[Federal Register Volume 64, Number 12 (Wednesday, January 20, 1999)]
[Rules and Regulations]
[Pages 3030-3037]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-1125]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 58

[AD-FRL-6221-2]
RIN 2060-AF71


Ambient Air Quality Surveillance for Lead

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: Lead air pollution levels measured near the Nation's roadways

[[Page 3031]]

have decreased 97 percent between 1978 and 1997 with the elimination of 
lead in gasoline used by on-road mobile sources. Because of this 
historic decrease, EPA is reducing its requirements for measuring lead 
air pollutant concentrations near major highways, while retaining its 
focus on point sources and their impact on neighboring populations. The 
EPA published a direct final rule for ambient air quality surveillance 
for lead on November 5, 1997 (62 FR 59813). Due to adverse comments 
received, the rule was withdrawn on December 23, 1997 (62 FR 67009). 
Based on comments that were received, today's action revises 40 CFR 
part 58 lead air monitoring regulations to allow many lead monitoring 
stations to be discontinued while maintaining a core lead monitoring 
network in urban areas to track continued compliance with the lead 
National Ambient Air Quality Standards (NAAQS). This action does not 
diminish existing requirements for lead ambient air monitoring around 
lead point sources. Approximately 70 of the National Air Monitoring 
Stations (NAMS) and a number of the State and Local Air Monitoring 
Stations (SLAMS) could be discontinued with this action, thus making 
more resources available to those State and local agencies to deploy 
lead air quality monitors around heretofore unmonitored lead point 
sources. Affected industries include primary and secondary lead 
smelting, lead battery recycling, and primary copper smelting.

DATES: The effective date of this rule is February 19, 1999.

ADDRESSES: All comments relative to this rule have been placed in 
Docket No. A-91-22, located in the Air Docket (LE-131), U.S. 
Environmental Protection Agency, 401 M Street, SW, Washington, DC 
20460. The docket may be inspected between 8 a.m. and 5:30 p.m., Monday 
through Friday, excluding legal holidays. A reasonable fee may be 
charged for copying.

FOR FURTHER INFORMATION CONTACT: For general information, contact 
Brenda Millar, Emissions, Monitoring, and Analysis Division (MD-14), 
Office of Air Quality Planning and Standards, U.S. Environmental 
Protection Agency, Research Triangle Park, North Carolina 27711, 
Telephone: (919) 541-4036, e-mail: [email protected]. For technical 
information, contact Michael Jones, Emissions Monitoring, and Analysis 
Division (MD-14), Office of Air Quality Planning and Standards, U.S. 
Environmental Protection Agency, Research Triangle Park, North Carolina 
27711, Telephone: (919) 541-0528, e-mail: [email protected].

SUPPLEMENTARY INFORMATION:

I. Authority

    Sections 110, 301(a), and 319 of the Clean Air Act as amended 42 
U.S.C. 7410, 7601(a), 7619.

II. Background

    The current ambient air monitoring regulations that pertain to lead 
air sampling were written in the 1970's when lead emissions from on-
road mobile sources (e.g., automobiles, trucks) were the predominant 
lead air emission source affecting our communities. As such, the 
current lead monitoring requirements focus primarily upon the idea of 
determining the air quality impacts from major roadways and urban 
traffic arterial highways. Since the 1970's, lead has been removed from 
gasoline sources for on-road vehicles (on-road vehicles now account for 
less than 1 percent of total lead emissions), and a 97 percent decrease 
in lead air pollution levels measured in our neighborhoods and near 
roadways has occurred nationwide. Because of this historic decrease, 
EPA is reducing its requirements for measuring lead air pollutant 
concentrations near major highways, while retaining its focus on point 
sources and their impacts on neighboring populations.
    Several commenters observed that the rule's assessment of on-road 
vehicles emissions is contrary to the Agency's own figures. 
Specifically, the proposed rule stated that on-road vehicle emissions 
account for less than 1 percent of total lead emissions, while the 
Agency's 1995 National Air Quality and Emissions Trends Report (EPA 
454/R-96-005) indicated that nearly 28 percent of total air lead 
emissions were attributable to on-road vehicles.
    Based on the emissions reported in ``Locating and Estimating Air 
Emissions from Sources of Lead and Lead Compounds'' (Eastern Research 
Group, Draft Report, July 1996), on-road vehicle emissions had been 
over estimated. The EPA investigated this inconsistency and found due 
cause to revise on-road vehicle emissions estimates. These revisions 
are reflected in subsequent Agency reports (e.g., EPA 454/R-97-011, 
``National Air Pollutant Emission Trends, 1900-1996'', EPA 454/R-97013, 
``National Air Quality and Trends Report, 1996,'' and EPA 454/R-98-016, 
``National Air Quality and Trends Report, 1997'') wherein on-road 
vehicle emissions are listed as contributing approximately 0.5 percent 
of the total lead estimate.
    Several commenters questioned the rule's asserted need for 
additional monitors around stationary point sources, particularly the 
basis for increased scrutiny of stationary sources emitting five or 
more tons per year, as well as, in select cases, those sources emitting 
less than 5 tons per year. Further, the potential for increased 
information collection burden, and means of determining which ``smaller 
stationary sources'' would be considered ``problematic'' were also 
questioned.
    The primary objective of this rule is to reduce the requirement for 
lead air pollutant concentration measurements near major highways, 
while maintaining a focus on lead point sources and their impact on 
neighboring populations. The EPA has determined that, in the interest 
of furthering attainment of the National Ambient Air Quality Standard 
(NAAQS) for lead, it is prudent for State and local agencies to deploy 
these additional lead monitoring resources in the vicinity of any 
previously unmonitored point source which they feel may have the 
potential to cause lead air quality violations. A point source is 
defined in 40 CFR 51.100(k)(2) as ``For lead or lead compounds measured 
as lead, any stationary source that actually emits a total of 4.5 
metric tons (5 tons) per year or more.'' Though the verbiage `` * * * 
although smaller stationary sources may also be problematic depending 
upon the facility's size and proximity to neighborhoods' was removed 
from this rule, State and local agencies are not precluded from further 
evaluating any lead source which they feel may have the potential to 
violate lead air quality standards. Suggested guidelines for such 
source evaluations are described in ``Screening Procedures for 
Estimating the Air Quality Impact of Stationary Sources, Revised'' (EPA 
454/R-92-019). Finally, ambient lead monitoring occurs at existing 
major primary and secondary lead smelters, lead acid battery plants, 
and primary copper smelters. As essentially all quantifiable lead point 
sources are included in these categories, and considering the 
substantial decrease in roadside monitoring which will result from this 
rule, EPA believes this rule will entail little or no increased 
information collection burden.
    A State requested that EPA amend the referenced rule to delete the 
requirement for one NAMS population-oriented site in the vicinity of a 
specific facility within their jurisdiction.
    The monitoring site north of the facility in question has reported 
lead NAAQS violations in 1 or 2 quarters during each of the past 3 
years. Given that this monitor is sited at the middle

[[Page 3032]]

scale, it is not unreasonable to require a NAMS site on the 
neighborhood scale. Data from such a site are useful in representing 
typical air quality values for nearby residential areas, and suitable 
for population exposure and trends analysis.
    The current lead air monitoring regulations require that each 
urbanized area with a population of 500,000 or more operate at least 
two lead NAMS, one of which must be a roadway-oriented site and the 
second must be a neighborhood site with nearby traffic arteries or 
other major roadways. There are approximately 58 NAMS in operation and 
reporting data for 1998. This action would change this NAMS requirement 
to include one NAMS site in one of the two largest Metropolitan 
Statistical Areas (MSA/CMSA) within each of the ten EPA Regions, and 
one NAMS population-oriented site in each populated area (either a MSA/
CMSA, town, or county) where lead violations have been measured over 
the most recent 8 calendar quarters. This latter requirement is 
designed to provide information to citizens living in areas that have 
one or more lead point sources that are causing recent air quality 
violations. At present, the MSA/CMSAs, cities, or counties that have 
one or more quarterly Pb NAAQS violations that may be subject to this 
requirement are listed in Table 1.

 Table 1.--CMSA/MSA's or Counties With One or More Lead NAAQS Violations
                              in 1996-1997
------------------------------------------------------------------------
           CMSA/MSA or County              Contributing Lead Source(s)
------------------------------------------------------------------------
Philadelphia-Wilmington-Atlantic City    Franklin Smelter in
 CMSA.                                    Philadelphia County, PA.
Tampa-St. Petersburg-Clearwater MSA....  Gulf Coast Lead in Hillsborough
                                          County, FL.
Memphis MSA............................  Refined Metals in Shelby
                                          County, TN.
Nashville MSA..........................  General Smelting in Williamson
                                          County, TN.
St. Louis MSA..........................  Chemetco in Madison County, IL,
                                          and Doe Run in Jefferson
                                          County, MO.
Cleveland-Akron CMSA...................  Master Metals in Cuyahoga
                                          County, OH.
Iron County, MO........................  ASARCO in/near Hogan, MO.
Omaha MSA..............................  ASARCO in Douglas County, NE.
Lewis and Clark County, MT.............  ASARCO in/near East Helena, MT.
------------------------------------------------------------------------

    Data from these NAMS will be used to assess national trends in lead 
ambient air pollution. Figure 1 demonstrates the effect that these 
monitoring reductions will have on our national lead air pollutant 
trends.
[GRAPHIC] [TIFF OMITTED] TR20JA99.001


    For other monitoring within the SLAMS network, EPA is allowing 
State and local agencies to further focus their efforts toward 
establishing air monitoring networks around lead point sources which 
are causing or have a potential to cause exceedances of the quarterly 
lead NAAQS. Many of these sources have been identified through EPA's 
ongoing Lead NAAQS Attainment Strategy, and monitoring has already been 
established. All point sources (stationary sources emitting five or 
more tons per year) are considered to be candidates for additional lead 
monitoring . The EPA recommends a minimum of two sites per source, one 
located for stack emission impacts and the other for fugitive emission 
impacts. Variations of this two-site network are expected as source 
type, topography,

[[Page 3033]]

locations of neighboring populations, and other factors play a role in 
how to most appropriately design such a network. EPA guidance for lead 
monitoring around point sources has been developed and is available 
through a variety of sources including the National Technical 
Information Service (800-553-6847), and electronic forms accessible 
through EPA's Office of Air Quality Planning & Standards Technology 
Transfer Network, Ambient Monitoring Technology Information Center 
(AMTIC) bulletin board system at http://ttnwww.rtpnc.epa.gov.
    One commenter questioned the rule's consistency with statutory 
mandates under section 319 of the Clean Air Act (CAA), in particular by 
citing the requirement for ``uniform air quality criteria * * * 
throughout the United States.'' 42 U.S.C. 7619.
    In section 319 of the CAA, the term ``criteria'' refers to a 
specific set of pollutants and the associated levels and forms of their 
respective standards. The term ``uniform'' refers to both criteria and 
measurement methodology, relative to a specific air quality index. 
Uniformity in ambient monitoring is achieved by monitor design 
specifications (40 CFR part 53) and quality assurance/quality control 
procedures. Monitors which meet such design specifications are 
designated as either Federal Reference Method (FRM) or Federal 
Equivalent Method (FEM), as appropriate. Further, upon reading the 
entire text of the CAA, section 319, from which the commenter's excerpt 
was taken, it becomes clear that the new rule is, in fact, consistent 
with the referenced statutory mandates.
    Several commenters noted that this rule is being issued in response 
to numerous State and local agency requests, yet the docket contains no 
documentation of such requests.
    As many roadside monitored ambient lead values have steadily 
declined to at or near minimally detectable levels, the need for 
continued roadside ambient lead monitoring has been increasingly and 
repeatedly questioned by State representatives at the biannual Standing 
Air Monitoring Work Group meetings, as well as several instances of 
written queries and requests. The reason the Agency did not include any 
such existing documentation in the docket is that the basis for this 
rule revision is not requests from State and local agencies, but rather 
EPA's success in essentially eliminating on-road mobile source lead 
emissions. Given the fact that on-road mobile sources' contribution to 
the total lead emissions estimate is negligible, as evidenced by 
minimally detectable ambient levels at all locations other than sites 
in proximity to lead point sources, it is EPA's inherent responsibility 
to ensure our nation's ambient air pollution monitoring resources are 
redirected toward environmental issues of concern.
    Several commenters expressed concern over potential data misuse in 
commencement of unjustified enforcement proceedings or citizen suits. 
The reason for concern was cited as the combined impact of the proposed 
revisions to 40 CFR part 58 and EPA's Credible Evidence revisions to 40 
CFR parts 51, 52, 60, and 61.
    The referenced Credible Evidence revisions and related amendments 
to 40 CFR part 64, Compliance Assurance Monitoring, pertain exclusively 
to emissions monitoring data, not ambient air quality data. The 
proposed revisions to 40 CFR part 58, Ambient Air Quality Surveillance, 
do not allow for use of non-reference data in any compliance or 
enforcement actions. There is, therefore, no plausible potential for 
data misuse in commencement of unjustified enforcement proceedings or 
citizen suits.
    In addition to the changes to the lead monitoring requirements, EPA 
is making several minor changes to update and correct regulatory 
provisions to current practices. Specifically this affects Secs. 58.31, 
58.34, 58.41, Appendix B, Appendix D Sections 3.2 and 3.3, and Appendix 
G, Sections 1 and 2b.

III. Administrative Requirements

A. Executive Order 12866

    Under Executive Order 12866 (58 F.R. 51735, October 4, 1993), the 
Agency must determine whether the regulatory action is ``significant'' 
and therefore subject to Office of Management and Budget (OMB) review 
and to the requirements of the Executive Order. The Order defines 
``significant regulatory action'' as one that is likely to result in a 
rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local, or governments or communities;
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another Agency;
    (3) Materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of recipients 
thereof; or
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    It has been determined that this action is not a ``significant 
regulatory action'' under the terms of the Executive Order 12866 and is 
therefore not subject to formal OMB review.

B. Paperwork Reduction Act

    Today's action does not impose any new information collection 
burden. This action revises the part 58 air monitoring regulations for 
lead to allow many monitoring sites to be discontinued. The Office of 
Management and Budget (OMB) has previously approved the information 
collection requirements in the part 58 regulation under the provisions 
of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. and has assigned 
OMB control number 2060-0084 (EPA ICR No. 0940.13 and revised by 
0940.14).

C. Executive Order 12875 Enhancing the Intergovernmental Partnership

    Under Executive Order 12875, EPA may not issue a regulation that is 
not required by statute and that creates a mandate upon a State, local 
or tribal government, unless the Federal government provides the funds 
necessary to pay the direct compliance costs incurred by those 
governments, or EPA consults with those governments. If EPA complies by 
consulting, Executive Order 12875 requires EPA to provide to the Office 
of Management and Budget a description of the extent of EPA's prior 
consultation with representatives of affected State, local and tribal 
governments, the nature of their concerns, copies of any written 
communications from the governments, and a statement supporting the 
need to issue the regulation. In addition, Executive Order 12875 
requires EPA to develop an effective process permitting elected 
officials and other representatives of State, local and tribal 
governments ``to provide meaningful and timely input in the development 
of regulatory proposals containing significant unfunded mandates.''
    Today's rule implements requirements specifically set forth by the 
Congress in 42 U.S.C. 7410 without the exercise of any discretion by 
EPA. Accordingly, the requirements of section 1(a) of Executive Order 
12875 do not apply to this rule.

D. Executive Order 13045

    Executive Order 13045, entitled ``Protection of Children from 
Environmental Health Risks and Safety Risks'' (62 FR 19885, April 23, 
1997), applies to any rule that the EPA determines (1) is 
``economically significant,'' as defined under Executive Order 12866, 
and (2) the environmental

[[Page 3034]]

health or safety risk addressed by the rule has a disproportionate 
effect on children. If the regulatory action meets both criteria, the 
Agency must evaluate the environmental health or safety effects of the 
planned rule on children and explain why the planned regulation is 
preferable to other potentially effective and reasonably feasible 
alternatives considered by the Agency.
    This rule is not subject to Executive Order 13045 because it is not 
an economically significant regulatory action as defined by Executive 
Order 12866, and it does not address an environmental health or safety 
risk that would have a disproportionate effect on children.

E. Executive Order 13084 Consultation and Coordination With Indian 
Tribal Governments

    Under Executive Order 13084, EPA may not issue a regulation that is 
not required by statute, that significantly or uniquely affects the 
communities of Indian tribal governments, and that imposes substantial 
direct compliance costs on those communities, unless the Federal 
government provides the funds necessary to pay the direct compliance 
costs incurred by the tribal governments, or EPA consults with those 
governments. If EPA complies by consulting, Executive Order 13084 
requires EPA to provide to the Office of Management and Budget, in a 
separately identified section of the preamble to the rule, a 
description of the extent of EPA's prior consultation with 
representatives of affected tribal governments, a summary of the nature 
of their concerns, and a statement supporting the need to issue the 
regulation. In addition, Executive Order 13084 requires EPA to develop 
an effective process permitting elected officials and other 
representatives of Indian tribal governments ``to provide meaningful 
and timely input in the development of regulatory policies on matters 
that significantly or uniquely affect their communities.''
    Today's rule does not significantly or uniquely affect the 
communities of Indian tribal governments. Accordingly, the requirements 
of section 3(b) of Executive Order 13084 do not apply to this rule.

F. Impact on Small Entities

    The Regulatory Flexibility Act (RFA) generally requires an agency 
to conduct a regulatory flexibility analysis of any rule subject to 
notice and comment rulemaking requirements unless the agency certifies 
that the rule will not have a significant economic impact on a 
substantial number of small entities. Small entities include small 
businesses, small not-for-profit enterprises, and small governmental 
jurisdictions whose jurisdictions are less than 50,000 people. This 
rule will not have a significant impact on a substantial number of 
small entities because it does not impact small entities whose 
jurisdictions cover less than 50,000 people. Pursuant to the provision 
of 5 U.S.C. 605(b), I certify that this action will not have a 
significant economic impact on a substantial number of small entities.
    Since this modification is classified as minor, no additional 
reviews are required.

G. Unfunded Mandates Reform Act of 1995

    Under section 202 of the Unfunded Mandates Reform Act of 1995 
(``Unfunded Mandates Act''), signed into law on March 22, 1995, EPA 
must prepare a budgetary impact statement to accompany any proposed or 
final standards that include a Federal mandate that may result in 
estimated costs to State, local, or tribal governments, or to the 
private sector, of, in the aggregate, $100 million or more. Under 
section 205, the EPA must select the most cost-effective and least 
burdensome alternative that achieves the objectives of the standard and 
is consistent with statutory requirements. Section 203 requires EPA to 
establish a plan for informing and advising any small governments that 
may be significantly or uniquely impacted by the standards. The EPA has 
determined that this action does not include a Federal mandate that may 
result in estimated costs of $100 million or more to either State, 
local, or tribal governments. Therefore, the requirements of the 
Unfunded Mandates Act of 1995 do not apply to this action.

H. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (NTTAA), Pub. L. No. 104-113, 12(d) (15 U.S.C. 272 note) 
directs EPA to use voluntary consensus standards in its regulatory 
activities unless to do so would be inconsistent with applicable law or 
otherwise impractical. Voluntary consensus standards are technical 
standards (e.g., materials specifications, test methods, sampling 
procedures, and business practices) that are developed or adopted by 
voluntary consensus standards bodies. The NTTAA directs EPA to provide 
Congress, through OMB, explanations when the Agency decides not to use 
available and applicable voluntary consensus standards.
    This action does not involve technical standards. Therefore, EPA 
did not consider the use of any voluntary consensus standards.

I. Submission to Congress and the General Accounting Office

    The Congressional Review Act, U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the Agency promulgating 
the rule must submit a rule report, which includes a copy of the rule 
to each House of the Congress and to the Comptroller General of the 
United States. EPA will submit a report containing this rule and other 
required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. This rule is not a 
``major rule'' as defined by 5 U.S.C. 804(2).

List of Subjects in 40 CFR Part 58

    Environmental protection, Air pollution control, Intergovernmental 
relations, Reporting and recordkeeping requirements, Quality assurance 
requirements, Ambient air quality monitoring network.

    Dated: January 12, 1999.
Carol M. Browner,
Administrator.
    For the reasons set forth in the preamble, title 40, chapter I, 
part 58 of the Code of Federal Regulations is amended as follows:

PART 58--[AMENDED]

    1. The authority citation for part 58 continues to read as follows:

    Authority: 42 U.S.C. 7410, 7601(a), 7613, 7619.

    2. Section 58.31(a) is revised to read as follows:


Sec. 58.31  NAMS network description.

* * * * *
    (a) The AIRS site identification number for existing stations.
* * * * *
    3. Section 58.34(a) is revised to read as follows:


Sec. 58.34  NAMS network completion.

* * * * *
    (a) Each NAMS must be in operation, be sited in accordance with the 
criteria in Appendix E to this part, and be located as described in the 
AIRS database; and
* * * * *

[[Page 3035]]

    4. Section 58.41(b) is revised to read as follows:


Sec. 58.41  PAMS network description.

* * * * *
    (b) The AIRS site identification number for existing stations.
* * * * *
    5. Appendix D is amended by revising the first sentence of the 
undesignated paragraph following paragraph (6) of section 1, revising 
section 2.7, revising the fifth paragraph of section 3, revising the 
last sentence of the first paragraph of section 3.2, revising the last 
sentence of the first paragraph of section 3.3, revising section 3.6, 
and revising references 6, 7, 10 of section 6 and adding reference 19 
to section 6 to read as follows:

Appendix D--Network Design for State and Local Air Monitoring 
Stations (SLAMS), National Air Monitoring Stations (NAMS), and 
Photochemical Assessment Monitoring Stations (PAMS)

* * * * *

1. SLAMS Monitoring Objectives and Spatial Scales

 * * * * *
    It should be noted that this appendix contains no criteria for 
determining the total number of stations in SLAMS networks, except 
in areas where Pb concentrations currently exceed or have exceeded 
the Pb NAAQS during any one quarter of the most recent eight 
quarters. * * *
* * * * *
    2.7  Lead (Pb) Design Criteria for SLAMS. Presently, less than 1 
percent of the Nation's Pb air pollution emissions originate from 
on-road mobile source exhaust. The majority of Pb emissions come 
from point sources, such as metals processing facilities, waste 
disposal and recycling, and fuel combustion (reference 19 of this 
appendix). The SLAMS networks are used to assess the air quality 
impacts of Pb point sources, and to determine the broad population 
exposure from any Pb source. The most important spatial scales to 
effectively characterize the emissions from point sources are the 
micro, middle, and neighborhood scales. For purposes of establishing 
monitoring stations to represent large homogeneous areas other than 
the above scales of representativeness, urban or regional scale 
stations may also be needed.
    Microscale--This scale would typify areas in close proximity to 
lead point sources. Emissions from point sources such as primary and 
secondary lead smelters, and primary copper smelters may under 
fumigation conditions likewise result in high ground level 
concentrations at the microscale. In the latter case, the microscale 
would represent an area impacted by the plume with dimensions 
extending up to approximately 100 meters. Data collected at 
microscale stations provide information for evaluating and 
developing ``hot-spot'' control measures.
    Middle Scale--This scale generally represents Pb air quality 
levels in areas up to several city blocks in size with dimensions on 
the order of approximately 100 meters to 500 meters. The middle 
scale may for example, include schools and playgrounds in center 
city areas which are close to major Pb point sources. Pb monitors in 
such areas are desirable because of the higher sensitivity of 
children to exposures of elevated Pb concentrations (reference 7 of 
this appendix). Emissions from point sources frequently impact on 
areas at which single sites may be located to measure concentrations 
representing middle spatial scales.
    Neighborhood Scale--The neighborhood scale would characterize 
air quality conditions throughout some relatively uniform land use 
areas with dimensions in the 0.5 to 4.0 kilometer range. Stations of 
this scale would provide monitoring data in areas representing 
conditions where children live and play. Monitoring in such areas is 
important since this segment of the population is more susceptible 
to the effects of Pb. Where a neighborhood site is located away from 
immediate Pb sources, the site may be very useful in representing 
typical air quality values for a larger residential area, and 
therefore suitable for population exposure and trends analyses.
    Urban Scale--Such stations would be used to present ambient Pb 
concentrations over an entire metropolitan area with dimensions in 
the 4 to 50 kilometer range. An urban scale station would be useful 
for assessing trends in citywide air quality and the effectiveness 
of larger scale air pollution control strategies.
    Regional Scale--Measurements from these stations would 
characterize air quality levels over areas having dimensions of 50 
to hundreds of kilometers. This large scale of representativeness, 
rarely used in Pb monitoring, would be most applicable to sparsely 
populated areas and could provide information on background air 
quality and inter-regional pollutant transport.
    Monitoring for ambient Pb levels is required for all major 
urbanized areas where Pb levels have been shown or are expected to 
be of concern due to the proximity of Pb point source emissions. 
Sources emitting five tons per year or more of actual point and 
fugitive Pb emissions would generally be candidates for lead ambient 
air monitoring. Modeling may be needed to determine if a source has 
the potential to exceed the quarterly lead National Ambient Air 
Quality Standards (NAAQS). The total number and type of stations for 
SLAMS are not prescribed but must be determined on a case-by-case 
basis. As a minimum, there must be two stations in any area where Pb 
concentrations currently exceed or have exceeded the Pb NAAQS during 
any one quarter of the most recent eight quarters. Where the Pb air 
quality violations are widespread or the emissions density, 
topography, or population locations are complex and varied, there 
may be a need to establish more than two Pb ambient air monitoring 
stations. The EPA Regional Administrator may specify more than two 
monitoring stations if it is found that two stations are 
insufficient to adequately determine if the Pb standard is being 
attained and maintained. The Regional Administrator may also specify 
that stations be located in areas outside the boundaries of the 
urbanized areas.
    Concerning the previously discussed required minimum of two 
stations, at least one of the stations must be a category (a) type 
station and the second may be either category (a) or (b) depending 
upon the extent of the point source's impact and the existence of 
residential neighborhoods surrounding the source. When the source is 
located in an area that is subject to NAMS requirements as in 
Section 3 of this Appendix, it is preferred that the NAMS site be 
used to describe the population's exposure and the second SLAMS site 
be used as a category (a) site. Both of these categories of stations 
are defined in section 3.
    To locate monitoring stations, it will be necessary to obtain 
background information such as point source emissions inventories, 
climatological summaries, and local geographical characteristics. 
Such information should be used to identify areas that are most 
suitable to the particular monitoring objective and spatial scale of 
representativeness desired. References 9 & 10 of this appendix 
provide additional guidance on locating sites to meet specific urban 
area monitoring objectives and should be used in locating new 
stations or evaluating the adequacy of existing stations.
    After locating each Pb station and, to the extent practicable, 
taking into consideration the collective impact of all Pb sources 
and surrounding physical characteristics of the siting area, a 
spatial scale of representativeness must be assigned to each 
station.
* * * * *

3. Network Design for National Air Monitoring Stations (NAMS)

* * * * *
    For each urban area where NAMS are required, both categories of 
monitoring stations must be established. In the case of Pb and 
SO2 if only one NAMS is needed, then category (a) must be 
used. The analysis and interpretation of data from NAMS should 
consider the distinction between these types of stations as 
appropriate.
* * * * *

3.2  Sulfur Dioxide Design Criteria for NAMS

    * * * The actual number and location of the NAMS must be 
determined by EPA Regional Offices and the State Agency, subject to 
the approval of EPA Headquarters, Office of Air Quality Planning and 
Standards (OAQPS).
* * * * *

3.3  Carbon Monoxide (CO) Design Criteria for NAMS

    * * * At the national level, EPA will not routinely require data 
from as many stations as are required for PM-10, and perhaps 
SO2, since CO trend stations are principally needed to 
assess the overall air quality progress resulting from the emission 
controls required by the Federal motor vehicle control program 
(FMVCP) and other local controls.
* * * * *

[[Page 3036]]

    3.6  Lead (Pb) Design Criteria for NAMS. In order to achieve the 
national monitoring objective, one NAMS site must be located in one 
of the two cities with the greatest population in the following ten 
regions of the country (the choice of which of the two metropolitan 
areas should have the lead NAMS requirement is made by the 
Administrator or the Administrator's designee using the 
recommendation of the Regional Administrators or the Regional 
Administrators' designee):

Table 1.--EPA Regions & Two Current Largest MSA/CMSAs (Using 1995 Census
                                  Data)
------------------------------------------------------------------------
            Region (States)                   Two Largest MSA/CMSAs
------------------------------------------------------------------------
I (Connecticut, Massachusetts, Maine,    Boston-Worcester-Lawrence CMSA,
 New Hampshire, Rhode Island, Vermont).   Hartford, CT MSA.
II (New Jersey, New York, Puerto Rico,   New York-Northern New Jersey-
 U.S. Virgin Islands).                    Long Island, CMSA, San Juan-
                                          Caguas-Arecibo, PR CMSA.
III (Delaware, Maryland, Pennsylvania,   Washington-Baltimore CMSA,
 Virginia, West Virginia, Washington,     Philadelphia-Wilmington-
 DC).                                     Atlantic City CMSA.
IV (Alabama, Florida, Georgia,           Miami-Fort Lauderdale CMSA,
 Kentucky, Mississippi, North Carolina,   Atlanta, GA MSA.
 South Carolina, Tennessee).
V (Illinois, Indiana, Michigan,          Chicago-Gary-Kenosha CMSA,
 Minnesota, Ohio, Wisconsin).             Detroit-Ann Arbor-Flint CMSA.
VI (Arkansas, Louisiana, New Mexico,     Dallas-Fort Worth CMSA, Houston-
 Oklahoma, Texas).                        Galveston-Brazoria CMSA.
VII (Iowa, Kansas, Missouri, Nebraska).  St. Louis MSA, Kansas City MSA.
VIII (Colorado, Montana, North Dakota,   Denver-Boulder-Greeley CMSA,
 South Dakota, Utah, Wyoming).            Salt Lake City-Ogden MSA.
IX (American Samoa, Arizona,             Los Angeles-Riverside-Orange
 California, Guam, Hawaii, Nevada).       County CMSA, San Francisco-
                                          Oakland-San Jose CMSA.
X (Alaska, Idaho, Oregon, Washington)..  Seattle-Tacoma-Bremerton CMSA,
                                          Portland-Salem CMSA.
------------------------------------------------------------------------

    In addition, one NAMS site must be located in each of the MSA/
CMSAs where one or more violations of the quarterly Pb NAAQS have 
been recorded over the previous eight quarters. If a violation of 
the quarterly Pb NAAQS is measured at a monitoring site outside of a 
MSA/CMSA, one NAMS site must be located within the county in a 
populated area, apart from the Pb source, to assess area wide Pb air 
pollution levels. These NAMS sites should represent the maximum Pb 
concentrations measured within the MSA/CMSA, city, or county that is 
not directly affected from a single Pb point source. Further, in 
order that on-road mobile source emissions may continue to be 
verified as not contributing to lead NAAQS violations, roadside 
ambient lead monitors should be considered as viable NAMS site 
candidates. A NAMS site may be a microscale or middle scale category 
(a) station, located adjacent to a major roadway (e.g., >30,000 
ADT), or a neighborhood scale category (b) station that is located 
in a highly populated residential section of the MSA/CMSA or county 
where the traffic density is high. Data from these sites will be 
used to assess general conditions for large MSA/CMSAs and other 
populated areas as a marker for national trends, and to confirm 
continued attainment of the Pb NAAQS. In some cases, the MSA/CMSA 
subject to the latter lead NAMS requirement due to a violating point 
source will be the same MSA/CMSA subject to the lead NAMS 
requirement based upon its population. For these situations, the 
total minimum number of required lead NAMS is one.
* * * * *

6. References

* * * * *
    6. Lead Guideline Document, U. S. Environmental Protection 
Agency, Research Triangle Park, NC. EPA-452/R-93-009.
    7. Air Quality Criteria for Lead. Office of Research and 
Development, U.S. Environmental Protection Agency, Washington, DC. 
EPA-600/8-83-028 aF-dF, 1986, and supplements EPA-600/8-89/049F, 
August 1990. (NTIS document numbers PB87-142378 and PB91-138420.)
* * * * *
    10. ``Guidance for Conducting Ambient Air Monitoring for Lead 
Around Point Sources,'' Office of Air Quality Planning and 
Standards, U.S. Environmental Protection Agency, Research Triangle 
Park, NC EPA-454/R-92-009, May 1997.
* * * * *
    19. National Air Pollutant Emissions Trends, 1900-1995, Office 
of Air Quality Planning and Standards, U. S. Environmental 
Protection Agency, Research Triangle Park, NC. EPA-454/R96-007, 
October 1996, updated annually.
    6. Appendix E is amended by revising the first paragraph of section 
7.1, adding a sentence at the beginning of section 7.3, revising 
section 7.4, and revising reference 18 in section 13 to read as 
follows:

Appendix E--Probe and Monitoring Path Siting Criteria for Ambient 
Air Quality Monitoring

* * * * *
    7.1  Vertical Placement. Optimal placement of the sampler inlet 
for Pb monitoring should be at breathing height level. However, 
practical factors such as prevention of vandalism, security, and 
safety precautions must also be considered when siting a Pb monitor. 
Given these considerations, the sampler inlet for microscale Pb 
monitors must be 2-7 meters above ground level. The lower limit was 
based on a compromise between ease of servicing the sampler and the 
desire to avoid unrepresentative conditions due to re-entrainment 
from dusty surfaces. The upper limit represents a compromise between 
the desire to have measurements which are most representative of 
population exposures and a consideration of the practical factors 
noted above.
* * * * *
    7.3. Spacing from Roadways. This criteria applies only to those 
Pb sites designed to assess lead concentrations from mobile sources. 
Numerous studies have shown that ambient Pb levels near mobile 
sources are a function of the traffic volume and are most pronounced 
at ADT >30,000 within the first 15 meters on the downwind side of 
the roadways.
* * * * *
    7.4. Spacing from trees and other considerations. Trees can 
provide surfaces for deposition or adsorption of Pb particles and 
obstruct normal wind flow patterns. For microscale and middle scale 
category (a) sites there must not be any tree(s) between the source 
of the Pb and the sampler. For neighborhood scale category (b) 
sites, the sampler should be at least 20 meters from the drip line 
of trees. The sampler must, however, be placed at least 10 meters 
from the drip line of trees which could be classified as an 
obstruction, i.e., the distance between the tree(s) and the sampler 
is less than the height that the tree protrudes above the sampler.
* * * * *

13. References

* * * * *
    18. Air Quality Criteria for Lead. Office of Research and 
Development, U.S. Environmental Protection Agency, Washington, DC 
EPA-600/8-83-028 aF-dF, 1986, and supplements EPA-600/8-89/049F, 
August 1990. (NTIS document numbers PB87-142378 and PB91-138420.)
* * * * *
    7. Section 1 and section 2 b of Appendix G are revised to read as 
follows:

Appendix G--Uniform Air Quality Index and Daily Reporting

* * * * *
    1. General. This appendix describes the uniform air quality index 
to be used by States in reporting the daily air quality index required 
by Sec. 58.50.

[[Page 3037]]

    2. Definitions.
* * * * *
    b. Reporting Agency means the applicable State agency or a local 
air pollution control agency designated by the State, that will carry 
out the provisions of Sec. 58.50.
* * * * *
[FR Doc. 99-1125 Filed 1-19-99; 8:45 am]
BILLING CODE 6560-50-P