or greater than 0.5 are 
to be rounded up).
    2.3  Data Requirements.
    (a) 40 CFR 58.13 specifies the required minimum frequency of 
sampling for PM10. For the purposes of making comparisons 
with the particulate matter standards, all data produced by National Air 
Monitoring Stations (NAMS), 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 either the annual or 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 sections 3.0 and 4.0 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). Nonattainment of 
the annual standards can be demonstrated on the basis of quarterly mean 
concentrations developed from observed data combined with one-half the 
minimum detectable concentration substituted for missing values. In both 
cases, expected annual values must exceed the levels allowed by the 
standards.
    2.4  Adjustment for Exceptional Events and Trends.

[[Page 72]]

    (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 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:

                               Equation 1
[GRAPHIC] [TIFF OMITTED] TR18JY97.180

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.

                               Equation 2
[GRAPHIC] [TIFF OMITTED] TR18JY97.181

    (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 58.13; 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 73]]

                                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 58.13. 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 eqution 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:

                               Equation 3
[GRAPHIC] [TIFF OMITTED] TR18JY97.182

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.

    4.0 Computational Equations for Annual Standards.
    4.1 Calculation of the Annual Arithmetic Mean. (a) An annual 
arithmetic mean value for PM10 is determined by averaging the 
quarterly means for the 4 calendar quarters of the year. The following 
equation is to be used for calculation of the mean for a calendar 
quarter:

                               Equation 4
[GRAPHIC] [TIFF OMITTED] TR18JY97.183

where:

xq = the quarterly mean concentration for quarter q, q=1, 2, 
3, or 4,
nq = the number of samples in the quarter, and
xi = the ith concentration value recorded in the quarter.

    (b) The quarterly mean, expressed in g/m\3\, must be 
rounded to the nearest tenth (fractional values of 0.05 should be 
rounded up).

[[Page 74]]

    (c) The annual mean is calculated by using the following equation:

                               Equation 5
[GRAPHIC] [TIFF OMITTED] TR18JY97.184

where:

x = the annual mean; and
xq = the mean for calendar quarter q.

    (d) The average of quarterly means must be rounded to the nearest 
tenth (fractional values of 0.05 should be rounded up).
    (e) The use of quarterly averages to compute the annual average will 
not be necessary for monitoring or modeling data which results in a 
complete record, i.e., 365 days per year.
    (f) The expected annual mean is estimated as the average of three or 
more annual means. This multi-year estimate, expressed in g/
m\3\, shall be rounded to the nearest integer for comparison with the 
annual standard (fractional values of 0.5 should be rounded up).

                                Example 4

    Using Equation 4, the quarterly means are calculated for each 
calendar quarter. If the quarterly means are 52.4, 75.3, 82.1, and 63.2 
g/m \3\, then the annual mean is:

x = (1/4) x (52.4=75.3=82.1=63.2) = 68.25 or 68.3.

    4.2 Adjustments for Non-scheduled Sampling Days. (a) An adjustment 
in the calculation of the annual mean is needed if sampling is performed 
on days in addition to the days specified by the systematic sampling 
schedule. For the same reasons given in the discussion of estimated 
exceedances, under section 3.2 of this appendix, the quarterly averages 
would be calculated by using the following equation:

                               Equation 6
[GRAPHIC] [TIFF OMITTED] TR18JY97.185

where:

xq = the quarterly mean concentration for quarter q, q=1, 2, 
3, or 4;
xij = the ith concentration value recorded in stratum j;
kj = the number of actual samples in stratum j; and
mq = the number of strata with data in the quarter.

    (b) If one sample value is recorded in each stratum, Equation 6 
reduces to a simple arithmetic average of the observed values as 
described by Equation 4.

                                Example 5

    a. During one calendar quarter, 9 observations were recorded. These 
samples were distributed among 7 sampling strata, with 3 observations in 
one stratum. The concentrations of the 3 observations in the single 
stratum were 202, 242, and 180 g/m\3\. The remaining 6 observed 
concentrations were 55, 68, 73, 92, 120, and 155 g/m\3\. 
Applying the weighting factors specified in Equation 6, the quarterly 
mean is:

xq = (1/7)  x  [(1/3)  x  (202 = 242 = 180) = 155 = 68 = 73 = 
92 = 120 = 155] = 110.1

    b. Although 24-hour measurements are rounded to the nearest 10 
g/m\3\ for determinations of exceedances of the 24-hour 
standard, note that these values are rounded to the nearest 1 
g/m\3\ for the calculation of means.

[62 FR 38712, July 18, 1997]

 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 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.
    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

[[Page 75]]

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 (g/m3).
    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 
g/m3, based on noted mass changes in field blanks in 
conjunction with the 24 m3 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 g/
m3 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 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

[[Page 76]]

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 m as measured by ASTM F 316-94.
    6.5 Filter thickness. 30 to 50 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 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 m particles at the 
sampler's operating face velocity.
    6.9 Filter weight stability. Filter weight loss shall be less than 
20 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 
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 
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 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

[[Page 77]]

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 Impactor.
    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. Tetramethyltetraphenyltrisiloxane, 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/cm3 at 25  deg.C.
    (e) Quantity. 1 mL 0.1 mL.
    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. 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

[[Page 78]]

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/ft2 (1.08 mg/cm2) 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 m3/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, 
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

[[Page 79]]

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 m3.
    (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 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

[[Page 80]]

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.
    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.

[[Page 81]]

    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.
    (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

[[Page 82]]

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 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

[[Page 83]]

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--Summary of Information To Be Provided By the Sampler
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Availability                                        Format
                                    Appendix L section -------------------------------------------------------------------------------------------------
    Information to be provided          reference                        End of        Visual
                                                          Anytime1       period2      display3    Data output4    Digital reading5          Units
--------------------------------------------------------------------------------------------------------------------------------------------------------
Flow rate, 30-second maximum       7.4.5.1............         ............                   *   XX.X...............  L/min
 interval.
Flow rate, average for the sample  7.4.5.2............            *                    *          XX.X...............  L/min
 period.
Flow rate, CV, for sample period.  7.4.5.2............            *                    *     XX.X...............  %
Flow rate, 5-min. average out of   7.4.5.2............                         On/Off.............  ...................
 spec. (FLAG6).
Sample volume, total.............  7.4.5.2............            *                   XX.X...............  m3
Temperature, ambient, 30-second    7.4.8..............         ............         ............  XX.X...............    deg.C
 interval.
Temperature, ambient, min., max.,  7.4.8..............            *                   XX.X...............    deg.C
 average for the sample period.
Baro pressure, ambient, 30-second  7.4.9..............         ............         ............  XXX................  mm Hg
 interval.
Baro pressure, ambient, min.,      7.4.9..............            *                   XXX................  mm Hg
 max., average for the sample
 period.
Filter temperature, 30-second      7.4.11.............         ............         ............  XX.X...............    deg.C
 interval.
Filter temperature differential,   7.4.11.............            *                   On/Off.............  ...................
 30-second interval, out of spec.
 (FLAG6).
Filter temperature, maximum        7.4.11.............            *             *             *             *   X.X, YY/MM/DD HH:mm    deg.C, Yr./Mon./
 differential from ambient, date,                                                                                                     Day Hrs. min
 time of occurrence.
Date and time....................  7.4.12.............         ............         ............  YY/MM/DD HH:mm.....  Yr./Mon./Day Hrs.
                                                                                                                                      min
Sample start and stop time         7.4.12.............                              YY/MM/DD HH:mm.....  Yr./Mon./Day Hrs.
 settings.                                                                                                                            min
Sample period start time.........  7.4.12.............  ............                  YYYY/MM/DD HH:mm...  Yr./Mon./Day Hrs.
                                                                                                                                      min
Elapsed sample time..............  7.4.13.............            *                   HH:mm..............  Hrs. min
Elapsed sample time, out of spec.  7.4.13.............  ............                  On/Off.............  ...................
 (FLAG6).

[[Page 84]]

 
Power interruptions 1 min., start  7.4.15.5...........            *                    *          1HH:mm, 2HH:mm, etc  Hrs. min
 time of first 10.                                                                                               ....
User-entered information, such as  7.4.16.............                         As entered.........  ...................
 sampler and site identification.
--------------------------------------------------------------------------------------------------------------------------------------------------------
 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.
 Indicates that this information is also required to be provided to the AIRS data bank; see Sec.  Sec.  58.26 and 58.35 of this chapter.
 
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 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 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 4  deg.C or less during the entire 
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.

[[Page 85]]

    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 (Qa), 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 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

[[Page 86]]

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 96 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 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 m3 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. 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

[[Page 87]]

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, g/
m3;
Wf, Wi = final and initial weights, respectively, 
of the filter used to collect the PM2.5 particle sample, 
g;
Va = total air volume sampled in actual volume units, as 
provided by the sampler, m3.

    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. Copies of section 2.12 of the Quality Assurance Handbook for Air 
Pollution Measurement Systems, Volume II, Ambient Air Specific Methods, 
EPA/600/R-94/038b, are available from Department E (MD-77B), U.S. EPA, 
Research Triangle Park, NC 27711.
    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]

    Appendix M 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 of section 
12.0 of this appendix.
    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, measured at the actual 
ambient temperature and pressure, 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 actual cubic meter (g/
m3).
    2.3 A method based on this principle will be considered a reference 
method only if the associated sampler meets the requirements specified 
in this appendix and the requirements in part 53 of this chapter, and 
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 
g/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 g/
m\3\ for PM10 concentrations below 80 g/m\3\ and 7 
percent for PM10 concentrations above 80 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 for an ideal sampler whose 
sampling effectiveness is explicitly specified. Also, the particle size 
for 50 percent sampling effectiveness is required to be 
100.5 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

[[Page 119]]

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 of this appendix, 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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 of this 
appendix 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 of this 
appendix.
    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, under section 7.1.3 of this appendix, 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, under section 7.1.5 
of this appendix, 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 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

[[Page 120]]

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 m particles at the sampler's 
operating face velocity.
    7.2.3 Integrity. 5 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 of section 12.0 of this appendix 
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 Institute of Standard and Technology (NIST). 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).
    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 rate indicator employed. Calibration is in terms of 
actual volumetric flow rates (Qa) to meet the requirements of 
section 8.1 of this appendix. The general procedure given here serves to 
illustrate the steps involved in the calibration. Consult the sampler 
manufacturer's instruction manual and reference 2 of section 12.0 of 
this appendix for specific guidance on calibration. Reference 14 of 
section 12.0 of this appendix provides additional information on various 
other 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 NIST. 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 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, under 
section 7.1.2 of the appendix, 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

[[Page 121]]

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 in section 
12.0 of this appendix 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 in section 12.0 of this appendix. 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 (a) 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.
    (b) 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, under section 8.2.4 of this appendix. 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 241 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, in 
note following section 9.6 of this appendix.
    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 section 9.3 of this 
appendix).
    9.17 Immediately after equilibration, reweigh the filter and record 
the postsampling weight with the filter identification number.
    10.0 Sampler Maintenance.
    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 total volume of air sampled as:

V = Qat

where:

V = total air sampled, at ambient temperature and 
pressure,m3;
Qa = average sample flow rate at ambient temperature and 
pressure, m3/min; and
t = sampling time, min.
    11.2 (a) Calculate the PM10 concentration as:

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

where:


[[Page 122]]


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

    (b) 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 [(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.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.

[62 FR 38753, July 18, 1997]

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

    1.0 General.
    (a) This appendix explains the data handling conventions and 
computations necessary for determining when the annual and 24-hour 
primary and secondary national ambient air quality standards for PM 
specified in Sec. 50.7 of this chapter are met. Particulate matter is 
measured in the ambient air as PM10 and PM2.5 
(particles with an aerodynamic diameter less than or equal to a nominal 
10 and 2.5 micrometers, respectively) by a reference method based on 
appendix M of this part for PM10 and on appendix L of this 
part for PM2.5, 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 handling and computation 
procedures to be used in making comparisons between reported 
PM10 and PM2.5 concentrations and the levels of 
the PM standards are specified in the following sections.
    (b) Data resulting from uncontrollable or natural events, for 
example structural fires or high winds, may require special 
consideration. In some cases, it may be appropriate to exclude these 
data because they could result in inappropriate values to compare with 
the levels of the PM standards. In other cases, it may be more 
appropriate to retain the data for comparison with the level of the PM 
standards and then allow the EPA to formulate the appropriate regulatory 
response. Whether to exclude, retain, or make adjustments to the data 
affected by uncontrollable or natural events is subject to the approval 
of the appropriate Regional Administrator.
    (c) The terms used in this appendix are defined as follows:
    Average and mean refer to an arithmetic mean.
    Daily value for PM refers to the 24-hour average concentration of PM 
calculated or measured from midnight to midnight (local time) for 
PM10 or PM2.5.
    Designated monitors are those monitoring sites designated in a State 
PM Monitoring Network Description for spatial averaging in areas opting 
for spatial averaging in accordance with part 58 of this chapter.

[[Page 123]]

    98th percentile (used for PM2.5) means the 
daily value out of a year of monitoring data below which 98 percent of 
all values in the group fall.
    99th percentile (used for PM10) means the 
daily value out of a year of monitoring data below which 99 percent of 
all values in the group fall.
    Year refers to a calendar year.
    (d) Sections 2.1 and 2.5 of this appendix contain data handling 
instructions for the option of using a spatially averaged network of 
monitors for the annual standard. If spatial averaging is not considered 
for an area, then the spatial average is equivalent to the annual 
average of a single site and is treated accordingly in subsequent 
calculations. For example, paragraph (a)(3) of section 2.1 of this 
appendix could be eliminated since the spatial average would be 
equivalent to the annual average.
    2.0 Comparisons with the PM2.5 Standards.
    2.1 Annual PM2.5 Standard.
    (a) The annual PM2.5 standard is met when the 3-year 
average of the spatially averaged annual means is less than or equal to 
15.0 g/m3. The 3-year average of the spatially 
averaged annual means is determined by averaging quarterly means at each 
monitor to obtain the annual mean PM2.5 concentrations at 
each monitor, then averaging across all designated monitors, and finally 
averaging for 3 consecutive years. The steps can be summarized as 
follows:
    (1) Average 24-hour measurements to obtain quarterly means at each 
monitor.
    (2) Average quarterly means to obtain annual means at each monitor.
    (3) Average across designated monitoring sites to obtain an annual 
spatial mean for an area (this can be one site in which case the spatial 
mean is equal to the annual mean).
    (4) Average 3 years of annual spatial means to obtain a 3-year 
average of spatially averaged annual means.
    (b) In the case of spatial averaging, 3 years of spatial averages 
are required to demonstrate that the standard has been met. Designated 
sites with less than 3 years of data shall be included in spatial 
averages for those years that data completeness requirements are met. 
For the annual PM2.5 standard, a year meets data completeness 
requirements when at least 75 percent of the scheduled sampling days for 
each quarter have valid data. However, years with high concentrations 
and more than a minimal amount of data (at least 11 samples in each 
quarter) shall not be ignored just because they are comprised of 
quarters with less than complete data. Thus, in computing annual 
spatially averaged means, years containing quarters with at least 11 
samples but less than 75 percent data completeness shall be included in 
the computation if the resulting spatially averaged annual mean 
concentration (rounded according to the conventions of section 2.3 of 
this appendix) is greater than the level of the standard.
    (c) Situations may arise in which there are compelling reasons to 
retain years containing quarters which do not meet the data completeness 
requirement of 75 percent or the minimum number of 11 samples. The use 
of less than complete data is subject to the approval of the appropriate 
Regional Administrator.
    (d) The equations for calculating the 3-year average annual mean of 
the PM2.5 standard are given in section 2.5 of this appendix.
    2.2 24-Hour PM2.5 Standard.
    (a) The 24-hour PM2.5 standard is met when the 3-year 
average of the 98th percentile values at each monitoring site 
is less than or equal to 65 g/m3. This comparison 
shall be based on 3 consecutive, complete years of air quality data. A 
year meets data completeness requirements when at least 75 percent of 
the scheduled sampling days for each quarter have valid data. However, 
years with high concentrations shall not be ignored just because they 
are comprised of quarters with less than complete data. Thus, in 
computing the 3-year average 98th percentile value, years 
containing quarters with less than 75 percent data completeness shall be 
included in the computation if the annual 98th percentile 
value (rounded according to the conventions of section 2.3 of this 
appendix) is greater than the level of the standard.
    (b) Situations may arise in which there are compelling reasons to 
retain years containing quarters which do not meet the data completeness 
requirement. The use of less than complete data is subject to the 
approval of the appropriate Regional Administrator.
    (c) The equations for calculating the 3-year average of the annual 
98th percentile values is given in section 2.6 of this 
appendix.
    2.3 Rounding Conventions. For the purposes of comparing calculated 
values to the applicable level of the standard, it is necessary to round 
the final results of the calculations described in sections 2.5 and 2.6 
of this appendix. For the annual PM2.5 standard, the 3-year 
average of the spatially averaged annual means shall be rounded to the 
nearest 0.1 g/m3 (decimals 0.05 and greater are 
rounded up to the next 0.1, and any decimal lower than 0.05 is rounded 
down to the nearest 0.1). For the 24-hour PM2.5 standard, the 
3-year average of the annual 98th percentile values shall be 
rounded to the nearest 1 g/m3 (decimals 0.5 and 
greater are rounded up to nearest whole number, and any decimal lower 
than 0.5 is rounded down to the nearest whole number).
    2.4 Monitoring Considerations.
    (a) Section 58.13 of this chapter specifies the required minimum 
frequency of sampling

[[Page 124]]

for PM2.5. Exceptions to the specified sampling frequencies, 
such as a reduced frequency during a season of expected low 
concentrations, are subject to the approval of the appropriate Regional 
Administrator. Section 58.14 of 40 CFR part 58 and section 2.8 of 
appendix D of 40 CFR part 58, specify which monitors are eligible for 
making comparisons with the PM standards. In determining a spatial mean 
using two or more monitoring sites operating in a given year, the annual 
mean for an individual site may be included in the spatial mean if and 
only if the mean for that site meets the criterion specified in Sec. 2.8 
of appendix D of 40 CFR part 58. In the event data from an otherwise 
eligible site is excluded from being averaged with data from other sites 
on the basis of this criterion, then the 3-year mean from that site 
shall be compared directly to the annual standard.
    (b) For the annual PM2.5 standard, when designated 
monitors are located at the same site and are reporting PM2.5 
values for the same time periods, and when spatial averaging has been 
chosen, their concentrations shall be averaged before an area-wide 
spatial average is calculated. Such monitors will then be considered as 
one monitor.
    2.5 Equations for the Annual PM2.5 Standard.
    (a) An annual mean value for PM2.5 is determined by first 
averaging the daily values of a calendar quarter:

                               Equation 1
[GRAPHIC] [TIFF OMITTED] TR18JY97.000

where:

xq,y,s = the mean for quarter q of year y for site s;
nq = the number of monitored values in the quarter; and
xi,q,y,s = the ith value in quarter q for year y 
for site s.

    (b) The following equation is then to be used for calculation of the 
annual mean:

                               Equation 2
[GRAPHIC] [TIFF OMITTED] TR18JY97.001

where:

xy,s = the annual mean concentration for year y (y = 1, 2, or 
3) and for site s; and
xq,y,s = the mean for quarter q of year y for site s.

    (c)(1) The spatially averaged annual mean for year y is computed by 
first calculating the annual mean for each site designated to be 
included in a spatial average, xy,s, and then computing the 
average of these values across sites:

                               Equation 3
[GRAPHIC] [TIFF OMITTED] TR18JY97.002

where:

xy = the spatially averaged mean for year y;
xy,s = the annual mean for year y and site s; and
ns = the number of sites designated to be averaged.

    (2) In the event that an area designated for spatial averaging has 
two or more sites at the same location producing data for the same time 
periods, the sites are averaged together before using Equation 3 by:

                               Equation 4
[GRAPHIC] [TIFF OMITTED] TR18JY97.003

where:

xy,s* = the annual mean for year y for the sites at the same 
location (which will now be considered one site);
nc = the number of sites at the same location designated to 
be included in the spatial average; and
xy,s = the annual mean for year y and site s.

    (d) The 3-year average of the spatially averaged annual means is 
calculated by using the following equation:

                               Equation 5
[GRAPHIC] [TIFF OMITTED] TR18JY97.004

where:

x = the 3-year average of the spatially averaged annual means; and
xy = the spatially averaged annual mean for year y.

Example 1--Area Designated for Spatial Averaging That Meets the Primary 
                    Annual PM2.5 Standard.

    a. In an area designated for spatial averaging, four designated 
monitors recorded data in at least 1 year of a particular 3-year period. 
Using Equations 1 and 2, the annual means for PM2.5 at each 
site are calculated for each year. The following table can be created 
from the results. Data completeness percentages for the quarter with the 
fewest number of samples are also shown.

[[Page 125]]



                                                         Table 1--Results from Equations 1 and 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                       Site 1        Site 2        Site 3        Site 4
                                                                                                                                            Spatial mean
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 1.........................................  Annual mean (g/m\3\)....          12.7  ............  ............  ............         12.7
                                                 % data completeness..............          80             0             0             0    ............
Year 2.........................................  Annual mean (g/m\3\)....          12.6          17.5          15.2  ............         15.05
                                                 % data completeness..............          90            63            38             0    ............
Year 3.........................................  Annual mean (g/m\3\)....          12.5          18.5          14.1          16.9         15.50
                                                 % data completeness..............          90            80            85            50    ............
3-year mean....................................  .................................  ............  ............  ............  ............         14.42
--------------------------------------------------------------------------------------------------------------------------------------------------------

    b. The data from these sites are averaged in the order described in 
section 2.1 of this appendix. Note that the annual mean from site 3 in 
year 2 and the annual mean from site 4 in year 3 do not meet the 75 
percent data completeness criteria. Assuming the 38 percent data 
completeness represents a quarter with fewer than 11 samples, site 3 in 
year 2 does not meet the minimum data completeness requirement of 11 
samples in each quarter. The site is therefore excluded from the 
calculation of the spatial mean for year 2. However, since the spatial 
mean for year 3 is above the level of the standard and the minimum data 
requirement of 11 samples in each quarter has been met, the annual mean 
from site 4 in year 3 is included in the calculation of the spatial 
mean for year 3 and in the calculation of the 3-year average. The 3-year 
average is rounded to 14.4 g/m3, indicating that 
this area meets the annual PM2.5 standard.

 Example 2--Area With Two Monitors at the Same Location That Meets the 
                Primary Annual PM2.5 Standard.

    a. In an area designated for spatial averaging, six designated 
monitors, with two monitors at the same location (5 and 6), recorded 
data in a particular 3-year period. Using Equations 1 and 2, the annual 
means for PM2.5 are calculated for each year. The following 
table can be created from the results.

                                                         Table 2--Results From Equations 1 and 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                Average of 5
                                               Site 1        Site 2        Site 3        Site 4        Site 5        Site 6         and 6       Spatial
       Annual mean (g/m\3\)                                                                                                             mean
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 1....................................          12.9           9.9          12.6          11.1          14.5          14.6        14.55        12.21
Year 2....................................          14.5          13.3          12.2          10.9          16.1          16.0        16.05        13.39
Year 3....................................          14.4          12.4          11.5           9.7          12.3          12.1        12.20        12.04
3-Year mean...............................  ............  ............  ............  ............  ............  ............  ............       12.55
--------------------------------------------------------------------------------------------------------------------------------------------------------

    b. The annual means for sites 5 and 6 are averaged together using 
Equation 4 before the spatial average is calculated using Equation 3 
since they are in the same location. The 3-year mean is rounded to 12.6 
g/m3, indicating that this area meets the annual 
PM2.5 standard.

  Example 3--Area With a Single Monitor That Meets the Primary Annual 
                       PM2.5 Standard.

    a. Given data from a single monitor in an area, the calculations are 
as follows. Using Equations 1 and 2, the annual means for 
PM2.5 are calculated for each year. If the annual means are 
10.28, 17.38, and 12.25 g/m3, then the 3-year mean 
is:
[GRAPHIC] [TIFF OMITTED] TR18JY97.005

    b. This value is rounded to 13.3, indicating that this area meets 
the annual PM2.5 standard.
    2.6 Equations for the 24-Hour PM2.5 Standard.
    (a) When the data for a particular site and year meet the data 
completeness requirements in section 2.2 of this appendix, calculation 
of the 98th percentile is accomplished by the following 
steps. All the daily values from a particular site and year comprise a 
series of values (x1, x2, x3, ..., 
xn), that can be sorted into a series where each number is 
equal to or larger than the preceding number (x[1], 
x[2], x[3], ..., x[n]). In this case, 
x[1] is the smallest number and x[n] is the 
largest value. The 98th percentile is found from the

[[Page 126]]

sorted series of daily values which is ordered from the lowest to the 
highest number. Compute (0.98)  x  (n) as the number ``i.d'', where 
``i'' is the integer part of the result and ``d'' is the decimal part of 
the result. The 98th percentile value for year y, 
P0.98, y, is given by Equation 6:

                               Equation 6
[GRAPHIC] [TIFF OMITTED] TR18JY97.006

where:

P0.98,y = 98th percentile for year y;
x[i=1] = the (i=1)th number in the ordered series 
of numbers; and
i = the integer part of the product of 0.98 and n.

    (b) The 3-year average 98th percentile is then calculated 
by averaging the annual 98th percentiles:

                               Equation 7
[GRAPHIC] [TIFF OMITTED] TR18JY97.007

    (c) The 3-year average 98th percentile is rounded 
according to the conventions in section 2.3 of this appendix before a 
comparison with the standard is made.

 Example 4--Ambient Monitoring Site With Every-Day Sampling That Meets 
             the Primary 24-Hour PM2.5 Standard.

    a. In each year of a particular 3 year period, varying numbers of 
daily PM2.5 values (e.g., 281, 304, and 296) out of a 
possible 365 values were recorded at a particular site with the 
following ranked values (in g/m3):

                                  Table 3--Ordered Monitoring Data For 3 Years
----------------------------------------------------------------------------------------------------------------
               Year 1                                Year 2                                Year 3
----------------------------------------------------------------------------------------------------------------
      j rank            Xj value            j rank            Xj value            j rank            Xj value
----------------------------------------------------------------------------------------------------------------
275..............            57.9                296               54.3                290               66.0
276..............            59.0                297               57.1                291               68.4
277..............            62.2                298               63.0                292               69.8
----------------------------------------------------------------------------------------------------------------

    b. Using Equation 6, the 98th percentile values for each 
year are calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR18JY97.008

[GRAPHIC] [TIFF OMITTED] TR18JY97.009

[GRAPHIC] [TIFF OMITTED] TR18JY97.010

    c.1. Using Equation 7, the 3-year average 98th percentile 
is calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR18JY97.011

    2. Therefore, this site meets the 24-hour PM2.5 standard.
    3.0 Comparisons with the PM10 Standards.
    3.1 Annual PM10 Standard.
    (a) The annual PM10 standard is met when the 3-year 
average of the annual mean PM10 concentrations at each 
monitoring site is less than or equal to 50 g/m3. 
The 3-year average of the annual means is determined by averaging 
quarterly means to obtain annual mean PM10 concentrations for 
3 consecutive, complete years at each monitoring site. The steps can be 
summarized as follows:
    (1) Average 24-hour measurements to obtain a quarterly mean.

[[Page 127]]

    (2) Average quarterly means to obtain an annual mean.
    (3) Average annual means to obtain a 3-year mean.
    (b) For the annual PM10 standard, a year meets data 
completeness requirements when at least 75 percent of the scheduled 
sampling days for each quarter have valid data. However, years with high 
concentrations and more than a minimal amount of data (at least 11 
samples in each quarter) shall not be ignored just because they are 
comprised of quarters with less than complete data. Thus, in computing 
the 3-year average annual mean concentration, years containing quarters 
with at least 11 samples but less than 75 percent data completeness 
shall be included in the computation if the annual mean concentration 
(rounded according to the conventions of section 2.3 of this appendix) 
is greater than the level of the standard.
    (c) Situations may arise in which there are compelling reasons to 
retain years containing quarters which do not meet the data completeness 
requirement of 75 percent or the minimum number of 11 samples. The use 
of less than complete data is subject to the approval of the appropriate 
Regional Administrator.
    (d) The equations for calculating the 3-year average annual mean of 
the PM10 standard are given in section 3.5 of this appendix.
    3.2 24-Hour PM10 Standard.
    (a) The 24-hour PM10 standard is met when the 3-year 
average of the annual 99th percentile values at each 
monitoring site is less than or equal to 150 g/m3. 
This comparison shall be based on 3 consecutive, complete years of air 
quality data. A year meets data completeness requirements when at least 
75 percent of the scheduled sampling days for each quarter have valid 
data. However, years with high concentrations shall not be ignored just 
because they are comprised of quarters with less than complete data. 
Thus, in computing the 3-year average of the annual 99th 
percentile values, years containing quarters with less than 75 percent 
data completeness shall be included in the computation if the annual 
99th percentile value (rounded according to the conventions 
of section 2.3 of this appendix) is greater than the level of the 
standard.
    (b) Situations may arise in which there are compelling reasons to 
retain years containing quarters which do not meet the data completeness 
requirement. The use of less than complete data is subject to the 
approval of the appropriate Regional Administrator.
    (c) The equation for calculating the 3-year average of the annual 
99th percentile values is given in section 2.6 of this 
appendix.
    3.3 Rounding Conventions. For the annual PM10 standard, 
the 3-year average of the annual PM10 means shall be rounded 
to the nearest 1 g/m3 (decimals 0.5 and greater are 
rounded up to the next whole number, and any decimal less than 0.5 is 
rounded down to the nearest whole number). For the 24-hour 
PM10 standard, the 3-year average of the annual 
99th percentile values of PM10 shall be rounded to 
the nearest 10 g/m3 (155 g/m3 
and greater would be rounded to 160 g/m3 and 154 
g/m3 and less would be rounded to 150 g/
m3).
    3.4 Monitoring Considerations. Section 58.13 of this chapter 
specifies the required minimum frequency of sampling for 
PM10. Exceptions to the specified sampling frequencies, such 
as a reduced frequency during a season of expected low concentrations, 
are subject to the approval of the appropriate Regional Administrator. 
For making comparisons with the PM10 NAAQS, all sites meeting 
applicable requirements in part 58 of this chapter would be used.
    3.5 Equations for the Annual PM10 Standard.
    (a) An annual arithmetic mean value for PM10 is 
determined by first averaging the 24-hour values of a calendar quarter 
using the following equation:

                               Equation 8
[GRAPHIC] [TIFF OMITTED] TR18JY97.012

where:

xq,y = the mean for quarter q of year y;
nq = the number of monitored values in the quarter; and
xi,q,y = the ith value in quarter q for year y.

    (b) The following equation is then to be used for calculation of the 
annual mean:

                               Equation 9
[GRAPHIC] [TIFF OMITTED] TR18JY97.013

where:

xy = the annual mean concentration for year y, (y=1, 2, or 
3); and
xq,y = the mean for a quarter q of year y.

    (c) The 3-year average of the annual means is calculated by using 
the following equation:

                               Equation 10
[GRAPHIC] [TIFF OMITTED] TR18JY97.014

where:

x = the 3-year average of the annual means; and

xy = the annual mean for calendar year y.


[[Page 128]]



    Example 5--Ambient Monitoring Site That Does Not Meet the Annual 
                        PM10 Standard.

    a. Given data from a PM10 monitor and using Equations 8 
and 9, the annual means for PM10 are calculated for each 
year. If the annual means are 52.42, 82.17, and 63.23 g/
m3, then the 3-year average annual mean is:
[GRAPHIC] [TIFF OMITTED] TR18JY97.015

    b. Therefore, this site does not meet the annual PM10 
standard.
    3.6 Equation for the 24-Hour PM10 Standard.
    (a) When the data for a particular site and year meet the data 
completeness requirements in section 3.2 of this appendix, calculation 
of the 99th percentile is accomplished by the following 
steps. All the daily values from a particular site and year comprise a 
series of values (x1, x2, x3, ..., 
xn) that can be sorted into a series where each number is 
equal to or larger than the preceding number (x[1], 
x[2], x[3], ..., x[n]). In this case, 
x[1] is the smallest number and x[n] is the largest value. 
The 99th percentile is found from the sorted series of daily 
values which is ordered from the lowest to the highest number. Compute 
(0.99)  x  (n) as the number ``i.d'', where ``i'' is the integer part of 
the result and ``d'' is the decimal part of the result. The 
99th percentile value for year y, P0.99,y, is 
given by Equation 11:

                               Equation 11
[GRAPHIC] [TIFF OMITTED] TR18JY97.016

where:

P0.99,y = the 99th percentile for year y;

x[i=1] = the (i=1)th number in the ordered series 
of numbers; and

i = the integer part of the product of 0.99 and n.

    (b) The 3-year average 99th percentile value is then 
calculated by averaging the annual 99th percentiles:

                               Equation 12
[GRAPHIC] [TIFF OMITTED] TR18JY97.017

    (c) The 3-year average 99th percentile is rounded 
according to the conventions in section 3.3 of this appendix before a 
comparison with the standard is made.

 Example 6--Ambient Monitoring Site With Sampling Every Sixth Day That 
           Meets the Primary 24-Hour PM10 Standard.

    a. In each year of a particular 3 year period, varying numbers of 
PM10 daily values (e.g., 110, 98, and 100) out of a possible 
121 daily values were recorded at a particular site with the following 
ranked values (in g/m3):

                                  Table 4--Ordered Monitoring Data For 3 Years
----------------------------------------------------------------------------------------------------------------
               Year 1                                Year 2                                Year 3
----------------------------------------------------------------------------------------------------------------
      j rank            Xj value            j rank            Xj value            j rank            Xj value
----------------------------------------------------------------------------------------------------------------
108..............             120                 96                143                 98                140
109..............             128                 97                148                 99                144
110..............             130                 98                150                100                147
----------------------------------------------------------------------------------------------------------------

    b. Using Equation 11, the 99th percentile values for each 
year are calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR18JY97.018


[GRAPHIC] [TIFF OMITTED] TR18JY97.019



[[Page 129]]


[GRAPHIC] [TIFF OMITTED] TR18JY97.020

    c. 1. Using Equation 12, the 3-year average 99th 
percentile is calculated as follows:
[GRAPHIC] [TIFF OMITTED] TR18JY97.021

    2. Therefore, this site meets the 24-hour PM10 standard.

[62 FR 38755, July 18, 1997]



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




Subparts A-E [Reserved]

                   Subpart F--Procedural Requirements

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

        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.

                     Subpart K--Source Survelliance

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]

[[Page 130]]

                     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.

                   Subpart P--Protection of Visibility

51.300  Purpose and applicability.
51.301  Definitions.
51.302  Implementation control strategies for 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  Long-term strategy requirements for reasonably attributable 
          visibility impairment.
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--Calibrations, Adjustments and Quality Control
Appendix B to Subpart S--Test Procedures
Appendix C to Subpart S--Steady-State Short Test Standards
Appendix D to Subpart S--Steady-State Short Test Equipment
Appendix E to Subpart S--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.

                 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  Prohibition.
51.851  State Implementation Plan (SIP) revision.
51.852  Definitions.
51.853  Applicability.
51.854  Conformity analysis.
51.855  Reporting requirements.
51.856  Public participation.
51.857  Frequency of conformity determinations.

[[Page 131]]

51.858  Criteria for determining conformity of general Federal actions.
51.859  Procedures for conformity determinations of general Federal 
          actions.
51.860  Mitigation of air quality impacts.

Appendixes A-K [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 [Reserved]
Appendix P to Part 51--Minimum Emission Monitoring Requirements
Appendixes Q-R [Reserved]
Appendix S to Part 51--Emission Offset Interpretative Ruling
Appendixes T-U [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

    Authority: 42 U.S.C. 7410, 7414, 7421, 7470-7479, 7491, 7492, 7601, 
and 7602.

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

Subparts A-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 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

[[Page 132]]

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.
    (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

[[Page 133]]

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); 
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); 2-
(ethoxydifluoromethyl)-1,1,1,2,3,3,3-heptafluoropropane 
((CF3)2CFCF2OC2H5)
; methyl acetate and perfluorocarbon compounds which fall into these 
classes:
    (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.
    (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

[[Page 134]]

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.
    (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;

[[Page 135]]

    (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:
    (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

[[Page 136]]

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.
    (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, as amended at 52 FR 24712, July 1, 1987; 57 
FR 3945, Feb. 3, 1992; 61 FR 4590, Feb. 7, 1996; 61 FR 16060, Apr. 11, 
1996; 61 FR 30162, June 14, 1996; 61 FR 52850, Oct. 8, 1996; 62 FR 
44903, Aug. 25, 1997; 63 FR 9151, Feb. 24, 1998; 63 FR 17333, Apr. 9, 
1998]



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

[[Page 137]]

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, 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, 
States must conduct one or more public hearings on the following prior 
to 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 Secs. 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.
    (6) In the case of hearings on AQMA plans:
    (i) Notification to the chief executives of affected local 
governments, planning agencies, transportation agencies, environmental 
control agencies, economic development agencies, and any other affected 
States, and
    (ii) Public notice of alternative analysis and plan development 
procedures approved under Sec. 51.63.
    (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 hearing required by paragraph (a) of this section 
was held in accordance with the notice required by paragraph (d) of this 
section.

[[Page 138]]

    (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.



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 five copies of the plan to the appropriate Regional 
Office, with a letter giving notice of such action.
    (b) Upon request of a State, the Administrator will provide 
preliminary review of a plan or portion thereof submitted in advance of 
the date such plan is due. Such requests must be made in writing to the 
appropriate Regional Office and must be accompanied by five copies of 
the materials to be reviewed. Requests for preliminary review do not 
relieve a State of the responsibility of adopting and submitting plans 
in accordance with prescribed due dates.

[51 FR 40661, Nov. 7, 1986, as amended at 55 FR 5830, Feb. 16, 1990; 63 
FR 9151, Feb. 24, 1998]



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]



                       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]

[[Page 139]]



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.
    (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.

[[Page 140]]



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 Secs. 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 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 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

[[Page 141]]

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 lead emissions inventory is based must contain 
all sources that emit five 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]



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 
Secs. 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:
    (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

[[Page 142]]

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 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)

[[Page 143]]

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 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

[[Page 144]]

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 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

[[Page 145]]

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 oxides of nitrogen.

    (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) Under section 110(a)(1) of the CAA, 42 U.S.C. 7410(a)(1), the 
Administrator determines that each jurisdiction listed in paragraph (c) 
of this section must submit a SIP revision to comply with the 
requirements of section 110(a)(2)(D)(i)(I), 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.
    (b)(1) For each jurisdiction listed 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:
    (i) Contains control measures adequate to prohibit emissions of 
NOX that would otherwise be projected, in accordance with 
paragraph (g) of this section, to cause the jurisdiction's overall 
NOX emissions to be in excess of the budget for that 
jurisdiction described in paragraph (e) of this section (except as 
provided in paragraph (b)(2) of this section),
    (ii) Requires full implementation of all such control measures by no 
later than May 1, 2003, 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 
budget for purposes of this section.
    (2) The requirements of paragraph (b)(1)(i) of this section shall be 
deemed satisfied, for the portion of the budget covered by an interstate 
trading program, if the SIP revision:
    (i) Contains provisions for an interstate trading program that EPA 
determines will, in conjunction with interstate trading programs for one 
or more other jurisdictions, prohibit NOX emissions in excess 
of the sum of the portion of the budgets covered by the trading programs 
for those jurisdictions; and
    (ii) Conforms to the following criteria:
    (A) Emissions reductions used to demonstrate compliance with the 
revision must occur during the ozone season.
    (B) Emissions reductions occurring prior to the year 2003 may be 
used by a source to demonstrate compliance with the SIP revision for the 
2003 and 2004 ozone seasons, provided the SIP's provisions regarding 
such use comply with the requirements of paragraph (e)(3) of this 
section.
    (C) Emissions reduction credits or emissions allowances held by a 
source or other person following the 2003 ozone season or any ozone 
season thereafter that are not required to demonstrate compliance with 
the SIP for the relevant ozone season may be banked and used to 
demonstrate compliance with the SIP in a subsequent ozone season.
    (D) Early reductions created according to the provisions in 
paragraph (b)(2)(ii)(B) of this section and used in the 2003 ozone 
season are not subject to the flow control provisions set forth in 
paragraph (b)(2)(ii)(E) of this section.

[[Page 146]]

    (E) Starting with the 2004 ozone season, the SIP shall include 
provisions to limit the use of banked emissions reduction credits or 
emissions allowances beyond a predetermined amount as calculated by one 
of the following approaches:
    (1) Following the determination of compliance after each ozone 
season, if the total number of emissions reduction credits or banked 
allowances held by sources or other persons subject to the trading 
program exceeds 10 percent of the sum of the allowable ozone season 
NOX emissions for all sources subject to the trading program, 
then all banked allowances used for compliance for the following ozone 
season shall be subject to the following:
    (i) A ratio will be established according to the following formula: 
(0.10)  x  (the sum of the allowable ozone season NOX 
emissions for all sources subject to the trading program)  (the 
total number of banked emissions reduction credits or emissions 
allowances held by all sources or other persons subject to the trading 
program).
    (ii) The ratio, determined using the formula specified in paragraph 
(b)(2)(ii)(E)(1)(i) of this section, will be multiplied by the number of 
banked emissions reduction credits or emissions allowances held in each 
account at the time of compliance determination. The resulting product 
is the number of banked emissions reduction credits or emissions 
allowances in the account which can be used in the current year's ozone 
season at a rate of 1 credit or allowance for every 1 ton of emissions. 
The SIP shall specify that banked emissions reduction credits or 
emissions allowances in excess of the resulting product either may not 
be used for compliance, or may only be used for compliance at a rate no 
less than 2 credits or allowances for every 1 ton of emissions.
    (2) At the time of compliance determination for each ozone season, 
if the total number of banked emissions reduction credits or emissions 
allowances held by a source subject to the trading program exceeds 10 
percent of the source's allowable ozone season NOX emissions, 
all banked emissions reduction credits or emissions allowances used for 
compliance in such ozone season by the source shall be subject to the 
following:
    (i) The source may use an amount of banked emissions reduction 
credits or emissions allowances not greater than 10 percent of the 
source's allowable ozone season NOX emissions for compliance 
at a rate of 1 credit or allowance for every 1 ton of emissions.
    (ii) The SIP shall specify that banked emissions reduction credits 
or emissions allowances in excess of 10 percent of the source's 
allowable ozone season NOX emissions may not be used for 
compliance, or may only be used for compliance at a rate no less than 2 
credits or allowances for every 1 ton of emissions.
    (c) The following jurisdictions (hereinafter referred to as 
``States'') are subject to the requirements of this section: Alabama, 
Connecticut, Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, 
Massachusetts, Michigan, Missouri, New Jersey, New York, North Carolina, 
Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, 
West Virginia, Wisconsin, and the District of Columbia.
    (d)(1) The SIP submissions required under paragraph (a) of this 
section must be submitted to EPA by no later than September 30, 1999.
    (2) The State makes an official submission of its SIP revision to 
EPA only when:
    (i) The submission conforms to the requirements of appendix V to 
this part; and
    (ii) The State delivers five copies of the plan to the appropriate 
Regional Office, with a letter giving notice of such action.
    (e)(1) The NOX 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) 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) The State-by-State amounts of the NOX budget, 
expressed in tons, are as follows:

------------------------------------------------------------------------
                           State                                Budget
------------------------------------------------------------------------
Alabama....................................................      172,037

[[Page 147]]

 
Connecticut................................................       43,081
Delaware...................................................       22,789
District of Columbia.......................................        6,672
Georgia....................................................      189,634
Illinois...................................................      274,799
Indiana....................................................      238,970
Kentucky...................................................      155,619
Maryland...................................................       81,625
Massachusetts..............................................       85,296
Michigan...................................................      224,582
Missouri...................................................      128,146
New Jersey.................................................      100,133
New York...................................................      240,123
North Carolina.............................................      168,373
Ohio.......................................................      250,930
Pennsylvania...............................................      257,441
Rhode Island...............................................        9,810
South Carolina.............................................      124,211
Tennessee..................................................      197,664
Virginia...................................................      185,027
West Virginia..............................................       91,216
Wisconsin..................................................      136,172
                                                            ------------
    Total..................................................    3,384,350
------------------------------------------------------------------------

    (3)(i) Notwithstanding the State's obligation to comply with the 
budgets set forth in paragraph (e)(2) of this section, a SIP revision 
may allow sources required by the revision to implement NOX 
emission control measures by May 1, 2003 to demonstrate compliance in 
the 2003 and 2004 ozone seasons using credit issued from the State's 
compliance supplement pool, as set forth in paragraph (e)(3)(iii) of 
this section.
    (ii) A source may not use credit from the compliance supplement pool 
to demonstrate compliance after the 2004 ozone season.
    (iii) The State-by-State amounts of the compliance supplement pool 
are as follows:

------------------------------------------------------------------------
                                                              Compliance
                                                              supplement
                           State                              pool (tons
                                                               of NOX)
------------------------------------------------------------------------
Alabama....................................................       11,350
Connecticut................................................          549
Delaware...................................................          127
District of Columbia.......................................            0
Georgia....................................................       11,179
Illinois...................................................       17,586
Indiana....................................................       20,390
Kentucky...................................................       14,495
Maryland...................................................        3,840
Massachusetts..............................................          397
Michigan...................................................       11,103
Missouri...................................................       10,783
New Jersey.................................................        1,479
New York...................................................        2,370
North Carolina.............................................       10,544
Ohio.......................................................       22,320
Pennsylvania...............................................       15,662
Rhode Island...............................................           15
South Carolina.............................................        5,122
Tennessee..................................................       10,557
Virginia...................................................        6,914
West Virginia..............................................       16,410
Wisconsin..................................................        6,808
                                                            ------------
    Total..................................................      200,000
------------------------------------------------------------------------

    (iv) The SIP revision may provide for the distribution of 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 some or all of the compliance supplement 
pool to sources that implement emissions reductions during the ozone 
season beyond all applicable requirements in years prior to the year 
2003 according to the following provisions:
    (1) The State shall complete the issuance process by no later than 
May 1, 2003.
    (2) The emissions reduction may not be required by the State's SIP 
or be otherwise required by the CAA.
    (3) The emissions reduction must be verified by the source as 
actually having occurred during an ozone season between September 30, 
1999 and May 1, 2003.
    (4) The emissions reduction must be quantified according to 
procedures set forth in the SIP revision and approved by EPA. Emissions 
reductions implemented by 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, must be quantified according to the requirements in 
paragraph (i)(4) of this section.
    (5) If the SIP revision contains approved provisions for an 
emissions trading program, sources that receive credit according to the 
requirements of this paragraph may trade the credit to other sources or 
persons according to the provisions in the trading program.
    (B) The State may issue some or all of the compliance supplement 
pool to sources that demonstrate a need for an extension of the May 1, 
2003 compliance deadline according to the following provisions:

[[Page 148]]

    (1) The State shall initiate the issuance process by the later date 
of September 30, 2002 or after the State issues credit according to the 
procedures in paragraph (e)(3)(iv)(A) of this section.
    (2) The State shall complete the issuance process by no later than 
May 1, 2003.
    (3) The State shall issue credit to a source only if the source 
demonstrates the following:
    (i) For a source used to generate electricity, compliance with the 
SIP revision's applicable control measures by May 1, 2003, would create 
undue risk for the reliability of the electricity supply. This 
demonstration must include a showing that it would not be feasible to 
import electricity from other electricity generation systems during the 
installation of control technologies 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 May 1, 2003, would 
create undue risk for the source or its associated industry to a degree 
that is comparable to the risk described in paragraph 
(e)(3)(iv)(B)(3)(i) of this section.
    (iii) For a source subject to an approved SIP revision that allows 
for early reduction credits in accordance with paragraph (e)(3)(iv)(A) 
of this section, it was not possible for the source to comply with 
applicable control measures by generating early reduction credits or 
acquiring early reduction credits from other sources.
    (iv) For a source subject to an approved emissions trading program, 
it was not possible to comply with applicable control measures by 
acquiring sufficient credit from other sources or persons subject to the 
emissions trading program.
    (4) The State shall ensure the public an opportunity, through a 
public hearing process, to comment on the appropriateness of allocating 
compliance supplement pool credits to a source under paragraph 
(e)(3)(iv)(B) of this section.
    (4) If, no later than February 22, 1999, any member of the public 
requests revisions to the source-specific data and vehicle miles 
traveled (VMT) and nonroad mobile growth rates, VMT distribution by 
vehicle class, average speed by roadway type, inspection and maintenance 
program parameters, and other input parameters used to establish the 
State budgets set forth in paragraph (e)(2) of this section or the 2007 
baseline sub-inventory information set forth in paragraph (g)(2)(ii) of 
this section, then EPA will act on that request no later than April 23, 
1999 provided:
    (i) The request is submitted in electronic format;
    (ii) Information is provided to corroborate and justify the need for 
the requested modification;
    (iii) The request includes the following data information regarding 
any electricity-generating source at issue:
    (A) Federal Information Placement System (FIPS) State Code;
    (B) FIPS County Code;
    (C) Plant name;
    (D) Plant ID numbers (ORIS code preferred, State agency tracking 
number also or otherwise);
    (E) Unit ID numbers (a unit is a boiler or other combustion device);
    (F) Unit type;
    (G) Primary fuel on a heat input basis;
    (H) Maximum rated heat input capacity of unit;
    (I) Nameplate capacity of the largest generator the unit serves;
    (J) Ozone season heat inputs for the years 1995 and 1996;
    (K) 1996 (or most recent) average NOX rate for the ozone 
season;
    (L) Latitude and longitude coordinates;
    (M) Stack parameter information ;
    (N) Operating parameter information;
    (O) Identification of specific change to the inventory; and
    (P) Reason for the change;
    (iv) The request includes the following data information regarding 
any non-electricity generating point source at issue:
    (A) FIPS State Code;
    (B) FIPS County Code;
    (C) Plant name;
    (D) Facility primary standard industrial classification code (SIC);

[[Page 149]]

    (E) Plant ID numbers (NEDS, AIRS/AFS, and State agency tracking 
number also or otherwise);
    (F) Unit ID numbers (a unit is a boiler or other combustion device);
    (G) Primary source classification code (SCC);
    (H) Maximum rated heat input capacity of unit;
    (I) 1995 ozone season or typical ozone season daily NOX 
emissions;
    (J) 1995 existing NOX control efficiency;
    (K) Latitude and longitude coordinates;
    (L) Stack parameter information;
    (M) Operating parameter information;
    (N) Identification of specific change to the inventory; and
    (O) Reason for the change;
    (v) The request includes the following data information regarding 
any stationary area source or nonroad mobile source at issue:
    (A) FIPS State Code;
    (B) FIPS County Code;
    (C) Primary source classification code (SCC);
    (D) 1995 ozone season or typical ozone season daily NOX 
emissions;
    (E) 1995 existing NOX control efficiency;
    (F) Identification of specific change to the inventory; and
    (G) Reason for the change;
    (vi) The request includes the following data information regarding 
any highway mobile source at issue:
    (A) FIPS State Code;
    (B) FIPS County Code;
    (C) Primary source classification code (SCC) or vehicle type;
    (D) 1995 ozone season or typical ozone season daily vehicle miles 
traveled (VMT);
    (E) 1995 existing NOX control programs;
    (F) identification of specific change to the inventory; and
    (G) reason for the change.
    (f) Each SIP revision must set forth control measures to meet the 
NOX 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 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 mass NOX emissions; or
    (C) Impose any other regulatory requirement which the State has 
demonstrated to EPA provides equivalent or greater assurance than 
options in paragraphs (f)(2)(i)(A) or (f)(2)(i)(B) of this section that 
the State will comply with its NOX 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

[[Page 150]]

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 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 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 budget, as set forth for the State in paragraph 
(g)(2)(ii) of this section, 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 measures assumed in 
developing the baseline inventory.
    (ii) The base year 2007 NOX emissions sub-inventories for 
each State, expressed in tons per ozone season, are as follows:

----------------------------------------------------------------------------------------------------------------
                     State                          EGU      Non-EGU    Area     Nonroad    Highway      Total
----------------------------------------------------------------------------------------------------------------
Alabama.......................................      76,926    58,791    28,762    20,186      52,202     236,867
Connecticut...................................       5,636     5,124     4,821    10,736      19,902      46,220
Delaware......................................       5,838     2,370     1,129     5,651       8,524      23,512
District of Columbia..........................           3       300       830     3,138       2,215       6,485
Georgia.......................................      86,455    36,827    13,212    26,497      90,499     253,489
Illinois......................................     119,311    72,183     9,369    57,033     117,354     375,250
Indiana.......................................     136,773    80,884    29,070    26,536      82,170     355,433
Kentucky......................................     107,829    29,328    31,807    15,042      54,406     238,412
Maryland......................................      32,603    15,554     4,448    20,121      30,832     103,558
Massachusetts.................................      16,479    11,229    11,048    20,166      28,641      87,563
Michigan......................................      86,600    62,988    31,721    26,940      79,751     288,000
Missouri......................................      82,097    26,870     7,341    20,875      52,554     189,737
New Jersey....................................      18,352    18,345    12,431    23,565      35,890     108,584
New York......................................      39,199    28,281    17,423    42,091     126,664     253,659
North Carolina................................      84,815    34,888    11,067    22,045      75,785     228,600
Ohio..........................................     163,132    53,074    21,860    43,780      96,572     378,418
Pennsylvania..................................     123,102    82,270    17,842    30,635      93,052     346,900
Rhode Island..................................       1,082     2,031       448     2,455       3,879       9,895
South Carolina................................      36,299    37,495     9,415    14,670      55,585     153,465
Tennessee.....................................      70,908    53,198    13,333    52,985      67,538     257,962
Virginia......................................      40,884    54,414    27,738    27,867      73,619     224,521
West Virginia.................................     115,490    32,235     5,459    10,438      21,325     184,947
Wisconsin.....................................      51,962    22,886    11,253    17,975      70,984     175,061
                                               -----------------------------------------------------------------
Total.........................................   1,501,775   821,563   321,826   541,428   1,339,944   4,526,538
----------------------------------------------------------------------------------------------------------------
Note: Totals may not sum due to rounding.

    (iii) Each revision must contain a summary of NOX mass 
emissions 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 of this part 
(regarding data availability).

[[Page 151]]

    (i) Each revision must provide for monitoring the status of 
compliance with any control measures adopted to meet the NOX 
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 of this part 
(regarding testing, inspection, enforcement, and complaints);
    (3) If the revision contains any transportation control measures, 
then the revision must comply with Sec. 51.213 of this part (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 must require such sources to comply with the 
monitoring provisions of part 75, subpart H.
    (5) For purposes of paragraph (i)(4) 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.
    (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 
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.
    (l)(1) A revision may assign legal authority to local agencies in 
accordance with Sec. 51.232 of this part.
    (2) Each revision must comply with Sec. 51.240 of this part 
(regarding general plan requirements).
    (m) Each revision must comply with Sec. 51.280 of this part 
(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

[[Page 152]]

CAA. Any such finding will be deemed a finding under Sec. 52.31(c) of 
this part and sanctions will be imposed in accordance with the order of 
sanctions and the terms for such sanctions established in Sec. 52.31 of 
this part.
    (o) Each revision must provide for State compliance with the 
reporting requirements set forth in Sec. 51.122 of this part.
    (p)(1) Notwithstanding any other provision of this section, if a 
State adopts regulations substantively identical to 40 CFR part 96 (the 
model NOX budget trading program for SIPs), incorporates such 
part by reference into its regulations, or adopts regulations that 
differ substantively from such part only as set forth in paragraph 
(p)(2) of this section, then that portion of the State's SIP revision is 
automatically approved as satisfying the same portion of the State's 
NOX emission reduction obligations as the State projects such 
regulations will satisfy, provided that:
    (i) The State has the legal authority to take such action and to 
implement its responsibilities under such regulations, and
    (ii) The SIP revision accurately reflects the NOX 
emissions reductions to be expected from the State's implementation of 
such regulations.
    (2) If a State adopts an emissions trading program that differs 
substantively from 40 CFR part 96 in only the following respects, then 
such portion of the State's SIP revision is approved as set forth in 
paragraph (p)(1) of this section:
    (i) The State may expand the applicability provisions of the trading 
program to include units (as defined in 40 CFR 96.2) that are smaller 
than the size criteria thresholds set forth in 40 CFR 96.4(a);
    (ii) The State may decline to adopt the exemption provisions set 
forth in 40 CFR 96.4(b);
    (iii) The State may decline to adopt the opt-in provisions set forth 
in subpart I of 40 CFR part 96;
    (iv) The State may decline to adopt the allocation provisions set 
forth in subpart E of 40 CFR part 96 and may instead adopt any 
methodology for allocating NOX allowances to individual 
sources, provided that:
    (A) The State's methodology does not allow the State to allocate 
NOX allowances in excess of the total amount of 
NOX emissions which the State has assigned to its trading 
program; and
    (B) The State's methodology conforms with the timing requirements 
for submission of allocations to the Administrator set forth in 40 CFR 
96.41; and
    (v) The State may decline to adopt the early reduction credit 
provisions set forth in 40 CFR 96.55(c) and may instead adopt any 
methodology for issuing credit from the State's compliance supplement 
pool that complies with paragraph (e)(3) of this section.
    (3) If a State adopts an emissions trading program that differs 
substantively from 40 CFR part 96 other than as set forth in paragraph 
(p)(2) of this section, then such portion of the State's SIP revision is 
not automatically approved as set forth in paragraph (p)(1) of this 
section but will be reviewed by the Administrator for approvability in 
accordance with the other provisions of this section.

[63 FR 57491, Oct. 27, 1998, as amended at 63 FR 71225, Dec. 24, 1998; 
64 FR 26305, May 14, 1999]



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

    (a) For its transport SIP revision under Sec. 51.121 of this part, 
each State must submit to EPA NOX emissions data as described 
in this section.
    (b) 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) Annual reporting. Each revision must provide for annual 
reporting of NOX emissions data 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) of this 
part. This would include 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

[[Page 153]]

in accordance with Sec. 51.121(g) of this part.
    (ii) If sources report NOX emissions data to EPA annually 
pursuant to a trading program approved under Sec. 51.121(p) of this part 
or pursuant to the monitoring and reporting requirements of subpart H of 
40 CFR part 75, then the State need not provide annual reporting to EPA 
for such sources.
    (2) Triennial reporting. Each plan must provide for triennial (i.e., 
every third year) reporting of NOX emissions data from all 
sources within the State.
    (3) Year 2007 reporting. Each plan must provide for reporting of 
year 2007 NOX emissions data from all sources within the 
State.
    (4) The data availability requirements in Sec. 51.116 of this part 
must be followed for all data submitted to meet the requirements of 
paragraphs (b)(1),(2) and (3) of this section.
    (c) The data reported in paragraph (b) of this section for 
stationary point sources must meet the following minimum criteria:
    (1) For annual data reporting purposes the data must include the 
following minimum elements:
    (i) Inventory year.
    (ii) State Federal Information Placement System code.
    (iii) County Federal Information Placement System code.
    (iv) Federal ID code (plant).
    (v) Federal ID code (point).
    (vi) Federal ID code (process).
    (vii) Federal ID code (stack).
    (vii) Site name.
    (viii) Physical address.
    (ix) SCC.
    (x) Pollutant code.
    (xi) Ozone season emissions.
    (xii) Area designation.
    (2) In addition, the annual data must include the following minimum 
elements as applicable to the emissions estimation methodology.
    (i) Fuel heat content (annual).
    (ii) Fuel heat content (seasonal).
    (iii) Source of fuel heat content data.
    (iv) Activity throughput (annual).
    (v) Activity throughput (seasonal).
    (vi) Source of activity/throughput data.
    (vii) Spring throughput (%).
    (viii) Summer throughput (%).
    (ix) Fall throughput (%).
    (x) Work weekday emissions.
    (xi) Emission factor.
    (xii) Source of emission factor.
    (xiii) Hour/day in operation.
    (xiv) Operations Start time (hour).
    (xv) Day/week in operation.
    (xvi) Week/year in operation.
    (3) The triennial and 2007 inventories must include the following 
data elements:
    (i) The data required in paragraphs (c)(1) and (c)(2) of this 
section.
    (ii) X coordinate (latitude).
    (iii) Y coordinate (longitude).
    (iv) Stack height.
    (v) Stack diameter.
    (vi) Exit gas temperature.
    (vii) Exit gas velocity.
    (viii) Exit gas flow rate.
    (ix) SIC.
    (x) Boiler/process throughput design capacity.
    (xi) Maximum design rate.
    (xii) Maximum capacity.
    (xiii) Primary control efficiency.
    (xiv) Secondary control efficiency.
    (xv) Control device type.
    (d) The data reported in paragraph (b) of this section for area 
sources must include the following minimum elements:
    (1) For annual inventories it must include:
    (i) Inventory year.
    (ii) State FIPS code.
    (iii) County FIPS code.
    (iv) SCC.
    (v) Emission factor.
    (vi) Source of emission factor.
    (vii) Activity/throughput level (annual).
    (viii) Activity throughput level (seasonal).
    (ix) Source of activity/throughput data.
    (x) Spring throughput (%).
    (xi) Summer throughput (%).
    (xii) Fall throughput (%).
    (xiii) Control efficiency (%).
    (xiv) Pollutant code.
    (xv) Ozone season emissions.
    (xvi) Source of emissions data.
    (xvii) Hour/day in operation.
    (xviii) Day/week in operation.
    (xix) Week/year in operations.
    (2) The triennial and 2007 inventories must contain, at a minimum, 
all the data required in paragraph (d)(1) of this section.

[[Page 154]]

    (e) The data reported in paragraph (b) of this section for mobile 
sources must meet the following minimum criteria:
    (1) For the annual, triennial, and 2007 inventory purposes, the 
following data must be reported:
    (i) Inventory year.
    (ii) State FIPS code.
    (iii) County FIPS code.
    (iv) SCC.
    (v) Emission factor.
    (vi) Source of emission factor.
    (vii) Activity (this must be reported for both highway and nonroad 
activity. Submit nonroad activity in the form of hours of activity at 
standard load (either full load or average load) for each engine type, 
application, and horsepower range. Submit highway activity in the form 
of vehicle miles traveled (VMT) by vehicle class on each roadway type. 
Report both highway and nonroad activity for a typical ozone season 
weekday day, if the State uses EPA's default weekday/weekend activity 
ratio. If the State uses a different weekday/weekend activity ratio, 
submit separate activity level information for weekday days and weekend 
days).
    (viii) Source of activity data.
    (ix) Pollutant code.
    (x) Summer work weekday emissions.
    (xi) Ozone season emissions.
    (xii) Source of emissions data.
    (2) [Reserved]
    (f) Approval of ozone season calculation by EPA. Each State must 
submit for EPA approval an example of the calculation procedure used to 
calculate ozone season emissions along with sufficient information for 
EPA to verify the calculated value of ozone season emissions.
    (g) Reporting schedules. (1) Annual reports are to begin with data 
for emissions occurring in the year 2003.
    (2) Triennial reports are to begin with data for emissions occurring 
in the year 2002.
    (3) Year 2007 data are to be submitted for emissions occurring in 
the year 2007.
    (4) States must submit data for a required year no later than 12 
months after the end of the calendar year for which the data are 
collected.
    (h) Data reporting procedures. When submitting a formal 
NOX budget emissions report and associated data, States shall 
notify the appropriate EPA Regional Office.
    (1) States are required to report emissions data in an electronic 
format to one of the locations listed in this paragraph (h). Several 
options are available for data reporting.
    (2) An agency may choose to continue reporting to the EPA Aerometric 
Information Retrieval System (AIRS) system using the AIRS facility 
subsystem (AFS) format for point sources. (This option will continue for 
point sources for some period of time after AIRS is reengineered (before 
2002), at which time this choice may be discontinued or modified.)
    (3) An agency may convert its emissions data into the Emission 
Inventory Improvement Program/Electronic Data Interchange (EIIP/EDI) 
format. This file can then be made available to any requestor, either 
using E-mail, floppy disk, or value added network (VAN), or can be 
placed on a file transfer protocol (FTP) site.
    (4) An agency may submit its emissions data in a proprietary format 
based on the EIIP data model.
    (5) For options in paragraphs (h)(3) and (4) of this section, the 
terms submitting and reporting data are defined as either providing the 
data in the EIIP/EDI format or the EIIP based data model proprietary 
format to EPA, Office of Air Quality Planning and Standards, Emission 
Factors and Inventory Group, directly or notifying this group that the 
data are available in the specified format and at a specific electronic 
location (e.g., FTP site).
    (6) For annual reporting (not for triennial reports), a State may 
have sources submit the data directly to EPA to the extent the sources 
are subject to a trading program that qualifies for approval under 
Sec. 51.121(q) of this part, and the State has agreed to accept data in 
this format. The EPA will make both the raw data submitted in this 
format and summary data available to any State that chooses this option.
    (i) Definitions. As used in this section, the following words and 
terms shall have the meanings set forth below:
    (1) Annual emissions. Actual emissions for a plant, point, or 
process, either measured or calculated.

[[Page 155]]

    (2) Ash content. Inert residual portion of a fuel.
    (3) Area designation. The designation of the area in which the 
reporting source is located with regard to the ozone NAAQS. This would 
include attainment or nonattainment designations. For nonattainment 
designations, the classification of the nonattainment area must be 
specified, i.e., transitional, marginal, moderate, serious, severe, or 
extreme.
    (4) Boiler design capacity. A measure of the size of a boiler, based 
on the reported maximum continuous steam flow. Capacity is calculated in 
units of MMBtu/hr.
    (5) Control device type. The name of the type of control device 
(e.g., wet scrubber, flaring, or process change).
    (6) Control efficiency. The emissions reduction efficiency of a 
primary control device, which shows the amount of reductions of a 
particular pollutant from a process' emissions due to controls or 
material change. Control efficiency is usually expressed as a percentage 
or in tenths.
    (7) Day/week in operations. Days per week that the emitting process 
operates.
    (8) Emission factor. Ratio relating emissions of a specific 
pollutant to an activity or material throughput level.
    (9) Exit gas flow rate. Numeric value of stack gas flow rate.
    (10) Exit gas temperature. Numeric value of an exit gas stream 
temperature.
    (11) Exit gas velocity. Numeric value of an exit gas stream 
velocity.
    (12) Fall throughput (%). Portion of throughput for the 3 fall 
months (September, October, November). This represents the expression of 
annual activity information on the basis of four seasons, typically 
spring, summer, fall, and winter. It can be represented either as a 
percentage of the annual activity (e.g., production in summer is 40 
percent of the year's production), or in terms of the units of the 
activity (e.g., out of 600 units produced, spring = 150 units, summer = 
250 units, fall = 150 units, and winter = 50 units).
    (13) Federal ID code (plant). Unique codes for a plant or facility, 
containing one or more pollutant-emitting sources.
    (14) Federal ID code (point). Unique codes for the point of 
generation of emissions, typically a physical piece of equipment.
    (15) Federal ID code (stack number). Unique codes for the point 
where emissions from one or more processes are released into the 
atmosphere.
    (16) Federal Information Placement System (FIPS). The system of 
unique numeric codes developed by the government to identify States, 
counties, towns, and townships for the entire United States, Puerto 
Rico, and Guam.
    (17) Heat content. The thermal heat energy content of a solid, 
liquid, or gaseous fuel. Fuel heat content is typically expressed in 
units of Btu/lb of fuel, Btu/gal of fuel, joules/kg of fuel, etc.
    (18) Hr/day in operations. Hours per day that the emitting process 
operates.
    (19) Maximum design rate. Maximum fuel use rate based on the 
equipment's or process' physical size or operational capabilities.
    (20) Maximum nameplate capacity. A measure of the size of a 
generator which is put on the unit's nameplate by the manufacturer. The 
data element is reported in megawatts (MW) or kilowatts (KW).
    (21) Mobile source. A motor vehicle, nonroad engine or nonroad 
vehicle, where:
    (i) Motor vehicle means any self-propelled vehicle designed for 
transporting persons or property on a street or highway;
    (ii) Nonroad engine means an internal combustion engine (including 
the fuel system) that is not used in a motor vehicle or a vehicle used 
solely for competition, or that is not subject to standards promulgated 
under section 111 or section 202 of the CAA;
    (iii) Nonroad vehicle means a vehicle that is powered by a nonroad 
engine and that is not a motor vehicle or a vehicle used solely for 
competition.
    (22) Ozone season. The period May 1 through September 30 of a year.
    (23) Physical address. Street address of facility.
    (24) Point source. A non-mobile source which emits 100 tons of 
NOX or more per year unless the State designates as a point 
source a non-mobile source emitting at a specified level lower than

[[Page 156]]

100 tons of NOX per year. A non-mobile source which emits 
less NOX per year than the point source threshold is an area 
source.
    (25) Pollutant code. A unique code for each reported pollutant that 
has been assigned in the EIIP Data Model. Character names are used for 
criteria pollutants, while Chemical Abstracts Service (CAS) numbers are 
used for all other pollutants. Some States may be using storage and 
retrieval of aerometric data (SAROAD) codes for pollutants, but these 
should be able to be mapped to the EIIP Data Model pollutant codes.
    (26) Process rate/throughput. A measurable factor or parameter that 
is directly or indirectly related to the emissions of an air pollution 
source. Depending on the type of source category, activity information 
may refer to the amount of fuel combusted, the amount of a raw material 
processed, the amount of a product that is manufactured, the amount of a 
material that is handled or processed, population, employment, number of 
units, or miles traveled. Activity information is typically the value 
that is multiplied against an emission factor to generate an emissions 
estimate.
    (27) SCC. Source category code. A process-level code that describes 
the equipment or operation emitting pollutants.
    (28) Secondary control efficiency (%). The emissions reductions 
efficiency of a secondary control device, which shows the amount of 
reductions of a particular pollutant from a process' emissions due to 
controls or material change. Control efficiency is usually expressed as 
a percentage or in tenths.
    (29) SIC. Standard Industrial Classification code. U.S. Department 
of Commerce's categorization of businesses by their products or 
services.
    (30) Site name. The name of the facility.
    (31) Spring throughput (%). Portion of throughput or activity for 
the 3 spring months (March, April, May). See the definition of Fall 
Throughput.
    (32) Stack diameter. Stack physical diameter.
    (33) Stack height. Stack physical height above the surrounding 
terrain.
    (34) Start date (inventory year). The calendar year that the 
emissions estimates were calculated for and are applicable to.
    (35) Start time (hour). Start time (if available) that was 
applicable and used for calculations of emissions estimates.
    (36) Summer throughput (%). Portion of throughput or activity for 
the 3 summer months (June, July, August). See the definition of Fall 
Throughput.
    (37) Summer work weekday emissions. Average day's emissions for a 
typical day.
    (38) VMT by Roadway Class. This is an expression of vehicle activity 
that is used with emission factors. The emission factors are usually 
expressed in terms of grams per mile of travel. Since VMT does not 
directly correlate to emissions that occur while the vehicle is not 
moving, these non-moving emissions are incorporated into EPA's MOBILE 
model emission factors.
    (39) Week/year in operation. Weeks per year that the emitting 
process operates.
    (40) Work Weekday. Any day of the week except Saturday or Sunday.
    (41) X coordinate (latitude). East-west geographic coordinate of an 
object.
    (42) Y coordinate (longitude). North-south geographic coordinate of 
an object.

[63 FR 57496, Oct. 27, 1998]



        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 g/m3 (0.04 ppm) annual 
arithmetic mean; 455 g/m3 (0.17 ppm) 24-hour 
maximum.
    (2) Particulate matter--95 g/m3 annual geometric 
mean; 325 g/m3 24-hour maximum.

[[Page 157]]

    (3) Carbon monoxide--55 mg/m3 (48 ppm) 1-hour maximum; 14 
mg/m3 (12 ppm) 8-hour maximum.
    (4) Nitrogen dioxide--100 g/m3 (0.06 ppm) annual 
arithmetic mean.
    (5) Ozone--195 g/m3 (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 g/m3 (0.02-0.04 ppm) 
annual arithmetic mean; 260-445 g/m3 (0.10-0.17 ppm) 
24-hour maximum; any concentration above 1,300 g/m3 
(0.50 ppm) three-hour average.
    (2) Particulate matter--60-95 g/m3 annual 
geometric mean; 150-325 g/m3 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 mimimum, 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 g/m3 (1.0 ppm) 24-hour 
average.
PM10--600 micrograms/cubic meter; 24-hour average.
Carbon monoxide--57.5 mg/m3 (50 ppm) 8-hour average; 86.3 mg/
m3 (75 ppm) 4-hour average; 144 mg/m3 (125 ppm) 1-
hour average.
Ozone--1,200 ug/m3 (0.6 ppm) 2-hour average.
Nitrogen dioxide--3.750 ug/m3 (2.0 ppm) 1-hour average; 938 
ug/m3 (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
    (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.

[[Page 158]]



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.
    (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

[[Page 159]]

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;
    (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).



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.



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 provisions satisfying sections 
172(b)(6) 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 any air pollutant subject to 
regulation under the Act.
    (ii) 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

[[Page 160]]

Printing Office stock numbers 4101-0065 and 003-005-00176-0, 
respectively).
    (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 which emits, or has the 
potential to emit 100 tons per year or more of any pollutant subject to 
regulation under the Act, or
    (2) Any physical change that would occur at a stationary source not 
qualifying under paragraph (a)(1)(iv)(A)(1) 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;
    (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 a significant net emissions increase of any pollutant subject to 
regulation under the Act.
    (B) Any net emissions increase that is considered 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;
    (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;

[[Page 161]]

    (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) The addition, replacement or use of a pollution control project 
at an existing electric utility steam generating unit, unless the 
reviewing authority determines that such addition, replacement, or use 
renders the unit less environmentally beneficial, or except:
    (i) When the reviewing authority has reason to believe that the 
pollution control project would result in a significant net increase in 
representative actual annual emissions of any criteria pollutant over 
levels used for that source in the most recent air quality impact 
analysis in the area conducted for the purpose of title I, if any, and
    (ii) The reviewing authority determines that the increase will cause 
or contribute to a violation of any national ambient air quality 
standard or PSD increment, or visibility limitation.
    (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.
    (vi)(A) Net emissions increase means the amount by which the sum of 
the following exceeds zero:
    (1) Any increase in actual emissions from a particular physical 
change or change in the method of operation at a stationary source; and
    (2) Any other increases and decreases in actual emissions at the 
source that are contemporaneous with the particular change and are 
otherwise creditable.
    (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.
    (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 federally enforceable 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 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.
    (F) An increase that results from a physical change at a source 
occurs

[[Page 162]]

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) Emissions unit means any part of a stationary source which 
emits or would have the potential to emit any pollutant subject to 
regulation under the the Act.
    (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) Significant means, in reference to a net emissions increase pr 
the potential of a source to emit any of the following pollutions, as 
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
Lead: 0.6 tpy

    (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 
pollutant from an emissions unit as determined in accordance with 
paragraphs (a)(1)(xii) (B) through (D) of this section.
    (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 two-year 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 the source-specific 
allowable emissions for the unit are equivalent to the actual emissions 
of the unit.
    (D) For any emissions unit (other than an electric utility steam 
generating unit specified in paragraph (a)(1)(xii)(E) of this section) 
which has not begun normal operations on the particular date, actual 
emissions shall equal the potential to emit of the unit on that date.
    (E) For an electric utility steam generating unit (other than a new 
unit or the replacement of an existing unit) actual emissions of the 
unit following the physical or operational change shall equal the 
representative actual annual emissions of the unit, provided the source 
owner or operator maintains and submits to the reviewing authority, on 
an annual basis for a period of 5 years from the date the unit resumes

[[Page 163]]

regular operation, information demonstrating that the physical or 
operational change did not result in an emissions increase. A longer 
period, not to exceed 10 years, may be required by the reviewing 
authority if it determines such a period to be more representative of 
normal source post-change operations.
    (xiii) Lowest achievable emission rate 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 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) which would result in 
a change in actual 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) Representative actual annual emissions means the average rate, 
in tons per year, at which the source is projected to emit a pollutant 
for the two-year period after a physical change or change in the method 
of operation of

[[Page 164]]

a unit, (or a different consecutive two-year period within 10 years 
after that change, where the reviewing authority determines that such 
period is more representative of source operations), considering the 
effect any such change will have on increasing or decreasing the hourly 
emissions rate and on projected capacity utilization. In projecting 
future emissions the reviewing authority shall:
    (A) Consider all relevant information, including but not limited to, 
historical operational data, the company's own representations, filings 
with the State or Federal regulatory authorities, and compliance plans 
under title IV of the Clean Air Act; and
    (B) Exclude, in calculating any increase in emissions that results 
from the particular physical change or change in the method of operation 
at an electric utility steam generating unit, that portion of the unit's 
emissions following the change that could have been accommodated during 
the representative baseline period and is attributable to an increase in 
projected capacity utilization at the unit that is unrelated to the 
particular change, including any increased utilization due to the rate 
of electricity demand growth for the utility system as a whole.
    (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 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) Pollution control project means any activity or project at an 
existing electric utility steam generating unit for purposes of reducing 
emissions from such unit. Such activities or projects are limited to:
    (A) The installation of conventional or innovative pollution control 
technology, including but not limited to advanced flue gas 
desulfurization, sorbent injection for sulfur dioxide and nitrogen 
oxides controls and electrostatic precipitators;
    (B) An activity or project to accommodate switching to a fuel which 
is less polluting than the fuel used prior to the activity or project, 
including, but not limited to natural gas or coal reburning, or the 
cofiring of natural gas and other fuels for the purpose of controlling 
emissions;
    (C) A permanent clean coal technology demonstration project 
conducted under title II, sec. 101(d) of the Further Continuing 
Appropriations Act of 1985 (sec. 5903(d) of title 42 of the United 
States Code), or subsequent appropriations, 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; or
    (D) A permanent clean coal technology demonstration project that 
constitutes a repowering project.
    (2) Each plan shall adopt a preconstruction review program to 
satisfy the requirements of sections 172(b)(6) and 173 of the Act for 
any area designated nonattainment for any national ambient air quality 
standard under 40 CFR 81.300 et seq. Such a program shall apply to any 
new major stationary source or major modification that is major for the 
pollutant for

[[Page 165]]

which the area is designated nonattainment, if the stationary source or 
modification would locate anywhere in the designated nonattainment area.
    (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 
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 
source or curtailing production or operating hours below baseline levels 
may be generally credited if such reductions are permanent, 
quantifiable, and federally enforceable, and if the area has an EPA-
approved attainment plan. In addition, the shutdown or curtailment is 
creditable only if it occurred on or after the date specified for this 
purpose in the plan, and if such date is on or after the date of the 
most recent emissions inventory used in the plan's demonstration of 
attainment. Where the plan does not specify a cutoff date for shutdown 
credits, the date of the most recent emissions inventory or attainment 
demonstration, as the case may be, shall apply. However, in no event may 
credit be given for shutdowns which occurred prior to August 7, 1977. 
For purposes of this paragraph, a permitting authority may choose to 
consider a prior shutdown or curtailment to have occurred after the date 
of its most recent emissions inventory, if the inventory explicitly 
includes as current existing emissions the emissions from such 
previously shutdown or curtailed sources.
    (2) Such reductions may be credited in the absence of an approved 
attainment demonstration only if the shutdown or curtailment occurred on 
or after the date the new source permit application is filed, or, if the 
applicant can establish that the proposed new source is a replacement 
for the shutdown or curtailed source, and the cutoff date provisions of 
Sec. 51.165(a)(3)(ii)(C)(1) are observed.
    (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.

[[Page 166]]

    (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.
    (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 emission 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;
    (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;
    (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;
    (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 167]]



--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                Averaging time (hours)
             Pollutant                       Annual         --------------------------------------------------------------------------------------------
                                                                       24                      8                      3                      1
--------------------------------------------------------------------------------------------------------------------------------------------------------
SO2................................  1.0 g/m\3\...  5 g/m\3\.....    ...................  25 g/m\3\...
PM10...............................  1.0 g/m\3\...  5 g/m\3\.....    ...................    ...................
NO2................................  1.0 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.

[51 FR 40669, Nov. 7, 1986, as amended at 52 FR 24713, July 1, 1987; 52 
FR 29386, Aug 7, 1987; 54 FR 27285, 27299 June 28, 1989; 57 FR 3946, 
Feb. 3, 1992; 57 FR 32334, July 21, 1992]



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 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 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, including any amendment 
adopted simultaneously with this paragraph, shall adopt and submit such 
plan revision to the Administrator for approval within 9 months after 
the effective date of the new amendments.
    (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

[[Page 168]]

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.
    (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 
pollutant subject to regulation under the Act: 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, 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, 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 any 
air pollutant subject to regulation under the Act; 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 
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:
    (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;
    (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

[[Page 169]]

method of operation of a major stationary source that would result in a 
significant net emissions increase of any pollutant subject to 
regulation under the Act.
    (ii) Any net emissions increase 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 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;
    (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) The addition, replacement or use of a pollution control project 
at an existing electric utility steam generating unit, unless the 
Administrator determines that such addition, replacement, or use renders 
the unit less environmentally beneficial, or except:
    (1) When the reviewing authority has reason to believe that the 
pollution control project would result in a significant net increase in 
representative actual annual emissions of any criteria pollutant over 
levels used for that source in the most recent air quality impact 
analysis in the area conducted for the purpose of title I, if any, and
    (2) The reviewing authority determines that the increase will cause 
or contribute to a violation of any national ambient air quality 
standard or PSD increment, or visibility limitation.
    (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.
    (3)(i) Net emissions increase means the amount by which the sum of 
the following exceeds zero:
    (a) Any increase in actual emissions from a particular physical 
change or change in the method of operation at a stationary source; and
    (b) Any other increases and decreases in actual emissions at the 
source that are contemporaneous with the particular change and are 
otherwise creditable.
    (ii) An increase or decrease in actual emissions is contemporaneous 
with the increase from the particular change only if it occurs within a 
reasonable

[[Page 170]]

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 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.
    (iv) An increase or decrease in actual emissions of sulfur dioxide, 
particulate matter, or nitrogen oxides, which 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. With respect to particulate matter, only 
PM-10 emissions can be used to evaluate the net emissions increase for 
PM-10.
    (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 federally enforceable at and after the time that actual 
construction on the particular change begins; and
    (c) It has approximately the same qualitative significance for 
public health and welfare as that attributed to the increase from the 
particular change.
    (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.
    (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 any air pollutant subject to 
regulation under the Act.
    (6) 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).
    (7) Emissions unit means any part of a stationary source which emits 
or would have the potential to emit any pollutant subject to regulation 
under the Act.
    (8) Construction means any physical change or change in the method 
of operation (including fabrication, erection, installation, demolition, 
or modification of an emissions unit) which would result in a change in 
actual 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.

[[Page 171]]

    (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 pollutant subject to regulation under the Act 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 which 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 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 which 
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 from any major stationary source on which 
construction commenced after the major source baseline date; and
    (b) Actual emissions increases and decreases at any stationary 
source occurring after the minor source baseline date.
    (14)(i) Major source baseline date means:
    (a) In the case of particulate matter and sulfur dioxide, January 6, 
1975, and
    (b) In the case of nitrogen dioxide, February 8, 1988.
    (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 particulate matter and sulfur dioxide, August 7, 
1977, and
    (b) In the case of nitrogen dioxide, February 8, 1988.
    (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

[[Page 172]]

is designated as attainment or unclassifiable under section 107(d)(i) 
(D) or (E) 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) (D) or (E) 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 equal to or greater than 1 
g/m\3\ (annual average) of the pollutant for which the minor 
source baseline date is established.
    (ii) Area redesignations under section 107(d)(1) (D) or (E) 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.
    (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.

[[Page 173]]

    (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 
pollutant from an emissions unit, as determined in accordance with 
paragraphs (b)(21) (ii) through (iv) of this section.
    (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 two-year period which precedes the 
particular date and which is representative of normal source operation. 
The reviewing authority may 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 (other than an electric utility steam 
generating unit specified in paragraph (b)(21)(v) of this section) which 
has not begun normal operations on the particular date, actual emissions 
shall equal the potential to emit of the unit on that date.
    (v) For an electric utility steam generating unit (other than a new 
unit or the replacement of an existing unit) actual emissions of the 
unit following the physical or operational change shall equal the 
representative actual annual emissions of the unit following the 
physical or operational change, provided the source owner or operator 
maintains and submits to the reviewing authority, on an annual basis for 
a period of 5 years from the date the unit resumes regular operation, 
information demonstrating that the physical or operational change did 
not result in an emissions increase. A longer period, not to exceed 10 
years, may be required by the reviewing authority if it determines such 
a period to be more representative of normal source post-change 
operations.
    (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.
Ozone: 40 tpy of volatile organic compounds
Lead: 0.6 tpy
Asbestos: 0.007 tpy
Beryllium: 0.0004 tpy
Mercury: 0.1 tpy
Vinyl chloride: 1 tpy
Fluorides: 3 tpy
Sulfuric acid mist: 7 tpy
Hydrogen sulfide (H2 S): 10 tpy
Total reduced sulfur (including H2 S): 10 tpy
Reduced sulfur compounds (including H2 S): 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 articulate 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)


[[Page 174]]


    (ii) Significant means, in reference to a net emissions increase or 
the potential of a source to emit a pollutant subject to regulation 
under the Act 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 g/m3 
(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) Pollution control project means any activity or project 
undertaken at an existing electric utility steam generating unit for 
purposes of reducing emissions from such unit. Such activities or 
projects are limited to:
    (i) The installation of conventional or innovative pollution control 
technology, including but not limited to advanced flue gas 
desulfurization, sorbent injection for sulfur dioxide and nitrogen 
oxides controls and electrostatic precipitators;
    (ii) An activity or project to accommodate switching to a fuel which 
is less polluting than the fuel used prior to the activity or project, 
including but not limited to natural gas or coal re-burning, or the co-
firing of natural gas and other fuels for the purpose of controlling 
emissions;
    (iii) A permanent clean coal technology demonstration project 
conducted under title II, section 101(d) of the Further Continuing 
Appropriations Act of 1985 (section 5903(d) of title 42 of the United 
States Code), or subsequent appropriations, 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, or
    (iv) A permanent clean coal technology demonstration project that 
constitutes a repowering project.
    (32) Representative actual annual emissions means the average rate, 
in tons per year, at which the source is projected to emit a pollutant 
for the two-year period after a physical change or change in the method 
of operation of a unit, (or a different consecutive two-year period 
within 10 years after that change, where the reviewing authority 
determines that such period is more representative of normal source 
operations), considering the effect any such change will have on 
increasing or decreasing the hourly emissions rate and on projected 
capacity utilization. In projecting future emissions the reviewing 
authority shall:
    (i) Consider all relevant information, including but not limited to, 
historical operational data, the company's own representations, filings 
with the State or Federal regulatory authorities, and compliance plans 
under title IV of the Clean Air Act; and
    (ii) Exclude, in calculating any increase in emissions that results 
from the particular physical change or change in the method of operation 
at an electric utility steam generating

[[Page 175]]

unit, that portion of the unit's emissions following the change that 
could have been accommodated during the representative baseline period 
and is attributable to an increase in projected capacity utilization at 
the unit that is unrelated to the particular change, including any 
increased utilization due to the rate of electricity demand growth for 
the utility system as a whole.
    (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 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.
    (c) Ambient air increments. 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 
concentration over the baseline concentration shall be limited to the 
following:

[[Page 176]]



------------------------------------------------------------------------
                                                               Maximum
                                                              allowable
                                                               increase
                         Pollutant                           (micrograms
                                                              per cubic
                                                                meter)
------------------------------------------------------------------------
                                 Class I
------------------------------------------------------------------------
 
Particulate matter:
    PM-10, annual arithmetic mean..........................          4
    PM-10, 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
------------------------------------------------------------------------
 
Particulate matter:
    PM-10, annual arithmetic mean..........................         17
    PM-10, 24-hr maximum...................................         30
Sulfur dioxide:
    Annual arithmetic mean.................................         20
    24-hr maximum..........................................         91
    3-hr maximum...........................................        512
Nitrogen dioxide:
    Annual arithmetic mean.................................         25
 
------------------------------------------------------------------------
                                Class III
 
------------------------------------------------------------------------
Particulate matter:
    PM-10, annual arithmetic mean..........................         34
    PM-10, 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.
    (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 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

[[Page 177]]

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, 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

[[Page 178]]

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 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) Review of major stationary sources and major modifications--
source applicability and exemptions.
    (1) The plan shall provide that no major stationary source or major 
modification shall begin actual construction unless, as a minumum, 
requirements equivalent to those contained in paragraphs (j) through (r) 
of this section have been met.
    (2) The plan shall provide that the requirements equivalent to those 
contained in paragraphs (j) through (r) of this section shall apply to 
any major stationary source and any major modification with respect to 
each pollutant subject to regulation under the Act

[[Page 179]]

that it would emit, except as this section would otherwise allow.
    (3) The plan shall provide that requirements equivalent to those 
contained in paragraphs (j) through (r) of this section apply only to 
any major stationary source or major modification that would be 
constructed in an area which is designated as attainment or 
unclassifiable under section 107(a)(1) (D) or (E) of the Act; and
    (4) 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 
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;
    (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.
    (5) 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.
    (6) 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

[[Page 180]]

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.
    (7) 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 pollutant 
subject to regulation under the Act from the modification after the 
application of best available control technology would be less than 50 
tons per year.
    (8) 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/m3, 8-hour average;
    (b) Nitrogen dioxide--14 ug/m3, annual average;
    (c) Particulate matter--10 g/m\3\ of PM-10, 24-hour 
average.
    (d) Sulfur dioxide--13 ug/m3, 24-hour average;
    (e) Ozone; 1
---------------------------------------------------------------------------

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

    (f) Lead--0.1 g/m\3\, 3-month average.
    (g) Mercury--0.25 ug/m3, 24-hour average;
    (h) Beryllium--0.001 g/m\3\, 24-hour average:
    (i) Fluorides--0.25 ug/m3, 24-hour average;
    (j) Vinyl chloride--15 ug/m3, 24-hour average;
    (k) Total reduced sulfur--10 ug/m3, 1-hour average;
    (l) Hydrogen sulfide--0.2 g/m\3\, 1-hour average:
    (m) Reduced sulfur compounds--10 ug/m3, 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 
(i)(8)(i) of this section; or
    (iii) The pollutants is not listed in paragraph (i)(8)(i) of this 
section.
    (9) 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.
    (10) 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.
    (11) The plan may provide that the permitting requirements 
equivalent to those contained in paragraph (k)(2) 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

[[Page 181]]

permitting authority subsequently determined that the application as 
submitted before that date was complete.
    (12) The plan may provide that the permitting requirements 
equivalent to those contained in paragraph (k)(2) 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)(2) 
shall apply with respect to the maximum allowable increases for TSP as 
in effect on the date the application was submitted.
    (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 pollutant subject to regulation under the Act that 
it would have the potential to emit in significant amounts.
    (3) A major modification shall apply best available control 
technology for each pollutant subject to regulation under the Act 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 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. 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:
    (1) Any national ambient air quality standard in any air quality 
control region; or
    (2) Any applicable maximum allowable increase over the baseline 
concentration in any area.
    (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:

[[Page 182]]

    (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 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,

[[Page 183]]

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 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, particulate matter, 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)
------------------------------------------------------------------------
Particulate matter:
    PM-10, annual arithmetic mean..........................         17
    PM-10, 24-hour 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

[[Page 184]]

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 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.
    (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 written public comment.
    (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

[[Page 185]]

Indian Governing body whose lands 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(s) in making a final decision on the approvability of the 
application. The reviewing authority shall make all comments available 
for public inspection in the same locations 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 where the reviewing authority made available preconstruction 
information and public comments relating to the source.
    (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.
    (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;
    (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

[[Page 186]]

    (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.

(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 in the Finding Aids 
section of this volume.



               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 Survelliance

    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:
    (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]

[[Page 187]]



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.
    (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.

[[Page 188]]

    (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]



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.

[[Page 189]]

    (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 
preceeding 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
    (2) Ways in which the public can participate in regulatory and other 
efforts to improve air quality.

[44 FR 27569, May 10, 1979]



                   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

[[Page 190]]

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. (1) General Applicability. The provisions of this 
subpart pertaining to implementation plan requirements for assuring 
reasonable progress in preventing any future and remedying any existing 
visibility impairment are applicable to:
    (i) Each State which has a mandatory Class I Federal area identified 
in part 81, subpart D, of this title, and (ii) each State in which there 
is any source the emissions from which may reasonably be anticipated to 
cause or contribute to any impairment of visibility in any such area.
    (2) The provisions of this subpart pertaining to implementation 
plans to address reasonably attributable visibility impairment are 
applicable to the following States:

  Alabama, Alaska, Arizona, Arkansas, California, Colorado, Florida, 
    Georgia, Hawaii, Idaho, Kentucky, Louisiana, Maine, Michigan, 
    Minnesota, Missouri, Montana, Nevada, New Hampshire, New Jersey, New 
    Mexico, North Carolina, North Dakota, Oklahoma, Oregon, South 
    Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, 
    Virgin Islands, Washington, West Virginia, Wyoming.

    (3) The provisions of this subpart pertaining to implementation 
plans to address regional haze visibility impairment 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]

    Effective Date Note:  At 64 FR 35763, July 1, 1999, Sec. 51.300 was 
amended by revising paragraphs (a), (b)(1) introductory text, and 
(b)(2), and by adding paragraph (b)(3), effective Aug. 30, 1999. For the 
convenience of the user, the superseded text follows:

Sec. 51.300  Purpose and applicability.

    (a) Purpose. The primary purposes of this subpart are (1) to require 
States to develop programs to assure reasonable progress toward meeting 
the national goal of preventing any future, and remedying and existing, 
impairment of visibility in mandatory Class I Federal areas which 
impairment results from man-made air pollution, and (2) 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. 51.24.
    (b) Applicability. (1) The provisions of this subpart are applicable 
to:

                                * * * * *

    (2) The provisions of this subpart are applicable to the following 
States:
    (i) Alabama
    (ii) Alaska
    (iii) Arizona
    (iv) Arkansas
    (v) California
    (vi) Colorado
    (vii) Florida
    (viii) Georgia
    (ix) Hawaii
    (x) Idaho
    (xi) Kentucky
    (xii) Louisiana
    (xiii) Maine
    (xiv) Michigan
    (xv) Minnesota
    (xvi) Missouri
    (xvii) Montana
    (xviii) Nevada
    (xix) New Hampshire
    (xx) New Jersey
    (xxi) New Mexico
    (xxii) North Carolina
    (xxiii) North Dakota
    (xxiv) Oklahoma
    (xxv) Oregon
    (xxvi) South Carolina
    (xxvii) South Dakota
    (xxviii) Tennessee
    (xxix) Texas
    (xxx) Utah
    (xxxi) Vermont
    (xxxii) Virginia

[[Page 191]]

    (xxxiii) Virgin Islands
    (xxxiv) Washington
    (xxxv) West Virginia
    (xxxvi) Wyoming



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.
    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 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).
    Deciview means a measurement of visibility impairment. A deciview is 
a haze index derived from calculated light extinction, such that uniform 
changes in haziness correspond to uniform incremental changes in 
perception across the entire range of conditions, from pristine to 
highly impaired. The deciview haze index is calculated based on the 
following equation (for the purposes of calculating deciview, the 
atmospheric light extinction coefficient must be calculated from aerosol 
measurements):

Deciview haze index=10 lne (bext/10 
Mm-1).
Where bext=the atmospheric light extinction coefficient, 
expressed in inverse megameters (Mm-1).

    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,

[[Page 192]]

    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 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 average visibility impairment 
(measured in deciviews) for the twenty percent of monitored days in a 
calendar year with the lowest amount 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 means any area identified in part 81, 
subpart D of this title.
    Most impaired days means the average visibility impairment (measured 
in deciviews) for the twenty percent of monitored days in a calendar 
year with the highest amount of visibility impairment.
    Natural conditions includes naturally occurring phenomena that 
reduce visibility as measured in terms of light extinction, visual 
range, contrast, or coloration.

[[Page 193]]

    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.
    Reasonably attributable means attributable by visual observation or 
any other technique the State deems appropriate.
    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 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 impairment means any humanly perceptible change in 
visibility (light extinction, visual range, contrast, coloration) from 
that which would have existed under natural conditions.
    Visibility in any mandatory Class I Federal area includes any 
integral vista associated with that area.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35763, 35774, July 1, 
1999]

    Effective Date Note:  At 64 FR 35763, 35774, July 1, 1999, 
Sec. 51.301 was amended by removing the paragraph designations, placing 
the defined terms in alphabetical order, revising the definitions of 
Federal Land Manager, Major Stationary Source, Natural conditions, and 
Visibility impairment, and adding in alphabetical order definitions of 
Reasonably attributable visibility impairment, Regional haze, Deciview, 
State, Most impaired days, Least impaired days, Implementation plan, 
Indian tribe or tribe, BART-eligible source, Geographic enhancement for 
the purpose of Sec. 51.308, and removing ``Section 303'' and adding in 
its place ``Sec. 51.303'' in the definition of ``Significant 
impairment'', effective Aug. 30, 1999. For the convenience of the user, 
the superseded text follows:

Sec. 51.301  Definitions.

                                * * * * *

    (g) Federal Land Manager means the Secretary of the department with 
authority over the Federal Class I area or, with respect to Roosevelt-
Campobello International Park, the Chairman of the Roosevelt-Campobello 
International Park Commission.

                                * * * * *

    (p) Major Stationary Source and major modification mean major 
stationary source and major modification, respectively, as defined in 
Sec. 51.24.

[[Page 194]]

    (q) Natural conditions includes naturally occurring phenomena that 
reduce visibility as measured in terms of visual range, contrast, or 
coloration.

                                * * * * *

    (x) Visibility impairment means any humanly perceptible change in 
visibility (visual range, contrast, coloration) from that which would 
have existed under natural conditions.

                                * * * * *



Sec. 51.302  Implementation control strategies for reasonably attributable visibility impairment.

    (a) Plan Revision Procedures. (1) Each State identified in 
Sec. 51.300(b)(2) must have submitted, not later than September 2, 1981, 
an implementation plan meeting the requirements of this subpart 
pertaining to reasonably attributable visibility impairment.
    (2)(i) The State, prior to adoption of any implementation plan to 
address reasonably attributable visibility impairment required by this 
subpart, must conduct one or more public hearings on such plan in 
accordance with Sec. 51.102.
    (ii) In addition to the requirements in Sec. 51.102, the State must 
provide written notification of such hearings to each affected Federal 
Land Manager, and other affected States, and must state where the public 
can inspect a summary prepared by the Federal Land Managers of their 
conclusions and recommendations, if any, on the proposed plan revision.
    (3) Submission of plans as required by this subpart must be 
conducted in accordance with the procedures in Sec. 51.103.
    (b) State and Federal Land Manager Coordination. (1) The State must 
identify to the Federal Land Managers, in writing and within 30 days of 
the date of promulgation of these regulations, the title of the official 
to which the Federal Land Manager of any mandatory Class I Federal area 
can submit a recommendation on the implementation of this subpart 
including, but not limited to:
    (i) A list of integral vistas that are to be listed by the State for 
the purpose of implementing section 304,
    (ii) Identification of impairment of visibility in any mandatory 
Class I Federal area(s), and
    (iii) Identification of elements for inclusion in the visibility 
monitoring strategy required by section 305.
    (2) The State must provide opportunity for consultation, in person 
and at least 60 days prior to holding any public hearing on the plan, 
with the Federal Land Manager on the proposed SIP revision required by 
this subpart. 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 of the long-term strategy.
    (3) The plan 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.
    (c) General plan requirements for reasonably attributable visibility 
impairment. (1) The affected Federal Land Manager may certify to the 
State, at any time, that there exists reasonably attributable impairment 
of visibility in any mandatory Class I Federal area.
    (2) The plan must contain the following to address reasonably 
attributable impairment:
    (i) A long-term (10-15 years) strategy, as specified in Sec.  51.305 
and Sec. 51.306, including such emission limitations, schedules of 
compliance, and such other measures including schedules for the 
implementation of the elements of the long-term strategy as may be 
necessary to make reasonable progress toward the national goal specified 
in Sec. 51.300(a).
    (ii) An assessment of visibility impairment and a discussion of how 
each element of the plan relates to the preventing of future or 
remedying of existing impairment of visibility in any mandatory Class I 
Federal area within the State.
    (iii) Emission limitations representing BART and schedules for 
compliance with BART for each existing stationary facility identified 
according to paragraph (c)(4) of this section.

[[Page 195]]

    (3) The plan must require each source to maintain control equipment 
required by this subpart and establish procedures to ensure such control 
equipment is properly operated and maintained.
    (4) For any existing reasonably attributable visibility impairment 
the Federal Land Manager certifies to the State under paragraph (c)(1) 
of this section, at least 6 months prior to plan submission or revision:
    (i) The State must identify and analyze for BART each existing 
stationary facility which may reasonably be anticipated to cause or 
contribute to impairment of visibility in any mandatory Class I Federal 
area where the impairment in the mandatory Class I Federal area is 
reasonably attributable to that existing stationary facility. The State 
need not consider any integral vista the Federal Land Manager did not 
identify pursuant to Sec.  51.304(b) at least 6 months before plan 
submission.
    (ii) If the State determines that technologicial or economic 
limitations on the applicability of measurement methodology to a 
particular existing stationary facility 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.
    (iii) BART must be determined for fossil-fuel fired generating 
plants having a total generating capacity in excess of 750 megawatts 
pursuant to ``Guidelines for Determining Best Available Retrofit 
Technology for Coal-fired Power Plants and Other Existing Stationary 
Facilities'' (1980), which is incorporated by reference, exclusive of 
appendix E, which was published in the Federal Register on February 6, 
1980 (45 FR 8210). It is EPA publication No. 450/3-80-009b and is for 
sale from the U.S. Department of Commerce, National Technical 
Information Service, 5285 Port Royal Road, Springfield, Virginia 22161. 
It is also available for inspection at the Office of the Federal 
Register Information Center, 800 North Capitol NW., suite 700, 
Washington, DC.
    (iv) The plan must require that each existing stationary facility 
required to install and operate BART do so as expeditiously as 
practicable but in no case later than five years after plan approval.
    (v) The plan must provide for a BART analysis of any existing 
stationary facility that might cause or contribute to impairment of 
visibility in any mandatory Class I Federal area identified under this 
paragraph (c)(4) at such times, as determined by the Administrator, as 
new technology for control of the pollutant becomes reasonably available 
if:
    (A) The pollutant is emitted by that existing stationary facility,
    (B) Controls representing BART for the pollutant have not previously 
been required under this subpart, and
    (C) The impairment of visibility in any mandatory Class I Federal 
area is reasonably attributable to the emissions of that pollutant.

[45 FR 80089, Dec. 2, 1980, as amended at 57 FR 40042, Sept. 1, 1992; 64 
FR 35764, 35774, July 1, 1999]

    Effective Date Note:  At 64 FR 35764, 35774, July 1, 1999, 
Sec. 51.302 was amended in paragraph (c)(2)(i) by removing ``Section 
305'' and adding ``Sec. 51.305'', by removing ``Section 306'' and adding 
``Sec. 51.306'', by removing ``Section 300(a)'' and adding 
``Sec. 51.300(a)'' and in paragraph (c)(4)(i) by removing ``Section 
304(b)'' and adding ``Sec. 51.304(b)'', and by revising the section 
heading, paragraphs (a), (c) introductory text, (c)(1), (c)(2) 
introductory text, (c)(4) introductory text, and (c)(4)(iv), effective 
Aug. 30, 1999. For the convenience of the user, the superseded text is 
set forth as follows:

Sec. 51.302  Implementation control strategies.

    (a) Plan Revision Procedures. (1) Each State identified in section 
300(b)(2) must submit, no later than nine months from the date of 
promulgation of this regulation, an implementation plan revision meeting 
the requirements of this subpart.
    (2)(i) The State, prior to adoption of any implementation plan 
required by this subpart, must conduct one or more public hearings on 
such plan in accordance with Sec. 51.4.
    (ii) In addition to the requirements in Sec. 51.4, the State must 
provide written notification of such hearings to each affected Federal 
Land Manager, and other affected

[[Page 196]]

States, and must state where the public can inspect a summary prepared 
by the Federal Land Managers of their conclusions and recommendations, 
if any, on the proposed plan.
    (3) Submission of plans as required by this subpart must be 
conducted in accordance with the procedures in Sec. 51.5.

                                * * * * *

    (c) General Plan Requirements. (1) The affected Federal Land Manager 
may certify to the State, at any time, that there exists impairment of 
visibility in any mandatory Class I Federal area.
    (2) The plan must contain:

                                * * * * *

    (4) For any existing visibility impairment the Federal Land Manager 
certifies to the State under paragraph (c)(1) of this section, at least 
6 months prior to plan submission:

                                * * * * *

    (iv) The plan must require that each existing stationary facility 
required to install and operate BART do so as expeditiously as 
practicable but in no case later than five years after plan approval.

                                * * * * *



Sec. 51.303  Exemptions from control.

    (a)(1) Any existing stationary facility subject to the requirement 
under Sec. 51.302 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.
    (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 by 64 FR 35774, July 1, 1999]

    Effective Date Note: At 64 FR 35774, July 1, 1999, Sec. 51.303 was 
amended in paragraph (a)(1) by removing ``Section 302'' and adding 
``Sec. 51.302'' and in paragraphs (c), (d), (g) and (h) by removing 
``Section 303'' and adding ``Sec. 51.303'', effective Aug. 30, 1999.



Sec. 51.304  Identification of integral vistas.

    (a) On or before December 31, 1985 the Federal Land Manager may 
identify any integral vista. The integral vista

[[Page 197]]

must be identified according to criteria the Federal Land Manager 
develops. These criteria must include, but are not limited to, whether 
the integral vista is important to the visitor's visual experience of 
the mandatory Class I Federal area. Adoption of criteria must be 
preceded by reasonable notice and opportunity for public comment on the 
proposed criteria.
    (b) The Federal Land Manager must notify the State of any integral 
vistas identified under paragraph (a) of this section, and the reasons 
therefor.
    (c) The State must list in its implementation plan any integral 
vista the Federal Land Manager identifies at least six months prior to 
plan submission, and must list in its implementation plan at its 
earliest opportunity, and in no case later than at the time of the 
periodic review of the SIP required by Sec. 51.306(c), any integral 
vista the Federal Land Manager identifies after that time.
    (d) The State need not in its implementation plan list any integral 
vista the indentification of which was not made in accordance with the 
criteria in paragraph (a) of this section. In making this finding, the 
State must carefully consider the expertise of the Federal Land Manager 
in making the judgments called for by the criteria for identification. 
Where the State and the Federal Land Manager disagree on the 
identification of any integral vista, the State must give the Federal 
Land Manager an opportunity to consult with the Governor of the State.

[45 FR 80089, Dec. 2, 1980, as amended by 64 FR 35774, July 1, 1999]

    Effective Date Note: At 64 FR 35774, July 1, 1999, Sec. 51.304 was 
amended in paragraph (c) by removing ``Section 306(c)'' and adding 
``Sec. 51.306(c)'', effective Aug. 30, 1999.



Sec. 51.305  Monitoring for reasonably attributable visibility impairment.

    (a) For the purposes of addressing reasonably attributable 
visibility impairment, each State containing a mandatory Class I Federal 
area must include in the plan a strategy for evaluating reasonably 
attributable visibility impairment in any 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.
    (b) The plan must provide for the consideration of available 
visibility data and must provide a mechanism for its use in decisions 
required by this subpart.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35764, July 1, 1999]

    Effective Date Note: At 64 FR 35764, July 1, 1999, Sec. 31.305 was 
amended by revising the section heading and paragraph (a), effective 
Aug. 30, 1999. For the convenience of the user, the superseded text 
follows:

Sec. 51.305  Monitoring.

    (a) The State must include in the plan a strategy for evaluating 
visibility in any 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.

                                * * * * *



Sec. 51.306  Long-term strategy requirements for reasonably attributable visibility impairment.

    (a)(1) For the purposes of addressing reasonably attributable 
visibility impairment, each plan must include a long-term (10-15 years) 
strategy for making reasonable progress toward the national goal 
specified in Sec. 51.300(a). This strategy must cover any existing 
impairment the Federal Land Manager certifies to the State at least 6 
months prior to plan submission, and any integral vista of which the 
Federal Land Manager notifies the State at least 6 months prior to plan 
submission.
    (2) A long-term strategy must be developed for each mandatory Class 
I Federal area located within the State and each mandatory Class I 
Federal area located outside the State which may be affected by sources 
within the State. This does not preclude the development of a single 
comprehensive plan for all such areas.
    (3) The plan must set forth with reasonable specificity why the 
long-term strategy is adequate for making reasonable progress toward the 
national

[[Page 198]]

visibility goal, including remedying existing and preventing future 
impairment.
    (b) The State must coordinate its long-term strategy for an area 
with existing plans and goals, including those provided by the affected 
Federal Land Managers, that may affect impairment of visibility in any 
mandatory Class I Federal area.
    (c) The plan must provide for periodic review and revision, as 
appropriate, of the long-term strategy for addressing reasonably 
attributable visibility impairment. The plan must provide for such 
periodic review and revision not less frequently than every 3 years 
until the date of submission of the State's first plan addressing 
regional haze visibility impairment in accordance with Sec. 51.308(b) 
and (c). On or before this date, the State must revise its plan to 
provide for review and revision of a coordinated long-term strategy for 
addressing reasonably attributable and regional haze visibility 
impairment, and the State must submit the first such coordinated long-
term strategy. Future coordinated long-term strategies must be submitted 
consistent with the schedule for periodic progress reports set forth in 
Sec. 51.308(g). Until the State revises its plan to meet this 
requirement, the State must continue to comply with existing 
requirements for plan review and revision, and with all emission 
management requirements in the plan to address reasonably attributable 
impairment. This requirement does not affect any preexisting deadlines 
for State submittal of a long-term strategy review (or element thereof) 
between August 30, 1999, and the date required for submission of the 
State's first regional haze plan. In addition, the plan must provide for 
review of the long-term strategy as it applies to reasonably 
attributable impairment, and revision as appropriate, within 3 years of 
State receipt of any certification of reasonably attributable impairment 
from a Federal Land Manager. The review process must include 
consultation with the appropriate Federal Land Managers, and the State 
must provide a report to the public and the Administrator on progress 
toward the national goal. This report must include an assessment of:
    (1) The progress achieved in remedying existing impairment of 
visibility in any mandatory Class I Federal area;
    (2) The ability of the long-term strategy to prevent future 
impairment of visibility in any mandatory Class I Federal area;
    (3) Any change in visibility since the last such report, or, in the 
case of the first report, since plan approval;
    (4) Additional measures, including the need for SIP revisions, that 
may be necessary to assure reasonable progress toward the national 
visibility goal;
    (5) The progress achieved in implementing BART and meeting other 
schedules set forth in the long-term strategy;
    (6) The impact of any exemption granted under Sec. 51.303;
    (7) The need for BART to remedy existing visibility impairment of 
any integral vista listed in the plan since the last such report, or, in 
the case of the first report, since plan approval.
    (d) The long-term strategy must provide for review of the impacts 
from any new major stationary source or major modifications on 
visibility in any mandatory Class I Federal area. This review of major 
stationary sources or major modifications must be in accordance with 
Sec. 51.307, Sec. 51.166, Sec. 51.160, and any other binding guidance 
provided by the Agency insofar as these provisions pertain to protection 
of visibility in any mandatory Class I Federal areas.
    (e) The State must consider, at a minimum, the following factors 
during the development of its long-term strategy:
    (1) Emission reductions due to ongoing air pollution control 
programs,
    (2) Additional emission limitations and schedules for compliance,
    (3) Measures to mitigate the impacts of construction activities,
    (4) Source retirement and replacement schedules,
    (5) Smoke management techniques for agricultural and forestry 
management purposes including such plans as currently exist within the 
State for these purposes, and
    (6) Enforceability of emission limitations and control measures.

[[Page 199]]

    (f) The plan must discuss the reasons why the above and other 
reasonable measures considered in the development of the long-term 
strategy were or were not adopted as part of the long-term strategy.
    (g) The State, in developing the long-term strategy, must take into 
account the effect of new sources, and the costs of compliance, the time 
necessary for compliance, the energy and nonair quality environmental 
impacts of compliance, and the remaining useful life of any affected 
existing source and equipment therein.

[45 FR 80089, Dec. 2, 1980, as amended at 64 FR 35764, 35774, July 1, 
1999]

    Effective Date Note:  At 64 FR 35764, 35774, July 1, 1999, 
Sec. 51.306 was amended in paragraph (a)(1) by removing ``Section 
300(a)'' and adding ``Sec. 51.300(a)'' and paragraph (c)(6) was amended 
by removing ``Section 303'' and adding ``Sec. 51.303'', and by revising 
the section heading, paragraph (a)(1), paragraph (c) introductory text, 
and paragraph (d), effective Aug. 30, 1999. For the convenience of the 
user, the superseded text follows:

Sec. 51.306  Long-term strategy.

    (a)(1) Each plan must include a long-term (10-15 years) strategy for 
making reasonable progress toward the national goal specified in section 
300(a). This strategy must cover any existing impairment the Federal 
Land Manager certifies to the State at least 6 months prior to plan 
submission, and any integral vista of which the Federal Land Manager 
notifies the State at least 6 months prior to plan submission.

                                * * * * *

    (c) The plan must provide for periodic review and revision, as 
appropriate, of the long-term strategy not less frequent than every 
three years. This review process must include consultation with the 
appropriate Federal Land Managers, and the State must provide a report 
to the public and the Administrator on progress toward the national 
goal. This report must include an assessment of:

                                * * * * *

    (d) The long-term strategy must provide for review of the impacts 
from any new major stationary source or major modifications on 
visibility in any mandatory Class I Federal area. This review of major 
stationary sources or major modifications must be in accordance with 
section 307, Sec. 51.24, Sec. 51.18 and any other binding guidance 
provided by the Agency insofar as these provisions pertain to protection 
of visibility in any mandatory Class I Federal areas.

                                * * * * *



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)(1)(D) or 
(E) 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 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.

[[Page 200]]

    (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, if it is identified in accordance with Sec. 51.304 
by the Federal Land Manager at least 12 months before submission of a 
complete permit application, except where the Federal Land Manager has 
provided notice and opportunity for public comment on the integral vista 
in which case the review must include impacts on any integral vista 
identified at least 6 months prior to submission of a complete permit 
application, unless the State determines under Sec. 51.304(d) that the 
identification was not in accordance with the identification criteria, 
or
    (2) That proposes to locate in an area classified as nonattainment 
under section 107(d)(1)(A), (B), or (C) 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]

    Effective Date Note:  At 64 FR 35765, 35774, July 1, 1999, 
Sec. 51.307 was amended in paragraph (b)(1) by removing ``Section 304'' 
and ``Section 304(d)'' and adding ``Sec. 51.304'' and ``Sec. 51.304(d)'' 
respectively; and paragraph (c) was amended by removing ``Section 
300(a)'' and adding ``Sec. 51.303(a)``; and revising paragraph (a) 
introductory text, (a)(2), and (c), effective Aug. 30, 1999. For the 
convenience of the user, the superseded text is set out as follows:

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)(1)(D) or 
(E) of the Clean Air Act, the State plan must, in any review under 
Sec. 51.24 with respect to visibility protection and analyses, provide 
for:

                                * * * * *

    (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. 51.24) 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

                                * * * * *

    (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. 51.24(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.  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.

                                * * * * *



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 paragraph (c) of this section and 
Sec. 51.309(c), each State identified in Sec. 51.300(b)(3) must submit 
an implementation plan for regional haze meeting the requirements of 
paragraphs (d) and (e) of this section by the following dates:
    (1) For any area designated as attainment or unclassifiable for the 
national ambient air quality standard (NAAQS) for fine particulate 
matter (PM2.5), the

[[Page 201]]

State must submit a regional haze implementation plan to EPA within 12 
months after the date of designation.
    (2) For any area designated as nonattainment for the 
PM2.5 NAAQS, the State must submit a regional haze 
implementation plan to EPA at the same time that the State's plan for 
implementation of the PM2.5 NAAQS must be submitted under 
section 172 of the CAA, that is, within 3 years after the area is 
designated as nonattainment, but not later than December 31, 2008.
    (c) Options for regional planning. If at the time the SIP for 
regional haze would otherwise be due, a State is working with other 
States to develop a coordinated approach to regional haze by 
participating in a regional planning process, the State may choose to 
defer addressing the core requirements for regional haze in paragraph 
(d) of this section and the requirements for BART in paragraph (e) of 
this section. If a State opts to do this, it must meet the following 
requirements:
    (1) The State must submit an implementation plan by the earliest 
date by which an implementation plan would be due for any area of the 
State under paragraph (b) of this section. This implementation plan must 
contain the following:
    (i) A demonstration of ongoing participation in a regional planning 
process to address regional haze, and an agreement by the State to 
continue participating with one or more other States in such a process 
for the development of this and future implementation plan revisions;
    (ii) A showing, based on available inventory, monitoring, or 
modeling information, that emissions from within the State contribute to 
visibility impairment in a mandatory Class I Federal Area outside the 
State, or that emissions from another State contribute to visibility 
impairment in any mandatory Class I Federal area within the State.
    (iii) A description of the regional planning process, including a 
list of the States which have agreed to work together to address 
regional haze in a region (i.e., the regional planning group), the 
goals, objectives, management, and decisionmaking structure of the 
regional planning group, deadlines for completing significant technical 
analyses and developing emission management strategies, and a schedule 
for State review and adoption of regulations implementing the 
recommendations of the regional group;
    (iv) A commitment by the State to submit an implementation plan 
revision addressing the requirements in paragraphs (d) and (e) of this 
section by the date specified in paragraph (c)(2) of this section. In 
addition, the State must commit to develop its plan revision in 
coordination with the other States participating in the regional 
planning process, and to fully address the recommendations of the 
regional planning group.
    (v) A list of all BART-eligible sources within the State.
    (2) The State must submit an implementation plan revision addressing 
the requirements in paragraphs (d) and (e) of this section by the latest 
date an area within the planning region would be required to submit an 
implementation plan under paragraph (b) of this section, but in any 
event, no later than December 31, 2008.
    (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

[[Page 202]]

I Federal area within the State, the State must:
    (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;

[[Page 203]]

    (ii) For an implementation plan that is submitted by 2003, the 
period for establishing baseline visibility conditions for the period of 
the first long-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)(A) 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; or
    (B) For all future implementation plan revisions, the number of 
deciviews by which current conditions, as calculated under paragraph 
(f)(1) of this section, 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)(3) 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 which 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:

[[Page 204]]

    (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;
    (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. This 
determination must be based on the following analyses:

[[Page 205]]

    (A) An analysis of the best system of continuous emission control 
technology available and associated emission reductions achievable for 
each BART-eligible source within the State subject to BART. 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 equipment in 
use at the source, and the remaining useful life of the source; and
    (B) An analysis of the degree of visibility improvement that would 
be achieved in each mandatory Class I Federal area as a result of the 
emission reductions achievable from all sources subject to BART located 
within the region that contributes to visibility impairment in the Class 
I area, based on the analysis conducted under paragraph (e)(1)(ii)(A) of 
this section.
    (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 an emissions trading program or 
other alternative measure rather than to require sources subject to BART 
to install, operate, and maintain BART. To do so, the State must 
demonstrate that this emissions trading program or other alternative 
measure will achieve greater reasonable progress than would be achieved 
through the installation and operation of BART. To make this 
demonstration, 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. This demonstration must be based on the 
following:
    (A) A list of all BART-eligible sources within the State.
    (B) 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. 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 equipment in use at the source, and 
the remaining useful life of the source. The best system of continuous 
emission control technology and the above factors may be determined on a 
source category basis. The State may elect to consider both source-
specific and category-wide information, as appropriate, in conducting 
its analysis.
    (C) An analysis of the degree of visibility improvement that would 
be achieved in each mandatory Class I Federal area as a result of the 
emission reductions achievable from all such sources subject to BART 
located within the region that contributes to visibility impairment in 
the Class I area, based on the analysis conducted under paragraph 
(e)(2)(i)(B) of this section.
    (ii) A demonstration that the emissions trading program or 
alternative measure will apply, at a minimum, to all BART-eligible 
sources in the State. Those sources having a federally enforceable 
emission limitation determined by the State and approved by EPA as 
meeting BART in accordance with Sec. 51.302(c) or paragraph (e)(1) of 
this section do not need to meet the requirements of the emissions 
trading

[[Page 206]]

program or alternative measure, but may choose to participate if they 
meet the requirements of the emissions trading program or alternative 
measure.
    (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(c) related to BART for reasonably attributable impairment 
from the pollutants covered under the emissions trading program or other 
alternative measure.
    (3) After a State has met the requirements for BART or implemented 
emissions trading program or other alternative measure that achieve more 
reasonable progress than the installation and operation of BART, BART-
eligible sources will be subject to the requirements of paragraph (d) of 
this section in the same manner as other sources.
    (4) 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) through (h).
    (f) Requirements for comprehensive periodic revisions of 
implementation plans for regional haze. Each State identified in 
Sec. 51.300(b)(3) must revise and submit its regional haze 
implementation plan revision to EPA by July 31, 2018 and every ten years 
thereafter. In each plan revision, the State must evaluate and reassess 
all of the elements required in paragraph (d) of this section, taking 
into account improvements in monitoring data collection and analysis 
techniques, control technologies, and other relevant factors. In 
evaluating and reassessing these elements, the State must address the 
following:
    (1) Current visibility conditions for the most impaired and least 
impaired days, and actual progress made towards natural conditions 
during the previous implementation period. The period for calculating 
current visibility conditions is the most recent five year period 
preceding the required date of the implementation plan submittal for 
which data are available. Current visibility conditions must be 
calculated based on the annual average level of visibility impairment 
for the most and least impaired days for each of these five years. 
Current visibility conditions are the average of these annual values.
    (2) The effectiveness of the long-term strategy for achieving 
reasonable progress goals over the prior implementation period(s); and
    (3) Affirmation of, or revision to, the reasonable progress goal in 
accordance with the procedures set forth in paragraph (d)(1) of this 
section. If the State established a reasonable progress goal for the 
prior period which provided a slower rate of progress than that needed 
to attain natural conditions by the year 2064, the State must evaluate 
and determine the reasonableness, based on the factors in paragraph 
(d)(1)(i)(A) of this section, of additional measures that could be 
adopted to achieve the degree of visibility improvement projected by the 
analysis contained in the first implementation plan described in 
paragraph (d)(1)(i)(B) of this section.
    (g) Requirements for periodic reports describing progress towards 
the reasonable progress goals. Each State identified in 
Sec. 51.300(b)(3) must submit a report to the Administrator every 5 
years 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 which

[[Page 207]]

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 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. 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 and least impaired days expressed in terms of 
5-year averages of these annual values.
    (i) The current visibility conditions for the most impaired and 
least impaired days;
    (ii) The difference between current visibility conditions for the 
most impaired and least impaired days and baseline visibility 
conditions;
    (iii) The change in visibility impairment for the most impaired and 
least impaired days over the past 5 years;
    (4) 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.
    (5) 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.
    (6) 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.
    (7) A review of the State's visibility monitoring strategy and any 
modifications to the strategy as necessary.
    (h) Determination of the adequacy of existing implementation plan. 
At the same time the State is required to submit any 5-year 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 negative 
declaration that further 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 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

[[Page 208]]

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 and at least 60 days prior to 
holding any public hearing on an implementation plan (or plan revision) 
for regional haze required by this subpart. 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 of the reasonable progress 
goal and on the development and implementation of strategies to address 
visibility impairment.
    (3) In developing any implementation plan (or plan revision), 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 5-year 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]

    Effective Date Note:  At 64 FR 35765, July 1, 1999, Sec. 51.308 was 
added, effective Aug. 30, 1999.



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 years 2003 to 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, as supplemented by an 
approvable Annex to the Commission Report as required by paragraph (f) 
of this section. 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.
    (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.

[[Page 209]]

    (4) Fire means wildfire, wildland fire (including prescribed natural 
fire), prescribed fire, and agricultural burning conducted and occurring 
on Federal, State, and private wildlands and farmlands.
    (5) Milestone means an average percentage reduction in emissions, 
expressed in tons per year, for a given year or for a period of up to 5 
years ending in that year, compared to a 1990 actual emissions baseline.
    (6) Mobile Source Emission Budget means the lowest level of VOC, 
NOX, SO2 elemental and organic carbon, and fine 
particles which are projected to occur in any area within the transport 
region from which mobile source emissions are determined to contribute 
significantly to visibility impairment in any of the 16 Class I areas.
    (7) Geographic enhancement means a method, procedure, or process to 
allow a broad regional strategy, such as a milestone or backstop market 
trading program designed to achieve greater reasonable progress than 
BART for regional haze, to accommodate BART for reasonably attributable 
impairment.
    (c) Implementation Plan Schedule. Each Transport Region State may 
meet the requirements of Sec. 51.308(b) through (e) by electing to 
submit an implementation plan that complies with the requirements of 
this section. Each Transport Region State must submit an implementation 
plan addressing regional haze visibility impairment in the 16 Class I 
areas no later than December 31, 2003. A Transport Region State that 
elects not to submit an implementation plan that complies with the 
requirements of this section (or whose plan does not comply with all of 
the requirements of 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.
    (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 
for the entire time period between December 31, 2003 and December 31, 
2018.
    (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 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

[[Page 210]]

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) Monitoring and reporting of sulfur dioxide emissions. The plan 
submission must include provisions requiring the monitoring and 
reporting of actual stationary source sulfur dioxide emissions within 
the State. The monitoring and reporting data must be sufficient to 
determine whether a 13 percent reduction in actual stationary source 
sulfur dioxide emissions has occurred between the years 1990 and 2000, 
and whether milestones required by paragraph (f)(1)(i) of this section 
have been achieved for the transport region. The plan submission must 
provide for reporting of these data by the State to the Administrator. 
Where procedures developed under paragraph (f)(1)(ii) of this section 
and agreed upon by the State include reporting to a regional planning 
organization, the plan submission must provide for reporting to the 
regional planning body in addition to the Administrator.
    (ii) Criteria and procedures for a market trading program. The plan 
must include the criteria and procedures for activating a market trading 
program or other program consistent with paragraph (f)(1)(i) of this 
section if an applicable regional milestone is exceeded, procedures for 
operation of the program, and implementation plan assessments and 
provisions for implementation plan assessments of the program in the 
years 2008, 2013, and 2018.
    (iii) Provisions for activating a market trading program. Provisions 
to activate the market trading program or other program within 12 months 
after the emissions for the region are determined to exceed the 
applicable emission reduction milestone, and to assure that all affected 
sources are in compliance with allocation and other requirements within 
5 years after the emissions for the region are determined to exceed the 
applicable emission reduction milestone.
    (iv) Provisions for market trading program compliance reporting. If 
the market trading program has been activated, the plan submission must 
include provisions requiring the State to provide annual reports 
assuring that all sources are in compliance with applicable requirements 
of the market trading program.
    (v) Provisions for stationary source NOX and PM. The plan 
submission must include a report which assesses emissions control 
strategies for stationary source NOX and PM, and the degree 
of visibility improvement that would result from such strategies. In the 
report, the State must evaluate and discuss the need to establish 
emission milestones for NOX and PM to avoid any net increase 
in these pollutants from stationary sources within the transport region, 
and to support potential future development and implementation of a 
multipollutant and possibly multisource market-based program. The plan 
submission must provide for an implementation plan revision, containing 
any necessary long-term strategies and BART requirements for stationary 
source PM and NOX (including enforceable limitations, 
compliance schedules, and other measures) by no later than December 31, 
2008.
    (5) Mobile sources. The plan submission must provide for:
    (i) Statewide inventories of current annual emissions and projected 
future annual emissions of VOc, NOX, 
SO2, elemental carbon, organic carbon, and fine particles 
from mobile sources for the years 2003 to 2018. The future year 
inventories must include projections for the year 2005, or an 
alternative year that is determined by the State to represent the year 
during which mobile source emissions will be at their lowest levels 
within the State.
    (ii) A determination whether mobile source emissions in any areas of 
the State contribute significantly to visibility impairment in any of 
the 16 Class I Areas, based on the statewide

[[Page 211]]

inventory of current and projected mobile source emissions.
    (iii) For States with areas in which mobile source emissions are 
found to contribute significantly to visibility impairment in any of the 
16 Class I areas:
    (A) The establishment and documentation of a mobile source emissions 
budget for any such area, including provisions requiring the State to 
restrict the annual VOC, NOX, SO2, elemental and 
organic carbon, and/or fine particle mobile source emissions to their 
projected lowest levels, to implement measures to achieve the budget or 
cap, and to demonstrate compliance with the budget.
    (B) An emission tracking system providing for reporting of annual 
mobile source emissions from the State in the periodic implementation 
plan revisions required by paragraph (d)(10) of this section. The 
emission tracking system must be sufficient to determine the States' 
contribution toward the Commission's objective of reducing emissions 
from mobile sources by 2005 or an alternate year that is determined by 
the State to represent the year during which mobile source emissions 
will be at their lowest levels within the State, and to ensure that 
mobile source emissions do not increase thereafter.
    (iv) 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.

[[Page 212]]

    (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 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. Each Transport Region 
State must submit to the Administrator periodic reports in the years 
2008, 2013, and 2018. The 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.
    (i) The report 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 which 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 reports 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.

[[Page 213]]

    (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 any 5-year 
progress report to EPA in accordance with paragaph (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:
    (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.
    (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) Annex to the Commission Report. (1) A Transport Region State may 
choose to comply with the provisions of this section and by doing so 
shall satisfy the requirements of Sec. 51.308(b) through

[[Page 214]]

(e) only if the Grand Canyon Visibility Transport Commission (or a 
regional planning body formed to implement the Commission 
recommendations) submits a satisfactory annex to the Commission Report 
no later than October 1, 2000. To be satisfactory, the Annex must 
contain the following elements:
    (i) The annex must contain quantitative emission reduction 
milestones for stationary source sulfur dioxide emissions for the 
reporting years 2003, 2008, 2013 and 2018. The milestones must provide 
for steady and continuing emission reductions for the 2003-2018 time 
period consistent with the Commission's definition of reasonable 
progress, its goal of 50 to 70 percent reduction in sulfur dioxide 
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 deficiencies which will be 
due in the years 2008, 2013, and 2018. The emission reduction milestones 
must be shown to provide for greater reasonable progress than would be 
achieved by application of best available retrofit technology (BART) 
pursuant to Sec. 51.308(e)(2) and would be approvable in lieu of BART.
    (ii) The annex must contain documentation of the market trading 
program or other programs to be implemented pursuant to paragraph (d)(4) 
of this section if current programs and voluntary measures are not 
sufficient to meet the required emission reduction milestones. This 
documentation must include model rules, memoranda of understanding, and 
other documentation describing in detail how emission reduction progress 
will be monitored, what conditions will require the market trading 
program to be activated, how allocations will be performed, and how the 
program will operate.
    (2) The Commission may elect, at the same time it submits the annex, 
to make recommendations intended to demonstrate reasonable progress for 
other mandatory Class I areas (beyond the original 16) within the 
Transport Region States, including the technical and policy 
justification for these additional mandatory Class I Federal areas in 
accordance with the provisions of paragraph (g) of this section.
    (3) The EPA will publish the annex upon receipt. If EPA finds that 
the annex meets the requirements of paragraph (f)(1) of this section and 
assures reasonable progress, then, after public notice and comment, will 
amend the requirements of paragraph (d)(4) of this section to 
incorporate the provisions of the annex within 1 year after EPA receives 
the annex. If EPA finds that the annex does not meet the requirements of 
paragraph (f)(1) of this section, or does not assure reasonable 
progress, or if EPA finds that the annex is not received, then each 
Transport Region State must submit an implementation plan for regional 
haze meeting all of the requirements of Sec. 51.308.
    (4) In accordance with the provisions under paragraph (f)(1) of this 
section, the annex may include a geographic enhancement to the program 
provided for in paragraph (d)(4) of this section to address the 
requirement under Sec. 51.302(c) related to Best Available Retrofit 
Technology for reasonably attributable impairment from the pollutants 
covered by the milestones or the backstop market trading program. The 
geographic enhancement program may include an appropriate level of 
reasonably attributable impairment which may require additional emission 
reductions over and above those achieved under the milestones defines in 
paragraph (f)(1)(i) of this section.
    (g) Additional Class I areas. The following submittals must be made 
by Transport Region States implementing the provisions of this section 
as the basis for demonstrating reasonable progress for additional Class 
I areas in the Transport Region States. 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) In the plan submitted for the 16 Class I areas no later than 
December 31, 2003, a declaration indicating whether other Class I areas 
will be addressed under Sec. 51.308 or paragraphs (g)(2) and (3) of this 
section.

[[Page 215]]

    (2) In a plan submitted no later than December 31, 2008, provide 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.
    (3) In a plan submitted no later than December 31, 2008, provide 
revisions to the plan submitted under paragraph (c) of this section, 
including provisions to establish reasonable progress goals and 
implement any additional measures necessary to demonstrate reasonable 
progress for the additional mandatory Federal Class I areas. These 
revisions must comply with the provisions of Sec. 51.308(d)(1) through 
(4).
    (4) The following provisions apply for Transport Region States 
establishing reasonable progress goals and adopting any additional 
measures for Class I areas other than the 16 Class I areas under 
paragraphs (g)(2) and (3) of this section.
    (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 (f) 
of this section, it is shown that greater reasonable progress will be 
achieved for these 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)(3) 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 no air 
quality environmental impacts of compliance, or the remaining useful 
life of any existing source subject to such requirements.

[64 FR 35769, July 1, 1999]

    Effective Date Note: At 64 FR 35769, July 1, 1999, Sec. 51.309 was 
added, effective Aug. 30, 1999.



                           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.

    On an annual (calendar year) basis beginning with calendar year 
1979, the State agency shall report to the Administrator (through the 
appropriate Regional Office) information as specified in Secs. 51.323 
through 51.326. Reports must be submitted by July 1 of each year for 
data collected and actions which took place during the period January 1 
to December 31 of the previous year.



Sec. 51.322  Sources subject to emissions reporting.

    (a) Point sources subject to the annual emissions reporting 
requirements of Sec. 51.321 are defined as follows:
    (1) For particulate matter, PM10, sulfur oxides, VOC and 
nitrogen oxides, any facility that actually emits a total of 181.4 
metric tons (200 tons) per year or more of any one pollutant. For 
particulate matter emissions, the reporting requirement ends with the 
reporting of calendar year 1987 emissions. For PM10 
emissions, the reporting requirement begins with the reporting of 
calendar year 1988 emissions.

[[Page 216]]

    (2) For carbon monoxide, any facility that actually emits a total of 
1814 metric tons (2000 tons) per year or more.
    (3) For lead or lead compounds measured as elemental lead, any 
facility that actually emits a total of 4.5 metric tons (5 tons) per 
year or more.
    (b) Annual emissions reporting requirements apply only to emissions 
of each pollutant from any individual emission point within the facility 
that emits:
    (1) For particulate matter, PM10, sulfur oxides, VOC and 
nitrogen oxides. 22.7 metric tons (25 tons) per year or more. For 
particulate matter, the reporting requirement ends with the reporting of 
calendar year 1987 emissions. For PM10, the reporting 
requirement begins with the reporting of calendar year 1988 emissions.
    (2) For carbon monoxide, 227 metric tons (250 tons) per year or 
more.
    (3) For lead or lead compounds measured as elemental lead, 4.5 
metric tons (5 tons) per year or more.

[44 FR 27569, May 10, 1979, as amended at 44 FR 65070, Nov. 9, 1979; 52 
FR 24714, July 1, 1987; 64 FR 7462, Feb. 12, 1999]



Sec. 51.323  Reportable emissions data and information.

    (a) The State shall submit in the annual report the following 
emissions data and information:
    (1) Emissions of particulate matter (PM10), sulfur oxides, carbon 
monoxide, nitrogen oxides, VOC and lead or lead compounds measured as 
elemental lead as specified by the AIRS Facility Subsystem User's Guide 
AF2 ``AFS Data Coding'' (EPA-454/B-94-004) point source coding form,
    (2) [Reserved]
    (3) Emissions of PM 2.5 as will be specified in a future guideline.
    (b) Such emissions data and information specified in paragraph (a) 
of this section must be submitted to the AIRS/AFS database via either 
online data entry or batch update system.
    (c) The emissions data and information specified by paragraph (a) of 
this section must be submitted in the annual report for any point source 
for which one or more of the following conditions occurs:
    (1) A source achieves compliance at any time within the reporting 
period with any regulation of an applicable plan,
    (2) A new or modified source receives approval to construct during 
the reporting period or begins operating during the reporting period,
    (3) A source ceases operations during the reporting period, or
    (4) A source's emissions have changed more than 5% from the most 
recently submitted emissions data.
    (d) If, as determined by the State and the Regional Administrator, 
the emissions from any point source have not changed more than 5% from 
the most recently submitted emissions data, the State shall update the 
year of record of the previously reported data and information specified 
by paragraph (a) of this section.

[44 FR 27569, May 10, 1979, as amended at 52 FR 24714, July 1, 1987; 64 
FR 7463, Feb. 12, 1999]



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
    (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.

[[Page 217]]



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 (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

[[Page 218]]

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 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

[[Page 219]]

the area is redesignated to attainment status, until the State submits 
and EPA approves a maintenance plan, under section 175A, which 
convincingly demonstrates that the area can maintain the relevant 
standard for the maintenance period without benefit of the emission 
reductions attributable to the I/M program. The State shall commit to 
fully implement and enforce the program throughout such period, and, at 
a minimum, for the purposes of SIP approval, legislation authorizing the 
program shall not sunset prior to the attainment deadline.
    (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]



Sec. 51.351  Enhanced I/M performance standard.

    (a) 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.
    (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 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 2.0 gpm NOX;
    (vii) Emission standards for 1981-1985 model year vehicles of 1.2% 
CO, and 220 ppm 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

[[Page 220]]

carbon dioxide (CO2) on vehicles subject to a steady-state 
test (as described in appendix B of this subpart S).
    (8) Emission control device inspections. Visual inspection of the 
catalyst and fuel inlet restrictor on all 1984 and later model year 
vehicles.
    (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 programs shall be shown to obtain 
the same or lower emission levels as the model program by 2000 for ozone 
nonattainment areas and 2001 for CO nonattainment areas, and for severe 
and extreme ozone nonattainment areas, on each applicable milestone and 
attainment deadline, thereafter. Milestones for NOX shall be 
the same as for ozone.
    (b) On-road testing. The performance standard shall include on-road 
testing 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) and (g) of this section. Specific 
requirements are listed in Sec. 51.371 of this subpart.
    (c) On-board diagnostics (OBD). The performance standard shall 
include inspection of all 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.
    (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-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. Except as provided in 
paragraph (g) 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

[[Page 221]]

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).
    (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 shall be shown to 
obtain the same or lower emission levels as the model program described 
in this paragraph by 2000 for ozone nonattainment areas and 2001 for CO 
nonattainment areas, and for severe and extreme ozone nonattainment 
areas, on each applicable milestone and attainment deadline, thereafter. 
Milestones for NOX shall be the same as for ozone.
    (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.

[[Page 222]]

    (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 2000 
for ozone nonattainment areas and 2001 for CO nonattainment areas, and 
for severe and extreme ozone nonattainment areas, on each applicable 
milestone and attainment deadline, thereafter. Milestones for 
NOX shall be the same as for ozone.
    (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 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 dates. 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 by January 1, 2000, 2003, 2006, and 2007. Equality of 
substituted emission reductions to the benefits of the low enhanced 
performance standard must be demonstrated for the same evaluation dates.

[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]



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.

[[Page 223]]

    (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). The performance standard shall 
include inspection of all 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.
    (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 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.

[57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996; 63 
FR 24433, May 4, 1998]



Sec. 51.353  Network type and program evaluation.

    Enhanced I/M programs shall be operated in a centralized test-only 
format, unless the State can demonstrate that a decentralized program is 
equally effective in achieving the enhanced I/M performance standard. 
Basic I/M programs can be centralized, decentralized, or a hybrid at the 
State's discretion, but shall be demonstrated to achieve the same 
emission reduction as the program described in Sec. 51.352 of this 
subpart.
    (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 
equivalent to a centralized, test-only system. States may allow such 
stations to engage in the sale of refreshments for the use of employees 
and customers waiting at the station and may fulfill other functions 
typically carried out by the State such as renewal of vehicle 
registration and driver's licenses, or tax and fee collections.
    (b) Case-by-case equivalency. (1) Credits for test-and-repair 
networks, i.e., those not meeting the requirements of

[[Page 224]]

paragraph (a) of this section, are assumed to be 50% less than those for 
a test-only network for the tailpipe emission test, purge test, 
evaporative system integrity test, catalyst check, and gas cap check; 
and 75% less for the evaporative canister checks, PCV check, and air 
system checks. Smaller reductions in credits for the various test 
protocols may be claimed if a State can demonstrate to the satisfaction 
of the Administrator that based on past performance with the specific 
test-type and inspection standards employed, its test-and-repair system 
will exceed these levels. At a minimum, such a demonstration shall 
include:
    (i) Surveys that assess the effectiveness of repairs performed on 
vehicles that failed the tailpipe emission test and evaporative system 
tests;
    (ii) In programs including tampering checks, measurement of actual 
tampering rates, their change over time, and the change attributable to 
finding and fixing such tampering as opposed to deterrence effects; and
    (iii) The results of undercover surveys of inspector effectiveness 
as it relates to identifying vehicles that need repair.
    (2) In the case of hybrid systems, which may be implemented in basic 
I/M areas, including both test-only and test-and-repair facilities, full 
credit shall apply to the portion of the fleet initially tested and 
subsequently retested at a test-only facility meeting the requirements 
of paragraph (a) of this section, and to the portion of the fleet 
initially tested and failed at a test-and-repair facility but 
subsequently passing a comprehensive retest at a test-only facility 
meeting those same requirements. The credit loss assumptions described 
in paragraph (b)(1) of this section shall apply to the portion of the 
fleet initially passed at a test-and-repair facility, and to the portion 
initially failed at a test-only facility and retested at a test-and-
repair facility.
    (3) Areas operating test-and-repair networks or hybrid networks may, 
in the future, claim greater effectiveness than described in paragraph 
(b)(1) of this section, if a demonstration of greater effectiveness is 
made to the satisfaction of the Administrator using the program 
evaluation protocol described in paragraph (c) of this section.
    (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 
November 30, 1998.
    (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

[[Page 225]]

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]



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, 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

[[Page 226]]

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 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.

[[Page 227]]

    (5) Special exemptions may be permitted for certain subject vehicles 
provided a demonstration is made that the performance standard will be 
met.
    (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.



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 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, or fast pass/fail algorithms.
    (4) Tests involving measurement shall be performed with program-
approved equipment that has been calibrated accordingly 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.
    (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.
    (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.

[[Page 228]]

    (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.
    (ii) The system shall be pressurized to 140.5 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 240 seconds of mass emission measurement using a constant 
volume sampler while the vehicle is driven through a computer-monitored 
driving cycle on a dynamometer with inertial weight settings appropriate 
for the weight of the vehicle. The driving cycle shall include 
acceleration, deceleration, and idle operating modes as specified in 
appendix E to this subpart. The 240 second sequence may be ended earlier 
using 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. Inspection of the on-board 
diagnostic system shall be according to the procedure described in 40 
CFR 85.2222, at a minimum.
    (13) Approval of alternative tests. Alternative test procedures may 
be approved if the Administrator finds that--
    (i) Such procedures are in accordance with good engineering 
practice, including errors of commission (at cutpoints corresponding to 
equivalent emission reductions) no higher than the tests they would 
replace;
    (ii) Such procedures show a correlation with the Federal Test 
Procedure (with respect to their ability to detect high emitting 
vehicles and ensure their effective repair) equal to or better than the 
tests they would replace; and
    (iii) Such procedures would produce equivalent emission reductions 
in combination with other program elements.
    (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 and 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 transient 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) of this subpart.
    (i) Steady-state short tests. The steady-state short test emission 
standards for 1981 and later model year light duty vehicles and light 
duty trucks shall be at least as stringent as those in appendix C to 
this subpart.
    (ii) Transient test. Transient test emission standards shall be 
established for HC, CO, CO2, and NOX for subject 
vehicles based on model year and vehicle type.
    (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

[[Page 229]]

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 140.5 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 diagnostics 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, 2001.
    (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.
    (1) Vehicles with engines other than the engine originally installed 
by the 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]



Sec. 51.358  Test equipment.

    Computerized test systems are required for performing any 
measurement on subject vehicles.
    (a) Performance features of computerized test systems. The test 
equipment shall be certified by the program to

[[Page 230]]

meet the requirements contained in appendix D to this subpart, and newly 
acquired 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.
    (2) At a minimum, emission test equipment:
    (i) Shall be automated to the highest degree commercially available 
to minimize the potential for intentional fraud and/or human error;
    (ii) Shall be secure from tampering and/or abuse;
    (iii) Shall be based upon written specifications; and
    (iv) Shall be capable of simultaneously sampling dual exhaust 
vehicles.
    (3) The vehicle owner or driver shall be provided with a computer-
generated record of test results, including all of the items listed in 
40 CFR part 85, subpart W as being required on the test record. 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 of tests performed, including emission tests, visual 
checks for the presence of emission control components, and functional, 
evaporative system checks;
    (v) The applicable test standards;
    (vi) The test results, including exhaust concentrations and pass/
fail results for each mode measured, pass/fail results for evaporative 
system checks, and which emission control devices inspected were passed, 
failed, or not applicable;
    (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 tailpipe emission test, information 
on the possible causes of the specific pattern of high emission levels 
found during the test.
    (b) Functional characteristics of computerized test systems. The 
test system is composed of emission measurement devices and other motor 
vehicle test equipment controlled by a computer.
    (1) The test system shall automatically:
    (i) Make a pass/fail decision for all measurements;
    (ii) Record test data to an electronic medium;
    (iii) Conduct regular self-testing of recording accuracy;
    (iv) Perform electrical calibration and system integrity checks 
before each test, as applicable; and
    (v) Initiate system lockouts for:
    (A) Tampering with security aspects of the test system;
    (B) Failing to conduct or pass periodic calibration or leak checks;
    (C) Failing to conduct or pass the constant volume sampler flow rate 
check (if applicable);
    (D) Failing to conduct or pass any of the dynamometer checks, 
including coast-down, roll speed and roll distance, power absorption 
capability, and inertia weight selection checks (if applicable);
    (E) Failing to conduct or pass the pressure monitoring device check 
(if applicable);
    (F) Failing to conduct or pass the purge flow metering system check 
(if applicable); and
    (G) A full data recording medium or one that does not pass a 
cyclical redundancy check.
    (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.
    (3) The test system shall insure accurate data collection by 
limiting, cross-checking, and/or confirming manual data entry.
    (4) On-board diagnostic test equipment requirements. The test 
equipment used

[[Page 231]]

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. The specifications shall 
describe the emission analysis 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]



Sec. 51.359  Quality control.

    Quality control measures shall insure that emission measurement 
equipment is calibrated and maintained properly, and that inspection, 
calibration records, and control charts are accurately created, recorded 
and maintained.
    (a) General requirements. (1) The practices described in this 
section and in appendix A to this subpart shall be followed, at a 
minimum. Alternatives or exceptions to these procedures or frequencies 
may be approved by the Administrator based on a demonstration, including 
control chart analysis, of equivalent performance.
    (2) Preventive maintenance on all inspection equipment necessary to 
insure accurate and repeatable operation shall be performed on a 
periodic basis.
    (3) Computerized analyzers shall automatically record quality 
control check information, lockouts, attempted tampering, and any other 
recordable circumstances which should be monitored to insure quality 
control (e.g., service calls).
    (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 equivalent 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 equivalent performance.
    (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

[[Page 232]]

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]



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 model year cutoffs and the associated dollar limits shall 
be in full effect no later than January 1, 1998. 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

[[Page 233]]

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 
Secs. 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 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]



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

[[Page 234]]

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 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.

[[Page 235]]

    (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 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.

[[Page 236]]

    (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 
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:

[[Page 237]]

    (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;
    (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; through automated or 
redundant data entry; and, through automated analysis for valid alpha-
numeric sequences of the vehicle identification number (VIN), 
certificate number, or license plate number;
    (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.



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 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

[[Page 238]]

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) 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) Software-based, computerized 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;
    (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; and
    (11) A check of the purge flow metering system.

[[Page 239]]

    (d) Auditor training and proficiency. (1) Auditors shall be formally 
trained and knowledgeable in:
    (i) The use of analyzers;
    (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.



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.
    (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

[[Page 240]]

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.
    (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;
    (2) Inspection station and inspector numbers;
    (3) Test system number;
    (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;

[[Page 241]]

    (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 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; and
    (25) Results of the on-board diagnostic check expressed as a pass or 
fail along with the diagnostic trouble codes revealed.
    (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.

[ 57 FR 52987, Nov. 5, 1992, as amended at 61 FR 40945, Aug. 6, 1996]



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 the emissions test initially;
    (ii) Failing each emission control component check initially;
    (iii) Failing the evaporative system functional and integrity checks 
initially;
    (iv) Failing the first retest for tailpipe emissions;
    (v) Passing the first retest for tailpipe emissions;
    (vi) Initially failed vehicles passing the second or subsequent 
retest for tailpipe emissions;
    (vii) Initially failed vehicles passing each emission control 
component check on the first or subsequent retest by component;
    (viii) Initially failed vehicles passing the evaporative system 
functional and integrity checks on the first or subsequent retest by 
component;
    (ix) Initially failed vehicles receiving a waiver;
    (x) Vehicles with no known final outcome (regardless of reason);
    (xi) Passing the on-board diagnostic check and failing the I/M 
emission test;
    (xii) Failing the on-board diagnostic check and passing the I/M 
emission test;
    (xiii) Passing both the on-board diagnostic check and I/M emission 
test;
    (xiv) Failing both the on-board diagnostic check and I/M emission 
test;
    (xv) Passing the on-board diagnostic check and failing the I/M 
evaporative test;
    (xvi) Failing the on-board diagnostic check and passing the I/M 
evaporative test;
    (xvii) Passing both the on-board diagnostic check and I/M 
evaporative test;
    (xviii) Failing both the on-board diagnostic check and I/M 
evaporative test;

[[Page 242]]

    (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 the emission test;
    (ii) Conducted with the vehicle set to fail the component check;
    (iii) Conducted with the vehicle set to fail the evaporative system 
checks;
    (iv) Conducted with the vehicle set to fail any combination of two 
or more of the above checks;
    (v) Resulting in a false pass for emissions;
    (vi) Resulting in a false pass for component checks;
    (vii) Resulting in a false pass for the evaporative system check; 
and
    (viii) Resulting in a false pass for any combination of two or more 
of the above checks;
    (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
    (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;

[[Page 243]]

    (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]



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;
    (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;
    (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

[[Page 244]]

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, to properly utilize equipment and to follow other 
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.



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 
software-generated, interpretive diagnostic information based on 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.



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

[[Page 245]]

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;
    (3) Utilization of diagnostic information on systematic or repeated 
failures observed in the transient emission test and the evaporative 
system functional checks; 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.



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 ``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

[[Page 246]]

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 the measurement 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, including 
any vehicles that may be subject to the follow-up inspection provisions 
of paragraph (a)(4) of this section, each inspection cycle.
    (3) The on-road testing program shall provide information about the 
emission performance of in-use vehicles, by measuring on-road emissions 
through the use of remote sensing devices or roadside pullovers 
including tailpipe emission testing. 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

[[Page 247]]

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.
    (3) Emission reduction credit for on-road testing programs shall be 
granted for a program designed to obtain significant emission reductions 
over and above those already predicted to be achieved by other aspects 
of the I/M program. The SIP shall include technical support for the 
claimed additional emission reductions.



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) States shall submit a SIP revision by November 15, 1992 which 
includes the schedule required in paragraph (a)(1) of this section and a 
formal commitment from the Governor to the adoption and implementation 
of an I/M program meeting all requirements of this subpart.
    (2) A SIP revision, including all necessary legal authority and the 
items specified in (a)(1) through (a)(8) of this section, shall be 
submitted no later than November 15, 1993.
    (3) States shall revise SIPS as EPA develops further regulations. 
Revisions to incorporate on-board diagnostic checks in the I/M program 
shall be submitted by August 6, 1998.
    (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

[[Page 248]]

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]



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.
    (b) For areas newly required to implement basic I/M after 
promulgation of this subpart (as a result of failure to attain, 
reclassification, or redesignation) decentralized programs shall be 
fully implemented within one year of obtaining legal authority. 
Centralized programs shall be fully implemented within two years of 
obtaining legal authority. More implementation time may be approved by 
the Administrator if an enhanced I/M program is implemented.
    (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).

[[Page 249]]

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) In the case of areas newly required to implement enhanced I/M 
after promulgation of this subpart (as a result of failure to attain, 
reclassification, or nonattainment designation) enhanced I/M shall be 
implemented within 24 months of obtaining legal authority.
    (e) Legal authority for the implementing agency or agencies to 
implement and enforce an I/M program consistent with this subpart shall 
be obtained from the State legislature or local governing body in the 
first legislative session after November 5, 1992, or after being newly 
required to implement or upgrade an I/M program as in paragraph (b) or 
(c) of this section, including sessions already in progress if at least 
21 days remain before the final bill submittal deadline.
    (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, 2001.

[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]

 Appendix A to Subpart S--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 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

[[Page 250]]

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:
[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.

[[Page 251]]

    (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 (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.

[[Page 252]]

    (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 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]

                Appendix B to Subpart S--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.

[[Page 253]]

    (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.
    (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

[[Page 254]]

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:
    (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

[[Page 255]]

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=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

[[Page 256]]

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 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

[[Page 257]]

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.
    (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.

[[Page 258]]

    (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:
    (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.

[[Page 259]]

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 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.

[[Page 260]]

    (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.
    (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.

[[Page 261]]

    (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 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:

[[Page 262]]

    (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).
    (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:

[[Page 263]]

    (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 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:

[[Page 264]]

    (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 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]

       Appendix C to Subpart S--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.

[[Page 265]]

    (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%.

       Appendix D to Subpart S--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 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, %......................  0-4.0       2.................................  0.1% CO2.
NO..................................  1ppm NO.
RPM.................................  1rpm.
 

    (3) Response time. The response time from the probe to the display 
for HC, CO, and CO2 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.
    (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]

          Appendix E to Subpart S--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

[[Page 267]]

 
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
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

[[Page 268]]

 
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]



   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



Sec. 51.390  Implementation plan revision.

    (a) States with areas subject to this subpart and part 93, subpart 
A, of this chapter must submit to the EPA and DOT a revision to their 
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. This revision is to be 
submitted 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). Further revisions to the 
implementation plan required by amendments to part 93, subpart A, of 
this chapter must be submitted within 12 months of the date of 
publication of such final amendments. EPA will provide DOT with a 30-day 
comment period before taking action to approve or disapprove the 
submission. 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.

[[Page 269]]

    (b) 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. Following EPA approval of the State conformity provisions (or a 
portion thereof) in a revision to the applicable implementation plan, 
conformity determinations would be governed by the approved (or approved 
portion of the) State criteria and procedures. The Federal conformity 
regulations contained in part 93, subpart A, of this chapter would apply 
only for 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.
    (c) The implementation plan revision required by this section must 
meet all of the requirements of part 93, subpart A, of this chapter.
    (d) In order for EPA to approve the implementation plan revision 
submitted to EPA and DOT under this subpart, the plan must address all 
requirements of part 93, subpart A, of this chapter in a manner which 
gives them full legal effect. In particular, the revision shall 
incorporate the provisions of the following sections of part 93, subpart 
A, of this chapter 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 
the following sections of this chapter: Secs. 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.

[62 FR 43801, Aug. 15, 1997]



                 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

[[Page 270]]

(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, 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

[[Page 271]]

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, 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.

[[Page 272]]

    (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.
    (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:

[[Page 273]]

    (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.
    (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.

[[Page 274]]

    (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 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

[[Page 275]]

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.
    (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.

[[Page 276]]

    (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 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

[[Page 277]]

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 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.

[[Page 278]]



Sec. 51.850  Prohibition.

    (a) No department, agency or instrumentality of the Federal 
Government shall engage in, support in any way or provide financial 
assistance for, license or permit, or approve any activity which does 
not conform to an applicable implementation plan.
    (b) A Federal agency must make a determination that a Federal action 
conforms to the applicable implementation plan in accordance with the 
requirements of this subpart before the action is taken.
    (c) Paragraph (b) of this section does not include Federal actions 
where either:
    (1) A National Environmental Policy Act (NEPA) analysis was 
completed as evidenced by a final environmental assessment (EA), 
environmental impact statement (EIS), or finding of no significant 
impact (FONSI) that was prepared prior to January 31, 1994;
    (2)(i) Prior to January 31, 1994, an EA was commenced or a contract 
was awarded to develop the specific environmental analysis;
    (ii) Sufficient environmental analysis is completed by March 15, 
1994 so that the Federal agency may determine that the Federal action is 
in conformity with the specific requirements and the purposes of the 
applicable SIP pursuant to the agency's affirmative obligation under 
section 176(c) of the Clean Air Act (Act); and
    (iii) A written determination of conformity under section 176(c) of 
the Act has been made by the Federal agency responsible for the Federal 
action by March 15, 1994.
    (d) Notwithstanding any provision of this subpart, a determination 
that an action is in conformance with the applicable implementation plan 
does not exempt the action from any other requirements of the applicable 
implementation plan, the NEPA, or the Act.



Sec. 51.851  State Implementation Plan (SIP) revision.

    (a) Each State must 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 subpart. The 
State must submit the conformity provisions within 12 months after 
November 30, 1993 or within 12 months of an area's designation to 
nonattainment, whichever date is later.
    (b) The Federal conformity rules under this subpart and 40 CFR part 
93, in addition to any existing applicable State requirements, establish 
the conformity criteria and procedures necessary to meet the Act 
requirements until such time as the required conformity SIP revision is 
approved by EPA. A State's conformity provisions must contain criteria 
and procedures that are no less stringent than the requirements 
described in this subpart. A State may establish more stringent 
conformity criteria and procedures only if they apply equally to non-
Federal as well as Federal entities. Following EPA approval of the State 
conformity provisions (or a portion thereof) in a revision to the 
applicable SIP, the approved (or approved portion of the) State criteria 
and procedures would govern conformity determinations and the Federal 
conformity regulations contained in 40 CFR part 93 would apply only for 
the portion, if any, of the State's conformity provisions that is not 
approved by EPA. In addition, any previously applicable SIP requirements 
relating to conformity remain enforceable until the State revises its 
SIP to specifically remove them from the SIP and that revision is 
approved by EPA.



Sec. 51.852  Definitions.

    Terms used but not defined in this part shall have the meaning given 
them by the Act and EPA's regulations, (40 CFR chapter I), in that order 
of priority.
    Affected Federal land manager means the Federal agency or the 
Federal official charged with direct responsibility for management of an 
area designated as Class I under the Act (42 U.S.C. 7472) that is 
located within 100 km of the proposed Federal action.
    Applicable implementation plan or applicable SIP means the portion 
(or portions) of the SIP or most recent revision thereof, which has been 
approved under section 110 of the Act, or promulgated under section 
110(c) of the Act

[[Page 279]]

(Federal implementation plan), or promulgated or approved pursuant to 
regulations promulgated under section 301(d) of the Act and which 
implements the relevant requirements of the Act.
    Areawide air quality modeling analysis means an assessment on a 
scale that includes the entire nonattainment or maintenance area which 
uses an air quality dispersion model to determine the effects of 
emissions on air quality.
    Cause or contribute to a new violation means a Federal action that:
    (1) Causes a new violation of a national ambient air quality 
standard (NAAQS) at a location in a nonattainment or maintenance area 
which would otherwise not be in violation of the standard during the 
future period in question if the Federal action were not taken; or
    (2) Contributes, in conjunction with other reasonably foreseeable 
actions, to a new violation of a NAAQS at a location in a nonattainment 
or maintenance area in a manner that would increase the frequency or 
severity of the new violation.
    Caused by, as used in the terms ``direct emissions'' and ``indirect 
emissions,'' means emissions that would not otherwise occur in the 
absence of the Federal action.
    Criteria pollutant or standard means any pollutant for which there 
is established a NAAQS at 40 CFR part 50.
    Direct emissions means those emissions of a criteria pollutant or 
its precursors that are caused or initiated by the Federal action and 
occur at the same time and place as the action.
    Emergency means a situation where extremely quick action on the part 
of the Federal agencies involved is needed and where the timing of such 
Federal activities makes it impractical to meet the requirements of this 
subpart, such as natural disasters like hurricanes or earthquakes, civil 
disturbances such as terrorist acts, and military mobilizations.
    Emissions budgets are those portions of the applicable SIP's 
projected emissions inventories that describe the levels of emissions 
(mobile, stationary, area, etc.) that provide for meeting reasonable 
further progress milestones, attainment, and/or maintenance for any 
criteria pollutant or its precursors.
    Emissions offsets, for purposes of Sec. 51.858, are emissions 
reductions which are quantifiable, consistent with the applicable SIP 
attainment and reasonable further progress demonstrations, surplus to 
reductions required by, and credited to, other applicable SIP 
provisions, enforceable at both the State and Federal levels, and 
permanent within the timeframe specified by the program.
    Emissions that a Federal agency has a continuing program 
responsibility for means emissions that are specifically caused by an 
agency carrying out its authorities, and does not include emissions that 
occur due to subsequent activities, unless such activities are required 
by the Federal agency. Where an agency, in performing its normal program 
responsibilities, takes actions itself or imposes conditions that result 
in air pollutant emissions by a non-Federal entity taking subsequent 
actions, such emissions are covered by the meaning of a continuing 
program responsibility.
    EPA means the Environmental Protection Agency.
    Federal action means any activity engaged in by a department, 
agency, or instrumentality of the Federal Government, or any activity 
that a department, agency or instrumentality of the Federal Government 
supports in any way, provides financial assistance for, licenses, 
permits, or approves, other than activities related to transportation 
plans, programs, and projects developed, funded, or approved under title 
23 U.S.C. or the Federal Transit Act (49 U.S.C. 1601 et seq.). Where the 
Federal action is a permit, license, or other approval for some aspect 
of a non-Federal undertaking, the relevant activity is the part, 
portion, or phase or the non-Federal undertaking that requires the 
Federal permit, license, or approval.
    Federal agency means, for purposes of this subpart, a Federal 
department, agency, or instrumentality of the Federal Government.
    Increase the frequency or severity of any existing violation of any 
standard in any area means to cause a nonattainment area to exceed a 
standard more

[[Page 280]]

often or to cause a violation at a greater concentration than previously 
existed and/or would otherwise exist during the future period in 
question, if the project were not implemented.
    Indirect emissions means those emissions of a criteria pollutant or 
its precursors that:
    (1) Are caused by the Federal action, but may occur later in time 
and/or may be farther removed in distance from the action itself but are 
still reasonably foreseeable; and
    (2) The Federal agency can practicably control and will maintain 
control over due to a continuing program responsibility of the Federal 
agency.
    Local air quality modeling analysis means an assessment of localized 
impacts on a scale smaller than the entire nonattainment or maintenance 
area, including, for example, congested roadway intersections and 
highways or transit terminals, which uses an air quality dispersion 
model to determine the effects of emissions on air quality.
    Maintenance area means an area with a maintenance plan approved 
under section 175A of the Act.
    Maintenance plan means a revision to the applicable SIP, meeting the 
requirements of section 175A of the Act.
    Metropolitan Planning Organization (MPO) is that organization 
designated as being responsible, together with the State, for conducting 
the continuing, cooperative, and comprehensive planning process under 23 
U.S.C. 134 and 49 U.S.C. 1607.
    Milestone has the meaning given in sections 182(g)(1) and 189(c)(1) 
of the Act.
    National ambient air quality standards (NAAQS) are those standards 
established pursuant to section 109 of the Act and include standards for 
carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), 
ozone, particulate matter (PM-10), and sulfur dioxide (SO2).
    NEPA is the National Environmental Policy Act of 1969, as amended 
(42 U.S.C. 4321 et seq.).
    Nonattainment Area (NAA) means an area designated as nonattainment 
under section 107 of the Act and described in 40 CFR part 81.
    Precursors of a criteria pollutant are:
    (1) For ozone, nitrogen oxides (NOX), unless an area is 
exempted from NOX requirements under section 182(f) of the 
Act, and volatile organic compounds (VOC); and
    (2) For PM-10, those pollutants described in the PM-10 nonattainment 
area applicable SIP as significant contributors to the PM-10 levels.
    Reasonably foreseeable emissions are projected future indirect 
emissions that are identified at the time the conformity determination 
is made; the location of such emissions is known and the emissions are 
quantifiable, as described and documented by the Federal agency based on 
its own information and after reviewing any information presented to the 
Federal agency.
    Regional water and/or wastewater projects include construction, 
operation, and maintenance of water or wastewater conveyances, water or 
wastewater treatment facilities, and water storage reservoirs which 
affect a large portion of a nonattainment or maintenance area.
    Regionally significant action means a Federal action for which the 
direct and indirect emissions of any pollutant represent 10 percent or 
more of a nonattainment or maintenance area's emissions inventory for 
that pollutant.
    Total of direct and indirect emissions means the sum of direct and 
indirect emissions increases and decreases caused by the Federal action; 
i.e., the ``net'' emissions considering all direct and indirect 
emissions. The portion of emissions which are exempt or presumed to 
conform under Sec. 51.853, (c), (d), (e), or (f) are not included in the 
``total of direct and indirect emissions.'' The ``total of direct and 
indirect emissions'' includes emissions of criteria pollutants and 
emissions of precursors of criteria pollutants.



Sec. 51.853  Applicability.

    (a) Conformity determinations for Federal actions related to 
transportation plans, programs, and projects developed, funded, or 
approved under title 23 U.S.C. or the Federal Transit Act (49 U.S.C. 
1601 et seq.) must meet the procedures and criteria of 40 CFR part 51, 
subpart T, in lieu of the procedures set forth in this subpart.
    (b) For Federal actions not covered by paragraph (a) of this 
section, a conformity determination is required for

[[Page 281]]

each pollutant where the total of direct and indirect emissions in a 
nonattainment or maintenance area caused by a Federal action would equal 
or exceed any of the rates in paragraphs (b)(1) or (2) of this section.
    (1) For purposes of paragraph (b) of this section, the following 
rates apply in nonattainment areas (NAAs):

------------------------------------------------------------------------
                                                                  Tons/
                                                                   year
------------------------------------------------------------------------
Ozone (VOC's or NOX):
  Serious NAA's................................................       50
  Severe NAA's.................................................       25
  Extreme NAA's................................................       10
  Other ozone NAA's outside an ozone transport region..........      100
Marginal and moderate NAA's inside an ozone transport region:
    VOC........................................................       50
    NOX........................................................      100
Carbon monoxide: All NAA's.....................................      100
SO2 or NO2: All NAA's..........................................      100
PM-10:
  Moderate NAA's...............................................      100
  Serious NAA's................................................       70
Pb: All NAA's..................................................       25
------------------------------------------------------------------------

    (2) For purposes of paragraph (b) of this section, the following 
rates apply in maintenance areas:

------------------------------------------------------------------------
                                                                  Tons/
                                                                   year
------------------------------------------------------------------------
Ozone (NOX), SO2 or NO2: All maintenance areas.................      100
Ozone (VOC's):
  Maintenance areas inside an ozone transport region...........       50
  Maintenance areas outside an ozone transport region..........      100
Carbon monoxide: All maintenance areas.........................      100
PM-10: All maintenance areas...................................      100
Pb: All maintenance areas......................................       25
------------------------------------------------------------------------

    (c) The requirements of this subpart shall not apply to:
    (1) Actions where the total of direct and indirect emissions are 
below the emissions levels specified in paragraph (b) of this section.
    (2) The following actions which would result in no emissions 
increase or an increase in emissions that is clearly de minimis:
    (i) Judicial and legislative proceedings.
    (ii) Continuing and recurring activities such as permit renewals 
where activities conducted will be similar in scope and operation to 
activities currently being conducted.
    (iii) Rulemaking and policy development and issuance.
    (iv) Routine maintenance and repair activities, including repair and 
maintenance of administrative sites, roads, trails, and facilities.
    (v) Civil and criminal enforcement activities, such as 
investigations, audits, inspections, examinations, prosecutions, and the 
training of law enforcement personnel.
    (vi) Administrative actions such as personnel actions, 
organizational changes, debt management or collection, cash management, 
internal agency audits, program budget proposals, and matters relating 
to the administration and collection of taxes, duties and fees.
    (vii) The routine, recurring transportation of materiel and 
personnel.
    (viii) Routine movement of mobile assets, such as ships and 
aircraft, in home port reassignments and stations (when no new support 
facilities or personnel are required) to perform as operational groups 
and/or for repair or overhaul.
    (ix) Maintenance dredging and debris disposal where no new depths 
are required, applicable permits are secured, and disposal will be at an 
approved disposal site.
    (x) Actions, such as the following, with respect to existing 
structures, properties, facilities and lands where future activities 
conducted will be similar in scope and operation to activities currently 
being conducted at the existing structures, properties, facilities, and 
lands; for example, relocation of personnel, disposition of federally-
owned existing structures, properties, facilities, and lands, rent 
subsidies, operation and maintenance cost subsidies, the exercise of 
receivership or conservatorship authority, assistance in purchasing 
structures, and the production of coins and currency.
    (xi) The granting of leases, licenses such as for exports and trade, 
permits, and easements where activities conducted will be similar in 
scope and operation to activities currently being conducted.
    (xii) Planning, studies, and provision of technical assistance.
    (xiii) Routine operation of facilities, mobile assets and equipment.
    (xiv) Transfers of ownership, interests, and titles in land, 
facilities, and

[[Page 282]]

real and personal properties, regardless of the form or method of the 
transfer.
    (xv) The designation of empowerment zones, enterprise communities, 
or viticultural areas.
    (xvi) Actions by any of the Federal banking agencies or the Federal 
Reserve Banks, including actions regarding charters, applications, 
notices, licenses, the supervision or examination of depository 
institutions or depository institution holding companies, access to the 
discount window, or the provision of financial services to banking 
organizations or to any department, agency or instrumentality of the 
United States.
    (xvii) Actions by the Board of Governors of the Federal Reserve 
System or any Federal Reserve Bank to effect monetary or exchange rate 
policy.
    (xviii) Actions that implement a foreign affairs function of the 
United States.
    (xix) Actions (or portions thereof) associated with transfers of 
land, facilities, title, and real properties through an enforceable 
contract or lease agreement where the delivery of the deed is required 
to occur promptly after a specific, reasonable condition is met, such as 
promptly after the land is certified as meeting the requirements of the 
Comprehensive Environmental Response, Compensation, and Liability Act 
(CERCLA), and where the Federal agency does not retain continuing 
authority to control emissions associated with the lands, facilities, 
title, or real properties.
    (xx) Transfers of real property, including land, facilities, and 
related personal property from a Federal entity to another Federal 
entity and assignments of real property, including land, facilities, and 
related personal property from a Federal entity to another Federal 
entity for subsequent deeding to eligible applicants.
    (xxi) Actions by the Department of the Treasury to effect fiscal 
policy and to exercise the borrowing authority of the United States.
    (3) The following actions where the emissions are not reasonably 
foreseeable:
    (i) Initial Outer Continental Shelf lease sales which are made on a 
broad scale and are followed by exploration and development plans on a 
project level.
    (ii) Electric power marketing activities that involve the 
acquisition, sale and transmission of electric energy.
    (4) Actions which implement a decision to conduct or carry out a 
conforming program such as prescribed burning actions which are 
consistent with a conforming land management plan.
    (d) Notwithstanding the other requirements of this subpart, a 
conformity determination is not required for the following Federal 
actions (or portion thereof):
    (1) The portion of an action that includes major new or modified 
stationary sources that require a permit under the new source review 
(NSR) program (section 173 of the Act) or the prevention of significant 
deterioration (PSD) program (title I, part C of the Act).
    (2) Actions in response to emergencies or natural disasters such as 
hurricanes, earthquakes, etc., which are commenced on the order of hours 
or days after the emergency or disaster and, if applicable, which meet 
the requirements of paragraph (e) of this section.
    (3) Research, investigations, studies, demonstrations, or training 
(other than those exempted under paragraph (c)(2) of this section), 
where no environmental detriment is incurred and/or, the particular 
action furthers air quality research, as determined by the State agency 
primarily responsible for the applicable SIP.
    (4) Alteration and additions of existing structures as specifically 
required by new or existing applicable environmental legislation or 
environmental regulations (e.g., hush houses for aircraft engines and 
scrubbers for air emissions).
    (5) Direct emissions from remedial and removal actions carried out 
under the Comprehensive Environmental Response, Compensation and 
Liability Act (CERCLA) and associated regulations to the extent such 
emissions either comply with the substantive requirements of the PSD/NSR 
permitting program or are exempted from other environmental regulation 
under the

[[Page 283]]

provisions of CERCLA and applicable regulations issued under CERCLA.
    (e) Federal actions which are part of a continuing response to an 
emergency or disaster under paragraph (d)(2) of this section and which 
are to be taken more than 6 months after the commencement of the 
response to the emergency or disaster under paragraph (d)(2) of this 
section are exempt from the requirements of this subpart only if:
    (1) The Federal agency taking the actions makes a written 
determination that, for a specified period not to exceed an additional 6 
months, it is impractical to prepare the conformity analyses which would 
otherwise be required and the actions cannot be delayed due to 
overriding concerns for public health and welfare, national security 
interests and foreign policy commitments; or
    (2) For actions which are to be taken after those actions covered by 
paragraph (e)(1) of this section, the Federal agency makes a new 
determination as provided in paragraph (e)(1) of this section.
    (f) Notwithstanding other requirements of this subpart, actions 
specified by individual Federal agencies that have met the criteria set 
forth in either paragraph (g)(1) or (g)(2) of this section and the 
procedures set forth in paragraph (h) of this section are presumed to 
conform, except as provided in paragraph (j) of this section.
    (g) The Federal agency must meet the criteria for establishing 
activities that are presumed to conform by fulfilling the requirements 
set forth in either paragraph (g)(1) or (g)(2) of this section:
    (1) The Federal agency must clearly demonstrate using methods 
consistent with this subpart that the total of direct and indirect 
emissions from the type of activities which would be presumed to conform 
would not:
    (i) Cause or contribute to any new violation of any standard in any 
area;
    (ii) Interfere with provisions in the applicable SIP for maintenance 
of any standard;
    (iii) Increase the frequency or severity of any existing violation 
of any standard in any area; or
    (iv) Delay timely attainment of any standard or any required interim 
emission reductions or other milestones in any area including, where 
applicable, emission levels specified in the applicable SIP for purposes 
of:
    (A) A demonstration of reasonable further progress;
    (B) A demonstration of attainment; or
    (C) A maintenance plan; or
    (2) The Federal agency must provide documentation that the total of 
direct and indirect emissions from such future actions would be below 
the emission rates for a conformity determination that are established 
in paragraph (b) of this section, based, for example, on similar actions 
taken over recent years.
    (h) In addition to meeting the criteria for establishing exemptions 
set forth in paragraphs (g)(1) or (g)(2) of this section, the following 
procedures must also be complied with to presume that activities will 
conform:
    (1) The Federal agency must identify through publication in the 
Federal Register its list of proposed activities that are presumed to 
conform and the basis for the presumptions;
    (2) The Federal agency must notify the appropriate EPA Regional 
Office(s), State and local air quality agencies and, where applicable, 
the agency designated under section 174 of the Act and the MPO and 
provide at least 30 days for the public to comment on the list of 
proposed activities presumed to conform;
    (3) The Federal agency must document its response to all the 
comments received and make the comments, response, and final list of 
activities available to the public upon request; and
    (4) The Federal agency must publish the final list of such 
activities in the Federal Register.
    (i) Notwithstanding the other requirements of this subpart, when the 
total of direct and indirect emissions of any pollutant from a Federal 
action does not equal or exceed the rates specified in paragraph (b) of 
this section, but represents 10 percent or more of a nonattainment or 
maintenance area's total emissions of that pollutant, the

[[Page 284]]

action is defined as a regionally significant action and the 
requirements of Sec. 51.850 and Secs. 51.855 through 51.860 shall apply 
for the Federal action.
    (j) Where an action otherwise presumed to conform under paragraph 
(f) of this section is a regionally significant action or does not in 
fact meet one of the criteria in paragraph (g)(1) of this section, that 
action shall not be presumed to conform and the requirements of 
Sec. 51.850 and Secs. 51.855 through 51.860 shall apply for the Federal 
action.
    (k) The provisions of this subpart shall apply in all nonattainment 
and maintenance areas.



Sec. 51.854  Conformity analysis.

    Any Federal department, agency, or instrumentality of the Federal 
Government taking an action subject to this subpart must make its own 
conformity determination consistent with the requirements of this 
subpart. In making its conformity determination, a Federal agency must 
consider comments from any interested parties. Where multiple Federal 
agencies have jurisdiction for various aspects of a project, a Federal 
agency may choose to adopt the analysis of another Federal agency or 
develop its own analysis in order to make its conformity determination.



Sec. 51.855  Reporting requirements.

    (a) A Federal agency making a conformity determination under 
Sec. 51.858 must provide to the appropriate EPA Regional Office(s), 
State and local air quality agencies and, where applicable, affected 
Federal land managers, the agency designated under section 174 of the 
Act and the MPO a 30 day notice which describes the proposed action and 
the Federal agency's draft conformity determination on the action.
    (b) A Federal agency must notify the appropriate EPA Regional 
Office(s), State and local air quality agencies and, where applicable, 
affected Federal land managers, the agency designated under section 174 
of the Clean Air Act and the MPO within 30 days after making a final 
conformity determination under Sec. 51.858.



Sec. 51.856  Public participation.

    (a) Upon request by any person regarding a specific Federal action, 
a Federal agency must make available for review its draft conformity 
determination under Sec. 51.858 with supporting materials which describe 
the analytical methods and conclusions relied upon in making the 
applicability analysis and draft conformity determination.
    (b) A Federal agency must make public its draft conformity 
determination under Sec. 51.858 by placing a notice by prominent 
advertisement in a daily newspaper of general circulation in the area 
affected by the action and by providing 30 days for written public 
comment prior to taking any formal action on the draft determination. 
This comment period may be concurrent with any other public involvement, 
such as occurs in the NEPA process.
    (c) A Federal agency must document its response to all the comments 
received on its draft conformity determination under Sec. 51.858 and 
make the comments and responses available, upon request by any person 
regarding a specific Federal action, within 30 days of the final 
conformity determination.
    (d) A Federal agency must make public its final conformity 
determination under Sec. 51.858 for a Federal action by placing a notice 
by prominent advertisement in a daily newspaper of general circulation 
in the area affected by the action within 30 days of the final 
conformity determination.



Sec. 51.857  Frequency of conformity determinations.

    (a) The conformity status of a Federal action automatically lapses 5 
years from the date a final conformity determination is reported under 
Sec. 51.855, unless the Federal action has been completed or a 
continuous program has been commenced to implement that Federal action 
within a reasonable time.
    (b) Ongoing Federal activities at a given site showing continuous 
progress are not new actions and do not require periodic 
redeterminations so long as such activities are within the scope of the 
final conformity determination reported under Sec. 51.855.

[[Page 285]]

    (c) If, after the conformity determination is made, the Federal 
action is changed so that there is an increase in the total of direct 
and indirect emissions above the levels in Sec. 51.853(b), a new 
conformity determination is required.



Sec. 51.858  Criteria for determining conformity of general Federal actions.

    (a) An action required under Sec. 51.853 to have a conformity 
determination for a specific pollutant, will be determined to conform to 
the applicable SIP if, for each pollutant that exceeds the rates in 
Sec. 51.853(b), or otherwise requires a conformity determination due to 
the total of direct and indirect emissions from the action, the action 
meets the requirements of paragraph (c) of this section, and meets any 
of the following requirements:
    (1) For any criteria pollutant, the total of direct and indirect 
emissions from the action are specifically identified and accounted for 
in the applicable SIP's attainment or maintenance demonstration;
    (2) For ozone or nitrogen dioxide, the total of direct and indirect 
emissions from the action are fully offset within the same nonattainment 
or maintenance area through a revision to the applicable SIP or a 
similarly enforceable measure that effects emission reductions so that 
there is no net increase in emissions of that pollutant;
    (3) For any criteria pollutant, except ozone and nitrogen dioxide, 
the total of direct and indirect emissions from the action meet the 
requirements:
    (i) Specified in paragraph (b) of this section, based on areawide 
air quality modeling analysis and local air quality modeling analysis; 
or
    (ii) Meet the requirements of paragraph (a)(5) of this section and, 
for local air quality modeling analysis, the requirement of paragraph 
(b) of this section;
    (4) For CO or PM-10--
    (i) Where the State agency primarily responsible for the applicable 
SIP determines that an areawide air quality modeling analysis is not 
needed, the total of direct and indirect emissions from the action meet 
the requirements specified in paragraph (b) of this section, based on 
local air quality modeling analysis; or
    (ii) Where the State agency primarily responsible for the applicable 
SIP determines that an areawide air quality modeling analysis is 
appropriate and that a local air quality modeling analysis is not 
needed, the total of direct and indirect emissions from the action meet 
the requirements specified in paragraph (b) of this section, based on 
areawide modeling, or meet the requirements of paragraph (a)(5) of this 
section; or
    (5) For ozone or nitrogen dioxide, and for purposes of paragraphs 
(a)(3)(ii) and (a)(4)(ii) of this section, each portion of the action or 
the action as a whole meets any of the following requirements:
    (i) Where EPA has approved a revision to an area's attainment or 
maintenance demonstration after 1990 and the State makes a determination 
as provided in paragraph (a)(5)(i)(A) of this section or where the State 
makes a commitment as provided in paragraph (a)(5)(i)(B) of this 
section:
    (A) The total of direct and indirect emissions from the action (or 
portion thereof) is determined and documented by the State agency 
primarily responsible for the applicable SIP to result in a level of 
emissions which, together with all other emissions in the nonattainment 
(or maintenance) area, would not exceed the emissions budgets specified 
in the applicable SIP;
    (B) The total of direct and indirect emissions from the action (or 
portion thereof) is determined by the State agency responsible for the 
applicable SIP to result in a level of emissions which, together with 
all other emissions in the nonattainment (or maintenance) area, would 
exceed an emissions budget specified in the applicable SIP and the State 
Governor or the Governor's designee for SIP actions makes a written 
commitment to EPA which includes the following:
    (1) A specific schedule for adoption and submittal of a revision to 
the SIP which would achieve the needed emission reductions prior to the 
time emissions from the Federal action would occur;
    (2) Identification of specific measures for incorporation into the 
SIP which

[[Page 286]]

would result in a level of emissions which, together with all other 
emissions in the nonattainment or maintenance area, would not exceed any 
emissions budget specified in the applicable SIP;
    (3) A demonstration that all existing applicable SIP requirements 
are being implemented in the area for the pollutants affected by the 
Federal action, and that local authority to implement additional 
requirements has been fully pursued;
    (4) A determination that the responsible Federal agencies have 
required all reasonable mitigation measures associated with their 
action; and
    (5) Written documentation including all air quality analyses 
supporting the conformity determination;
    (C) Where a Federal agency made a conformity determination based on 
a State commitment under paragraph (a)(5)(i)(B) of this section, such a 
State commitment is automatically deemed a call for a SIP revision by 
EPA under section 110(k)(5) of the Act, effective on the date of the 
Federal conformity determination and requiring response within 18 months 
or any shorter time within which the State commits to revise the 
applicable SIP;
    (ii) The action (or portion thereof), as determined by the MPO, is 
specifically included in a current transportation plan and 
transportation improvement program which have been found to conform to 
the applicable SIP under 40 CFR part 51, subpart T, or 40 CFR part 93, 
subpart A;
    (iii) The action (or portion thereof) fully offsets its emissions 
within the same nonattainment or maintenance area through a revision to 
the applicable SIP or an equally enforceable measure that effects 
emission reductions equal to or greater than the total of direct and 
indirect emissions from the action so that there is no net increase in 
emissions of that pollutant;
    (iv) Where EPA has not approved a revision to the relevant SIP 
attainment or maintenance demonstration since 1990, the total of direct 
and indirect emissions from the action for the future years (described 
in Sec. 51.859(d)) do not increase emissions with respect to the 
baseline emissions:
    (A) The baseline emissions reflect the historical activity levels 
that occurred in the geographic area affected by the proposed Federal 
action during:
    (1) Calendar year 1990;
    (2) The calendar year that is the basis for the classification (or, 
where the classification is based on multiple years, the most 
representative year), if a classification is promulgated in 40 CFR part 
81; or
    (3) The year of the baseline inventory in the PM-10 applicable SIP;
    (B) The baseline emissions are the total of direct and indirect 
emissions calculated for the future years (described in Sec. 51.859(d)) 
using the historic activity levels (described in paragraph (a)(5)(iv)(A) 
of this section) and appropriate emission factors for the future years; 
or
    (v) Where the action involves regional water and/or wastewater 
projects, such projects are sized to meet only the needs of population 
projections that are in the applicable SIP.
    (b) The areawide and/or local air quality modeling analyses must:
    (1) Meet the requirements in Sec. 51.859; and
    (2) Show that the action does not:
    (i) Cause or contribute to any new violation of any standard in any 
area; or
    (ii) Increase the frequency or severity of any existing violation of 
any standard in any area.
    (c) Notwithstanding any other requirements of this section, an 
action subject to this subpart may not be determined to conform to the 
applicable SIP unless the total of direct and indirect emissions from 
the action is in compliance or consistent with all relevant requirements 
and milestones contained in the applicable SIP, such as elements 
identified as part of the reasonable further progress schedules, 
assumptions specified in the attainment or maintenance demonstration, 
prohibitions, numerical emission limits, and work practice requirements.
    (d) Any analyses required under this section must be completed, and 
any mitigation requirements necessary for a finding of conformity must 
be identified before the determination of conformity is made.

[[Page 287]]



Sec. 51.859  Procedures for conformity determinations of general Federal actions.

    (a) The analyses required under this subpart must be based on the 
latest planning assumptions.
    (1) All planning assumptions must be derived from the estimates of 
population, employment, travel, and congestion most recently approved by 
the MPO, or other agency authorized to make such estimates, where 
available.
    (2) Any revisions to these estimates used as part of the conformity 
determination, including projected shifts in geographic location or 
level of population, employment, travel, and congestion, must be 
approved by the MPO or other agency authorized to make such estimates 
for the urban area.
    (b) The analyses required under this subpart must be based on the 
latest and most accurate emission estimation techniques available as 
described below, unless such techniques are inappropriate. If such 
techniques are inappropriate and written approval of the EPA Regional 
Administrator is obtained for any modification or substitution, they may 
be modified or another technique substituted on a case-by-case basis or, 
where appropriate, on a generic basis for a specific Federal agency 
program.
    (1) For motor vehicle emissions, the most current version of the 
motor vehicle emissions model specified by EPA and available for use in 
the preparation or revision of SIPs in that State must be used for the 
conformity analysis as specified in paragraphs (b)(1) (i) and (ii) of 
this section:
    (i) The EPA must publish in the Federal Register a notice of 
availability of any new motor vehicle emissions model; and
    (ii) A grace period of three months shall apply during which the 
motor vehicle emissions model previously specified by EPA as the most 
current version may be used. Conformity analyses for which the analysis 
was begun during the grace period or no more than 3 years before the 
Federal Register notice of availability of the latest emission model may 
continue to use the previous version of the model specified by EPA.
    (2) For non-motor vehicle sources, including stationary and area 
source emissions, the latest emission factors specified by EPA in the 
``Compilation of Air Pollutant Emission Factors (AP-42)''\1\ must be 
used for the conformity analysis unless more accurate emission data are 
available, such as actual stack test data from stationary sources which 
are part of the conformity analysis.
---------------------------------------------------------------------------

    \1\ Copies may be obtained from the Technical Support Division of 
OAQPS, EPA, MD-14, Research Triangle Park, NC 27711.
---------------------------------------------------------------------------

    (c) The air quality modeling analyses required under this subpart 
must be based on the applicable air quality models, data bases, and 
other requirements specified in the most recent version of the 
``Guideline on Air Quality Models (Revised)'' (1986), including 
supplements (EPA publication no. 450/2-78-027R) \2\, unless:
---------------------------------------------------------------------------

    \2\ See footnote 1 at Sec. 51.859(b)(2).
---------------------------------------------------------------------------

    (1) The guideline techniques are inappropriate, in which case the 
model may be modified or another model substituted on a case-by-case 
basis or, where appropriate, on a generic basis for a specific Federal 
agency program; and
    (2) Written approval of the EPA Regional Administrator is obtained 
for any modification or substitution.
    (d) The analyses required under this subpart, except 
Sec. 51.858(a)(1), must be based on the total of direct and indirect 
emissions from the action and must reflect emission scenarios that are 
expected to occur under each of the following cases:
    (1) The Act mandated attainment year or, if applicable, the farthest 
year for which emissions are projected in the maintenance plan;
    (2) The year during which the total of direct and indirect emissions 
from the action is expected to be the greatest on an annual basis; and
    (3) any year for which the applicable SIP specifies an emissions 
budget.



Sec. 51.860  Mitigation of air quality impacts.

    (a) Any measures that are intended to mitigate air quality impacts 
must be identified and the process for implementation and enforcement of 
such measures must be described, including

[[Page 288]]

an implementation schedule containing explicit timelines for 
implementation.
    (b) Prior to determining that a Federal action is in conformity, the 
Federal agency making the conformity determination must obtain written 
commitments from the appropriate persons or agencies to implement any 
mitigation measures which are identified as conditions for making 
conformity determinations.
    (c) Persons or agencies voluntarily committing to mitigation 
measures to facilitate positive conformity determinations must comply 
with the obligations of such commitments.
    (d) In instances where the Federal agency is licensing, permitting 
or otherwise approving the action of another governmental or private 
entity, approval by the Federal agency must be conditioned on the other 
entity meeting the mitigation measures set forth in the conformity 
determination.
    (e) When necessary because of changed circumstances, mitigation 
measures may be modified so long as the new mitigation measures continue 
to support the conformity determination. Any proposed change in the 
mitigation measures is subject to the reporting requirements of 
Sec. 51.856 and the public participation requirements of Sec. 51.857.
    (f) The implementation plan revision required in Sec. 51.851 shall 
provide that written commitments to mitigation measures must be obtained 
prior to a positive conformity determination and that such commitments 
must be fulfilled.
    (g) After a State revises its SIP to adopt its general conformity 
rules and EPA approves that SIP revision, any agreements, including 
mitigation measures, necessary for a conformity determination will be 
both State and federally enforceable. Enforceability through the 
applicable SIP will apply to all persons who agree to mitigate direct 
and indirect emissions associated with a Federal action for a conformity 
determination.

                        Appendixes A-K [Reserved]

    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 g/m 3 (0.3 p.p.m.), 24-hour 
average.
PM10--350 g/m\3\, 24-hour average.
CO--17 mg/m 3 (15 p.p.m.), 8-hour average.
Ozone (O2)=400 g/m 3 (0.2 ppm)-hour 
average.
NO2-1130 g/m 3 (0.6 p.p.m.), 1-hour 
average, 282 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:


[[Page 289]]


SO2--1,600 g/m 3 (0.6 p.p.m.), 24-hour 
average.
PM10--420 g/m\3\, 24-hour average.
CO--34 mg/m 3 (30 p.p.m.), 8-hour average.
Ozone (O3)--800 g/m 3 (0.4 p.p.m.), 1-
hour average.
NO2--2,260 g/m 3 (1.2 ppm)--1-hour 
average; 565g/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 g/m 3 (0.8 p.p.m.), 24-hour 
average.
    PM10--500 g/m\3\, 24-hour average.
CO--46 mg/m 3 (40 p.p.m.), 8-hour average.
Ozone (O3)--1,000 g/m 3 (0.5 p.p.m.), 1-
hour average.
NO2-3,000 g/m 3 (1.6 ppm), 1-hour 
average; 750 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 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.

[[Page 290]]

   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.

------------------------------------------------------------------------
      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.

[[Page 291]]

 
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.
------------------------------------------------------------------------

                   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.

[[Page 292]]



------------------------------------------------------------------------
      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.
------------------------------------------------------------------------

(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]

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 Emissions (Constant 
Sampling Rate Procedure).
Method 202--Determination of Condensible Particulate Emissions From 
Stationary Sources
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

    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.
    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.
    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.

         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 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.

[[Page 293]]

    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 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 
(p), orifice differential pressure (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.

[[Page 294]]

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 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.
    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  H@, 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

[[Page 295]]

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 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 H and 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 
(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 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 (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 p 
and stack temperature, select the appropriate 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 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 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

[[Page 296]]

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.
    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 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

[[Page 297]]

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 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 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 m. A suggested procedure is to vary the 
cyclone flow rate while keeping a constant particle size of 10 
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 () for the 
replicate measurements of Ec as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.018


[[Page 298]]


if  exceeds 0.10, repeat the replicate runs.
    5.7.5.4  Using the cyclone flow rate that produces D50 
for 10 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 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

    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 
() for the replicate measurements. If  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 
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 m 
and 15 m, one of which shall be 10 m. All sizes must 
be within 0.5 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.
 = Gas density, g/cm\3\.
dcyc = Diameter of cyclone inlet, cm.
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 m.
[GRAPHIC] [TIFF OMITTED] TC08NO91.069

where:

Q = Cyclone flow rate for a cut size of 10 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.

[[Page 299]]

    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, 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).
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)]}.
YT = Total LFE linear calibration constant, dscm/min (dscf/
min).
 PT = Pressure differential across total LFE, mm 
H2 O, (in. H2 O).
 = Total sampling time, min.
cyc = Viscosity of mixed cyclone gas, micropoise.
LFE = Viscosity of gas laminar flow elements, micropoise.
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:
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:

[[Page 300]]

[GRAPHIC] [TIFF OMITTED] TC08NO91.026

where 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.
[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 m  D50 11 
m and 90  I  110, the results are 
acceptable. If D50 is greater than 11 m, the 
Administrator may accept the results. If D50 is less than 9.0 
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 301]]




[[Page 302]]





[[Page 303]]





[[Page 304]]





[[Page 305]]





[[Page 306]]



                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
                              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.............   =   ______
  H@, 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 (H) for velocity head of stack 
          gas (p):
          [GRAPHIC] [TIFF OMITTED] TC08NO91.072
          

[[Page 307]]



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:
  LFE=152.418+0.2552 Tm+3.2355   =   ______
   x 10-5 Tm2+0.53147 (%O2).
Viscosity of dry stack gas:
  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


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 gasLFE,poise.   =   ______
Absolute pressure upstream of LFE,        =   ______
 PPLEin. Hg.
Calibration data:......................
  Nozzle diameter, Dn, in..............   =   ______
  Pitot coefficient, Cp................   =   ______

[[Page 308]]

 
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
                                             
                                             [GRAPHIC] [TIFF OMITTED] TC08NO91.037
                                             
                                             [GRAPHIC] [TIFF OMITTED] TC08NO91.038
                                             
    Pressure head for recycle LFE:
    [GRAPHIC] [TIFF OMITTED] TC08NO91.039
    

[[Page 309]]




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)_____________________
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.........................  .......  .......  .......
                                                                --------

[[Page 310]]

 
  Total particulate weight...................  .......  .......  .......
                                                                --------
------------------------------------------------------------------------

                                                                 
                                                                 

[[Page 311]]


 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).......  m........  101
                                                       m
                                                       aerodynamic
                                                       diameter.
------------------------------------------------------------------------


                        Table 2--Particle Sizes and Nominal Gas Velocities for Efficiency
----------------------------------------------------------------------------------------------------------------
                                                                       Target gas velocities (m/sec)
               Particle size (m)a               -------------------------------------------------------
                                                          71.0  151.5  252.5
----------------------------------------------------------------------------------------------------------------
50.5........................................  ................  .................  .................
70.5........................................  ................  .................  .................
100.5.......................................  ................  .................  .................
141.0.......................................  ................  .................  .................
201.0.......................................  ................  .................  .................
----------------------------------------------------------------------------------------------------------------
(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

[[Page 312]]

 
    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
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 Emissions (Constant 
                        Sampling Rate 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 (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 201. 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 emissions may be measured by an impinger analysis in 
combination with this method.
    1.2 Principle. A gas sample is extracted at a constant flow rate 
through an in-stack sizing device, which separates PM greater than 
PM10. Variations from isokinetic sampling conditions are 
maintained within well-defined limits. The particulate mass is 
determined gravimetrically after removal of uncombined water.

                              2. Apparatus

    Note: Methods cited in this method are part of 40 CFR part 60, 
appendix A.
    2.1 Sampling Train. A schematic of the Method 201A sampling train is 
shown in Figure 1 of this method. With the exception of the PM10 
sizing device and in-stack filter, this train is the same as an EPA 
Method 17 train.
    2.1.1 Nozzle. Stainless steel (316 or equivalent) with a sharp 
tapered leading edge. Eleven nozzles that meet the design specification 
in Figure 2 of this method are recommended. A larger number of nozzles 
with small nozzle increments increase the likelihood that a single 
nozzle can be used for the entire traverse. If the nozzles do not meet 
the design specifications in Figure 2 of this method, then the nozzles 
must meet the criteria in Section 5.2 of this method.
    2.1.2 PM10 Sizer. Stainless steel (316 or equivalent), 
capable of determining the PM10 fraction. The sizing device 
shall be either a cyclone that meets the specifications in Section 5.2 
of this method or a cascade impactor that has been calibrated using the 
procedure in Section 5.4 of this method.
    2.1.3 Filter Holder. 63-mm, 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.

[[Page 313]]

    2.1.4 Pitot Tube. Same as in Method 5, Section 2.1.3. The pitot 
lines shall be made of heat resistant tubing and attached to the probe 
with stainless steel fittings.
    2.1.5 Probe Liner. Optional, same as in Method 5, Section 2.1.2.
    2.1.6 Differential Pressure Gauge, Condenser, Metering System, 
Barometer, and Gas Density Determination Equipment. Same as in Method 5, 
Sections 2.1.4, and 2.1.7 through 2.1.10, respectively.
    2.2 Sample Recovery.
    2.2.1 Nozzle, Sizing Device, Probe, and Filter Holder Brushes. Nylon 
bristle brushes with stainless steel wire shafts and handles, properly 
sized and shaped for cleaning the nozzle, sizing device, probe or probe 
liner, and filter holders.
    2.2.2 Wash Bottles, Glass Sample Storage Containers, Petri Dishes, 
Graduated Cylinder and Balance, Plastic Storage Containers, Funnel and 
Rubber Policeman, and Funnel. Same as in Method 5, Sections 2.2.2 
through 2.2.8, respectively.
    2.3 Analysis. Same as in Method 5, Section 2.3.

                               3. Reagents

    The reagents for 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 in Method 5, Section 
4.1.2, except use the directions on nozzle size selection and sampling 
time in this method. Use of any nozzle greater than 0.16 in. in diameter 
requires a sampling port diameter of 6 inches. Also, the required 
maximum number of traverse points at any location shall be 12.
    4.1.2.1 The sizing device must be in-stack or maintained at stack 
temperature during sampling. The blockage effect of the CSR 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. 
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 CSR sampling assembly such that 
flow disturbances are minimized.
    4.1.2.2 The setup calculations can be performed by using the 
following procedures.
    4.1.2.2.1 In order to maintain a cut size of 10 m in the 
sizing device, the flow rate through the sizing device must be 
maintained at a constant, discrete value during the run. If the sizing 
device is a cyclone that meets the design specifications in Figure 3 of 
this method, use the equations in Figure 4 of this method to calculate 
three orifice heads (H): one at the average stack temperature, 
and the other two at temperatures 28  deg.C (50 
deg.F) of the average stack temperature. Use H calculated at 
the average stack temperature as the pressure head for the sample flow 
rate as long as the stack temperature during the run is within 28  deg.C 
(50  deg.F) of the average stack temperature. If the stack temperature 
varies by more than 28  deg.C (50  deg.F), then use the appropriate 
H.
    4.1.2.2.2 If the sizing device is a cyclone that does not meet the 
design specifications in Figure 3 of this method, use the equations in 
Figure 4 of this method, except use the procedures in Section 5.3 of 
this method to determine Qs, the correct cyclone flow rate 
for a 10 m size.
    4.1.2.2.3 To select a nozzle, use the equations in Figure 5 of this 
method to calculate pmin and 
pmax for each nozzle at all three temperatures. If 
the sizing device is a cyclone that does not meet the design 
specifications in Figure 3 of this method, the example worksheets can be 
used.
    4.1.2.2.4 Correct the Method 2 pitot readings to Method 201A pitot 
readings by multiplying the Method 2 pitot readings by the square of a 
ratio of the Method 201A pitot coefficient to the Method 2 pitot 
coefficient. Select the nozzle for which pmin and 
pmax bracket all of the corrected Method 2 pitot 
readings. If more than one nozzle meets this requirement, select the 
nozzle giving the greatest symmetry. Note that if the expected pitot 
reading for one or more points is near a limit for a chosen nozzle, it 
may be outside the limits at the time of the run.
    4.1.2.2.5 Vary the dwell time, or sampling time, at each traverse 
point proportionately with the point velocity. Use the equations in 
Figure 6 of this method to calculate the dwell time at the first point 
and at each subsequent point. It is recommended that the number of 
minutes sampled at each point be rounded to the nearest 15 seconds.
    4.1.3 Preparation of Collection Train. Same as in Method 5, Section 
4.1.3, except omit directions about a glass cyclone.
    4.1.4 Leak-Check Procedure. The sizing device is removed before the 
post-test leak-check to prevent any disturbance of the collected sample 
prior to analysis.
    4.1.4.1 Pretest Leak-Check. A pretest leak-check of the entire 
sampling train, including the sizing device, is required. Use the leak-
check procedure in Method 5, Section 4.1.4.1 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.

[[Page 314]]

    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 procedure in Method 5, 
Section 4.1.4.3 to conduct a post-test leak-check.
    4.1.5 Method 201A Train Operation. Same as in Method 5, Section 
4.1.5, except use the procedures in this section for isokinetic sampling 
and flow rate adjustment. Maintain the flow rate calculated in Section 
4.1.2.2.1 of this method throughout the run provided the stack 
temperature is within 28  deg.C (50  deg.F) of the temperature used to 
calculate H. If stack temperatures vary by more than 28  deg.C 
(50  deg.F), use the appropriate H value calculated in Section 
4.1.2.2.1 of this method. Calculate the dwell time at each traverse 
point as in Figure 6 of this method.
    4.2 Sample Recovery. If a cascade impactor is used, use the 
manufacturer's recommended procedures for sample recovery. If a cyclone 
is used, use the same sample recovery as that in Method 5, Section 4.2, 
except an increased number of sample recovery containers is required.
    4.2.1 Container Number 1 (In-Stack Filter). The recovery shall be 
the same as that for Container Number 1 in Method 5, Section 4.2.
    4.2.3 Container Number 2 (Cyclone or Large PM Catch). This step is 
optional. The anisokinetic error for the cyclone PM is theoretically 
larger than the error for the PM10 catch. Therefore, adding 
all the fractions to get a total PM catch is not as accurate as Method 5 
or Method 201. Disassemble the cyclone and remove the nozzle to recover 
the large PM catch. Quantitatively recover the PM from the interior 
surfaces of the nozzle and 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.
    4.2.4 Container Number 3 (PM10). Quantitatively recover 
the PM from all of the surfaces from the cyclone exit to the front half 
of the in-stack filter holder, including the ``turn around'' cup inside 
the cyclone 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.
    4.2.6 Container Number 4 (Silica Gel). The recovery shall be the 
same as that for Container Number 3 in Method 5, Section 4.2.
    4.2.7 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 Method 
201A Container Number 1 like Container Number 1, Method 201A Container 
Numbers 2 and 3 like Container Number 2, and Method 201A Container 
Number 4 like Container Number 3. Use Figure 7 of this method to record 
the weights of PM collected. Use Figure 5-3 in Method 5, Section 4.3, to 
record the volume of water 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 procedures in section 6 to calculate PM10 
emissions and the criteria in section 6.3.5 to determine the 
acceptability of the results.

                             5. Calibration

    Maintain an accurate laboratory log of all calibrations.
    5.1 Probe Nozzle, Pitot Tube, Metering System, Probe Heater 
Calibration, Temperature Gauges, Leak-check of Metering System, and 
Barometer. Same as in Method 5, Section 5.1 through 5.7, respectively.
    5.2 Probe Cyclone and Nozzle Combinations. The probe cyclone and 
nozzle combinations need not be calibrated if both meet design 
specifications in Figures 2 and 3 of this method. If the nozzles do not 
meet design specifications, then test the cyclone and nozzle 
combinations for conformity with performance specifications (PS's) in 
Table 1 of this method. If the cyclone does not meet design 
specifications, then the cylcone and nozzle combination shall conform to 
the PS's and calibrate the cyclone to determine the relationship between 
flow rate, gas viscosity, and gas density. Use the procedures in Section 
5.2 of this method to conduct PS tests and the procedures in Section 5.3 
of this method to calibrate the cyclone. The purpose of the PS tests are 
to conform that the cyclone and nozzle combination has the desired 
sharpness of cut. Conduct the PS tests in a wind tunnel described in 
Section 5.2.1 of this method and particle generation system described in 
Section 5.2.2 of this method. Use five particle sizes and three wind 
velocities as listed in Table 2 of this method. A minimum of three 
replicate measurements of collection efficiency shall be performed for 
each of the 15 conditions listed, for a minimum of 45 measurements.
    5.2.1 Wind Tunnel. Perform the 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.
    5.2.2 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. 
Perform the particle size distribution verification 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.

[[Page 315]]

    5.2.2.1 Establish the size of the solid dye particles delivered to 
the test section of the wind tunnel by using the operating parameters of 
the particle generation system, and verify them 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, m, 
and 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.
    5.2.2.2 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 the purpose of this test. 
Multiplets are particles that are agglomerated, and satellites are 
particles that are smaller than the specified size range.
    5.2.3 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.
    5.2.4 Flow Measurements. Measure the cyclone air flow rates with a 
dry gas meter and a stopwatch, or a calibrated orifice system capable of 
measuring flow rates to within 2 percent.
    5.2.5 Performance Specification Procedure. Establish test particle 
generator operation and verify particle size microscopically. If 
monodisperity 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.
    5.2.5.1 The cyclone cut size, or D50, of a cyclone is 
defined here as the particle size having a 50 percent probability of 
penetration. Determine the cyclone flow rate at which D50 is 
10 m. A suggested procedure is to vary the cyclone flow rate 
while keeping a constant particle size of 10 m. Measure the PM 
collected in the cyclone (mc), the exit tube (mt), 
and the filter (mf). Calculate cyclone efficiency 
(Ec) for each flow rate as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.040

    5.2.5.2.  Do three replicates and calculate the average cyclone 
efficiency [Ec(avg)] as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.041

Where E1, E2, and E3 are replicate 
measurements of Ec.
    5.2.5.3  Calculate the standard deviation () for the 
replicate measurements of Ec as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.042

If  exceeds 0.10, repeat the replicated runs.
    5.2.5.4 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 the following procedure.
    5.2.5.5 Set the air velocity and particle size from one of the 
conditions in Table 2 of this method. Establish isokinetic sampling 
conditions and the correct flow rate in the cyclone (obtained by 
procedures in this section) such that the D50 is 10 
m. Sample long enough to obtain 5 percent precision 
on total collected mass as determined by the precision and the 
sensitivity of measuring technique. Determine separately the nozzle 
catch (mn), cyclone catch (mc), cyclone exit tube 
(Mt), and collection filter catch (mf) for each 
particle size and nominal gas velocity in Table 2 of this method. 
Calculate overall efficiency (Eo) as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.043

    5.2.5.6 Do three replicates for each combination of gas velocity and 
particle size in Table 2 of this method. Use the equation

[[Page 316]]

below to calculate the average overall efficiency [Eo(avg)] 
for each combination following the procedures described in this section 
for determining efficiency.
[GRAPHIC] [TIFF OMITTED] TC08NO91.044

Where E1, E2, and E3 are replicate 
measurements of Eo.

    5.2.5.7 Use the formula in Section 5.2.5.3 to calculate  
for the replicate measurements. If  exceeds 0.10 or if the 
particle sizes and nominal gas velocities are not within the limits 
specified in Table 2 of this method, repeat the replicate runs.
    5.2.6 Criteria for Acceptance. For each of the three gas stream 
velocities, plot the Eo(avg) as a function of particle size 
on Figure 8 of this method. Draw smooth curves through all particle 
sizes. Eo(avg) shall be within the banded region for all 
sizes, and the Ec(avg) shall be 500.5 percent at 
10 m.
    5.3 Cyclone Calibration Procedure. The purpose of this procedure is 
to develop the relationship between flow rate, gas viscosity, gas 
density, and D50.
    5.3.1 Calculate Cyclone Flow Rate. Determine flow rates and 
D50's for three different particle sizes between 5 m 
and 15 m, one of which shall be 10 m. All sizes must 
be determined within 0.5 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.
    5.3.1.1 On log-log graph paper, plot the Reynolds number (Re) on the 
abscissa, and the square root of the Stokes 50 number 
[(Stk50)12] on the ordinate for each temperature. 
Use the following equations to compute both values:
[GRAPHIC] [TIFF OMITTED] TC08NO91.045

[GRAPHIC] [TIFF OMITTED] TC08NO91.046

where:

Qcyc = Cyclone flow rate, cm3/sec.
 =  Gas density, g/cm3.
dcyc = Diameter of cyclone inlet, cm.
s =  Viscosity of stack gas, micropoise.
D50 = Aerodynamic diameter of a particle having a 50 percent 
probability of penetration, cm.

    5.3.1.2 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 m.
[GRAPHIC] [TIFF OMITTED] TC08NO91.047

where:

m = Slope of the calibration line.
b = y-intercept of the calibration line.
Qs = Cyclone flow rate for a cut size of 10 m, 
cm3/sec.
d = Diameter of nozzle, cm.
Ts = Stack gas temperature, R.
Ps = Absolute stack pressure, in. Hg.
Mw = Wet molecular weight of the stack gas, lb/1b-mole.
K1 = 4.077 x 10-3.

    5.3.1.3 Refer to the Method 201A operators manual, entitled 
Application Guide for Source PM10 Measurement with Constant 
Sampling Rate, for directions in the use of this equation for Q in the 
setup calculations.
    5.4 Cascade Impactor. The purpose of calibrating a cascade impactor 
is to determine the empirical constant (STK50), which is 
specific to the impactor and which permits the accurate determination of 
the cut size of the impactor stages at field conditions. It is not 
necessary to calibrate each individual impactor. Once an impactor has 
been calibrated, the calibration data can be applied to other impactors 
of identical design.
    5.4.1 Wind Tunnel. Same as in Section 5.2.1 of this method.
    5.4.2 Particle Generation System. Same as in Section 5.2.2 of this 
method.
    5.4.3 Hardware Configuration for Calibrations. An impaction stage 
constrains an aerosol to form circular or rectangular jets, which are 
directed toward a suitable substrate where the larger aerosol particles 
are collected. For calibration purposes, three stages of the cascade 
impactor shall be discussed and designated calibration stages 1, 2, and 
3. The first calibration stage consists of the collection substrate of 
an impaction stage and all upstream surfaces up to and including the 
nozzle. This may include other preceding impactor stages. The second and

[[Page 317]]

third calibration stages consist of each respective collection substrate 
and all upstream surfaces up to but excluding the collection substrate 
of the preceding calibration stage. This may include intervening 
impactor stages which are not designated as calibration stages. The cut 
size, or D50, of the adjacent calibration stages shall differ 
by a factor of not less than 1.5 and not more than 2.0. For example, if 
the first calibration stage has a D50 of 12 m, then 
the D50 of the downstream stage shall be between 6 and 8 
m.
    5.4.3.1 It is expected, but not necessary, that the complete 
hardware assembly will be used in each of the sampling runs of the 
calibration and performance determinations. Only the first calibration 
stage must be tested under isokinetic sampling conditions. The second 
and third calibration stages must be calibrated with the collection 
substrate of the preceding calibration stage in place, so that gas flow 
patterns existing in field operation will be simulated.
    5.4.3.2 Each of the PM10 stages should be calibrated with 
the type of collection substrate, viscid material (such as grease) or 
glass fiber, used in PM10 measurements. Note that most 
materials used as substrates at elevated temperatures are not viscid at 
normal laboratory conditions. The substrate material used for 
calibrations should minimize particle bounce, yet be viscous enough to 
withstand erosion or deformation by the impactor jets and not interfere 
with the procedure for measuring the collected PM.
    5.4.4 Calibration Procedure. Establish test particle generator 
operation and verify particle size microscopically. If monodispersity is 
to be verified by measurements at the beginning and the end of the run 
rather than by an integrated sample, these measurements shall be made at 
this time. Measure in triplicate the PM collected by the calibration 
stage (m) and the PM on all surfaces downstream of the respective 
calibration stage (m') for all of the flow rates and particle size 
combinations shown in Table 2 of this method. Techniques of mass 
measurement may include the use of a dye and spectrophotometer. 
Particles on the upstream side of a jet plate shall be included with the 
substrate downstream, except agglomerates of particles, which shall be 
included with the preceding or upstream substrate. Use the following 
formula to calculate the collection efficiency (E) for each stage.
    5.4.4.1 Use the formula in Section 5.2.5.3 of this method to 
calculate the standard deviation () for the replicate 
measurements. If  exceeds 0.10, repeat the replicate runs.
    5.4.4.2 Use the following formula to calculate the average 
collection efficiency (Eavg) for each set of replicate 
measurements.

    Eavg=(E1+E2+E3)/3

where E1, E2, and E3 are replicate 
measurements of E.

    5.4.4.3 Use the following formula to calculate Stk for each 
Eavg.
[GRAPHIC] [TIFF OMITTED] TC08NO91.048

where:

D = Aerodynamic diameter of the test particle, cm (g/
cm3)1/2.
Q = Gas flow rate through the calibration stage at inlet conditions, 
cm3/sec.
 = Gas viscosity, micropoise.
A = Total cross-sectional area of the jets of the calibration stage, 
cm2.
dj = Diameter of one jet of the calibration stage, cm.

    5.4.4.4 Determine Stk50 for each calibration stage by 
plotting Eavg versus Stk on log-log paper. Stk50 
is the Stk number at 50 percent efficiency. Note that particle bounce 
can cause efficiency to decrease at high values of Stk. Thus, 50 percent 
efficiency can occur at multiple values of Stk. The calibration data 
should clearly indicate the value of Stk50 for minimum 
particle bounce. Impactor efficiency versus Stk with minimal particle 
bounce is characterized by a monotonically increasing function with 
constant or increasing slope with increasing Stk.
    5.4.4.5 The Stk50 of the first calibration stage can 
potentially decrease with decreasing nozzle size. Therefore, 
calibrations should be performed with enough nozzle sizes to provide a 
measured value within 25 percent of any nozzle size used in 
PM10 measurements.
    5.4.5 Criteria For Acceptance. Plot Eavg for the first 
calibration stage versus the square root of the ratio of Stk to 
Stk50 on Figure 9 of this method. Draw a smooth curve through 
all of the points. The curve shall be within the banded region.

                             6. Calculations

Calculations are as specified in Method 5, sections 6.3 through 6.7, and 
6.9 through 6.11, with the addition of the following:

6.1 Nomenclature.
Bws=Moisture fraction of stack, 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.K2 (3.24 x 10-5 micropoise/ 
deg.R2).
C4=Viscosity constant, 53.147 micropoise/fraction 
O2.
C5=Viscosity constant, 74.143 micropoise/fraction 
H2O.
D50=Diameter of particles having a 50 percent probability of 
penetration, m.

[[Page 318]]

fo=Stack gas fraction O2, by volume, dry basis.
K1=0.3858  deg.K/mm Hg (17.64  deg.R/in. Hg).
Mw=Wet molecular weight of stack gas, g/g-mole (lb/lb-mole).
Md=Dry molecular weight of stack gas, g/g-mole (1b/1b-mole).
Pbar=Barometric pressure at sampling site, mm Hg (in. Hg).
Ps=Absolute stack pressure, mm Hg (in. Hg).
Qs=Total cyclone flow rate at wet cyclone conditions, 
m3/min (ft3/min).
Qs(std)=Total cyclone flow rate at standard conditions, dscm/
min (dscf/min).
Tm=Average absolute temperature of dry meter,  deg.K 
( deg.R).
Ts=Average absolute stack gas temperature,  deg.K ( deg.R).
Vw(std)=Volume of water vapor in gas sample (standard 
conditions), scm (scf).
=Total sampling time, min.
s=Viscosity of stack gas, micropoise.

    6.2 Analysis of Cascade Impactor Data. Use the manufacturer's 
recommended procedures to analyze data from cascade impactors.
    6.3 Analysis of Cyclone Data. Use the following procedures to 
analyze data from a single stage cyclone.
    6.3.1 PM10 Weight. Determine the PM catch in the 
PM10 range from the sum of the weights obtained from 
Container Numbers 1 and 3 less the acetone blank.
    6.3.2 Total PM Weight (optional). Determine the PM catch for greater 
than PM10 from the weight obtained from Container Number 2 
less the acetone blank, and add it to the PM10 weight.
    6.3.3 PM10 Fraction. Determine the PM10 
fraction of the total particulate weight by dividing the PM10 
particulate weight by the total particulate weight.
    6.3.4 Aerodynamic Cut Size. Calculate the stack gas viscosity as 
follows:

    s=C1+C2Ts+C3
Ts2+C4f02-C5Bws

    6.3.4.1 The PM10 flow rate, at actual cyclone conditions, 
is calculated as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.049

    6.3.4.2 Calculate the molecular weight on a wet basis of the stack 
gas as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.050

    6.3.4.3 Calculate the actual D50 of the cyclone for the 
given conditions as follows:
[GRAPHIC] [TIFF OMITTED] TC08NO91.051

where 1=0.027754 for metric units (0.15625 for English units).

    6.3.5 Acceptable Results. The results are acceptable if two 
conditions are met. The first is that 9.0 m  
D50  11.0 m. The second is that no 
sampling points are outside pmin and 
pmax, or that 80 percent  I  
120 percent and no more than one sampling point is outside 
pmin and pmax. If D50 
is less than 9.0 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 Particle 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 
PM10 Emissions. Southern Research Institute for the 
Environmental Protection Agency. April 1989. NTIS PB 89 190375, EPA/600/
3-88-056.
    4. Application Guide for Source PM10 Measurement with 
Constant Sampling Rate, EPA/600/3-88-057.

[[Page 319]]




[[Page 320]]





[[Page 321]]




    Barometric pressure,
Pbar, in. Hg= ______
    Stack static pressure,
Pg, in. H2 O= ______
    Average stack temperature,
ts,  deg.F= ______
    Meter temperature, tm,  deg.F= ______
    Orifice H@, in. H2 O= ______
Gas analysis:

%CO2= ______
%O2= ______
%N2+%CO= ______
    Fraction moisture content,
Bws= ______
Molecular weight of stack gas, dry basis:
Md=0.44 (%CO2)+0.32 (%O2)+0.28 
(%N2+%CO)= ______ lb/lb mole
Molecular weight of stack gas, wet basis:
Mw=Md (1-Bws)+18 (Bws)= 
______ lb/lb mole
Absolute stack pressure:
[GRAPHIC] [TIFF OMITTED] TC08NO91.073

Viscosity of stack gas:
s=152.418+0.2552 ts+3.2355 x 10-
5 ts2+0.53147 (%02)-74.143 Bws= 
______ micropoise
Cyclone flow rate:

[[Page 322]]

[GRAPHIC] [TIFF OMITTED] TC08NO91.052

    Figure 4. Example worksheet 1, cyclone flow rate and H.

Orifice pressure head (H) needed for cyclone flow rate:
[GRAPHIC] [TIFF OMITTED] TC08NO91.053

Calculate  H for three temperatures:

------------------------------------------------------------------------
     ts,  deg.F
------------------------------------------------------------------------
H, in. H2O
 
------------------------------------------------------------------------

    Stack viscosity, s,
micropoise = ______
    Absolute stack pressure,
Ps, in. Hg = ______
    Average stack temperature,
ts,  deg.F = ______
    Meter temperature, tm,  deg.F = ______
    Method 201A pitot coefficient,
Cp = ______
    Cyclone flow rate, ft3/min,
Qs = ______
    Method 2 pitot coefficient,
Cp' = ______
    Molecular weight of stack gas, wet basis,
Mw = ______
    Nozzle diameter, Dn, in. = ______

Nozzle velocity:
[GRAPHIC] [TIFF OMITTED] TC08NO91.054

[GRAPHIC] [TIFF OMITTED] TC08NO91.055

[GRAPHIC] [TIFF OMITTED] TC08NO91.056

    Maximum and minimum velocities:
    Calculate Rmin
    [GRAPHIC] [TIFF OMITTED] TC08NO91.057
    
    If Rmin is less than 0.5, or if an imaginary number 
occurs when calculating Rmin, use Equation 1 to calculate 
vmin. Otherwise, use Equation 2.
    Eq. 1 vmin = vn (0.5) = ____ ft/sec

[[Page 323]]

    Eq. 2 vmin =vn Rmin = ____ ft/sec
    Calculate Rmax.
    [GRAPHIC] [TIFF OMITTED] TC08NO91.058
    
    If Rmax is greater than 1.5, use Equation 3 to calculate 
vmax. Otherwise, use Equation 4.
    Eq. 3 vmax = vn (1.5) = ____ ft/sec
    Eq. 4 vmax =vn Rmax = ____ ft/sec

Maximum and minimum velocity head values:
[GRAPHIC] [TIFF OMITTED] TC08NO91.059

[GRAPHIC] [TIFF OMITTED] TC08NO91.060


------------------------------------------------------------------------
                     Nozzle No.
------------------------------------------------------------------------
Dn, in..............................................  ...  ...  ...  ...
vn, ft/sec..........................................  ...  ...  ...  ...
vmin, ft/sec........................................  ...  ...  ...  ...
vmax, ft/sec........................................  ...  ...  ...  ...
pmin, in. H2O..............................  ...  ...  ...  ...
pmax, in. H2O..............................  ...  ...  ...  ...
------------------------------------------------------------------------

Velocity traverse data:
[GRAPHIC] [TIFF OMITTED] TC08NO91.061

  Total run time, minutes = ______
Number of traverse points =
[GRAPHIC] [TIFF OMITTED] TC08NO91.062

where:

t1 = dwell time at first traverse point, minutes.
p'1 = the velocity head at the first traverse point 
(from a previous traverse), in. H20.
p'avg = the square of the average square root of the 
p's (from a previous velocity traverse), in. H20.

At subsequent traverse points, measure the velocity p and 
calculate the dwell time by using the following equation:

[[Page 324]]

[GRAPHIC] [TIFF OMITTED] TC08NO91.063

where:

tn = dwell time at traverse point n, minutes.
pn = measured velocity head at point n, in. 
H20.
p1 = measured velocity head at point 1 in. 
H20.


----------------------------------------------------------------------------------------------------------------
                          Port
   Point No.   -------------------------------------------------------------------------------------------------
                  p       t       p       t      p       t      p       t
----------------------------------------------------------------------------------------------------------------
1.............  .............  .........  ............  ........  ............  ........  ............  ........
2.............  .............  .........  ............  ........  ............  ........  ............  ........
3.............  .............  .........  ............  ........  ............  ........  ............  ........
4.............  .............  .........  ............  ........  ............  ........  ............  ........
5.............  .............  .........  ............  ........  ............  ........  ............  ........
6.............  .............  .........  ............  ........  ............  ........  ............  ........
----------------------------------------------------------------------------------------------------------------

    Plant ______
    Date ______
    Run no. ______
    Filter no. ______
    Amount of liquid lost during
transport ______
    Acetone blank volume, ml ______
    Acetone wash volume, ml (4) ______
(5) ______
    Acetone blank conc., mg/mg (Equation 5-4,
Method 5) ______
    Acetone wash blank, mg (Equation 5-5,
Method 5) ______

------------------------------------------------------------------------
                                                 Weight of PM10 (mg)
                                           -----------------------------
               Container No.                  Final     Tare     Weight
                                             weight    weight     gain
------------------------------------------------------------------------
1.........................................  ........  ........  ........
3.........................................  ........  ........  ........
                                                               ---------
    Total.................................  ........  ........  ........
                                                               ---------
    Less acetone blank....................  ........  ........  ........
                                                               ---------
    Weight of PM10........................  ........  ........  ........
------------------------------------------------------------------------



 Table 1--Performance Specifications for Source PM10 Cyclones and Nozzle
                              Combinations
------------------------------------------------------------------------
            Parameter                    Units          Specifications
------------------------------------------------------------------------
1. Collection efficiency.........  Percent.........  Such that
                                                      collection
                                                      efficiency falls
                                                      within envelope
                                                      specified by
                                                      Section 5.2.6 and
                                                      Figure 8.
2. Cyclone cut size (D50)........  m......  101
                                                      m
                                                      aerodynamic
                                                      diameter.
------------------------------------------------------------------------


                        Table 2--Particle Sizes and Nominal Gas Velocities for Efficiency
----------------------------------------------------------------------------------------------------------------
                                                                       Target gas velocities (m/sec)
               Particle size (m)a               -------------------------------------------------------
                                                          71.0  151.5  252.5
----------------------------------------------------------------------------------------------------------------
50.5........................................  ................  .................  .................
70.5........................................  ................  .................  .................
100.5.......................................  ................  .................  .................
141.0.......................................  ................  .................  .................
201.0.......................................  ................  .................  .................
----------------------------------------------------------------------------------------------------------------

(a) Mass median aerodynamic diameter.

[[Page 325]]




[[Page 326]]




  Method 202--Determination of Condensible Particulate Emissions From 
                           Stationary Sources

                     1. Applicability and Principle

    1.1 Applicability.
    1.1.1 This method applies to the determination of condensible 
particulate matter (CPM) emissions from stationary sources. It is 
intended to represent condensible matter as material that condenses 
after passing through a filter and as measured by this method (Note: The 
filter catch can be analyzed according to the appropriate method).
    1.1.2 This method may be used in conjunction with Method 201 or 201A 
if the probes are glass-lined. Using Method 202 in conjunction with 
Method 201 or 201A, only the impinger train configuration and analysis 
is addressed by this method. The sample train operation and front end 
recovery and analysis shall be conducted according to Method 201 or 
201A.
    1.1.3 This method may also be modified to measure material that 
condenses at other temperatures by specifying the filter and probe 
temperature. A heated Method 5 out-of-stack filter may be used instead 
of the in-stack filter to determine condensible emissions at wet 
sources.
    1.2 Principle.
    1.2.1 The CPM is collected in the impinger portion of a Method 17 
(appendix A, 40 CFR part 60) type sampling train. The impinger contents 
are immediately purged after the run with nitrogen (N2) to 
remove dissolved sulfur dioxide (SO2) gases from the impinger 
contents. The impinger solution is then extracted with methylene 
chloride (MeCl2). The organic and aqueous fractions are then 
taken to dryness and the residues weighed. The total of both fractions 
represents the CPM.
    1.2.2 The potential for low collection efficiency exist at oil-fired 
boilers. To improve the collection efficiency at these type of sources, 
an additional filter placed between the second and third impinger is 
recommended.

[[Page 327]]

                      2. Precision and Interference

    2.1 Precision. The precision based on method development tests at an 
oil-fired boiler and a catalytic cracker were 11.7 and 4.8 percent, 
respectively.
    2.2 Interference. Ammonia. In sources that use ammonia injection as 
a control technique for hydrogen chloride (HC1), the ammonia interferes 
by reacting with HC1 in the gas stream to form ammonium chloride 
(NH4 C1) which would be measured as CPM. The sample may be 
analyzed for chloride and the equivalent amount of NH4 C1 can 
be subtracted from the CPM weight. However, if NH4 C1 is to 
be counted as CPM, the inorganic fraction should be taken to near 
dryness (less than 1 ml liquid) in the oven and then allowed to air dry 
at ambient temperature to prevent any NH4 C1 from vaporizing.

                              3. Apparatus

    3.1 Sampling Train. Same as in Method 17, section 2.1, with the 
following exceptions noted below (see Figure 202-1). Note: Mention of 
trade names or specific products does not constitute endorsement by EPA.
    3.1.1 The probe extension shall be glass-lined or Teflon.
    3.1.2 Both the first and second impingers shall be of the Greenburg-
Smith design with the standard tip.
    3.1.3 All sampling train glassware shall be cleaned prior to the 
test with soap and tap water, water, and rinsed using tap water, water, 
acetone, and finally, MeCl2. It is important to completely 
remove all silicone grease from areas that will be exposed to the 
MeCl2 during sample recovery.
    3.2 Sample Recovery. Same as in Method 17, section 2.2, with the 
following additions:
    3.2.1 N2 Purge Line. Inert tubing and fittings capable of 
delivering 0 to 28 liters/min of N2 gas to the impinger train 
from a standard gas cylinder (see Figure 202-2). Standard 0.95 cm (\3/
8\-inch) plastic tubing and compression fittings in conjunction with an 
adjustable pressure regulator and needle valve may be used.
    3.2.2 Rotameter. Capable of measuring gas flow at 20 liters/min.
    3.3 Analysis. The following equipment is necessary in addition to 
that listed in Method 17, section 2.3:
    3.3.1 Separatory Funnel. Glass, 1-liter.
    3.3.2 Weighing Tins. 350-ml.
    3.3.3 Dry Equipment. Hot plate and oven with temperature control.
    3.3.4 Pipets. 5-ml.
    3.3.5 Ion Chromatograph. Same as in Method 5F, Section 2.1.6.

                               4. Reagents

    Unless otherwise indicated, all reagents must conform to the 
specifications established by the Committee on Analytical Reagents of 
the American Chemical Society. Where such specifications are not 
available, use the best available grade.
    4.1 Sampling. Same as in Method 17, section 3.1, with the addition 
of deionized distilled water to conform to the American Society for 
Testing and Materials Specification D 1193-74, Type II and the omittance 
of section 3.1.4.
    4.2 Sample Recovery. Same as in Method 17, section 3.2, with the 
following additions:
    4.2.1 N2 Gas. Zero N2 gas at delivery 
pressures high enough to provide a flow of 20 liters/min for 1 hour 
through the sampling train.
    4.2.2 Methylene Chloride, ACS grade. Blanks shall be run prior to 
use and only methylene chloride with low blank values (0.001 percent) 
shall be used.
    4.2.3 Water. Same as in section 4.1.
    4.3 Analysis. Same as in Method 17, section 3.3, with the following 
additions:
    4.3.1 Methylene Chloride. Same as section 4.2.2.
    4.3.2 Ammonium Hydroxide. Concentrated (14.8 M) NH4 OH.
    4.3.3 Water. Same as in section 4.1.
    4.3.4 Phenolphthalein. The pH indicator solution, 0.05 percent in 50 
percent alcohol.

                              5. Procedure

    5.1 Sampling. Same as in Method 17, section 4.1, with the following 
exceptions:
    5.1.1 Place 100 ml of water in the first three impingers.
    5.1.2 The use of silicone grease in train assembly is not 
recommended because it is very soluble in MeCl2 which may 
result in sample contamination. Teflon tape or similar means may be used 
to provide leak-free connections between glassware.
    5.2 Sample Recovery. Same as in Method 17, section 4.2 with the 
addition of a post-test N2 purge and specific changes in 
handling of individual samples as described below.
    5.2.1 Post-test N2 Purge for Sources Emitting SO2. 
(Note: This step is recommended, but is optional. With little or no 
SO2 is present in the gas stream, i.e., the pH of the 
impinger solution is greater than 4.5, purging has been found to be 
unnecessary.) As soon as possible after the post-test leak check, detach 
the probe and filter from the impinger train. Leave the ice in the 
impinger box to prevent removal of moisture during the purge. If 
necessary, add more ice during the purge to maintain the gas temperature 
below 20  deg.C. With no flow of gas through the clean purge line and 
fittings, attach it to the input of the impinger train (see Figure 202-
2). To avoid over- or under-pressurizing the impinger array, slowly 
commence the N2 gas flow through the line while 
simultaneously opening the meter box pump valve(s). When using the gas 
cylinder pressure to push the purge gas through the sample train, adjust 
the flow rate to 20 liters/min through the rotameter. When pulling the

[[Page 328]]

purge gas through the sample train using the meter box vacuum pump, set 
the orifice pressure differential to H@ and maintain 
an overflow rate through the rotameter of less than 2 liters/min. This 
will guarantee that the N2 delivery system is operating at 
greater than ambient pressure and prevents the possibility of passing 
ambient air (rather than N2) through the impingers. Continue 
the purge under these conditions for 1 hour, checking the rotameter and 
H value(s) periodically. After 1 hour, simultaneously turn off 
the delivery and pumping systems.
    5.2.2 Sample Handling.
    5.2.2.1 Container Nos. 1, 2, and 3. If filter catch is to be 
determined, as detailed in Method 17, section 4.2.
    5.2.2.2 Container No. 4 (Impinger Contents). Measure the liquid in 
the first three 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 or weight of liquid present to be used to calculate the moisture 
content of the effluent gas. Quantitatively transfer this liquid into a 
clean sample bottle (glass or plastic); rinse each impinger and the 
connecting glassware, including probe extension, twice with water, 
recover the rinse water, and add it to the same sample bottle. Mark the 
liquid level on the bottle.
    5.2.2.3 Container No. 5 (MeCl2 Rinse). Follow the water 
rinses of each impinger and the connecting glassware, including the 
probe extension with two rinses of MeCl2; save the rinse 
products in a clean, glass sample jar. Mark the liquid level on the jar.
    5.2.2.4 Container No. 6 (Water Blank). Once during each field test, 
place 500 ml of water in a separate sample container.
    5.2.2.5 Container No. 7 (MeCl2 Blank). Once during each 
field test, place in a separate glass sample jar a volume of MeCl2 
approximately equivalent to the volume used to conduct the MeCl2 
rinse of the impingers.
    5.3 Analysis. Record the data required on a sheet such as the one 
shown in Figure 202-3. Handle each sample container as follows:
    5.3.1 Container Nos. 1, 2, and 3. If filter catch is analyzed, as 
detailed in Method 17, section 4.3.
    5.3.2 Container Nos. 4 and 5. Note the level of liquid in the 
containers and confirm on the 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 No. 4 either volumetrically to plus-minus1 ml or 
gravimetrically to plus-minus0.5 g. Remove a 5-ml aliquot and 
set aside for later ion chromatographic (IC) analysis of sulfates. 
(Note: Do not use this aliquot to determine chlorides since the HCl will 
be evaporated during the first drying step; Section 8.2 details a 
procedure for this analysis.)
    5.3.2.1 Extraction. Separate the organic fraction of the sample by 
adding the contents of Container No. 4 (MeCl2) to the 
contents of Container No. 4 in a 1000-ml separatory funnel. After 
mixing, allow the aqueous and organic phases to fully separate, and 
drain off most of the organic/MeCl2 phase. Then add 75 ml of 
MeCl2 to the funnel, mix well, and drain off the lower 
organic phase. Repeat with another 75 ml of MeCl2. This 
extraction should yield about 250 ml of organic extract. Each time, 
leave a small amount of the organic/MeCl2 phase in the 
separatory funnel ensuring that no water is collected in the organic 
phase. Place the organic extract in a tared 350-ml weighing tin.
    5.3.2.2 Organic Fraction Weight Determination (Organic Phase from 
Container Nos. 4 and 5). Evaporate the organic extract at room 
temperature and pressure in a laboratory hood. Following evaporation, 
desiccate the organic fraction 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.
    5.3.2.3 Inorganic Fraction Weight Determination. (Note: If NH4 
Cl is to be counted as CPM, the inorganic fraction should be taken to 
near dryness (less than 1 ml liquid) in the oven and then allow to air 
dry at ambient temperature. If multiple acid emissions are suspected, 
the ammonia titration procedure in section 8.1 may be preferred.) Using 
a hot plate, or equivalent, evaporate the aqueous phase to approximately 
50 ml; then, evaporate to dryness in a 105  deg.C oven. Redissovle the 
residue in 100 ml of water. Add five drops of phenolphthalein to this 
solution; then, add concentrated (14.8 M) NH4 OH until the 
sample turns pink. Any excess NH2 OH will be evaporated 
during the drying step. Evaporate the sample to dryness in a 105  deg.C 
oven, desiccate the sample for 24 hours, weigh to a constant weight, and 
record the results to the nearest 0.1 mg. (Note: The addition of 
NH4 OH is recommended, but is optional when little or no 
SO2 is present in the gas stream, i.e., when the pH of the 
impinger solution is greater than 4.5, the addition of NH4 OH 
is not necessary.)
    5.3.2.4 Analysis of Sulfate by IC to Determine Ammonium Ion 
(NH4+) Retained in the Sample. (Note: If NH4 OH is 
not added, omit this step.) Determine the amount of sulfate in the 
aliquot taken from Container No. 4 earlier as described in Method 5F 
(appendix A, 40 CFR part 60). Based on the IC SO4-2 analysis 
of the aliquot, calculate the correction factor to subtract the 
NH4+ retained in the sample and to add the combined water 
removed by the acid-base reaction (see section 7.2).
    5.3.3 Analysis of Water and MeCl2 Blanks (Container Nos. 
6 and 7). Analyze these sample blanks as described above in sections 
5.3.2.3 and 5.3.2.2, respectively.

[[Page 329]]

    5.3.4 Analysis of Acetone Blank (Container No. 8). Same as in Method 
17, section 4.3.

                             6. Calibration

    Same as in Method 17, section 5, except for the following:
    6.1 IC Calibration. Same as Method 5F, section 5.
    6.2 Audit Procedure. Concurrently, analyze the audit sample and a 
set of compliance samples in the same manner to evaluate the technique 
of the analyst and the standards preparation. The same analyst, 
analytical reagents, and analytical system shall be used both for 
compliance samples and the EPA audit sample. If this condition is met, 
auditing of subsequent compliance analyses for the same enforcement 
agency within 30 days is not required. An audit sample set may not be 
used to validate different sets of compliance samples under the 
jurisdiction of different enforcement agencies, unless prior 
arrangements are made with both enforcement agencies.
    6.3 Audit Samples. Audit Sample Availability. Audit samples will be 
supplied only to enforcement agencies for compliance tests. The 
availability of audit samples may be obtained by writing:

Source Test Audit Coordinator (MD-77B), Quality Assurance Division, 
Atmospheric Research and Exposure Assessment Laboratory, U.S. 
Environmental Protection Agency, Research Triangle, Park, NC 27711

or by calling the Source Test Audit Coordinator (STAC) at (919) 541-
7834. The request for the audit sample must be made at least 30 days 
prior to the scheduled compliance sample analysis.
    6.4 Audit Results. Calculate the audit sample concentration 
according to the calculation procedure described in the audit 
instructions included with the audit sample. Fill in the audit sample 
concentration and the analyst's name on the audit response form included 
with the audit instructions. Send one copy to the EPA Regional Office or 
the appropriate enforcement agency and a second copy to the STAC. The 
EPA Regional Office or the appropriate enforcement agency will report 
the results of the audit to the laboratory being audited. Include this 
response with the results of the compliance samples in relevant reports 
to the EPA Regional Office or the appropriate enforcement agency.

                             7. Calculations

    Same as in Method 17, section 6, with the following additions:
    7.1 Nomenclature. Same as in Method 17, section 6.1 with the 
following additions.

Ccpm=Concentration of the CPM in the stack gas, dry basis, 
corrected to standard conditions, g/dscm (g/dscf).
CSO4=Concentration of SO4-2 in the sample, mg/ml.
mb=Sum of the mass of the water and MeCl2 blanks, 
mg.
mc=Mass of the NH4+ added to sample to form 
ammonium sulfate, mg.
mi=Mass of inorganic CPM matter, mg.
mo=Mass of organic CPM, mg.
mr=Mass of dried sample from inorganic fraction, mg.
Vb=Volume of aliquot taken for IC analysis, ml.
Vic=Volume of impinger contents sample, ml.

    7.2 Correction for NH4+ and H2O. Calculate the 
correction factor to subtract the NH4+ retained in the sample 
based on the IC SO4-2 and if desired, add the combined water 
removed by the acid-base reaction.
[GRAPHIC] [TIFF OMITTED] TC08NO91.064

  =0.1840, when only correcting for NH4+.

    7.3  Mass of Inorganic CPM.
    [GRAPHIC] [TIFF OMITTED] TC08NO91.065
    
7.4
    Concentration of CPM.
    [GRAPHIC] [TIFF OMITTED] TC08NO91.066
    
                        8. Alternative Procedures

    8.1 Determination of NH4+ Retained in Sample by 
Titration.
    8.1.1 An alternative procedure to determine the amount of 
NH4+ added to the inorganic fraction by titration may be 
used. After dissolving the inorganic residue in 100 ml of water, titrate 
the solution with 0.1 N NH4 OH to a pH of 7.0, as indicated 
by a pH meter. The 0.1 N NH4 OH is made as follows: Add 7 ml 
of concentrated (14.8 M) NH4 OH to 1 liter of water. 
Standardize against standardized 0.1 N H2 SO4 and 
calculate the exact normality using a procedure parallel to that 
described in section 5.5 of Method 6 (appendix A, 40 CFR part 60). 
Alternatively, purchase 0.1 N NH4 OH that has been 
standardized against a National Institute of Standards and Technology 
reference material.
    8.1.2 Calculate the concentration of SO4-2 in the sample 
using the following equation.
[GRAPHIC] [TIFF OMITTED] TC08NO91.067

where

N = Normality of the NH4OH, mg/ml.
Vt = Volume of NH4 OH titrant, ml.
48.03 = mg/meq.
100 = Volume of solution, ml.


[[Page 330]]


    8.3.1 Calculate the CPM as described in section 7.
    8.2 Analysis of Chlorides by IC. At the conclusion of the final 
weighing as described in section 5.3.2.3, redissolve the inorganic 
fraction in 100 ml of water. Analyze an aliquot of the redissolved 
sample for chlorides by IC using techniques similar to those described 
in Method 5F for sulfates. Previous drying of the sample should have 
removed all HCl. Therefore, the remaining chlorides measured by IC can 
be assumed to be NH4 Cl, and this weight can be subtracted 
from the weight determined for CPM.
    8.3 Air Purge to Remove SO2 from Impinger Contents. As an 
alternative to the post-test N2 purge described in section 
5.2.1, the tester may opt to conduct the post-test purge with air at 20 
liter/min. Note: The use of an air purge is not as effective as a 
N2 purge.
    8.4 Chloroform-ether Extraction. As an alternative to the methylene 
chloride extraction described in section 5.3.2.1, the tester may opt to 
conduct a chloroform-ether extraction. Note: The Chloroform-ether was 
not as effective as the MeCl2 in removing the organics, but 
it was found to be an acceptable organic extractant. Chloroform and 
diethylether of ACS grade, with low blank values (0.001 percent), shall 
be used. Analysis of the chloroform and diethylether blanks shall be 
conducted according to Section 5.3.3 for MeCl2.
    8.4.1 Add the contents of Container No. 4 to a 1000-ml separatory 
funnel. Then add 75 ml of chloroform to the funnel, mix well, and drain 
off the lower organic phase. Repeat two more times with 75 ml of 
chloroform. Then perform three extractions with 75 ml of diethylether. 
This extraction should yield approximately 450 ml of organic extraction. 
Each time, leave a small amount of the organic/MeCl2 phase in 
the separatory funnel ensuring that no water is collected in the organic 
phase.
    8.4.2 Add the contents of Container No. 5 to the organic extraction. 
Place approximately 300 ml of the organic extract in a tared 350-ml 
weighing tin while storing the remaining organic extract in a sample 
container. As the organic extract evaporates, add the remaining extract 
to the weighing tin.
    8.4.3 Determine the weight of the organic phase as described in 
Section 5.3.2.2.
    8.5 Improving Collection Efficiency. If low impinger collection 
efficiency is suspected, the following procedure may be used.
    8.5.1 Place an out-of-stock filter as described in Method 8 between 
the second and third impingers.
    8.5.2 Recover and analyze the filter according to Method 17, Section 
4.2. Include the filter holder as part of the connecting glassware and 
handle as described in sections 5.2.2.2 and 5.2.2.3.
    8.5.3 Calculate the Concentration of CPM as follows:
    [GRAPHIC] [TIFF OMITTED] TC08NO91.068
    
where:

mf = amount of CPM collected on out-of-stack filter, mg.

    8.6 Wet Source Testing. When testing at a wet source, use a heated 
out-of-stack filter as described in Method 5.

                             9. Bibliography

    1. DeWees, W.D., S.C. Steinsberger, G.M. Plummer, L.T. Lay, G.D. 
McAlister, and R.T. Shigehara. ``Laboratory and Field Evaluation of the 
EPA Method 5 Impinger Catch for Measuring Condensible 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.
    2. DeWees, W.D. and K.C. Steinsberger. ``Method Development and 
Evaluation of Draft Protocol for Measurement of Condensible Particulate 
Emissions.'' Draft Report. November 17, 1989.
    3. Texas Air Control Board, Laboratory Division. ``Determination of 
Particulate in Stack Gases Containing Sulfuric Acid and/or Sulfur 
Dioxide.'' Laboratory Methods for Determination of Air Pollutants. 
Modified December 3, 1976.
    4. Nothstein, Greg. Masters Thesis. University of Washington. 
Department of Environmental Health. Seattle, Washington.
    5. ``Particulate Source Test Procedures Adopted by Puget Sound Air 
Pollution Control Agency Board of Directors.'' Puget Sound Air Pollution 
Control Agency, Engineering Division. Seattle, Washington. August 11, 
1983.
    6. Commonwealth of Pennsylvania, Department of Environmental 
Resources. 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.
    7. Wisconsin Department of Natural Resources. Air Management 
Operations Handbook, Revision 3. January 11, 1988.

[[Page 331]]




[[Page 332]]




                         Moisture Determination

Volume or weight of liquid in impingers: ______ ml or g
Weight of moisture in silica gel: ______ g

                  Sample Preparation (Container No. 4)

Amount of liquid lost during transport: ______ ml
Final volume: ______ ml
pH of sample prior to analysis: ______

[[Page 333]]

Addition of NH4 OH required: ______
Sample extracted 2X with 75 ml MeCl2?: ______

                        For Titration of Sulfate

Normality of NH2 OH: ______ N
Volume of sample titrated: ______ ml
Volume of titrant: ______ ml

                             Sample Analysis

------------------------------------------------------------------------
                                                 Weight of condensible
                                                    particulate, mg
               Container number               --------------------------
                                                Final     Tare    Weight
                                                weight   weight    gain
------------------------------------------------------------------------
4 (Inorganic)................................  .......  .......  .......
4 & 5 (Organic)..............................  .......  .......  .......
------------------------------------------------------------------------

Total: ______
Less Blank: ______
Weight of Consensible Particulate:
Figure 202-3. Analytical data sheet.

 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


[[Page 334]]


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 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 10.05.
    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 335]]

[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 336]]

    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 1205  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 
1205  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 1005  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 337]]

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.
    7.2  Audits.
    7.2.1  Audit Procedure. Concurrently, analyze the audit sample and a 
set of compliance samples in the same manner to evaluate the technique 
of the analyst and the standards preparation. The same analyst, 
analytical reagents, and analytical system shall be used both for 
compliance samples and the EPA audit sample. If this condition is met, 
auditing of subsequent compliance analyses for the same enforcement 
agency within 30 days is not required. An audit sample set may not be 
used to validate different sets of compliance samples under the 
jurisdiction of different enforcement agencies, unless prior 
arrangements are made with both enforcement agencies.
    7.2.2  Audit Samples and Audit Sample Availability. Audit samples 
will be supplied only to enforcement agencies for compliance tests. The 
availability of audit samples may be obtained by writing: Source Test 
Audit Coordinator (STAC) (MD-77B), Quality Assurance Division, 
Atmospheric Research and

[[Page 338]]

Exposure Assessment Laboratory, U.S. Environmental Protection Agency, 
Research Triangle Park, NC 27711 or by calling the STAC at (919) 541-
7834. The request for the audit sample must be made at least 30 days 
prior to the scheduled compliance sample analysis.
    7.2.3  Audit Results. Calculate the audit sample concentration 
according to the calculation procedure described in the audit 
instructions included with the audit sample. Fill in the audit sample 
concentration and the analyst's name on the audit response form included 
with the audit instructions. Send one copy to the EPA Regional Office or 
the appropriate enforcement agency, and a second copy to the STAC. The 
EPA Regional Office or the appropriate enforcement agency will report 
the results of the audit to the laboratory being audited. Include this 
response with the results of the compliance samples in relevant reports 
to the EPA Regional Office or the appropriate enforcement agency.

                   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.
    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

[[Page 339]]

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 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.

[[Page 340]]

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.
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
    
    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 341]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.036


[[Page 342]]


[GRAPHIC] [TIFF OMITTED] TR16JN97.037


[[Page 343]]


[GRAPHIC] [TIFF OMITTED] TR16JN97.038


[[Page 344]]



  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 (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 345]]

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.
    6.2  Audits.
    6.2.1  Analysis Audit Procedure. Immediately before each test, 
analyze an audit cylinder as described in section 7.2. The analysis 
audit must agree with the audit cylinder concentration within 10 
percent.
    6.2.2  Audit Samples and Audit Sample Availability. Audit samples 
will be supplied only to enforcement agencies for compliance tests. The 
availability of audit samples may be obtained by writing: Source Test 
Audit Coordinator (STAC) (MD-77B), Quality Assurance Division, 
Atmospheric Research and Exposure Assessment Labortory, U.S. 
Environmental Protection Agency, Research Triangle Park, NC 27711 or by 
calling the STAC at (919) 541-7834. The request for the audit sample 
must be made at least 30 days prior to the scheduled compliance sample 
analysis.
    6.2.3  Audit Results. Calculate the audit sample concentration 
according to the calculation procedure described in the audit 
instructions included with the audit sample. Fill in the audit sample 
concentration and the analyst's name on the audit response form included 
with the audit instructions. Send one copy to the EPA Regional Office or 
the appropriate enforcement agency, and a second copy to the STAC. The 
EPA Regional Office or the appropriate enforcement agency will report 
the results of the audit to the laboratory being audited. Include this 
response with the results of the compliance samples in relevant reports 
to the EPA Regional Office or the appropriate enforcement agency.

                   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

[[Page 346]]

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.
    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 1205  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.

[[Page 347]]

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.
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
    
    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 348]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.027


[[Page 349]]


[GRAPHIC] [TIFF OMITTED] TR16JN97.028


[[Page 350]]



  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 (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 351]]

    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.
    6.2  Audits.
    6.2.1  Analysis Audit Procedure. Immediately before each test, 
analyze an audit cylinder as described in section 7.2. The analysis 
audit must agree with the audit cylinder concentration within 10 
percent.
    6.2.2  Audit Samples and Audit Sample Availability. Audit samples 
will be supplied only to enforcement agencies for compliance tests. The 
availability of audit samples may be obtained by writing: Source Test 
Audit Coordinator (STAC) (MD-77B), Quality Assurance Division, 
Atmospheric Research and Exposure Assessment Laboratory, U.S. 
Environmental Protection Agency, Research Triangle Park, NC 27711 or by 
calling the STAC at (919) 541-7834. The request for the audit sample 
must be made at least 30 days prior to the scheduled compliance sample 
analysis.
    6.2.3  Audit Results. Calculate the audit sample concentration 
according to the calculation procedure described in the audit 
instructions included with the audit sample. Fill in the audit sample 
concentration and the analyst's name on the audit response form included 
with the audit instructions. Send one copy to the EPA Regional Office or 
the appropriate enforcement agency, and a second copy to the STAC. The 
EPA Regional Office or the appropriate enforcement agency will report 
the results of the audit to the laboratory being audited. Include this 
response with the results of the compliance samples in relevant reports 
to the EPA Regional Office or the appropriate enforcement agency.

[[Page 352]]

                   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 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

[[Page 353]]

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, ft2.
AN=total area of all NDO's in the enclosure, ft2.
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/(m3-ppm).
n=number of measurement points.
QGj=average effluent volumetric flow rate corrected to 
standard conditions at captured emissions point j, m3/min.
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 354]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.029


[[Page 355]]


[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 356]]

    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 (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 357]]

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.
    6.2  Audits.
    6.2.1  Analysis Audit Procedure. Immediately before each test, 
analyze an audit cylinder as described in section 7.2. The analysis 
audit must agree with the audit cylinder concentration within 10 
percent.
    6.2.2  Audit Samples and Audit Sample Availability. Audit samples 
will be supplied only to enforcement agencies for compliance tests. The 
availability of audit samples may be obtained by writing: Source Test 
Audit Coordinator (STAC) (MD-77B) Quality Assurance Division, 
Atmospheric Research and Exposure Assessment Laboratory, U.S. 
Environmental Protection Agency, Research Triangle Park, NC 27711 or by 
calling the STAC at (919) 541-7834. The request for the audit sample 
must be made at least 30 days prior to the scheduled compliance sample 
analysis.
    6.2.3  Audit Results. Calculate the audit sample concentration 
according to the calculation procedure described in the audit 
instructions included with the audit sample. Fill in the audit sample 
concentration and the analyst's name on the audit response form included 
with the audit instructions. Send one copy to the EPA Regional Office or 
the appropriate enforcement agency, and a second copy to the STAC. The 
EPA Regional Office or the appropriate enforcement agency will report 
the results of the audit to the laboratory being audited. Include this 
response with the results of the compliance samples in relevant reports 
to the EPA Regional Office or the appropriate enforcement agency.

                   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

[[Page 358]]

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 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 1205  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.

[[Page 359]]

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.
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.
    [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 360]]

[GRAPHIC] [TIFF OMITTED] TR16JN97.031


[[Page 361]]


[GRAPHIC] [TIFF OMITTED] TR16JN97.032


[[Page 362]]



 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 
(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 363]]

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.
    6.2  Audits.
    6.2.1  Analysis Audit Procedure. Immediately before each test, 
analyze an audit cylinder as described in section 7.2. The analysis 
audit must agree with the audit cylinder concentration within 10 
percent.
    6.2.2  Audit Samples and Audit Sample Availability. Audit samples 
will be supplied only to enforcement agencies for compliance tests. The 
availability of audit samples may be obtained by writing: Source Test 
Audit Coordinator (STAC) (MD-77B), Quality Assurance Division, 
Atmospheric Research and Exposure Assessment Laboratory, U.S. 
Environmental Protection Agency, Research Triangle Park, NC 27711 or by 
calling the STAC at (919) 541-7834. The request for the audit sample 
must be made at least 30 days prior to the scheduled compliance sample 
analysis.
    6.2.3  Audit Results. Calculate the audit sample concentration 
according to the calculation procedure described in the audit 
instructions included with the audit sample. Fill in the audit sample 
concentration and the analyst's name on the audit response form included 
with the audit instructions. Send one copy to the EPA Regional Office or 
the appropriate enforcement agency, and a second copy to the STAC. The 
EPA Regional Office or the appropriate enforcement agency will report 
the results of the audit to the laboratory being audited. Include this 
response with the results of the compliance samples in relevant reports 
to the EPA Regional Office or the appropriate enforcement agency.

                   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

[[Page 364]]

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 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

[[Page 365]]

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.
F=total duration of CE sampling run, min.

    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 366]]

[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 367]]

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 an 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-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 368]]

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.
    6.3  Audits.
    6.3.1  Audit Procedure. Concurrently, analyze the audit sample and a 
set of compliance samples in the same manner to evaluate the technique 
of the analyst and the standards preparation. The same analyst, 
analytical reagents, and analytical system shall be used both for 
compliance samples and the EPA audit sample. If this condition is met, 
auditing of subsequent compliance analyses for the same enforcement 
agency within 30 days is not required. An audit sample set may not be 
used to validate different sets of compliance samples under the 
jurisdiction of different enforcement agencies, unless prior 
arrangements are made with both enforcement agencies.
    6.3.2  Audit Samples. Audit Sample Availability. Audit samples will 
be supplied only to enforcement agencies for compliance tests. The 
availability of audit samples may be obtained by writing: Source Test 
Audit Coordinator (STAC) (MD-77B), Quality Assurance Division, 
Atmospheric Research and Exposure Assessment Laboratory, U.S. 
Environmental Protection Agency, Research Triangle Park, NC 27711 or by 
calling the STAC at (919) 541-7834. The request for the audit sample 
must be made at least 30 days prior to the scheduled compliance sample 
analysis.
    6.3.3  Audit Results. Calculate the audit sample concentration 
according to the calculation procedure described in the audit 
instructions included with the audit sample. Fill in the audit sample 
concentration and the analyst's name on the audit response form included 
with the audit instructions. Send one copy to the EPA Regional Office or 
the appropriate enforcement agency, and a second copy to the STAC. The 
EPA Regional Office or the appropriate enforcement agency will report 
the results of the audit to the laboratory being audited. Include this 
response with the results of the compliance samples in relevant reports 
to the EPA Regional Office or the appropriate enforcement agency.

[[Page 369]]

                   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 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.

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    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. 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.

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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

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[GRAPHIC] [TIFF OMITTED] TR16JN97.034


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[GRAPHIC] [TIFF OMITTED] TR16JN97.035


[[Page 374]]



 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 primary flow standards with an 
uncertainty 0.25 percent. A label shall be affixed at all 
times to the gas dilution system listing the date of the most recent 
calibration, the due date for the next calibration, and the person or 
manufacturer who carried out the calibration. 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 recalibration documentation shall 
be made available for the Administrator's inspection upon request.
    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 the 
source owner or operator. It is recommended that the source owner or 
operator choose a precalibrated instrument with a

[[Page 375]]

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.

[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]

                        Appendixes N-O [Reserved]

     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 51.165(b). 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.

[[Page 376]]

    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:
    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.

[[Page 377]]

    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.
    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 2.1, Performance 
Specification 2, appendix B, part 60) 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 2.1, 
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 2.1, 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 six 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 
sulfur dioxide, 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

[[Page 378]]

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 (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 for each calendar quarter 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

[[Page 379]]

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 in the 
quarterly summaries, and 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 
paragraph 4.1.4 of this appendix,
F, Fc = a factor representing a ratio of the volume of dry 
flue gases generated to the calorific value of the fuel combusted (F), 
and a factor representing a ratio of the volume of carbon dioxide 
generated to the calorific value of the fuel combusted (Fc) 
respectively. Values of F and Fc are given in Sec. 60.45(f) 
of part 60, as applicable.

    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 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 quarterly 
summary.
    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 quarterly 
summary.
    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

[[Page 380]]

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]

                        Appendixes Q-R [Reserved]

      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 an area designated in 40 CFR 81.300 et seq., 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 an NAAQS (nonattainment area) 
under 40 CFR 81.300 et seq., this Interpretative Ruling will be 
superseded after June 30, 1979--(a) by preconstruction review provisions 
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 any air pollutant subject to 
regulation under the Act.
    2. 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).
    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

[[Page 381]]

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 any pollutant subject to 
regulation under the Act; or
    (b) Any physical change that would occur at a stationary source not 
qualifying under paragraph 5.(i)(a) of section II of this appendix 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 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 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;
    (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 significant net emissions increase of any pollutant subject to 
regulation under the Act.
    (ii) Any net emissions increase that is considered 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 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.
    6. (i) Net emissions increase means the amount by which the sum of 
the following exceeds zero:
    (a) Any increase in actual emissions from a particular physical 
change or change in the method of operation at a stationary source; and
    (b) Any other increases and decreases in actual emissions at the 
source that are contemporaneous with the particular change and are 
otherwise creditable.
    (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 Administrator has not relied on it in issuing a permit

[[Page 382]]

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 federally enforceable 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 51.18; 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.
    7. Emissions unit means any part of a stationary source which emits 
or would have the potential to emit any pollutant subject to regulation 
under the Act.
    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 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
Particulate matter: 25 tpy of particulate matter emissions
Ozone: 40 tpy of volatile organic compounds
Lead: 0.6 tpy
    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 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 
pollutant from an emissions unit as determined in accordance with 
paragraphs 16. (ii) through (iv) of Section II.A. of this appendix.
    (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 two-year 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 which has not begun normal operations on 
the particular date, actual emissions shall equal the potential to emit 
of the unit on that date.

[[Page 383]]

    14. Construction means any physical change or change in the method 
of operation (including fabrication, erection, installation, demolition, 
or modification of an emissions unit) which would result in a change in 
actual 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 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.
    B. Review of all sources for emission limitation compliance. The 
reviewing authority must examine each proposed major new source and 
proposed major modification 1to determine if such a source 
will meet all applicable emission requirements in the SIP, any 
applicable new source performance standard in 40 CFR part 60, or any 
national emission standard for hazardous air pollutants in 40 CFR part 
61. If the reviewing authority determines that the proposed major new 
source cannot meet the applicable 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 emissions 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 the 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;

[[Page 384]]

    (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 g/m3.....  5 g/m3.......  .....................  25 g/m3.....  .....................
TSP................................  1.0 g/m3.....  5 g/m3.......  .....................  .....................  .....................
NO2................................  1.0 g/m3.....  ......................  .....................  .....................  .....................
CO.................................  ......................  ......................  0.5 mg/m3............  .....................  2 mg/m3.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    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 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:

[[Page 385]]

    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.
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    \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.
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    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.\5\
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    \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.
    \5\ Required only for those pollutants for which the increased 
allowable emissions exceed 50 tons per year, 1000 pounds per day, or 100 
pounds per hour, although the reviewing authority may address other 
pollutants if deemed appropriate. The preceding hourly and daily rates 
shall apply only with respect to a pollutant for which a national 
ambient air quality standard, for a period less than 24 hours or for a 
24-hour period, as appropriate, has been established.
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    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 appplicant) 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 \6\ 
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.\7\
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    \6\ Subject to the provisions of section IV.C. below.
    \7\ The discussion in this paragraph is a proposal, but represents 
EPA's interim policy until final rulemaking is completed.
---------------------------------------------------------------------------

    Only intrapollutant emission offsets will be acceptable (e.g., 
hydrocarbon increases may not be offset against SO2 
reductions).
    Condition 4. The emission offsets will provide a positive net air 
quality benefit in the affected area (see Section IV.D. below).\8\ 
Atmospheric simulation modeling is not necessary for volatile organic 
compounds and NOX. Fulfillment of Condition 3 and Section

[[Page 386]]

IV.D. will be considered adequate to meet this condition.
---------------------------------------------------------------------------

    \8\ Required only for those pollutants for which the increased 
allowable emissions exceed 50 tons per year, 1000 pounds per day, or 100 
pounds per hour, although the reviewing authority may address other 
pollutants if deemed appropriate. The preceding hourly and daily rates 
shall apply only with respect to a pollutant for which a national 
ambient air quality standard, for a period less than 24 hours or for a 
24-hour period, as appropriate, has been established.
---------------------------------------------------------------------------

    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 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. (i) Operating hours and source shutdown.
    A source may generally be credited with emissions reductions 
achieved by shutting down an existing source or permanently curtailing 
production or operating hours below baseline levels (see initial 
discussion in this Section IV.C), if such reductions are permanent, 
quantifiable, and federally enforceable, and if the area has an EPA-
approved attainment plan. In addition, the shutdown or curtailment is 
creditable only if it occurred on or after the date specified for this 
purpose in the plan, and if such date is on or after the date of the 
most recent emissions inventory used in the plan's demonstration of 
attainment. Where the plan does not specify a cutoff date for shutdown 
credits, the date of the most recent emissions inventory or attainment 
demonstration, as the case may be, shall apply. However, in no event may 
credit be given for shutdowns which occurred prior to August 7, 1977. 
For purposes of this paragraph, a permitting authority may choose to 
consider a prior shutdown or curtailment to have occurred after the date 
of its most recent emissions inventory, if the inventory

[[Page 387]]

explicitly includes as current ``existing'' emissions the emissions from 
such previously shutdown or curtailed sources.
    (ii) Such reductions may be credited in the absence of an approved 
attainment demonstration only if the shutdown or curtailment occurred on 
or after the date the new source application is filed, or, if the 
applicant can establish that the proposed new source is a replacement 
for the shutdown or curtailed source and the cutoff date provisions of 
section IV.C.3.(i) are observed.
    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. In the case of emission offsets 
involving volatile organic compounds (VOC), the offsets may be obtained 
from sources located anywhere in the broad vicinity of the proposed new 
source. Generally, offsets will be acceptable if obtained from within 
the same AQCR as the new source or from other areas which may be 
contributing to the ozone problem at the proposed new source location. 
As with other pollutants, it is desirable to obtain offsets from sources 
located as close to the proposed new source site as possible. If the 
proposed offsets would be from sources located at greater distances from 
the new source, the reviewing authority should increase the ratio of the 
required offsets and require a showing that nearby offsets were 
investigated and reasonable alternatives were not available.9
---------------------------------------------------------------------------

    \9\ The discussion in this paragraph is a proposal, but represents 
EPA's interim policy until final rulemaking is completed.
---------------------------------------------------------------------------

    Offsets for NOX sources may also be obtained within the 
broad vicinity of the proposed new source. This is because areawide 
ozone and NO2 levels are generally not as dependent on 
specific VOC or NOX source location as they are on overall 
area emissions. Since the air quality impact of SO2, 
particulate and carbon monoxide sources is site dependent, simple 
areawide mass emission offsets are not appropriate. For these 
pollutants, the reviewing authority should consider atmospheric 
simulation modeling to ensure that the emission offsets provide a 
positive net air quality benefit. However, to avoid unnecessary 
consumption of limited, costly and time consuming modeling resources, in 
most cases it can be assumed that if the emission offsets are obtained 
from an existing source on the same premises or in the immediate 
vicinity of the new source, and the pollutants disperse from 
substantially the same effective stack height, the air quality test 
under Condition 4 of Section IV.A. of this appendix will be met. Thus, 
when stack emissions are offset against a ground level source at the 
same site, modeling would be required. The reviewing authority may 
perform this analysis or require the applicant to submit appropriate 
modeling results.
    E. Reasonable progress towards attainment. As long as the emission 
offset is greater than one-for-one, and the other criteria set forth

[[Page 388]]

above are met, EPA does not intend to question a reviewing authority's 
judgment as to what constitutes reasonable progress towards attainment 
as required under Condition 3 in Section IV.A. of this appendix. This 
does not apply to ``reasonable further progress'' as required by Section 
173.
    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.

                      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.10 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.
---------------------------------------------------------------------------

    \10\ 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 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 81.3000 et seq. as 
nonattainment (or, where Section III of this Ruling is applicable, a new 
source which would cause or contribute to an NAAQS violation) may be 
exempt from the Conditions of Section IV. A.

[[Page 389]]

so long as the new source meets the applicable SIP emissions limitations 
and will not interfere with the attainment date specified in the SIP 
under section 110 of the Act.

(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)))

[44 FR 3282, Jan. 16, 1979, as amended at 45 FR 31311, May 13, 1980; 45 
FR 52741, Aug. 7, 1980; 45 FR 59879, Sept. 11, 1980; 46 FR 50771, Oct. 
14, 1981; 47 FR 27561, June 25, 1982; 49 FR 43210, Oct. 26, 1984; 51 FR 
40661, 40675, Nov. 7, 1986; 52 FR 24714, July 1, 1987; 52 FR 29386, Aug 
7, 1987; 54 FR 27285, 27299, June 28, 1989; 57 FR 3946, Feb. 3, 1992]

                        Appendixes T-U [Reserved]

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 letter of submittal from the Governor or his designee, 
requesting EPA approval of the plan or revision thereof (hereafter ``the 
plan'').
    (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 to the existing approved plan, where 
applicable. The submittal shall be a copy of the official State 
regulation /document signed, stamped, dated by the appropriate State 
official indicating that it is fully enforceable by the State. The 
effective date of the regulation/document shall, whenever possible, be 
indicated in the document itself.
    (e) Evidence that the State followed all of the procedural 
requirements of the State's 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 hearings(s) were held in accordance 
with the information provided in the public notice and the State's laws 
and constitution, if applicable.
    (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

[[Page 390]]

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.

[55 FR 5830, Feb. 16, 1990, as amended at 56 FR 42219, Aug. 26, 1991; 56 
FR 57288, Nov. 8, 1991]

         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, 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 used in assessing control 
strategies and developing emission 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. Four primary on-going 
activities provide direct input to revisions of the Guideline. The first 
is a series of annual EPA workshops conducted for the purpose of 
ensuring consistency and providing clarification in the application of 
models. The second activity, directed toward the improvement of modeling 
procedures, is the cooperative agreement that EPA has with the 
scientific community represented by the American Meteorological Society. 
This agreement provides scientific assessment of procedures and proposed 
techniques and sponsors workshops on key technical issues. The third 
activity is 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 EPA of privately developed models. 
After extensive evaluation and scientific review, these models, as well 
as those made available by EPA, are considered for recognition in the 
Guideline. The fourth activity is the extensive on-going research 
efforts by EPA and others in air quality and meteorological modeling.
    c. Based primarily on these four activities, this document embodies 
all revisions to the Guideline Although the text has been revised from 
the original 1978 guide, the present content and topics are similar. As 
necessary, new sections and topics are included. EPA does not make 
changes to the guidance on a predetermined schedule, but rather on an as 
needed basis. 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

[[Page 391]]

proposed and finalized in the Federal Register. Information on the 
current status of modeling guidance can always be obtained from EPA's 
Regional Offices.

                            Table of Contents

                             List of Tables

1.0 Introduction
2.0 Overview of Model Use
    2.1 Suitability of Models
    2.2 Classes of Models
    2.3 Levels of Sophistication of Models
3.0 Recommended Air Quality Models
    3.1 Preferred Modeling Techniques
    3.1.1 Discussion
    3.1.2 Recommendations
    3.2 Use of Alternative Models
    3.2.1 Discussion
    3.2.2 Recommendations
    3.3 Availability of Supplementary Modeling Guidance
    3.3.1 The Model Clearinghouse
    3.3.2 Regional Meteorologists Workshops
4.0 Simple-Terrain Stationary Source Models
    4.1 Discussion
    4.2 Recommendations
    4.2.1 Screening Techniques
    4.2.2 Refined Analytical Techniques
5.0 Model Use in Complex Terrain
    5.1 Discussion
    5.2 Recommendations
    5.2.1 Screening Techniques
    5.2.2 Refined Analytical Techniques
6.0 Models for Ozone, Carbon Monoxide and Nitrogen Dioxide
    6.1 Discussion
    6.2 Recommendations
    6.2.1 Models for Ozone
    6.2.2 Models for Carbon Monoxide
    6.2.3 Models for Nitrogen Dioxide (Annual Average)
7.0 Other Model Requirements
    7.1 Discussion
    7.2 Recommendations
    7.2.1 Fugitive Dust/Fugitive Emissions
    7.2.2 Particulate Matter
    7.2.3 Lead
    7.2.4 Visibility
    7.2.5 Good Engineering Practice Stack Height
    7.2.6 Long Range Transport (LRT) (i.e., beyond 50km)
    7.2.7 Modeling Guidance for Other Governmental Programs
    7.2.8 Air Pathway Analyses (Air Toxics and Hazardous Waste)
8.0 General Modeling Considerations
    8.1 Discussion
    8.2 Recommendations
    8.2.1 Design Concentrations
    8.2.2 Critical Receptor Sites
    8.2.3 Dispersion Coefficients
    8.2.4 Stability Categories
    8.2.5 Plume Rise
    8.2.6 Chemical Transformation
    8.2.7 Gravitational Settling and Deposition
    8.2.8 Urban/Rural Classification
    8.2.9 Fumigation
    8.2.10 Stagnation
    8.2.11 Calibration of Models
9.0 Model Input Data
    9.1 Source Data
    9.1.1 Discussion
    9.1.2 Recommendations
    9.2 Background Concentrations
    9.2.1 Discussion
    9.2.2 Recommendations (Isolated Single Source)
    9.2.3 Recommendations (Multi-Source Areas)
    9.3 Meteorological Input Data
    9.3.1 Length of Record of Meteorological Data
    9.3.2 National Weather Service Data
    9.3.3 Site-Specific Data
    9.3.4 Treatment of Calms
10.0 Accuracy and Uncertainty of Models
    10.1 Discussion
    10.1.1 Overview of Model Uncertainty
    10.1.2 Studies of Model Accuracy
    10.1.3 Use of Uncertainty in Decision-Making
    10.1.4 Evaluation of Models
    10.2 Recommendations
11.0 Regulatory Application of Models
    11.1 Discussion
    11.2 Recommendations
    11.2.1 Analysis Requirements
    11.2.2 Use of Measured Data in Lieu of Model Estimates
    11.2.3 Emission Limits
12.0 References
13.0 Bibliography
14.0 Glossary of Terms
Appendix A to Appendix W of Part 51--Summaries of Preferred Air Quality 
          Models
Appendix B to Appendix W of Part 51--Summaries of Alternative Air 
          Quality Models
Appendix C to Appendix W of Part 51--Example Air Quality Analysis 
          Checklist

                             List of Tables
------------------------------------------------------------------------
 Table
  No.                                 Title
------------------------------------------------------------------------
5-1a..  Neutral/Stable Meteorological Matrix for CTSCREEN.
5-1b..  Unstable/Convective Meteorological Matrix for CTSCREEN.
5-2...  Preferred Options for the SHORTZ/LONGZ Computer Codes When Used
         in a Screening Mode.
5-3...  Preferred Options for the RTDM Computer Code When Used in a
         Screening Mode.
9-1...  Model Emission Input Data for Point Sources.
9-2...  Point Source Model Input Data (Emissions) for PSD NAAQS
         Compliance Demonstrations.
9-3...  Averaging Times for Site-Specific Wind and Turbulence
         Measurements.
------------------------------------------------------------------------

                            1.0 Introduction

    a. The Guideline recommends air quality modeling techniques that 
should be applied

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to State Implementation Plan (SIP) \1\ revisions for existing sources 
and to new source reviews,\2\ including prevention of significant 
deterioration (PSD).\3\ It is intended for use by EPA Regional Offices 
in judging the adequacy of modeling analyses performed by EPA, State and 
local agencies and by industry. The guidance is appropriate for use by 
other Federal agencies and by State agencies with air quality and land 
management responsibilities. The Guideline serves to identify, for all 
interested parties, those techniques and data bases EPA considers 
acceptable. The guide is not intended to be a compendium of modeling 
techniques. Rather, it should serve as a basis by which air quality 
managers, supported by sound scientific judgment, have a common measure 
of acceptable technical analysis.
    b. Due to limitations in the spatial and temporal coverage of air 
quality measurements, monitoring data normally are not sufficient as the 
sole basis for demonstrating the adequacy of emission limits for 
existing sources. Also, the impacts of new sources that do not yet exist 
can only be determined through modeling. Thus, models, while uniquely 
filling one program need, have become a primary analytical tool in most 
air quality assessments. Air quality measurements though can be used in 
a complementary manner to dispersion models, with due regard for the 
strengths and weaknesses of both analysis techniques. Measurements are 
particularly useful in assessing the accuracy of model estimates. The 
use of air quality measurements alone however could be preferable, as 
detailed in a later section of this document, when models are found to 
be unacceptable and monitoring data with sufficient spatial and temporal 
coverage are available.
    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 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 States and EPA Regional Offices, by many industries and 
trade associations, and also by the deliberations of Congress, that 
consistency in the selection and application of models and data bases 
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 emission limits. Such consistency is not, 
however, promoted at the expense of model and data base accuracy. This 
guide provides a consistent basis for selection of the most accurate 
models and data bases for use in air quality assessments.
    e. Recommendations are made in this guide concerning air quality 
models, data bases, requirements for concentration estimates, the use of 
measured data in lieu of model estimates, and model evaluation 
procedures. Models are identified for some specific applications. The 
guidance provided here should be followed in all air quality analyses 
relative to State Implementation Plans and in analyses required by EPA, 
State and local agency air programs. The EPA may approve the use of 
another technique that can be demonstrated to be more appropriate than 
those recommended in this guide. This is discussed at greater length in 
section 3.0. In all cases, the model 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 this guide 
should be carefully documented and fully supported.
    f. From time to time situations arise requiring clarification of the 
intent of the guidance on a specific topic. Periodic workshops are held 
with the EPA Regional Meteorologists to ensure consistency in modeling 
guidance and to promote the use of more accurate air quality models and 
data bases. The workshops serve to provide further explanations of 
Guideline requirements to the Regional Offices and workshop reports are 
issued with this clarifying information. In addition, findings from on-
going research programs, new model submittals, or results from model 
evaluations and applications are continuously evaluated. Based on this 
information changes in the guidance may be indicated.
    g. All changes to the Guideline must follow rulemaking requirements 
since the Guideline is codified in this appendix W of part 51. EPA will 
promulgate proposed and final rules in the Federal Register to amend 
this

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appendix W. Ample opportunity for public comment will be provided for 
each proposed change and public hearings scheduled if requested.
    h. A wide range of topics on modeling and data bases are discussed 
in the Guideline. Chapter 2 gives an overview of models and their 
appropriate use. Chapter 3 provides specific guidance on the use of 
``preferred'' air quality models and on the selection of alternative 
techniques. Chapters 4 through 7 provide recommendations on modeling 
techniques for application to simple-terrain stationary source problems, 
complex terrain problems, and mobile source problems. Specific modeling 
requirements for selected regulatory issues are also addressed. Chapter 
8 discusses issues common to many modeling analyses, including 
acceptable model components. Chapter 9 makes recommendations for data 
inputs to models including source, meteorological and background air 
quality data. Chapter 10 covers the uncertainty in model estimates and 
how that information can be useful to the regulatory decision-maker. The 
last chapter summarizes how estimates and measurements of air quality 
are used in assessing source impact and in evaluating control 
strategies.
    i. This appendix W itself contains three appendices: A, B, and C. 
Thus, when reference is made to ``Appendix A'', it refers to appendix A 
to this appendix W. Appendices B and C are referenced in the same way.
    j. Appendix A contains summaries of refined air quality models that 
are ``preferred'' for specific applications; both EPA models and models 
developed by others are included. Appendix B contains summaries of other 
refined models that may be considered with a case-specific 
justification. Appendix C contains a checklist of requirements for an 
air quality analysis.

                        2.0 Overview of Model Use

    a. Before attempting to implement the guidance contained in this 
appendix, the reader should be aware of certain general information 
concerning air quality models and their 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 evaluation of source impact depends upon several factors. These 
include: (1) The meteorological and topographic complexities of the 
area; (2) the level of detail and accuracy needed for the analysis; (3) 
the technical competence of those undertaking such simulation modeling; 
(4) the resources available; and (5) the detail and accuracy of the data 
base, i.e., emissions inventory, meteorological data, and air quality 
data. Appropriate data should be available before any attempt is made to 
apply a model. A model that requires detailed, precise, input data 
should not be used when such data are unavailable. However, assuming the 
data are adequate, the greater the detail with which a model considers 
the spatial and temporal variations in emissions and meteorological 
conditions, the greater the ability to evaluate the source impact and to 
distinguish the effects of various control strategies.
    b. Air quality models have been applied with the most accuracy or 
the least degree of uncertainty to simulations of long term averages in 
areas with relatively simple topography. Areas subject to major 
topographic influences experience meteorological complexities that are 
extremely difficult to simulate. Although models are available for such 
circumstances, they are frequently site specific and resource intensive. 
In the absence of a model capable of simulating such complexities, only 
a preliminary approximation may be feasible until such time as better 
models and data bases become available.
    c. Models are highly specialized tools. Competent and experienced 
personnel are an essential prerequisite to the successful application of 
simulation models. The need for specialists is critical when the more 
sophisticated models are used or the area being investigated has 
complicated meteorological or topographic features. A model applied 
improperly, or with inappropriately chosen data, can lead to serious 
misjudgments regarding the source impact or the effectiveness of a 
control strategy.
    d. The resource demands generated by use of air quality models vary 
widely depending on the specific application. The resources required 
depend on the nature of the model and its complexity, the detail of the 
data base, the difficulty of the application, and the amount and level 
of expertise required. The costs of manpower and computational 
facilities may also be important factors in the selection and use of a 
model for a specific analysis. However, it should be recognized that 
under some sets of physical circumstances and accuracy requirements, no 
present model may be appropriate. Thus, consideration of these factors 
should not lead to selection of an inappropriate model.

                          2.2 Classes of Models

    a. The air quality modeling procedures discussed in this guide can 
be categorized into four generic classes: Gaussian, numerical, 
statistical or empirical, and physical. Within these classes, especially 
Gaussian and numerical models, a large number of individual 
``computational algorithms'' may exist, each with its own specific 
applications. While each of the algorithms may have the same generic 
basis, e.g., Gaussian, it is accepted practice to refer to them 
individually as models. For example, the Industrial Source Complex (ISC) 
model and the RAM model are

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commonly referred to as individual models. In fact, they are both 
variations of a basic Gaussian model. In many cases the only real 
difference between models within the different classes is the degree of 
detail considered in the input or output data.
    b. Gaussian models are the most widely used techniques for 
estimating the impact of nonreactive pollutants. Numerical models may be 
more appropriate than Gaussian models for area source urban applications 
that involve reactive pollutants, but they require much more extensive 
input data bases and resources and therefore are not as widely applied. 
Statistical or empirical techniques are frequently employed in 
situations where incomplete scientific understanding of the physical and 
chemical processes or lack of the required data bases make the use of a 
Gaussian or numerical model impractical. Various specific models in 
these three generic types are discussed in the Guideline.
    c. Physical modeling, the fourth generic type, involves the use of 
wind tunnel or other fluid modeling facilities. This class of modeling 
is a complex process requiring a high level of technical expertise, as 
well as access to the necessary facilities. Nevertheless, physical 
modeling may be useful for complex flow situations, such as building, 
terrain or stack downwash conditions, plume impact on elevated terrain, 
diffusion in an urban environment, or diffusion in complex terrain. It 
is particularly applicable to such situations for a source or group of 
sources in a geographic area limited to a few square kilometers. If 
physical modeling is available and its applicability demonstrated, it 
may be the best technique. A discussion of physical modeling is beyond 
the scope of this guide. The EPA publication ``Guideline for Fluid 
Modeling of Atmospheric Diffusion,''\4\ provides information on fluid 
modeling applications and the limitations of that method.

                 2.3 Levels of Sophistication of Models

    a. In addition to the various classes of models, there are two 
levels of sophistication. The first level consists of general, 
relatively simple estimation techniques that provide conservative 
estimates of the air quality impact of a specific source, or source 
category. These are screening techniques or screening models. The 
purpose of such techniques is to eliminate the need of further more 
detailed modeling for those sources that clearly will not cause or 
contribute to ambient concentrations in excess of either the National 
Ambient Air Quality Standards (NAAQS) \5\ or the allowable prevention of 
significant deterioration (PSD) concentration increments.\3\ If a 
screening technique indicates that the concentration contributed by the 
source exceeds the PSD increment or the increment remaining to just meet 
the NAAQS, then the second level of more sophisticated models should be 
applied.
    b. The second level consists of those analytical techniques that 
provide more detailed treatment of physical and chemical atmospheric 
processes, require more detailed and precise input data, and provide 
more specialized concentration estimates. As a result they provide a 
more refined and, at least theoretically, a more accurate estimate of 
source impact and the effectiveness of control strategies. These are 
referred to as refined models.
    c. The use of screening techniques followed by a more refined 
analysis is always desirable, however there are situations where the 
screening techniques are practically and technically the only viable 
option for estimating source impact. In such cases, an attempt should be 
made to acquire or improve the necessary data bases and to develop 
appropriate analytical techniques.

                   3.0 Recommended Air Quality Models

    a. This section recommends refined modeling techniques that are 
preferred for use in regulatory air quality programs. The status of 
models developed by EPA, as well as those submitted to EPA for review 
and possible inclusion in this guidance, is discussed. The section also 
addresses the selection of models for individual cases and provides 
recommendations for situations where the preferred models are not 
applicable. Two additional sources of modeling guidance, the Model 
Clearinghouse \6\ and periodic Regional Meteorologists' workshops, are 
also briefly discussed here.
    b. In all regulatory analyses, especially if other than preferred 
models are selected for use, early discussions among Regional Office 
staff, State and local control agencies, industry representatives, and 
where appropriate, the Federal Land Manager, are invaluable and are 
encouraged. Agreement on the data base to be used, modeling techniques 
to be applied and the overall technical approach, prior to the actual 
analyses, helps avoid misunderstandings concerning the final results and 
may reduce the later need for additional analyses. The use of an air 
quality checklist, such as presented in appendix C, and the preparation 
of a written protocol help to keep misunderstandings at a minimum.
    c. It should not be construed 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 
models is needed to promote consistency in model selection and 
application.
    d. The 1980 solicitation of new or different models from the 
technical community \7\ and

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the program whereby these models are evaluated, established a means by 
which new models are identified, reviewed and made available in the 
Guideline. There is a pressing need for the development of models for a 
wide range of regulatory applications. Refined models that more 
realistically simulate the physical and chemical process in the 
atmosphere and that more reliably estimate pollutant concentrations are 
required. Thus, the solicitation of models is considered to be 
continuous.

                    3.1 Preferred Modeling Techniques

                            3.1.1 Discussion

    a. EPA has developed approximately 10 models suitable for regulatory 
application. More than 20 additional models were submitted by private 
developers for possible inclusion in the Guideline. These refined models 
have all been organized into eight categories of use: rural, urban 
industrial complex, reactive pollutants, mobile sources, complex 
terrain, visibility, and long range transport. They are undergoing an 
intensive evaluation by category. The evaluation exercises 
8 9 10 include statistical measures of model performance in 
comparison with measured air quality data as suggested by the American 
Meteorological Society \11\ and, where possible, peer scientific 
reviews.12 13 l4
    b. When a single model is found to perform better than others in a 
given category, it is recommended for application in that category 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 is selected on the basis of other 
factors such as past use, public familiarity, cost or resource 
requirements, and availability. No further evaluation of a preferred 
model is required if the source follows EPA recommendations specified 
for the model in the Guideline. The models not specifically recommended 
for use in a particular category are summarized in appendix B. These 
models should be compared with measured air quality data when they are 
used for regulatory applications consistent with recommendations in 
section 3.2.
    c. The solicitation of new refined models which are based on sounder 
scientific principles and which more reliably estimate pollutant 
concentrations is considered by EPA to be continuous. Models that are 
submitted in accordance with the provisions outlined in the Federal 
Register notice of March 1980 (45 FR 20157) \7\ will be evaluated as 
submitted. These requirements are:
    i. The model must be computerized and functioning in a common 
Fortran language suitable for use on a variety of computer systems.
    ii. The model must be documented in a user's guide which identifies 
the mathematics of the model, data requirements and program operating 
characteristics at a level of detail comparable to that available for 
currently recommended models, e.g., the Industrial Source Complex (ISC) 
model.
    iii. The model must be accompanied by a complete test data set 
including input parameters and output results. The test data must be 
included in the user's guide as well as provided in computer-readable 
form.
    iv. The model must be useful to typical users, e.g., State air 
pollution control 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 comparison with air 
quality data or with other well-established analytical techniques.
    vi. The developer must be willing to make the model available to 
users at reasonable cost or make it available for public access through 
the National Technical Information Service; the model cannot be 
proprietary.
    d. The evaluation process will include a determination of technical 
merit, in accordance with the above six items including the practicality 
of the model for use in ongoing regulatory programs. Each model will 
also be subjected to a performance evaluation for an appropriate data 
base and to a peer scientific review. Models for wide use (not just an 
isolated case!) found to perform better, based on an evaluation for the 
same data bases used to evaluate models in appendix A, will be proposed 
for inclusion as preferred models in future Guideline revisions.

                          3.1.2 Recommendations

    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 should select a model from appendix A. These 
models may be used without a formal demonstration of applicability as 
long as they are used as indicated in each model summary of appendix A. 
Further recommendations for the application of these models to specific 
source problems are found in subsequent sections of the Guideline.
    b. If changes are made to a preferred model without affecting the 
concentration estimates, 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 or those that affect only the 
format or averaging time of the model results. However, when any changes 
are made, the Regional Administrator should require a test case example 
to demonstrate that the concentration estimates are not affected.
    c. A preferred model should be operated with the options listed in 
appendix A as ``Recommendations for Regulatory Use.'' If other options 
are exercised, the model is no

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longer ``preferred.'' Any other modification to a preferred model that 
would result in a change in the concentration estimates likewise alters 
its status as a preferred model. Use of the model must then be justified 
on a case-by-case basis.

                      3.2 Use of Alternative Models

                            3.2.1 Discussion

    a. Selection of the best 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 guide cannot alone 
achieve that consistency nor can it necessarily provide the best model 
for all possible situations. An EPA document, ``Interim Procedures for 
Evaluating Air Quality Models'',15 16 has been prepared to 
assist in developing a consistent approach when justifying the use of 
other than the preferred modeling techniques recommended in this guide. 
An alternative to be considered to the performance measures contained in 
Chapter 3 of this document is set forth in another EPA document 
``Protocol for Determining the Best Performing Model''. \17\ The 
procedures in both documents provide a general framework for objective 
decision-making on the acceptability of an alternative model for a given 
regulatory application. The documents contain procedures for conducting 
both the technical evaluation of the model and the field test or 
performance evaluation.
    b. This section discusses the use of alternate modeling techniques 
and defines three situations when alternative models may be used.

                          3.2.2 Recommendations

    a. Determination of acceptability of a model is a Regional Office 
responsibility. Where the Regional Administrator finds that an 
alternative model is more appropriate than a preferred model, that model 
may be used subject to the recommendations below. 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 analytical procedure is available and is 
applicable.
    b. An alternative model should 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 will normally 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 
application than a comparable model in appendix A; and (3) if there is 
no preferred model for the specific application but a refined model is 
needed to satisfy regulatory requirements. Any one of these three 
separate conditions may warrant use of an alternative model. Some known 
alternative models that are applicable for selected situations are 
contained in appendix B. However, inclusion there does not infer any 
unique status relative to other alternative models that are being or 
will be developed in the future.
    c. Equivalency is established by demonstrating that the maximum or 
highest, second highest concentrations 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 so 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. Two percent was selected 
as the basis for equivalency since it is a rough approximation of the 
fraction that PSD Class I increments are of the NAAQS for 
SO2, i.e., the difference in concentrations that is judged to 
be significant. However, notwithstanding this demonstration, use of 
models that are not equivalent may be used when the conditions of 
paragraph e of this section are satisfied.
    d. The procedures and techniques for determining the acceptability 
of a model for an individual case based on superior performance is 
contained in the document entitled ``Interim Procedures for Evaluating 
Air Quality Models'', \15\ and should be followed, as 
appropriate.a Preparation and implementation of an evaluation 
protocol which is acceptable to both control agencies and regulated 
industry is an important element in such an evaluation.
---------------------------------------------------------------------------

    \a\ Another EPA document, ``Protocol for Determining the Best 
Performing Model'', \17\ contains advanced statistical techniques for 
determining which model performs better than other competing models. In 
many cases, this protocol should be considered by users of the ``Interim 
Procedures for Evaluating Air Quality Models'' in preference to the 
material currently in Chapter 3 of that document.
---------------------------------------------------------------------------

    e. When no appendix A model is applicable to the modeling problem, 
an alternative refined model may be used provided that:
    i. The model can be demonstrated to be applicable to the problem on 
a theoretical basis; and
    ii. The data bases which are necessary to perform the analysis are 
available and adequate; and
    iii. Performance evaluations of the model in similar circumstances 
have shown that the model is not biased toward underestimates; or

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    iv. After consultation with the EPA Regional Office, a second model 
is selected as a baseline or reference point for performance and the 
interim procedures \15\ protocol \17\ are then used to demonstrate that 
the proposed model performs better than the reference model.

           3.3 Availability of Supplementary Modeling Guidance

    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 and consistency in modeling decisions is fostered among the 
various Regional Offices and the States. To satisfy that need, EPA 
established the Model Clearinghouse and also holds periodic workshops 
with headquarters, Regional Office and State modeling representatives.

                      3.3.1 The Model Clearinghouse

                           3.3.1.1 Discussion

    a. The Model Clearinghouse is the single EPA focal point for review 
of air quality simulation models proposed for use in specific regulatory 
applications. Details concerning the Clearinghouse and its operation are 
found in the document, ``Model Clearinghouse: Operational Plan.'' \6\ 
Three primary functions of the Clearinghouse are:
    i. Review of decisions proposed by EPA Regional Offices on the use 
of modeling techniques and data bases.
    ii. Periodic visits to Regional Offices to gather information 
pertinent to regulatory model usage.
    iii. Preparation of an annual report summarizing activities of the 
Clearinghouse including specific determinations made during the course 
of the year.

                         3.3.1.2 Recommendations

    a. The Regional Administrator may request assistance from the Model 
Clearinghouse after an initial evaluation and decision has been reached 
concerning the application of a model, analytical technique or data base 
in a particular regulatory action. The Clearinghouse may also consider 
and evaluate the use of modeling techniques submitted in support of any 
regulatory action. Additional responsibilities are: (1) Review proposed 
action for consistency with agency policy; (2) determine technical 
adequacy; and (3) make recommendations concerning the technique or data 
base.

                 3.3.2 Regional Meteorologists Workshops

                           3.3.2.1 Discussion

    a. EPA conducts an annual in-house workshop for the purpose of 
mutual discussion and problem resolution among Regional Office modeling 
specialists, EPA research modeling experts, EPA Headquarters modeling 
and regulatory staff and representatives from State modeling programs. A 
summary of the issues resolved at previous workshops was issued in 1981 
as ``Regional Workshops on Air Quality Modeling: A Summary Report.'' 
\17\ That report clarified procedures not specifically defined in the 
1978 version of the Guideline and was issued to ensure the consistent 
interpretation of model requirements from Region to Region. Similar 
workshops for the purpose of clarifying Guideline procedures or 
providing detailed instructions for the use of those procedures are 
anticipated in the future.

                         3.3.2.2 Recommendations

    a. The 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.

               4.0 Simple-Terrain Stationary Source Models

                             4.1 Discussion

    a. Simple terrain, as used in this section, is considered to be an 
area where terrain features are all lower in elevation than the top of 
the stack of the source(s) in question. The models recommended in this 
section are generally used in the air quality impact analysis of 
stationary sources for most criteria pollutants. The averaging time of 
the concentration estimates produced by these models ranges from 1 hour 
to an annual average.
    b. Model evaluation exercises have been conducted to determine the 
``best, most appropriate point source model'' for use in simple 
terrain.8 12 However, no one model has been found to be 
clearly superior. Based on past use, public familiarity, and 
availability, ISC is the recommended model for a wide range of 
regulatory applications. Similar determinations were made for the other 
refined models that are identified in section 4.2.

                           4.2 Recommendations

                       4.2.1 Screening Techniques

    a. Point source screening techniques are an acceptable approach to 
air quality analyses. One such approach is contained in the EPA document 
``Screening Procedures for Estimating the Air Quality Impact of 
Stationary Sources''. \18\ A computerized version of the screening 
technique, SCREEN, is available.19 20 For the current version 
of SCREEN, see 12.0 References. \20\
    b. All screening procedures should be adjusted to the site and 
problem at hand. Close attention should be paid to whether the area

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should be classified urban or rural in accordance with section 8.2.8. 
The climatology of the area should be studied to help define the worst-
case meteorological conditions. Agreement should be reached between the 
model user and the reviewing authority on the choice of the screening 
model for each analysis, and on the input data as well as the ultimate 
use of the results.

                   4.2.2 Refined Analytical Techniques

    a. A brief description of preferred models for refined applications 
is found in appendix A. Also listed in appendix A are the model input 
requirements, the standard options that should be selected when running 
the program, and output options.
    b. When modeling for compliance with short term NAAQS and PSD 
increments is of primary concern, a short term model may also be used to 
provide long term concentration estimates. However, when modeling 
sources for which long term standards alone are applicable (e.g., lead), 
then the long term models should be used. The conversion from long term 
to short term concentration averages by any transformation technique is 
not acceptable in regulatory applications.

                    5.0 Model Use in Complex Terrain

                             5.1 Discussion

    a. For the purpose of the Guideline, complex terrain is defined as 
terrain exceeding the height of the stack being modeled. Complex terrain 
dispersion models are normally applied to stationary sources of 
pollutants such as SO2 and particulates.
    b. A major outcome from the EPA Complex Terrain Model Development 
project has been the publication of a refined dispersion model (CTDM) 
suitable for regulatory application to plume impaction assessments in 
complex terrain. \21\ Although CTDM as originally produced was only 
applicable to those hours characterized as neutral or stable, a computer 
code for all stability conditions, CTDMPLUS, \19\ together with a user's 
guide, \22\ and on-site meteorological and terrain data 
processors,23 24 is now available. Moreover, 
CTSCREEN,19 25 a version of CTDMPLUS that does not require 
on-site meteorological data inputs, is also available as a screening 
technique.
    c. The methods discussed in this section should be considered in two 
categories: (1) Screening techniques, and (2) the refined dispersion 
model, CTDMPLUS, discussed below and listed in appendix A.
    d. Continued improvements in ability to accurately model plume 
dispersion in complex terrain situations can be expected, e.g., from 
research on lee side effects due to terrain obstacles. New approaches to 
improve the ability of models to realistically simulate atmospheric 
physics, e.g., hybrid models which incorporate an accurate wind field 
analysis, will ultimately provide more appropriate tools for analyses. 
Such hybrid modeling techniques are also acceptable for regulatory 
applications after the appropriate demonstration and evaluation. \15\

                           5.2 Recommendations

    a. Recommendations in this section apply primarily to those 
situations where the impaction of plumes on terrain at elevations equal 
to or greater than the plume centerline during stable atmospheric 
conditions are determined to be the problem. If a violation of any NAAQS 
or the controlling increment is indicated by using any of the preferred 
screening techniques, then a refined complex terrain model may be used. 
Phenomena such as fumigation, wind direction shear, lee-side effects, 
building wake- or terrain-induced downwash, deposition, chemical 
transformation, variable plume trajectories, and long range transport 
are not addressed by the recommendations in this section.
    b. Where site-specific data are used for either screening or refined 
complex terrain models, a data base of at least 1 full-year of 
meteorological data is preferred. If more data are available, they 
should be used. Meteorological data used in the analysis should be 
reviewed for both spatial and temporal representativeness.
    c. 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. The plume under such conditions 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. In order to avoid excessively large computer 
runs due to such a large array of receptors, it is often desirable to 
model the area twice. The first model run would use a moderate number of 
receptors carefully located over the area of interest. The second model 
run would use a more dense array of receptors in areas showing potential 
for high concentrations, as indicated by the results of the first model 
run.
    d. When CTSCREEN or CTDMPLUS is used, digitized contour data must be 
first processed by the CTDM Terrain Processor \23\ to provide hill shape 
parameters in a format suitable for direct input to CTDMPLUS. Then the 
user supplies receptors either through an interactive program that is 
part of the model or directly, by using a text editor; using both 
methods to select receptors 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,

[[Page 399]]

multiple hills, it may be necessary to model the terrain both as a 
single feature and as multiple hills to determine design concentrations.
    e. The user is encouraged to confer with the Regional Office if any 
unresolvable problems are encountered with any screening or refined 
analytical procedures, e.g., meteorological data, receptor siting, or 
terrain contour processing issues.

                       5.2.1 Screening Techniques

    a. Five preferred screening techniques are currently available to 
aid in the evaluation of concentrations due to plume impaction during 
stable conditions: (1) for 24-hour impacts, the Valley Screening 
Technique \19\ as outlined in the Valley Model User's Guide; \26\ (2) 
CTSCREEN,\19\ as outlined in the CTSCREEN User's Guide; \25\ (3) COMPLEX 
I; \19\ (4) SHORTZ/LONGZ; 19 27 and (5) Rough Terrain 
Dispersion Model (RTDM) 19 90 in its prescribed mode 
described below. As appropriate, any of these screening techniques may 
be used consistent with the needs, resources, and available data of the 
user.
    b. The Valley Model, COMPLEX I, SHORTZ/LONGZ, and RTDM should be 
used only to estimate concentrations at receptors whose elevations are 
greater than or equal to plume height. For receptors at or below stack 
height, a simple terrain model should be used (see Chapter 4). Receptors 
between stack height and plume height present a unique problem since 
none of the above models were designed to handle receptors in this 
narrow regime, the definition of which will vary hourly as 
meteorological conditions vary. CTSCREEN may be used to estimate 
concentrations under all stability conditions at all receptors located 
``on terrain'' above stack top, but has limited applicability in multi-
source situations. As a result, the estimation of concentrations at 
receptors between stack height and plume height should be considered on 
a case-by-case basis after consultation with the EPA Regional Office; 
the most appropriate technique may be a function of the actual source(s) 
and terrain configuration unique to that application. One technique that 
will generally be acceptable, but is not necessarily preferred for any 
specific application, involves applying both a complex terrain model 
(except for the Valley Model) and a simple terrain model. The Valley 
Model should not be used for any intermediate terrain receptor. For each 
receptor between stack height and plume height, an hour-by-hour 
comparison of the concentration estimates from both models is made. The 
higher of the two modeled concentrations should be chosen to represent 
the impact at that receptor for that hour, and then used to compute the 
concentration for the appropriate averaging time(s). For the simple 
terrain models, terrain may have to be ``chopped off'' at stack height, 
since these models are frequently limited to receptors no greater than 
stack height.

                   5.2.1.1 Valley Screening Technique

    a. The Valley Screening Technique may be used to determine 24-hour 
averages. This technique uses the Valley Model with the following worst-
case assumptions for rural areas: (1) P-G stability ``F''; (2) wind 
speed of 2.5 m/s; and (3) 6 hours of occurrence. For urban areas the 
stability should be changed to ``P-G stability E.''
    b. When using the Valley Screening Technique to obtain 24-hour 
average concentrations the following apply: (1) multiple sources should 
be treated individually and the concentrations for each wind direction 
summed; (2) only one wind direction should be used (see User's 
Guide,\26\ page 2-15) even if individual runs are made for each source; 
(3) for buoyant sources, the BID option may be used, and the option to 
use the 2.6 stable plume rise factor should be selected; (4) if plume 
impaction is likely on any elevated terrain closer to the source than 
the distance from the source to the final plume rise, then the 
transitional (or gradual) plume rise option for stable conditions should 
be selected.
    c. The standard polar receptor grid found in the Valley Model User's 
Guide may not be sufficiently dense for all analyses if only one 
geographical scale factor is used. The user should choose an additional 
set of receptors at appropriate downwind distances whose elevations are 
equal to plume height minus 10 meters. Alternatively, the user may 
exercise the ``Valley equivalent'' option in COMPLEX I or SCREEN and 
note the comments above on the placement of receptors in complex terrain 
models.
    d. When using the ``Valley equivalent'' option in COMPLEX I, set the 
wind profile exponents (PL) to 0.0, respectively, for all six stability 
classes.

                            5.2.1.2 CTSCREEN

    a. CTSCREEN may 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 model description and user's instructions are 
contained in the user's guide. \25\ The terrain data must be digitized 
in the same manner as for CTDMPLUS and a terrain processor is available. 
\23\ A discussion of the model's performance characteristics is provided 
in a technical paper. \91\ CTSCREEN is designed to execute a fixed 
matrix of meteorological values for wind speed (u), standard deviation 
of horizontal and vertical wind

[[Page 400]]

speeds (v, G5w), vertical potential 
temperature gradient (d/dz), friction velocity 
(ux), 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. Table 5-1 contains 
the matrix of meteorological variables that is used for each CTSCREEN 
analysis. There are 96 combinations, including exceptions, for each wind 
direction for the neutral/stable case, and 108 combinations for the 
unstable case. The specification of wind direction, however, is handled 
internally, based on the source and terrain geometry. The matrix was 
developed from examination of the range of meteorological variables 
associated with maximum monitored concentrations from the data bases 
used to evaluate the performance of CTDMPLUS. Although CTSCREEN is 
designed to address a single source scenario, there are a number of 
options that can be selected on a case-by-case basis to address multi-
source situations. However, the Regional Office should be consulted, and 
concurrence obtained, on the protocol for modeling multiple sources with 
CTSCREEN to ensure that the worst case is identified and assessed. 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.

                            5.2.1.3 COMPLEX I

    a. If the area is rural, COMPLEX I may be used to estimate 
concentrations for all averaging times. COMPLEX I is a modification of 
the MPTER model that incorporates the plume impaction algorithm of the 
Valley Model. \19\ It is a multiple-source screening technique that 
accepts hourly meteorological data as input. The output is the same as 
the normal MPTER output. When using COMPLEX I the following options 
should be selected: (1) Set terrain adjustment IOPT (1)=1; (2) set 
buoyancy induced dispersion IOPT (4)=1; (3) set IOPT (25)=1; (4) set the 
terrain adjustment values to 0.5, 0.5, 0.5 0.5, 0.0, 0.0, (respectively 
for six stability classes); and (5) set Z MIN=10.
    b. When using the ``Valley equivalent'' option (only) in COMPLEX I, 
set the wind profile exponents (PL) to 0.0, respectively, for all six 
stability classes. For all other regulatory uses of COMPLEX I, set the 
wind profile exponents to the values used in the simple terrain models, 
i.e., 0.07, 0.07, 0.10, 0.15, 0.35, and 0.55, respectively, for rural 
modeling.
    c. Gradual plume rise should be used to estimate concentrations at 
nearby elevated receptors, if plume impaction is likely on any elevated 
terrain closer to the source than the distance from the source to the 
final plume rise (see section 8.2.5).

                          5.2.1.4 SHORTZ/LONGZ

    a. If the source is located in an urbanized (Section 8.2.8) complex 
terrain valley, then the suggested screening technique is SHORTZ for 
short-term averages or LONGZ for long-term averages. SHORTZ and LONGZ 
may be used as screening techniques in these complex terrain 
applications without demonstration and evaluation. Application of these 
models in other than urbanized valley situations will require the same 
evaluation and demonstration procedures as are required for all appendix 
B models.
    b. Both SHORTZ and LONGZ have a number of options. When using these 
models as screening techniques for urbanized valley applications, the 
options listed in table 5-2 should be selected.

                      5.2.1.5 RTDM (Screening Mode)

    a. RTDM with the options specified in table 5-3 may be used as a 
screening technique in rural complex terrain situations without 
demonstration and evaluation.
    b. The RTDM screening technique can provide a more refined 
concentration estimate if on-site wind speed and direction 
characteristic of plume dilution and transport are used as input to the 
model. In complex terrain, these winds can seldom be estimated 
accurately from the standard surface (10m level) measurements. 
Therefore, in order to increase confidence in model estimates, EPA 
recommends that wind data input to RTDM should be based on fixed 
measurements at stack top height. For stacks greater than 100m, the 
measurement height may be limited to 100m in height relative to stack 
base. However, for very tall stacks, see guidance in section 9.3.3.2. 
This recommendation is broadened to include wind data representative of 
plume transport height where such data are derived from measurements 
taken with remote sensing devices such as SODAR. The data from both 
fixed and remote measurements should meet quality assurance and recovery 
rate requirements. The user should also be aware that RTDM in the 
screening mode accepts the input of measured wind speeds at only one 
height. The default values for the wind speed profile exponents shown in 
table 5-3 are used in the model to determine the wind speed at other 
heights. RTDM uses wind speed at stack top to calculate the plume rise 
and the critical dividing streamline height, and the wind speed at plume 
transport level to calculate dilution. RTDM treats wind direction as 
constant with height.
    c. RTDM makes use of the ``critical dividing streamline'' concept 
and thus treats plume interactions with terrain quite differently from 
other models such as SHORTZ

[[Page 401]]

and COMPLEX I. The plume height relative to the critical dividing 
streamline determines whether the plume impacts the terrain, or is 
lifted up and over the terrain. The receptor spacing to identify maximum 
impact concentrations is quite critical depending on the location of the 
plume in the vertical. Analysis of the expected plume height relative to 
the height of the critical dividing streamline should be performed for 
differing meteorological conditions in order to help develop an 
appropriate array of receptors. Then it is advisable to model the area 
twice according to the suggestions in section 5.2.

                          5.2.1.6 Restrictions

    a. For screening analyses using the Valley Screening Technique, 
COMPLEX I or RTDM, a sector greater than 22\1/2\ deg. should not be 
allowed. Full ground reflection should always be used in the Valley 
Screening Technique and COMPLEX I.

                   5.2.2 Refined Analytical Techniques

    a. When the results of the screening analysis demonstrate a possible 
violation of NAAQS or the controlling PSD increments, a more refined 
analysis may need to be conducted.
    b. The Complex Terrain Dispersion Model Plus Algorithms for Unstable 
Situations (CTDMPLUS) is a refined air quality model that is preferred 
for use in all stability conditions for complex terrain applications. 
CTDMPLUS is a sequential model that requires five input files: (1) 
General program specifications; (2) a terrain data file; (3) a receptor 
file; (4) a surface meteorological data file; and (5) a user created 
meteorological profile data file. Two optional input files consist of 
hourly emissions parameters and a file containing upper air data from 
rawinsonde data files, e.g., a National Climatic Data Center TD-6201 
file, unless there are no hours categorized as unstable in the record. 
The model description and user instructions are contained in Volume 1 of 
the User's Guide. \22\ Separate publications \23\ \24\ describe the 
terrain preprocessor system and the meteorological preprocessor program. 
In Part I of a technical article \92\ is a discussion of the model and 
its preprocessors; the model's performance characteristics are discussed 
in Part II of the same article.\93\ The size of the CTDMPLUS executable 
file on a personal computer is approximately 360K bytes. The model 
produces hourly average concentrations of stable pollutants, i.e., 
chemical transformation or decay of species and settling/deposition are 
not simulated. To obtain concentration averages corresponding to the 
NAAQS, e.g., 3- or 24-hour, or annual averages, the user must execute a 
postprocessor program such as CHAVG. \19\ CTDMPLUS is applicable to all 
receptors on terrain elevations above stack top. However, the model 
contains no algorithms for simulating building downwash or the mixing or 
recirculation found in cavity zones in the lee of a hill. The path taken 
by a plume through an array of hills cannot be simulated. CTDMPLUS does 
not explicitly simulate calm meteorological periods, and for those 
situations the user should follow the guidance in section 9.3.4. The 
user should follow the recommendations in the User's Guide under General 
Program Specifications for: (1) Selecting mixed layer heights, (2) 
setting minimum scalar wind speed to 1 m/s, and (3) scaling wind 
direction with height. Close coordination with the Regional Office is 
essential to insure a consistent, technically sound application of this 
model.
    c. The performance of CTDMPLUS is greatly improved by the use of 
meteorological data from several levels up to plume height. However, due 
to the vast range of source-plume-hill geometries possible in complex 
terrain, detailed requirements for meteorological monitoring in support 
of refined analyses using CTDMPLUS should be determined on a case-by-
case basis. The following general guidance should be considered in the 
development of a meteorological monitoring protocol for regulatory 
applications of CTDMPLUS and reviewed in detail by the Regional Office 
before initiating any monitoring. As appropriate, the On-Site 
Meteorological Program Guidance document \66\ should be consulted for 
specific guidance on siting requirements for meteorological towers, 
selection and exposure of sensors, etc. As more experience is gained 
with the model in a variety of circumstances, more specific guidance may 
be developed.
    d. Site specific meteorological data are critical to dispersion 
modeling in complex terrain and, consequently, the meteorological 
requirements are more demanding than for simple terrain. Generally, 
three different meteorological files (referred to as surface, profile, 
and rawin files) are needed to run CTDMPLUS in a regulatory mode.
    e. The surface file is created by the meteorological preprocessor 
(METPRO) \24\ based on on-site measurements or estimates of solar and/or 
net radiation, cloud cover and ceiling, and the mixed layer height. 
These data are used in METPRO to calculate the various surface layer 
scaling parameters (roughness length, friction velocity, and Monin-
Obukhov length) which are needed to run the model. All of the user 
inputs required for the surface file are based either on surface 
observations or on measurements at or below 10m.
    f. The profile data file is prepared by the user with on-site 
measurements (from at least three levels) of wind speed, wind direction, 
turbulence, and potential temperature. These measurements should be 
obtained up

[[Page 402]]

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 if the representative plume height(s) of interest exceed 100m. The 
meteorological tower need not exceed the lesser of the representative 
plume height of interest (the highest plume height if there is more than 
one plume height of interest) or 100m.
    g. Locating towers on nearby terrain to obtain stack height or plume 
height measurements for use in profiles by CTDMPLUS should be avoided 
unless it can clearly be demonstrated that such measurements would be 
representative of conditions affecting the plume.
    h. The rawin file is created by a second meteorological preprocessor 
(READ62) \24\ based on NWS (National Weather Service) upper air data. 
The rawin file is used in CTDMPLUS to calculate vertical potential 
temperature gradients for use in estimating plume penetration in 
unstable conditions. The representativeness of the off-site NWS upper 
air data should be evaluated on a case-by-case basis.
    i. In the absence of an appropriate refined model, screening results 
may need to be used to determine air quality impact and/or emission 
limits.

                          Table 5-1a--Neutral/Stable Meteorological Matrix for CTSCREEN
----------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------
    Variable                                                           Specific values
----------------------------------------------------------------------------------------------------------------
 
U (m/s)....................................          1.0           2.0          3.0            4.0           5.0
v (m/s)...........................          0.3           0.75
w (m/s)...........................          0.08          0.15         0.30           0.75
DQ/Dz (K/m)................................          0.01          0.02         0.035
WD                                               (Wind direction optimized internally for each meteorological
                                                                         combination)
----------------------------------------------------------------------------------------------------------------
Exceptions:
(1) If U  2 m/s and v  0.3 m/s, then include w = 0.04 m/s.
(2) If w = 0.75 m/s and U  3.0 m/s, then DU/Dz is limited to > 0.01 K/m.
(3) If U  4 m/s, then w  0.15 m/s.
(4) w > v


                       Table 5-1b--Unstable/Convective Meteorological Matrix for CTSCREEN
----------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------
    Variable                                                           Specific values
----------------------------------------------------------------------------------------------------------------
 
U (m/s)...................................         1.0             2.0            3.0           4.0          5.0
ux (m/s)..................................         0.1             0.3            0.5
L (m).....................................       -10             -50            -90
DU/Dz(K/m)                                         0.030  (potential temperature gradient above zi)
zi (m)....................................         0.5h            1.0h           1.5h
                                                    (where h = terrain height)
----------------------------------------------------------------------------------------------------------------


  Table 5-2--Preferred Options for the SHORTZ/LONGZ Computer Codes When
                        Used in a Screening Mode
------------------------------------------------------------------------
 
------------------------------------------------------------------------
Option                                                   Selection
------------------------------------------------------------------------
 
I Switch 9.................  ..........................  If using NWS
                                                          data, set = 0,
                                                          If using site-
                                                          specific data,
                                                          check with the
                                                          Regional
                                                          Office.
I Switch 17................  ..........................  Set = 1 (urban
                                                          option).
GAMMA 1....................  ..........................  Use default
                                                          values (0.6
                                                          entrainment
                                                          coefficient).
GAMMA 2....................  ..........................  Always default
                                                          to ``stable''.
XRY........................  ..........................  Set = 0 (50m
                                                          rectilinear
                                                          expansion
                                                          distance).
NS, VS, FRQ (SHORTZ)
                             (particle size, etc.)       Do not use
                                                          (applicable
                                                          only in flat
                                                          terrain).
NUS, VS, FRQ (LONGZ)
ALPHA......................  ..........................  Select 0.9.
SIGEPU
                             (dispersion parameters)...  Use Cramer
                                                          curves
                                                          (default); if
                                                          site-specific
                                                          turbulence
                                                          data are
                                                          available, see
                                                          Regional
                                                          Office for
                                                          advice.
SIGAPU
P (wind profile)...........  ..........................  Select default
                                                          values given
                                                          in table 2-2
                                                          of User's
                                                          Instructions;
                                                          if site-
                                                          specific data
                                                          are available,
                                                          see Regional
                                                          Office for
                                                          advice.
------------------------------------------------------------------------


[[Page 403]]


              Table 5-3--Preferred Options for the RTDM Computer Code When Used in a Screening Mode
----------------------------------------------------------------------------------------------------------------
             Parameter                      Variable                  Value                    Remarks
----------------------------------------------------------------------------------------------------------------
PR001-003..........................  SCALE.................  ......................  Scale factors assuming
                                                                                      horizontal distance is in
                                                                                      kilometers, vertical
                                                                                      distance is in feet, and
                                                                                      wind speed is in meters
                                                                                      per second.
PR004..............................  ZWIND1................  Wind measurement        See section 5.2.1.4.
                                                              height.
                                     ZWIND2................  Not used..............  Height of second
                                                                                      anemometer.
                                     IDILUT................  1.....................  Dilution wind speed scaled
                                                                                      to plume height.
                                     ZA....................  0 (default)...........  Anemometer-terrain height
                                                                                      above stack base.
PR005..............................  EXPON.................  0.09, 0.11, 0.12,       Wind profile exponents.
                                                              0.14, 0.2, 0.3
                                                              (default).
PR006..............................  ICOEF.................  3 (default)...........  Briggs Rural/ASME \139\
                                                                                      dispersion parameters.
PR009..............................  IPPP..................  0 (default)...........  Partial plume penetration;
                                                                                      not used.
PR010..............................  IBUOY.................  1 (default)...........  Buoyancy-enhanced
                                                                                      dispersion is used.
                                     ALPHA.................  3.162 (default).......  Buoyancy-enhanced
                                                                                      dispersion coefficient.
PR011..............................  IDMX..................  1 (default)...........  Unlimited mixing height for
                                                                                      stable conditions.
PR012..............................  ITRANS................  1 (default)...........  Transitional plume rise is
                                                                                      used.
PR013..............................  TERCOR................  6*0.5 (default).......  Plume patch correction
                                                                                      factors.
PR014..............................  RVPTG.................  0.02, 0.035 (default).  Vertical potential
                                                                                      temperature gradient
                                                                                      values for stabilities E
                                                                                      and F.
PR015..............................  ITIPD.................  1.....................  Stack-tip downwash is used.
PR020..............................  ISHEAR................  0 (default)...........  Wind shear; not used.
PR022..............................  IREFL.................  1 (default)...........  Partial surface reflection
                                                                                      is used.
PR023..............................  IHORIZ................  2 (default)...........  Sector averaging.
                                     SECTOR................  6*22.5 (default)......  Using 22.5 deg. sectors.
PR016 to 019; 021; and 024.........  IY, IZ, IRVPTG,         0.....................  Hourly values of
                                      IHVPTG; IEPS; IEMIS.                            turbulence, vertical
                                                                                      potential temperature
                                                                                      gradient, wind speed
                                                                                      profile exponents, and
                                                                                      stack emissions are not
                                                                                      used.
----------------------------------------------------------------------------------------------------------------

       6.0  Models for Ozone, Carbon Monoxide and Nitrogen Dioxide

                             6.1 Discussion

    a. Models discussed in this section are applicable to pollutants 
often associated with mobile sources, e.g., ozone (O3), 
carbon monoxide (CO) and nitrogen dioxide (NO2). Where 
stationary sources of CO and NO2 are of concern, the reader 
is referred to sections 4 and 5
    b. A control agency with jurisdiction over areas with significant 
ozone problems and which has sufficient resources and data to use a 
photochemical dispersion model is encouraged to do so. Experience with 
and evaluations of the Urban Airshed Model show it to be an acceptable, 
refined approach, and better data bases are becoming available that 
support the more sophisticated analytical procedures. However, empirical 
models (e.g., EKMA) fill the gap between more sophisticated 
photochemical dispersion models and proportional (rollback) modeling 
techniques and may be the only applicable procedure if the available 
data bases are insufficient for refined dispersion modeling.
    c. Models for assessing the impact of carbon monoxide emissions are 
needed for a number of different purposes, e.g., to evaluate the effects 
of point sources, congested intersections and highways, as well as the 
cumulative effect on ambient CO concentrations of all sources of CO in 
an urban area.94 95
    d. Nitrogen oxides are reactive and also an important contribution 
to the photochemical ozone problem. They are usually of most concern in 
areas of high ozone concentrations. Unless suitable photochemical 
dispersion models are used, assumptions regarding the conversion of NO 
to NO2 are required when modeling. Site-specific conversion 
factors may be developed. If site-specific conversion factors are not 
available or photochemical models are not used, NO2 modeling 
should be considered only a screening procedure.

                           6.2 Recommendations

                         6.2.1 Models for Ozone

    a. The Urban Airshed Model (UAM)19 28 is recommended for 
photochemical or reactive pollutant modeling applications involving 
entire urban areas. To ensure proper execution of this numerical model, 
users must satisfy the extensive input data requirements for the model 
as listed in appendix A and the users guide. Users are also referred to 
the ``Guideline for Regulatory Application of the Urban Airshed Model'' 
\29\ for additional data requirements and procedures for operating this 
model.
    b. The empirical model, City-specific EKMA,19 30-33 has 
limited applicability for

[[Page 404]]

urban ozone analyses. Model users should consult the appropriate 
Regional Office on a case-by-case basis concerning acceptability of this 
modeling technique.
    c. Appendix B contains some additional models that may be applied on 
a case-by-case basis for photochemical or reactive pollutant modeling. 
Other photochemical models, including multi-layered trajectory models, 
that are available may be used if shown to be appropriate. Most 
photochemical dispersion models require emission data on individual 
hydrocarbon species and may require three dimensional meteorological 
information on an hourly basis. Reasonably sophisticated computer 
facilities are also often required. Because the input data are not 
universally available and studies to collect such data are very resource 
intensive, there are only limited evaluations of those models.
    d. For those cases which involve estimating the impact on ozone 
concentrations due to stationary sources of VOC and NOX, 
whether for permitting or other regulatory cases, the model user should 
consult the appropriate Regional Office on the acceptability of the 
modeling technique.
    e. Proportional (rollback/forward) modeling is not an acceptable 
procedure for evaluating ozone control strategies.

                    6.2.2 Models for Carbon Monoxide

    a. For analyzing CO impacts at roadway intersections, users should 
follow the procedures in the ``Guideline for Modeling Carbon Monoxide 
from Roadway Intersections''. \34\ The recommended model for such 
analyses is CAL3QHC. \35\ This model combines CALINE3 (already in 
appendix A) with a traffic model to calculate delays and queues that 
occur at signalized intersections. In areas where the use of either 
TEXIN2 or CALINE4 has previously been established, its use may continue. 
The capability exists for these intersection models to be used in either 
a screening or refined mode. The screening approach is described in 
reference 34; a refined approach may be considered on a case-by-case 
basis. The latest version of the MOBILE (mobile source emission factor) 
model should be used for emissions input to intersection models.
    b. For analyses of highways characterized by uninterrupted traffic 
flows, CALINE3 is recommended, with emissions input from the latest 
version of the MOBILE model.
    c. The recommended model for urban areawide CO analyses is RAM or 
Urban Airshed Model (UAM); see appendix A. Information on SIP 
development and requirements for using these models can be found in 
references 34, 96, 97 and 98.
    d. Where point sources of CO are of concern, they should be treated 
using the screening and refined techniques described in section 4 or 5 
of the Guideline.

           6.2.3 Models for Nitrogen Dioxide (Annual Average)

    a. A tiered screening approach is recommended to obtain annual 
average estimates of NO2 from point sources for New Source 
Review analysis, including PSD, and for SIP planning purposes. This 
multi-tiered approach is conceptually shown in Figure 6-1 and described 
in paragraphs b and c of this section. Figure 6-1 is as follows:

   Figure 6-1--Multi-tiered Screening Approach for Estimating Annual 
            NO2 Concentrations From Point Sources

Tier 1: Assume Total Conversion of NO to NO2

                                

Tier 2: Multiply Annual NOX Estimate by Empirically Derived 
NO2/NOX Ratio.

    b. For Tier 1 (the initial screen), use an appropriate Gaussian 
model from appendix A to estimate the maximum annual average 
concentration and assume a total conversion of NO to NO2. If 
the concentration exceeds the NAAQS and/or PSD increments for 
NO2, proceed to the 2nd level screen.
    c. For Tier 2 (2nd level) screening analysis, multiply the Tier 1 
estimate(s) by an empirically derived NO2/NOX 
value of 0.75 (annual national default).36 An annual 
NO2/NOX ratio differing from 0.75 may be used if 
it can be shown that such a ratio is based on data likely to be 
representative of the location(s) where maximum annual impact from the 
individual source under review occurs. In the case where several sources 
contribute to consumption of a PSD increment, a locally derived annual 
NO2/NOX ratio should also be shown to be 
representative of the location where the maximum collective impact from 
the new plus existing sources occurs.
    d. In urban areas, a proportional model may be used as a preliminary 
assessment to evaluate control strategies to meet the NAAQS for multiple 
minor sources, i.e. minor point, area and mobile sources of 
NOX; concentrations resulting from major point sources should 
be estimated separately as discussed above, then added to the impact of 
the minor sources. An acceptable screening technique for urban complexes 
is to assume that all NOX is emitted in the form of 
NO2 and to use a model from appendix A for nonreactive 
pollutants to estimate NO2 concentrations. A more accurate 
estimate can be obtained by: (1) Calculating the annual average 
concentrations of NOX with an urban model, and (2) converting 
these estimates to NO2 concentrations using an empirically 
derived annual NO2/NOX ratio. A value of 0.75 is 
recommended for this ratio. However, a spatially averaged annual 
NO2/NOX ratio may be determined from an existing 
air quality monitoring network and used in lieu of the

[[Page 405]]

0.75 value if it is determined to be representative of prevailing ratios 
in the urban area by the reviewing agency. To ensure use of appropriate 
locally derived annual NO2/NOX ratios, monitoring 
data under consideration should be limited to those collected at 
monitors meeting siting criteria defined in 40 CFR part 58, appendix D 
as representative of ``neighborhood'', ``urban'', or ``regional'' 
scales. Furthermore, the highest annual spatially averaged 
NO2/NOX ratio from the most recent 3 years of 
complete data should be used to foster conservatism in estimated 
impacts.
    e. To demonstrate compliance with NO2 PSD increments in 
urban areas, emissions from major and minor sources should be included 
in the modeling analysis. Point and area source emissions should be 
modeled as discussed above. If mobile source emissions do not contribute 
to localized areas of high ambient NO2 concentrations, they 
should be modeled as area sources. When modeled as area sources, mobile 
source emissions should be assumed uniform over the entire highway link 
and allocated to each area source grid square based on the portion of 
highway link within each grid square. If localized areas of high 
concentrations are likely, then mobile sources should be modeled as line 
sources with the preferred model ISCLT.
    f. More refined techniques to handle special circumstances may be 
considered on a case-by-case basis and agreement with the reviewing 
authority should be obtained. Such techniques should consider individual 
quantities of NO and NO2 emissions, atmospheric transport and 
dispersion, and atmospheric transformation of NO to NO2. 
Where they are available, site-specific data on the conversion of NO to 
NO2 may be used. Photochemical dispersion models, if used for 
other pollutants in the area, may also be applied to the NOX 
problem.

                      7.0 Other Model Requirements

                             7.1 Discussion

    a. This section covers those cases where specific techniques have 
been developed for special regulatory programs. 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. No attempt has been made to provide a comprehensive 
discussion of each topic since the reference documents were designed to 
do that. This section will undergo periodic revision as new programs are 
added and new techniques are developed.
    b. Other Federal agencies have also developed specific modeling 
approaches for their own regulatory or other requirements. An example of 
this is the three-volume manual issued by the U. S. Department of 
Housing and Urban Development, ``Air Quality Considerations in 
Residential Planning.'' \37\ Although such regulatory requirements and 
manuals may 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 manual or 
directive.
    c. The need to estimate impacts at distances greater than 50km (the 
nominal distance to which EPA considers most Gaussian models applicable) 
is an important one especially when considering the effects from 
secondary pollutants. Unfortunately, models submitted to EPA have not as 
yet undergone sufficient field evaluation to be recommended for general 
use. Existing data bases from field studies at mesoscale and long range 
transport distances are limited in detail. This limitation is a result 
of the expense to perform the field studies required to verify and 
improve mesoscale and long range transport models. Particularly 
important and sparse are meteorological data adequate for generating 
three dimensional wind fields. Application of models to complicated 
terrain compounds the difficulty. EPA has completed limited evaluation 
of several long range transport (LRT) models against two sets of field 
data. The evaluation results are discussed in the document, ``Evaluation 
of Short-Term Long-Range Transport Models.'' 99 100 For the 
time being, long range and mesoscale transport models must be evaluated 
for regulatory use on a case-by-case basis.
    d. There are several regulatory programs for which air pathway 
analysis procedures and modeling techniques have been developed. For 
continuous emission releases, ISC forms the basis of many analytical 
techniques. EPA is continuing to evaluate the performance of a number of 
proprietary and public domain models for intermittent and non-stack 
emission releases. Until EPA completes its evaluation, it is premature 
to recommend specific models for air pathway analyses of intermittent 
and non-stack releases in the Guideline.
    e. Regional scale models are used by EPA to develop and evaluate 
national policy and assist State and local control agencies. Two such 
models are the Regional Oxidant Model (ROM) 101 102 103 and 
the Regional Acid Deposition Model (RADM). \104\ Due to the level of 
resources required to apply these models, it is not envisioned that 
regional scale models will be used directly in most model applications.

                           7.2 Recommendations

                 7.2.1 Fugitive Dust/Fugitive Emissions

    a. Fugitive dust usually refers to the dust put into the atmosphere 
by the wind blowing over plowed fields, dirt roads or desert or

[[Page 406]]

sandy areas with little or no vegetation. Reentrained dust is that which 
is put into the air by reason of vehicles driving over dirt roads (or 
dirty roads) and dusty areas. Such sources can be characterized as line, 
area or volume sources. Emission rates may be based on site-specific 
data or values from the general literature.
    b. Fugitive emissions are usually defined as emissions that come 
from an industrial source complex. They 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. 
Where such fugitive emissions can be properly specified, the ISC model, 
with consideration of gravitational settling and dry deposition, is the 
recommended model. In some unique cases a model developed specifically 
for the situation may be needed.
    c. Due to the difficult nature of characterizing and modeling 
fugitive dust and fugitive emissions, it is recommended that the 
proposed procedure be cleared by the appropriate Regional Office for 
each specific situation before the modeling exercise is begun.

                        7.2.2 Particulate Matter

    a. The particulate matter NAAQS, promulgated on July 1, 1987 (52 FR 
24634), includes only particles with an aerodynamic diameter less than 
or equal to a nominal 10 micrometers (PM-10). EPA promulgated 
regulations for PSD increments measured as PM-10 on June 3, 1993 (58 FR 
31621), which are codified at Secs. 51.166(c) and 52.21(c).
    b. Screening techniques like those identified in section 4 are also 
applicable to PM-10 and to large particles. It is recommended that 
subjectively determined values for ``half-life'' or pollutant decay not 
be used as a surrogate for particle removal. Conservative assumptions 
which do not allow removal or transformation are suggested for 
screening. Proportional models (rollback/forward) may not be applied for 
screening analysis, unless such techniques are used in conjunction with 
receptor modeling.
    c. Refined models such as those in section 4.0 are recommended for 
PM-10 and large particles. However, where possible, particle size, gas-
to-particle formation, and their effect on ambient concentrations may be 
considered. For urban-wide refined analyses CDM 2.0 (long term) or RAM 
(short term) should be used. ISC is recommended for point sources of 
small particles and for source-specific analyses of complicated sources. 
No model recommended for general use at this time accounts for secondary 
particulate formation or other transformations in a manner suitable for 
SIP control strategy demonstrations. Where possible, the use of receptor 
models 38 39 105 106 107 in conjunction with dispersion 
models is encouraged to more precisely characterize the emissions 
inventory and to validate source specific impacts calculated by the 
dispersion model. A SIP development guideline,108 model 
reconciliation guidance,106 and an example model application 
109 are available to assist in PM-10 analyses and control 
strategy development.
    d. Under certain conditions, recommended dispersion models are not 
available or applicable. In such circumstances, the modeling approach 
should be approved by the appropriate Regional Office on a case-by-case 
basis. For example, where there is no recommended air quality model and 
area sources are a predominant component of PM-10, an attainment 
demonstration may be based on rollback of the apportionment derived from 
two reconciled receptor models, if the strategy provides a conservative 
demonstration of attainment. At this time, analyses involving model 
calculations for distances beyond 50km and under stagnation conditions 
should also be justified on a case-by-case basis (see sections 7.2.6 and 
8.2.10).
    e. As an aid to assessing the impact on ambient air quality of 
particulate matter generated from prescribed burning activities, 
reference 110 is available.

                               7.2.3 Lead

    a. The air quality analyses required for lead implementation plans 
are given in Secs. 51.83, 51.84 and 51.85. Sections 51.83 and 51.85 
require the use of a modified rollback model as a minimum to demonstrate 
attainment of the lead air quality standard but the use of a dispersion 
model is the preferred approach. Section 51.83 requires the analysis of 
an entire urban area if the measured lead concentration in the urbanized 
area exceeds a quarterly (three month) average of 4.0 g/m\3\. 
Section 51.84 requires the use of a dispersion model to demonstrate 
attainment of the lead air quality standard around specified lead point 
sources. For other areas reporting a violation of the lead standard, 
Sec. 51.85 requires an analysis of the area in the vicinity of the 
monitor reporting the violation. The NAAQS for lead is a quarterly 
(three month) average, thus requiring the use of modeling techniques 
that can provide long-term concentration estimates.
    b. The SIP should contain an air quality analysis to determine the 
maximum quarterly lead concentration resulting from major lead point 
sources, such as smelters, gasoline additive plants, etc. For these 
applications the ISC model is preferred, since the model can account for 
deposition of particles and the impact of fugitive emissions. If the 
source is located in complicated terrain or is subject to unusual 
climatic conditions, a case-specific review by the appropriate Regional 
Office may be required.
    c. In modeling the effect of traditional line sources (such as a 
specific roadway or highway) on lead air quality, dispersion models

[[Page 407]]

applied for other pollutants can be used. Dispersion models such as 
CALINE3 have been widely used for modeling carbon monoxide emissions 
from highways. However, where deposition is of concern, the line source 
treatment in ISC may be used. Also, where there is a point source in the 
middle of a substantial road network, the lead concentrations that 
result from the road network should be treated as background (see 
section 9.2); the point source and any nearby major roadways should be 
modeled separately using the ISC model.
    d. To model an entire major urban area or to model areas without 
significant sources of lead emissions, as a minimum a proportional 
(rollback) model may be used for air quality analysis. The rollback 
philosophy assumes that measured pollutant concentrations are 
proportional to emissions. However, urban or other dispersion models are 
encouraged in these circumstances where the use of such models is 
feasible.
    e. For further information concerning the use of models in the 
development of lead implementation plans, the documents ``Supplementary 
Guidelines for Lead Implementation Plans,'' \40\ and ``Updated 
Information on Approval and Promulgation of Lead Implementation Plans,'' 
\41\ should be consulted.

                            7.2.4. Visibility

    a. The visibility regulations as promulgated in December 1980 
b require consideration of the effect of new sources on the 
visibility values of Federal Class I areas. The state of scientific 
knowledge concerning identifying, monitoring, modeling, and controlling 
visibility impairment is contained in an EPA report ``Protecting 
Visibility: An EPA Report to Congress''.\42\ In 1985, EPA promulgated 
Federal Implementation Plans (FIPs) for States without approved 
visibility provisions in their SIPs. A monitoring plan was established 
as part of the FIPs.c
---------------------------------------------------------------------------

    \b\ Sec. 51.300-307.
    \c\ Sec. 51.300-307.
---------------------------------------------------------------------------

    b. Guidance and a screening model, VISCREEN, is contained in the EPA 
document ``Workbook for Plume Visual Impact Screening and Analysis 
(Revised).'' \43\ VISCREEN can be used to calculate the potential impact 
of a plume of specified emissions for specific transport and dispersion 
conditions. If a more comprehensive analysis is required, any refined 
model should be selected in consultation with the EPA Regional Office 
and the appropriate Federal Land Manager who is responsible for 
determining whether there is an adverse effect by a plume on a Class I 
area.
    c. PLUVUE II, listed in appendix B, may be applied on a case-by-case 
basis when refined plume visibility evaluations are needed. Plume 
visibility models have been evaluated against several data sets.44, 
45

           7.2.5 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 emission 
limitations by Secs. 51.118 and 51.164. The definitions of GEP stack 
height and dispersion technique are contained in Sec. 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 references 46, 47, 48, and 49.
    b. If stacks for new or existing major sources are found to be less 
than the height defined by EPA's refined formula for determining GEP 
height, d then air quality impacts associated with cavity or 
wake effects due to the nearby building structures should be determined. 
Detailed downwash screening procedures \18\ for both the cavity and wake 
regions should be followed. If more refined concentration estimates are 
required, the Industrial Source Complex (ISC) model contains algorithms 
for building wake calculations and should be used. Fluid modeling can 
provide a great deal of additional information for evaluating and 
describing the cavity and wake effects.
---------------------------------------------------------------------------

    \d\ The EPA refined formula height is defined as H + 1.5L (see 
Reference 46).
---------------------------------------------------------------------------

          7.2.6 Long Range Transport (LRT) (i.e., beyond 50km)

    a. Section 165(e) of the Clean Air Act requires that suspected 
significant impacts on PSD Class I areas be determined. However, 50km is 
the useful distance to which most Gaussian models are considered 
accurate for setting emission limits. Since in many cases PSD analyses 
may show that Class I areas may be threatened at distances greater than 
50km from new sources, some procedure is needed to (1) determine if a 
significant impact will occur, and (2) identify the model to be used in 
setting an emission limit if the Class I increments are threatened 
(models for this purpose should be approved for use on a case-by-case 
basis as required in section 3.2). This procedure and the models 
selected for use should be determined in consultation with the EPA 
Regional Office and the appropriate Federal Land Manager (FLM). While 
the ultimate decision on whether a Class I area is adversely affected is 
the responsibility of the permitting authority, the FLM has an 
affirmative responsibility to protect air quality related values that 
may be affected.

[[Page 408]]

    b. If LRT is determined to be important, then estimates utilizing an 
appropriate refined model for receptors at distances greater than 50 km 
should be obtained. MESOPUFF II, listed in appendix B, may be applied on 
a case-by-case basis when LRT estimates are needed. Additional 
information on applying this model is contained in the EPA document ``A 
Modeling Protocol For Applying MESOPUFF II to Long Range Transport 
Problems''. \111\

         7.2.7 Modeling Guidance for Other Governmental Programs

    a. When using the models 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 or 
State agency to ensure the proper application and use of that model. For 
modeling associated with PSD permit applications that involve a Class I 
area, the appropriate Federal Land Manager should be consulted on all 
modeling questions.
    b. The Offshore and Coastal Dispersion (OCD) model \112\ was 
developed by the Minerals Management Service and is recommended for 
estimating air quality impact from offshore sources on onshore, flat 
terrain areas. The OCD model is not recommended for use in air quality 
impact assessments for onshore sources. Sources located on or just 
inland of a shoreline where fumigation is expected should be treated in 
accordance with section 8.2.9.
    c. The Emissions and Dispersion Modeling System (EDMS) \113\ was 
developed by the Federal Aviation Administration and the United States 
Air Force and is recommended for air quality assessment of primary 
pollutant impacts at airports or air bases. Regulatory application of 
EDMS is intended for estimating the cumulative effect of changes in 
aircraft operations, point source, and mobile source emissions on 
pollutant concentrations. It 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 independent of changes in 
aircraft operations. If changes in other than aircraft operations are 
associated with analyses, a model recommended in Chapter 4, 5, or 6 
should be used.

       7.2.8 Air Pathway Analyses (Air Toxics and Hazardous Waste)

    a. Modeling is becoming an increasingly important tool for 
regulatory control agencies to assess the air quality impact of releases 
of toxics and hazardous waste materials. Appropriate screening 
techniques \114\ \115\ for calculating ambient concentrations due to 
various well-defined neutrally buoyant toxic/hazardous pollutant 
releases are available.
    b. Several regulatory programs within EPA have developed modeling 
techniques and guidance for conducting air pathway analyses as noted in 
references 116-129. ISC forms the basis of the modeling procedures for 
air pathway analyses of many of these regulatory programs and, where 
identified, is appropriate for obtaining refined ambient concentration 
estimates of neutrally buoyant continuous air toxic releases from 
traditional sources. Appendix A to the Guideline contains additional 
models appropriate for obtaining refined estimates of continuous air 
toxic releases from traditional sources. Appendix B contains models that 
may be used on a case-by-case basis for obtaining refined estimates of 
denser-than-air intermittent gaseous releases, e.g., DEGADIS; \130\ 
guidance for the use of such models is also available. \131\
    c. Many air toxics models require input of chemical properties and/
or chemical engineering variables in order to appropriately characterize 
the source emissions prior to dispersion in the atmosphere; reference 
132 is one source of helpful data. In addition, EPA has numerous 
programs to determine emission factors and other estimates of air toxic 
emissions. The Regional Office should be consulted for guidance on 
appropriate emission estimating procedures and any uncertainties that 
may be associated with them.

                   8.0 General Modeling Considerations

                             8.1 Discussion

    a. This section contains recommendations concerning a number of 
different issues not explicitly covered in other sections of this guide. 
The topics covered here are not specific to any one program or modeling 
area but are common to nearly all modeling analyses.

                           8.2 Recommendations

                       8.2.1 Design Concentrations

8.2.1.1 Design Concentrations for Criteria Pollutants With Deterministic 
                                Standards

    a. An air quality analysis for SO2, CO, Pb, and 
NO2 is required to determine if the source will (1) Cause a 
violation of the NAAQS, or (2) cause or contribute to air quality 
deterioration greater than the specified allowable PSD increment. For 
the former, background concentration (see section 9.2) should be added 
to the estimated impact of the source to determine the design 
concentration. For the latter, the design concentration includes impact 
from all increment consuming sources.
    b. If the air quality analyses are conducted using the period of 
meteorological input data recommended in section 9.3.1.2 (e.g., 5 years 
of NWS data or 1 year of site-specific data), then the design 
concentration based on the

[[Page 409]]

highest, second-highest short term concentration or long term average, 
whichever is controlling, should be used to determine emission 
limitations to assess compliance with the NAAQS and to determine PSD 
increments.
    c. When sufficient and representative data exist for less than a 5-
year period from a nearby NWS site, or when on-site data have been 
collected for less than a full continuous year, or when it has been 
determined that the on site data may not be temporally representative, 
then the highest concentration estimate should be considered the design 
value. This is because the length of the data record may be too short to 
assure that the conditions producing worst-case estimates have been 
adequately sampled. The highest value is then a surrogate for the 
concentration that is not to be exceeded more than once per year (the 
wording of the deterministic standards). Also, the highest concentration 
should be used whenever selected worst-case conditions are input to a 
screening technique. This specifically applies to the use of techniques 
such as outlined in ``Screening Procedures for Estimating the Air 
Quality Impact of Stationary Sources, Revised''. \18\ Specific guidance 
for CO may be found in the ``Guideline for Modeling Carbon Monoxide from 
Roadway Intersections''. \34\
    d. If the controlling concentration is an annual average value and 
multiple years of data (on-site or NWS) are used, then the design value 
is the highest of the annual averages calculated for the individual 
years. If the controlling concentration is a quarterly average and 
multiple years are used, then the highest individual quarterly average 
should be considered the design value.
    e. As long a period of record as possible should be used in making 
estimates to determine design values and PSD increments. If more than 1 
year of site-specific data is available, it should be used.

  8.2.1.2 Design Concentrations for Criteria Pollutants With Expected 
                          Exceedance Standards

    a. Specific instructions for the determination of design 
concentrations for criteria pollutants with expected exceedance 
standards, ozone and PM-10, are contained in special guidance documents 
for the preparation of SIPs for those pollutants. \86\ \108\ For all SIP 
revisions the user should check with the Regional Office to obtain the 
most recent guidance documents and policy memoranda concerning the 
pollutant in question.

                      8.2.2 Critical Receptor Sites

    a. Receptor sites for refined modeling should be utilized in 
sufficient detail to estimate the highest concentrations and possible 
violations of a NAAQS or a PSD increment. In designing a receptor 
network, the emphasis should be placed on receptor resolution and 
location, not total number of receptors. The selection of receptor sites 
should be a case-by-case determination taking into consideration the 
topography, the climatology, monitor sites, and the results of the 
initialscreening procedure. For large sources (those equivalent to a 
500MW power plant) and where violations of the NAAQS or PSD increment 
are likely, 360 receptors for a polar coordinate grid system and 400 
receptors for a rectangular grid system, where the distance from the 
source to the farthest receptor is 10km, are usually adequate to 
identify areas of high concentration. Additional receptors may be needed 
in the high concentration location if greater resolution is indicated by 
terrain or source factors.

                      8.2.3 Dispersion Coefficients

    a. Gaussian models used in most applications should employ 
dispersion coefficients consistent with those contained in the preferred 
models in appendix A. Factors such as averaging time, urban/rural 
surroundings, and type of source (point vs. line) may dictate the 
selection of specific coefficients. Generally, coefficients used in 
appendix A models are identical to, or at least based on, Pasquill-
Gifford coefficients \50\ in rural areas and McElroy-Pooler \51\ 
coefficients in urban areas.
    b. Research is continuing toward the development of methods to 
determine dispersion coefficients directly from measured or observed 
variables. \52\ \53\ No method to date has proved to be widely 
applicable. Thus, direct measurement, as well as other dispersion 
coefficients related to distance and stability, may be used in Gaussian 
modeling only if a demonstration can be made that such parameters are 
more applicable and accurate for the given situation than are algorithms 
contained in the preferred models.
    c. Buoyancy-induced dispersion (BID), as identified by Pasquill, 
\54\ is included in the preferred models and should be used where 
buoyant sources, e.g., those involving fuel combustion, are involved.

                       8.2.4 Stability Categories

    a. The Pasquill approach to classifying stability is generally 
required in all preferred models (Appendix A). The Pasquill method, as 
modified by Turner, \55\ was developed for use with commonly observed 
meteorological data from the National Weather Service and is based on 
cloud cover, insolation and wind speed.
    b. Procedures to determine Pasquill stability categories from other 
than NWS data are found in subsection 9.3. Any other method to determine 
Pasquill stability categories must be justified on a case-by-case basis.
    c. For a given model application where stability categories are the 
basis for selecting

[[Page 410]]

dispersion coefficients, both y and 
z should be determined from the same stability 
category. ``Split sigmas'' in that instance are not recommended.
    d. Sector averaging, which eliminates the y 
term, is generally acceptable only to determine long term averages, such 
as seasonal or annual, and when the meteorological input data are 
statistically summarized as in the STAR summaries. Sector averaging is, 
however, commonly acceptable in complex terrain screening methods.

                            8.2.5 Plume Rise

    a. The plume rise methods of Briggs \56\ \57\ are incorporated in 
the preferred models and are recommended for use in all modeling 
applications. No provisions in these models are made for fumigation or 
multistack plume rise enhancement or the handling of such special plumes 
as flares; these problems should be considered on a case-by-case basis.
    b. Since there is insufficient information to identify and quantify 
dispersion during the transitional plume rise period, gradual plume rise 
is not generally recommended for use. There are two exceptions where the 
use of gradual plume rise is appropriate: (1) In complex terrain 
screening procedures to determine close-in impacts; (2) when calculating 
the effects of building wakes. The building wake algorithm in the ISC 
model incorporates and automatically (i.e., internally) exercises the 
gradual plume rise calculations. 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.
    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 (Hanna et al.) \57\ is the 
recommended technique for this situation and is found in the point 
source preferred models.
    d. Where aerodynamic downwash occurs due to the adverse influence of 
nearby structures, the algorithms included in the ISC model 
58 should be used.

                      8.2.6 Chemical Transformation

    a. The chemical transformation of SO2 emitted from point 
sources or single industrial plants in rural areas is generally assumed 
to be relatively unimportant to the estimation of maximum concentrations 
when travel time is limited to a few hours. However, in urban areas, 
where synergistic effects among pollutants are of considerable 
consequence, chemical transformation rates may be of concern. In urban 
area applications, a half-life of 4 hours \55\ may be applied to the 
analysis of SO2 emissions. Calculations of transformation 
coefficients from site-specific studies can be used to define a ``half-
life'' to be used in a Gaussian model with any travel time, or in any 
application, if appropriate documentation is provided. Such conversion 
factors for pollutant half-life should not be used with screening 
analyses.
    b. Complete conversion of NO to NO2 should be assumed for 
all travel time when simple screening techniques are used to model point 
source emissions of nitrogen oxides. If a Gaussian model is used, and 
data are available on seasonal variations in maximum ozone 
concentrations, the Ozone Limiting Method \36\ is recommended. In 
refined analyses, case-by case conversion rates based on technical 
studies appropriate to the site in question may be used. The use of more 
sophisticated modeling techniques should be justified for individual 
cases.
    c. Use of models incorporating complex chemical mechanisms should be 
considered only on a case-by-case basis with proper demonstration of 
applicability. These are generally regional models not designed for the 
evaluation of individual sources but used primarily for region-wide 
evaluations. Visibility models also incorporate chemical transformation 
mechanisms which are an integral part of the visibility model itself and 
should be used in visibility assessments.

               8.2.7 Gravitational Settling and Deposition

    a. An ``infinite half-life'' should be used for estimates of 
particle concentrations when Gaussian models containing only exponential 
decay terms for treating settling and deposition are used.
    b. Gravitational settling and deposition may be directly included in 
a model if either is a significant factor. One preferred model (ISC) 
contains a settling and deposition algorithm and is recommended for use 
when particulate matter sources can be quantified and settling and 
deposition are problems.

                    8.2.8 Urban/Rural Classification

    a. The selection of either rural or urban dispersion coefficients in 
a specific application should follow one of the procedures suggested by 
Irwin \59\ and briefly described below. These include a land use 
classification procedure or a population based procedure to determine 
whether the character of an area is primarily urban or rural.
    b. Land Use Procedure: (1) Classify the land use within the total 
area, Ao, circumscribed by a 3km radius circle about the 
source using the meteorological land use typing scheme proposed by Auer 
\60\; (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.
    c. Population Density Procedure: (1) Compute the average population 
density, p per

[[Page 411]]

square kilometer with Ao as defined above; (2) If p is 
greater than 750 people/km\2\, use urban dispersion coefficients; 
otherwise use appropriate rural dispersion coefficients.
    d. Of the two methods, the land use procedure is considered more 
definitive. Population density should be used with caution and should 
not be applied to highly industrialized areas where the population 
density may be low and thus a rural classification would be indicated, 
but the area is sufficiently built-up so that the urban land use 
criteria would be satisfied. In this case, the classification should 
already be ``urban'' and urban dispersion parameters should be used.
    e. Sources located in an area defined as urban should be modeled 
using urban dispersion parameters. Sources located in areas defined as 
rural should be modeled using the rural dispersion parameters. 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.

                            8.2.9 Fumigation

    a. 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 either 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 procedures (see 
``Screening Procedures for Estimating the Air Quality Impact of 
Stationary Sources'' \18\) that may be used to approximate the 
concentrations. Considerable care should be exercised in using the 
results obtained from the screening techniques.
    b. Fumigation is also 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 Shoreline Dispersion Model (SDM) listed in appendix B may 
be applied on a case-by-case basis when air quality estimates under 
shoreline fumigation conditions are needed.\133\ Information on the 
results of EPA's evaluation of this model together with other coastal 
fumigation models may be found in reference 134. Selection of the 
appropriate model for applications where shoreline fumigation is of 
concern should be determined in consultation with the Regional Office.

                            8.2.10 Stagnation

    a. 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.
    b. When stagnation periods such as these are found to occur, they 
should be addressed in the air quality modeling analysis. WYNDvalley, 
listed in appendix B, may be applied on a case-by-case basis for 
stagnation periods of 24 hours or longer in valley-type situations. 
Caution should be exercised when applying the model to elevated point 
sources. Users should consult with the appropriate Regional Office prior 
to regulatory application of WYNDvalley.

                      8.2.11 Calibration of Models

    a. Calibration of long term multi-source models has been a widely 
used procedure even though the limitations imposed by statistical theory 
on the reliability of the calibration process for long term estimates 
are well known. \61\ In some cases, where a more accurate model is not 
available, calibration may be the best alternative for improving the 
accuracy of the estimated concentrations needed for control strategy 
evaluations.
    b. Calibration of short term models is not common practice and is 
subject to much greater error and misunderstanding. There have been 
attempts by some to compare short term estimates and measurements on an 
event-by-event basis and then to calibrate a model with results of that 
comparison. This approach is severely limited by uncertainties in both 
source and meteorological data and therefore it is difficult to 
precisely estimate the concentration at an exact location for a specific 
increment of time. Such uncertainties make calibration of short term 
models of questionable benefit. Therefore, short term model calibration 
is unacceptable.

                          9.0 Model Input Data

    a. Data bases and related procedures for estimating input parameters 
are an integral part of the modeling procedure. The most appropriate 
data available should always be selected for use in modeling analyses. 
Concentrations can vary widely depending on the source data or 
meteorological data used. Input data are a major source of 
inconsistencies in any modeling analysis. This section attempts to 
minimize the uncertainty associated with data base selection and use by 
identifying requirements for data used in

[[Page 412]]

modeling. A checklist of input data requirements for modeling analyses 
is included as appendix C. More specific data requirements and the 
format required for the individual models are described in detail in the 
users' guide for each model.

                             9.1 Source Data

                            9.1.1 Discussion

    a. Sources of pollutants can be classified as point, line and area/
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, but they may 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.
    b. Emission factors are compiled in an EPA publication commonly 
known as AP-42 \62\; an indication of the quality and amount of data on 
which many of the factors are based is also provided. Other information 
concerning emissions is available in EPA publications relating to 
specific source categories. The Regional Office 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.

                          9.1.2 Recommendations

    a. For point source applications the load or operating condition 
that causes maximum ground-level concentrations should 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 standards or PSD 
increments, this load e 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. 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. For a power plant, the following 
paragraphs b through h of this section describe the typical kind of data 
on source characteristics and operating conditions that may be needed. 
Generally, input data requirements for air quality models necessitate 
the use of metric units; where English units are common for engineering 
usage, a conversion to metric is required.
---------------------------------------------------------------------------

    \e\ 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.
---------------------------------------------------------------------------

    b. Plant layout. The connection scheme between boilers and stacks, 
and the distance and direction between stacks, building parameters 
(length, width, height, location and orientation relative to stacks) for 
plant structures which house boilers, control equipment, and surrounding 
buildings within a distance of approximately five stack heights.
    c. Stack parameters. For all stacks, the stack height and inside 
diameter (meters), and the temperature (K) and volume flow rate (actual 
cubic meters per second) or exit gas velocity (meters per second) for 
operation at 100 percent, 75 percent and 50 percent load.
    d. Boiler size. For all boilers, the associated megawatts, 10\6\ 
BTU/hr, and pounds of steam per hour, and the design and/or actual fuel 
consumption rate for 100 percent load for coal (tons/hour), oil 
(barrels/hour), and natural gas (thousand cubic feet/hour).
    e. Boiler parameters. For all boilers, the percent excess air used, 
the boiler type (e.g., wet bottom, cyclone, etc.), and the type of 
firing (e.g., pulverized coal, front firing, etc.).
    f. Operating conditions. For all boilers, the type, amount and 
pollutant contents of fuel, the total hours of boiler operation and the 
boiler capacity factor during the year, and the percent load for peak 
conditions.
    g. Pollution control equipment parameters. For each boiler served 
and each pollutant affected, the type of emission control equipment, the 
year of its installation, its design efficiency and mass emission rate, 
the data of the last test and the tested efficiency, the number of hours 
of operation during the latest year, and the best engineering estimate 
of its projected efficiency if used in conjunction with coal combustion; 
data for any anticipated modifications or additions.
    h. Data for new boilers or stacks. For all new boilers and stacks 
under construction and for all planned modifications to existing boilers 
or stacks, the scheduled date of completion, and the data or best 
estimates available for paragraphs b through g of this section above 
following completion of construction or modification.
    i. In stationary point source applications for compliance with short 
term ambient

[[Page 413]]

standards, SIP control strategies should be tested using the emission 
input shown on table 9-1. When using a refined model, sources should be 
modeled sequentially with these loads for every hour of the year. To 
evaluate SIPs for compliance with quarterly and annual standards, 
emission input data shown in table 9-1 should again be used. Emissions 
from area sources should generally be based on annual average 
conditions. The source input information in each model user's guide 
should be carefully consulted and the checklist in appendix C should 
also be consulted for other possible emission data that could be 
helpful. PSD NAAQS compliance demonstrations should follow the emission 
input data shown in table 9-2. For purposes of emissions trading, new 
source review and demonstrations, refer to current EPA policy and 
guidance to establish input data.
    j. Line source modeling of streets and highways requires data on the 
width of the roadway and the median strip, the types and amounts of 
pollutant emissions, the number of lanes, the emissions from each lane 
and the height of emissions. The location of the ends of the straight 
roadway segments should be specified by appropriate grid coordinates. 
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.
    k. The impact of growth on emissions should be considered in all 
modeling analyses covering existing sources. Increases in emissions due 
to planned expansion or planned fuel switches should be identified. 
Increases in emissions at individual sources that may be associated with 
a general industrial/commercial/residential expansion in multi-source 
urban areas should also be treated. For new sources the impact of growth 
on emissions should generally be considered for the period prior to the 
start-up date for the source. Such changes in emissions should treat 
increased area source emissions, changes in existing point source 
emissions which were not subject to preconstruction review, and 
emissions due to sources with permits to construct that have not yet 
started operation.

                           Table 9-1-- Model Emission Input Data for Point Sources \1\
----------------------------------------------------------------------------------------------------------------
                                   Emission limit (/
        Averaging time                MMBtu) \2\         x   Operating level (MMBtu/  x      Operating factor
                                                                     hr) \2\               (e.g., hr/yr, hr/day)
----------------------------------------------------------------------------------------------------------------
  Stationary Point Source(s) Subject to SIP Emission Limit(s) Evaluation for Compliance with Ambient Standards
                                       (Including Areawide Demonstrations)
----------------------------------------------------------------------------------------------------------------
 
Annual & quarterly............  Maximum allowable            Actual or design             Actual operating
                                 emission limit or            capacity (whichever          factor averaged over
                                 federally enforceable        is greater), or              most recent 2
                                 permit limit.                federally enforceable        years.\3\
                                                              permit condition.
Short term....................  Maximum allowable            Actual or design             Continuous operation,
                                 emission limit or            capacity (whichever          i.e., all hours of
                                 federally enforceable        is greater), or              each time period
                                 permit limit.                federally enforceable        under consideration
                                                              permit condition \4\.        (for all hours of the
                                                                                           meteorological data
                                                                                           base).\5\
----------------------------------------------------------------------------------------------------------------
          Nearby Background Source(s)--Same input requirements as for stationary point source(s) above.
----------------------------------------------------------------------------------------------------------------
 
     Other Background Source(s)--If modeled (see section 9.2.3), input data requirements are defined below.
----------------------------------------------------------------------------------------------------------------
 
Annual & quarterly............  Maximum allowable            Annual level when            Actual operating
                                 emission limit or            actually operating,          factor averaged over
                                 Federal enforceable          averaged over the            the most recent 2
                                 permit limit.                most recent 2 years          years.\3\
                                                              \3\.
Short term....................  Maximum allowable            Annual level when            Continuous operation,
                                 emission limit or            actually operating,          i.e., all hours of
                                 federally enforceable        averaged over the            each time period
                                 permit limit.                most recent 2 years          under consideration
                                                              \3\.                         (for all hours of the
                                                                                           meteorological data
                                                                                           base).\5\
----------------------------------------------------------------------------------------------------------------
\1\ The model input data requirements shown on this table apply to stationary source control strategies for
  STATE IMPLEMENTATION PLANS. For purposes of emissions trading, new source review, or prevention of significant
  deterioration, other model input criteria may apply. Refer to the policy and guidance for these programs to
  establish the input data.
\2\ Terminology applicable to fuel burning sources; analogous terminology (e.g., /throughput) may be used for
  other types of sources.
\3\ Unless it is determined that this period is not representative.
\4\ Operating levels such as 50 percent and 75 percent of capacity should also be modeled to determine the load
  causing the highest concentration.
\5\ If operation does not occur for all hours of the time period of consideration (e.g., 3 or 24 hours) and the
  source operation is constrained by a federally enforceable permit condition, an appropriate adjustment to the
  modeled emission rate may be made (e.g., if operation is only 8:00 a.m. to 4:00 p.m. each day, only these
  hours will be modeled with emissions from the source. Modeled emissions should not be averaged across non-
  operating time periods.)


[[Page 414]]


          Table 9-2--Point Source Model Input Data (Emissions) for PSD NAAQS Compliance Demonstrations
----------------------------------------------------------------------------------------------------------------
                                   Emission limit (/
        Averaging time                MMBtu) \1\         x   Operating level (MMBtu/  x      Operating factor
                                                                     hr) \1\               (e.g., hr/yr, hr/day)
----------------------------------------------------------------------------------------------------------------
                                      Proposed Major New or Modified Source
ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
 
Annual & quarterly............  Maximum allowable            Design capacity or           Continuous operation
                                 emission limit or            federally enforceable        (i.e., 8760
                                 federally enforceable        permit condition.            hours).\2\
                                 permit limit.
Short term ( 24 hours)........  Maximum allowable            Design capacity or           Continuous operation
                                 emission limit or            federally enforceable        (i.e., all hours of
                                 federally enforceable        permit condition.\3\         each time period
                                 permit limit.                                             under consideration)
                                                                                           (for all hours of the
                                                                                           meteorological data
                                                                                           base).\2\
ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
 
                                         Nearby Background Source(s) \4\
ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
 
Annual & quarterly............  Maximum allowable            Actual or design             Actual operating
                                 emission limit or            capacity (whichever          factor averaged over
                                 federally enforceable        is greater), or              the most recent 2
                                 permit limit.                federally enforceable        years.5 7
                                                              permit condition.
Short term ( 24 hours)........  Maximum allowable            Actual or design             Continuous operation
                                 emission limit or            capacity (whichever          (i.e., all hours of
                                 federally enforceable        is greater), or              each time period
                                 permit limit.                federally enforceable        under consideration)
                                                              permit condition.\3\         (for all hours of the
                                                                                           meteorological data
                                                                                           base).\2\
ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
 
                                         Other Background Source(s) \6\
ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½
 
Annual & quarterly............  Maximum allowable            Annual level when            Actual operating
                                 emission limit or            actually operating,          factor averaged over
                                 federally enforceable        averaged over the            the most recent 2
                                 permit limit.                most recent 2                years.5 7
                                                              years.\5\
Short term ( 24 hours)........  Maximum allowable            Annual level when            Continuous operation
                                 emission limit or            actually operating,          (i.e., all hours of
                                 federally enforceable        averaged over the            each time period
                                 permit limit.                most recent 2                under consideration)
                                                              years.\5\                    (for all hours of the
                                                                                           meteorological data
                                                                                           base).\2\
----------------------------------------------------------------------------------------------------------------
\1\ Terminology applicable to fuel burning sources; analogous terminology (e.g., /throughput) may be used for
  other types of sources.
\2\hnsp;If operation does not occur for all hours of the time period of consideration (e.g., 3 or 24 hours) and
  the source operation is constrained by a federally enforceable permit condition, an appropriate adjustment to
  the modeled emission rate may be made (e.g., if operation is only 8:00 a.m. to 4:00 p.m. each day, only these
  hours will be modeled with emissions from the source. Modeled emissions should not be averaged across non-
  operating time periods.
\3\ Operating levels such as 50 percent and 75 percent of capacity should also be modeled to determine the load
  causing the highest concentration.
\4\ Includes existing facility to which modification is proposed if the emissions from the existing facility
  will not be affected by the modification. Otherwise use the same parameters as for major modification.
\5\ Unless it is determined that this period is not representative.
\6\ Generally, the ambient impacts from non-nearby background sources can be represented by air quality data
  unless adequate data do not exist.
\7\ For those permitted sources not yet in operation or that have not established an appropriate factor,
  continuous operation (i.e., 8760 hours) should be used.

                      9.2 Background Concentrations

                            9.2.1 Discussion

    a. Background concentrations are an essential part of the total air 
quality concentration to be considered in determining source impacts. 
Background air quality includes pollutant concentrations due to: (1) 
natural sources; (2) nearby sources other than the one(s) currently 
under consideration; and (3) unidentified sources.
    b. Typically, air quality data should be used to establish 
background concentrations in the vicinity of the source(s) under 
consideration. The monitoring network used for background determinations 
should conform to the same quality assurance and other requirements as 
those networks established for PSD purposes. \63\ An appropriate data 
validation procedure should be applied to the data prior to use.
    c. If the source is not isolated, it may be necessary to use a 
multi-source model to establish the impact of nearby sources. Background 
concentrations should be determined for each critical (concentration) 
averaging time.

[[Page 415]]

             9.2.2 Recommendations (Isolated Single Source)

    a. Two options (paragraph b or c of this section) are available to 
determine the background concentration near isolated sources.
    b. Use air quality data collected in the vicinity of the source to 
determine the background concentration for the averaging times of 
concern.f Determine the mean background concentration at each 
monitor by excluding values when the source in question is impacting the 
monitor. The mean annual background is the average of the annual 
concentrations so determined at each monitor. For shorter averaging 
periods, the meteorological conditions accompanying the concentrations 
of concern should be identified. Concentrations for meteorological 
conditions of concern, at monitors not impacted by the source in 
question, should be averaged for each separate averaging time to 
determine the average background value. Monitoring sites inside a 
90 deg. sector downwind of the source may be used to determine the area 
of impact. One hour concentrations may be added and averaged to 
determine longer averaging periods.
---------------------------------------------------------------------------

    \f\ For purposes of PSD, the location of monitors as well as data 
quality assurance procedures must satisfy requirements listed in the PSD 
Monitoring Guidelines. \63\
---------------------------------------------------------------------------

    c. If there are no monitors located in the vicinity of the source, a 
``regional site'' may be used to determine background. A ``regional 
site'' is one that is located away from the area of interest but is 
impacted by similar natural and distant man-made sources.

               9.2.3 Recommendations (Multi-Source Areas)

    a. In multi-source areas, two components of background should be 
determined.
    b. Nearby Sources: All sources expected to cause a significant 
concentration gradient in the vicinity of the source or sources under 
consideration for emission limit(s) should be explicitly modeled. For 
evaluation for compliance with the short term and annual ambient 
standards, the nearby sources should be modeled using the emission input 
data shown in table 9-1 or 9-2. The number of such sources is expected 
to be small except in unusual situations. The nearby source inventory 
should be determined in consultation with the reviewing authority. It is 
envisioned that the nearby sources and the sources under consideration 
will be evaluated together using an appropriate appendix A model.
    c. The impact of the nearby sources should be examined at locations 
where interactions between the plume of the point source under 
consideration and those of nearby sources (plus natural background) can 
occur. Significant locations 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. These 
locations may be identified through trial and error analyses.
    d. Other Sources: That portion of the background attributable to all 
other sources (e.g., natural sources, minor sources and distant major 
sources) should be determined by the procedures found in section 9.2.2 
or by application of a model using table 9-1 or 9-2.

                      9.3 Meteorological Input Data

    a. 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 data is dependent on: (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.
    b. Model input data are normally obtained either from the National 
Weather Service or as part of an on-site measurement program. Local 
universities, Federal Aviation Administration (FAA), military stations, 
industry and pollution control agencies may also be sources of such 
data. Some recommendations for the use of each type of data are included 
in this section 9.3.

              9.3.1 Length of Record of Meteorological Data

                           9.3.1.1 Discussion

    a. The model user should acquire enough meteorological data to 
ensure that worst-case meteorological conditions are adequately 
represented in the model results. The trend toward statistically based 
standards suggests a need for all meteorological conditions to be 
adequately represented in the data set selected for model input. The 
number of years of record needed to obtain a stable distribution of 
conditions depends on the variable being measured and has been estimated 
by Landsberg and Jacobs \64\ for various parameters. Although that study 
indicates in excess of 10 years may be required to achieve stability in 
the frequency distributions of some meteorological variables, such long 
periods are not reasonable for model input data. This is due in part to 
the fact that hourly data in model input format are

[[Page 416]]

frequently not available for such periods and that hourly calculations 
of concentration for long periods are prohibitively expensive. A recent 
study \65\ compared various periods from a 17-year data set to determine 
the minimum number of years of data needed to approximate the 
concentrations modeled with a 17-year period of meteorological data from 
one station. This study indicated that the variability of model 
estimates due to the meteorological data input was adequately reduced if 
a 5-year period of record of meteorological input was used.

                         9.3.1.2 Recommendations

    a. Five years of representative meteorological data should be used 
when estimating concentrations with an air quality model. Consecutive 
years from the most recent, readily available 5-year period are 
preferred. The meteorological data may be data collected either onsite 
or at the nearest National Weather Service (NWS) station. If the source 
is large, e.g., a 500MW power plant, the use of 5 years of NWS 
meteorological data or at least 1 year of site-specific data is 
required.
    b. If one year or more, up to five years, of site-specific data is 
available, these data are preferred for use in air quality analyses. 
Such data should have been subjected to quality assurance procedures as 
described in section 9.3.3.2.
    c. For permitted sources whose emission limitations are based on a 
specific year of meteorological data that year should be added to any 
longer period being used (e.g., 5 years of NWS data) when modeling the 
facility at a later time.

                   9.3.2 National Weather Service Data

                           9.3.2.1 Discussion

    a. The National Weather Service (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. Direct 
measurements of model input parameters have been made for limited model 
studies and those methods and techniques are becoming more widely 
applied; however, most model applications still rely heavily on the NWS 
data.
    b. There are two standard formats of the NWS data for use in air 
quality models. The short term models use the standard hourly weather 
observations available from the National Climatic Data Center (NCDC). 
These observations are then ``preprocessed'' before they can be used in 
the models. ``STAR'' summaries are available from NCDC for long term 
model use. These are joint frequency distributions of wind speed, 
direction and P-G stability category. They are used as direct input to 
models such as the long term version of ISC. \58\

                         9.3.2.2 Recommendations

    a. The preferred short term models listed in appendix A all accept 
as input the NWS meteorological data preprocessed into model compatible 
form. Long-term (monthly seasonal or annual) preferred models use NWS 
``STAR'' summaries. Summarized concentration estimates from the short 
term models may also be used to develop long-term averages; however, 
concentration estimates based on the two separate input data sets may 
not necessarily agree.
    b. Although most NWS measurements are made at a standard height of 
10 meters, the actual anemometer height should be used as input to the 
preferred model.
    c. National Weather Service wind directions are reported to the 
nearest 10 degrees. A specific set of randomly generated numbers has 
been developed for use with the preferred EPA models and should be used 
to ensure a lack of bias in wind direction assignments within the 
models.
    d. Data from universities, FAA, military stations, industry and 
pollution control agencies may be used if such data are equivalent in 
accuracy and detail to the NWS data.

                        9.3.3 Site-Specific Data

                           9.3.3.1 Discussion

    a. Spatial or geographical representativeness is best achieved by 
collection of all of the needed model input data at the actual site of 
the source(s). Site-specific measured data are therefore preferred as 
model input, provided appropriate instrumentation and quality assurance 
procedures are followed and that the data collected are representative 
(free from undue local or ``micro'' influences) and compatible with the 
input requirements of the model to be used. However, direct measurements 
of all the needed model input parameters may not be possible. This 
section discusses suggestions for the collection and use of on-site 
data. Since the methods outlined in this section are still being tested, 
comparison of the model parameters derived using these site-specific 
data should be compared at least on a spot-check basis, with parameters 
derived from more conventional observations.

         9.3.3.2 Recommendations: Site-specific Data Collection

    a. The document ``On-Site Meteorological Program Guidance for 
Regulatory Modeling Applications'' \66\ provides recommendations

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on the collection and use of on-site meteorological data. 
Recommendations on characteristics, siting, and exposure of 
meteorological instruments and on data recording, processing, 
completeness requirements, reporting, and archiving are also included. 
This publication should be used as a supplement to the limited guidance 
on these subjects now found in the ``Ambient Monitoring Guidelines for 
Prevention of Significant Deterioration''. \63\ Detailed information on 
quality assurance is provided in the ``Quality Assurance Handbook for 
Air Pollution Measurement Systems: Volume IV''. \67\ As a minimum, site-
specific measurements of ambient air temperature, transport wind speed 
and direction, and the parameters to determine Pasquill-Gifford (P-G) 
stability categories should be available in meteorological data sets to 
be used in modeling. Care should be taken to ensure that meteorological 
instruments are located to provide representative characterization of 
pollutant transport between sources and receptors of interest. The 
Regional Office will determine the appropriateness of the measurement 
locations.
    b. All site-specific data should be reduced to hourly averages. 
Table 9-3 lists the wind related parameters and the averaging time 
requirements.
    c. Solar Radiation Measurements. Total solar radiation should be 
measured with a reliable pyranometer, sited and operated in accordance 
with established on-site meteorological guidance. \66\
    d. Temperature Measurements. Temperature measurements should be made 
at standard shelter height (2m) in accordance with established on-site 
meteorological guidance. \66\
    e. Temperature Difference Measurements. Temperature difference 
(all) measurements for use in estimating P-G 
stability categories using the solar radiation/delta-T (SRDT) 
methodology (see Stability Categories) should be obtained using two 
matched thermometers or a reliable thermocouple system to achieve 
adequate accuracy.
    f. Siting, probe placement, and operation of T systems 
should be based on guidance found in Chapter 3 of reference 66, and such 
guidance should be followed when obtaining vertical temperature gradient 
data for use in plume rise estimates or in determining the critical 
dividing streamline height.
    g. Wind Measurements. For refined modeling applications in simple 
terrain situations, if a source has a stack below 100m, select the stack 
top height as the wind measurement height for characterization of plume 
dilution and transport. For sources with stacks extending above 100m, a 
100m tower is suggested unless the stack top is significantly above 100m 
(i.e., 200m). In cases with stack tops 200m, 
remote sensing may be a feasible alternative. In some cases, collection 
of stack top wind speed may be impractical or incompatible with the 
input requirements of the model to be used. In such cases, the Regional 
Office should be consulted to determine the appropriate measurement 
height.
    h. For refined modeling applications in complex terrain, multiple 
level (typically three or more) measurements of wind speed and 
direction, temperature and turbulence (wind fluctuation statistics) are 
required. 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 if the 
representative plume height(s) of interest exceed 100m. The 
meteorological tower need not exceed the lesser of the representative 
plume height of interest (the highest plume height if there is more than 
one plume height of interest) or 100m.
    i. In general, the wind speed used in determining plume rise is 
defined as the wind speed at stack top.
    j. Specifications for wind measuring instruments and systems are 
contained in the ``On-Site Meteorological Program Guidance for 
Regulatory Modeling Applications''. \66\
    k. Stability Categories. 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 10m. The insolation rate is typically assessed using 
observations of cloud cover and ceiling height based on criteria 
outlined by Turner. \50\ It is recommended that the P-G stability 
category be estimated using the Turner method with site-specific wind 
speed measured at or near 10m 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 66. In the absence of requisite data to 
implement the Turner method, the SRDT method or wind fluctuation 
statistics (i.e., the E and A 
methods) may be used.
    l. The SRDT method, described in section 6.4.4.2 of reference 66, is 
modified slightly from that published by Bowen et al. (1983) \136\ and 
has been evaluated with three on-site data bases. \137\ The two methods 
of stability classification which use wind fluctuation

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statistics, the E and A methods, 
are also described in detail in section 6.4.4 of reference 66 (note 
applicable tables in section 6). For additional information on the wind 
fluctuation methods, see references 68-72.
    m. Hours in the record having missing data should be treated 
according to an established data substitution protocol and after valid 
data retrieval requirements have been met. Such protocols are usually 
part of the approved monitoring program plan. Data substitution guidance 
is provided in section 5.3 of reference 66.
    n. Meteorological Data Processors. The following meteorological 
preprocessors are recommended by EPA: RAMMET, PCRAMMET, STAR, PCSTAR, 
MPRM, \135\ and METPRO. \24\ RAMMET is the recommended meteorological 
preprocessor for use in applications employing hourly NWS data. The 
RAMMET format is the standard data input format used in sequential 
Gaussian models recommended by EPA. PCRAMMET \138\ is the PC equivalent 
of the mainframe version (RAMMET). STAR is the recommended preprocessor 
for use in applications employing joint frequency distributions (wind 
direction and wind speed by stability class) based on NWS data. PCSTAR 
is the PC equivalent of the mainframe version (STAR). MPRM is the 
recommended preprocessor for use in applications employing on-site 
meteorological data. The latest version (MPRM 1.3) has been configured 
to implement the SRDT method for estimating P-G stability categories. 
MPRM is a general purpose meteorological data preprocessor which 
supports regulatory models requiring RAMMET formatted data and STAR 
formatted data. In addition to on-site data, MPRM provides equivalent 
processing of NWS data. METPRO is the required meteorological data 
preprocessor for use with CTDMPLUS. All of the above mentioned data 
preprocessors are available for downloading from the SCRAM BBS. \19\

    Table 9-3--Averaging Times for Site-Specific Wind and Turbulence
                              Measurements
------------------------------------------------------------------------
                 Parameter                         Averaging  time
------------------------------------------------------------------------
Surface wind speed (for use in stability    1-hr.
 determinations).
Transport direction.......................  1-hr.
Dilution wind speed.......................  1-hr.
Turbulence measurements (E and     1-hr.\1\
 A) for use in stability
 determinations.
------------------------------------------------------------------------
\1\ To minimize meander effects in A when wind conditions are
  light and/or variable, determine the hourly average  value
  from four sequential 15-minute 's according to the following
  formula:

      
    [GRAPHIC] [TIFF OMITTED] TR12AU96.000
    
                        9.3.4 Treatment of Calms

                           9.3.4.1 Discussion

    a. Treatment of calm or light and variable wind poses a special 
problem in model applications since Gaussian models assume that 
concentration is inversely proportional to wind speed. Furthermore, 
concentrations become unrealistically large when wind speeds less than 1 
m/s are input to the model. A procedure has been developed for use with 
NWS data to prevent the occurrence of overly conservative concentration 
estimates during periods of calms. This procedure acknowledges that a 
Gaussian plume model does not apply during calm conditions and that our 
knowledge of plume behavior and wind patterns during these conditions 
does not, at present, permit the development of a better technique. 
Therefore, the procedure disregards hours which are identified as calm. 
The hour is treated as missing and a convention for handling missing 
hours is recommended.
    b. Preprocessed meteorological data input to most appendix A EPA 
models substitute a 1.00 m/s wind speed and the previous direction for 
the calm hour. The new treatment of calms in those models attempts to 
identify the original calm cases by checking for a 1.00 m/s wind speed 
coincident with a wind direction equal to the previous hour's wind 
direction. Such cases are then treated in a prescribed manner when 
estimating short term concentrations.

                         9.3.4.2 Recommendations

    a. Hourly concentrations calculated with Gaussian models using calms 
should not be considered valid; the wind and concentration estimates for 
these hours should be disregarded and considered to be missing. Critical 
concentrations for 3-, 8-, and 24-hour averages should be calculated by 
dividing the sum of the hourly concentration 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. A post-processor computer program, CALMPRO \73\ has been prepared 
following these instructions and has been coded in RAM and ISC.
    b. The recommendations in paragraph a of this section apply to the 
use of calms for short term averages and do not apply to the 
determination of long term averages using ``STAR'' data summaries. Calms 
should continue to be included in the preparation of ``STAR'' summaries. 
A treatment for calms

[[Page 419]]

and very light winds is built into the software that produces the 
``STAR'' summaries.
    c. Stagnant conditions, including extended periods of calms, often 
produce high concentrations over wide areas for relatively long 
averaging periods. The standard short term Gaussian 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 8.2.10).
    d. When used in Gaussian models, measured on-site 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. Observations below the response threshold of the instrument 
are also set to 1 m/s but the wind direction from the previous hour is 
used. If the wind speed or direction can not be determined, that hour 
should be treated as missing and short term averages should then be 
calculated as described in paragraph a of this section.

                 10.0 Accuracy and Uncertainty of Models

                             10.1 Discussion

    a. Increasing reliance has been placed on concentration estimates 
from models as the primary basis for regulatory decisions concerning 
source permits and emission control requirements. In many situations, 
such as review of a proposed source, no practical alternative exists. 
Therefore, there is an obvious need to know how accurate models really 
are and how any uncertainty in the estimates affects regulatory 
decisions. EPA recognizes the need for incorporating such information 
and has sponsored workshops 11 74 on model accuracy, the 
possible ways to quantify accuracy, and on considerations in the 
incorporation of model accuracy and uncertainty in the regulatory 
process. The Second (EPA) Conference on Air Quality Modeling, August 
1982,75 was devoted to that subject.

                  10.1.1 Overview of Model Uncertainty

    a. Dispersion models generally attempt to estimate concentrations at 
specific sites that really represent an ensemble average of numerous 
repetitions of the same event. The event is characterized by measured or 
``known'' conditions that are input to the models, e.g., wind speed, 
mixed layer height, surface heat flux, emission characteristics, etc. 
However, in addition to the known conditions, there are unmeasured or 
unknown variations in the conditions of this event, e.g., unresolved 
details of the atmospheric flow such as the turbulent velocity field. 
These unknown conditions may vary among repetitions of the event. As a 
result, deviations in observed concentrations from their ensemble 
average, and from the concentrations estimated by the model, are likely 
to occur even though the known conditions are fixed. Even with a perfect 
model that predicts the correct ensemble average, there are likely to be 
deviations from the observed concentrations in individual repetitions of 
the event, due to variations in the unknown conditions. The statistics 
of these concentration residuals are termed ``inherent'' uncertainty. 
Available evidence suggests that this source of uncertainty alone may be 
responsible for a typical range of variation in concentrations of as 
much as #50 percent. \76\
    b. Moreover, there is ``reducible'' uncertainty \77\ associated with 
the model and its input conditions; neither models nor data bases are 
perfect. Reducible uncertainties are caused by: (1) Uncertainties in the 
input values of the known conditions--emission characteristics and 
meteorological data; (2) errors in the measured concentrations which are 
used to compute the concentration residuals; and (3) inadequate model 
physics and formulation. The ``reducible'' uncertainties can be 
minimized through better (more accurate and more representative) 
measurements and better model physics.
    c. To use the terminology correctly, reference to model accuracy 
should be limited to that portion of reducible uncertainty which deals 
with the 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. \78\ The statement of accuracy is based on statistical 
tests or performance measures such as bias, noise, correlation, etc. 
\11\ However, information that allows a distinction between 
contributions of the various elements of inherent and reducible 
uncertainty is only now beginning to emerge. As a result most 
discussions of the accuracy of models make no quantitative distinction 
between (1) Limitations of the model versus (2) limitations of the data 
base and of knowledge concerning atmospheric variability. The reader 
should be aware that statements on model accuracy and uncertainty may 
imply the need for improvements in model performance that even the 
``perfect'' model could not satisfy.

                    10.1.2 Studies of Model Accuracy

    a. A number of studies 79 80 have been conducted to 
examine model accuracy, particularly with respect to the reliability of 
short-term concentrations required for ambient standard and increment 
evaluations. The results of these studies are not surprising. Basically, 
they confirm what leading atmospheric scientists have said for some 
time: (1) Models are more reliable for estimating longer time-averaged 
concentrations than for estimating short-term concentrations at specific 
locations; and (2) the models are reasonably reliable in estimating the 
magnitude

[[Page 420]]

of highest concentrations occurring sometime, somewhere within an area. 
For example, errors in highest estimated concentrations of #10 to 40 
percent are found to be typical, \81\ i.e., certainly well within the 
often quoted factor-of-two accuracy that has long been recognized for 
these models. However, estimates of concentrations that occur at a 
specific time and site, are poorly correlated with actually observed 
concentrations and are much less reliable.
    b. As noted in paragraph a of this section, poor correlations 
between paired concentrations at fixed stations may be due to 
``reducible'' uncertainties in knowledge of the precise plume location 
and to unquantified inherent uncertainties. For example, Pasquill \82\ 
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. Uncertainty of 
five to 10 degrees in the measured wind direction, which transports the 
plume, 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.

              10.1.3 Use of Uncertainty in Decision-Making

    a. The accuracy of model estimates varies with the model used, the 
type of application, and site-specific characteristics. Thus, it is 
desirable to quantify the accuracy or uncertainty associated with 
concentration estimates used in decision-making. Communications between 
modelers and decision-makers must be fostered and further developed. 
Communications concerning concentration estimates currently exist in 
most cases, but the communications dealing with the accuracy of models 
and its meaning to the decision-maker are limited by the lack of a 
technical basis for quantifying and directly including uncertainty in 
decisions. Procedures for quantifying and interpreting uncertainty in 
the practical application of such concepts are only beginning to evolve; 
much study is still required.74 75 77
    b. In all applications of models an effort is encouraged to identify 
the reliability of the model estimates for that particular area and to 
determine the magnitude and sources of error associated with the use of 
the model. The analyst is responsible for recognizing and quantifying 
limitations in the accuracy, precision and sensitivity of the procedure. 
Information that might be useful to the decision-maker in recognizing 
the seriousness of potential air quality violations includes such model 
accuracy estimates as accuracy of peak predictions, bias, noise, 
correlation, frequency distribution, spatial extent of high 
concentration, etc. Both space/time pairing of estimates and 
measurements and unpaired comparisons are recommended. Emphasis should 
be on the highest concentrations and the averaging times of the 
standards or increments of concern. Where possible, confidence intervals 
about the statistical values should be provided. However, while such 
information can be provided by the modeler to the decision-maker, it is 
unclear how this information should be used to make an air pollution 
control decision. Given a range of possible outcomes, it is easiest and 
tends to ensure consistency if the decision-maker confines his judgment 
to use of the ``best estimate'' provided by the modeler (i.e., the 
design concentration estimated by a model recommended in the Guideline 
or an alternate model of known accuracy). This is an indication of the 
practical limitations imposed by current abilities of the technical 
community.
    c. To improve the basis for decision-making, EPA has developed and 
is continuing to study procedures for determining the accuracy of 
models, quantifying the uncertainty, and expressing confidence levels in 
decisions that are made concerning emissions controls.83 84 
However, work in this area involves ``breaking new ground'' with slow 
and sporadic progress likely. As a result, it may be necessary to 
continue using the ``best estimate'' until sufficient technical progress 
has been made to meaningfully implement such concepts dealing with 
uncertainty.

                       10.1.4 Evaluation of Models

    a. A number of actions are being taken to ensure that the best model 
is used correctly for each regulatory application and that a model is 
not arbitrarily imposed. First, the Guideline clearly recommends the 
most appropriate model be used in each case. Preferred models, based on 
a number of factors, are identified for many uses. General guidance on 
using alternatives to the preferred models is also provided. Second, all 
the models in eight categories (i.e., rural, urban, industrial complex, 
reactive pollutants, mobile source, complex terrain, visibility and long 
range transport) that are candidates for inclusion in the Guideline are 
being subjected to a systematic performance evaluation and a peer 
scientific review. \85\ The same data bases are being used to evaluate 
all models within each of eight categories. 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 recommended by the AMS Woods Hole Workshop, \11\ are being followed. 
The results of the scientific review are being incorporated in the 
Guideline and will be the basis for future revision.12 13 
Third, more specific

[[Page 421]]

information has been provided for justifying the site specific use of 
alternative models in the documents ``Interim Procedures for Evaluating 
Air Quality Models'', \15\ and the ``Protocol for Determining the Best 
Performing Model''. \17\ Together these documents provide methods that 
allow a judgment to be made as to what models are most appropriate for a 
specific application. For the present, performance and the theoretical 
evaluation of models are being used as an indirect means to quantify one 
element of uncertainty in air pollution regulatory decisions.
    b. In addition to performance evaluation of models, sensitivity 
analyses are encouraged since they can provide additional information on 
the effect of inaccuracies in the data bases and on the uncertainty in 
model estimates. Sensitivity analyses can aid in determining the effect 
of inaccuracies of variations or uncertainties in the data bases on the 
range of likely concentrations. Such information may be used to 
determine source impact and to evaluate control strategies. Where 
possible, information from such sensitivity analyses should be made 
available to the decision-maker with an appropriate interpretation of 
the effect on the critical concentrations.

                          10.2 Recommendations

    a. No specific guidance on the consideration of model uncertainty in 
decision-making is being given at this time. There is incomplete 
technical information on measures of model uncertainty that are most 
relevant to the decision-maker. It is not clear how a decisionmaker 
could use such information, particularly given limitations of the Clean 
Air Act. As procedures for considering uncertainty develop and become 
implementable, this guidance will be changed and expanded. For the 
present, continued use of the ``best estimate'' is acceptable and is 
consistent with Clean Air Act requirements.

                  11.0 Regulatory Application of Models

                             11.1 Discussion

    a. Procedures with respect to the review and analysis of air quality 
modeling and data analyses in support of SIP revisions, PSD permitting 
or other regulatory requirements need a certain amount of 
standardization to ensure consistency in the depth and comprehensiveness 
of both the review and the analysis itself. This section recommends 
procedures that permit some degree of standardization while at the same 
time allowing the flexibility needed to assure the technically best 
analysis for each regulatory application.
    b. Dispersion model estimates, especially with the support of 
measured air quality data, are the preferred basis for air quality 
demonstrations. Nevertheless, there are instances where the performance 
of recommended dispersion modeling techniques, by comparison with 
observed air quality data, may be shown to be less than acceptable. 
Also, there may be no recommended modeling procedure suitable for the 
situation. In these instances, emission limitations may be established 
solely on the basis of observed air quality data as would be applied to 
a modeling analysis. The same care should be given to the analyses of 
the air quality data as would be applied to a modeling analysis.
    c. The current NAAQS for SO2 and CO are both stated in 
terms of a concentration not to be exceeded more than once a year. There 
is only an annual standard for NO2 and a quarterly standard 
for Pb. The PM-10 and ozone standards permit the exceedance of a 
concentration on an average of not more than once a year; the convention 
is to average over a 3-year period.5 86 103 This represents a 
change from a deterministic to a more statistical form of the standard 
and permits some consideration to be given to unusual circumstances. The 
NAAQS are subjected to extensive review and possible revision every 5 
years.
    d. This section discusses general requirements for concentration 
estimates and identifies the relationship to emission limits. The 
recommendations in section 11.2 apply to: (1) revisions of State 
Implementation Plans; (2) the review of new sources and the prevention 
of significant deterioration (PSD); and (3) analyses of the emissions 
trades (``bubbles'').

                          11.2 Recommendations

                      11.2.1 Analysis Requirements

    a. Every effort should be made by the Regional Office to meet with 
all parties involved in either a SIP 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. An example of requirements for such an effort is 
contained in the Air Quality Analysis Checklist included here as 
appendix C. This checklist suggests the level of detail required 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 this preapplication meeting. The protocol 
should be written and agreed upon by the parties concerned, although a 
formal legal document is not intended. Changes in such a protocol are 
often required as the data collection and analysis progresses. However, 
the protocol establishes a common understanding of the requirements.

[[Page 422]]

    b. An air quality analysis should begin with a screening model to 
determine the potential of the proposed source or control strategy to 
violate the PSD increment or NAAQS. It is recommended that the screening 
techniques found in ``Screening Procedures for Estimating the Air 
Quality Impact of Stationary Sources'' \18\ be used for point source 
analyses. Screening procedures for area source analysis are discussed in 
``Applying Atmospheric Simulation Models to Air Quality Maintenance 
Areas''. \87\ For mobile source impact assessments the ``Guideline for 
Modeling Carbon Monoxide from Roadway Intersections'' \34\ is available.
    c. If the concentration estimates from screening techniques indicate 
that the PSD increment or NAAQS may be approached or exceeded, then a 
more refined modeling analysis is appropriate and the model user should 
select a model according to recommendations in sections 4.0-8.0. In some 
instances, no refined technique may be specified in this guide for the 
situation. The model user is then encouraged to submit a model developed 
specifically for the case at hand. If that is not possible, a screening 
technique may supply the needed results.
    d. Regional Offices should require permit applicants to incorporate 
the pollutant contributions of all sources into their analysis. Where 
necessary this may include emissions associated with growth in the area 
of impact of the new or modified source's impact. PSD air quality 
assessments should consider the amount of the allowable air quality 
increment that has already been granted to any other sources. Therefore, 
the most recent source applicant should model the existing or permitted 
sources in addition to the one currently under consideration. This would 
permit the use of newly acquired data or improved modeling techniques if 
such have become available since the last source was permitted. When 
remodeling, the worst case used in the previous modeling analysis should 
be one set of conditions modeled in the new analysis. All sources should 
be modeled for each set of meteorological conditions selected and for 
all receptor sites used in the previous applications as well as new 
sites specific to the new source.

         11.2.2 Use of Measured Data in Lieu of Model Estimates

    a. Modeling is the preferred method for determining emission 
limitations for both new and existing sources. When a preferred model is 
available, model results alone (including background) are sufficient. 
Monitoring will normally not be accepted as the sole basis for emission 
limitation determination in flat terrain areas. In some instances when 
the modeling technique available is only a screening technique, the 
addition of air quality data to the analysis may lend credence to model 
results.
    b. There are circumstances where there is no applicable model, and 
measured data may need to be used. Examples of such situations are: (1) 
complex terrain locations; (2) land/water interface areas; and (3) urban 
locations with a large fraction of particulate emissions from 
nontraditional sources. However, only in the case of an existing source 
should monitoring data alone be a basis for emission limits. In 
addition, the following items should be considered prior to the 
acceptance of the measured data:
    i. Does a monitoring network exist for the pollutants and averaging 
times of concern?
    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 data set 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 models are not applicable?
    c. The number of monitors required is a function of the problem 
being considered. The source configuration, terrain configuration, and 
meteorological variations all have an impact on number and placement of 
monitors. Decisions can only be made on a case-by-case basis. The 
Interim Procedures for Evaluating Air Quality Models \15\ should be used 
in establishing criteria for demonstrating that a model is not 
applicable.
    d. Sources should obtain approval from the Regional Office or 
reviewing authority for the monitoring network prior to the start of 
monitoring. A monitoring protocol agreed to by all concerned parties is 
highly desirable. 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.

                         11.2.3 Emission Limits

                     11.2.3.1 Design Concentrations

    a. Emission limits should be based on concentration estimates for 
the averaging time that results in the most stringent control 
requirements. The concentration used in specifying emission limits is 
called the design value or design concentration and is a sum of the 
concentration contributed by the source and the background 
concentration.

[[Page 423]]

    b. To determine the averaging time for the design value, the most 
restrictive National Ambient Air Quality Standard (NAAQS) should be 
identified by calculating, for each averaging time, the ratio of the 
applicable NAAQS (S)- background (B) to the predicted concentration (P) 
(i.e., (S-B)/P). The averaging time with the lowest ratio identifies the 
most restrictive standard. If the annual average is the most 
restrictive, the highest estimated annual average concentration from one 
or a number of years of data is the design value. When short term 
standards are most restrictive, it may be necessary to consider a 
broader range of concentrations than the highest value. For example, for 
pollutants such as SO2, the highest, second-highest 
concentration is the design value. For pollutants with statistically 
based NAAQS, the design value is found by determining the more 
restrictive of: (1) the short-term concentration that is not expected to 
be exceeded more than once per year over the period specified in the 
standard, or (2) the long-term concentration that is not expected to 
exceed the long-term NAAQS. Determination of design values for PM-10 is 
presented in more detail in the ``PM-10 SIP Development Guideline''. 
\108\
    c. When the highest, second-highest concentration is used in 
assessing potential violations of a short term NAAQS, criteria that are 
identified in ``Guideline for Interpretation of Air Quality 
Standards''88 should be followed. This guidance specifies 
that a violation of a short term standard occurs at a site when the 
standard is exceeded a second time. Thus, emission limits that protect 
standards for averaging times of 24 hours or less are appropriately 
based on the highest, second-highest estimated concentration plus a 
background concentration which can reasonably be assumed to occur with 
the concentration.

           11.2.3.2 NAAQS Analyses for New or Modified Sources

    a. For new or modified sources predicted to have a significant 
ambient impact \63\ and to be located in areas designated attainment or 
unclassifiable for the SO2, Pb, NO2, or CO NAAQS, 
the demonstration as to whether the source will cause or contribute to 
an air quality violation should be based on: (1) the highest estimated 
annual average concentration determined from annual averages of 
individual years; or (2) the highest, second-highest estimated 
concentration for averaging times of 24-hours or less; and (3) the 
significance of the spatial and temporal contribution to any modeled 
violation. For Pb, the highest estimated concentration based on an 
individual calendar quarter averaging period should be used. Background 
concentrations should be added to the estimated impact of the source. 
The most restrictive standard should be used in all cases to assess the 
threat of an air quality violation. For new or modified sources 
predicted to have a significant ambient impact \63\ in areas designated 
attainment or unclassifiable for the PM-10 NAAQS, the demonstration of 
whether or not the source will cause or contribute to an air quality 
violation should be based on sufficient data to show whether: (1) the 
projected 24-hour average concentrations will exceed the 24-hour NAAQS 
more than once per year, on average; (2) the expected (i.e., average) 
annual mean concentration will exceed the annual NAAQS; and (3) the 
source contributes significantly, in a temporal and spatial sense, to 
any modeled violation.

             11.2.3.3 PSD Air Quality Increments and Impacts

    a. The allowable PSD increments for criteria pollutants are 
established by regulation and cited in Sec. 51.166. These maximum 
allowable increases in pollutant concentrations may be exceeded once per 
year at each site, except for the annual increment that may not be 
exceeded. The highest, second-highest increase in estimated 
concentrations for the short term averages as determined by a model 
should be less than or equal to the permitted increment. The modeled 
annual averages should not exceed the increment.
    b. Screening techniques defined in sections 4.0 and 5.0 can 
sometimes be used to estimate short term incremental concentrations for 
the first new source that triggers the baseline in a given area. 
However, when multiple increment-consuming sources are involved in the 
calculation, the use of a refined model with at least 1 year of on-site 
or 5 years of off-site NWS data is normally required. In such cases, 
sequential modeling must demonstrate that the allowable increments are 
not exceeded temporally and spatially, i.e., for all receptors for each 
time period throughout the year(s) (time period means the appropriate 
PSD averaging time, e.g., 3-hour, 24-hour, etc.).
    c. The PSD regulations require an estimation of the SO2, 
particulate matter, and NO2 impact on any Class I area. 
Normally, Gaussian models should not be applied at distances greater 
than can be accommodated by the steady state assumptions inherent in 
such models. The maximum distance for refined Gaussian model application 
for regulatory purposes is generally considered to be 50km. Beyond the 
50km range, screening techniques may be used to determine if more 
refined modeling is needed. If refined models are needed, long range 
transport models should be considered in accordance with section 7.2.6. 
As previously noted in sections 3.0 and 7.0, the need to involve the 
Federal Land Manager in decisions on potential air quality

[[Page 424]]

impacts, particularly in relation to PSD Class I areas, cannot be 
overemphasized.

               11.2.3.4 Emissions Trading Policy (Bubbles)

    a. EPA's final Emissions Trading Policy, commonly referred to as the 
``bubble policy,'' was published in the Federal Register in 
1986.89 Principles contained in the policy should be used to 
evaluate ambient impacts of emission trading activities.
    b. Emission increases and decreases within the bubble should result 
in ambient air quality equivalence. Two levels of analysis are defined 
for establishing this equivalence. In a Level I analysis the source 
configuration and setting must meet certain limitations (defined in the 
policy) that ensure ambient equivalence; no modeling is required. In a 
Level II analysis a modeling demonstration of ambient equivalence is 
required but only the sources involved in the emissions trade are 
modeled. The resulting ambient estimates of net increases/decreases are 
compared to a set of significance levels to determine if the bubble can 
be approved. A Level II analysis requires the use of a refined model and 
the most recent readily available full year of representative 
meteorological data. Sequential modeling must demonstrate that the 
significance levels are met temporally and spatially, i.e., for all 
receptors for each time period throughout the year (time period means 
the appropriate NAAQS averaging time, e.g., 3-hour, 24-hour, etc.).
    c. For those bubbles that cannot meet the Level I or Level II 
requirements, the Emissions Trading Policy allows for a Level III 
analysis. A Level III analysis, from a modeling standpoint, is generally 
equivalent to the requirements for a standard SIP revision where all 
sources (and background) are considered and the estimates are compared 
to the NAAQS as in section 11.2.3.2.
    d. The Emissions Trading Policy allows States to adopt generic 
regulations for processing bubbles. The modeling procedures recommended 
in the Guideline apply to such generic regulations. However, an added 
requirement is that the modeling procedures contained in any generic 
regulation must be replicable such that there is no doubt as to how each 
individual bubble will be modeled. In general this means that the 
models, the data bases and the procedures for applying the model must be 
defined in the regulation. The consequences of the replicability 
requirement are that bubbles for sources located in complex terrain and 
certain industrial sources where judgments must be made on source 
characterization cannot be handled generically.

                12.0 References g h
---------------------------------------------------------------------------

    \g\ Documents not available in the open literature or from the 
National Technical Information Service (NTIS) have been placed in Docket 
No. A-80-46 or A-88-04. Item Numbers for documents placed in the Docket 
are shown at the end of the reference.
    h Some EPA references, e.g., model user's guides, etc., 
are periodically revised. Users are referred to the SCRAM 
BBS19 to download updates or addenda; see section A.0 of this 
appendix.
---------------------------------------------------------------------------

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Applications. American Meteorological Society, Boston, MA; pp. 159-171. 
(Docket No. A-80-46, II-A-106)
    79. Bowne, N.E. and R.J. Londergan, 1983. Overview, Results, and 
Conclusions for the EPRI Plume Model Validation and Development Project: 
Plains Site. EPRI EA-3074. Electric Power Research Institute, Palo Alto, 
CA.
    80. Moore, G.E., T.E. Stoeckenius and D.A. Stewart, 1982. A Survey 
of Statistical Measures of Model Performance and Accuracy for Several 
Air Quality Models. EPA Publication No. EPA-450/4-83-001. U.S. 
Environmental Protection Agency, Research Triangle Park, NC. (NTIS No. 
PB 83-260810)
    81. Rhoads, R.G., 1981. Accuracy of Air Quality Models. Staff 
Report. U.S. Environmental Protection Agency, Research Triangle Park, 
NC. (Docket No. A-80-46, II-G-6)
    82. Pasquill, F., 1974. Atmospheric Diffusion, 2nd Edition. John 
Wiley and Sons, New York, NY; 479 pp.
    83. Austin, B.S., T.E. Stoeckenius, M.C. Dudik and T.S. Stocking, 
1988. User's Guide to the Expected Exceedances System. Systems 
Applications, Inc., San Rafael, CA. Prepared under Contract No. 68-02-
4352 Option I for the U.S. Environmental Protection Agency, Research 
Triangle Park, NC. (Docket No. A-88-04, II-I-3)
    84. Thrall, A.D., T.E. Stoeckenius and C.S. Burton, 1985. A Method 
for Calculating Dispersion Modeling Uncertainty Applied to the 
Regulation of an Emission Source. Systems Applications, Inc., San 
Rafael, CA. Prepared for the U.S. Environmental Protection Agency, 
Research Triangle Park, NC. (Docket No. A-80-46, IV-G-1)
    85. Environmental Protection Agency, 1981. Plan for Evaluating Model 
Performance. Staff Report. U.S. Environmental Protection Agency, 
Research Triangle Park, NC. (Docket No. A-80-46, II-G-6)
    86. Environmental Protection Agency, 1979. Guideline for the 
Interpretation of Ozone Air Quality Standards. EPA Publication No. EPA 
450/4-79-003. U.S. Environmental Protection Agency, Research Triangle 
Park, NC. (NTIS No. PB-292271)
    87. Environmental Protection Agency, 1974. Guidelines for Air 
Quality Maintenance Planning and Analysis, Volume 12: Applying 
Atmospheric Simulation Models to Air Quality Maintenance Areas. EPA 
Publication No. EPA-450/4-74-013. U.S. Environmental Protection Agency, 
Research Triangle Park, NC. (NTIS No. PB-237750)
    88. Environmental Protection Agency, 1977. Guidelines for 
Interpretation of Air Quality Standards (Revised). OAQPS No. 1.2-008. 
U.S. Environmental Protection Agency, Research Triangle Park, NC. (NTIS 
No. PB 81-196420)
    89. Environmental Protection Agency, 1986. Emissions Trading Policy 
Statement; General Principles for Creation, Banking, and Use of Emission 
Reduction Credits. Federal Register, 51: 43814-43860.
    90. Environmental Research and Technology, 1987. User's Guide to the 
Rough Terrain Diffusion Model (RTDM), Rev. 3.20. ERT Document No. P-
D535-585. Environmental Research and Technology, Inc., Concord, MA. 
(NTIS No. PB 88-171467)
    91. Burns, D.J., S.G. Perry and A.J. Cimorelli, 1991. An Advanced 
Screening Model for Complex Terrain Applications. Paper presented at the 
7th Joint Conference on Applications of Air Pollution Meteorology 
(cosponsored by the American Meteorological Society and the Air & Waste 
Management Association), January 13-18, 1991, New Orleans, LA.
    92. 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.
    93. Paumier, J.O., S.G. Perry and D.J. Burns, 1992. CTDMPLUS: A 
Dispersion Model for Sources near Complex Topography. Part II: 
Performance Characteristics. Journal of Applied Meteorology, 31(7): 646-
660.
    94. Environmental Protection Agency, 1986. Evaluation of Mobile 
Source Air Quality Simulation Models. EPA Publication No.

[[Page 429]]

EPA-450/4-86-002. U.S. Environmental Protection Agency, Research 
Triangle Park, NC. (NTIS No. PB 86-167293)
    95. Shannon, J.D., 1987. Mobile Source Modeling Review. A report 
prepared under a cooperative agreement with the Environmental Protection 
Agency. (Docket No. A-88-04, II-J-2)
    96. Environmental Protection Agency, 1991. Emission Inventory 
Requirements for Carbon Monoxide State Implementation Plans. EPA 
Publication No. EPA-450/4-91-011. U.S. Environmental Protection Agency, 
Research Triangle Park, NC. (NTIS No. PB 92-112150)
    97. Environmental Protection Agency, 1992. Guideline for Regulatory 
Application of the Urban Airshed Model for Areawide Carbon Monoxide. EPA 
Publication No. EPA-450/4-92-011a and b. U.S. Environmental Protection 
Agency, Research Triangle Park, NC. (NTIS Nos. PB 92-213222 and PB 92-
213230)
    98. Environmental Protection Agency, 1992. Technical Support 
Document to Aid States with the Development of Carbon Monoxide State 
Implementation Plans. EPA Publication No. EPA-452/R-92-003. U.S. 
Environmental Protection Agency, Research Triangle Park, NC. (NTIS No. 
PB 92-233055)
    99. Environmental Protection Agency, 1986. Evaluation of Short-Term 
Long-Range Transport Models, Volumes I and II. EPA Publication Nos. EPA-
450/4-86-016a and b. U.S. Environmental Protection Agency, Research 
Triangle Park, NC. (NTIS Nos. PB 87-142337 and PB 87-142345)
    100. McNider, R.T., 1987. Review of Short-Term Long-Range Models. A 
report prepared under a cooperative agreement with the Environmental 
Protection Agency. (Docket No. A-88-04, II-I-10)
    101. Lamb, R.G., 1983. A Regional Scale (1,000km) Model of 
Photochemical Air Pollution, Part I--Theoretical Formulation, Part II--
Input Processor Network Design, and Part III--Tests of Numerical 
Algorithms. EPA Publication Nos. EPA-600/3-83-035, EPA-600/3-84-085, and 
EPA-600/3-85-037. U.S. Environmental Protection Agency, Research 
Triangle Park, NC. (NTIS Nos. PB 83-207688, PB 84-232651, and PB 85-
203818, respectively)
    102. Young, J.O., M. Aissa, T.L. Boehm et al., 1989. Development of 
the Regional Oxidant Model, Version 2.1. EPA Publication No. EPA-600/3-
89-044. U.S. Environmental Protection Agency, Research Triangle Park, 
NC. (NTIS No. PB 89-194252)
    103. Environmental Protection Agency, 1991. The Regional Oxidant 
Model (ROM) User's Guide. Part 1: The ROM Preprocessors. EPA Publication 
No. EPA-600/8-90-083a (NTIS No. PB 91-171926); Part 2: The ROM Processor 
Network. EPA Publication No. EPA-600/8-90-083b (NTIS No. PB 91-171934); 
Part 3: The Core Model. EPA Publication No. EPA-600/8-90-083c (NTIS No. 
PB 91-171942). U.S. Environmental Protection Agency, Research Triangle 
Park, NC.
    104. Chang, J.S., R.A. Brost, I.S.A. Isaksen, S. Madronich, P. 
Middleton, W.R. Stockwell and C.J. Waleck, 1987. A Three-Dimensional 
Eulerian Acid Deposition Model: Physical Concepts and Formulation. 
Journal of Geophysical Research, 92(D12): 14681-14700.
    105. Environmental Protection Agency, 1987. Protocol for Applying 
and Validating the CMB. U.S. Environmental Protection Agency. EPA 
Publication No. EPA-450/4-87-010. U.S. Environmental Protection Agency, 
Research Triangle Park, NC. (NTIS No. PB 87-206496)
    106. Environmental Protection Agency, 1987. Protocol for Reconciling 
Differences Among Receptor and Dispersion Models. EPA Publication No. 
EPA-450/4-87-008. U.S. Environmental Protection Agency, Research 
Triangle Park, NC. (NTIS No. PB 87-206504)
    107. Environmental Protection Agency, 1988. Chemical Mass Balance 
Model Diagnostics. EPA Publication No. EPA-450/4-88-005. U.S. 
Environmental Protection Agency, Research Triangle Park, NC. (NTIS No. 
PB 88-208319)
    108. Environmental Protection Agency, 1987. PM-10 SIP Development 
Guideline. EPA Publication No. EPA-450/2-86-001. U.S. Environmental 
Protection Agency, Research Triangle Park, NC. (NTIS No. PB 87-206488)
    109. Environmental Protection Agency, 1987. Example Modeling to 
Illustrate SIP Development for The PM-10 NAAQS. EPA Publication No. EPA-
450/4-87-012. U.S. Environmental Protection Agency, Research Triangle 
Park, NC. (NTIS No. PB 87-205191)
    110. Sestak, M.L. and A.R. Riebau, 1988. SASEM Simple Approach Smoke 
Estimation Model. U.S. Bureau of Land Management, Technical Note 382. 
BLM/YA/PT-88/003 + 7000. Available from Printed Materials Distribution 
Section, BLM Service Center (SC-658B), Denver, CO 80225-0047. (NTIS No. 
PB 90-185653)
    111. Environmental Protection Agency, 1992. A Modeling Protocol for 
Applying Mesopuff II to Long Range Transport Problems. EPA Publication 
No. EPA-454/R-92-021. U.S. Environmental Protection Agency, Research 
Triangle Park, NC.
    112. DiCristofaro, D.C. and S.R. Hanna, 1989. The Offshore and 
Coastal Dispersion (OCD) Model, Volume I: User's Guide, Volume II: 
Appendices. Version 4 Prepared for Minerals Management Services by Sigma 
Research Corporation, Westford, MA. (Docket No. A-88-04, II-D-A-06)
    113. Federal Aviation Administration, 1988. A Microcomputer 
Pollution Model for Civilian Airports and Air Force Bases, Model 
Description, Model Application and Background, and EDMS User's Guide 
(June 1991). Federal Aviation Administration Publication Nos. FAA-EE-88-
4 and 5; FAA-EE-91-3, respectively. United States Air Force Publication 
Nos. ESL-TR-88-53 and 55; ESL-TR-

[[Page 430]]

91-31, respectively. Federal Aviation Administration, Office of 
Environment and Energy, Washington, D.C. (NTIS Nos. ADA 199003, ADA 
199794, and ADA 240528, respectively)
    114. Environmental Protection Agency, 1992. Workbook of Screening 
Techniques for Assessing Impacts of Toxic Air Pollutants (Revised). EPA 
Publication No. EPA-454/R-92-024. U.S. Environmental Protection Agency, 
Research Triangle Park, NC.
    115. Environmental Protection Agency, 1990. User's Guide to TSCREEN: 
A Model for Screening Toxic Air Pollutant Concentrations. EPA 
Publication No. EPA-450/4-90-013. U.S. Environmental Protection Agency, 
Research Triangle Park, NC. (NTIS No. PB 91-141820)
    116. Environmental Protection Agency, 1989. Hazardous Waste TSDF 
Fugitive Particulate Matter Air Emissions Guidance Document. EPA 
Publication No. EPA-450/3-89-019. U.S. Environmental Protection Agency, 
Research Triangle Park, NC. (NTIS No. PB 90-103250)
    117. Environmental Protection Agency, 1989. Procedures for 
Conducting Air Pathway Analyses for Superfund Applications, Volume I 
Applications of Air Pathway Analyses for Superfund Activities and Volume 
IV Procedures for Dispersion Modeling and Air Monitoring for Superfund 
Air Pathway Analysis, EPA-450/1-89-001 and 004. U.S. Environmental 
Protection Agency, Research Triangle Park, NC. (NTIS Nos. PB 89-113374 
and PB 89-113382)
    118. Environmental Protection Agency, 1988. Air Dispersion Modeling 
as Applied to Hazardous Waste Incinerator Evaluations, An Introduction 
For the Permit Writer. U.S. Environmental Protection Agency, Research 
Triangle Park, NC. (Docket No. A-88-04, II-J-10)
    119. Environmental Protection Agency, 1989. U.S. EPA Office of Toxic 
Substances Graphical Exposure Modeling System (GEMS) User's Guide and 
GAMS Version 3.0 User's Guide (DRAFT). Prepared under Contract No. 68-
02-0481 for the U.S. Environmental Protection Agency, Washington, D.C. 
(Docket No. A-88-04, II-J-5a and II-J-13)
    120. Federal Emergency Management Agency, 1989. Handbook of Chemical 
Hazard Analysis Procedures. Available on request by writing to: Federal 
Emergency Management Agency, Publications Office, 500 C Street, S.W., 
Washington, D.C. 20472.
    121. Environmental Protection Agency, 1987. Technical Guidance for 
Hazards Analysis: Emergency Planning for Extremely Hazardous Substances. 
Available on request by telephone: 1-800-535-0202.
    122. Environmental Protection Agency, 1988. Superfund Exposure 
Assessment Manual. EPA-540/1-88-001, OSWER Directive 9285.5-1. Office of 
Remedial Response, Washington, D.C. 20460. (NTIS No. PB 89-135859)
    123. Environmental Protection Agency, 1989. Incineration of Sewage 
Sludge; Technical Support Document. Office of Water Regulations and 
Standards, Washington, D.C. 20460. (NTIS No. PB 89-136592)
    124. Environmental Protection Agency, 1989. Sludge Incineration 
Modeling (SIM) System User's Guide (Draft). Office of Pesticides and 
Toxic Substances, Exposure Evaluation Division, Washington, D.C. 20460. 
(NTIS No. PB 89-138762)
    125. Environmental Protection Agency, 1989. Risk Assessment Guidance 
for Superfund. Volume I: Human Health Evaluation Manual Part A. (Interim 
Final). OSWER Directive 9285.7-01a. Office of Solid Waste and Emergency 
Response, Washington, D.C. 20460.
    126. Environmental Protection Agency, 1986. User's Manual for the 
Human Exposure Model (HEM). EPA Publication No. EPA-450/5-86-001. Office 
of Air Quality Planning and Standards, Research Triangle Park, NC. 
27711.
    127. Environmental Protection Agency, 1992. A Tiered Modeling 
Approach for Assessing the Risks Due to Sources of Hazardous Air 
Pollutants. EPA Publication No. EPA-450/4-92-001. Environmental 
Protection Agency, Research Triangle Park, NC. (NTIS No. PB 92-164748)
    128. Environmental Protection Agency, 1992. Toxic Modeling System 
Short-term (TOXST) User's Guide. EPA Publication No. EPA-450/4-92-002. 
Environmental Protection Agency, Research Triangle Park, NC.
    129. Environmental Protection Agency, 1992. Toxic Modeling System 
Long-term (TOXLT) User's Guide. EPA Publication No. EPA-450/4-92-003. 
Environmental Protection Agency, Research Triangle Park, NC.
    130. Environmental Protection Agency, 1989. User's Guide for the 
DEGADIS 2.1 Dense Gas Dispersion Model. EPA Publication No. EPA-450/4-
89-019. U.S. Environmental Protection Agency, Research Triangle Park, 
NC. (NTIS No. PB 90-213893)
    131. Environmental Protection Agency, 1993. Guidance on the 
Application of Refined Models for Air Toxics Releases. EPA Publication 
No. EPA-450/4-91-007. Environmental Protection Agency, Research Triangle 
Park, NC. (NTIS No. PB 91-190983)
    132. Perry, R.H. and Chilton, C.H., 1973. Chemical Engineers' 
Handbook, Fifth Edition, McGraw-Hill Book Company, New York, NY.
    133. Environmental Protection Agency, 1988. User's Guide to SDM--A 
Shoreline Dispersion Model. EPA Publication No. EPA-450/4-88-017. U.S. 
Environmental Protection Agency, Research Triangle Park, NC. (NTIS No. 
PB 89-164305)
    134. Environmental Protection Agency, 1987. Analysis and Evaluation 
of Statistical

[[Page 431]]

Coastal Fumigation Models. EPA Publication No. EPA-450/4-87-002. U.S. 
Environmental Protection Agency, Research Triangle Park, NC. (NTIS No. 
PB 87-175519)
    135. Environmental Protection Agency, 1996. Meteorological Processor 
for Regulatory Models (MPRM) User's Guide. EPA Publication No. EPA-454/
B-96-002. U.S. Environmental Protection Agency, Research Triangle Park, 
NC. (NTIS No. PB 96-180518)
    136. 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)
    137. Environmental Protection Agency, 1993. An Evaluation of a Solar 
Radiation/Delta-T (SRDT) Method for Estimating Pasquill-Gifford (P-G) 
Stability Categories. EPA Publication No. EPA-454/R-93-055. U.S. 
Environmental Protection Agency, Research Triangle Park, NC. (NTIS No. 
PB 94-113958)
    138. Environmental Protection Agency, 1993. PCRAMMET User's Guide. 
EPA Publication No. EPA-454/B-93-009. U.S. Environmental Protection 
Agency, Research Triangle Park, NC.
    139. American Society of Mechanical Engineers, 1979. Recommended 
Guide for the Prediction of Airborne Effluents, Third Edition. American 
Society of Mechanical Engineers, New York, NY.

                     13.0 Bibliography i
---------------------------------------------------------------------------

    \i\ The documents listed here are major sources of supplemental 
information on the theory and application of mathematical air quality 
models.
---------------------------------------------------------------------------

    American Meteorological Society, 1971-1985. Symposia on Turbulence, 
Diffusion, and Air Pollution (1st-7th), Boston, MA.
    American Meteorological Society, 1977-1984. Joint Conferences on 
Applications of Air Pollution Meteorology (1st-4th). Sponsored by the 
American Meteorological Society and the Air Pollution Control 
Association, Boston, MA.
    American Meteorological Society, 1978. Accuracy of Dispersion 
Models. Bulletin of the American Meteorological Society, 59(8): 1025-
1026.
    American Meteorological Society, 1981. Air Quality Modeling and the 
Clean Air Act: Recommendations to EPA on Dispersion Modeling for 
Regulatory Applications, Boston, MA.
    Briggs, G.A., 1969. Plume Rise. U.S. Atomic Energy Commission 
Critical Review Series, Oak Ridge National Laboratory, Oak Ridge, TN.
    Dickerson, W.H. and P.H. Gudiksen, 1980. ASCOT FY 79 Program Report. 
Report UCRL--52899, ASCOT 80-1. Lawrence Livermore National Laboratory, 
Livermore, CA.
    Drake, R.L. and S.M. Barrager, 1979. Mathematical Models for 
Atmospheric Pollutants. EPRI EA-1131. Electric Power Research Institute, 
Palo Alto, CA.
    Environmental Protection Agency, 1978. Workbook for Comparison of 
Air Quality Models. EPA Publication No. EPA-450/2-78-028a and b. U.S. 
Environmental Protection Agency, Research Triangle Park, NC.
    Fox, D.G., and J.E. Fairobent, 1981. NCAQ Panel Examines Uses and 
Limitations of Air Quality Models. Bulletin of the American 
Meteorological Society, 62(2): 218-221.
    Gifford, F.A., 1976. Turbulent Diffusion Typing Schemes: A Review. 
Nuclear Safety, 17(1): 68-86.
    Gudiksen, P.H., and M.H. Dickerson, Eds., Executive Summary: 
Atmospheric Studies in Complex Terrain Technical Progress Report FY-1979 
Through FY-1983. Lawrence Livermore National Laboratory, Livermore, CA. 
(Docket Reference No. II-I-103).
    Hales, J.M., 1976. Tall Stacks and the Atmospheric Environment. EPA 
Publication No. EPA-450/3-76-007. U.S. Environmental Protection Agency, 
Research Triangle Park, NC.
    Hanna, S.R., G.A. Briggs, J. Deardorff, B.A. Egan, G.A. Gifford and 
F. Pasquill, 1977. AMS Workshop on Stability Classification Schemes And 
Sigma Curves--Summary of Recommendations. Bulletin of the American 
Meteorological Society, 58(12): 1305-1309.
    Hanna, S.R., G.A. Briggs and R.P. Hosker, Jr., 1982. Handbook on 
Atmospheric Diffusion. Technical Information Center, U.S. Department of 
Energy, Washington, D.C.
    Haugen, D.A., Workshop Coordinator, 1975. Lectures on Air Pollution 
and Environmental Impact Analyses. Sponsored by the American 
Meteorological Society, Boston, MA.
    Hoffnagle, G.F., M.E. Smith, T.V. Crawford and T.J. Lockhart, 1981. 
On-site Meteorological Instrumentation Requirements to Characterize 
Diffusion from Point Sources--A Workshop, 15-17 January 1980, Raleigh, 
NC. Bulletin of the American Meteorological Society, 62(2): 255-261.
    McMahon, R.A. and P.J. Denison, 1979. Empirical Atmospheric 
Deposition Parameters--A Survey. Atmospheric Environment, 13: 571-585.
    McRae, G.J., J.A. Leone and J.H. Seinfeld, 1983. Evaluation of 
Chemical Reaction Mechanisms for Photochemical Smog. Part I: Mechanism 
Descriptions and Documentation. EPA Publication No. EPA-600/3/83-086. 
U.S. Environmental Protection Agency, Research Triangle Park, NC.
    Pasquill, F. and F.B. Smith, 1983. Atmospheric Diffusion, 3rd 
Edition. Ellis Horwood Limited, Chichester, West Sussex, England, 438 
pp.
    Randerson, D., Ed., 1984. Atmospheric Science and Power Production. 
DOE/TIC

[[Page 432]]

2760l. Office of Scientific and Technical Information, U.S. Department 
of Energy, Oak Ridge, TN.
    Roberts, J.J., Ed., 1977. Report to U.S. EPA of the Specialists' 
Conference on the EPA Modeling Guideline. U.S. Environmental Protection 
Agency, Research Triangle Park, NC.
    Smith, M.E., Ed., 1973. Recommended Guide for the Prediction of the 
Dispersion of Airborne Effluents. The American Society of Mechanical 
Engineers, New York, NY.
    Stern, A.C., Ed., 1976. Air Pollution, Third Edition, Volume I: Air 
Pollutants, Their Transformation and Transport. Academic Press, New 
York, NY.
    Turner, D.B., 1979. Atmospheric Dispersion Modeling: A Critical 
Review. Journal of the Air Pollution Control Association, 29(5): 502-
519.
    Whiteman, C.D. and K.J. Allwine, 1982. Green River Ambient Model 
Assessment Program FY-1982 Progress Report. PNL-4520. Pacific Northwest 
Laboratory, Richland, WA.

                         14.0 Glossary of Terms

    Air quality. Ambient pollutant concentrations and their temporal and 
spatial distribution.
    Algorithm. A specific mathematical calculation procedure. A model 
may contain several algorithms.
    Background. Ambient pollutant concentrations due to:
    (1) Natural sources;
    (2) Nearby sources other than the one(s) currently under 
consideration; and
    (3) Unidentified sources.
    Calibrate. An objective adjustment using measured air quality data 
(e.g., an adjustment based on least-squares linear regression).
    Calm. For purposes of air quality modeling, calm is used to define 
the situation when the wind is indeterminate with regard to speed or 
direction.
    Complex terrain. Terrain exceeding the height of the stack being 
modeled.
    Computer code. A set of statements that comprise a computer program.
    Evaluate. To appraise the performance and accuracy of a model based 
on a comparison of concentration estimates with observed air quality 
data.
    Fluid modeling. Modeling conducted in a wind tunnel or water channel 
to quantitatively evaluate the influence of buildings and/or terrain on 
pollutant concentrations.
    Fugitive dust. Dust discharged to the atmosphere in an unconfined 
flow stream such as that from unpaved roads, storage piles and heavy 
construction operations.
    Model. A quantitative or mathematical representation or simulation 
which attempts to describe the characteristics or relationships of 
physical events.
    Preferred model. A refined model that is recommended for a specific 
type of regulatory application.
    Receptor. A location at which ambient air quality is measured or 
estimated.
    Receptor models. Procedures that examine an ambient monitor sample 
of particulate matter and the conditions of its collection to infer the 
types or relative mix of sources impacting on it during collection.
    Refined model. An analytical technique that provides a detailed 
treatment of physical and chemical atmospheric processes and requires 
detailed and precise input data. Specialized estimates are calculated 
that are useful for evaluating source impact relative to air quality 
standards and allowable increments. The estimates are more accurate than 
those obtained from conservative screening techniques.
    Rollback. A simple model that assumes that if emissions from each 
source affecting a given receptor are decreased by the same percentage, 
ambient air quality concentrations decrease proportionately.
    Screening technique. A relatively simple analysis technique to 
determine if a given source is likely to pose a threat to air quality. 
Concentration estimates from screening techniques are conservative.
    Simple terrain. An area where terrain features are all lower in 
elevation than the top of the stack of the source.

Appendix A to Appendix W of Part 51--Summaries of Preferred Air Quality 
                                 Models

                            Table of Contents

A.0 Introduction and Availability
A.1 Buoyant Line and Point Source Dispersion Model (BLP)
A.2 Caline3
A.3 Climatological Dispersion Model (CDM 2.0)
A.4 Gaussian-Plume Multiple Source Air Quality Algorithm (RAM)
A.5 Industrial Source Complex Model (ISC3)
A.6 Urban Airshed Model (UAM)
A.7 Offshore and Coastal Dispersion Model (OCD)
A.8 Emissions and Dispersion Modeling System (EDMS)
A.9 Complex Terrain Dispersion Model Plus Algorithms For Unstable 
          Situations (CTDMPLUS)
A.REF References

                    A.0 Introduction and Availability

    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, regulatory 
use,

[[Page 433]]

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.
    Many of these models have been subjected to a performance evaluation 
using comparisons with observed air quality data. A summary of such 
comparisons for models contained in this appendix is included in Moore 
et al. (1982). 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.
    All models and user's documentation in this appendix are available 
from: Computer Products, National Technical Information Service (NTIS), 
U.S. Department of Commerce, Springfield, VA 22161, Phone: (703) 487-
4650. In addition, model codes and selected, abridged user's guides are 
available from the Support Center for Regulatory Air Models Bulletin 
Board System \19\ (SCRAM BBS), telephone (919) 541-5742. The SCRAM BBS 
is an electronic bulletin board system designed to be user friendly and 
accessible from anywhere in the country. Model users with personal 
computers are encouraged to use the SCRAM BBS to download current model 
codes and text files.

        A.1 Buoyant Line and Point Source Dispersion Model (BLP)

                                Reference

    Schulman, Lloyd 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 computer code is available on the Support Center for Regulatory 
Models Bulletin Board System and also on diskette (as PB 90-500281) from 
the National Technical Information Service (see section A.0).

                                Abstract

    BLP is a Gaussian plume dispersion model designed to handle unique 
modeling problems associated with aluminum reduction plants, and other 
industrial sources where plume rise and downwash effects from stationary 
line sources are important.

                  a. Recommendations for Regulatory Use

    The BLP model is appropriate for the following applications:
    Aluminum reduction plants which contain buoyant, elevated line 
sources;
    Rural areas;
    Transport distances less than 50 kilometers;
    Simple terrain; and
    One hour to one year averaging times.
    The following options should be selected for regulatory 
applications:
    Rural (IRU=1) mixing height option;
    Default (no selection) for plume rise wind shear (LSHEAR), 
transitional point source plume rise (LTRANS), vertical potential 
temperature gradient (DTHTA), vertical wind speed power law profile 
exponents (PEXP), maximum variation in number of stability classes per 
hour (IDELS), pollutant decay (DECFAC), the constant in Briggs' stable 
plume rise equation (CONST2), constant in Briggs' neutral plume rise 
equation (CONST3), convergence criterion for the line source 
calculations (CRIT), and maximum iterations allowed for line source 
calculations (MAXIT); and
    Terrain option (TERAN) set equal to 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
    For other applications, BLP can be used if it can be demonstrated to 
give the same estimates as a recommended model for the same application, 
and will subsequently be executed in that mode.
    BLP can be used on a case-by-case basis with specific options not 
available in a recommended model if it can be demonstrated, using the 
criteria in section 3.2, that the model is more appropriate for a 
specific application.

                          b. Input Requirements

    Source data: point sources require stack location, elevation of 
stack base, physical stack height, stack inside diameter, stack gas exit 
velocity, stack gas exit temperature, and pollutant emission rate. 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.
    Meteorological data: hourly surface weather data from punched cards 
or from the preprocessor program RAMMET which provides hourly stability 
class, wind direction, wind speed, temperature, and mixing height.
    Receptor data: locations and elevations of receptors, or location 
and size of receptor grid or request automatically generated receptor 
grid.

                                c. Output

    Printed output (from a separate post-processor program) includes:

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    Total concentration or, optionally, source contribution analysis; 
monthly and annual frequency distributions for 1-, 3-, and 24-hour 
average concentrations; tables of 1-, 3-, and 24-hour average 
concentrations at each receptor; table of the annual (or length of run) 
average concentrations at each receptor;
    Five highest 1-, 3-, and 24-hour average concentrations at each 
receptor; and
    Fifty highest 1-, 3-, and 24-hour concentrations over the receptor 
field.

                            d. Type of Model

    BLP is a gaussian plume model.

                           e. Pollutant Types

    BLP may be used to model primary pollutants. This model does not 
treat settling and deposition.

                     f. Source-Receptor Relationship

    BLP treats up to 50 point sources, 10 parallel line sources, and 100 
receptors arbitrarily located.
    User-input topographic elevation is applied for each stack and each 
receptor.

                            g. Plume Behavior

    BLP uses plume rise formulas of Schulman and Scire (1980).
    Vertical potential temperature gradients of 0.02 Kelvin per meter 
for E stability and 0.035 Kelvin per meter are used for stable plume 
rise calculations. An option for user input values is included.
    Transitional rise is used for line sources.
    Option to suppress the use of transitional plume rise for point 
sources is included.
    The building downwash algorithm of Schulman and Scire (1980) is 
used.

                           h. Horizontal Winds

    Constant, uniform (steady-state) wind is assumed for an hour.
    Straight line plume transport is assumed to all downwind distances.
    Wind speeds profile exponents of 0.10, 0.15, 0.20, 0.25, 0.30, and 
0.30 are used for stability classes A through F, respectively. An option 
for user-defined values and an option to suppress the use of the wind 
speed profile feature are included.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Rural dispersion coefficients are from Turner (1969), with no 
adjustment made for variations in surface roughness or averaging time.
    Six stability classes are used.

                         k. Vertical Dispersion

    Rural dispersion coefficients are from Turner (1969), with no 
adjustment made for variations in surface roughness.
    Six stability classes are used.
    Mixing height is accounted for with multiple reflections until the 
vertical plume standard deviation equals 1.6 times the mixing height; 
uniform mixing is assumed beyond that point.
    Perfect reflection at the ground is assumed.

                       l. Chemical Transformation

    Chemical transformations are treated using linear decay. Decay rate 
is input by the user.

                           m. Physical Removal

    Physical removal is not explicitly treated.

                          n. Evaluation Studies

    Schulman, L.L. and J.S. Scire, 1980. Buoyant Line and Point Source 
(BLP) Dispersion Model User's Guide, P-7304B. Environmental Research and 
Technology, Inc., Concord, MA.
    Scire, J.S. and L.L. Schulman, 1981. Evaluation of the BLP and ISC 
Models with SF6 Tracer Data and SO2 Measurements 
at Aluminum Reduction Plants. APCA Specialty Conference on Dispersion 
Modeling for Complex Sources, St. Louis, MO.

                               A.2 CALINE3

                                Reference

    Benson, Paul E., 1979. CALINE3--A Versatile Dispersion Model for 
Predicting Air Pollutant Levels Near Highways and Arterial Streets. 
Interim Report, Report Number FHWA/CA/TL-79/23. Federal Highway 
Administration, Washington, D.C. (NTIS No. PB 80-220841)

                              Availability

    The CALINE3 model is available on diskette (as PB 95-502712) from 
NTIS. The source code and user's guide are also available on the Support 
Center for Regulatory Models Bulletin Board System (see section A.0).

                                Abstract

    CALINE3 can be used to estimate the concentrations of nonreactive 
pollutants from highway traffic. This steady-state Gaussian model can be 
applied to determine air pollution concentrations at receptor locations 
downwind of ``at-grade,'' ``fill,'' ``bridge,'' and ``cut section'' 
highways located in relatively uncomplicated terrain. The model is 
applicable for any wind direction, highway orientation, and receptor 
location. The model has adjustments for averaging time and surface 
roughness, and can handle up to 20 links and 20 receptors. It also 
contains an

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algorithm for deposition and settling velocity so that particulate 
concentrations can be predicted.

                  a. Recommendations for Regulatory Use

    CALINE-3 is appropriate for the following applications:
    Highway (line) sources;
    Urban or rural areas;
    Simple terrain;
    Transport distances less than 50 kilometers; and
    One-hour to 24-hour averaging times.

                          b. Input Requirements

    Source data: up to 20 highway links classed as ``at-grade,'' 
``fill'' ``bridge,'' or ``depressed''; coordinates of link end points; 
traffic volume; emission factor; source height; and mixing zone width.
    Meteorological data: wind speed, wind angle (measured in degrees 
clockwise from the Y axis), stability class, mixing height, ambient 
(background to the highway) concentration of pollutant.
    Receptor data: coordinates and height above ground for each 
receptor. c.

                                c. Output

    Printed output includes concentration at each receptor for the 
specified meteorological condition.

                            d. Type of Model

    CALINE-3 is a Gaussian plume model.

                           e. Pollutant Types

    CALINE-3 may be used to model primary pollutants.

                     f. Source-Receptor Relationship

    Up to 20 highway links are treated.
    CALINE-3 applies user input location and emission rate for each 
link. User-input receptor locations are applied.

                            g. Plume Behavior

    Plume rise is not treated.

                           h. Horizontal Winds

    User-input hourly wind speed and direction are applied.
    Constant, uniform (steady-state) wind is assumed for an hour.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Six stability classes are used.
    Rural dispersion coefficients from Turner (1969) are used, with 
adjustment for roughness length and averaging time.
    Initial traffic-induced dispersion is handled implicitly by plume 
size parameters.

                         k. Vertical Dispersion

    Six stability classes are used.
    Empirical dispersion coefficients from Benson (1979) are used 
including an adjustment for roughness length.
    Initial traffic-induced dispersion is handled implicitly by plume 
size parameters.
    Adjustment for averaging time is included.

                       l. Chemical Transformation

    Not treated.

                           m. Physical Removal

    Optional deposition calculations are included.

                          n. Evaluation Studies

    Bemis, G.R. et al., 1977. Air Pollution and Roadway Location, 
Design, and Operation--Project Overview. FHWA-CA-TL-7080-77-25, Federal 
Highway Administration, Washington, D.C.
    Cadle, S.H. et al., 1976. Results of the General Motors Sulfate 
Dispersion Experiment, GMR-2107. General Motors Research Laboratories, 
Warren, MI.
    Dabberdt, W.F., 1975. Studies of Air Quality on and Near Highways, 
Project 2761. Stanford Research Institute, Menlo Park, CA.

              A.3 Climatological Dispersion Model (CDM 2.0)

                                Reference

    Irwin, J.S., T. Chico and J. Catalano, 1985. CDM 2.0--Climatological 
Dispersion Model--User's Guide. U.S. Environmental Protection Agency, 
Research Triangle Park, NC. (NTIS No. PB 86-136546)

                              Availability

    The source code and user's guide is available on the Support Center 
for Regulatory Models Bulletin Board System. The computer code is also 
available on diskette (as PB 90-500406) from the National Technical 
Information Service (see section A.0).

                                Abstract

    CDM is a climatological steady-state Gaussian plume model for 
determining long-term (seasonal or annual) arithmetic average pollutant 
concentrations at any ground-level receptor in an urban area.

                  a. Recommendations for Regulatory Use

    CDM is appropriate for the following applications:
    Point and area sources;
    Urban areas;
    Flat terrain;

[[Page 436]]

    Transport distances less than 50 kilometers;
    Long term averages over one month to one year or longer.
    The following option should be selected for regulatory applications:
    Set the regulatory ``default option'' (NDEF=1) which automatically 
selects stack tip downwash, final plume rise, buoyancy-induced 
dispersion (BID), and the appropriate wind profile exponents.
    Enter ``0'' for pollutant half-life for all pollutants except for 
SO2 in an urban setting. This entry results in no decay 
(infinite half-life) being calculated. For SO2 in an urban 
setting, the pollutant half-life (in hours) should be set to 4.0.

                          b. Input Requirements

    Source data: location, average emissions rates and heights of 
emissions for point and area sources. Point source data requirements 
also include stack gas temperature, stack gas exit velocity, and stack 
inside diameter for plume rise calculations for point sources.
    Meteorological data: stability wind rose (STAR deck day/night 
version), average mixing height and wind speed in each stability 
category, and average air temperature.
    Receptor data: cartesian coordinates of each receptor.

                                c. Output

    Printed output includes:
    Average concentrations for the period of the stability wind rose 
data (arithmetic mean only) at each receptor, and
    Optional point and area concentration rose for each receptor.

                            d. Type of Model

    CDM is a climatological Gaussian plume model.

                           e. Pollutant Types

    CDM may be used to model primary pollutants. Settling and deposition 
are not treated.

                     f. Source-Receptor Relationship

    CDM applies user-specified locations for all point sources and 
receptors.
    Area sources are input as multiples of a user-defined unit area 
source grid size.
    User specified release heights are applied for individual point 
sources and the area source grid.
    Actual separation between each source-receptor pair is used.
    The user may select a single height at or above ground level that 
applies to all receptors.
    No terrain differences between source and receptor are treated.

                            g. Plume Behavior

    CDM uses Briggs (1969, 1971, 1975) plume rise equations. Optionally 
a plume rise-wind speed product may be input for each point source.
    Stack tip downwash equation from Briggs (1974) is preferred for 
regulatory use. The Bjorklund and Bowers (1982) equation is also 
included.
    No plume rise is calculated for area sources.
    Does not treat fumigation or building downwash.

                           h. Horizontal Winds

    Wind data are input as a stability wind rose (joint frequency 
distribution of 16 wind directions, 6 wind classes, and 5 stability 
classes).
    Wind speed profile exponents for the urban case (Irwin, 1979; EPA, 
1980) are used, assuming the anemometer height is at 10.0 meters.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Pollutants are assumed evenly distributed across a 22.5 or 10.0 
degree sector.

                         k. Vertical Dispersion

    There are seven vertical dispersion parameter schemes, but the 
following is recommended for regulatory applications:
     Briggs-urban (Gifford, 1976).
    Mixing height has no effect until dispersion coefficient equals 0.8 
times the mixing height; uniform vertical mixing is assumed beyond that 
point.
    Buoyancy-induced dispersion (Pasquill, 1976) is included as an 
option. Perfect reflection is assumed at the ground.

                       l. Chemical Transformation

    Chemical transformations are treated using exponential decay. Half-
life is input by the user.

                           m. Physical Removal

    Physical removal is not explicitly treated.

                          n. Evaluation Studies

    Busse, A.D. and J.R. Zimmerman, 1973. User's Guide for the 
Climatological Dispersion Model--Appendix E. EPA Publication No. EPA/R4-
73-024. Office of Research and Development, Research Triangle Park, NC.
    Irwin, J.S. and T.M. Brown, 1985. A Sensitivity Analysis of the 
Treatment of Area Sources by the Climatological Dispersion Model. 
Journal of Air Pollution Control Association, 35: 359-364.

[[Page 437]]

    Londergan, R., D. Minott, D. Wachter and R. Fizz, 1983. Evaluation 
of Urban Air Quality Simulation Models, EPA Publication No. EPA-450/4-
83-020. U.S. Environmental Protection Agency, Research Triangle Park, 
NC.
    Zimmerman, J.R., 1971. Some Preliminary Results of Modeling from the 
Air Pollution Study of Ankara, Turkey, Proceedings of the Second Meeting 
of the Expert Panel on Air Pollution Modeling, NATO Committee on the 
Challenges of Modern Society, Paris, France.
    Zimmerman, J.R., 1972. The NATO/CCMS Air Pollution Study of St. 
Louis, Missouri. Presented at the Third Meeting of the Expert Panel on 
Air Pollution Modeling, NATO Committee on the Challenges of Modern 
Society, Paris, France.

     A.4 Gaussian-Plume Multiple Source Air Quality Algorithm (RAM)

                                Reference

    Turner, D.B. and J.H. Novak, 1978. User's Guide for RAM. Publication 
No. EPA-600/8-78-016, Vol. a and b. U.S. Environmental Protection 
Agency, Research Triangle Park, NC. (NTIS Nos. PB 294791 and PB 294792)
    Catalano, J.A., D.B. Turner and H. Novak, 1987. User's Guide for 
RAM--Second Edition. U.S. Environmental Protection Agency, Research 
Triangle Park, NC.

                              Availability

    The source code and user's guide is available on the Support Center 
for Regulatory Models Bulletin Board System. The computer code is also 
available on diskette (as PB 90-500315) from the National Technical 
Information Service (see section A.0).

                                Abstract

    RAM is a steady-state Gaussian plume model for estimating 
concentrations of relatively stable pollutants, for averaging times from 
an hour to a day, from point and area sources in a rural or urban 
setting. Level terrain is assumed. Calculations are performed for each 
hour.

                  a. Recommendations for Regulatory Use

    RAM is appropriate for the following applications:
    Point and area sources;
    Urban areas;
    Flat terrain;
    Transport distances less than 50 kilometers; and
    One hour to one year averaging times.
    The following options should be selected for regulatory 
applications:
    Set the regulatory ``default option'' to automatically select stack 
tip downwash, final plume rise, buoyancy-induced dispersion (BID), the 
new treatment for calms, the appropriate wind profile exponents, and the 
appropriate value for pollutant half-life.

                          b. Input Requirements

    Source data: point sources require location, emission rate, physical 
stack height, stack gas exit velocity, stack inside diameter and stack 
gas temperature. Area sources require location, size, emission rate, and 
height of emissions.
    Meteorological data: hourly surface weather data from the 
preprocessor program RAMMET which provides hourly stability class, wind 
direction, wind speed, temperature, and mixing height. Actual anemometer 
height (a single value) is also required.
    Receptor data: coordinates of each receptor. Options for automatic 
placement of receptors near expected concentration maxima, and a gridded 
receptor array are included.

                                c. Output

    Printed output optionally includes:
    One to 24-hour and annual average concentrations at each receptor,
    Limited individual source contribution list, and
    Highest through fifth highest concentrations at each receptor for 
period, with the highest and high, second-high values flagged.

                            d. Type of Model

    RAM is a Gaussian plume model.

                           e. Pollutant Types

    RAM may be used to model primary pollutants. Settling and deposition 
are not treated.

                     f. Source-Receptor Relationship

    RAM applies user-specified locations for all point sources and 
receptors. Area sources are input as multiples of a user-defined unit 
area source grid size.
    User specified stack heights are applied for individual point 
sources.
    Up to 3 effective release heights may be specified for the area 
sources. Area source release heights are assumed to be appropriate for a 
5 meter per second wind and to be inversely proportional to wind speed.
    Actual separation between each source-receptor pair is used.
    All receptors are assumed to be at the same height at or above 
ground level.
    No terrain differences between source and receptor are accounted 
for.

                            g. Plume Behavior

    RAM uses Briggs (1969, 1971, 1975) plume rise equations for final 
rise.
    Stack tip downwash equation from Briggs (1974) is used.
    A user supplied fraction of the area source height is treated as the 
physical height. The

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remainder is assumed to be plume rise for a 5 meter per second wind 
speed, and to be inversely proportional to wind speed.
    Fumigation and building downwash are not treated.

                           h. Horizontal Winds

    Constant, uniform (steady state) wind is assumed for an hour.
    Straight line plume transport is assumed to all downwind distances.
    Separate wind speed profile exponents (Irwin, 1979; EPA, 1980) for 
urban cases are used.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Urban dispersion coefficients from Briggs (Gifford, 1976) are used.
    Buoyancy-induced dispersion (Pasquill, 1976) is included.
    Six stability classes are used.

                         k. Vertical Dispersion

    Urban dispersion coefficients from Briggs (Gifford, 1976) are used.
    Buoyancy-induced dispersion (Pasquill, 1976) is included.
    Six stability classes are used.
    Mixing height is accounted for with multiple reflections until the 
vertical plume standard deviation equals 1.6 times the mixing height; 
uniform vertical mixing is assumed beyond that point.
    Perfect reflection is assumed at the ground.

                       l. Chemical Transformation

    Chemical transformations are treated using exponential decay. Half-
life is input by the user.

                           m. Physical Removal

    Physical removal is not explicitly treated.

                          n. Evaluation Studies

    Ellis, H., P. Lou, and G. Dalzell, 1980. Comparison Study of 
Measured and Predicted Concentrations with the RAM Model at Two Power 
Plants Along Lake Erie. Second Joint Conference on Applications of Air 
Pollution Meteorology, New Orleans, LA.
    Environmental Research and Technology, 1980. SO2 
Monitoring and RAM (Urban) Model Comparison Study in Summit County, 
Ohio. Document P-3618-152, Environmental Research & Technology, Inc., 
Concord, MA.
    Guldberg, P.H. and C.W. Kern, 1978. A Comparison Validation of the 
RAM and PTMTP Models for Short-Term Concentrations in Two Urban Areas. 
Journal of Air Pollution Control Association, 28: 907-910.
    Hodanbosi, R.R. and L.K. Peters, 1981. Evaluation of RAM Model for 
Cleveland, Ohio. Journal of Air Pollution Control Association, 31: 253-
255.
    Kennedy, K.H., R.D. Siegel and M.P. Steinberg, 1981. Case-Specific 
Evaluation of the RAM Atmospheric Dispersion Model in an Urban Area. 
74th Annual Meeting of the American Institute of Chemical Engineers, New 
Orleans, LA.
    Kummier, R.H., B. Cho, G. Roginski, R. Sinha and A. Greenburg, 1979. 
A Comparative Validation of the RAM and Modified SAI Models for Short 
Term SO2 Concentrations in Detroit. Journal of Air Pollution 
Control Association, 29: 720-723.
    Londergan, R.J., N.E. Bowne, D.R. Murray, H. Borenstein and J. 
Mangano, 1980. An Evaluation of Short-Term Air Quality Models Using 
Tracer Study Data. Report No. 4333, American Petroleum Institute, 
Washington, D.C.
    Londergan, R., D. Minott, D. Wackter and R. Fizz, 1983. Evaluation 
of Urban Air Quality Simulation Models. EPA Publication No. EPA-450/4-
83-020. U.S. Environmental Protection Agency, Research Triangle Park, 
NC.
    Morgenstern, P., M.J. Geraghty, and A. McKnight, 1979. A Comparative 
Study of the RAM (Urban) and RAMR (Rural) Models for Short-term 
SO2 Concentrations in Metropolitan Indianapolis. 72nd Annual 
Meeting of the Air Pollution Control Association, Cincinnati, OH.
    Ruff, R.E., 1980. Evaluation of the RAM Using the RAPS Data Base. 
Contract 68-02-2770, SRI International, Menlo Park, CA.

               A.5 Industrial Source Complex Model (ISC3)

                                Reference

    Environmental Protection Agency, 1995. User's Guide for the 
Industrial Source Complex (ISC3) Dispersion Models, Volumes 1 and 2. EPA 
Publication Nos. EPA-454/B-95-003a & b. Environmental Protection Agency, 
Research Triangle Park, NC. (NTIS Nos. PB 95-222741 and PB 95-222758, 
respectively)

                              Availability

    The model code is available on the Support Center for Regulatory Air 
Models Bulletin Board System. ISCST3 (as PB 96-502000) and ISCLT3 (PB 
96-502018) are also available on diskette from the National Technical 
Information Service (see section A.0).

                                Abstract

    The ISC3 model is a steady-state Gaussian plume model which can be 
used to assess pollutant concentrations from a wide variety of sources 
associated with an industrial source complex. This model can account for 
the following: settling and dry deposition of particles; downwash; area, 
line and volume

[[Page 439]]

sources; plume rise as a function of downwind distance; separation of 
point sources; and limited terrain adjustment. ISC3 operates in both 
long-term and short-term modes.

                  a. Recommendations for Regulatory Use

    ISC3 is appropriate for the following applications:
     Industrial source complexes;
     Rural or urban areas;
     Flat or rolling terrain;
     Transport distances less than 50 kilometers;
     1-hour to annual averaging times; and
     Continuous toxic air emissions.
    The following options should be selected for regulatory 
applications: For short term or long term modeling, set the regulatory 
``default option''; i.e., use the keyword DFAULT, which automatically 
selects stack tip downwash, final plume rise, buoyancy induced 
dispersion (BID), the vertical potential temperature gradient, a 
treatment for calms, the appropriate wind profile exponents, the 
appropriate value for pollutant half-life, and a revised building wake 
effects algorithm; set the ``rural option'' (use the keyword RURAL) or 
``urban option'' (use the keyword URBAN); and set the ``concentration 
option'' (use the keyword CONC).

                          b. Input Requirements

    Source data: location, emission rate, physical stack height, stack 
gas exit velocity, stack inside diameter, and stack gas temperature. 
Optional inputs include source elevation, building dimensions, particle 
size distribution with corresponding settling velocities, and surface 
reflection coefficients.
    Meteorological data: ISCST3 requires hourly surface weather data 
from the preprocessor program RAMMET, which provides hourly stability 
class, wind direction, wind speed, temperature, and mixing height. For 
ISCLT3, input includes stability wind rose (STAR deck), average 
afternoon mixing height, average morning mixing height, and average air 
temperature.
    Receptor data: coordinates and optional ground elevation for each 
receptor.

                                c. Output

    Printed output options include:
     Program control parameters, source data, and receptor data;
     Tables of hourly meteorological data for each specified 
day;
     ``N''-day average concentration or total deposition 
calculated at each receptor for any desired source combinations;
     Concentration or deposition values calculated for any 
desired source combinations at all receptors for any specified day or 
time period within the day;
     Tables of highest and second highest concentration or 
deposition values calculated at each receptor for each specified time 
period during a(n) ``N''-day period for any desired source combinations, 
and tables of the maximum 50 concentration or deposition values 
calculated for any desired source combinations for each specified time 
period.

                            d. Type of Model

    ISC3 is a Gaussian plume model. It has been revised to perform a 
double integration of the Gaussian plume kernel for area sources.

                           e. Pollutant Types

    ISC3 may be used to model primary pollutants and continuous releases 
of toxic and hazardous waste pollutants. Settling and deposition are 
treated.

                    f. Source-Receptor Relationships

    ISC3 applies user-specified locations for point, line, area and 
volume sources, and user-specified receptor locations or receptor rings.
    User input topographic evaluation for each receptor is used. 
Elevations above stack top are reduced to the stack top elevation, i.e., 
``terrain chopping''.
    User input height above ground level may be used when necessary to 
simulate impact at elevated or ``flag pole'' receptors, e.g., on 
buildings.
    Actual separation between each source-receptor pair is used.

                            g. Plume Behavior

    ISC3 uses Briggs (1969, 1971, 1975) plume rise equations for final 
rise.
    Stack tip downwash equation from Briggs (1974) is used.
    Revised building wake effects algorithm is used. For stacks higher 
than building height plus one-half the lesser of the building height or 
building width, the building wake algorithm of Huber and Snyder (1976) 
is used. For lower stacks, the building wake algorithm of Schulman and 
Scire (Schulman and Hanna, 1986) is used, but stack tip downwash and BID 
are not used.
    For rolling terrain (terrain not above stack height), plume 
centerline is horizontal at height of final rise above source.
    Fumigation is not treated.

                           h. Horizontal Winds

    Constant, uniform (steady-state) wind is assumed for each hour.
    Straight line plume transport is assumed to all downwind distances.
    Separate wind speed profile exponents (Irwin, 1979; EPA, 1980) for 
both rural and urban cases are used.
    An optional treatment for calm winds is included for short term 
modeling.

[[Page 440]]

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Rural dispersion coefficients from Turner (1969) are used, with no 
adjustments for surface roughness or averaging time.
    Urban dispersion coefficients from Briggs (Gifford, 1976) are used.
    Buoyancy induced dispersion (Pasquill, 1976) is included.
    Six stability classes are used.

                         k. Vertical Dispersion

    Rural dispersion coefficients from Turner (1969) are used, with no 
adjustments for surface roughness.
    Urban dispersion coefficients from Briggs (Gifford, 1976) are used.
    Buoyancy induced dispersion (Pasquill, 1976) is included.
    Six stability classes are used.
    Mixing height is accounted for with multiple reflections until the 
vertical plume standard deviation equals 1.6 times the mixing height; 
uniform vertical mixing is assumed beyond that point.
    Perfect reflection is assumed at the ground.

                       l. Chemical Transformation

    Chemical transformations are treated using exponential decay. Time 
constant is input by the user.

                           m. Physical Removal

    Dry deposition effects for particles are treated using a resistance 
formulation in which the deposition velocity is the sum of the 
resistances to pollutant transfer within the surface layer of the 
atmosphere, plus a gravitational settling term (EPA, 1994), based on the 
modified surface depletion scheme of Horst (1983).

                          n. Evaluation Studies

    Bowers, J.F. and A.J. Anderson, 1981. An Evaluation Study for the 
Industrial Source Complex (ISC) Dispersion Model, EPA Publication No. 
EPA-450/4-81-002. U.S. Environmental Protection Agency, Research 
Triangle Park, NC.
    Bowers, J.F., A.J. Anderson and W.R. Hargraves, 1982. Tests of the 
Industrial Source Complex (ISC) Dispersion Model at the Armco 
Middletown, Ohio Steel Mill. EPA Publication No. EPA-450/4-82-006. U.S. 
Environmental Protection Agency, Research Triangle Park, NC.
    Environmental Protection Agency, 1992. Comparison of a Revised Area 
Source Algorithm for the Industrial Source Complex Short Term Model and 
Wind Tunnel Data. EPA Publication No. EPA-454/R-92-014. U.S. 
Environmental Protection Agency, Research Triangle Park, NC. (NTIS No. 
PB 93-226751)
    Environmental Protection Agency, 1992. Sensitivity Analysis of a 
Revised Area Source Algorithm for the Industrial Source Complex Short 
Term Model. EPA Publication No. EPA-454/R-92-015. U.S. Environmental 
Protection Agency, Research Triangle Park, NC. (NTIS No. PB 93-226769)
    Environmental Protection Agency, 1992. Development and Evaluation of 
a Revised Area Source Algorithm for the Industrial source complex Long 
Term Model. EPA Publication No. EPA-454/R-92-016. U.S. Environmental 
Protection Agency, Research Triangle Park, NC. (NTIS No. PB 93-226777)
    Environmental Protection Agency, 1994. Development and Testing of a 
Dry Deposition Algorithm (Revised). EPA Publication No. EPA-454/R-94-
015. U.S. Environmental Protection Agency, Research Triangle Park, NC. 
(NTIS No. PB 94-183100)
    Scire, J.S. and L.L. Schulman, 1981. Evaluation of the BLP and ISC 
Models with SF6 Tracer Data and SO2 Measurements 
at Aluminum Reduction Plants. Air Pollution Control Association 
Specialty Conference on Dispersion Modeling for Complex Sources, St. 
Louis, MO.
    Schulman, L.L. and S.R. Hanna, 1986. Evaluation of Downwash 
Modification to the Industrial Source Complex Model. Journal of the Air 
Pollution Control Association, 36: 258-264.

                      A.6 Urban Airshed Model (UAM)

                                Reference

    Environmental Protection Agency, 1990. User's Guide for the Urban 
Airshed Model, Volume I-VIII. EPA Publication Nos. EPA-450/4-90-007a-c, 
d(R), e-g, and EPA-454/B-93-004, respectively. U.S. Environmental 
Protection Agency, Research Triangle Park, NC (NTIS Nos. PB 91-131227, 
PB 91-131235, PB 91-131243, PB 93-122380, PB 91-131268, PB 92-145382, 
and PB 92-224849, respectively, for Vols. I-VII).

                              Availability

    The model code is available on the Support Center for Regulatory Air 
Models Bulletin Board System (see section A.0).

                                Abstract

    UAM is an urban scale, three dimensional, grid type numerical 
simulation model. The model incorporates a condensed photochemical 
kinetics mechanism for urban atmospheres. The UAM is designed for 
computing ozone (O3) concentrations under short-term, 
episodic conditions lasting one or two days resulting from emissions of 
oxides of nitrogen (NOX), volatile organic compounds (VOC), 
and carbon monoxide (CO).

[[Page 441]]

The model treats urban VOC emissions as their carbon-bond surrogates.

                  a. Recommendations for Regulatory Use

    UAM is appropriate for the following applications: urban areas 
having significant ozone attainment problems and one hour averaging 
times.
    UAM has many options but no specific recommendations can be made at 
this time on all options. The reviewing agency should be consulted on 
selection of options to be used in regulatory applications.

                          b. Input Requirements

    Source data: gridded, hourly emissions of PAR, OLE, ETH, XYL, TOL, 
ALD2, FORM, ISOR, ETOTH, MEOH, CO, NO, and NO2 for low-level 
sources. For major elevated point sources, hourly emissions, stack 
height, stack diameter, exit velocity, and exit temperature.
    Meteorological data: hourly, gridded, divergence free, u and v wind 
components for each vertical level; hourly gridded mixing heights and 
surface temperatures; hourly exposure class; hourly vertical potential 
temperature gradient above and below the mixing height; hourly surface 
atmospheric pressure; hourly water mixing ratio; and gridded surface 
roughness lengths.
    Air quality data: concentration of all carbon bond 4 species at the 
beginning of the simulation for each grid cell; and hourly 
concentrations of each pollutant at each level along the inflow 
boundaries and top boundary of the modeling region.
    Other data requirements are: hourly mixed layer average, 
NO2 photolysis rates; and ozone surface uptake resistance 
along with associated gridded vegetation (scaling) factors.

                                c. Output

    Printed output includes:
     Gridded instantaneous concentration fields at user-
specified time intervals for user-specified pollutants and grid levels;
     Gridded time-average concentration fields for user-
specified time intervals, pollutants, and grid levels.

                            d. Type of Model

    UAM is a three dimensional, numerical, photochemical grid model.

                           e. Pollutant Types

    UAM may be used to model ozone (O3) formation from oxides 
of nitrogen (NOX) and volatile organic compound (VOC) 
emissions.

                     f. Source-Receptor Relationship

    Low-level area and point source emissions are specified within each 
surface grid cell. Emissions from major point sources are placed within 
cells aloft in accordance with calculated effective plume heights.
    Hourly average concentrations of each pollutant are calculated for 
all grid cells at each vertical level.

                            g. Plume Behavior

    Plume rise is calculated for major point sources using relationships 
recommended by Briggs (1971).

                           h. Horizontal Winds

    See Input Requirements.

                         i. Vertical Wind Speed

    Calculated at each vertical grid cell interface from the mass 
continuity relationship using the input gridded horizontal wind field.

                        j. Horizontal Dispersion

    Horizontal eddy diffusivity is set to a user specified constant 
value (nominally 50 m2/s).

                         k. Vertical Dispersion

    Vertical eddy diffusivities for unstable and neutral conditions 
calculated using relationships of Lamb et al. (1977); for stable 
conditions, the relationship of Businger and Arya (1974) is employed. 
Stability class, friction velocity, and Monin-Obukhov length determined 
using procedure of Liu et al. (1976).

                       l. Chemical Transformation

    UAM employs a simplified version of the Carbon-Bond IV Mechanism 
(CBM-IV) developed by Gery et al. (1988) employing various steady state 
approximations. The CBM-IV mechanism incorporated in UAM utilizes an 
updated simulation of PAN chemistry that includes a peroxy-peroxy 
radical termination reaction, significant when the atmosphere is 
NOX-limited (Gery et al., 1989). The current CBM-IV mechanism 
accommodates 34 species and 82 reactions.

                           m. Physical Removal

    Dry deposition of ozone and other pollutant species are calculated. 
Vegetation (scaling) factors are applied to the reference surface uptake 
resistance of each species depending on land use type.

                          n. Evaluation Studies

    Builtjes, P.J.H., K.D. van der Hurt and S.D. Reynolds, 1982. 
Evaluation of the Performance of a Photochemical Dispersion Model in 
Practical Applications. 13th International Technical Meeting on Air 
Pollution Modeling and Its Application, Ile des Embiez, France.
    Cole, H.S., D.E. Layland, G.K. Moss and C.F. Newberry, 1983. The St. 
Louis Ozone Modeling Project. EPA Publication No. EPA-450/4-83-019. U.S. 
Environmental Protection Agency, Research Triangle Park, NC.

[[Page 442]]

    Dennis, R.L., M.W. Downton and R.S. Keil, 1983. Evaluation of 
Performance Measures for an Urban Photochemical Model. EPA Publication 
No. EPA-450/4-83-021. U.S. Environmental Protection Agency, Research 
Triangle Park, NC.
    Haney, J.L. and T.N. Braverman, 1985. Evaluation and Application of 
the Urban Airshed Model in the Philadelphia Air Quality Control Region. 
EPA Publication No. EPA-450/4-85-003. U.S. Environmental Protection 
Agency, Research Triangle Park, NC.
    Layland, D.E. and H.S. Cole, 1983. A Review of Recent Applications 
of the SAI Urban Airshed Model. EPA Publication No. EPA-450/4-84-004. 
U.S. Environmental Protection Agency, Research Triangle Park, NC.
    Layland, D.E., S.D. Reynolds, H. Hogo and W.R. Oliver, 1983. 
Demonstration of Photochemical Grid Model Usage for Ozone Control 
Assessment. 76th Annual Meeting of the Air Pollution Control 
Association, Atlanta, GA.
    Morris, R.E. et al., 1990. Urban Airshed Model Study of Five Cities. 
EPA Publication No. EPA-450/4-90-006a-g. U.S. Environmental Protection 
Agency, Research Triangle Park, NC.
    Reynolds, S.D., H. Hogo, W.R. Oliver and L.E. Reid, 1982. 
Application of the SAI Airshed Model to the Tulsa Metropolitan Area, SAI 
No. 82004. Systems Applications, Inc., San Rafael, CA.
    Schere, K.L. and J.H. Shreffler, 1982. Final Evaluation of Urban-
Scale Photochemical Air Quality Simulation Models. EPA Publication No. 
EPA-600/3-82-094. U.S. Environmental Protection Agency, Research 
Triangle Park, NC.
    Seigneur C., T.W. Tesche, C.E. Reid, P.M. Roth, W.R. Oliver and J.C. 
Cassmassi, 1981. The Sensitivity of Complex Photochemical Model 
Estimates to Detail In Input Information, Appendix A--A Compilation of 
Simulation Results. EPA Publication No. EPA-450/4-81-031b. U.S. 
Environmental Protection Agency, Research Triangle Park, NC.
    South Coast Air Quality Management District, 1989. Air Quality 
Management Plan--Appendix V-R (Urban Airshed Model Performance 
Evaluation). El Monte, CA.
    Stern, R. and B. Scherer, 1982. Simulation of a Photochemical Smog 
Episode in the Rhine-Ruhr Area with a Three Dimensional Grid Model. 13th 
International Technical Meeting on Air Pollution Modeling and Its 
Application, Ile des Embiez, France.
    Tesche, T.W., C. Seigneur, L.E. Reid, P.M. Roth, W.R. Oliver and 
J.C. Cassmassi, 1981. The Sensitivity of Complex Photochemical Model 
Estimates to Detail in Input Information. EPA Publication No. EPA-450/4-
81-031a. U.S. Environmental Protection Agency, Research Triangle Park, 
NC.
    Tesche, T.W., W.R. Oliver, H. Hogo, P. Saxeena and J.L. Haney, 1983. 
Volume IV--Assessment of NOX Emission Control Requirements in 
the South Coast Air Basin--Appendix A. Performance Evaluation of the 
Systems Applications Airshed Model for the 26-27 June 1974 O3 
Episode in the South Coast Air Basin, SYSAPP 83/037. Systems 
Applications, Inc., San Rafael, CA.
    Tesche, T.W., W.R. Oliver, H. Hogo, P. Saxeena and J.L. Haney, 1983. 
Volume IV--Assessment of NOX Emission Control Requirements in 
the South Coast Air Basin--Appendix B. Performance Evaluation of the 
Systems Applications Airshed Model for the 7-8 November 1978 
NO2 Episode in the South Coast Air Basin, SYSAPP 83/038. 
Systems Applications, Inc., San Rafael, CA.
    Tesche, T.W., 1988. Accuracy of Ozone Air Quality Models. Journal of 
Environmental Engineering, 114(4): 739-752.

             A.7 Offshore and Coastal Dispersion Model (OCD)

                                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

    This model code is available on the Support Center for Regulatory 
Air Models Bulletin Board System and also on diskette (as PB 91-505230) 
from the National Technical Information Service (see section A.0).

                            Technical Contact

    Minerals Management Service, Attn: Mr. Dirk Herkhof, Parkway Atrium 
Building, 381 Elden Street, Herndon, VA 22070-4817, Phone: (703) 787-
1735.

                                Abstract

    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.
    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. Recommendations for Regulatory Use

    OCD has been recommended for use by the Minerals Management Service 
for emissions

[[Page 443]]

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 EPA Regional Office.

                          b. Input Requirements

    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.
    Meteorological data (over water): wind direction, wind speed, mixing 
height, relative humidity, air temperature, water surface temperature, 
vertical wind direction shear (optional), vertical temperature gradient 
(optional), turbulence intensities (optional).
    Meteorological data (over land): wind direction, wind speed, 
temperature, stability class, mixing height.
    Receptor data: location, height above local ground-level, ground-
level elevation above the water surface.

                                c. Output

    All input options, specification of sources, receptors and land/
Water map including locations of sources and receptors.
    Summary tables of five highest concentrations at each receptor for 
each averaging period, and average concentration for entire run period 
at each receptor.
    Optional case study printout with hourly plume and receptor 
characteristics. Optional table of annual impact assessment from non-
permanent activities.
    Concentration files written to disk or tape 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

    Up to 250 point sources, 5 area sources, or 1 line source and 180 
receptors may be used.
    Receptors and sources are allowed at any location.
    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

    As in MPTER, the basic plume rise algorithms are based on Briggs' 
recommendations.
    Momentum rise includes consideration of the stack angle from the 
vertical.
    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.
    Partial plume penetration of elevated inversions is included using 
the suggestions of Briggs (1975) and Weil and Brower (1984).
    Continuous shoreline fumigation is parametrized 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

    Constant, uniform wind is assumed for each hour.
    Overwater wind speed can be estimated from overland wind speed using 
relationship of Hsu (1981).
    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

    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.
    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.
    Formulas recommended by Pasquill (1976) are used to calculate 
buoyant plume enhancement and wind direction shear enhancement.
    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.

[[Page 444]]

                         k. Vertical Dispersion

    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.
    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.
    Formulas recommended by Pasquill (1976) are used to calculate 
buoyant plume enhancement.
    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, D.C.

           A.8 Emissions and Dispersion Modeling System (EDMS)

                                Reference

    Segal, H.M., 1991. ``EDMS--Microcomputer Pollution Model for 
Civilian Airports and Air Force Bases: User's Guide.'' FAA Report No. 
FAA-EE-91-3; USAF Report No. ESL-TR-91-31, Federal Aviation 
Administration, 800 Independence Avenue, S.W., Washington, D.C. 20591. 
(NTIS No. ADA 240528)
    Segal, H.M. and Hamilton, P.L., 1988. ``A Microcomputer Pollution 
Model for Civilian Airports and Air Force Bases--Model Description.'' 
FAA Report No. FAA-EE-88-4; USAF Report No. ESL-TR-88-53, Federal 
Aviation Administration, 800 Independence Avenue, S.W., Washington, D.C. 
20591. (NTIS No. ADA 199003)
    Segal, H.M., 1988. ``A Microcomputer Pollution Model for Civilian 
Airports and Air Force Bases--Model Application and Background.'' FAA 
Report No. FAA-EE-88-5; USAF Report No. ESL-TR-88-55, Federal Aviation 
Administration, 800 Independence Avenue, S.W., Washington, D.C. 20591. 
(NTIS No. ADA 199794)

                              Availability

    EDMS is available for $40 from: Federal Aviation Administration, 
Attn: Ms. Diana Liang, AEE-120, 800 Independence Avenue, S.W., 
Washington, D.C. 20591, Phone: (202) 267-3494.

                                Abstract

    EDMS is a combined emissions/dispersion model for assessing 
pollution at civilian airports and military air bases. This model, which 
was jointly developed by the Federal Aviation Administration (FAA) and 
the United States Air Force (USAF), produces an emission inventory of 
all airport sources and calculates concentrations produced by these 
sources at specified receptors. The system stores emission factors for 
fixed sources such as fuel storage tanks and incinerators and also for 
mobile sources such as automobiles or aircraft. EDMS incorporates an 
emissions model to calculate an emission inventory for each airport 
source and a dispersion model, the Graphical Input Microcomputer Model 
(GIMM) (Segal, 1983) to calculate pollutant concentrations produced by 
these sources at specified receptors. The GIMM, which processes point, 
area, and line sources, also incorporates a special meteorological 
preprocessor for processing up to one year of National Climatic Data 
Center (NCDC) hourly data. The model operates in both a screening and 
refined mode, accepting up to 170 sources and 10 receptors.

                  a. Recommendations for Regulatory Use

    EDMS is appropriate for the following applications:
     Cumulative effect of changes in aircraft operations, point 
source and mobile source emissions at airports or air bases;
     Simple terrain;
     Transport distances less than 50 kilometers; and
     1-hour to annual averaging times.

                          b. Input Requirements

    All data are entered through a ``runtime'' version of the Condor 
data base which is an

[[Page 445]]

integral part of EDMS. Typical entry items are source and receptor 
coordinates, percent cold starts, vehicles per hour, etc. Some point 
sources, such as heating plants, require stack height, stack diameter, 
and effluent temperature inputs.
    Wind speed, wind direction, hourly temperature, and Pasquill-Gifford 
stability category (P-G) are the meteorological inputs. They can be 
entered manually through the EDMS data entry screens or automatically 
through the processing of previously loaded NCDC hourly data.

                                c. Output

    Printed outputs consist of:
     A monthly and yearly emission inventory report for each 
source entered; and
     A concentration summing report for up to 8760 hours (one 
year) of data.

                            d. Type of Model

    For its emissions inventory calculations, EDMS uses algorithms 
consistent with the EPA Compilation of Air Pollutant Emission Factors, 
AP-42. For its dispersion calculations, EDMS uses the GIMM model which 
is described in reports FAA-EE-88-4 and FAA-EE-88-5, referenced above. 
GIMM uses a Gaussian plume algorithm.

                           e. Pollutant Types

    EDMS inventories and calculates the dispersion of carbon monoxide, 
nitrogen oxides, sulphur oxides, hydrocarbons, and suspended particles.

                     f. Source-Receptor Relationship

    Up to 170 sources and 10 receptors can be treated simultaneously. 
Area sources are treated as a series of lines that are positioned 
perpendicular to the wind.
    Line sources (roadways, runways) are modeled as a series of points. 
Terrain elevation differences between sources and receptors are 
neglected.
    Receptors are assumed to be at ground level.

                            g. Plume Behavior

    Plume rise is calculated for all point sources (heating plants, 
incinerators, etc.) using Briggs plume rise equations (Catalano, 1986; 
Briggs, 1969; Briggs, 1971; Briggs, 1972).
    Building and stack tip downwash effects are not treated.
    Roadway dispersion employs a modification to the Gaussian plume 
algorithms as suggested by Rao and Keenan (1980) to account for close-in 
vehicle-induced turbulence.

                           h. Horizontal Winds

    Steady state winds are assumed for each hour. Winds are assumed to 
be constant with altitude.
    Winds are entered manually by the user or automatically by reading 
previously loaded NCC annual data files.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed to be zero.

                        j. Horizontal Dispersion

    Four stability classes are used (P-G classes B through E).
    Horizontal dispersion coefficients are computed using a table look-
up and linear interpolation scheme. Coefficients are based on Pasquill 
(1976) as adapted by Petersen (1980).
    A modified coefficient table is used to account for traffic-enhanced 
turbulence near roadways. Coefficients are based upon data included in 
Rao and Keenan (1980).

                         k. Vertical Dispersion

    Four stability classes are used (P-G classes B through E).
    Vertical dispersion coefficients are computed using a table look-up 
and linear interpolation scheme. Coefficients are based on Pasquill 
(1976) as adapted by Petersen (1980).
    A modified coefficient table is used to account for traffic-enhanced 
turbulence near roadways. Coefficients are based upon data from Roa and 
Keenan (1980).

                       l. Chemical Transformation

    Chemical transformations are not accounted for.

                           m. Physical Removal

    Deposition is not treated.

                          n. Evaluation Studies

    Segal, H.M. and P.L. Hamilton, 1988. A Microcomputer Pollution Model 
for Civilian Airports and Air Force Bases--Model Description. FAA Report 
No. FAA-EE-88-4; USAF Report No. ESL-TR-88-53, Federal Aviation 
Administration, 800 Independence Avenue, S.W., Washington, D.C. 20591.
    Segal, H.M., 1988. A Microcomputer Pollution Model for Civilian 
Airports and Air Force Bases--Model Application and Background. FAA 
Report No. FAA-EE-88-5; USAF Report No. ESL-TR-88-55, Federal Aviation 
Administration, 800 Independence Avenue, S.W., Washington, D.C. 20591.

   A.9 Complex Terrain Dispersion Model Plus Algorithms for Unstable 
                          Situations (CTDMPLUS)

                                Reference

    Perry, S.G., D.J. Burns, L.H. Adams, R.J. Paine, M.G. Dennis, M.T. 
Mills, D.G.

[[Page 446]]

Strimaitis, R.J. Yamartino and E.M. Insley, 1989. User's Guide to the 
Complex Terrain Dispersion Model Plus Algorithms for Unstable Situations 
(CTDMPLUS). Volume 1: Model Descriptions and User Instructions. EPA 
Publication No. EPA-600/8-89-041. Environmental Protection Agency, 
Research Triangle Park, NC. (NTIS No. PB 89-181-424)
    Paine, R.J., D.G. Strimaitis, M.G. Dennis, R.J. Yamartino, M.T. 
Mills and E.M. Insley, 1987. User's Guide to the Complex Terrain 
Dispersion Model, Volume 1. EPA Publication No. EPA-600/8-87-058a. U.S. 
Environmental Protection Agency, Research Triangle Park, NC. (NTIS No. 
PB 88-162169)

                              Availability

    This model code is available on the Support Center for Regulatory 
Air Models Bulletin Board System and also on diskette (as PB 90-504119) 
from the National Technical Information Service (see section A.0).

                                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. Recommendation for 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
     One hour to annual averaging times when used with a post-
processor program such as CHAVG.

                          b. Input Requirements

    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.
    Meteorological data: the user must supply hourly averaged values of 
wind, temperature and turbulence data for creation of the basic 
meteorological data file (``PROFILE''). 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).
    Receptor data: receptor names (up to 400) and coordinates, and hill 
number (each receptor must have a hill number assigned).
    Terrain data: user inputs digitized contour information to the 
terrain preprocessor which creates the TERRAIN data file (for up to 25 
hills).

                                c. Output

    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
     Source-receptor location (line printer map).
    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
     Plume characteristics at each receptor, i.e.,
    -> distance in along-flow and cross flow direction
    -> effective plume-receptor height difference
    -> effective y & z values, 
both flat terrain and hill induced (the difference shows the effect of 
the hill)
    -> concentration components due to WRAP, LIFT and FLAT.
    If the user selects the TOPN option, a summary table of the top 4 
concentrations at each receptor is given. If the ISOR option is 
selected, a source contribution table for every hour will be printed.
    A separate disk file of predicted (1-hour only) concentrations 
(``CONC'') is written if the user chooses this option. Three forms of 
output are possible:
    (1) A binary file of concentrations, one value for each receptor in 
the hourly sequence as run;
    (2) A text file of concentrations, one value for each receptor in 
the hourly sequence as run; or
    (3) A text file as described above, but with a listing of receptor 
information (names, positions, hill number) at the beginning of the 
file.

[[Page 447]]

    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

    As in CTDM, the basic plume rise algorithms are based on Briggs' 
(1975) recommendations.
    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.
    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, 
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., 
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. 
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. 
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 II: 
Performance Characteristics. Journal of Applied Meteorology, 31(7): 646-
660.

                            A. REF References

    Benson, P.E., 1979. CALINE3--A Versatile Dispersion Model for 
Predicting Air Pollution Levels Near Highways and Arterial Streets. 
Interim Report, Report Number FHWA/CA/TL-79/23. Federal Highway 
Administration, Washington, D.C.
    Briggs, G.A., 1969. Plume Rise. U.S. Atomic Energy Commission 
Critical Review Series,

[[Page 448]]

Oak Ridge National Laboratory, Oak Ridge, TN. (NTIS No. TID-25075)
    Briggs, G.A., 1971. Some Recent Analyses of Plume Rise Observations. 
Proceedings of the Second International Clean Air Congress, edited by 
H.M. Englund and W.T. Berry. Academic Press, New York, NY.
    Briggs, G.A., 1974. Diffusion Estimation for Small Emissions. USAEC 
Report ATDL-106. U.S. Atomic Energy Commission, Oak Ridge, TN.
    Briggs, G.A., 1975. Plume Rise Predictions. Lectures on Air 
Pollution and Environmental Impact Analyses. American Meteorological 
Society, Boston, MA, pp. 59-111.
    Bjorklund, J.R. and J.F. Bowers, 1982. User's Instructions for the 
SHORTZ and LONGZ Computer Programs. EPA Publication No. EPA-903/9-82-
004a and b. U.S. Environmental Protection Agency, Region III, 
Philadelphia, PA.
    Businger, J.A., 1973. Turbulence Transfer in the Atmospheric Surface 
Layer. Workshop in Micrometeorology. American Meteorological Society, 
Boston, MA, pp. 67-100.
    Businger, J.A. and S.P. Arya, 1974. Height of the Mixed Layer in the 
Stably Stratified Planetary Boundary Layer. Advances in Geophysics, Vol. 
18A, F.N. Frankiel and R.E. Munn (Eds.), Academic Press, New York, NY.
    Catalano, J.A., 1986. Addendum to the User's Manual for the Single 
Source (CRSTER) Model. EPA Publication No. EPA-600/8-86-041. U.S. 
Environmental Protection Agency, Research Triangle Park, NC. (NTIS No. 
PB 87-145843)
    Environmental Protection Agency, 1980. Recommendations on Modeling 
(October 1980 Meetings). Appendix G to: Summary of Comments and 
Responses on the October 1980 Proposed Revisions to the Guideline on Air 
Quality Models. Meteorology and Assessment Division, Office of Research 
and Development, Research Triangle Park, NC.
    Gery, M.W., G.Z. Whitten and J.P. Killus, 1988. Development and 
Testing of CBM-IV for Urban and Regional Modeling. EPA Publication No. 
EPA-600/3-88-012. U.S. Environmental Protection Agency, Research 
Triangle Park, NC. (NTIS No. PB 88-180039)
    Gery, M.W., G.Z. Whitten, J.P. Killus and M.C. Dodge, 1989. A 
Photochemical Kinetics Mechanism for Urban and Regional Scale Computer 
Modeling. Journal of Geophysical Research, 94: 12,925-12,956.
    Gifford, F.A., Jr. 1976. Turbulent Diffusion Typing Schemes--A 
Review. Nuclear Safety, 17: 68-86.
    Horst, T.W., 1983. A Correction to the Gaussian Source-depletion 
Model. In Precipitation Scavenging, Dry Deposition and Resuspension. H. 
R. Pruppacher, R.G. Semonin and W.G.N. Slinn, eds., Elsevier, NY.
    Hsu, S.A., 1981. Models for Estimating Offshore Winds from Onshore 
Meteorological Measurements. Boundary Layer Meteorology, 20: 341-352.
    Huber, A.H. and W.H. Snyder, 1976. Building Wake Effects on Short 
Stack Effluents. Third Symposium on Atmospheric Turbulence, Diffusion 
and Air Quality, American Meteorological Society, Boston, MA.
    Irwin, J.S., 1979. A Theoretical Variation of the Wind Profile 
Power-Law Exponent as a Function of Surface Roughness and Stability. 
Atmospheric Environment, 13: 191-194.
    Lamb, R.G. et al., 1977. Continued Research in Mesoscale Air 
Pollution Simulation Modeling--Vol. VI: Further Studies in the Modeling 
of Microscale Phenomena, Report Number EF77-143. Systems Applications, 
Inc., San Rafael, CA.
    Liu, M.K. et al., 1976. The Chemistry, Dispersion, and Transport of 
Air Pollutants Emitted from Fossil Fuel Power Plants in California: Data 
Analysis and Emission Impact Model. Systems Applications, Inc., San 
Rafael, CA.
    Moore, G.E., T.E. Stoeckenius and D.A. Stewart, 1982. A Survey of 
Statistical Measures of Model Performance and Accuracy for Several Air 
Quality Model. EPA Publication No. EPA-450/4-83-001. U.S. Environmental 
Protection Agency, Research Triangle Park, NC.
    Pasquill, F., 1976. Atmospheric Dispersion Parameters in Gaussian 
Plume Modeling Part II. Possible Requirements for Change in the Turner 
Workbook Values. EPA Publication No. EPA-600/4-76-030b. U.S. 
Environmental Protection Agency, Research Triangle Park, NC.
    Petersen, W.B., 1980. User's Guide for HIWAY-2 A Highway Air 
Pollution Model. EPA Publication No. EPA-600/8-80-018. U.S. 
Environmental Protection Agency, Research Triangle Park, NC. (NTIS PB 
80-227556)
    Rao, T.R. and M.T. Keenan, 1980. Suggestions for Improvement of the 
EPA-HIWAY Model. Journal of the Air Pollution Control Association, 30: 
247-256 (and reprinted as Appendix C in Petersen, 1980).
    Segal, H.M., 1983. Microcomputer Graphics in Atmospheric Dispersion 
Modeling. Journal of the Air Pollution Control Association, 23: 598-600.
    Turner, D.B., 1969. Workbook of Atmospheric Dispersion Estimates. 
PHS Publication No. 999-26. U.S. Environmental Protection Agency, 
Research Triangle, Park, NC.
    Weil, J.C. and R.P. Brower, 1984. An Updated Gaussian Plume Model 
for Tall Stacks. Journal of the Air Pollution Control Association, 34: 
818-827.

   Appendix B to Appendix W of Part 51--Summaries of Alternative Air 
                             Quality Models

                            Table of Contents

B.0 Introduction and Availability
B.1 AVACTA II Model
B.2 Dense Gas Dispersion Model (DEGADIS)

[[Page 449]]

B.3 ERT Visibility Model
B.4 HGSYSTEM
B.5 HOTMAC/RAPTAD
B.6 LONGZ
B.7 Maryland Power Plant Siting Program (PPSP) Model
B.8 Mesoscale Puff Model (MESOPUFF II)
B.9 Mesoscale Transport Diffusion and Deposition Model For Industrial 
          Sources (MTDDIS)
B.10 Multi-Source (SCSTER) Model
B.11 PANACHE
B.12 PLUME Visibility Model (PLUVUE II)
B.13 Point, Area, Line Source Algorithm (PAL-DS)
B.14 Reactive Plume Model (RPM-IV)
B.15 Shoreline Dispersion Model (SDM)
B.16 SHORTZ
B.17 Simple Line-Source Model
B.18 SLAB
B.19 WYNDvalley Model
B.REF References

                    B.0 Introduction and Availability

    This appendix summarizes key features of refined air quality models 
that may be considered on a case-by-case basis for individual regulatory 
applications. For each model, information is provided on availability, 
approximate cost, regulatory use, data input, output format and options, 
simulation of atmospheric physics and accuracy. The models are listed by 
name in alphabetical order.
    There are three separate conditions under which these models will 
normally be approved for use:
    1. A demonstration can be made that the model produces concentration 
estimates equivalent to the estimates obtained using a preferred model 
(e.g., the maximum or high, second-high concentration is within 2% of 
the estimate using the comparable preferred model);
    2. A statistical performance evaluation has been conducted using 
measured air quality data and the results of that evaluation indicate 
the model in appendix B performs better for the application than a 
comparable model in appendix A; and
    3. There is no preferred model for the specific application but a 
refined model is needed to satisfy regulatory requirements.
    Any one of these three separate conditions may warrant use of these 
models. See section 3.2, Use of Alternative Models, for additional 
details.
    Many of these models have been subject to a performance evaluation 
by comparison with observed air quality data. A summary of such 
comparisons for models contained in this appendix is included in Moore 
et al. (1982). Where possible, several of the models contained herein 
have been subjected to rigorous evaluation exercises, including (1) 
statistical performance measures recommended by the American 
Meteorological Society and (2) peer scientific reviews.
    A source for some of these models and user's documentation is: 
Computer Products, National Technical Information Service (NTIS), U.S. 
Department of Commerce, Springfield, VA 22161, Phone: (703) 487-4650. A 
number of the model codes and selected, abridged user's guides are also 
available from the Support Center for Regulatory Air Models Bulletin 
Board System19 (SCRAM BBS), Telephone (919) 541-5742. The 
SCRAM BBS is an electronic bulletin board system designed to be user 
friendly and accessible from anywhere in the country. Model users with 
personal computers are encouraged to use the SCRAM BBS to download 
current model codes and text files.

                           B.1 AVACTA II Model

                                Reference

    Zannetti, P., G. Carboni and R. Lewis, 1985. AVACTA II User's Guide 
(Release 3). AeroVironment, Inc., Technical Report AV-OM-85/520.

                              Availability

    A 3\1/2\'' diskette of the FORTRAN coding and the user's guide are 
available at a cost of $3,500 (non-profit organization) or $5,000 (other 
organizations) from: AeroVironment, Inc., 222 Huntington Drive, 
Monrovia, CA 91016, Phone: (818) 357-9983.

                                Abstract

    The AVACTA II model is a Gaussian model in which atmospheric 
dispersion phenomena are described by the evolution of plume elements, 
either segments or puffs. The model can be applied for short time (e.g., 
one day) simulations in both transport and calm conditions.
    The user is given flexibility in defining the computational domain, 
the three-dimensional meteorological and emission input, the receptor 
locations, the plume rise formulas, the sigma formulas, etc. Without 
explicit user's specifications, standard default values are assumed.
    AVACTA II provides both concentration fields on the user specified 
receptor points, and dry/wet deposition patterns throughout the domain. 
The model is particularly oriented to the simulation of the dynamics and 
transformation of sulfur species (SO2 and 
SO4=), but can handle virtually any pair of 
primary-secondary pollutants.

                  a. Recommendations for Regulatory Use

    AVACTA II can be used if it can be demonstrated to estimate 
concentrations equivalent to those provided by the preferred model for a 
given application. AVACTA II must be executed in the equivalent mode.
    AVACTA II can be used on a case-by-case basis in lieu of a preferred 
model if it can be demonstrated, using the criteria in section

[[Page 450]]

3.2, that AVACTA II is more appropriate for the specific application. In 
this case the model options/modes which are most appropriate for the 
application should be used.

                          b. Input Requirements

    A time-varying input is required at each computational step. Only 
those data which have changed need to be input by the user.
    Source data requirements are: Coordinates, emission rates of primary 
and secondary pollutants, initial plume sigmas (for non-point sources), 
exit temperature, exit velocity, stack inside diameter.
    Meteorological data requirements are: surface wind measurements, 
wind profiles (if available), atmospheric stability profiles, mixing 
heights.
    Receptor data requirements are: receptor coordinates.
    Other data requirements: coordinates of the computational domain, 
grid cell specification, terrain elevations, user's computational and 
printing options.

                                c. Output

    The model's output is provided according to user's printing flags. 
Hourly, 3-hour and 24-hour concentration averages are computed, together 
with highest and highest-second-highest concentration values. Both 
partial and total concentrations are provided.

                            d. Type of Model

    AVACTA II is Gaussian segment/puff model.

                           e. Pollutant Types

    AVACTA II can handle any couple of primary-secondary pollutants 
(e.g., SO2 and SO4=).

                     f. Source Receptor Relationship

    The AVACTA II approach maintains the basic Gaussian formulation, but 
allows a numerical simulation of both nonstationary and nonhomogeneous 
meteorological conditions. The emitted pollutant material is divided 
into a sequence of ``elements,'' either segments or puffs, which are 
connected together but whose dynamics are a function of the local 
meteorological conditions. Since the meteorological parameters vary with 
time and space, each element evolves according to the different 
meteorological conditions encountered along its trajectory.
    AVACTA II calculates the partial contribution of each source in each 
receptor during each interval. The partial concentration is the sum of 
the contribution of all existing puffs, plus that of the closest 
segment.

                            g. Plume Behavior

    The user can select the following plume rise formulas:
    Briggs (1969, 1971, 1972)
    CONCAWE (Briggs, 1975)
    Lucas-Moore (Briggs, 1975)
    User's function, i.e., a subroutine supplied by the user
    With cold plumes, the program uses a special routine for the 
computation of the jet plume rise. The user can also select several 
computational options that control plume behavior in complex terrain and 
its total/partial reflections.

                           h. Horizontal Winds

    A 3D mass-consistent wind field is optionally generated.

                         i. Vertical Wind Speed

    A 3D mass-consistent wind field is optionally generated.

                        j. Horizontal Dispersion

    During each step, the sigmas of each element are increased. The user 
can select the following sigma functions:
    Pasquill-Gifford-Turner (in the functional form specified by Green 
et al., 1980)
    Brookhaven (Gifford, 1975)
    Briggs, open country (Gifford, 1975)
    Briggs, urban, i.e., McElroy-Pooler (Gifford, 1975)
    Irwin (1979a)
    LO-LOCAT (MacCready et al., 1974)
    User-specified function, by points
    User-specified function, with a user's subroutine
    The virtual distance/age concept is used for incrementing the sigmas 
at each time step.

                         k. Vertical Dispersion

    During each step, the sigmas of each element are increased. The user 
can select the following sigma functions:
    Pasquill-Gifford-Turner (in the functional form specified by Green 
et al., 1980)
    Brookhaven (Gifford, 1975)
    Briggs, open country (Gifford, 1975)
    Briggs, urban, i.e., McElroy-Pooler (Gifford, 1975)
    LO-LOCAT (MacCready et al., 1974)
    User-specified function, with a user's subroutine
    The virtual distance/age concept is used for incrementing the sigmas 
at each time step.

                       l. Chemical Transformation

    First order chemical reactions (primary-to-secondary pollutant)

                           m. Physical Removal

    First order dry and wet deposition schemes

                          n. Evaluation Studies

    Zannetti P., G. Carboni and A. Ceriani, 1985. AVACTA II Model 
Simulations of Worst-Case Air Pollution Scenarios in

[[Page 451]]

Northern Italy. 15th International Technical Meeting on Air Pollution 
Modeling and Its Application, St. Louis, Missouri, April 15-19.

                B.2 Dense Gas Dispersion Model (DEGADIS)

                                Reference

    Environmental Protection Agency, 1989. User's Guide for the DEGADIS 
2.1--Dense Gas Dispersion Model. EPA Publication No. EPA-450/4-89-019. 
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. 
(NTIS No. PB 90-213893)

                              Availability

    The model code is only available on the Support Center for 
Regulatory Air Models Bulletin Board System (see section B.0).

                                Abstract

    DEGADIS 2.1 is a mathematical dispersion model that can be used to 
model the transport of toxic chemical releases into the atmosphere. Its 
range of applicability includes continuous, instantaneous, finite 
duration, and time-variant releases; negatively-buoyant and neutrally-
buoyant releases; ground-level, low-momentum area releases; ground-level 
or elevated upwardly-directed stack releases of gases or aerosols. The 
model simulates only one set of meteorological conditions, and therefore 
should not be considered applicable over time periods much longer than 1 
or 2 hours. The simulations are carried out over flat, level, 
unobstructed terrain for which the characteristic surface roughness is 
not a significant fraction of the depth of the dispersion layer. The 
model does not characterize the density of aerosol-type releases; 
rather, the user must assess that independently prior to the simulation.

                  a. Recommendations for Regulatory Use

    DEGADIS can be used as a refined modeling approach to estimate 
short-term ambient concentrations (1-hour or less averaging times) and 
the expected area of exposure to concentrations above specified 
threshold values for toxic chemical releases. The model is especially 
useful in situations where density effects are suspected to be important 
and where screening estimates of ambient concentrations are above levels 
of concern.

                          b. Input Requirements

    Data may be input directly from an external input file or via 
keyboard using an interactive program module. The model is not set up to 
accept real-time meteorological data or convert units of input values. 
Chemical property data must be input by the user. Such data for a few 
selected species are available within the model. Additional data may be 
added to this data base by the user.
    Source data requirements are: emission rate and release duration; 
emission chemical and physical properties (molecular weight, density vs. 
concentration profile in the case of aerosol releases, and contaminant 
heat capacity in the case of a nonisothermal gas release; stack 
parameters (i.e., diameter, elevation above ground level, temperature at 
release point).
    Meteorological data requirements are: wind speed at designated 
height above ground, ambient temperature and pressure, surface 
roughness, relative humidity, and ground surface temperature (which in 
most cases can be adequately approximated by the ambient temperature).
    Receptor data requirements are: averaging time of interest, above-
ground height of receptors, and maximum distance between receptors 
(since the model computes downwind receptor distances to optimize model 
performance, this parameter is used only for nominal control of the 
output listing, and is of secondary importance). No indoor 
concentrations are calculated by the model.

                                c. Output

    Printed output includes in tabular form:
     Listing of model input data;
     Plume centerline elevation, mole fraction, concentration, 
density, and temperature at each downwind distance;
     y and z values at 
each downwind distance;
     Off-centerline distances to 2 specified concentration 
values at a specified receptor height at each downwind distance (these 
values can be used to draw concentration isopleths after model 
execution);
     Concentration vs. time histories for finite-duration 
releases (if specified by user).
    The output print file is automatically saved and must be sent to the 
appropriate printer by the user after program execution.
    No graphical output is generated by the current version of this 
program.

                            d. Type of Model

    DEGADIS estimates plume rise and dispersion for vertically-upward 
jet releases using mass and momentum balances with air entrainment based 
on laboratory and field-scale data. These balances assume Gaussian 
similarity profiles for velocity, density, and concentration within the 
jet. Ground-level denser-than-air phenomena is treated using a power law 
concentration distribution profile in the vertical and a hybrid top hat-
Gaussian concentration distribution profile in the horizontal. A power 
law specification is used for the vertical wind profile. Ground-level 
cloud slumping phenomena and air entrainment are based on laboratory 
measurements and field-scale observations.

[[Page 452]]

                           e. Pollutant Types

    Neutrally- or negatively-buoyant gases and aerosols. Pollutants are 
assumed to be non-reactive and non-depositing.

                    f. Source-Receptor Relationships

    Only one source can be modeled at a time.
    There is no limitation to the number of receptors; the downwind 
receptor distances are internally-calculated by the model. The DEGADIS 
calculation is carried out until the plume centerline concentration is 
50% below the lowest concentration level specified by the user.
    The model contains no modules for source calculations or release 
characterization.

                            g. Plume Behavior

    Jet/plume trajectory is estimated from mass and momentum balance 
equations. Surrounding terrain is assumed to be flat, and stack tip 
downwash, building wake effects, and fumigation are not treated.

                           h. Horizontal Winds

    Constant logarithmic velocity profile which accounts for stability 
and surface roughness is used.
    The wind speed profile exponent is determined from a least squares 
fit of the logarithmic profile from ground level to the wind speed 
reference height. Calm winds can be simulated for ground-level low-
momentum releases.
    Along-wind dispersion of transient releases is treated using the 
methods of Colenbrander (1980) and Beals (1971).

                         i. Vertical Wind Speed

    Not treated.

                        j. Horizontal Dispersion

    When the plume centerline is above ground level, horizontal 
dispersion coefficients are based upon Turner (1969) and Slade (1968) 
with adjustments made for averaging time and plume density.
    When the plume centerline is at ground level, horizontal dispersion 
also accounts for entrainment due to gravity currents as parameterized 
from laboratory experiments.

                         k. Vertical Dispersion

    When the plume centerline is above ground level, vertical dispersion 
coefficients are based upon Turner (1969) and Slade (1968). Perfect 
ground reflection is applied.
    In the ground-level dense-gas regime, vertical dispersion is also 
based upon results from laboratory experiments in density-stratified 
fluids.

                       l. Chemical Transformation

    Not specifically treated.

                           m. Physical Removal

    Not treated.

                          n. Evaluation Studies

    Spicer, T.O. and J.A. Havens, 1986. Development of Vapor Dispersion 
Models for Nonneutrally Buoyant Gas Mixtures--Analysis of USAF/
N2O4 Test Data. USAF Engineering and Services 
Laboratory, Final Report ESL-TR-86-24.
    Spicer, T.O. and J.A. Havens, 1988. Development of Vapor Dispersion 
Models for Nonneutrally Buoyant Gas Mixtures--Analysis of TFI/
NH3 Test Data. USAF Engineering and Services Laboratory, 
Final Report.

                        o. Operating Information

    The model requires either a VAX computer or an IBM--
compatible PC for its execution. The model currently does not require 
supporting software. A FORTRAN compiler is required to generate program 
executables in the VAX computing environment. PC executables are 
provided within the source code; however, a PC FORTRAN compiler may be 
used to tailor a PC executable to the user's PC environment.

                        B.3 ERT Visibility Model

                                Reference

    ENSR Consulting and Engineering, 1990. ERT Visibility Model: Version 
4; Technical Description and User's Guide. Document M2020-003. ENSR 
Consulting and Engineering, 35 Nagog Park, Acton, MA 01720.

                              Availability

    The user's guide and model code on diskette are available as a 
package (as PB 96-501978) from the National Technical Information 
Service (see section B.0).

                                Abstract

    The ERT Visibility Model is a Gaussian dispersion model designed to 
estimate visibility impairment for arbitrary lines of sight due to 
isolated point source emissions by simulating gas-to-particle 
conversion, dry deposition, NO to NO2 conversion and linear 
radiative transfer.

                  a. Recommendations for Regulatory Use

    There is no specific recommendation at the present time. The ERT 
Visibility Model may be used on a case-by-case basis.

                          b. Input Requirements

    Source data requirements are: stack height, stack temperature, 
emissions of SO2, NOX, TSP, fraction of 
NOX as NO2, fraction of TSP which is carbonaceous, 
exit velocity, and exit radius.
    Meteorological data requirements are: hourly ambient temperature, 
mixing depth,

[[Page 453]]

wind speed at stack height, stability class, potential temperature 
gradient, and wind direction.
    Receptor data requirements are: observer coordinates with respect to 
source, latitude, longitude, time zone, date, time of day, elevation, 
relative humidity, background visual range, line-of-sight azimuth and 
elevation angle, inclination angle of the observed object, distance from 
observer to object, object and surface reflectivity, number and spacing 
of integral receptor points along line of sight.
    Other data requirements are: ambient concentrations of O3 
and NOX, deposition velocity of TSP, sulfate, nitrate, 
SO2 and NOX, first-order transformation rate for 
sulfate and nitrate.

                                c. Output

    Printed output includes both summary and detailed results as 
follows: Summary output: Page 1--site, observer and object parameters; 
Page 2--optical pollutants and associated extinction coefficients; Page 
3--plume model input parameters; Page 4--total calculated visual range 
reduction, and each pollutant's contribution; Page 5--calculated plume 
contrast, object contrast and object contrast degradation at the 550nm 
wavelength; Page 6--calculated blue/red ratio and E (U*V*W*) 
values for both sky and object discoloration.
    Detailed output: phase functions for each pollutant in four 
wavelengths (400, 450, 550, 650nm), concentrations for each pollutant 
along sight path, solar geometry contrast parameters at all wavelengths, 
intensities, tristimulus values and chromaticity coordinates for views 
of the object, sun, background sky and plume.

                            d. Type of Model

    ERT Visibility model is a Gaussian plume model for estimating 
visibility impairment.

                           e. Pollutant Types

    Optical activity of sulfate, nitrate (derived from SO2 
and NOX emissions), primary TSP and NO2 is 
simulated.

                     f. Source Receptor Relationship

    Single source and hour is simulated. Unlimited number of lines-of-
sight (receptors) is permitted per model run.

                            g. Plume Behavior

    Briggs (1971) plume rise equations for final rise are used.

                        h. Horizontal Wind Field

    A single wind speed and direction is specified for each case study. 
The wind is assumed to be spatially uniform.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Rural dispersion coefficients from Turner (1969) are used.

                         k. Vertical Dispersion

    Rural dispersion coefficients from Turner (1969) are used. Mixing 
height is accounted for with multiple reflection handled by summation of 
series near the source, and Fourier representation farther downwind.

                       l. Chemical Transformation

    First order transformations of sulfates and nitrates are used.

                           m. Physical Removal

    Dry deposition is treated by the source depletion method.

                          n. Evaluation Studies

    Seigneur, C., R.W. Bergstrom and A.B. Hudischewskyj, 1982. 
Evaluation of the EPA PLUVUE Model and the ERT Visibility Model Based on 
the 1979 VISTTA Data Base. EPA Publication No. EPA-450/4-82-008. U.S. 
Environmental Protection Agency, Research Triangle Park, NC.
    White, W.H., C. Seigneur, D.W. Heinold, M.W. Eltgroth, L.W. 
Richards, P.T. Roberts, P.S. Bhardwaja, W.D. Conner and W.E. Wilson, 
Jr., 1985. Predicting the Visibility of Chimney Plumes: An Inter-
comparison of Four Models with Observations at a Well-Controlled Power 
Plant. Atmospheric Environment, 19: 515-528.

                              B.4 HGSYSTEM

    (Dispersion Models for Ideal Gases and Hydrogen Fluoride)

                                Reference

    Post, L. (ed.), 1994. HGSYSTEM 3.0 Technical Reference Manual. Shell 
Research Limited, Thornton Research Centre, Chester, United Kingdom. 
(TNER 94.059)
    Post, L., 1994. HGSYSTEM 3.0 User's Manual. Shell Research Limited, 
Thornton Research Centre, Chester, United Kingdom. (TNER 94.059)

                              Availability

    The PC-DOS version of the HGSYSTEM software (HGSYSTEM: Version 3.0, 
Programs for modeling the dispersion of ideal gas and hydrogen fluoride 
releases, executable programs and source code can be installed from 
diskettes. These diskettes and all documentation are available as a 
package from API [(202) 682-8340] or from NTIS as PB 96-501960 (see 
section B.0).

[[Page 454]]

                           Technical Contacts

    Doug N. Blewitt, AMOCO Corporation, 1670 Broadway/MC 2018, Denver, 
CO, 80201, (303) 830-5312.
    Howard J. Feldman, American Petroleum Institute, 1220 L Street 
Northwest, Washington, DC 20005, (202) 682-8340.

                                Abstract

    HGSYSTEM is a PC-based software package consisting of mathematical 
models for estimating of one or more consecutive phases between spillage 
and near-field and far-field dispersion of a pollutant. The pollutant 
can be either a two-phase, multi-compound mixture of non-reactive 
compounds or hydrogen fluoride (HF) with chemical reactions. The 
individual models are:
    Database program:
    DATAPROP Generates physical properties used in other HGSYSTEM models
    Source term models:
    SPILL Transient liquid release from a pressurized vessel
    HFSPILL SPILL version specifically for HF
    LPOOL Evaporating multi-compound liquid pool model
    Near-field dispersion models:
    AEROPLUME High-momentum jet dispersion model
    HFPLUME AEROPLUME version specifically for HF
    HEGABOX Dispersion of instantaneous heavy gas releases
    Far-field dispersion models:
    HEGADAS(S,T) Heavy gas dispersion (steady-state and transient 
version)
    PGPLUME Passive Gaussian dispersion
    Utility programs:
    HFFLASH Flashing of HF from pressurized vessel
    POSTHS/POSTHT Post-processing of HEGADAS(S,T) results
    PROFILE Post-processor for concentration contours of airborne plumes
    GET2COL Utility for data retrieval
    The models assume flat, unobstructed terrain. HGSYSTEM can be used 
to model steady-state, finite-duration, instantaneous and time dependent 
releases, depending on the individual model used. The models can be run 
consecutively, with relevant data being passed on from one model to the 
next using link files. The models can be run in batch mode or using an 
iterative utility program.

                  a. Recommendations for Regulatory Use

    HGSYSTEM can be used as a refined model to estimate short-term 
ambient concentrations. For toxic chemical releases (non-reactive 
chemicals or hydrogen fluoride; 1-hour or less averaging times) the 
expected area of exposure to concentrations above specified threshold 
values can be determined. For flammable non-reactive gases it can be 
used to determine the area in which the cloud may ignite.

                          b. Input Requirements

    HFSPILL input data: reservoir data (temperature, pressure, volume, 
HF mass, mass-fraction water), pipe-exit diameter and ambient pressure.
    EVAP input data: spill rate, liquid properties, and evaporation rate 
(boiling pool) or ambient data (non-boiling pool).
    HFPLUME and PLUME input data: reservoir characteristics, pollutant 
parameters, pipe/release data, ambient conditions, surface roughness and 
stability class.
    HEGADAS input data: ambient conditions, pollutant parameters, pool 
data or data at transition point, surface roughness, stability class and 
averaging time.
    PGPLUME input data: link data provided by HFPLUME and the averaging 
time.

                                c. Output

    The HGSYSTEM models contain three post-processor programs which can 
be used to extract modeling results for graphical display by external 
software packages. GET2COL can be used to extract data from the model 
output files. HSPOST can be used to develop isopleths, extract any 2 
parameters for plotting and correct for finite release duration. HTPOST 
can be used to produce time history plots.
    HFSPILL output data: reservoir mass, spill rate, and other reservoir 
variables as a function of time. For HF liquid, HFSPILL generates link 
data to HFPLUME for the initial phase of choked liquid flow (flashing 
jet), and link data to EVAP for the subsequent phase of unchoked liquid 
flow (evaporating liquid pool).
    EVAP output data: pool dimensions, pool evaporation rate, pool mass 
and other pool variables for steady state conditions or as a function of 
time. EVAP generates link data to the dispersion model HEGADAS (pool 
dimensions and pool evaporation rate).
    HFPLUME and PLUME output data: plume variables (concentration, 
width, centroid height, temperature, velocity, etc.) as a function of 
downwind distance.
    HEGADAS output data: concentration variables and temperature as a 
function of downwind distance and (for transient case) time.
    PGPLUME output data: concentration as a function of downwind 
distance, cross-wind distance and height.

                            d. Type of Model

    HGSYSTEM is made up of four types of dispersion models. HFPLUME and 
PLUME simulate the near-field dispersion and PGPLUME simulates the 
passive-gas dispersion downwind of a transition point.

[[Page 455]]

HEGADAS simulates the ground-level heavy-gas dispersion.

                           e. Pollutant Types

    HGSYSTEM may be used to model non-reactive chemicals or hydrogen 
fluoride.

                    f. Source-Receptor Relationships

    HGSYSTEM estimates the expected area of exposure to concentrations 
above user-specified threshold values. By imposing conservation of mass, 
momentum and energy the concentration, density, speed and temperature 
are evaluated as a function of downwind distance.

                            g. Plume Behavior

    HFPLUME and PLUME: (1) are steady-state models assuming a top-hat 
profile with cross-section averaged plume variables; and (2) the 
momentum equation is taken into account for horizontal ambient shear, 
gravity, ground collision, gravity-slumping pressure forces and ground-
surface drag.
    HEGADAS: assumes the heavy cloud to move with the ambient wind 
speed, and adopts a power-law fit of the ambient wind speed for the 
velocity profile.
    PGPLUME: simulates the passive-gas dispersion downwind of a 
transition point from HFPLUME or PLUME for steady-state and finite 
duration releases.

                           h. Horizontal Winds

    A power law fit of the ambient wind speed is used.

                         i. Vertical Wind Speed

    Not treated.

                        j. Horizontal Dispersion

    HFPLUME and PLUME: Plume dilution is caused by air entrainment 
resulting from high plume speeds, trailing vortices in wake of falling 
plume (before touchdown), ambient turbulence and density stratification. 
Plume dispersion is assumed to be steady and momentum-dominated, and 
effects of downwind diffusion and wind meander (averaging time) are not 
taken into account.
    HEGADAS: This model adopts a concentration similarity profile 
expressed in terms of an unknown center-line ground-level concentration 
and unknown vertical/cross-wind dispersion parameters. These quantities 
are determined from a number of basic equations describing gas-mass 
conservation, air entrainment (empirical law describing vertical top-
entrainment in terms of global Richardson number), cross-wind gravity 
spreading (initial gravity spreading followed by gravity-current 
collapse) and cross-wind diffusion (Briggs formula).
    PGPLUME: This model assumes a Gaussian concentration profile in 
which the cross-wind and vertical dispersion coefficients are determined 
by empirical expressions. All unknown parameters in this profile are 
determined by imposing appropriate matching criteria at the transition 
point.

                         k. Vertical Dispersion

    See description above.

                       l. Chemical Transformation

    Not treated.

                           m. Physical Removal

    Not treated.

                          n. Evaluation Studies

    PLUME has been validated against field data for releases of 
liquified propane, and wind tunnel data for buoyant and vertically-
released dense plumes. HFPLUME and PLUME have been validated against 
field data for releases of HF (Goldfish experiments) and propane 
releases. In addition, the plume rise algorithms have been tested 
against Hoot, Meroney, and Peterka, Ooms and Petersen databases. HEGADAS 
has been validated against steady and transient releases of liquid 
propane and LNG over water (Maplin Sands field data), steady and finite-
duration pressurized releases of HF (Goldfish experiments; linked with 
HFPLUME), instantaneous release of Freon (Thorney Island field data; 
linked with the box model HEGABOX) and wind tunnel data for steady, 
isothermal dispersion.
    Validation studies are contained in the following references.
    McFarlane, K., Prothero, A., Puttock, J.S., Roberts, P.T. and H.W.M. 
Witlox, 1990. Development and validation of atmospheric dispersion 
models for ideal gases and hydrogen fluoride, Part I: Technical 
Reference Manual. Report TNER.90.015. Thornton Research Centre, Shell 
Research, Chester, England. [EGG 1067-1151] (NTIS No. DE 93-000953)
    Witlox, H.W.M., McFarlane, K., Rees, F.J. and J.S. Puttock, 1990. 
Development and validation of atmospheric dispersion models for ideal 
gases and hydrogen fluoride, Part II: HGSYSTEM Program User's Manual. 
Report TNER.90.016. Thornton Research Centre, Shell Research, Chester, 
England. [EGG 1067-1152] (NTIS No. DE 93-000954)

                            B.5 HOTMAC/RAPTAD

                                Reference

    Mellor, G.L. and T. Yamada, 1974. A Hierarchy of Turbulence Closure 
Models for Planetary Boundary Layers. Journal of Atmospheric Sciences, 
31: 1791-1806.
    Mellor, G.L. and T. Yamada, 1982. Development of a Turbulence 
Closure Model for Geophysical Fluid Problems. Rev. Geophys. Space Phys., 
20: 851-875.

[[Page 456]]

    Yamada, T. and S. Bunker, 1988. Development of a Nested Grid, Second 
Moment Turbulence Closure Model and Application to the 1982 ASCOT Brush 
Creek Data Simulation. Journal of Applied Meteorology, 27: 562-578.

                              Availability

    For a cost to be negotiated with the model developer, a \1/4\-inch 
data cartridge or a 4mm DAT tape containing the HOTMAC/RAPTAD computer 
codes including pre- and post-processors and hard copies of user manuals 
(User's Manual, Maintenance Manual, Operations Manual, Maintenance 
Interface Manual, Topo Manual, and 3-Dimensional Plume Manual) are 
available from YSA Corporation, Rt. 4 Box 81-A, Santa Fe, NM 87501; 
Phone: (505) 989-7351; Fax: (505) 989-7965; e-mail: [email protected]

                                Abstract

    YSA Corporation offers a comprehensive modeling system for 
environmental studies. The system includes a mesoscale meteorological 
code, a transport and diffusion code, and extensive Graphical User 
Interfaces (GUIs). This system is unique because the diffusion code uses 
time dependent, three-dimensional winds and turbulence distributions 
that are forecasted by a mesoscale weather prediction model. 
Consequently the predicted concentration distributions are more accurate 
than those predicted by traditional models when surface conditions are 
heterogeneous. In general, the modeled concentration distributions are 
not Gaussian because winds and turbulence distributions The models were 
originally developed by using super computers. However, recent 
advancement of computer hardware has made it possible to run complex 
three-dimensional meteorological models on desktop workstations. The 
present versions of the programs are running on super computers and 
workstations. GUIs are available on Sun Microsystems and Silicon 
Graphics workstations. The modeling system can also run on a laptop 
workstation which makes it possible to run the programs in the field or 
away from the office. As technology continues to advance, a version of 
HOTMAC/RAPTAD suitable for PC-based platforms will be considered for 
release by YSA.
    HOTMAC, Higher Order Turbulence Model for Atmospheric Circulation, 
is a mesoscale weather prediction model that forecasts wind, 
temperature, humidity, and atmospheric turbulence distributions over 
complex surface conditions. HOTMAC has options to include non-
hydrostatic pressure computation, nested grids, land-use distributions, 
cloud, fog, and precipitation physics. HOTMAC can interface with tower, 
rawinsonde, and large-scale weather data using a four-dimensional data 
assimilation method. RAPTAD, Random Puff Transport and Diffusion, is a 
Lagrangian random puff model that is used to forecast transport and 
diffusion of airborne materials over complex terrain. Concentrations are 
computed by summing the concentration of each puff at the receptor 
location. The random puff method is equivalent to the random particle 
method with a Gaussian kernel for particle distribution. The advantage 
of the puff method is the accuracy and speed of computation. The 
particle method requires the release of a large number of particles 
which could be computationally expensive. The puff method requires the 
release of a much less number of puffs, typically \1/10\ to \1/100\ of 
the number of particles required by the particle method.
    The averaging time for concentration estimates is variable from 5 
minutes to 15 minutes for each receptor. In addition to the 
concentration computation at the receptor sites, RAPTAD computes and 
graphically displays hourly concentration contours at the ground level. 
RAPTAD is applicable to point and area sources.
    The meteorological data produced from HOTMAC are used as input to 
RAPTAD. RAPTAD can forecast concentration distributions for neutrally 
buoyant gas, buoyant gas and denser-than-air gas. The models are 
significantly advanced in both their model physics and in their 
operational procedures. GUIs are provided to help the user prepare input 
files, run programs, and display the modeled results graphically in 
three dimensions.

                  a. Recommendation for Regulatory Use

    There are no specific recommendations at the present time. The 
HOTMAC/RAPTAD modeling system may be used on a case-by-case basis.

                          b. Input Requirements

    Meteorological Data: The modeling system is significantly different 
from the majority of regulatory models in terms of how meteorological 
data are provided and used in concentration simulations. Regulatory 
models use the wind data which are obtained directly from measurements 
or analyzed by using a simple constraint such as a mass conservation 
equation. Thus, the accuracy of the computation will depend 
significantly on the quantity and quality of the wind data. This 
approach is acceptable as long as the study area is flat and the 
simulation period is short. As the regulations become more stringent and 
more realistic surface conditions are required, a significantly large 
volume of meteorological data is required which could become very 
expensive.
    An alternative approach is to augment the measurements with 
predicted values from a mesoscale meteorological model. This is the 
approach we have taken here. This approach

[[Page 457]]

has several advantages over the conventional method. First, 
concentration computations use the model forecast wind while the 
conventional method extrapolates the observed winds. Extrapolation of 
wind data over complex terrain and for an extended period of time 
quickly loses its accuracy. Secondly, the number of stations for upper 
air soundings is typically limited from none to at most a few stations 
in the study area. The corresponding number in a mesoscale model is the 
number of grid points in the horizontal plane which is typically 50 X 
50. Consequently, concentration distributions using model forecasted 
winds would be much more accurate than those obtained by using winds 
which were extrapolated from the limited number of measurements.
    HOTMAC requires meteorological data for initialization and to 
provide boundary conditions if the boundary conditions change 
significantly with time. The minimum amount of data required to run 
HOTMAC is wind and potential temperature profiles at a single station. 
HOTMAC forecasts wind and turbulence distributions in the boundary layer 
through a set of model equations for solar radiation, heat energy 
balance at the ground, conservation of momentum, conservation of 
internal energy, and conservation of mass.
    Terrain Data: HOTMAC and RAPTAD use the digitized terrain data from 
the U.S. Geological Survey and the Defense Mapping Agency. Extraction of 
terrain data is greatly simplified by using YSA's GUI software called 
Topo. The user specifies the latitudes and longitudes of the southwest 
and northeast corner points of the study area. Then, Topo extracts the 
digitized elevation data within the area specified and converts from the 
latitudes and longitudes to the UTM (Universal Transverse Mercator) 
coordinates for up to three nested grids.
    Emission Data: Emission data requirements are emission rate, stack 
height, stack diameter, stack location, stack gas exit velocity, and 
stack buoyancy.
    Receptor Data: Receptor data requirements are names, location 
coordinates, and desired averaging time for concentration estimates, 
which is variable from 5 to 15 minutes.

                                c. Output

    HOTMAC outputs include hourly winds, temperatures, and turbulence 
variables at every grid point. Ancillary codes graphically display 
vertical profiles of wind, temperature, and turbulence variables at 
selected locations and wind vector distributions at specified heights 
above the ground. These codes also produce graphic files of wind 
direction projected on vertical cross sections.
    RAPTAD outputs include hourly values of surface concentration, time 
variations of mean and standard deviation of concentrations at selected 
locations, and coordinates of puff center locations. Ancillary codes 
produce color contour plots of surface concentration, time variations of 
mean concentrations and ratios of standard deviation to mean value at 
selected locations, and concentration distributions in the vertical 
cross sections. The averaging time of concentration at a receptor 
location is variable from 5 to 15 minutes. Color contour plots of 
surface concentration can be animated on the monitor to review time 
variations of high concentration areas.

                            d. Type of Model

    HOTMAC is a 3-dimensional Eulerian model for weather forecasting, 
and RAPTAD is a 3-dimensional Lagrangian random puff model for pollutant 
transport and diffusion.

                           e. Pollutant types

    RAPTAD may be used to model any inert pollutants, including dense 
and buoyant gases.

                     f. Source-Receptor Relationship

    Up to six point or area sources are specified and up to 50 sampling 
locations are selected. Source and receptor heights are specified by the 
user.

                            g. Plume Behavior

    Neutrally buoyant plumes are transported by mean and turbulence 
winds that are modeled by HOTMAC. Non-neutrally buoyant plume equations 
are based on Van Dop (1992). In general, plumes are non-Gaussian.

                           h. Horizontal Winds

    RAPTAD uses wind speed, wind direction, and turbulence on a gridded 
array that is supplied hourly by HOTMAC. Stability effect and mixed 
layer height are incorporated through the intensity of turbulence which 
is a function of stability. HOTMAC predicts turbulence intensity by 
solving a turbulence kinetic energy equation and a length scale 
equation. RAPTAD interpolates winds and turbulence at puff center 
locations every 10 seconds from the values on a gridded array. RAPTAD 
can also use the winds observed at towers and by rawinsondes.

                         i. Vertical Wind Speed

    RAPTAD uses vertical winds on a gridded array that are supplied 
hourly by HOTMAC. HOTMAC computes vertical wind either by solving an 
equation of motion for the vertical wind or a mass conservation 
equation. RAPTAD interpolates vertical winds at puff center locations 
every 10 seconds from the values on a gridded array.

[[Page 458]]

                        j. Horizontal Dispersion

    Horizontal dispersion is based on the standard deviations of 
horizontal winds that are computed by HOTMAC.

                         k. Vertical Dispersion

    Vertical dispersion is based on the standard deviations of vertical 
wind that are computed by HOTMAC.

                       l. Chemical Transformation

    HOTMAC can provide meteorological inputs to other models that handle 
chemical reactions, e.g., UAM.

                           m. Physical Removal

    Not treated.

                          n. Evaluation Studies

    Yamada, T., S. Bunker and M. Moss, 1992. A Numerical Simulation of 
Atmospheric Transport and Diffusion over Coastal Complex Terrain. 
Journal of Applied Meteorology, 31: 565-578.
    Yamada, T. and T. Henmi, 1994. HOTMAC: Model Performance Evaluation 
by Using Project WIND Phase I and II Data. Mesoscale Modeling of the 
Atmosphere, American Meteorological Society, Monograph 47, pp. 123-135.

                                B.6 LONGZ

                                Reference

    Bjorklund, J.R. and J.F. Bowers, 1982. User's Instructions for the 
SHORTZ and LONGZ Computer Programs, Volumes I and II, EPA Publication 
No. EPA-903/9-82-004. U.S. Environmental Protection Agency, Region III, 
Philadelphia, PA.

                              Availability

    The computer code is available on the Support Center for Regulatory 
Air Models Bulletin Board System and on diskette (as PB 96-501994) from 
the National Technical Information Service (see section B.0).

                                Abstract

    LONGZ utilizes the steady-state univariate Gaussian plume 
formulation for both urban and rural areas in flat or complex terrain to 
calculate long-term (seasonal and/or annual) ground-level ambient air 
concentrations attributable to emissions from up to 14,000 arbitrarily 
placed sources (stacks, buildings and area sources). The output consists 
of the total concentration at each receptor due to emissions from each 
user-specified source or group of sources, including all sources. An 
option which considers losses due to deposition (see the description of 
SHORTZ) is deemed inappropriate by the authors for complex terrain, and 
is not discussed here.

                  a. Recommendations for Regulatory Use

    LONGZ can be used if it can be demonstrated to estimate 
concentrations equivalent to those provided by the preferred model for a 
given application. LONGZ must be executed in the equivalent mode.
    LONGZ can be used on a case-by-case basis in lieu of a preferred 
model if it can be demonstrated, using the criteria in section 3.2 of 
appendix W, that LONGZ is more appropriate for the specific application. 
In this case the model options/modes which are most appropriate for the 
application should be used.

                          b. Input Requirements

    Source data requirements are: for point, building or area sources, 
location, elevation, total emission rate (optionally classified by 
gravitational settling velocity) and decay coefficient; for stack 
sources, stack height, effluent temperature, effluent exit velocity, 
stack radius (inner), emission rate, and ground elevation (optional); 
for building sources, height, length and width, and orientation; for 
area sources, characteristic vertical dimension, and length, width and 
orientation.
    Meteorological data requirements are: wind speed and measurement 
height, wind profile exponents, wind direction standard deviations 
(turbulent intensities), mixing height, air temperature, vertical 
potential temperature gradient.
    Receptor data requirements are: coordinates, ground elevation.

                                c. Output

    Printed output includes total concentration due to emissions from 
user-specified source groups, including the combined emissions from all 
sources (with optional allowance for depletion by deposition).

                            d. Type of Model

    LONGZ is a climatological Gaussian plume model.

                           e. Pollutant Types

    LONGZ may be used to model primary pollutants. Settling and 
deposition are treated.

                    f. Source-Receptor Relationships

    LONGZ applies user specified locations for sources and receptors. 
Receptors are assumed to be at ground level.

                            g. Plume Behavior

    Plume rise equations of Bjorklund and Bowers (1982) are used.
    Stack tip downwash (Bjorklund and Bowers, 1982) is included.
    All plumes move horizontally and will fully intercept elevated 
terrain.
    Plumes above mixing height are ignored.

[[Page 459]]

    Perfect reflection at mixing height is assumed for plumes below the 
mixing height.
    Plume rise is limited when the mean wind at stack height approaches 
or exceeds stack exit velocity.
    Perfect reflection at ground is assumed for pollutants with no 
settling velocity.
    Zero reflection at ground is assumed for pollutants with finite 
settling velocity.
    LONGZ does not simulate fumigation.
    Tilted plume is used for pollutants with settling velocity 
specified.
    Buoyancy-induced dispersion is treated (Briggs, 1972).

                           h. Horizontal Winds

    Wind field is homogeneous and steady-state.
    Wind speed profile exponents are functions of both stability class 
and wind speed. Default values are specified in Bjorklund and Bowers 
(1982).

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Pollutants are initially uniformly distributed within each wind 
direction sector. A smoothing function is then used to remove 
discontinuities at sector boundaries.

                         k. Vertical Dispersion

    Vertical dispersion is derived from input vertical turbulent 
intensities using adjustments to plume height and rate of plume growth 
with downwind distance specified in Bjorklund and Bowers (1982).

                       l. Chemical Transformation

    Chemical transformations are treated using exponential decay. Time 
constant is input by the user.

                           m. Physical Removal

    Gravitational settling and dry deposition of particulates are 
treated.

                          n. Evaluation Studies

    Bjorklund, J.R. and J.F. Bowers, 1982. User's Instructions for the 
SHORTZ and LONGZ Computer Programs, Volume I and II. EPA Publication No. 
EPA-903/9-82-004. U.S. Environmental Protection Agency, Region III, 
Philadelphia, PA.

          B.7 Maryland Power Plant Siting Program (PPSP) Model

                                Reference

    Brower, R., 1982. The Maryland Power Plant Siting Program (PPSP) Air 
Quality Model User's Guide. Ref. No. PPSP-MP-38. Prepared for Maryland 
Department of Natural Resources by Environmental Center, Martin Marietta 
Corporation, Baltimore, MD. (NTIS No. PB 82-238387)
    Weil, J.C. and R.P. Brower, 1982. The Maryland PPSP Dispersion Model 
for Tall Stacks. Ref. No. PPSP-MP-36. Prepared for Maryland Department 
of Natural Resources by Environmental Center, Martin Marietta 
Corporation, Baltimore, MD. (NTIS No. PB 82-219155)

                              Availability

    The model code and test data are available on diskette for a nominal 
cost to defray shipping and handling charges from: Mr. Roger Brower, 
Versar, Inc., 9200 Rumsey Road, Columbia, MD 21045; Phone: (410) 964-
9299.

                                Abstract

    PPSP is a Gaussian dispersion model applicable to tall stacks in 
either rural or urban areas, but in terrain that is essentially flat (on 
a scale large compared to the ground roughness elements). The PPSP model 
follows the same general formulation and computer coding as CRSTER, also 
a Gaussian model, but it differs in four major ways. The differences are 
in the scientific formulation of specific ingredients or ``sub-models'' 
to the Gaussian model, and are based on recent theoretical improvements 
as well as supporting experimental data. The differences are: (1) 
stability during daytime is based on convective scaling instead of the 
Turner criteria; (2) Briggs' dispersion curves for elevated sources are 
used; (3) Briggs plume rise formulas for convective conditions are 
included; and (4) plume penetration of elevated stable layers is given 
by Briggs' (1984) model.

                  a. Recommendations for Regulatory Use

    PPSP can be used if it can be demonstrated to estimate 
concentrations equivalent to those provided by the preferred model for a 
given application. PPSP must be executed in the equivalent mode.
    PPSP can be used on a case-by-case basis in lieu of a preferred 
model if it can be demonstrated, using the criteria in section 3.2 of 
appendix W, that PPSP is more appropriate for the specific application. 
In this case the model options/modes which are most appropriate for the 
application should be used.

                          b. Input Requirements

    Source data requirements are: emission rate (monthly rates 
optional), physical stack height, stack gas exit velocity, stack inside 
diameter, stack gas temperature.
    Meteorological data requirements are: hourly surface weather data 
from the EPA meteorological preprocessor program.

[[Page 460]]

Preprocessor output includes hourly stability class, wind direction, 
wind speed, temperature, and mixing height. Actual anemometer height (a 
single value) is also required. Wind speed profile exponents (one for 
each stability class) are required if on-site data are input.
    Receptor data requirements are: distance of each of the five 
receptor rings.

                                c. Output

    Printed output includes:
    Highest and second highest concentrations for the year at each 
receptor for averaging times of 1, 3, and 24-hours, plus a user-selected 
averaging time which may be 2, 4, 6, 8, or 12 hours;
    Annual arithmetic average at each receptor; and
    For each day, the highest 1-hour and 24-hour concentrations over the 
receptor field.

                            d. Type of Model

    PPSP is a Gaussian plume model.

                           e. Pollutant Types

    PPSP may be used to model primary pollutants. Settling and 
deposition are not treated.

                     f. Source-Receptor Relationship

    Up to 19 point sources are treated.
    All point sources are assumed at the same location.
    Unique stack height and stack exit conditions are applied for each 
source.
    Receptor locations are restricted to 36 azimuths (every 10 degrees) 
and five user-specified radial distances.

                            g. Plume Behavior

    Briggs (1975) final rise formulas for buoyant plumes are used. 
Momentum rise is not considered.
    Transitional or distance-dependent plume rise is not modeled.
    Penetration (complete, partial, or zero) of elevated inversions is 
treated with Briggs (1984) model; ground-level concentrations are 
dependent on degree of plume penetration.

                           h. Horizontal Winds

    Wind speeds are corrected for release height based on power law 
variation, with different exponents for different stability classes and 
variable reference height (7 meters is default). Wind speed power law 
exponents are 0.10, 0.15, 0.20, 0.25, 0.30, and 0.30 for stability 
classes A through F, respectively.
    Constant, uniform (steady-state) wind assumed within each hour.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Rural dispersion parameters are Briggs (Gifford, 1975), with 
stability class defined by u/w* during daytime, and by the method of 
Turner (1964) at night.
    Urban dispersion is treated by changing all stable cases to 
stability class D.
    Buoyancy-induced dispersion (Pasquill, 1976) is included (using 
/3.5).

                         k. Vertical Dispersion

    Rural dispersion parameters are Briggs (Gifford, 1975), with 
stability class defined by u/w* during daytime, and by the method of 
Turner (1964).
    Urban dispersion is treated by changing all stable cases to 
stability class D.
    Buoyancy-induced dispersion (Pasquill, 1976) is included (using 
/3.5).

                       l. Chemical Transformation

    Not treated.

                           m. Physical Removal

    Not treated.

                          n. Evaluation Studies

    Londergan, R., D. Minott, D. Wackter, T. Kincaid and D. Bonitata, 
1983. Evaluation of Rural Air Quality Simulation Models, Appendix G: 
Statistical Tables for PPSP. EPA Publication No. EPA-450/4-83-003. 
Environmental Protection Agency, Research Triangle Park, NC.
    Weil, J.C. and R.P. Brower, 1982. The Maryland PPSP dispersion model 
for tall stacks. Ref. No. PPSP MP-36. Prepared for Maryland Department 
of Natural Resources. Prepared by Environmental Center, Martin Marietta 
Corporation, Baltimore, Maryland. (NTIS No. PB 82-219155)

                 B.8 Mesoscale Puff Model (MESOPUFF II)

                                Reference

    Scire, J.S., F.W. Lurmann, A. Bass and S.R. Hanna, 1984. User's 
Guide to the Mesopuff II Model and Related Processor Programs. EPA 
Publication No. EPA-600/8-84-013. U.S. Environmental Protection Agency, 
Research Triangle Park, NC. (NTIS No. PB 84-181775)
    A Modeling Protocol for Applying MESOPUFF II to Long Range Transport 
Problems, 1992. EPA Publication No. EPA-454/R-92-021. U.S. Environmental 
Protection Agency, Research Triangle Park, NC.

                              Availability

    This model code is available on the Support Center for Regulatory 
Air Models Bulletin Board System and also on diskette (as PB 93-500247) 
from the National Technical Information Service (see section B.0).

[[Page 461]]

                                Abstract

    MESOPUFF II is a short term, regional scale puff model designed to 
calculate concentrations of up to 5 pollutant species (SO2, 
SO4, NOX, HNO3, NO3). 
Transport, puff growth, chemical transformation, and wet and dry 
deposition are accounted for in the model.

                  a. Recommendations for Regulatory Use

    There is no specific recommendation at the present time. The model 
may be used on a case-by-case basis.

                          b. Input Requirements

    Required input data include four types: (1) input control parameters 
and selected technical options, (2) hourly surface meteorological data 
and twice daily upper air measurements, hourly precipitation data are 
optional, (3) surface land use classification information, (4) source 
and emissions data.
    Data from up to 25 surface National Weather Service stations and up 
to 10 upper air stations may be considered. Spatially variable fields at 
hour intervals of winds, mixing height, stability class, and relevant 
turbulence parameters are derived by MESOPAC II, the meteorological 
preprocessor program described in the User Guide.
    Source and emission data for up to 25 point sources and/or up to 5 
area sources can be included. Required information are: location in grid 
coordinates, stack height, exit velocity and temperature, and emission 
rates for the pollutant to be modeled.
    Receptor data requirements: up to a 40 x 40 grid may be used and 
non-gridded receptor locations may be considered.

                                c. Output

    Line printer output includes: all input parameters, optionally 
selected arrays of ground-level concentrations of pollutant species at 
specified time intervals.
    Line printer contour plots output from MESOFILE II post-processor 
program. Computer readable output of concentration array to disk/tape 
for each hour.

                            d. Type of Model

    MESOPUFF II is a Gaussian puff superposition model.

                           e. Pollutant Types

    Up to five pollutant species may be modeled simultaneously and 
include: SO2, SO4, NOX, 
HNO3, NO3.

                     f. Source-Receptor Relationship

    Up to 25 point sources and/or up to 5 area sources are permitted.

                            g. Plume Behavior

    Briggs (1975) plume rise equations are used, including plume 
penetration with buoyancy flux computed in the model.
    Fumigation of puffs is considered and may produce immediate mixing 
or multiple reflection calculations at user option.

                           h. Horizontal Winds

    Gridded wind fields are computed for 2 layers; boundary layer and 
above the mixed layer. Upper air rawinsonde data and hourly surface 
winds are used to obtain spatially variable u,v component fields at 
hourly intervals. The gridded fields are computed by interpolation 
between stations in the MESOPAC II preprocessor.

                         i. Vertical Wind Speed

    Vertical winds are assumed to be zero.

                        j. Horizontal Dispersion

    Incremental puff growth is computed over discrete time steps with 
horizontal growth parameters determined from power law equations fit to 
sigma y curves of Turner out to 100km. At distances greater than 100km, 
puff growth is determined by the rate given by Heffter (1965).
    Puff growth is a function of stability class and changes in 
stability are treated. Optionally, user input plume growth coefficients 
may be considered.

                         k. Vertical Dispersion

    For puffs emitted at an effective stack height which is less than 
the mixing height, uniform mixing of the pollutant within the mixed 
layer is performed. For puffs centered above the mixing height, no 
effect at the ground occurs.

                       l. Chemical Transformation

    Hourly chemical rate constants are computed from empirical 
expressions derived from photochemical model simulations.

                           m. Physical Removal

    Dry deposition is treated with a resistance method.
    Wet removal may be considered if hourly precipitation data are 
input.

                          n. Evaluation Studies

    Results of tests for some model parameters are discussed in:
    Scire, J.S., F.W. Lurmann, A. Bass and S.R. Hanna, 1984. Development 
of the MESOPUFF II Dispersion Model. EPA Publication No. EPA-600/3-84-
057. U.S. Environmental Protection Agency, Research Triangle Park, NC.

[[Page 462]]

 B.9 Mesoscale Transport Diffusion and Deposition Model for Industrial 
                            Sources (MTDDIS)

                                Reference

    Wang, I.T. and T.L. Waldron, 1980. User's Guide for MTDDIS Mesoscale 
Transport, Diffusion, and Deposition Model for Industrial Sources. 
EMSC6062.1UR(R2). Combustion Engineering, Newbury Park, CA.

                              Availability

    A diskette copy of the FORTRAN coding and the user's guide are 
available for a cost of $100 from: Dr. I. T. Wang, Environmental 
Modeling & Analysis, 2219 E. Thousand Oaks Blvd., Suite 435, Thousand 
Oaks, CA 91362.

                                Abstract

    MTDDIS is a variable-trajectory Gaussian puff model applicable to 
long-range transport of point source emissions over level or rolling 
terrain. The model can be used to determine 3-hour maximum and 24-hour 
average concentrations of relatively nonreactive pollutants from up to 
10 separate stacks.

                  a. Recommendations for Regulatory Use

    There is no specific recommendation at the present time. The MTDDIS 
Model may be used on a case-by-case basis.

                          b. Input Requirements

    Source data requirements are: emission rate, physical stack height, 
stack gas exit velocity, stack inside diameter, stack gas temperature, 
and location.
    Meteorological data requirements are: hourly surface weather data, 
from up to 10 stations, including cloud ceiling, wind direction, wind 
speed, temperature, opaque cloud cover and precipitation. For long-range 
applications, user-analyzed daily mixing heights are recommended. If 
these are not available, the NWS daily mixing heights will be used by 
the program. A single upper air sounding station for the region is 
assumed. For each model run, air trajectories are generated for a 48-
hour period, and therefore, the afternoon mixing height of the day 
before and the mixing heights of the day after are also required by the 
model as input, in order to generate hourly mixing heights for the 
modeled period.
    Receptor data requirements are: up to three user-specified 
rectangular grids.

                                c. Output

    Printed output includes:
    Tabulations of hourly meteorological parameters include both input 
surface observations and calculated hourly stability classes and mixing 
heights for each station;
    Printed air trajectories for the two consecutive 24-hour periods for 
air parcels generated 4 hours apart starting at 0000 LST; and
    3-hour maximum and 24-hour average grid concentrations over user-
specified rectangular grids are output for the second 24-hour period.

                            d. Type of Model

    MTDDIS is a Gaussian puff model.

                           e. Pollutant Types

    MTDDIS can be used to model primary pollutants. Dry deposition is 
treated. Exponential decay can account for some reactions.

                     f. Source-Receptor Relationship

    MTDDIS treats up to 10 point sources.
    Up to three rectangular receptor grids may be specified by the user.

                            g. Plume Behavior

    Briggs (1971, 1972) plume rise formulas are used.
    If plume height exceeds mixing height, ground level concentration is 
assumed zero.
    Fumigation and downwash are not treated.

                           h. Horizontal Winds

    Wind speeds and wind directions at each station are first corrected 
for release height. Speed conversions are based on power law variation 
and direction conversions are based on linear height dependence as 
recommended by Irwin (1979b).
    Converted wind speeds and wind directions are then weighted 
according to the algorithms of Heffter (1980) to calculate the effective 
transport wind speed and direction.

                         i. Vertical Wind Field

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Transport-time-dependent dispersion coefficients from Heffter (1980) 
are used.

                         k. Vertical Dispersion

    Transport-time-dependent dispersion coefficients from Heffter (1980) 
are used.

                       l. Chemical Transformation

    Chemical transformations are treated using exponential decay. Half-
life is input by the user.

                           m. Physical Removal

    Dry deposition is treated. User input deposition velocity is 
required.
    Wet deposition is treated. User input hourly precipitation rate and 
precipitation layer depth or cloud ceiling height are required.

[[Page 463]]

                          n. Evaluation Studies

    Carhart, R.A., A.J. Policastro, M. Wastag and L. Coke, 1989. 
Evaluation of Eight Short-Term Long-Range Transport Models Using Field 
Data. Atmospheric Environment, 23: 85-105.

                    B.10 Multi-Source (SCSTER) Model

                                Reference

    Malik, M.H. and B. Baldwin, 1980. Program Documentation for Multi-
Source (SCSTER) Model. Program Documentation EN7408SS. Southern Company 
Services, Inc., Technical Engineering Systems, 64 Perimeter Center East, 
Atlanta, GA.

                              Availability

    The SCSTER model and user's manual are available at no charge on a 
limited basis through Southern Company Services. The computer code may 
be provided on a diskette. Requests should be directed to: Mr. Stanley 
S. Vasa, Senior Environmental Specialist, Southern Company Services, 
P.O. Box 2625, Birmingham, AL 35202.

                                Abstract

    SCSTER is a modified version of the EPA CRSTER model. The primary 
distinctions of SCSTER are its capability to consider multiple sources 
that are not necessarily collocated, its enhanced receptor 
specifications, its variable plume height terrain adjustment procedures 
and plume distortion from directional wind shear.

                  a. Recommendations for Regulatory Use

    SCSTER can be used if it can be demonstrated to estimate 
concentrations equivalent to those provided by the preferred model for a 
given application. SCSTER must be executed in the equivalent mode.
    SCSTER can be used on a case-by-case basis in lieu of a preferred 
model if it can be demonstrated, using the criteria in section 3.2 of 
appendix W, that SCSTER is more appropriate for the specific 
application. In this case the model options/modes which are most 
appropriate for the application should be used.

                          b. Input Requirements

    Source data requirements are: emission rate, stack gas exit 
velocity, stack gas temperature, stack exit diameter, physical stack 
height, elevation of stack base, and coordinates of stack location. The 
variable emission data can be monthly or annual averages.
    Meteorological data requirements are: hourly surface weather data 
from the EPA meteorological preprocessor program. Preprocessor output 
includes hourly stability class wind direction, wind speed, temperature, 
and mixing height. Actual anemometer height (a single value) is 
optional. Wind speed profile exponents (one for each stability class) 
are optional.
    Receptor data requirements are: cartesian coordinates and elevations 
of individual receptors; distances of receptor rings, with elevation of 
each receptor; receptor grid networks, with elevation of each receptor.
    Any combination of the three receptor input types may be used to 
consider up to 600 receptor locations.

                                c. Output

    Printed output includes:
    Highest and second highest concentrations for the year at each 
receptor for averaging times of 1-, 3-, and 24-hours, a user-selected 
averaging time which may be 2-12 hours, and a 50 high table for 1-, 3-, 
and 24-hours;
    Annual arithmetic average at each receptor; and the highest 1-hour 
and 24-hour concentrations over the receptor field for each day 
considered.
    Optional tables of source contributions of individual point sources 
at up to 20 receptor locations for each averaging period;
    Optional magnetic tape output in either binary or fixed block format 
includes:
    All 1-hour concentrations.
    Optional card/disk output includes for each receptor:
    Receptor coordinates; receptor elevation; highest and highest, 
second-highest, 1-, 3-, and 24-hour concentrations; and annual average 
concentration.

                            d. Type of Model

    SCSTER is a Gaussian plume model.

                           e. Pollutant Types

    SCSTER may be used to model primary pollutants. Settling and 
deposition are not treated.

                     f. Source-Receptor Relationship

    SCSTER can handle up to 60 separate stacks at varying locations and 
up to 600 receptors, including up to 15 receptor rings.
    User input topographic elevation for each receptor is used.

                            g. Plume Behavior

    SCSTER uses Briggs (1969, 1971, 1972) final plume rise formulas.
    Transitional plume rise is optional.
    SCSTER contains options to incorporate wind directional shear with a 
plume distortion method described in appendix A of the User's Guide.
    SCSTER provides four terrain adjustments including the CRSTER full 
terrain height adjustment and a user-input, stability-dependent plume 
path coefficient adjustment for receptors above stack height.

[[Page 464]]

                           h. Horizontal Winds

    Wind speeds are corrected for release height based on power law 
exponents from DeMarrais (1959), different exponents for different 
stability classes; default reference height of 7m. Default exponents are 
0.10, 0.15, 0.20, 0.25, 0.30, and 0.30 for stability classes A through 
F, respectively.
    Steady-state wind is assumed within a given hour.
    Optional consideration of plume distortion due to user-input, 
stability-dependent wind-direction shear gradients.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Rural dispersion coefficients from Turner (1969) are used.
    Six stability classes are used.

                         k. Vertical Dispersion

    Rural dispersion coefficients from Turner (1969) are used.
    Six stability classes are used.
    An optional test for plume height above mixing height before terrain 
adjustment is included.

                       l. Chemical Transformation

    Chemical transformations are treated using exponential decay. Half-
life is input by the user.

                           m. Physical Removal

    Physical removal is treated using exponential decay. Half-life is 
input by the user.

                          n. Evaluation Studies

    Londergan, R., D. Minott, D. Wackter, T. Kincaid and D. Bonitata, 
1983. Evaluation of Rural Air Quality Simulation Models. EPA Publication 
No. EPA-450/4-83-003. U.S. Environmental Protection Agency, Research 
Triangle Park, NC.

                              B.11 PANACHE

                                Reference

    Transoft Group, 1994. User's Guide of Fluidyn-PANACHE, a Three-
Dimensional Deterministic Simulation of Pollutants Dispersion Model for 
Complex Terrain; Cary, North Carolina.

                              Availability

    For a cost to be negotiated with the model developer, the computer 
code is available from: Transoft US, Inc., 818 Reedy Creek Road, Cary, 
NC 27513-3307; Phone: (919) 380-7500, Fax: (919) 380-7592.

                                Abstract

    PANACHE is an Eulerian (and Lagrangian for particulate matter), 3-
dimensional finite volume fluid mechanics code designed to simulate 
continuous and short-term pollution dispersion in the atmosphere, in 
simple or complex terrain. For single or multiple sources, pollutant 
emissions from stack, point, area, volume, general sources and distant 
sources are treated. The model automatically treats obstacles, effects 
of vegetation and water bodies, the effects of vertical temperature 
stratification on the wind and diffusion fields, and turbulent shear 
flows caused by atmospheric boundary layer or terrain effects. The code 
solves Navier Stokes equations in a curvilinear mesh espousing the 
terrain and obstacles. A 2nd order resolution helps keep the number of 
cells limited in case of shearing flow. An initial wind field is 
computed by using a Lagrangian multiplier to interpolate wind data 
collected on site. The mesh generator, the solver and the numerical 
schemes have been adopted for atmospheric flows with or without chemical 
reactions. The model code operates on any workstation or IBM--compatible 
PC (486 or higher). Gaussian and puff modes are available in PANACHE for 
fast, preliminary simulation.

                  a. Recommendations for Regulatory Use

    On a case-by-case basis, PANACHE may be appropriate for the 
following types of situations: industrial or urban zone on a flat or 
complex terrain, transport distance from a few meters to 50km, 
continuous releases with hourly, monthly or annual averaging times, 
chemically reactive or non-reactive gases or particulate emissions for 
stationary or roadway sources.

                          b. Input Requirements

    Data may be input directly from an external source (e.g., GIS file) 
or interactively. The model provides the option to use default values 
when input parameters are unavailable.
    PANACHE user environment integrates the pre- and post-processor with 
the solver. The calculations can be done interactively or in batch mode. 
An inverse scheme is provided to estimate missing data from a few 
measured values of the wind.
    Terrain data requirements:
     Location, surface roughness estimates, and altitude 
contours.
     Location and dimensions of obstacles, forests, fields, and 
water bodies.
    Source data requirements:
    For all types of sources, the exit temperature and plume mass flow 
rates and concentration of each of the pollutants are required. External 
sources require mass flow rate. For roadways, estimated traffic volume 
and vehicular emissions are required.

[[Page 465]]

    Meteorological data requirements:
    Hourly stability class, wind direction, wind speed, temperature, 
cloud cover, humidity, and mixing height data with lapse rate below and 
above it.
    Primary meteorological variables available from the National Weather 
Service can be processed using PCRAMMET (see section 9.3.3.2 of appendix 
W) to an input file.
    Data required at the domain boundary:
    Wind profile (uniform, log or power law), depending on the terrain 
conditions (e.g., residential area, forest, sea, etc.).
    Chemical source data requirements:
    A database of selected species with specific heats and molecular 
weights can be extended by the user. For heavy gases the database 
includes a compressibility coefficients table.
    Solar reflection:
    For natural convection simulation with low wind on a sunny day, 
approximate values of temperature for fields, forests, water bodies, 
shadows and their variations with the time of the day are determined 
automatically.

                                c. Output

    Printed output option: pollutant concentration at receptor points, 
and listing of input data (terrain, chemical, weather, and source data) 
with turbulence and precision control data.
    Graphical output includes: In 3-dimensional perspective or in any 
crosswind, downwind or horizontal plane: wind velocity, pollutant 
concentration, 3-dimensional isosurface. The profile of concentration 
can be obtained along any line on the terrain. The concentration 
contours can be either instantaneous or time integrated for the emission 
from a source or a source combination. A special utility is included to 
help prepare a report or a video animation. The user can select images, 
put in annotations, or do animation.

                            d. Type of Model

    The model uses an Eulerian (and Lagrangian for particulate matter) 
3-dimensional finite volume model solving full Navier-Stokes equations. 
The numerical diffusion is low with appropriate turbulence models for 
building wakes. A second order resolution may be sought to limit the 
diffusion. Gaussian and puff modes are available. The numerical scheme 
is self adaptive for the following situations:
     A curvilinear mesh or a chopped Cartesian mesh is generated 
automatically or manually;
     Thermal and gravity effects are simulated by full gravity 
(heavy gases), no gravity (well mixed light gases at ambient 
temperature), and Boussinesq approximation methods;
     K-diff, K-e or a boundary layer turbulence models are used 
for turbulence calculations. The flow behind obstacles such as 
buildings, is calculated by using a modified K-e.
     For heavy gases, a 3-dimensional heat conduction from the 
ground and a stratification model for heat exchange from the atmosphere 
are used (with anisotropic turbulence).
     If local wind data are available, an initial wind field 
with terrain effects can be computed using a Lagrangian multiplier, 
which substantially reduces computation time.

                           e. Pollutant Types

     Scavenging, Acid Rain: A module for water droplets 
traveling through a plume considers the absorption and de-absorption 
effects of the pollutants by the droplet. Evaporation and chemical 
reactions with gases are also taken into account.
     Visibility: Predicts plume visibility and surface 
deposition of aerosol.
     Particulate matter: Calculates settling and dry deposition 
of particles based on a Probability Density Function (PDF) of their 
diameters. The exchange of mass, momentum and heat between particles and 
gas is treated with implicit coupling procedures.
     Ozone formation and dispersion: The photochemical model 
computes ozone formation and dispersion at street level in the presence 
of sunlight.
     Roadway Pollutants: Accounts for heat and turbulence due to 
vehicular movement. Emissions are based on traffic volume and emission 
factors.
     Odor Dispersion: Identifies odor sources for waste water 
plants.
     Radon Dispersion: Simulates natural radon accumulation in 
valleys and mine environments.
    PANACHE may also be used in emergency planning and management for 
episodic emissions, and fire and soot spread in forested and urban areas 
or from combustible pools.

                     f. Source-Receptor Relationship

    Simultaneous use of multiple kinds of sources at user defined 
locations. Any number of user defined receptors can identify pollutants 
from each source individually.

                            g. Plume Behavior

    The options influencing the behavior are full gravity, Boussinesq 
approximation or no gravity.

[[Page 466]]

                           h. Horizontal Winds

    Horizontal wind speed approximations are made only at the boundaries 
based on National Weather Service data. Inside the domain of interest, 
full Navier-Stokes resolution with natural viscosity is used for 3-
dimensional terrain and temperature dependent wind field calculation.

                         i. Vertical Wind Speed

    Vertical wind speed approximations are made only at the boundaries 
based on National Weather Service data. The domain of interest is 
treated as for horizontal winds.

                        j. Horizontal Dispersion

    Diffusion is calculated using appropriate turbulence models. A 2nd 
order solution for shearing flow can be sought when the number of meshes 
is limited between obstacles.

                         k. Vertical Dispersion

    Dispersion by full gravity unless Boussinesq approximation or no 
gravity requested. Vertical dispersion is treated as above for 
horizontal dispersion.

                       l. Chemical Transformation

    PANCHEM, an atmospheric chemistry module for chemical reactions, is 
available. Photochemical reactions are used for tropospheric ozone 
calculations.

                           m. Physical Removal

    Physical removal is treated using dry deposition coefficients

                          n. Evaluation Studies

    Goldwire, H.C. Jr, T.G. McRae, G.W. Johnson, D.L. Hipple, R.P. 
Koopman, J.W. McClure, L.K. Morris and R.T. Cederhall, 1985. Desert 
Tortoise Series Data Report: 1983 Pressurized Ammonia Spills. UCID 
20562, Lawrence Livermore National Laboratory; Livermore, California.
    Green, S.R., 1992. Modeling Turbulent Air Flow in a Stand of Widely 
Spaced Trees, The PHOENICS Journal of Computational Fluid Dynamics and 
Its Applications, 5: 294-312.
    Gryning, S.E. and E. Lyck, 1984. Atmospheric Dispersion from 
Elevated Sources in an Urban Area: Comparison Between Tracer Experiments 
and Model Calculations. Journal of Climate and Applied Meteorology, 23: 
651-660.
    Havens, J., T. Spicer, H. Walker and T. Williams, 1995. Validation 
of Mathematical Models Using Wind-Tunnel Data Sets for Dense Gas 
Dispersion in the Presence of Obstacles. University of Arkansas, 8th 
International Symposium-Loss Prevention and Safety Promotion in the 
Process Industries; Antwerp, Belgium.
    McQuaid, J. (ed), 1985. Heavy Gas Dispersion Trials at Thorney 
Island. Proc. of a Symposium held at the University of Sheffield, Great 
Britain.
    Pavitskiy, N.Y., A.A. Yakuskin and S.V. Zhubrin, 1993. Vehicular 
Exhaust Dispersion Around Group of Buildings. The PHOENICS Journal of 
Computational Fluid Dynamics and Its Applications, 6: 270-285.
    Tripathi, S., 1994. Evaluation of Fluidyn-PANACHE on Heavy Gas 
Dispersion Test Case. Seminar on Evaluation of Models of Heavy Gas 
Dispersion Organized by European Commission; Mol, Belgium.

                 B.12 Plume Visibility Model (PLUVUE II)

                                Reference

    Environmental Protection Agency, 1992. User's Manual for the Plume 
Visibility Model, PLUVUE II (Revised). EPA Publication No. EPA-454/B-92-
008, (NTIS PB93-188233). U.S. Environmental Protection Agency, Research 
Triangle Park, NC.

                              Availability

    This model code is available on the Support Center for Regulatory 
Air Models Bulletin Board System and also on diskette (as PB 90-500778) 
from the National Technical Information Service (see section B.0).

                                Abstract

    The Plume Visibility Model (PLUVUE II) is used for estimating visual 
range reduction and atmospheric discoloration caused by plumes 
consisting of primary particles, nitrogen oxides and sulfur oxides 
emitted from a single emission source. PLUVUE II uses Gaussian 
formulations to predict transport and dispersion. The model includes 
chemical reactions, optical effects and surface deposition. Four types 
of optics calculations are made: horizontal and non-horizontal views 
through the plume with a sky viewing background; horizontal views 
through the plume with white, gray and black viewing backgrounds; and 
horizontal views along the axis of the plume with a sky viewing 
background.

                  a. Recommendations for Regulatory Use

    The Plume Visibility Model (PLUVUE II) may be used on a case-by-case 
basis as a third level screening model. When applying PLUVUE II, the 
following precautions should be taken:
    1. Treat the optical effects of NO2 and particles 
separately as well as together to avoid cancellation of NO2 
absorption with particle scattering.
    2. Examine the visual impact of the plume in 0.1 (or 0), 0.5, and 
1.0 times the expected level of particulate matter in the background 
air.
    3. Examine the visual impact of the plume over the full range of 
observer-plume sun angles.

[[Page 467]]

    4. The user should consult the appropriate Federal Land Manager when 
using PLUVUE II to assess visibility impacts in a Class I area.

                          b. Input Requirements

    Source data requirements are: location and elevation; emission rates 
of SO2, NOX, and particulates; flue gas flow rate, 
exit velocity, and exit temperature; flue gas oxygen content; properties 
(including density, mass median and standard geometric deviation of 
radius) of the emitted aerosols in the accumulation (0.1-1.0m) 
and coarse (1.0-10.m) size modes; and deposition velocities for 
SO2, NOX, coarse mode aerosol, and accumulations 
mode aerosol.
    Meteorological data requirements are: stability class, wind 
direction (for an observer-based run), wind speed, lapse rate, air 
temperature, relative humidity, and mixing height.
    Other data requirements are: ambient background concentrations of 
NOX, NO2, O3, and SO2, and 
background visual range of sulfate and nitrate concentrations.
    Receptor (observer) data requirements are: location, terrain 
elevation at points along plume trajectory, white, gray, and black 
viewing backgrounds, the distance from the observer to the terrain 
observed behind the plume.

                                c. Output

    Printed output includes plume concentrations and visual effects at 
specified downwind distances for calculated or specified lines of sight.

                            d. Type of Model

    PLUVUE II is a Gaussian plume model. Visibility impairment is 
quantified once the spectral light intensity has been calculated for the 
specific lines of sight. Visibility impairment includes visual range 
reduction, plume contrast, relative coloration of a plume to its viewing 
background, and plume perceptibility due to its contrast and color with 
respect to a viewing background.

                           e. Pollutant Types

    PLUVUE II treats NO, NO2, SO2, 
H2SO4, HNO3, O3, primary and 
secondary particles to calculate effects on visibility.

                     f. Source Receptor Relationship

    For performing the optics calculations at selected points along the 
plume trajectory, PLUVUE II has two modes: plume based and observer 
based calculations. The major difference is the orientation of the 
viewer to the source and the plume.

                            g. Plume Behavior

    Briggs (1969, 1971, 1972) final plume rise equations are used.

                           h. Horizontal Winds

    User-specified wind speed (and direction for an observer-based run) 
are assumed constant for the calculation.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    Constant, uniform (steady-state) wind is assumed for each hour. 
Straight line plume transport is assumed to all downwind distances.

                         k. Vertical Dispersion

    Rural dispersion coefficients from Turner (1969) are used, with no 
adjustment for surface roughness. Six stability classes are used.

                       l. Chemical Transformation

    The chemistry of NO, NO2, O3, OH, 
O(1D), SO2, HNO3, and 
H2SO4 is treated by means of nine reactions. 
Steady state approximations are used for radicals and for the NO/
NO2/O3 reactions.

                           m. Physical Removal

    Dry deposition of gaseous and particulate pollutants is treated 
using deposition velocities.

                          n. Evaluation Studies

    Bergstrom, R.W., C. Seigneur, B.L. Babson, H.Y. Holman and M.A. 
Wojcik, 1981. Comparison of the Observed and Predicted Visual Effects 
Caused by Power Plant Plumes. Atmospheric Environment, 15: 2135-2150.
    Bergstrom, R.W., Seigneur, C.D. Johnson and L.W. Richards, 1984. 
Measurements and Simulations of the Visual Effects of Particulate 
Plumes. Atmospheric Environment, 18(10): 2231-2244.
    Seigneur, C., R.W. Bergstrom and A.B. Hudischewskyj, 1982. 
Evaluation of the EPA PLUVUE Model and the ERT Visibility Model Based on 
the 1979 VISTTA Data Base. EPA Publication No. EPA-450/4-82-008. U.S. 
Environmental Protection Agency, Research Triangle Park, NC.
    White, W.H., C. Seigneur, D.W. Heinold, M.W. Eltgroth, L.W. 
Richards, P.T. Roberts, P.S. Bhardwaja, W.D. Conner and W.E. Wilson, Jr, 
1985. Predicting the Visibility of Chimney Plumes: An Inter-comparison 
of Four Models with Observations at a Well-Controlled Power Plant. 
Atmospheric Environment, 19: 515-528.

[[Page 468]]

            B.13 Point, Area, Line Source Algorithm (PAL-DS)

                                Reference

    Petersen, W.B, 1978. User's Guide for PAL--A Gaussian-Plume 
Algorithm for Point, Area, and Line Sources. EPA Publication No. EPA-
600/4-78-013. Office of Research and Development, Research Triangle 
Park, NC. (NTIS No. PB 281306)
    Rao, K.S. and H.F. Snodgrass, 1982. PAL-DS Model: The PAL Model 
Including Deposition and Sedimentation. EPA Publication No. EPA-600/8-
82-023. Office of Research and Development, Research Triangle Park, NC. 
(NTIS No. PB 83-117739)

                              Availability

    The computer code is available on diskette (as PB 90-500802) from 
the National Technical Information Service (see section B.0).

                                Abstract

    PAL-DS is an acronym for this point, area, and line source algorithm 
and is a method of estimating short-term dispersion using Gaussian-plume 
steady-state assumptions. The algorithm can be used for estimating 
concentrations of non-reactive pollutants at 99 receptors for averaging 
times of 1 to 24 hours, and for a limited number of point, area, and 
line sources (99 of each type). This algorithm is not intended for 
application to entire urban areas but is intended, rather, to assess the 
impact on air quality, on scales of tens to hundreds of meters, of 
portions of urban areas such as shopping centers, large parking areas, 
and airports. Level terrain is assumed. The Gaussian point source 
equation estimates concentrations from point sources after determining 
the effective height of emission and the upwind and crosswind distance 
of the source from the receptor. Numerical integration of the Gaussian 
point source equation is used to determine concentrations from the four 
types of line sources. Subroutines are included that estimate 
concentrations for multiple lane line and curved path sources, special 
line sources (line sources with endpoints at different heights above 
ground), and special curved path sources. Integration over the area 
source, which includes edge effects from the source region, is done by 
considering finite line sources perpendicular to the wind at intervals 
upwind from the receptor. The crosswind integration is done 
analytically; integration upwind is done numerically by successive 
approximations.
    The PAL-DS model utilizes Gaussian plume-type diffusion-deposition 
algorithms based on analytical solutions of a gradient-transfer model. 
The PAL-DS model can treat deposition of both gaseous and suspended 
particulate pollutants in the plume since gravitational settling and dry 
deposition of the particles are explicitly accounted for. The analytical 
diffusion-deposition expressions listed in this report in the limit when 
pollutant settling and deposition velocities are zero, they reduce to 
the usual Gaussian plume diffusion algorithms in the PAL model.

                  a. Recommendations for Regulatory Use

    PAL-DS can be used if it can be demonstrated to estimate 
concentrations equivalent to those provided by the preferred model for a 
given application. PAL-DS must be executed in the equivalent mode.
    PAL-DS can be used on a case-by-case basis in lieu of a preferred 
model if it can be demonstrated, using the criteria in section 3.2, that 
PAL-DS is more appropriate for the specific application. In this case 
the model options/modes which are most appropriate for the application 
should be used.

                          b. Input Requirements

    Source data: point-sources--emission rate, physical stack height, 
stack gas temperature, stack gas velocity, stack diameter, stack gas 
volume flow, coordinates of stack, initial y and 
z; area sources--source strength, size of area 
source, coordinates of S.W. corner, and height of area source; and line 
sources--source strength, number of lanes, height of source, coordinates 
of end points, initial y and z, 
width of line source, and width of median. Diurnal variations in 
emissions are permitted. When applicable, the settling velocity and 
deposition velocity are also permitted.
    Meteorological data: wind profile exponents, anemometer height, wind 
direction and speed, stability class, mixing height, air temperature, 
and hourly variations in emission rate.
    Receptor data: receptor coordinates.

                                c. Output

    Printed output includes:
    Hourly concentration and deposition flux for each source type at 
each receptor; and
    Average concentration for up to 24 hours for each source type at 
each receptor.

                            d. Type of Model

    PAL-DS is a Gaussian plume model.

                           e. Pollutant Types

    PAL-DS may be used to model non-reactive pollutants.

                    f. Source-Receptor Relationships

    Up to 99 sources of each of 6 source types: point, area, and 4 types 
of line sources.
    Source and receptor coordinates are uniquely defined.
    Unique stack height for each source.

[[Page 469]]

    Coordinates of receptor locations are user defined.

                            g. Plume Behavior

    Briggs final plume rise equations are used.
    Fumigation and downwash are not treated.
    If plume height exceeds mixing height, concentrations are assumed 
equal to zero.
    Surface concentrations are set to zero when the plume centerline 
exceeds mixing height.

                           h. Horizontal Winds

    User-supplied hourly wind data are used.
    Constant, uniform (steady-state) wind is assumed within each hour. 
Wind is assumed to increase with height.

                         i. Vertical Wind Speeds

    Assumed equal to zero.

                        j. Horizontal Dispersion

    Rural dispersion coefficients from Turner (1969) are used with no 
adjustments made for surface roughness.
    Six stability classes are used.
    Dispersion coefficients (Pasquill-Gifford) are assumed based on a 
3cm roughness height.

                         k. Vertical Dispersion

    Six stability classes are used.
    Rural dispersion coefficients from Turner (1969) are used; no 
further adjustments are made for variation in surface roughness, 
transport or averaging time.
    Multiple reflection is handled by summation of series until the 
vertical standard deviation equals 1.6 times mixing height. Uniform 
vertical mixing is assumed thereafter.

                       l. Chemical Transformation

    Not treated.

                           m. Physical Removal

    PAL-DS can treat deposition of both gaseous and suspended 
particulates in the plume since gravitational settling and dry 
deposition of the particles are explicitly accounted for.

                          n. Evaluation Studies

    None Cited.

                   B.14 Reactive Plume Model (RPM-IV)

                                Reference

    Environmental Protection Agency, 1993. Reactive Plume Model IV (RPM-
IV) User's Guide. EPA Publication No. EPA-454/B-93-012. U.S. 
Environmental Protection Agency (ESRL), Research Triangle Park, NC. 
(NTIS No. PB 93-217412)

                              Availability

    The above report and model computer code are available on the 
Support Center for Regulatory Air Models Bulletin Board System. The 
model code is also available on diskette (as PB 96-502026) from the 
National Technical Information Service (see section B.0).

                                Abstract

    The Reactive Plume Model, RPM-IV, is a computerized model used for 
estimating short-term concentrations of primary and secondary reactive 
pollutants resulting from single or, in some special cases, multiple 
sources if they are aligned with the mean wind direction. The model is 
capable of simulating the complex interaction of plume dispersion and 
non-linear photochemistry. If Carbon Mechanism IV (CBM-IV) is used, 
emissions must be disaggregated into carbon bond classes prior to model 
application. The model can be run on a mainframe computer, workstation, 
or IBM-compatible PC with at least 2 megabytes of memory. A major 
feature of RPM-IV is its ability to interface with input and output 
files from EPA's Regional Oxidant Model (ROM) and Urban Airshed Model 
(UAM) to provide an internally consistent set of modeled ambient 
concentrations for various pollutant species.

                  a. Recommendations for Regulatory Use

    There is no specific recommendation at the present time. RPM-IV may 
be used on a case-by-case basis.

                          b. Input Requirements

    Source data requirements are: emission rates, name, and molecular 
weight of each species of pollutant emitted; ambient pressure, ambient 
temperature, stack height, stack diameter, stack exit velocity, stack 
gas temperature, and location.
    Meteorological data requirements are: wind speeds, plume widths or 
stability classes, photolytic rate constants, and plume depths or 
stability classes.
    Receptor data requirements are: downwind distances or travel times 
at which calculations are to be made.
    Initial concentration of all species is required, and the 
specification of downwind ambient concentrations to be entrained by the 
plume is optional.

                                c. Output

    Short-term concentrations of primary and secondary pollutants at 
either user specified time increments, or user specified downwind 
distances.

                            d. Type of Model

    Reactive Gaussian plume model.

[[Page 470]]

                           e. Pollutant Types

    Currently, using the Carbon Bond Mechanism (CBM-IV), 34 species are 
simulated (82 reactions), including NO, NO2, O3, 
SO2, SO4, five categories of reactive 
hydrocarbons, secondary nitrogen compounds, organic aerosols, and 
radical species.

                    f. Source-Receptor Relationships

    Single point source.
    Single area or volume source.
    Multiple sources can be simulated if they are lined up along the 
wind trajectory.
    Predicted concentrations are obtained at a user specified time 
increment, or at user specified downwind distances.

                            g. Plume Behavior

    Briggs (1971) plume rise equations are used.

                           h. Horizontal Winds

    User specifies wind speeds as a function of time.

                         i. Vertical Wind Speed

    Not treated.

                        j. Horizontal Dispersion

    User specified plume widths, or user may specify stability and 
widths will be computed using Turner (1969).

                         k. Vertical Dispersion

    User specified plume depths, or user may specify stability in which 
case depths will be calculated using Turner (1969). Note that vertical 
uniformity in plume concentration is assumed.

                       l. Chemical Transformation

    RPM-IV has the flexibility of using any user input chemical kinetic 
mechanism. Currently it is run using the chemistry of the Carbon Bond 
Mechanism, CBM-IV (Gery et al., 1988). The CBM-IV mechanism, as 
incorporated in RPM-IV, utilizes an updated simulation of PAN chemistry 
that includes a peroxy-peroxy radical termination reaction, significant 
when the atmosphere is NOX-limited (Gery et al., 1989). As 
stated above, the current CBM-IV mechanism accommodates 34 species and 
82 reactions focusing primarily on hydrocarbon/nitrogen oxides and ozone 
photochemistry.

                           m. Physical Removal

    Not treated.

                          n. Evaluation Studies

    Stewart, D.A. and M-K Liu, 1981. Development and Application of a 
Reactive Plume Model. Atmospheric Environment, 15: 2377-2393.

                  B.15 Shoreline Dispersion Model (SDM)

                                Reference

    PEI Associates, 1988. User's Guide to SDM-A Shoreline Dispersion 
Model. EPA Publication No. EPA-450/4-88-017. U.S. Environmental 
Protection Agency, Research Triangle Park, NC. (NTIS No. PB 89-164305)

                              Availability

    The model code is available on the Support Center for Regulatory Air 
Models Bulletin Board System (see section B.0).

                                Abstract

    SDM is a hybrid multi-point Gaussian dispersion model that 
calculates source impact for those hours during the year when fumigation 
events are expected using a special fumigation algorithm and the MPTER 
regulatory model for the remaining hours (see appendix A).

                  a. Recommendations for Regulatory Use

    SDM may be used on a case-by-case basis for the following 
applications:
     Tall stationary point sources located at a shoreline of any 
large body of water;
     Rural or urban areas;
     Flat terrain;
     Transport distances less than 50 km;
     1-hour to 1-year averaging times.

                          b. Input Requirements

    Source data: location, emission rate, physical stack height, stack 
gas exit velocity, stack inside diameter, stack gas temperature and 
shoreline coordinates.
    Meteorological data: hourly values of mean wind speed within the 
Thermal Internal Boundary Layer (TIBL) and at stack height; mean 
potential temperature over land and over water; over water lapse rate; 
and surface sensible heat flux. In addition to these meteorological 
data, SDM access standard NWS surface and upper air meteorological data 
through the RAMMET preprocessor.
    Receptor data: coordinates for each receptor.

                                c. Output

    Printed output includes the MPTER model output as well as: special 
shoreline fumigation applicability report for each day and source; high-
five tables on the standard output with ``F'' designation next to the 
concentration if that averaging period includes a fumigation event.

                            d. Type of Model

    SDM is hybrid Gaussian model.

[[Page 471]]

                           e. Pollutant Types

    SDM may be used to model primary pollutants. Settling and deposition 
are not treated.

                    f. Source-Receptor Relationships

    SDM applies user-specified locations of stationary point sources and 
receptors. User input stack height, shoreline orientation and source 
characteristics for each source. No topographic elevation is input; flat 
terrain is assumed.

                            g. Plume Behavior

    SDM uses Briggs (1975) plume rise for final rise. SDM does not treat 
stack tip or building downwash.

                           h. Horizontal Winds

    Constant, uniform (steady-state) wind is assumed for an hour. 
Straight line plume transport is assumed to all downwind distances. 
Separate wind speed profile exponents (EPA, 1980) for both rural and 
urban cases are assumed.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Horizontal Dispersion

    For the fumigation algorithm coefficients based on Misra (1980) and 
Misra and McMillan (1980) are used for plume transport in stable air 
above TIBL and based on Lamb (1978) for transport in the unstable air 
below the TIBL. An effective horizontal dispersion coefficient based on 
Misra and Onlock (1982) is used. For nonfumigation periods, algorithms 
contained in the MPTER model are used (see appendix A).

                         k. Vertical Dispersion

    For the fumigation algorithm, coefficients based on Misra (1980) and 
Misra and McMillan (1980) are used.

                       l. Chemical Transformation

    Chemical transformation is not included in the fumigation algorithm.

                           m. Physical Removal

    Physical removal is not explicitly treated.

                          n. Evaluation Studies

    Environmental Protection Agency, 1987. Analysis and Evaluation of 
Statistical Coastal Fumigation Models. EPA Publication No. EPA-450/4-87-
002. U.S. Environmental Protection Agency, Research Triangle Park, NC. 
(NTIS PB 87-175519)

                               B.16 SHORTZ

                                Reference

    Bjorklund, J.R. and J.F. Bowers, 1982. User's Instructions for the 
SHORTZ and LONGZ Computer Programs, Volumes I and II. EPA Publication 
No. EPA-903/9-82-004a and b. U.S. Environmental Protection Agency, 
Region III, Philadelphia, PA.

                              Availability

    The computer code is available on the Support Center for Regulatory 
Air Models Bulletin Board System and on diskette (as PB 96-501986) from 
the National Technical Information Service (see section B.0).

                                Abstract

    SHORTZ utilizes the steady state bivariate Gaussian plume 
formulation for both urban and rural areas in flat or complex terrain to 
calculate ground-level ambient air concentrations. The model can 
calculate 1-hour, 2-hour, 3-hour etc. average concentrations due to 
emissions from stacks, buildings and area sources for up to 300 
arbitrarily placed sources. The output consists of total concentration 
at each receptor due to emissions from each user-specified source or 
group of sources, including all sources. If the option for gravitational 
settling is invoked, analysis cannot be accomplished in complex terrain 
without violating mass continuity.

                  a. Recommendations for Regulatory Use

    SHORTZ can be used if it can be demonstrated to estimate 
concentrations equivalent to those provided by the preferred model for a 
given application. SHORTZ must be executed in the equivalent mode.
    SHORTZ can be used on a case-by-case basis in lieu of a preferred 
model if it can be demonstrated, using the criteria in section 3.2, that 
SHORTZ is more appropriate for the specific application. In this case 
the model options/modes which are most appropriate for the application 
should be used.

                          b. Input Requirements

    Source data requirements are: for point, building or area sources, 
location, elevation, total emission rate (optionally classified by 
gravitational settling velocity) and decay coefficient; for stack 
sources, stack height, effluent temperature, effluent exit velocity, 
stack radius (inner), actual volumetric flow rate, and ground elevation 
(optional); for building sources, height, length and width, and 
orientation; for area sources, characteristic vertical dimension, and 
length, width and orientation.
    Meteorological data requirements are: wind speed and measurement 
height, wind profile exponents, wind direction, standard deviations of 
vertical and horizontal wind directions, (i.e., vertical and lateral 
turbulent

[[Page 472]]

intensities), mixing height, air temperature, and vertical potential 
temperature gradient.
    Receptor data requirements are: coordinates, ground elevation.

                                c. Output

    Printed output includes total concentration due to emissions from 
user-specified source groups, including the combined emissions from all 
sources (with optional allowance for depletion by deposition).

                            d. Type of Model

    SHORTZ is a Gaussian plume model.

                           e. Pollutant Types

    SHORTZ may be used to model primary pollutants. Settling and 
deposition of particulates are treated.

                    f. Source-Receptor Relationships

    User specified locations for sources and receptors are used.
    Receptors are assumed to be at ground level.

                            g. Plume Behavior

    Plume rise equations of Bjorklund and Bowers (1982) are used.
    Stack tip downwash (Bjorklund and Bowers, 1982) is included.
    All plumes move horizontally and will fully intercept elevated 
terrain.
    Plumes above mixing height are ignored.
    Perfect reflection at mixing height is assumed for plumes below the 
mixing height.
    Plume rise is limited when the mean wind at stack height approaches 
or exceeds stack exit velocity.
    Perfect reflection at ground is assumed for pollutants with no 
settling velocity.
    Zero reflection at ground is assumed for pollutants with finite 
settling velocity.
    Tilted plume is used for pollutants with settling velocity 
specified. Buoyancy-induced dispersion (Briggs, 1972) is included.

                           h. Horizontal Winds

    Winds are assumed homogeneous and steady-state.
    Wind speed profile exponents are functions of both stability class 
and wind speed. Default values are specified in Bjorklund and Bowers 
(1982).

                         i. Vertical Wind Speed

    Vertical winds are assumed equal to zero.

                        j. Horizontal Dispersion

    Horizontal plume size is derived from input lateral turbulent 
intensities using adjustments to plume height, and rate of plume growth 
with downwind distance specified in Bjorklund and Bowers (1982).

                         k. Vertical Dispersion

    Vertical plume size is derived from input vertical turbulent 
intensities using adjustments to plume height and rate of plume growth 
with downwind distance specified in Bjorklund and Bowers (1982).

                       l. Chemical Transformation

    Chemical transformations are treated using exponential decay. Time 
constant is input by the user.

                           m. Physical Removal

    Settling and deposition of particulates are treated.

                          n. Evaluation Studies

    Bjorklund, J.R. and J.F. Bowers, 1982. User's Instructions for the 
SHORTZ and LONGZ Computer Programs. EPA Publication No. EPA-903/9-82-
004. EPA Environmental Protection Agency, Region III, Philadelphia, PA.
    Wackter, D. and R. Londergan, 1984. Evaluation of Complex Terrain 
Air Quality Simulation Models. EPA Publication No. EPA-450/4-84-017. 
U.S. Environmental Protection Agency, Research Triangle Park, NC.

                      B.17 Simple Line-Source Model

                                Reference

    Chock, D.P., 1980. User's Guide for the Simple Line-Source Model for 
Vehicle Exhaust Dispersion Near a Road. Ford Research Laboratory, 
Dearborn, MI.

                              Availability

    Copies of the above reference are available without charge from: Dr. 
D.P. Chock, Ford Research Laboratory, P.O. Box 2053; MD-3083, Dearborn, 
MI 48121-2053. The short model algorithm is contained in the User's 
Guide.

                                Abstract

    The Simple Line-Source Model is a simple steady-state Gaussian plume 
model which can be used to determine hourly (or half-hourly) averages of 
exhaust concentrations within 100m from a roadway on a relatively flat 
terrain. The model allows for plume rise due to the heated exhaust, 
which can be important when the crossroad wind is very low. The model 
also utilizes a new set of vertical dispersion parameters which reflects 
the influence of traffic-induced turbulence.

                  a. Recommendations for Regulatory Use

    The Simple Line-Source Model can be used if it can be demonstrated 
to estimate concentrations equivalent to those provided by the preferred 
model for a given application. The model must be executed in the 
equivalent mode.

[[Page 473]]

    The Simple Line-Source Model can be used on a case-by-case basis in 
lieu of a preferred model if it can be demonstrated, using criteria in 
section 3.2, that it is more appropriate for the specific application. 
In this case the model options/modes which are most appropriate for the 
application should be used.

                          b. Input Requirements

    Source data requirements are: emission rate per unit length per 
lane, the number of lanes on each road, distances from lane centers to 
the receptor, source and receptor heights.
    Meteorological data requirements are: buoyancy flux, ambient 
stability condition, ambient wind and its direction relative to the 
road.
    Receptor data requirements are: distance and height above ground.

                                c. Output

    Printed output includes hourly or (half-hourly) concentrations at 
the receptor due to exhaust emission from a road (or a system of roads 
by summing the results from repeated model applications).

                            d. Type of Model

    The Simple Line-Source Model is a Gaussian plume model.

                           e. Pollutant Types

    The Simple Line-Source Model can be used to model primary 
pollutants. Settling and deposition are not treated.

                     f. Source-Receptor Relationship

    The Simple Line-Source Model treats arbitrary location of line 
sources and receptors.

                            g. Plume Behavior

    Plume-rise formula adequate for a heated line source is used.

                           h. Horizontal Winds

    The Simple Line-Source Model uses user-supplied hourly (or half-
hourly) ambient wind speed and direction. The wind measurements are from 
a height of 5 to 10m.

                         i. Vertical Wind Speed

    Vertical wind speed is assumed equal to zero.

                        j. Dispersion Parameters

    Horizontal dispersion parameter is not used.

                         k. Vertical Dispersion

    A vertical dispersion parameter is used which is a function of 
stability and wind-road angle. Three stability classes are used: 
unstable, neutral and stable. The parameters take into account the 
effect of traffic-generated turbulence (Chock, 1980).

                       l. Chemical Transformation

    Not treated.

                           m. Physical Removal

    Not treated.

                          n. Evaluation Studies

    Chock, D.P., 1978. A Simple Line-Source Model for Dispersion Near 
Roadways. Atmospheric Environment, 12: 823-829.
    Sistla, G., P. Samson, M. Keenan and S.T. Rao, 1979. A Study of 
Pollutant Dispersion Near Highways. Atmospheric Environment, 13: 669-
685.

                                B.18 SLAB

                               Reference:

    Ermak, D.L., 1990. User's Manual for SLAB: An Atmospheric Dispersion 
Model for Denser-than-Air Releases (UCRL-MA-105607), Lawrence Livermore 
National Laboratory.

                              Availability

    The computer code can be obtained from: Energy Science and 
Technology Center, P.O. Box 1020, Oak Ridge, TN 37830, Phone (615) 576-
2606.
    The User's Manual (as DE 91-008443) can be obtained from the 
National Technical Information Service. The computer code is also 
available on the Support Center for Regulatory Air Models Bulletin Board 
System (Public Upload/ Download Area; see section B.0.)

                                Abstract

    The SLAB model is a computer model, PC-based, that simulates the 
atmospheric dispersion of denser-than-air releases. The types of 
releases treated by the model include a ground-level evaporating pool, 
an elevated horizontal jet, a stack or elevated vertical jet and an 
instantaneous volume source. All sources except the evaporating pool may 
be characterized as aerosols. Only one type of release can be processed 
in any individual simulation. Also, the model simulates only one set of 
meteorological conditions; therefore direct application of the model 
over time periods longer than one or two hours is not recommended.

                       a. Recommendations for use

    The SLAB model should be used as a refined model to estimate spatial 
and temporal distribution of short-term ambient concentration (e.g., 1-
hour or less averaging times) and the expected area of exposure to

[[Page 474]]

concentrations above specified threshold values for toxic chemical 
releases where the release is suspected to be denser than the ambient 
air.

                          b. Input Requirements

    The SLAB model is executed in the batch mode. Data are input 
directly from an external input file. There are 29 input parameters 
required to run each simulation. These parameters are divided into 5 
categories by the user's guide: source type, source properties, spill 
properties, field properties, and meteorological parameters. The model 
is not designed to accept real-time meteorological data or convert units 
of input values. Chemical property data are not available within the 
model and must be input by the user. Some chemical and physical property 
data are available in the user's guide.
    Source type is chosen as one of the following: evaporating pool 
release, horizontal jet release, vertical jet or stack release, or 
instantaneous or short duration evaporating pool release.
    Source property data requirements are physical and chemical 
properties (molecular weight, vapor heat capacity at constant pressure; 
boiling point; latent heat of vaporization; liquid heat capacity; liquid 
density; saturation pressure constants), and initial liquid mass 
fraction in the release.
    Spill properties include: source temperature, emission rate, source 
dimensions, instantaneous source mass, release duration, and elevation 
above ground level.
    Required field properties are: desired concentration averaging time, 
maximum downwind distance (to stop the calculation), and four separate 
heights at which the concentration calculations are to be made.
    Meteorological parameter requirements are: ambient measurement 
height, ambient wind speed at designated ambient measurement height, 
ambient temperature, surface roughness, relative humidity, atmospheric 
stability class, and inverse Monin-Obukhov length (optional, only used 
as an input parameter when stability class is unknown).

                                c. Output

    No graphical output is generated by the current version of this 
program. The output print file is automatically saved and must be sent 
to the appropriate printer by the user after program execution. Printed 
output includes in tabular form:
    Listing of model input data;
    Instantaneous spatially-averaged cloud parameters--time, downwind 
distance, magnitude of peak concentration, cloud dimensions (including 
length for puff-type simulations), volume (or mole) and mass fractions, 
downwind velocity, vapor mass fraction, density, temperature, cloud 
velocity, vapor fraction, water content, gravity flow velocities, and 
entrainment velocities;
    Time-averaged cloud parameters--parameters which may be used 
externally to calculate time-averaged concentrations at any location 
within the simulation domain (tabulated as functions of downwind 
distance);
    Time-averaged concentration values at plume centerline and at five 
off-centerline distances (off-centerline distances are multiples of the 
effective cloud half-width, which varies as a function of downwind 
distance) at four user-specified heights and at the height of the plume 
centerline.

                            d. Type of Model

    As described by Ermak (1989), transport and dispersion are 
calculated by solving the conservation equations for mass, species, 
energy, and momentum, with the cloud being modeled as either a steady-
state plume, a transient puff, or a combination of both, depending on 
the duration of the release. In the steady-state plume mode, the 
crosswind-averaged conservation equations are solved and all variables 
depend only on the downwind distance. In the transient puff mode, the 
volume-averaged conservation equations are solved, and all variables 
depend only on the downwind travel time of the puff center of mass. Time 
is related to downwind distance by the height-averaged ambient wind 
speed. The basic conservation equations are solved via a numerical 
integration scheme in space and time.

                           e. Pollutant Types

    Pollutants are assumed to be non-reactive and non-depositing dense 
gases or liquid-vapor mixtures (aerosols). Surface heat transfer and 
water vapor flux are also included in the model.

                    f. Source-Receptor Relationships

    Only one source can be modeled at a time.
    There is no limitation to the number of receptors; the downwind 
receptor distances are internally-calculated by the model. The SLAB 
calculation is carried out up to the user-specified maximum downwind 
distance.
    The model contains submodels for the source characterization of 
evaporating pools, elevated vertical or horizontal jets, and 
instantaneous volume sources.

                            g. Plume Behavior

    Plume trajectory and dispersion is based on crosswind-averaged mass, 
species, energy, and momentum balance equations. Surrounding terrain is 
assumed to be flat and of uniform surface roughness. No obstacle or 
building effects are taken into account.

[[Page 475]]

                           h. Horizontal Winds

    A power law approximation of the logarithmic velocity profile which 
accounts for stability and surface roughness is used.

                         i. Vertical Wind Speed

    Not treated.

                         j. Vertical Dispersion

    The crosswind dispersion parameters are calculated from formulas 
reported by Morgan et al. (1983), which are based on experimental data 
from several sources. The formulas account for entrainment due to 
atmospheric turbulence, surface friction, thermal convection due to 
ground heating, differential motion between the air and the cloud, and 
damping due to stable density stratification within the cloud.

                        k. Horizontal Dispersion

    The horizontal dispersion parameters are calculated from formulas 
similar to those described for vertical dispersion, also from the work 
of Morgan et al. (1983).

                       l. Chemical Transformation

    The thermodynamics of the mixing of the dense gas or aerosol with 
ambient air (including water vapor) are treated. The relationship 
between the vapor and liquid fractions within the cloud is treated using 
the local thermodynamic equilibrium approximation. Reactions of released 
chemicals with water or ambient air are not treated.

                           m. Physical Removal

    Not treated.

                          n. Evaluation Studies

    Blewitt, D.N., J.F. Yohn and D.L. Ermak, 1987. An Evaluation of SLAB 
and DEGADIS Heavy Gas Dispersion Models Using the HF Spill Test Data. 
Proceedings, AIChE International Conference on Vapor Cloud Modeling, 
Boston, MA, November, pp. 56-80.
    Ermak, D.L., S.T. Chan, D.L. Morgan and L.K. Morris, 1982. A 
Comparison of Dense Gas Dispersion Model Simulations with Burro Series 
LNG Spill Test Results. J. Haz. Matls., 6: 129-160.
    Zapert, J.G., R.J. Londergan and H. Thistle, 1991. Evaluation of 
Dense Gas Simulation Models. EPA Publication No. EPA-450/4-90-018. U.S. 
Environmental Protection Agency, Research Triangle Park, NC.

                          B.19 WYNDvalley Model

                                Reference

    Harrison, Halstead, 1992. ``A User's Guide to WYNDvalley 3.11, an 
Eulerian-Grid Air-Quality Dispersion Model with Versatile Boundaries, 
Sources, and Winds,'' WYNDsoft Inc., Mercer Island, WA.

                              Availability

    Copies of the user's guide and the executable model computer codes 
are available at a cost of $295.00 from: WYNDsoft, Incorporated, 6333 
77th Avenue, Mercer Island, WA 98040, Phone: (206) 232-1819.

                                Abstract

    WYNDvalley 3.11 is a multi-layer (up to five vertical layers) 
Eulerian grid dispersion model that permits users flexibility in 
defining borders around the areas to be modeled, the boundary conditions 
at these borders, the intensities and locations of emissions sources, 
and the winds and diffusivities that affect the dispersion of 
atmospheric pollutants. The model's output includes gridded contour 
plots of pollutant concentrations for the highest brief episodes (during 
any single time step), the highest and second-highest 24-hour averages, 
averaged dry and wet deposition fluxes, and a colored ``movie'' showing 
evolving dispersal of pollutant concentrations, together with temporal 
plots of the concentrations at specified receptor sites and statistical 
inference of the probabilities that standards will be exceeded at those 
sites. WYNDvalley is implemented on IBM compatible microcomputers, with 
interactive data input and color graphics display.

                  a. Recommendations for Regulatory Use

    WYNDvalley may be used on a case-by-case basis to estimate 
concentrations during valley stagnation periods of 24 hours or longer. 
Recommended inputs are listed below.

------------------------------------------------------------------------
                 Variable                         Recommended value
------------------------------------------------------------------------
Horizontal cell dimension.................  250 to 500 meters.
Vertical layers...........................  3 to 5.
Layer depth...............................  50 to 100 meters.
Background (internal to model)............  Zero (background should be
                                             added externally to model
                                             estimates).
Lateral meander velocity..................  Default.
Diffusivities.............................  Default.
Ventilation parameter (upper boundary       Default.
 condition).
Dry deposition velocity...................  Zero (site-specific).
Washout ratio.............................  Zero (site-specific).
------------------------------------------------------------------------

                          b. Input Requirements

    Input data, including model options, modeling domain boundaries, 
boundary conditions, receptor locations, source locations, and emission 
rates, may be entered interactively, or through existing template files 
from a previous run. Meteorological data, including wind speeds, wind 
directions, rain rates (optionally, for wet deposition calculations), 
and time of day and year, may be of arbitrary time increment (usually an 
hour) and are entered into the model through an external meteorological 
data file. Optionally, users may specify diffusivities and

[[Page 476]]

upper boundary conditions for each time increment. Source emission rates 
may be constant or modulated on a daily, weekly, and/or seasonal basis.

                                c. Output

    Output from WYNDvalley includes gridded contour maps of the highest 
pollutant concentrations at each time step and the highest and second-
highest 24-hour average concentrations. Output also includes the 
deposition patterns for wet, dry, and total fluxes of the pollutants to 
the surface, integrated over the simulation period. A running ``movie'' 
of the concentration patterns is displayed on the screen (with optional 
printout) as they evolve during the simulation. Output files include 
tables of daily-averaged pollutant concentrations at every modeled grid 
cell, and of hourly concentrations at up to eight specified receptors. 
Statistical analyses are performed on the hourly and daily data to 
estimate the probabilities that specified levels will be exceeded more 
than once during an arbitrary number of days with similar weather.

                            d. Type of Model

    WYNDvalley is a three dimensional Eulerian grid model.

                           e. Pollutant Types

    WYNDvalley may be used to model any inert pollutant.

                    f. Source-Receptor Relationships

    Source and receptors may be located anywhere within the user-defined 
modeling domain. All point and area sources, or portions of an area 
source, within a given grid cell are summed to define a representative 
emission rate for that cell. Concentrations are calculated for each and 
every grid cell in the modeling domain. Up to eight grid cells may be 
selected as receptors, for which time histories of concentration and 
deposition fluxes are determined, and probabilities of exceedance are 
calculated.

                            g. Plume Behavior

    Emissions for buoyant point sources are placed by the user in a grid 
cell which best reflects the expected effective plume height during 
stagnation conditions. Five vertical layers are available to the user.

                           h. Horizontal Winds

    During each time step in the model, the winds are assumed to be 
uniform throughout the modeling domain. Numerical diffusion is minimized 
in the advection algorithm. To account for terrain effects on winds and 
dispersion, an ad hoc algorithm is employed in the model to distribute 
concentrations near boundaries.

                         i. Vertical Wind Speed

    Winds are assumed to be constant with height.

                        j. Horizontal Dispersion

    Horizontal eddy diffusion coefficients may be entered explicitly by 
the user at every time step. Alternatively, a default algorithm may be 
invoked to estimate these coefficients from the wind velocities and 
their variances.

                         k. Vertical Dispersion

    Vertical eddy diffusion coefficients and a top-of-model boundary 
condition may be entered explicitly by the user at every time step. 
Alternatively, a default algorithm may be invoked to estimate these 
coefficients from the horizontal wind velocities and their variances, 
and from an empirical time-of-day correction derived from temperature 
gradient measurements and Monin-Obukhov similarities.

                       l. Chemical Transformation

    Chemical transformation is not explicitly treated by WYNDvalley.

                           m. Physical Removal

    WYNDvalley optionally simulates both wet and dry deposition. Dry 
deposition is proportional to concentration in the lowest layer, while 
wet deposition is proportional to rain rate and concentration in each 
layer. Appropriate coefficients (deposition velocities and washout 
ratios) are input by the user.

                          n. Evaluation Studies

    Harrison, H., G. Pade, C. Bowman and R. Wilson, 1990. Air Quality 
During Stagnations: A Comparison of RAM and WYNDvalley with PM-10 
Measurements at Five Sites. Journal of the Air & Waste Management 
Association, 40: 47-52.
    Maykut, N. et al., 1990. Evaluation of the Atmospheric Deposition of 
Toxic Contaminants to Puget Sound. State of Washington, Puget Sound 
Water Quality Authority, Seattle, WA.
    Yoshida, C., 1990. A Comparison of WYNDvalley Versions 2.12 and 3.0 
with PM-10 Measurements in Six Cities in the Pacific Northwest. Lane 
Regional Air Pollution Authority, Springfield, OR.

                            B. REF References

    Beals, G.A., 1971. A Guide to Local Dispersion of Air Pollutants. 
Air Weather Service Technical Report 214 (April 1971).
    Bjorklund, J.R. and J.F. Bowers, 1982. User's Instructions for the 
SHORTZ and LONGZ Computer Programs. EPA Publication No. EPA-903/9-82-
004a and b. U.S. Environmental Protection Agency, Region III, 
Philadelphia, PA.

[[Page 477]]

    Briggs, G.A., 1969. Plume Rise. U.S. Atomic Energy Commission 
Critical Review Series, Oak Ridge National Laboratory, Oak Ridge, TN. 
(NTIS No. TID-25075)
    Briggs, G.A., 1971. Some Recent Analyses of Plume Rise Observations. 
Proceedings of the Second International Clean Air Congress, edited by 
H.M. Englund and W.T. Berry. Academic Press, New York, NY.
    Briggs, G.A., 1972. Discussion on Chimney Plumes in Neutral and 
Stable Surroundings. Atmospheric Environment, 6: 507-510.
    Briggs, G.A., 1974. Diffusion Estimation for Small Emissions. USAEC 
Report ATDL-106. U.S. Atomic Energy Commission, Oak Ridge, TN.
    Briggs, G.A., 1975. Plume Rise Predictions. Lectures on Air 
Pollution and Environmental Impact Analyses. American Meteorological 
Society, Boston, MA, pp. 59-111.
    Briggs, G.A., 1984. Plume Rise and Buoyancy Effects. Atmospheric 
Science and Power Production, Darryl Randerson (Ed.). DOE Report DOE/
TIC-27601, Technical Information Center, Oak Ridge, TN. (NTIS No. 
DE84005177)
    Carpenter, S.B., T.L. Montgomery, J.M. Leavitt, W.C. Colbaugh and 
F.W. Thomas, 1971. Principal Plume Dispersion Models: TVA Power Plants. 
Journal of Air Pollution Control Association, 21: 491-495.
    Chock, D.P., 1980. User's Guide for the Simple Line-Source Model for 
Vehicle Exhaust Dispersion Near a Road. Environmental Science 
Department, General Motors Research Laboratories, Warren, MI.
    Colenbrander, G.W., 1980. A Mathematical Model for the Transient 
Behavior of Dense Vapor Clouds, 3rd International Symposium on Loss 
Prevention and Safety Promotion in the Process Industries, Basel, 
Switzerland.
    DeMarrais, G.A., 1959. Wind Speed Profiles at Brookhaven National 
Laboratory. Journal of Applied Meteorology, 16: 181-189.
    Ermak, D.L., 1989. A Description of the SLAB Model, presented at 
JANNAF Safety and Environmental Protection Subcommittee Meeting, San 
Antonio, TX, April, 1989.
    Gery, M.W., G.Z. Whitten and J.P. Killus, 1988. Development and 
Testing of CBM-IV for Urban and Regional Modeling. EPA Publication No. 
EPA-600/3-88-012. U.S. Environmental Protection Agency, Research 
Triangle Park, NC. (NTIS No. PB 88-180039)
    Gery, M.W., G.Z. Whitten, J.P. Killus and M.C. Dodge, 1989. A 
Photochemical Kinetics Mechanism for Urban and Regional Scale Computer 
Modeling. Journal of Geophysical Research, 94: 12,925-12,956.
    Gifford, F.A. and S.R. Hanna, 1970. Urban Air Pollution Modeling. 
Proceedings of the Second International Clean Air Congress, Academic 
Press, Washington, D.C.; pp. 140-1151.
    Gifford, F.A., 1975. Atmospheric Dispersion Models for Environmental 
Pollution Applications. Lectures on Air Pollution and Environmental 
Impact Analyses. American Meteorological Society, Boston, MA.
    Green, A.E., Singhal R.P. and R. Venkateswar, 1980. Analytical 
Extensions of the Gaussian Plume Model. Journal of the Air Pollution 
Control Association, 30: 773-776.
    Heffter, J.L., 1965. The Variations of Horizontal Diffusion 
Parameters with Time for Travel Periods of One Hour or Longer. Journal 
of Applied Meteorology, 4: 153-156.
    Heffter, J.L., 1980. Air Resources Laboratories Atmospheric 
Transport and Dispersion Model (ARL-ATAD). NOAA Technical Memorandum ERL 
ARL-81. Air Resources Laboratories, Silver Spring, MD.
    Irwin, J.S., 1979a. Estimating Plume Dispersion--A Recommended 
Generalized Scheme. Fourth Symposium on Turbulence, Diffusion and Air 
Pollution, Reno, Nevada.
    Irwin, J.S., 1979b. A Theoretical Variation of the Wind Profile 
Power-Law Exponent as a Function of Surface Roughness and Stability. 
Atmospheric Environment, 13: 191-194.
    MacCready, P.B., Baboolal, L.B. and P.B. Lissaman, 1974. Diffusion 
and Turbulence Aloft Over Complex Terrain. Preprint Volume, AMS 
Symposium on Atmospheric Diffusion and Air Pollution, Santa Barbara, CA. 
American Meteorological Society, Boston, MA.
    Moore, G.E., T.E. Stoeckenius and D.A. Stewart, 1982. A Survey of 
Statistical Measures of Model Performance and Accuracy for Several Air 
Quality Models. EPA Publication No. EPA-450/4-83-001. U.S. Environmental 
Protection Agency, Research Triangle Park, NC.
    Morgan, D.L., Jr., L.K. Morris and D.L. Ermak, 1983. SLAB: A Time-
Dependent Computer Model for the Dispersion of Heavy Gas Released in the 
Atmosphere, UCRL-53383, Lawrence Livermore National Laboratory, 
Livermore, CA.
    Pasquill, F., 1976. Atmospheric Dispersion Parameters in Gaussian 
Plume Modeling, Part II. EPA Publication No. EPA-600/4-76-030b. U.S. 
Environmental Protection Agency, Research Triangle Park, NC.
    Slade, D.H., 1968. Meteorology and Atomic Energy, U.S. Atomic Energy 
Commission, 445 pp. (NTIS No. TID-24190)
    Turner, D.B., 1964. A Diffusion Model of An Urban Area. Journal of 
Applied Meteorology, 3: 83-91.
    Turner, D.B., 1969. Workbook of Atmospheric Dispersion Estimates. 
PHS Publication No. 999-AP-26. U.S. Environmental Protection Agency, 
Research Triangle Park, NC.
    Van Dop, H., 1992. Buoyant Plume Rise in a Lagrangian Frame Work. 
Atmospheric Environment, 26A: 1335-1346.

[[Page 478]]

   Appendix C to Appendix W of Part 51--Example Air Quality Analysis 
                                Checklist

                            C.0 Introduction

    This checklist recommends a standardized set of data and a standard 
basic level of analysis needed for PSD applications and SIP revisions. 
The checklist implies a level of detail required to assess both PSD 
increments and the NAAQS. Individual cases may require more or less 
information and the Regional Meteorologist should be consulted at an 
early stage in the development of a data base for a modeling analysis.
    At pre-application meetings between source owner and reviewing 
authority, this checklist should prove useful in developing a consensus 
on the data base, modeling techniques and overall technical approach 
prior to the actual analyses. Such agreement will help avoid 
misunderstandings concerning the final results and may reduce the later 
need for additional analyses.

           EXAMPLE AIR QUALITY ANALYSIS CHECKLIST 1

    1. Source location map(s) showing location with respect to:
---------------------------------------------------------------------------

    \1\ The ``Screening Procedures for Estimating the Air Quality Impact 
of Stationary Sources, Revised'', October 1992 (EPA-450/R-92-019), 
should be used as a screening tool to determine whether modeling 
analyses are required. Screening procedures should be refined by the 
user to be site/problem specific.
---------------------------------------------------------------------------

     Urban areas 2
---------------------------------------------------------------------------

    \2\ Within 50km or distance to which source has a significant 
impact, whichever is less.
---------------------------------------------------------------------------

     PSD Class I areas
     Nonattainment areas \2\
     Topographic features (terrain, lakes, river valleys, etc.) 
\2\
     Other major existing sources \2\
     Other major sources subject to PSD requirements
     NWS meteorological observations (surface and upper air)
     On-site/local meteorological observations (surface and 
upper air)
     State/local/on-site air quality monitoring locations \2\
     Plant layout on a topographic map covering a 1km radius of 
the source with information sufficient to determine GEP stack heights
    2. Information on urban/rural characteristics:
     Land use within 3km of source classified according to Auer 
(1978): Correlation of land use and cover with meteorological anomalies. 
Journal of Applied Meteorology, 17: 636-643.
     Population
    -> total
    -> density
     Based on current guidance determination of whether the area 
should be addressed using urban or rural modeling methodology
    3. Emission inventory and operating/design parameters for major 
sources within region of significant impact of proposed site (same as 
required for applicant)
     Actual and allowable annual emission rates (g/s) and 
operating rates 3
---------------------------------------------------------------------------

    \3\ Particulate emissions should be specified as a function of 
particulate diameter and density ranges.
---------------------------------------------------------------------------

     Maximum design load short-term emission rate (g/s) \3\
     Associated emissions/stack characteristics as a function of 
load for maximum, average, and nominal operating conditions if stack 
height is less than GEP or located in complex terrain. Screening 
analyses as footnoted above or detailed analyses, if necessary, must be 
employed to determine the constraining load condition (e.g., 50%, 75%, 
or 100% load) to be relied upon in the short-term modeling analysis.
    --location (UTM's)
    --height of stack (m) and grade level above MSL
    --stack exit diameter (m)
    --exit velocity (m/s)
    --exit temperature ( deg.K)
     Area source emissions (rates, size of area, height of area 
source)\3\
     Location and dimensions of buildings (plant layout drawing)
    --to determine GEP stack height
    --to determine potential building downwash considerations for stack 
heights less than GEP
      Associated parameters
    --boiler size (megawatts, pounds/hr. steam, fuel consumption, etc.)
    --boiler parameters (% excess air, boiler type, type of firing, 
etc.)
    --operating conditions (pollutant content in fuel, hours of 
operation, capacity factor, % load for winter, summer, etc.)
    --pollutant control equipment parameters (design efficiency, 
operation record, e.g., can it be bypassed?, etc.)
     Anticipated growth changes
    4. Air quality monitoring data:
     Summary of existing observations for latest five years 
(including any additional quality assured measured data which can be 
obtained from any State or local agency or company) 4
---------------------------------------------------------------------------

    \4\ See footnote 2 of this appendix C.
---------------------------------------------------------------------------

     Comparison with standards
     Discussion of background due to uninventoried sources and 
contributions from outside the inventoried area and description of the 
method used for determination of background (should be consistent with 
the Guideline)

[[Page 479]]

    5. Meteorological data:
     Five consecutive years of the most recent representative 
sequential hourly National Weather Service (NWS) data, or one or more 
years of hourly sequential on-site data
     Discussion of meteorological conditions observed (as 
applied or modified for the site-specific area, i.e., identify possible 
variations due to difference between the monitoring site and the 
specific site of the source)
     Discussion of topographic/land use influences
    6. Air quality modeling analyses:
     Model each individual year for which data are available 
with a recommended model or model demonstrated to be acceptable on a 
case-by-case basis
    --urban dispersion coefficients for urban areas
    --rural dispersion coefficients for rural areas
     Evaluate downwash if stack height is less than GEP
     Define worst case meteorology
     Determine background and document method
    --long-term
    --short-term
     Provide topographic map(s) of receptor network with respect 
to location of all sources
     Follow current guidance on selection of receptor sites for 
refined analyses
     Include receptor terrain heights (if applicable) used in 
analyses
     Compare model estimates with measurements considering the 
upper ends of the frequency distribution
     Determine extent of significant impact; provide maps
     Define areas of maximum and highest, second-highest impacts 
due to applicant source (refer to format suggested in Air Quality 
Summary Tables)
    -> long-term
    -> short-term
    7. Comparison with acceptable air quality levels:
     NAAQS
     PSD increments
     Emission offset impacts if nonattainment
    8. Documentation and guidelines for modeling methodology:
     Follow guidance documents
    -> appendix W to 40 CFR part 51
    -> ``Screening Procedures for Estimating the Air Quality Impact of 
Stationary Sources, Revised'' (EPA-450/R-92-019), 1992
    -> ``Guideline for Determination of Good Engineering Practice Stack 
Height (Technical Support Document for the Stack Height Regulations)'' 
(EPA-450/4-80-023R), 1985
    -> ``Ambient Monitoring Guidelines for PSD'' (EPA-450/4-87-007), 
1987
    -> Applicable sections of 40 CFR parts 51 and 52.

                                    Air Quality Summary--For New Source Alone
          Pollutant:      __________________\1\       __________________\2\       __________________\2\
----------------------------------------------------------------------------------------------------------------
                                                      Highest  2d                    Highest  2d
                                        Highest          high           Highest          high          Annual
----------------------------------------------------------------------------------------------------------------
Concentration Due to Modeled        ..............  ..............  ..............  .............  .............
 Source (g/m3).
Background Concentration (g/m3).
Total Concentration (g/    ..............  ..............  ..............  .............  .............
 m3).
Receptor Distance (km) (or UTM      ..............  ..............  ..............  .............  .............
 easting).
Receptor Direction ( deg.) (or UTM  ..............  ..............  ..............  .............  .............
 northing).
Receptor Elevation (m)............  ..............  ..............  ..............  .............  .............
Wind Speed (m/s)..................  ..............  ..............  ..............  .............  .............
Wind Direction ( deg.)............  ..............  ..............  ..............  .............  .............
Mixing Depth (m)..................  ..............  ..............  ..............  .............  .............
Temperature ( deg.K)..............  ..............  ..............  ..............  .............  .............
Stability.........................  ..............  ..............  ..............  .............  .............
Day/Month/Year of Occurrence......  ..............  ..............  ..............  .............  .............
----------------------------------------------------------------------------------------------------------------
 
Surface Air Data From ____________________    Surface Station Elevation (m) ____________________
Anemometer Height Above Local Ground Level (m) ____________________
Upper Air Data From ________________________________________________
Period of Record Analyzed __________________________________________
Model Used ________________________________________________________
Recommended Model ______________________________________________
----------------------------------------------------------------------------------------------------------------
 1 Use separate sheet for each pollutant (SO2, PM-10, CO, NOX, HC, Pb, Hg, Asbestos, etc.).
2 List all appropriate averaging periods (1-hr, 3-hr, 8-hr, 24-hr, 30-day, 90-day, etc.) for which an air
  quality standard exists.


                                    Air Quality Summary--For All New Sources
          Pollutant:      __________________\1\       __________________\2\       __________________\2\
----------------------------------------------------------------------------------------------------------------
                                                      Highest 2nd                    Highest 2nd
                                        Highest          high           Highest          high          Annual
----------------------------------------------------------------------------------------------------------------
Concentration Due to Modeled        ..............  ..............  ..............  .............  .............
 Source (g/m3).

[[Page 480]]

 
Background Concentration (g/m3).
Total Concentration (g/    ..............  ..............  ..............  .............  .............
 m3).
Receptor Distance (km) (or UTM      ..............  ..............  ..............  .............  .............
 easting).
Receptor Direction ( deg.) (or UTM  ..............  ..............  ..............  .............  .............
 northing).
Receptor Elevation (m)............  ..............  ..............  ..............  .............  .............
Wind Speed (m/s)..................  ..............  ..............  ..............  .............  .............
Wind Direction ( deg.)............  ..............  ..............  ..............  .............  .............
Mixing Depth (m)..................  ..............  ..............  ..............  .............  .............
Temperature ( deg.K)..............  ..............  ..............  ..............  .............  .............
Stability.........................  ..............  ..............  ..............  .............  .............
Day/Month/Year of Occurrence......  ..............  ..............  ..............  .............  .............
----------------------------------------------------------------------------------------------------------------
 
Surface Air Data From ____________________    Surface Station Elevation (m) ____________________
Anemometer Height Above Local Ground Level (m) ____________________
Upper Air Data From ________________________________________________
Period of Record Analyzed __________________________________________
Model Used ________________________________________________________
Recommended Model ______________________________________________
----------------------------------------------------------------------------------------------------------------
1 Use separate sheet for each pollutant (SO2, PM-10, CO, NOX, HC, Pb, Hg, Asbestos, etc.).
2 List all appropriate averaging periods (l-hr, 3-hr, 8-hr, 24-hr, 30-day, 90-day, etc.) for which an air
  quality standard exists.


                                      Air Quality Summary--For All Sources
          Pollutant:      __________________\1\       __________________\2\       __________________\2\
----------------------------------------------------------------------------------------------------------------
                                                      Highest 2nd                    Highest 2nd
                                        Highest          high           Highest          high          Annual
----------------------------------------------------------------------------------------------------------------
Concentration Due to Modeled        ..............  ..............  ..............  .............  .............
 Source (g/m3).
Background Concentration (g/m3).
Total Concentration (g/    ..............  ..............  ..............  .............  .............
 m3).
Receptor Distance (km) (or UTM      ..............  ..............  ..............  .............  .............
 easting).
Receptor Direction ( deg.) (or UTM  ..............  ..............  ..............  .............  .............
 northing).
Receptor Elevation (m)............  ..............  ..............  ..............  .............  .............
Wind Speed (m/s)..................  ..............  ..............  ..............  .............  .............
Wind Direction ( deg.)............  ..............  ..............  ..............  .............  .............
Mixing Depth (m)..................  ..............  ..............  ..............  .............  .............
Temperature ( deg.K)..............  ..............  ..............  ..............  .............  .............
Stability.........................  ..............  ..............  ..............  .............  .............
Day/Month/Year of Occurrence......  ..............  ..............  ..............  .............  .............
----------------------------------------------------------------------------------------------------------------
 
Surface Air Data From ____________________    Surface Station Elevation (m) ____________________
Anemometer Height Above Local Ground Level (m) ____________________
Upper Air Data From ________________________________________________
Period of Record Analyzed __________________________________________
Model Used ________________________________________________________
Recommended Model ______________________________________________
----------------------------------------------------------------------------------------------------------------
\1\ Use separate sheet for each pollutant (SO2, PM-10, CO, NOX, HC, Pb, Hg, Asbestos, etc.)
\2\ List all appropriate averaging periods (1-hr, 3-hr, 8-hr, 24-hr, 30-day, 90-day, etc.) for which an air
  quality standard exists.


                                                                                                  Stack Parameters for Annual Modeling
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Emission rate                                                                                                                                       Building dimensions (m)
                                                   for each        Stack exit       Stack exit       Stack exit                                       GEP stack ht.      Stack base   --------------------------------------------------
          Stack No.               Serving       pollutant  (g/    diameter (m)   velocity  (m/s)   temperature (   Physical height     Stack (m)           (m)         elevation (m)
                                                      s)                                               deg.K)                                                                               Height           Width            Length
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 481]]


                                                                                               Stack Parameters for Short-Term Modeling 1
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Emission rate                                                                                                                                       Building dimensions (m)
                                                   for each        Stack exit       Stack exit       Stack exit                                        GEP stack ht.     Stack base   --------------------------------------------------
          Stack No.               Serving       pollutant  (g/    diameter (m)   velocity  (m/s)   temperature (   Physical height     Stack (m)           (m)         elevation (m)
                                                      s)                                               deg.K)                                                                               Height           Width            Length
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Separate tables for 50%, 75%, 100% of full operating condition (and any other operating conditions as determined by screening or detailed modeling analyses to represent constraining operating conditions) should be provided.


[61 FR 41840, Aug. 12, 1996]

     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 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

[[Page 482]]

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 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

[[Page 483]]

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).
    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):

[[Page 484]]

    (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;
    (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]


[[Page 485]]



                              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.

  Material Approved for Incorporation by Reference
  Table of CFR Titles and Chapters
  Alphabetical List of Agencies Appearing in the CFR
  List of CFR Sections Affected

[[Page 487]]

            Material Approved for Incorporation by Reference

                      (Revised as of July 1, 1999)

  The Director of the Federal Register has approved under 5 U.S.C. 
552(a) and 1 CFR Part 51 the incorporation by reference of the following 
publications. This list contains only those incorporations by reference 
effective as of the revision date of this volume. Incorporations by 
reference found within a regulation are effective upon the effective 
date of that regulation. For more information on incorporation by 
reference, see the preliminary pages of this volume.


40 CFR (PARTS 50 TO 51)

ENVIRONMENTAL PROTECTION AGENCY
                                                                  40 CFR


Environmental Protection Agency

  Office of Air Quality Planning and Standards, 
  Research Triangle Park, NC 27711
``Guidelines for Determining Best Available                    51.302(c)
  Retrofit Technology for Coal-Fired Power Plants 
  and Other Existing Stationary Facilities'', 
  (1980), EPA 450/3-80-009b.
``Guidelines on Air Quality Models (Revised)''                 51.166(l)
  (1986) and Supplement A (1987), EPA 450/2-78-
  027R.
  Copies may be obtained from: National Technical 
  Information Service, 5285 Port Royal Rd., 
  Springfield, VA 22161; Telephone: (703) 487-
  4650, FAX: (703) 487-4142



[[Page 489]]



                    Table of CFR Titles and Chapters




                      (Revised as of July 1, 1999)

                      Title 1--General Provisions

         I  Administrative Committee of the Federal Register 
                (Parts 1--49)
        II  Office of the Federal Register (Parts 50--299)
        IV  Miscellaneous Agencies (Parts 400--500)

                          Title 2--[Reserved]

                        Title 3--The President

         I  Executive Office of the President (Parts 100--199)

                           Title 4--Accounts

         I  General Accounting Office (Parts 1--99)
        II  Federal Claims Collection Standards (General 
                Accounting Office--Department of Justice) (Parts 
                100--299)

                   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  Advisory Committee on Federal Pay (Parts 1400--1499)
         V  The International Organizations Employees Loyalty 
                Board (Parts 1500--1599)
        VI  Federal Retirement Thrift Investment Board (Parts 
                1600--1699)
       VII  Advisory Commission on Intergovernmental Relations 
                (Parts 1700--1799)
      VIII  Office of Special Counsel (Parts 1800--1899)
        IX  Appalachian Regional Commission (Parts 1900--1999)
        XI  Armed Forces Retirement Home (Part 2100)
       XIV  Federal Labor Relations Authority, General Counsel of 
                the Federal Labor Relations Authority and Federal 
                Service Impasses Panel (Parts 2400--2499)
        XV  Office of Administration, Executive Office of the 
                President (Parts 2500--2599)
       XVI  Office of Government Ethics (Parts 2600--2699)
       XXI  Department of the Treasury (Parts 3100--3199)

[[Page 490]]

      XXII  Federal Deposit Insurance Corporation (Part 3201)
     XXIII  Department of Energy (Part 3301)
      XXIV  Federal Energy Regulatory Commission (Part 3401)
       XXV  Department of the Interior (Part 3501)
      XXVI  Department of Defense (Part 3601)
    XXVIII  Department of Justice (Part 3801)
      XXIX  Federal Communications Commission (Parts 3900--3999)
       XXX  Farm Credit System Insurance Corporation (Parts 4000--
                4099)
      XXXI  Farm Credit Administration (Parts 4100--4199)
    XXXIII  Overseas Private Investment Corporation (Part 4301)
      XXXV  Office of Personnel Management (Part 4501)
        XL  Interstate Commerce Commission (Part 5001)
       XLI  Commodity Futures Trading Commission (Part 5101)
      XLII  Department of Labor (Part 5201)
     XLIII  National Science Foundation (Part 5301)
       XLV  Department of Health and Human Services (Part 5501)
      XLVI  Postal Rate Commission (Part 5601)
     XLVII  Federal Trade Commission (Part 5701)
    XLVIII  Nuclear Regulatory Commission (Part 5801)
         L  Department of Transportation (Part 6001)
       LII  Export-Import Bank of the United States (Part 6201)
      LIII  Department of Education (Parts 6300--6399)
       LIV  Environmental Protection Agency (Part 6401)
      LVII  General Services Administration (Part 6701)
     LVIII  Board of Governors of the Federal Reserve System (Part 
                6801)
       LIX  National Aeronautics and Space Administration (Part 
                6901)
        LX  United States Postal Service (Part 7001)
       LXI  National Labor Relations Board (Part 7101)
      LXII  Equal Employment Opportunity Commission (Part 7201)
     LXIII  Inter-American Foundation (Part 7301)
       LXV  Department of Housing and Urban Development (Part 
                7501)
      LXVI  National Archives and Records Administration (Part 
                7601)
      LXIX  Tennessee Valley Authority (Part 7901)
      LXXI  Consumer Product Safety Commission (Part 8101)
     LXXIV  Federal Mine Safety and Health Review Commission (Part 
                8401)
     LXXVI  Federal Retirement Thrift Investment Board (Part 8601)
    LXXVII  Office of Management and Budget (Part 8701)

                          Title 6--[Reserved]

                         Title 7--Agriculture

            Subtitle A--Office of the Secretary of Agriculture 
                (Parts 0--26)
            Subtitle B--Regulations of the Department of 
                Agriculture

[[Page 491]]

         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  Grain Inspection, Packers and Stockyards 
                Administration (Federal Grain Inspection Service), 
                Department of Agriculture (Parts 800--899)
        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)
      XIII  Northeast Dairy Compact Commission (Parts 1300--1399)
       XIV  Commodity Credit Corporation, Department of 
                Agriculture (Parts 1400--1499)
        XV  Foreign Agricultural Service, Department of 
                Agriculture (Parts 1500--1599)
       XVI  Rural Telephone Bank, Department of Agriculture (Parts 
                1600--1699)
      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)
      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, 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)

[[Page 492]]

    XXXIII  Office of Transportation, Department of Agriculture 
                (Parts 3300--3399)
     XXXIV  Cooperative State Research, Education, and Extension 
                Service, Department of 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)

                    Title 8--Aliens and Nationality

         I  Immigration and Naturalization Service, Department of 
                Justice (Parts 1--499)

                 Title 9--Animals and Animal Products

         I  Animal and Plant Health Inspection Service, Department 
                of Agriculture (Parts 1--199)
        II  Grain Inspection, Packers and Stockyards 
                Administration (Packers and Stockyards Programs), 
                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)
      XVII  Defense Nuclear Facilities Safety Board (Parts 1700--
                1799)

                      Title 11--Federal Elections

         I  Federal Election Commission (Parts 1--9099)

                      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)

[[Page 493]]

        IV  Export-Import Bank of the United States (Parts 400--
                499)
         V  Office of Thrift Supervision, Department of the 
                Treasury (Parts 500--599)
        VI  Farm Credit Administration (Parts 600--699)
       VII  National Credit Union Administration (Parts 700--799)
      VIII  Federal Financing Bank (Parts 800--899)
        IX  Federal Housing Finance Board (Parts 900--999)
        XI  Federal Financial Institutions Examination Council 
                (Parts 1100--1199)
       XIV  Farm Credit System Insurance Corporation (Parts 1400--
                1499)
        XV  Department of the Treasury (Parts 1500--1599)
      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)

                    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--499)
         V  National Aeronautics and Space Administration (Parts 
                1200--1299)

                 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 Export Administration, Department of 
                Commerce (Parts 700--799)

[[Page 494]]

      VIII  Bureau of Economic Analysis, Department of Commerce 
                (Parts 800--899)
        IX  National Oceanic and Atmospheric Administration, 
                Department of Commerce (Parts 900--999)
        XI  Technology Administration, Department of Commerce 
                (Parts 1100--1199)
      XIII  East-West Foreign Trade Board (Parts 1300--1399)
       XIV  Minority Business Development Agency (Parts 1400--
                1499)
            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)

                    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  United States Customs Service, Department of the 
                Treasury (Parts 1--199)
        II  United States International Trade Commission (Parts 
                200--299)
       III  International Trade Administration, Department of 
                Commerce (Parts 300--399)

[[Page 495]]

                     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  Employment Standards Administration, 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, 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 Information Agency (Parts 500--599)
       VII  Overseas Private Investment Corporation (Parts 700--
                799)
        IX  Foreign Service Grievance Board Regulations (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  Board for International Broadcasting (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 496]]

                          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 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--999)
         X  Office of Assistant Secretary for Housing--Federal 
                Housing Commissioner, Department of Housing and 
                Urban Development (Interstate Land Sales 
                Registration Program) (Parts 1700--1799)
       XII  Office of Inspector General, Department of Housing and 
                Urban Development (Parts 2000--2099)
        XX  Office of Assistant Secretary for Housing--Federal 
                Housing Commissioner, Department of Housing and 
                Urban Development (Parts 3200--3899)
       XXV  Neighborhood Reinvestment Corporation (Parts 4100--
                4199)

[[Page 497]]

                           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--799)
         V  Bureau of Indian Affairs, Department of the Interior, 
                and Indian Health Service, Department of Health 
                and Human Services (Part 900)
        VI  Office of the Assistant Secretary-Indian Affairs, 
                Department of the Interior (Part 1001)
       VII  Office of the Special Trustee for American Indians, 
                Department of the Interior (Part 1200)

                      Title 26--Internal Revenue

         I  Internal Revenue Service, Department of the Treasury 
                (Parts 1--799)

           Title 27--Alcohol, Tobacco Products and Firearms

         I  Bureau of Alcohol, Tobacco and Firearms, Department of 
                the Treasury (Parts 1--299)

                   Title 28--Judicial Administration

         I  Department of Justice (Parts 0--199)
       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)

                            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)

[[Page 498]]

       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  Pension and Welfare Benefits 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  Minerals Management Service, Department of the 
                Interior (Parts 200--299)
       III  Board of Surface Mining and Reclamation Appeals, 
                Department of the Interior (Parts 300--399)
        IV  Geological Survey, Department of the Interior (Parts 
                400--499)
        VI  Bureau of Mines, Department of the Interior (Parts 
                600--699)
       VII  Office of Surface Mining Reclamation and Enforcement, 
                Department of the Interior (Parts 700--999)

                 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
         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 International Investment, Department of the 
                Treasury (Parts 800--899)

                      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)

[[Page 499]]

       VII  Department of the Air Force (Parts 800--1099)
            Subtitle B--Other Regulations Relating to National 
                Defense
       XII  Defense Logistics Agency (Parts 1200--1299)
       XVI  Selective Service System (Parts 1600--1699)
       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)
      XXIX  Presidential Commission on the Assignment of Women in 
                the Armed Forces (Part 2900)

               Title 33--Navigation and Navigable Waters

         I  Coast Guard, Department of Transportation (Parts 1--
                199)
        II  Corps of Engineers, Department of the Army (Parts 
                200--399)
        IV  Saint Lawrence Seaway Development Corporation, 
                Department of Transportation (Parts 400--499)

                          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 Vocational and Adult Education, Department 
                of Education (Parts 400--499)
         V  Office of Bilingual Education and Minority Languages 
                Affairs, Department of Education (Parts 500--599)
        VI  Office of Postsecondary Education, Department of 
                Education (Parts 600--699)
       VII  Office of Educational Research and Improvement, 
                Department of Education (Parts 700--799)
        XI  National Institute for Literacy (Parts 1100--1199)
            Subtitle C--Regulations Relating to Education
       XII  National Council on Disability (Parts 1200--1299)

[[Page 500]]

                        Title 35--Panama Canal

         I  Panama Canal Regulations (Parts 1--299)

             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)
       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)
       XIV  Assassination Records Review Board (Parts 1400--1499)

             Title 37--Patents, Trademarks, and Copyrights

         I  Patent and Trademark Office, Department of Commerce 
                (Parts 1--199)
        II  Copyright Office, Library of Congress (Parts 200--299)
        IV  Assistant Secretary for Technology Policy, Department 
                of Commerce (Parts 400--499)
         V  Under Secretary for Technology, Department of Commerce 
                (Parts 500--599)

           Title 38--Pensions, Bonuses, and Veterans' Relief

         I  Department of Veterans Affairs (Parts 0--99)

                       Title 39--Postal Service

         I  United States Postal Service (Parts 1--999)
       III  Postal Rate Commission (Parts 3000--3099)

                  Title 40--Protection of Environment

         I  Environmental Protection Agency (Parts 1--799)
         V  Council on Environmental Quality (Parts 1500--1599)
       VII  Environmental Protection Agency and Department of 
                Defense; Uniform National Discharge Standards for 
                Vessels of the Armed Forces (Parts 1700--1799)

          Title 41--Public Contracts and Property Management

            Subtitle B--Other Provisions Relating to Public 
                Contracts

[[Page 501]]

        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, Department of Labor 
                (Parts 61-1--61-999)
            Subtitle C--Federal Property Management Regulations 
                System
       101  Federal Property Management Regulations (Parts 101-1--
                101-99)
       105  General Services Administration (Parts 105-1--105-999)
       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)
            Subtitle D--Other Provisions Relating to Property 
                Management [Reserved]
            Subtitle E--Federal Information Resources Management 
                Regulations System
       201  Federal Information Resources Management Regulation 
                (Parts 201-1--201-99) [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 (Parts 303-1--303-2)
       304  Payment from a Non-Federal Source for Travel Expenses 
                (Parts 304-1--304-99)

                        Title 42--Public Health

         I  Public Health Service, Department of Health and Human 
                Services (Parts 1--199)
        IV  Health Care Financing Administration, Department of 
                Health and Human Services (Parts 400--499)
         V  Office of Inspector General-Health Care, Department of 
                Health and Human Services (Parts 1000--1999)

                   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 200--499)
        II  Bureau of Land Management, Department of the Interior 
                (Parts 1000--9999)

[[Page 502]]

       III  Utah Reclamation Mitigation and Conservation 
                Commission (Parts 10000--10005)

             Title 44--Emergency Management and Assistance

         I  Federal Emergency Management Agency (Parts 0--399)
        IV  Department of Commerce and Department of 
                Transportation (Parts 400--499)

                       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)
         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  Office of Human Development Services, 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 on Fine Arts (Parts 2100--2199)
      XXII  Christopher Columbus Quincentenary Jubilee Commission 
                (Parts 2200--2299)
     XXIII  Arctic Research Commission (Part 2301)
      XXIV  James Madison Memorial Fellowship Foundation (Parts 
                2400--2499)
       XXV  Corporation for National and Community Service (Parts 
                2500--2599)

[[Page 503]]

                          Title 46--Shipping

         I  Coast Guard, Department of Transportation (Parts 1--
                199)
        II  Maritime Administration, Department of Transportation 
                (Parts 200--399)
       III  Coast Guard (Great Lakes Pilotage), Department of 
                Transportation (Parts 400--499)
        IV  Federal Maritime Commission (Parts 500--599)

                      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)

           Title 48--Federal Acquisition Regulations System

         1  Federal Acquisition Regulation (Parts 1--99)
         2  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  United States 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  United States Information Agency (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)

[[Page 504]]

        34  Department of Education Acquisition Regulation (Parts 
                3400--3499)
        35  Panama Canal Commission (Parts 3500--3599)
        44  Federal Emergency Management Agency (Parts 4400--4499)
        51  Department of the Army Acquisition Regulations (Parts 
                5100--5199)
        52  Department of the Navy Acquisition Regulations (Parts 
                5200--5299)
        53  Department of the Air Force Federal Acquisition 
                Regulation Supplement (Parts 5300--5399)
        54  Defense Logistics Agency, Department of Defense (Part 
                5452)
        57  African Development Foundation (Parts 5700--5799)
        61  General Services Administration Board of Contract 
                Appeals (Parts 6100--6199)
        63  Department of Transportation Board of Contract Appeals 
                (Parts 6300--6399)
        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  Research and Special Programs Administration, 
                Department of Transportation (Parts 100--199)
        II  Federal Railroad Administration, Department of 
                Transportation (Parts 200--299)
       III  Federal Highway Administration, Department of 
                Transportation (Parts 300--399)
        IV  Coast Guard, Department of Transportation (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, Department of 
                Transportation (Parts 1000--1399)
        XI  Bureau of Transportation Statistics, Department of 
                Transportation (Parts 1400--1499)

                   Title 50--Wildlife and Fisheries

         I  United States Fish and Wildlife Service, Department of 
                the Interior (Parts 1--199)

[[Page 505]]

        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)
        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)

                      CFR Index and Finding Aids

            Subject/Agency Index
            List of Agency Prepared Indexes
            Parallel Tables of Statutory Authorities and Rules
            List of CFR Titles, Chapters, Subchapters, and Parts
            Alphabetical List of Agencies Appearing in the CFR



[[Page 507]]





           Alphabetical List of Agencies Appearing in the CFR




                      (Revised as of July 1, 1999)

                                                  CFR Title, Subtitle or 
                     Agency                               Chapter

Administrative Committee of the Federal Register  1, I
Advanced Research Projects Agency                 32, I
Advisory Commission on Intergovernmental          5, VII
     Relations
Advisory Committee on Federal Pay                 5, IV
Advisory Council on Historic Preservation         36, VIII
African Development Foundation                    22, XV
  Federal Acquisition Regulation                  48, 57
Agency for International Development, United      22, II
     States
  Federal Acquisition Regulation                  48, 7
Agricultural Marketing Service                    7, I, IX, X, XI
Agricultural Research Service                     7, V
Agriculture Department
  Agricultural Marketing Service                  7, I, IX, X, XI
  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
  Cooperative State Research, Education, and      7, XXXIV
       Extension Service
  Economic Research Service                       7, XXXVII
  Energy, Office of                               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
  Grain Inspection, Packers and Stockyards        7, VIII; 9, II
       Administration
  Information Resources Management, Office of     7, XXVII
  Inspector General, Office of                    7, XXVI
  National Agricultural Library                   7, XLI
  National Agricultural Statistics Service        7, XXXVI
  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 Telephone Bank                            7, XVI
  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                              32, VII
  Federal Acquisition Regulation Supplement       48, 53
Alcohol, Tobacco and Firearms, Bureau of          27, I
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

[[Page 508]]

Architectural and Transportation Barriers         36, XI
     Compliance Board
Arctic Research Commission                        45, XXIII
Armed Forces Retirement Home                      5, XI
Army Department                                   32, V
  Engineers, Corps of                             33, II; 36, III
  Federal Acquisition Regulation                  48, 51
Assassination Records Review Board                36, XIV
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
Board for International Broadcasting              22, XIII
Census Bureau                                     15, I
Central Intelligence Agency                       32, XIX
Chief Financial Officer, Office of                7, XXX
Child Support Enforcement, Office of              45, III
Children and Families, Administration for         45, II, III, IV, X
Christopher Columbus Quincentenary Jubilee        45, XXII
     Commission
Civil Rights, Commission on                       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                               44, IV
  Census Bureau                                   15, I
  Economic Affairs, Under Secretary               37, V
  Economic Analysis, Bureau of                    15, VIII
  Economic Development Administration             13, III
  Emergency Management and Assistance             44, IV
  Export Administration, Bureau of                15, VII
  Federal Acquisition Regulation                  48, 13
  Fishery Conservation and Management             50, VI
  Foreign-Trade Zones Board                       15, IV
  International Trade Administration              15, III; 19, III
  National Institute of Standards and Technology  15, II
  National Marine Fisheries Service               50, II, IV, VI
  National Oceanic and Atmospheric                15, IX; 50, II, III, IV, 
       Administration                             VI
  National Telecommunications and Information     15, XXIII; 47, III
       Administration
  National Weather Service                        15, IX
  Patent and Trademark Office                     37, I
  Productivity, Technology and Innovation,        37, IV
       Assistant Secretary for
  Secretary of Commerce, Office of                15, Subtitle A
  Technology, Under Secretary for                 37, V
  Technology Administration                       15, XI
  Technology Policy, Assistant Secretary for      37, IV
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 Product Safety Commission                5, LXXI; 16, II
Cooperative State Research, Education, and        7, XXXIV
     Extension Service
Copyright Office                                  37, II
Corporation for National and Community Service    45, XII, XXV
Cost Accounting Standards Board                   48, 99
Council on Environmental Quality                  40, V
Customs Service, United States                    19, I
Defense Contract Audit Agency                     32, I
Defense Department                                5, XXVI; 32, Subtitle A; 
                                                  40, VII
  Advanced Research Projects Agency               32, I
  Air Force Department                            32, VII

[[Page 509]]

  Army Department                                 32, V; 33, II; 36, III, 
                                                  48, 51
  Defense Intelligence Agency                     32, I
  Defense Logistics Agency                        32, I, XII; 48, 54
  Engineers, Corps of                             33, II; 36, III
  Federal Acquisition Regulation                  48, 2
  National Imagery and Mapping Agency             32, I
  Navy Department                                 32, VI; 48, 52
  Secretary of Defense, Office of                 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
Drug Enforcement Administration                   21, II
East-West Foreign Trade Board                     15, XIII
Economic Affairs, Under Secretary                 37, V
Economic Analysis, Bureau of                      15, VIII
Economic Development Administration               13, III
Economic Research Service                         7, XXXVII
Education, Department of                          5, LIII
  Bilingual Education and Minority Languages      34, V
       Affairs, Office 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
  Vocational and Adult Education, Office of       34, IV
Educational Research and Improvement, Office of   34, VII
Elementary and Secondary Education, Office of     34, II
Employees' Compensation Appeals Board             20, IV
Employees Loyalty Board                           5, V
Employment and Training Administration            20, V
Employment Standards Administration               20, VI
Endangered Species Committee                      50, IV
Energy, Department of                             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                   5, LIV; 40, I, 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
  Administration, Office of                       5, XV
  Environmental Quality, Council on               40, V
  Management and Budget, Office of                25, III, LXXVII; 48, 99
  National Drug Control Policy, Office of         21, III
  National Security Council                       32, XXI; 47, 2
  Presidential Documents                          3
  Science and Technology Policy, Office of        32, XXIV; 47, II
  Trade Representative, Office of the United      15, XX
       States
Export Administration, Bureau of                  15, VII
Export-Import Bank of the United States           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

[[Page 510]]

Federal Aviation Administration                   14, I
  Commercial Space Transportation                 14, III
Federal Claims Collection Standards               4, II
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                       11, I
Federal Emergency Management Agency               44, I
  Federal Acquisition Regulation                  48, 44
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; 49, III
Federal Home Loan Mortgage Corporation            1, IV
Federal Housing Enterprise Oversight Office       12, XVII
Federal Housing Finance Board                     12, IX
Federal Labor Relations Authority, and General    5, XIV; 22, XIV
     Counsel of the Federal Labor Relations 
     Authority
Federal Law Enforcement Training Center           31, VII
Federal Maritime Commission                       46, IV
Federal Mediation and Conciliation Service        29, XII
Federal Mine Safety and Health Review Commission  5, LXXIV; 29, XXVII
Federal Pay, Advisory Committee on                5, IV
Federal Prison Industries, Inc.                   28, III
Federal Procurement Policy Office                 48, 99
Federal Property Management Regulations           41, 101
Federal Property Management Regulations System    41, Subtitle C
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
Fine Arts, Commission on                          45, XXI
Fiscal Service                                    31, II
Fish and Wildlife Service, United States          50, I, IV
Fishery Conservation and Management               50, VI
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 Accounting Office                         4, I, II
General Services Administration                   5, LVII
  Contract Appeals, Board of                      48, 61
  Federal Acquisition Regulation                  48, 5
  Federal Property Management Regulations System  41, 101, 105
  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

[[Page 511]]

  Temporary Duty (TDY) Travel Allowances          41, 301
Geological Survey                                 30, IV
Government Ethics, Office of                      5, XVI
Government National Mortgage Association          24, III
Grain Inspection, Packers and Stockyards          7, VIII; 9, II
     Administration
Harry S. Truman Scholarship Foundation            45, XVIII
Health and Human Services, Department of          5, XLV; 45, Subtitle A
  Child Support Enforcement, Office of            45, III
  Children and Families, Administration for       45, II, III, IV, X
  Community Services, Office of                   45, X
  Family Assistance, Office of                    45, II
  Federal Acquisition Regulation                  48, 3
  Food and Drug Administration                    21, I
  Health Care Financing Administration            42, IV
  Human Development Services, Office of           45, XIII
  Indian Health Service                           25, V
  Inspector General (Health Care), Office of      42, V
  Public Health Service                           42, I
  Refugee Resettlement, Office of                 45, IV
Health Care Financing Administration              42, IV
Housing and Urban Development, Department of      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
  Inspector General, Office of                    24, XII
  Multifamily Housing Assistance Restructuring,   24, IV
       Office of
  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
Human Development Services, Office of             45, XIII
Immigration and Naturalization Service            8, I
Independent Counsel, Office of                    28, VII
Indian Affairs, Bureau of                         25, I, V
Indian Affairs, Office of the Assistant           25, VI
     Secretary
Indian Arts and Crafts Board                      25, II
Indian Health Service                             25, V
Information Agency, United States                 22, V
  Federal Acquisition Regulation                  48, 19
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
Institute of Peace, United States                 22, XVII
Inter-American Foundation                         5, LXIII; 22, X
Intergovernmental Relations, Advisory Commission  5, VII
     on
Interior Department
  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
  Minerals Management Service                     30, II
  Mines, Bureau of                                30, VI

[[Page 512]]

  National Indian Gaming Commission               25, III
  National Park Service                           36, I
  Reclamation, Bureau of                          43, I
  Secretary of the Interior, Office of            43, Subtitle A
  Surface Mining and Reclamation Appeals, Board   30, III
       of
  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, United States        22, II; 48, 7
       Agency for
  Overseas Private Investment Corporation         5, XXXIII; 22, VII
International Fishing and Related Activities      50, III
International Investment, Office of               31, VIII
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
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                                5, XXVIII; 28, I
  Drug Enforcement Administration                 21, II
  Federal Acquisition Regulation                  48, 28
  Federal Claims Collection Standards             4, II
  Federal Prison Industries, Inc.                 28, III
  Foreign Claims Settlement Commission of the     45, V
       United States
  Immigration and Naturalization Service          8, I
  Offices of Independent Counsel                  28, VI
  Prisons, Bureau of                              28, V
  Property Management Regulations                 41, 128
Labor Department                                  5, XLII
  Benefits Review Board                           20, VII
  Employees' Compensation Appeals Board           20, IV
  Employment and Training Administration          20, V
  Employment Standards Administration             20, VI
  Federal Acquisition Regulation                  48, 29
  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
  Pension and Welfare Benefits Administration     29, XXV
  Public Contracts                                41, 50
  Secretary of Labor, Office of                   29, Subtitle A
  Veterans' Employment and Training, Office of    41, 61; 20, IX
       the Assistant Secretary for
  Wage and Hour Division                          29, V
  Workers' Compensation Programs, Office of       20, I
Labor-Management Standards, Office of             29, II, IV
Land Management, Bureau of                        43, II
Legal Services Corporation                        45, XVI
Library of Congress                               36, VII
  Copyright Office                                37, II
Management and Budget, Office of                  5, III, LXXVII; 48, 99
Marine Mammal Commission                          50, V
Maritime Administration                           46, II
Merit Systems Protection Board                    5, II
Micronesian Status Negotiations, Office for       32, XXVII
Mine Safety and Health Administration             30, I
Minerals Management Service                       30, II
Mines, Bureau of                                  30, VI

[[Page 513]]

Minority Business Development Agency              15, XIV
Miscellaneous Agencies                            1, IV
Monetary Offices                                  31, I
Multifamily Housing Assistance Restructuring,     24, IV
     Office of
National Aeronautics and Space Administration     5, LIX; 14, V
  Federal Acquisition Regulation                  48, 18
National Agricultural Library                     7, XLI
National Agricultural Statistics Service          7, XXXVI
National Archives and Records Administration      5, LXVI; 36, XII
  Information Security Oversight Office           32, XX
National Bureau of Standards                      15, II
National Capital Planning Commission              1, IV
National Commission for Employment Policy         1, IV
National Commission on Libraries and Information  45, XVII
     Science
National and Community Service, Corporation for   45, XII, XXV
National Council on Disability                    34, XII
National Credit Union Administration              12, VII
National Drug Control Policy, Office of           21, III
National Foundation on the Arts and the           45, XI
     Humanities
National Highway Traffic Safety Administration    23, II, III; 49, V
National Imagery and Mapping Agency               32, I
National Indian Gaming Commission                 25, III
National Institute for Literacy                   34, XI
National Institute of Standards and Technology    15, II
National Labor Relations Board                    5, LXI; 29, I
National Marine Fisheries Service                 50, II, IV, VI
National Mediation Board                          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                       5, XLIII; 45, VI
  Federal Acquisition Regulation                  48, 25
National Security Council                         32, XXI
National Security Council and Office of Science   47, II
     and Technology Policy
National Telecommunications and Information       15, XXIII; 47, III
     Administration
National Transportation Safety Board              49, VIII
National Weather Service                          15, IX
Natural Resources Conservation Service            7, VI
Navajo and Hopi Indian Relocation, Office of      25, IV
Navy Department                                   32, VI
  Federal Acquisition Regulation                  48, 52
Neighborhood Reinvestment Corporation             24, XXV
Northeast Dairy Compact Commission                7, XIII
Nuclear Regulatory Commission                     5, XLVIII; 10, I
  Federal Acquisition Regulation                  48, 20
Occupational Safety and Health Administration     29, XVII
Occupational Safety and Health Review Commission  29, XX
Offices of Independent Counsel                    28, VI
Operations Office                                 7, XXVIII
Overseas Private Investment Corporation           5, XXXIII; 22, VII
Panama Canal Commission                           48, 35
Panama Canal Regulations                          35, I
Patent and Trademark Office                       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                                       22, III
Pennsylvania Avenue Development Corporation       36, IX
Pension and Welfare Benefits Administration       29, XXV
Pension Benefit Guaranty Corporation              29, XL
Personnel Management, Office of                   5, I, XXXV; 45, VIII
  Federal Acquisition Regulation                  48, 17
  Federal Employees Group Life Insurance Federal  48, 21
     Acquisition Regulation
[[Page 514]]

  Federal Employees Health Benefits Acquisition   48, 16
       Regulation
Postal Rate 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 Commission on the Assignment of      32, XXIX
     Women in the Armed Forces
Presidential Documents                            3
Presidio Trust                                    36, X
Prisons, Bureau of                                28, V
Procurement and Property Management, Office of    7, XXXII
Productivity, Technology and Innovation,          37, IV
     Assistant Secretary
Public Contracts, Department of Labor             41, 50
Public and Indian Housing, Office of Assistant    24, IX
     Secretary for
Public Health Service                             42, I
Railroad Retirement Board                         20, II
Reclamation, Bureau of                            43, I
Refugee Resettlement, Office of                   45, IV
Regional Action Planning Commissions              13, V
Relocation Allowances                             41, 302
Research and Special Programs Administration      49, I
Rural Business-Cooperative Service                7, XVIII, XLII
Rural Development Administration                  7, XLII
Rural Housing Service                             7, XVIII, XXXV
Rural Telephone Bank                              7, XVI
Rural Utilities Service                           7, XVII, XVIII, XLII
Saint Lawrence Seaway Development Corporation     33, IV
Science and Technology Policy, Office of          32, XXIV
Science and Technology Policy, Office of, and     47, II
     National Security Council
Secret Service                                    31, IV
Securities and Exchange Commission                17, II
Selective Service System                          32, XVI
Small Business Administration                     13, I
Smithsonian Institution                           36, V
Social Security Administration                    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
State Department                                  22, I
  Federal Acquisition Regulation                  48, 6
Surface Mining and Reclamation Appeals, Board of  30, III
Surface Mining Reclamation and Enforcement,       30, VII
     Office of
Surface Transportation Board                      49, X
Susquehanna River Basin Commission                18, VIII
Technology Administration                         15, XI
Technology Policy, Assistant Secretary for        37, IV
Technology, Under Secretary for                   37, V
Tennessee Valley Authority                        5, LXIX; 18, XIII
Thrift Supervision Office, Department of the      12, V
     Treasury
Trade Representative, United States, Office of    15, XX
Transportation, Department of                     5, L
  Coast Guard                                     33, I; 46, I; 49, IV
  Coast Guard (Great Lakes Pilotage)              46, III
  Commercial Space Transportation                 14, III
  Contract Appeals, Board of                      48, 63
  Emergency Management and Assistance             44, IV
  Federal Acquisition Regulation                  48, 12
  Federal Aviation Administration                 14, I
  Federal Highway Administration                  23, I, II; 49, III
  Federal Railroad Administration                 49, II
  Federal Transit Administration                  49, VI
  Maritime Administration                         46, II
  National Highway Traffic Safety Administration  23, II, III; 49, V
  Research and Special Programs Administration    49, I
  Saint Lawrence Seaway Development Corporation   33, IV

[[Page 515]]

  Secretary of Transportation, Office of          14, II; 49, Subtitle A
  Surface Transportation Board                    49, X
  Transportation Statistics Bureau                49, XI
Transportation, Office of                         7, XXXIII
Transportation Statistics Brureau                 49, XI
Travel Allowances, Temporary Duty (TDY)           41, 301
Treasury Department                               5, XXI; 12, XV; 17, IV
  Alcohol, Tobacco and Firearms, Bureau of        27, I
  Community Development Financial Institutions    12, XVIII
       Fund
  Comptroller of the Currency                     12, I
  Customs Service, United States                  19, I
  Engraving and Printing, Bureau of               31, VI
  Federal Acquisition Regulation                  48, 10
  Federal Law Enforcement Training Center         31, VII
  Fiscal Service                                  31, II
  Foreign Assets Control, Office of               31, V
  Internal Revenue Service                        26, I
  International Investment, Office of             31, VIII
  Monetary Offices                                31, I
  Secret Service                                  31, IV
  Secretary of the Treasury, Office of            31, Subtitle A
  Thrift Supervision, Office of                   12, V
Truman, Harry S. Scholarship Foundation           45, XVIII
United States and Canada, International Joint     22, IV
     Commission
United States and Mexico, International Boundary  22, XI
     and Water Commission, United States Section
Utah Reclamation Mitigation and Conservation      43, III
     Commission
Veterans Affairs Department                       38, I
  Federal Acquisition Regulation                  48, 8
Veterans' Employment and Training, Office of the  41, 61; 20, IX
     Assistant Secretary for
Vice President of the United States, Office of    32, XXVIII
Vocational and Adult Education, Office of         34, IV
Wage and Hour Division                            29, V
Water Resources Council                           18, VI
Workers' Compensation Programs, Office of         20, I
World Agricultural Outlook Board                  7, XXXVIII

[[Page 517]]



List of CFR Sections Affected



All changes in this volume of the Code of Federal Regulations which were 
made by documents published in the Federal Register since January 1, 
1986, 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 and parts as well as 
sections for revisions.
For the period before January 1, 1986, see the ``List of CFR Sections 
Affected, 1949-1963, 1964-1972, and 1973-1985'' which is published in 
seven separate volumes.

                                  1986

40 CFR
                                                                   51 FR
                                                                    Page
Chapter I
51  Nomenclature change............................................40661
51.1--51.8 (Subpart A)  Removed....................................40661
51.1  (nn) added...................................................11418
    Petitions denied...............................................15885
51.10  Removed.....................................................40661
51.11  Removed.....................................................40661
51.12  (m) and (n) added...........................................11418
    Petitions denied...............................................15885
    (e) through (i) redesignated as 51.110 (h) through (l); 
remainder of 51.12 removed.........................................40661
51.13--51.16  Removed..............................................40661
51.18  Petitions denied............................................15885
51.24  (l) revised.................................................32178
    Technical correction...........................................34086
    Redesignated as 51.166.........................................40661
51.30--51.34 (Subpart C)  Removed..................................40661
51.40  (a) and (b) amended.........................................40675
51.41  Amended.....................................................40675
51.54  (e) amended.................................................40675
51.61  (e) amended.................................................40675
51.80--51.88 (Subpart E)  Removed..................................40661
51.100--51.105 (Subpart F)  Added..................................40661
51.110--51.119 (Subpart G)  Added..................................40665
51.110  (h) through (l) redesignated from 51.12 (e) through (i)....40661
51.150--51.153 (Subpart H)  Added..................................40668
51.160--51.166 (Subpart I)  Heading added..........................40669
51.160--51.165  Added..............................................40669
51.166  Redesignated from 51.24....................................40661
    (a)(5), (b)(2)(iii)(e) (1) and (2), (f), (14)(i)(b) and 
(ii)(a), (15)(ii)(b), and (17), (f)(3), (g)(2)(i), and (i)(9) 
amended............................................................40675
51.210--51.214 (Subpart K)  Added..................................40673
51.230--51.232 (Subpart L)  Added..................................40673
51.260--51.262 (Subpart N)  Added..................................40674
51.280  Added......................................................40674
51.281  Added......................................................40674
51.340--51.341 (Subpart R)  Added..................................40674
51.327  Amended....................................................40675
51.328  Removed....................................................40675
51  Appendixes A through H, K, M, O, and R removed; Appendixes L, 
        P, and S amended...........................................40675

                                  1987

40 CFR
                                                                   52 FR
                                                                    Page
Chapter I
50.6  Revised; eff. 7-31-87........................................24663
    Technical correction...........................................26401
50.7  Removed; eff. 7-31-87........................................24664
    Technical correction...........................................26401
50  Appendix G amended; Appendix J added; eff. 7-31-87.............24664
    Appendix K  Added; eff. 7-31-87................................24667
    Technical correction...........................................26401
    Appendix K corrected....................................29382, 31701

[[Page 518]]

    Appendix J corrected...........................................29647
51  Authority citation revised.....................................24712
    State implementation plan attainment groups....................29383
51.100  (oo) through (ss) added; eff. 7-31-87......................24712
51.151  Amended; eff. 7-31-87......................................24731
51.165  (a)(1)(x) amended; and (b) revised; eff. 7-31-87...........24713
    Correctly designated...........................................29386
51.166  (a)(6)(i) and (i)(8)(i)(c), (f), (h), and (l) revised; 
        (b)(23)(i) and (c) table and (p)(4) table amended; (i)(10) 
        added; eff. 7-31-87........................................24713
    (i)(10) corrected..............................................29386
51.322  (a)(1) and (b)(1) revised; eff. 7-31-87....................24714
51.323  (a)(1) and (2) revised; (a)(3) added; eff. 7-31-87.........24714
51  Appendixes L and S amended; eff. 7-31-87.......................24714
    Appendix S corrected...........................................29386

                                  1988

40 CFR
                                                                   53 FR
                                                                    Page
Chapter I
50  Petition denied.........................................52698, 52705
51  Policy statement.................................................480
    Petition denied................................................52705
51.166  (l) revised..................................................396
    (b)(3)(iv), (13)(i), (ii) (a) and (b), (14)(i), (15)(i), 
(ii)(a), (c) tables, (f)(1)(v), (4)(i), and (p)(4) tables revised; 
(b)(14)(ii) redesignated as (b)(14)(iii); new (b)(14)(ii), 
(i)(11), and OMB number added; (p)(4) amended; eff. 10-17-89.......40670

                                  1989

40 CFR
                                                                   54 FR
                                                                    Page
Chapter I
51  PM 10 grouping revision........................................12620
    Air quality implementation plans...............................48870
51.165  (a)(1)(xiv) revised........................................27285
    (a)(1)(xix) added; (a)(3)(ii)(C) revised.......................27299
51.166  (b)(17) revised............................................27285
    (b)(29) and (s)(2)(vi) added; (s)(2)(iv)(b) removed; 
(s)(2)(iv)(c) redesignated as (s)(2)(iv)(b)........................27299
51  Appendix S amended......................................27285, 27299

                                  1990

40 CFR
                                                                   55 FR
                                                                    Page
Chapter I
51  Authority citation revised.....................................14249
    State implementation plan attainment groups.............38326, 45800
51.103  (a) introductory text revised...............................5830
51.212  (c) added..................................................14249
51  Appendix M added...............................................14249
    Appendix M corrected....................................24687, 37606
    Appendix V added................................................5830

                                  1991

40 CFR
                                                                   56 FR
                                                                    Page
Chapter I
51  Authority citation revised.....................................42219
51.166  (b)(23)(i) amended; eff. 8-12-91............................5506
51  Appendix M amended.......................................6278, 65435
    Appendix V amended......................................42219, 57288

                                  1992

40 CFR
                                                                   57 FR
                                                                    Page
Chapter I
Chapter I  Nomenclature change..............................28087, 28088
51  Authority citation revised..............................32334, 52987
51.100  (s) added...................................................3945
51.165  (a)(1)(xix) revised.........................................3946
    (a)(1)(xii)(D) revised; (a)(1)(v)(C)(8), (9), (xii)(E) and 
(xx) through (xxv added............................................32334
51.166  (b)(29) revised.............................................3946
    (b)(21)(iv) revised; (b)(2)(iii)(h) through (k), (21)(v) and 
(30) through (37) added............................................32335
51.350--51.373 (Subpart S)  Added..................................52987
51  Appendix S amended..............................................3946
    Appendix N removed.............................................52987

[[Page 519]]

                                  1993

40 CFR
                                                                   58 FR
                                                                    Page
Chapter I
50  National ambient air quality standards for ozone........13008, 21351
51  Sectional OMB numbers removed..................................34370
    Technical correction...........................................34904
    Authority citation revised.....................................38821
    Solid waste incinerator categories list........................58498
51.46  (b) revised, (c) removed; eff. 8-19-93......................38821
51.63  (a) amended; eff. 8-19-93...................................38821
51.112  (a) amended; (a)(1) and (a)(2) added; eff. 8-19-93.........38821
51.117  (c)(1), (2), and (3) amended; eff. 8-19-93.................38822
51.150  (e) amended; eff. 8-19-93..................................38822
51.160  (f)(1) and (2) added; eff. 8-19-93.........................38822
51.166  (b)(3)(iv), (i)(8)(i)(c), (c) table and (p)(4) table 
        revised; (f)(3) removed; (b)(14)(iv), (15)(iii) and 
        (i)(12) added; eff. 6-3-94.................................31636
    (l)(1) and (l)(2) revised; eff. 8-19-93........................38822
51.351  (a)(7)(iv), (v) and (vi) revised...........................59367
51.353  (a) amended................................................59367
51.359  (e)(1) amended.............................................59367
51.360  (a)(8) revised.............................................59367
51.373  (a) amended................................................59367
51.350--51.373 (Subpart S)  Appendixes A, D and E amended..........59367
51.390--51.464 (Subpart T)  Added..................................62216
51.850--51.860 (Subpart W)  Added (OMB number pending).............63247
51  Appendix W added; eff. 8-19-93.................................38822

                                  1994

40 CFR
                                                                   59 FR
                                                                    Page
Chapter I
50  Policy decision................................................38906
51.100  (s)(1) introductory text revised...........................50696
51.351  (v)  correctly revised.....................................32343
51.490--51.494 (Subpart U)  Added..................................16710
51  Appendix X added...............................................16715

                                  1995

40 CFR
                                                                   60 FR
                                                                    Page
Chapter I
51  Authority citation revised...............................1738, 40100
51.40--51.63 (Subpart D)  Removed..................................33922
51.100  (s)(1) introductory text revised...........................31637
51.105  Amended....................................................33922
51.111  (a), (b) and (c) removed; (d) redesignated as (a)..........33922
51.112  (a)(1) and (2) amended.....................................40468
51.113  Removed....................................................33922
51.120  Added.......................................................4736
51.160  (f)(1) and (2) amended.....................................40468
51.166  (l)(1) and (2) amended.....................................40468
51.213  (b) removed; (c) and (d) redesignated as (b) and (c).......33922
51.241  (a) amended................................................33922
51.340  Removed....................................................33922
51.350  (a)(4), (6), (7), (8), (9) and (b)(4) revised; (a)(5) 
        removed....................................................48034
51.351  (a) introductory text and (b) revised; (e) removed; (f) 
        and (g) added..............................................48035
51.360  Introductory text, (a)(1), (5), (6), (7) introductory 
        text, (9) and (b) revised..................................48036
51.372  (c), (d) and (e) added......................................1738
51.372  (c) introductory text, (3), (4) and (e) revised............48036
51.392  Amended....................................................57184
51.394  (b)(3)(i) revised; interim.................................44763
    (b)(3)(i) revised; (d) added...................................57184
51.396  (a) amended................................................57185
51.420  Revised....................................................57185
51.422  (a) amended; (d) added.....................................57185
51.428  (b)(1)(ii) revised.........................................57185
51.448  (b)(2) and (c)(2) redesignated as (b)(3) and (c)(3); 
        (a)(4), new (b)(2), new (c)(2) and (d)(4) added; new 
        (c)(3)(iii) amended; interim; eff. 2-8-95 through 8-8-95 
                                                                    7452
    (a)(3), (b)(1) introductory text and (d)(3) revised; (g)(1) 
and (2) removed; (b)(2), (c)(2) and (g)(3) redesignated as (b)(3), 
(c)(3) and (g)(1); new (b)(2) and (c)(2) added.....................40100
    (g) removed; (h) and (i) redesignated as (g) and (h); (a) 
through (d) and new (g) revised....................................57185
51.452  (b)(5) redesignated (a)(6); (c)(1) amended.................57186

[[Page 520]]

51  Appendix M amended.............................................28054
    Appendix U removed.............................................33922
51  Appendix W amended............................................40468,
40469, 40470, 40471

                                  1996

40 CFR
                                                                   61 FR
                                                                    Page
Chapter I
50  Decision.......................................................52852
50.4  Revised......................................................25579
50.5  Revised......................................................25580
51.100  (s)(1) introductory text revised............................4590
    (o) removed....................................................16060
    (o) added......................................................30162
    (s) introductory text and (1) revised..........................52850
51.101  Removed....................................................16060
    Added..........................................................30163
51.104  (a), (b) and (e) removed...................................16060
51.110  (a), (b), (c) and (e) through (l) removed; (d) 
        redesignated as (a)........................................16060
    (g) added......................................................30163
51.112  (a)(1) revised; (a)(2) amended.............................41840
51.160  (f)(1) revised; (f)(2) amended.............................41840
51.166  (b)(23)(i) amended..........................................9918
    (l)(1) revised; (l)(2) amended.................................41840
51.213  Removed....................................................16060
    Added..........................................................30163
51.241  (b) through (f) removed....................................16060
51.243  Removed....................................................16060
51.244  Removed....................................................16060
51.245  Removed....................................................16060
51.246  Removed....................................................16060
51.247  Removed....................................................16060
51.248  Removed....................................................16060
51.250  Removed....................................................16060
51.251  Removed....................................................16060
51.252  Removed....................................................16060
51.325  Removed....................................................16060
51.350  (b)(1) revised; (b)(5) added...............................39036
51.351  (h) added..................................................39036
    (c) added......................................................40945
51.352  (c) revised................................................40945
51.353  (c)(5) added...............................................39037
51.357  (a)(12) and (b)(4) added...................................40945
51.358  (b)(4) added...............................................40945
51.361  Introductory text and (b)(1)(i) revised....................49682
51.364  (e) and (f) added..........................................39037
51.365  (a)(23) and (24) amended; (a)(25) added....................40945
51.366  (a)(2)(ix) amended; (a)(2)(xi) through (xxiii) added.......40945
51.372  (b)(3) revised.............................................40946
    (b)(3) corrected...............................................44119
51.373  (f) added..................................................39037
    (g) added......................................................40946
51.350--51.373 (Subpart S)  Appendix B amended.....................40946
51  Appendix W revised.............................................41840

                                  1997

40 CFR
                                                                   62 FR
                                                                    Page
Chapter I
50  Announcement...................................................38762
    Comment period extension.......................................43642
50.3  Revised......................................................38711
50.6  Heading revised; (d) added...................................38711
50.7  Added........................................................38711
50.9  Revised......................................................38894
50.10  Added.......................................................38894
50  Appendix K revised.............................................38712
    Appendix L added...............................................38714
    Appendix M added...............................................38753
    Appendix N added...............................................38755
    Appendixes D and H amended; Appendix E removed; Appendix I 
added..............................................................38895
51  Authority citation revised........................8328, 43801, 44903
51.100  (s) introductory text and (1) revised......................44903
51.212  (c) revised.................................................8328
51.390 (Subpart T)  Revised........................................43801
51  Appendix M amended.............................................32502

                                  1998

40 CFR
                                                                   63 FR
                                                                    Page
Chapter I
50  Notice..........................................................6032
    Authority citation revised......................................7274
50.1  (i) added.....................................................7274
50.2  (c) and (d) revised...........................................7274
50  Appendix L corrected............................................7710
51  Technical correction............................................6483
    Authority citation revised.....................................24433
51.100  (o)(3) revised..............................................9151
    (s)(1) revised.................................................17333
51.103  (a) amended; (a)(1) and (2) removed.........................9151
51.121  Added......................................................57491

[[Page 521]]

    (e)(4) introductory text and (f)(2)(ii) revised................71225
51.122  Added......................................................57496
51.212  Regulation at 62 FR 8328 eff. date corrected to 12-30-97 
                                                                     414
51.351  (c) revised................................................24433
51.352  (c) revised................................................24433
51.353  (c)(3) and (4) revised......................................1368
51.357  (b)(4) revised.............................................24433
51.361  Regulation at 61 FR 49682 eff. date corrected to 2-10-98 
                                                                    6645
51.373  (g) revised................................................24433

                                  1999

   (Regulations published from January 1, 1999, through July 1, 1999)

40 CFR
                                                                   64 FR
                                                                    Page
Chapter I
50  Appendix L amended.............................................19719
51  Authority citation revised.....................................35763
51.121  (e)(2), (3)(iii) and (g)(2)(ii) revised....................26305
51.300  (a), (b)(1) introductory text and (2) revised; (b)(3) 
        added; eff. 8-30-99........................................35763
51.301  Amended; eff. 8-30-99......................................35763
    (v) amended; eff. 8-30-99......................................35774
51.302  Heading, (a), (c) introductory text, (1), (2) introductory 
        text, (4) introductory text and (iv) revised; eff. 8-30-99
                                                                   35764
    (c)(2)(i) and (4)(i) amended; eff. 8-30-99.....................35774
51.303  (a)(1), (c), (d), (g) and (h) amended; eff. 8-30-99........35774
51.304  (c) amended; eff. 8-30-99..................................35774
51.305  Heading and (a) revised; eff. 8-30-99......................35764
51.306  Heading, (a)(1), (c) introductory text and (d) revised; 
        eff. 8-30-99...............................................35764
    (a)(1) and (c)(6) amended; eff. 8-30-99........................35774
51.307  (a) introductory text, (2) and (c) revised; eff. 8-30-99 
                                                                   35765
    (b)(1) and (c) amended; eff. 8-30-99...........................35774
51.308  Added; eff. 8-30-99........................................35765
51.309  Added; eff. 8-30-99........................................35769
51.322  (a)(1) and (2) revised......................................7462
51.323  (a)(2) removed; (a)(1), (3) and (b) revised.................7463
51  Appendixes M and P corrected; CFR correction....................5188


                                  
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