2008...................................  July 1, 2009...................  October 15, 2010. *
2009...................................  July 1, 2010...................  October 15, 2010. *
2010...................................  May 1, 2011 *..................  May 1, 2011. *
----------------------------------------------------------------------------------------------------------------
* Indicates change from generic schedule in 40 CFR 50.14.

 Table 8--Final Schedule for Exceptional Event Flagging and Documentation Submission if Designations Promulgated
                                                Within Two Years

----------------------------------------------------------------------------------------------------------------
     Air quality data collected for                                         Detailed  documentation  submission
             calendar year                   Event flagging deadline                     deadline
----------------------------------------------------------------------------------------------------------------
2006...................................  July 1, 2009 *.................  October 15, 2009.
2007...................................  July 1, 2009 *.................  October 15, 2009. *
2008...................................  July 1, 2009...................  October 15, 2009. *
2009...................................  May 1, 2010 *..................  May 1, 2010. *
----------------------------------------------------------------------------------------------------------------
* Indicates change from generic schedule in 40 CFR 50.14.

VII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

    Under section 3(f)(1) of Executive Order (EO) 12866 (58 FR 51735,
October 4, 1993), this action is an ``economically significant
regulatory action'' because it is likely to have an annual effect on
the economy of $100 million or more. Accordingly, EPA submitted this
action to the Office of Management and Budget (OMB) for review under EO
12866 and any changes made in response to OMB recommendations have been
documented in the docket for this action (EPA-HQ-OAR-2006-0735). In
addition, EPA prepared a Regulatory Impact Analysis (RIA) of the
potential costs and benefits associated with this action. A copy of the
analysis is available in the RIA docket (EPA-HQ-OAR-2008-0253) and the
analysis is briefly summarized here. The RIA estimates the costs and
monetized human health and welfare benefits of attaining four
alternative Pb NAAQS nationwide. Specifically, the RIA examines the
alternatives of 0.50 [mu]g/m3, 0.40 [mu]g/m3,
0.30 [mu]g/m3, 0.20 [mu]g/m3, 0.15 [mu]g/
m3 and 0.10 [mu]g/m3. The RIA contains
illustrative analyses that consider a limited number of emissions
control scenarios that States and Regional Planning Organizations might
implement to achieve these alternative Pb NAAQS. However, the CAA and
judicial decisions make clear that the economic and technical
feasibility of attaining ambient standards are not to be considered in
setting or revising

NAAQS, although such factors may be considered in the development of
State plans to implement the standards. Accordingly, although an RIA
has been prepared, the results of the RIA have not been considered in
issuing this final rule.

B. Paperwork Reduction Act

    The information collection requirements in this final rule will be
submitted for approval to the Office of Management and Budget (OMB)
under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. The
information collection requirements are not enforceable until OMB
approves them.
    The information collected under 40 CFR part 53 (e.g., test results,
monitoring records, instruction manual, and other associated
information) is needed to determine whether a candidate method intended
for use in determining attainment of the National Ambient Air Quality
Standards (NAAQS) in 40 CFR part 50 will meet the design, performance,
and/or comparability requirements for designation as a Federal
reference method (FRM) or Federal equivalent method (FEM). While this
final rule amends the requirements for Pb FRM and FEM determinations,
they merely provide additional flexibility in meeting the FRM/FEM
determination requirements. Furthermore, we do not expect the number of
FRM or FEM determinations to increase over the number that is currently
used to estimate burden associated with Pb FRM/FEM determinations
provided in the current ICR for 40 CFR part 53 (EPA ICR numbers
0559.12). As such, no change in the burden estimate for 40 CFR part 53
has been made as part of this rulemaking.
    The information collected and reported under 40 CFR part 58 is
needed to determine compliance with the NAAQS, to characterize air
quality and associated health and ecosystem impacts, to develop
emissions control strategies, and to measure progress for the air
pollution program. The proposed amendments would revise the technical
requirements for Pb monitoring sites, require the siting and operation
of additional Pb ambient air monitors, and the reporting of the
collected ambient Pb monitoring data to EPA's Air Quality System (AQS).
We have estimated the burden based on the final monitoring requirements
of this rule. Based on these requirements, the annual average reporting
burden for the collection under 40 CFR part 58 (averaged over the first
3 years of this ICR) for 150 respondents is estimated to increase by a
total of 22,376 labor hours per year with an increase of $1,910,059 per
year. Burden is defined at 5 CFR 1320.3(b).
    An agency may not conduct or sponsor, and a person is not required
to respond to, a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for EPA's
regulations in 40 CFR are listed in 40 CFR part 9. When this ICR is
approved by OMB, the Agency will publish a technical amendment to 40
CFR part 9 in the Federal Register to display the OMB control number
for the approved information collection requirements contained in this
final rule.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute 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 organizations, and small governmental jurisdictions.
    For purposes of assessing the impacts of this rule on small
entities, small entity is defined as: (1) A small business that is a
small industrial entity as defined by the Small Business
Administration's (SBA) regulations at 13 CFR 121.201; (2) a small
governmental jurisdiction that is a government of a city, county, town,
school district or special district with a population of less than
50,000; and (3) a small organization that is any not-for-profit
enterprise which is independently owned and operated and is not
dominant in its field.
    After considering the economic impacts of this final rule on small
entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities. This final
rule will not impose any requirements on small entities. Rather, this
rule establishes national standards for allowable concentrations of Pb
in ambient air as required by section 109 of the CAA. American Trucking
Ass'ns v. EPA, 175 F. 3d 1027, 1044-45 (D.C. cir. 1999) (NAAQS do not
have significant impacts upon small entities because NAAQS themselves
impose no regulations upon small entities). Similarly, the amendments
to 40 CFR part 58 address the requirements for States to collect
information and report compliance with the NAAQS and will not impose
any requirements on small entities.

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and tribal
governments and the private sector. Unless otherwise prohibited by law,
under section 202 of the UMRA, EPA generally must prepare a written
statement, including a cost-benefit analysis, for proposed and final
rules with ``Federal mandates'' that may result in expenditures to
State, local, and tribal governments, in the aggregate, or to the
private sector, of $100 million or more in any one year. Before
promulgating an EPA rule for which a written statement is required
under section 202, section 205 of the UMRA generally requires EPA to
identify and consider a reasonable number of regulatory alternatives
and to adopt the least costly, most cost-effective or least burdensome
alternative that achieves the objectives of the rule. The provisions of
section 205 do not apply when they are inconsistent with applicable
law. Moreover, section 205 allows EPA to adopt an alternative other
than the least costly, most cost-effective or least burdensome
alternative if the Administrator publishes with the final rule an
explanation why that alternative was not adopted. Before EPA
establishes any regulatory requirements that may significantly or
uniquely affect small governments, including tribal governments, it
must have developed under section 203 of the UMRA a small government
agency plan. The plan must provide for notifying potentially affected
small governments, enabling officials of affected small governments to
have meaningful and timely input in the development of EPA regulatory
proposals with significant Federal intergovernmental mandates, and
informing, educating, and advising small governments on compliance with
the regulatory requirements.
    This action is not subject to the requirements of sections 202 and
205 of the UMRA. EPA has determined that this final rule does not
contain a Federal mandate that may result in expenditures of $100
million or more for State, local, and tribal governments, in the
aggregate, or the private sector in any one year. The revisions to the
Pb NAAQS impose no enforceable duty on any State, local or tribal
governments or the private sector. The expected costs associated with
the increased monitoring requirements are described in EPA's ICR
document, but those costs are not expected to exceed $100 million in
the aggregate for any year. Furthermore, as

indicated previously, in setting a NAAQS EPA cannot consider the
economic or technological feasibility of attaining ambient air quality
standards. Because the Clean Air Act prohibits EPA from considering the
types of estimates and assessments described in section 202 when
setting the NAAQS, the UMRA does not require EPA to prepare a written
statement under section 202 for the revisions to the Pb NAAQS.
    With regard to implementation guidance, the CAA imposes the
obligation for States to submit SIPs to implement the Pb NAAQS. In this
final rule, EPA is merely providing an interpretation of those
requirements. However, even if this rule did establish an independent
obligation for States to submit SIPs, it is questionable whether an
obligation to submit a SIP revision would constitute a Federal mandate
in any case. The obligation for a State to submit a SIP that arises out
of section 110 and section 191 of the CAA is not legally enforceable by
a court of law, and at most is a condition for continued receipt of
highway funds. Therefore, it is possible to view an action requiring
such a submittal as not creating any enforceable duty within the
meaning of 2 U.S.C. 658 for purposes of the UMRA. Even if it did, the
duty could be viewed as falling within the exception for a condition of
Federal assistance under 2 U.S.C. 658.
    EPA has determined that this final rule contains no regulatory
requirements that might significantly or uniquely affect small
governments because it imposes no enforceable duty on any small
governments. Therefore, this rule is not subject to the requirements of
section 203 of the UMRA.

E. Executive Order 13132: Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August
10, 1999), requires EPA to develop an accountable process to ensure
``meaningful and timely input by State and local officials in the
development of regulatory policies that have federalism implications.''
``Policies that have federalism implications'' is defined in the
Executive Order to include regulations that have ``substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government.''
    This final rule does not have federalism implications. It will not
have substantial direct effects on the States, on the relationship
between the national government and the States, or on the distribution
of power and responsibilities among the various levels of government,
as specified in Executive Order 13132. The rule does not alter the
relationship between the Federal government and the States regarding
the establishment and implementation of air quality improvement
programs as codified in the CAA. Under section 109 of the CAA, EPA is
mandated to establish NAAQS; however, CAA section 116 preserves the
rights of States to establish more stringent requirements if deemed
necessary by a State. Furthermore, under CAA section 107, the States
have primary responsibility for implementation of the NAAQS. Finally,
as noted in section E (above) on UMRA, this rule does not impose
significant costs on State, local, or tribal governments or the private
sector. Thus, Executive Order 13132 does not apply to this rule.

F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

    This action does not have tribal implications, as specified in
Executive Order 13175 (65 FR 67249, November 9, 2000). It does not have
a substantial direct effect on one or more Indian Tribes, since Tribes
are not obligated to adopt or implement any NAAQS or monitoring
requirements for NAAQS. Thus, Executive Order 13175 does not apply to
this action.
    Although Executive Order 13175 does not apply to this action, EPA
contacted tribal environmental professionals during the development of
this rule. EPA staff participated in the regularly scheduled Tribal Air
Call sponsored by the National Tribal Air Association during the spring
of 2008 as the proposal was under development, and also offered several
informational briefings on the proposal to Tribal environmental
professionals in Summer 2008 during the public comment period on the
proposed rule. EPA sent individual letters to all federally recognized
Tribes within the lower 48 states and Alaska to give Tribal leaders the
opportunity for consultation, and EPA staff also participated in Tribal
public meetings, such as the National Tribal Forum meeting in June
2008, where Tribes discussed their concerns regarding the proposed
rule. EPA received comments from a number of Tribes on the proposed
rule; these comments are addressed in the relevant sections of the
preamble and Response to Comments for this rulemaking.

G. Executive Order 13045: Protection of Children from Environmental
Health & Safety Risks

    This action is subject to EO 13045 (62 FR 19885, April 23, 1997)
because it is an economically significant regulatory action as defined
by EO 12866, and we believe that the environmental health risk
addressed by this action has a disproportionate effect on children. The
final rule establishes uniform national ambient air quality standards
for Pb; these standards are designed to protect public health with an
adequate margin of safety, as required by CAA section 109. However, the
protection offered by these standards may be especially important for
children because neurological effects in children are among if not the
most sensitive health endpoints for Pb exposure. Because children are
considered a sensitive population, we have carefully evaluated the
environmental health effects of exposure to Pb pollution among
children. These effects and the size of the population affected are
summarized in chapters 6 and 8 of the Criteria Document and sections
3.3 and 3.4 of the Staff Paper, and the results of our evaluation of
the effects of Pb pollution on children are discussed in sections II.B
and II.C of the notice of proposed rulemaking, and section II.A of this
preamble.

H. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution or Use

    This rule is not a ``significant energy action'' as defined in
Executive Order 13211, ``Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR 28355
(May 22, 2001)) because it is not likely to have a significant adverse
effect on the supply, distribution, or use of energy. The purpose of
this rule is to establish revised NAAQS for Pb. The rule does not
prescribe specific control strategies by which these ambient standards
will be met. Such strategies will be developed by States on a case-by-
case basis, and EPA cannot predict whether the control options selected
by States will include regulations on energy suppliers, distributors,
or users. Thus, EPA concludes that this rule is not likely to have any
adverse energy effects.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law No. 104-113, Sec.  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 final rule involves technical standards. EPA has established
low-volume PM10 samplers coupled with XRF analysis as the
FRM for Pb-PM10 measurement. While EPA identified the ISO
standard ``Determination of the particulate lead content of aerosols
collected on filters'' (ISO 9855: 1993) as being potentially
applicable, the final rule does not permit its use. EPA determined that
the use of this voluntary consensus standard would be impractical
because the analysis method does not provide for the method detection
limits necessary to adequately characterize ambient Pb concentrations
for the purpose of determining compliance with the revisions to the Pb
NAAQS.

J. Executive Order 12898: Federal Actions to Address Environmental
Justice in Minority Populations and Low-Income Populations

    Executive Order 12898 (59 FR 7629; Feb. 16, 1994) establishes
federal executive policy on environmental justice. Its main provision
directs federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing, as appropriate, disproportionately high
and adverse human health or environmental effects of their programs,
policies, and activities on minority populations and low-income
populations in the United States.
    EPA has determined that this final rule will not have
disproportionately high and adverse human health or environmental
effects on minority or low-income populations because it increases the
level of environmental protection for all affected populations without
having any disproportionately high and adverse human health or
environmental effects on any population, including any minority or low-
income population. The final rule establishes uniform national
standards for Pb in ambient air. In the Administrator's judgment, the
revised Pb NAAQS protect public health, including the health of
sensitive groups, with an adequate margin of safety. As discussed
earlier in this preamble (see section II) and in the Response to
Comments, the Administrator expressly considered the available
information regarding health effects among vulnerable and susceptible
populations in making the determination about which standards are
requisite.
    Some commenters expressed concerns that EPA had failed to
adequately assess the environmental justice implications of its
proposed decision. These commenters asserted specifically that low-
income and minority populations constitute susceptible subpopulations
and that the proposed revisions to the primary Pb standards would be
insufficient to protect these subpopulations with an adequate margin of
safety. In addition, some commenters stated that EPA had failed to
adequately evaluate or address the disproportionate adverse impact of
Pb exposure on poor and minority populations as required by EO 12898.
These commenters assert that in spite of significant scientific
evidence indicating that the burden of lead exposure is higher in poor
communities and communities of color, EPA has not taken the differing
impacts of lead exposure into account in revising the Pb NAAQS.
    At the time of proposal, EPA prepared a technical memo to assess
the socio-demographic characteristics of populations living near
ambient air Pb monitors and stationary sources of Pb emissions (Pekar
et al., 2008). Due to limitations in the available data, most
significantly limitations on information regarding whether current
ambient air concentrations of Pb (as measured by fixed-site monitors or
proximity to stationary sources of Pb) are associated with elevated
exposure or increased risk for any socio-demographic group, EPA was not
able to draw conclusions regarding the impact of Pb air pollution on
minority and low-income populations in this analysis [or ``memo''].
However, EPA believes that the newly strengthened Pb standards and the
new requirements for ambient air monitoring for Pb will have the
greatest benefit in reducing health risks associated with exposure to
ambient air Pb in those areas where ambient air concentrations are
currently the highest. Thus, to the extent that any population groups,
including minorities or low-income populations, are currently
experiencing disproportionate exposure to ambient air-related Pb, those
groups can be expected to experience relatively greater air quality
improvements under the revised standards. Nationwide, these revised,
more stringent standards will not have adverse health impacts on any
population, including any minority or low-income population.

K. Congressional Review Act

    The Congressional Review Act, 5 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 submitted 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. A major rule cannot
take effect until 60 days after it is published in the Federal
Register. This action is a ``major rule'' as defined by 5 U.S.C.
804(2). This rule will be effective January 12, 2009.

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List of Subjects

40 CFR Part 50

    Environmental protection, Air pollution control, Carbon monoxide,
Lead, Nitrogen dioxide, Ozone, Particulate matter, Sulfur oxides.

40 CFR Part 51

    Environmental protection, Administrative practice and procedure,
Air pollution control, Carbon monoxide, Intergovernmental relations,
Lead, Nitrogen dioxide, Ozone, Particulate matter, Reporting and
recordkeeping requirements.

40 CFR Part 53

    Environmental protection, Administrative practice and procedure,
Air pollution control, Intergovernmental relations, Reporting and
recordkeeping requirements.

40 CFR Part 58

    Environmental protection, Administrative practice and procedure,
Air pollution control, Intergovernmental relations, Reporting and
recordkeeping requirements.

    Dated: October 15, 2008.
Stephen L. Johnson,
Administrator.

0
For the reasons stated in the preamble, title 40, chapter I of the code
of Federal regulations is amended as follows:

PART 50--NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY
STANDARDS

0
1. The authority citation for part 50 continues to read as follows:

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

0
2. Section 50.3 is revised to read as follows:

Sec.  50.3  Reference conditions.

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

0
3. Section 50.12 is amended by designating the existing text as
paragraph (a) and adding paragraph (b) to read as follows:

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

* * * * *
    (b) The standards set forth in this section will remain applicable
to all areas notwithstanding the promulgation of lead national ambient
air quality standards (NAAQS) in Sec.  50.16. The lead NAAQS set forth
in this section will no longer apply to an area one year after the
effective date of the designation of that area, pursuant to section 107
of the Clean Air Act, for the lead NAAQS set forth in Sec.  50.16;
except that for areas designated nonattainment for the lead NAAQS set
forth in this section as of the effective date of Sec.  50.16, the lead
NAAQS set forth in this section will apply until that area submits,
pursuant to section 191 of the Clean Air Act, and EPA approves, an
implementation plan providing for attainment and/or maintenance of the
lead NAAQS set forth in Sec.  50.16.

0
4. Section 50.14 is amended by:
0
a. Revising paragraph (a)(2);
0
b. Revising paragraph (c)(2)(iii);
0
c. Redesignating paragraph (c)(2)(v) as paragraph (c)(2)(vi) and adding
a new paragraph (c)(2)(v); and
0
d. Redesignating existing paragraphs (c)(3)(iii) and (c)(3)(iv) as
paragraphs (c)(3)(iv) and (c)(3)(v), respectively, and adding a new
paragraph (c)(3)(iii).
    The additions and revisions read as follows:

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

    (a) * * *
    (2) Demonstration to justify data exclusion may include any
reliable and accurate data, but must demonstrate a clear causal
relationship between the measured exceedance or violation of such
standard and the event in accordance with paragraph (c)(3)(iv) of this
section.
* * * * *
    (c) * * *
    (2) * * *
    (iii) Flags placed on data as being due to an exceptional event
together with an initial description of the event shall be submitted to
EPA not later than July 1st of the calendar year following the year in
which the flagged measurement occurred, except as allowed under
paragraph (c)(2)(iv) or (c)(2)(v) of this section.
* * * * *
    (v) For lead (Pb) data collected during calendar years 2006-2008,
that the State identifies as resulting from an exceptional event, the
State must notify EPA of the flag and submit an initial description of
the event no later than July 1, 2009. For Pb data collected during
calendar year 2009, that the State identifies as resulting from an
exceptional event, the State must notify EPA of the flag and submit an
initial description of the event no later than July 1, 2010. For Pb
data collected during calendar year 2010, that the State identifies as
resulting from an exceptional event, the State must notify EPA of the
flag and submit an initial description of the event no later than May
1, 2011.
* * * * *
    (3) * * *
    (iii) A State that flags Pb data collected during calendar years
2006-2009, pursuant to paragraph (c)(2)(v) of this section shall, after
notice and opportunity for public comment, submit to EPA a
demonstration to justify exclusion of the data not later than October
15, 2010. A State that flags Pb data collected during calendar year
2010 shall, after notice and opportunity for public comment, submit to
EPA a demonstration to justify the exclusion of the data not later than
May 1, 2011. A state must submit the public comments it received along
with its demonstration to EPA.
* * * * *

0
5. Section 50.16 is added to read as follows:

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

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

0
6. Appendix G is amended as follows:
0
a. In section 10.2 the definition of the term ``VSTP'' in
the equation is revised,
0
b. In section 14 reference 10 is added and reference 15 is revised:

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

* * * * *
    10.2 * * *
    VSTP = Air volume from section 10.1.
* * * * *
    14. * * *
    10. Intersociety Committee (1972). Methods of Air Sampling and
Analysis. 1015 Eighteenth Street, N.W. Washington, D.C.: American
Public Health Association. 365-372. * * *
    15. Sharon J. Long, et al., ``Lead Analysis of Ambient Air
Particulates: Interlaboratory Evaluation of EPA Lead Reference
Method'' APCA Journal, 29, 28-31 (1979).
* * * * *

0
7. Appendix Q is added to read as follows:

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

    This Federal Reference Method (FRM) draws heavily from the
specific analytical protocols used by the U.S. EPA.
    1. Applicability and Principle
    1.1 This method provides for the measurement of the lead (Pb)
concentration in particulate matter that is 10 micrometers or less
(PM10) in ambient air. PM10 is collected on an
acceptable (see section 6.1.2) 46.2 mm diameter
polytetrafluoroethylene (PTFE) filter for 24 hours using active
sampling at local conditions with a low-volume air sampler. The low-
volume sampler has an average flow rate of 16.7 liters per minute
(Lpm) and total sampled volume of 24 cubic meters (m3) of
air. The analysis of Pb in PM10 is performed on each
individual 24-hour sample. Gravimetric mass analysis of
PM10c filters is not required for Pb analysis. For the
purpose of this method, PM10 is defined as particulate
matter having an aerodynamic diameter in the nominal range of 10
micrometers (10 [mu]m) or less.
    1.2 For this reference method, PM10 shall be
collected with the PM10c federal reference method (FRM)
sampler as described in Appendix O to Part 50 using the same sample
period, measurement procedures, and requirements specified in
Appendix L of Part 50. The PM10c sampler is also being
used for measurement of PM10-2.5 mass by difference and
as such, the PM10c sampler must also meet all of the
performance requirements specified for PM2.5 in Appendix
L. The concentration of Pb in the atmosphere is determined in the
total volume of air sampled and expressed in micrograms per cubic
meter ([mu]g/m3) at local temperature and pressure
conditions.
    1.3 The FRM will serve as the basis for approving Federal
Equivalent Methods (FEMs) as specified in 40 CFR Part 53 (Reference
and Equivalent Methods). This FRM specifically applies to the
analysis of Pb in PM10 filters collected with the
PM10c sampler. If these filters are analyzed for elements
other than Pb, then refer to the guidance provided in the EPA
Inorganic Compendium Method IO-3.3 (Reference 1 of section 8) for
multi-element analysis.
    1.4 The PM10c air sampler draws ambient air at a
constant volumetric flow rate into a specially shaped inlet and
through an inertial particle size separator, where the suspended
particulate matter in the PM10 size range is separated
for collection on a PTFE filter over the specified sampling period.
The Pb content of the PM10 sample is analyzed by energy-
dispersive X-ray fluorescence spectrometry (EDXRF). Energy-
dispersive X-ray fluorescence spectrometry provides a means for
identification of an element by measurement of its characteristic X-
ray emission energy. The method allows for quantification of the
element by measuring the intensity of X-rays emitted at the
characteristic photon energy and then relating this intensity to the
elemental concentration. The number or intensity of X-rays produced
at a given energy provides a measure of the amount of the element
present by comparisons with calibration standards. The X-rays are
detected and the spectral signals are acquired and processed with a
personal computer. EDXRF is commonly used as a non-destructive
method for quantifying trace elements in PM. A detailed explanation
of quantitative X-ray spectrometry is described in references 2, 3
and 4.
    1.5 Quality assurance (QA) procedures for the collection of
monitoring data are contained in Part 58, Appendix A.
    2. PM10 Pb Measurement Range and Detection Limit. The values
given below in section 2.1 and 2.2 are typical of the method
capabilities. Absolute values will vary for individual situations
depending on the instrument, detector age, and operating conditions
used. Data are typically reported in ng/m3 for ambient
air samples; however, for this reference method, data will be
reported in [mu]g/m3 at local temperature and pressure
conditions.
    2.1 EDXRF Pb Measurement Range. The typical ambient air
measurement range is 0.001 to 30 [mu]g Pb/m3, assuming an
upper range calibration standard of about 60 [mu]g Pb per square
centimeter (cm2), a filter deposit area of 11.86
cm2, and an air volume of 24 m3. The top range
of the EDXRF instrument is much greater than what is stated here.
The top measurement range of quantification is defined by the level
of the high concentration calibration standard used and can be
increased to expand the measurement range as needed.
    2.2 Detection Limit (DL). A typical estimate of the one-sigma
detection limit (DL) is about 2 ng Pb/cm2 or 0.001 [mu]g
Pb/m3, assuming a filter size of 46.2 mm (filter deposit
area of 11.86 cm2) and a sample air volume of 24
m3. The DL is an estimate of the lowest amount of Pb that
can be reliably distinguished from a blank filter. The one-sigma
detection limit for Pb is calculated as the average overall
uncertainty or propagated error for Pb, determined from measurements
on a series of blank filters from the filter lot(s) in use.
Detection limits must be determined for each filter lot in use. If a
new filter lot is used, then a new DL must be determined. The
sources of random error which are considered are calibration
uncertainty; system stability; peak and background counting
statistics; uncertainty in attenuation corrections; and uncertainty
in peak overlap corrections, but the dominating source by far is
peak and background counting statistics. At a minimum, laboratories
are to determine annual estimates of the DL using the guidance
provided in Reference 5.
    3. Factors Affecting Bias and Precision of Lead Determination by
EDXRF
    3.1 Filter Deposit. X-ray spectra are subject to distortion if
unusually heavy deposits are analyzed. This is the result of
internal absorption of both primary and secondary X-rays within the
sample; however, this is not an issue for Pb due to the energetic X-
rays used to fluoresce Pb and the energetic characteristic X-rays
emitted by Pb. The optimum mass filter loading for multi-elemental
EDXRF analyis is about 100 [mu]g/cm2 or 1.2 mg/filter for
a 46.2-mm filter. Too little deposit material can also be
problematic due to low counting statistics and signal noise. The
particle mass deposit should minimally be 15 [mu]g/cm2.
The maximum PM10 filter loading or upper concentration
limit of mass expected to be collected by the PM10c
sampler is 200 [mu]g/m3 (Appendix O to Part 50, Section
3.2). This equates to a mass loading of about 400 [mu]g/
cm2 and is the maximum expected loading for
PM10c filters. This maximum loading is acceptable for the
analysis of Pb and other high-Z elements with very energetic
characteristic X-rays. A properly collected sample will have a
uniform deposit over the entire collection area. Samples with
physical deformities (including a visually non-

uniform deposit area) should not be quantitatively analyzed. Tests
on the uniformity of particle deposition on PM10C filters
showed that the non-uniformity of the filter deposit represents a
small fraction of the overall uncertainty in ambient Pb
concentration measurement. The analysis beam of the XRF analyzer
does not cover the entire filter collection area. The minimum
allowable beam size is 10 mm.
    3.2 Spectral Interferences and Spectral Overlap. Spectral
interference occurs when the entirety of the analyte spectral lines
of two species are nearly 100% overlapped. The presence of arsenic
(As) is a problematic interference for EDXRF systems which use the
Pb L[alpha] line exclusively to quantify the Pb concentration. This
is because the Pb L[alpha] line and the As K[alpha] lines severely
overlap. The use of multiple Pb lines, including the L[beta] and/or
the L[gamma] lines for quantification must be used to reduce the
uncertainty in the Pb determination in the presence of As. There can
be instances when lines partially overlap the Pb spectral lines, but
with the energy resolution of most detectors these overlaps are
typically de-convoluted using standard spectral de-convolution
software provided by the instrument vendor. An EDXRF protocol for Pb
must define which Pb lines are used for quantification and where
spectral overlaps occur. A de-convolution protocol must be used to
separate all the lines which overlap with Pb.
    3.3 Particle Size Effects and Attenuation Correction Factors. X-
ray attenuation is dependent on the X-ray energy, mass sample
loading, composition, and particle size. In some cases, the
excitation and fluorescent X-rays are attenuated as they pass
through the sample. In order to relate the measured intensity of the
X-rays to the thin-film calibration standards used, the magnitude of
any attenuation present must be corrected for. See references 6, 7,
and 8 for more discussion on this issue. Essentially no attenuation
corrections are necessary for Pb in PM10: Both the
incoming excitation X-rays used for analyzing lead and the
fluoresced Pb X-rays are sufficiently energetic that for particles
in this size range and for normal filter loadings, the Pb X-ray
yield is not significantly impacted by attenuation.
    4. Precision
    4.1 Measurement system precision is assessed according to the
procedures set forth in Appendix A to part 58. Measurement method
precision is assessed from collocated sampling and analysis. The
goal for acceptable measurement uncertainty, as precision, is
defined as an upper 90 percent confidence limit for the coefficient
of variation (CV) of 20 percent.
    5. Bias
    5.1 Measurement system bias for monitoring data is assessed
according to the procedures set forth in Appendix A of part 58. The
bias is assessed through an audit using spiked filters. The goal for
measurement bias is defined as an upper 95 percent confidence limit
for the absolute bias of 15 percent.
    6. Measurement of PTFE Filters by EDXRF
    6.1 Sampling
    6.1.1 Low-Volume PM10c Sampler. The low-volume PM10c
sampler shall be used for PM10 sample collection and
operated in accordance with the performance specifications described
in Part 50, Appendix L.
    6.1.2 PTFE Filters and Filter Acceptance Testing. The PTFE
filters used for PM10c sample collection shall meet the
specifications provided in Part 50, Appendix L. The following
requirements are similar to those currently specified for the
acceptance of PM2.5 filters that are tested for trace
elements by EDXRF. For large filter lots (greater than 500 filters)
randomly select 20 filters from a given lot. For small lots (less
than 500 filters) a lesser number of filters may be taken. Analyze
each blank filter separately and calculate the average lead
concentration in ng/cm2. Ninety percent, or 18 of the 20
filters, must have an average lead concentration that is less than
4.8 ng Pb/cm2.
    <IP_ADDRESS> Filter Blanks. Field blank filters shall be collected
along with routine samples. Field blank filters will be collected
that are transported to the sampling site and placed in the sampler
for the duration of sampling without sampling. Laboratory blank
filters from each filter lot used shall be analyzed with each batch
of routine sample filters analyzed. Laboratory blank filters are
used in background subtraction as discussed below in Section 6.2.4.
    6.2 Analysis. The four main categories of random and systematic
error encountered in X-ray fluorescence analysis include errors from
sample collection, the X-ray source, the counting process, and
inter-element effects. These errors are addressed through the
calibration process and mathematical corrections in the instrument
software. Spectral processing methods are well established and most
commercial analyzers have software that can implement the most
common approaches (references 9-11) to background subtraction, peak
overlap correction, counting and deadtime corrections.
    6.2.1 EDXRF Analysis Instrument. An energy-dispersive XRF system
is used. Energy-dispersive XRF systems are available from a number
of commercial vendors. Examples include Thermo (www.thermo.com),
Spectro (http://www.spectro.com), Xenemetrix (http://
www.xenemetrix.com) and PANalytical (http://www.panalytical.com).\1\
The analysis is performed at room temperature in either vacuum or in
a helium atmosphere. The specific details of the corrections and
calibration algorithms are typically included in commercial
analytical instrument software routines for automated spectral
acquisition and processing and vary by manufacturer. It is important
for the analyst to understand the correction procedures and
algorithms of the particular system used, to ensure that the
necessary corrections are applied.
---------------------------------------------------------------------------

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

    6.2.2 Thin film standards. Thin film standards are used for
calibration because they most closely resemble the layer of
particles on a filter. Thin films standards are typically deposited
on Nuclepore substrates. The preparation of thin film standards is
discussed in reference 8, and 10. The NIST SRM 2783 (Air Particulate
on Filter Media) is currently available on polycarbonate filters and
contains a certified concentration for Pb. Thin film standards at 15
and 50 [mu]g/cm2 are commercially available from
MicroMatter Inc. (Arlington, WA).
    6.2.3 Filter Preparation. Filters used for sample collection are
46.2-mm PTFE filters with a pore size of 2 microns and filter
deposit area 11.86 cm2. Cold storage is not a requirement
for filters analyzed for Pb; however, if filters scheduled for XRF
analysis were stored cold, they must be allowed to reach room
temperature prior to analysis. All filter samples received for
analysis are checked for any holes, tears, or a non-uniform deposit
which would prevent quantitative analysis. Samples with physical
deformities are not quantitatively analyzable. The filters are
carefully removed with tweezers from the Petri dish and securely
placed into the instrument-specific sampler holder for analysis.
Care must be taken to protect filters from contamination prior to
analysis. Filters must be kept covered when not being analyzed. No
other preparation of filter samples is required.
    6.2.4 Calibration. In general, calibration determines each
element's sensitivity, i.e., its response in x-ray counts/sec to
each [mu]g/cm2 of a standard and an interference
coefficient for each element that causes interference with another
one (See section 3.2 above). The sensitivity can be determined by a
linear plot of count rate versus concentration ([mu]g/
cm2) in which the slope is the instrument's sensitivity
for that element. A more precise way, which requires fewer
standards, is to fit sensitivity versus atomic number. Calibration
is a complex task in the operation of an XRF system. Two major
functions accomplished by calibration are the production of
reference spectra which are used for fitting and the determination
of the elemental sensitivities. Included in the reference spectra
(referred to as ``shapes'') are background-subtracted peak shapes of
the elements to be analyzed (as well as interfering elements) and
spectral backgrounds. Pure element thin film standards are used for
the element peak shapes and clean filter blanks from the same lot as
routine filter samples are used for the background. The analysis of
Pb in PM filter deposits is based on the assumption that the
thickness of the deposit is small with respect to the characteristic
Pb X-ray transmission thickness. Therefore, the concentration of Pb
in a sample is determined by first calibrating the spectrometer with
thin film standards to determine the sensitivity factor for Pb and
then analyzing the unknown samples under identical excitation
conditions as used to determine the calibration. Calibration shall
be performed annually or when significant repairs or changes occur
(e.g., a change in fluorescers, X-ray tubes, or detector).
Calibration establishes the elemental sensitivity factors and the
magnitude of interference or overlap coefficients. See reference 7
for more detailed discussion of calibration and analysis of shapes
standards for background correction, coarse particle absorption
corrections, and spectral overlap.
    <IP_ADDRESS> Spectral Peak Fitting. The EPA uses a library of pure
element peak shapes

(shape standards) to extract the elemental background-free peak
areas from an unknown spectrum. It is also possible to fit spectra
using peak stripping or analytically defined functions such as
modified Gaussian functions. The EPA shape standards are generated
from pure, mono-elemental thin film standards. The shape standards
are acquired for sufficiently long times to provide a large number
of counts in the peaks of interest. It is not necessary for the
concentration of the standard to be known. A slight contaminant in
the region of interest in a shape standard can have a significant
and serious effect on the ability of the least squares fitting
algorithm to fit the shapes to the unknown spectrum. It is these
elemental peak shapes that are fitted to the peaks in an unknown
sample during spectral processing by the analyzer. In addition to
this library of elemental shapes there is also a background shape
spectrum for the filter type used as discussed below in section
<IP_ADDRESS> of this section.
    <IP_ADDRESS> Background Measurement and Correction. A background
spectrum generated by the filter itself must be subtracted from the
X-ray spectrum prior to extracting peak areas. Background spectra
must be obtained for each filter lot used for sample collection. The
background shape standards which are used for background fitting are
created at the time of calibration. If a new lot of filters is used,
new background spectra must be obtained. A minimum of 20 clean blank
filters from each filter lot are kept in a sealed container and are
used exclusively for background measurement and correction. The
spectra acquired on individual blank filters are added together to
produce a single spectrum for each of the secondary targets or
fluorescers used in the analysis of lead. Individual blank filter
spectra which show atypical contamination are excluded from the
summed spectra. The summed spectra are fitted to the appropriate
background during spectral processing. Background correction is
automatically included during spectral processing of each sample.
    7. Calculation.
    7.1 PM10 Pb concentrations. The PM10 Pb concentration
in the atmosphere ([mu]g/m3) is calculated using the
following equation:
[GRAPHIC] [TIFF OMITTED] TR12NO08.000

Where,

MPb is the mass per unit volume for lead in [mu]g/m3;
CPb is the mass per unit area for lead in [mu]g/cm2 as
measured by XRF;
A is the filter deposit area in cm2;
VLC is the total volume of air sampled by the PM10c
sampler in actual volume units measured at local conditions of
temperature and pressure, as provided by the sampler in
m3.

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

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

Where,

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

    8. References
    1. Inorganic Compendium Method IO-3.3; Determination of Metals
in Ambient Particulate Matter Using X-Ray Fluorescence (XRF)
Spectroscopy; U.S. Environmental Protection Agency, Cincinnati, OH
45268. EPA/625/R-96/010a. June 1999.
    2. Jenkins, R., Gould, R.W., and Gedcke, D. Quantitative X-ray
Spectrometry: Second Edition. Marcel Dekker, Inc., New York, NY.
1995.
    3. Jenkins, R. X-Ray Fluorescence Spectrometry: Second Edition
in Chemical Analysis, a Series of Monographs on Analytical Chemistry
and Its Applications, Volume 152. Editor J.D.Winefordner; John Wiley
& Sons, Inc., New York, NY. 1999.
    4. Dzubay, T.G. X-ray Fluorescence Analysis of Environmental
Samples, Ann Arbor Science Publishers Inc., 1977.
    5. Code of Federal Regulations (CFR) 40, Part 136, Appendix B;
Definition and Procedure for the Determination of the Method
Detection Limit--Revision 1.1.
    6. Drane, E.A, Rickel, D.G., and Courtney, W.J., ``Computer Code
for Analysis X-Ray Fluorescence Spectra of Airborne Particulate
Matter,'' in Advances in X-Ray Analysis, J.R. Rhodes, Ed., Plenum
Publishing Corporation, New York, NY, p. 23 (1980).
    7. Analysis of Energy-Dispersive X-ray Spectra of Ambient
Aerosols with Shapes Optimization, Guidance Document; TR-WDE-06-02;
prepared under contract EP-D-05-065 for the U.S. Environmental
Protection Agency, National Exposure Research Laboratory. March
2006.
    8. Billiet, J., Dams, R., and Hoste, J. (1980) Multielement Thin
Film Standards for XRF Analysis, X-Ray Spectrometry, 9(4): 206-211.
    9. Bonner, N.A.; Bazan, F.; and Camp, D.C. (1973). Elemental
analysis of air filter samples using x-ray fluorescence. Report No.
UCRL-51388. Prepared for U.S. Atomic Energy Commission, by Univ. of
Calif., Lawrence Livermore Laboratory, Livermore, CA.
    10. Dzubay, T.G.; Lamothe, P.J.; and Yoshuda, H. (1977). Polymer
films as calibration standards for X-ray fluorescence analysis. Adv.
X-Ray Anal., 20:411.
    11. Giauque, R.D.; Garrett, R.B.; and Goda, L.Y. (1977).
Calibration of energy-dispersive X-ray spectrometers for analysis of
thin environmental samples. In X-Ray Fluorescence Analysis of
Environmental Samples, T.G. Dzubay, Ed., Ann Arbor Science
Publishers, Ann Arbor, MI, pp. 153-181.
    12. Harmonization of Interlaboratory X-ray Fluorescence
Measurement Uncertainties, Detailed Discussion Paper; August 4,
2006; prepared for the Office of Air Quality Planning and Standards
under EPA contract 68-D-03-038. http://www.epa.gov/ttn/amtic/files/
ambient/pm25/spec/xrfdet.pdf.

0
8. Appendix R is added to read as follows:

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

1. General.

    (a) This appendix explains the data handling conventions and
computations necessary for determining when the primary and
secondary national ambient air quality standards (NAAQS) for lead
(Pb) specified in Sec.  50.16 are met. The NAAQS indicator for Pb is
defined as: lead and its compounds, measured as elemental lead in
total suspended particulate (Pb-TSP), sampled and analyzed by a
Federal reference method (FRM) based on appendix G to this part or
by a Federal equivalent method (FEM) designated in accordance with
part 53 of this chapter. Although Pb-TSP is the lead NAAQS
indicator, surrogate Pb-TSP concentrations shall also be used for
NAAQS comparisons; specifically, valid surrogate Pb-TSP data are
concentration data for lead and its compounds, measured as elemental
lead, in particles with an aerodynamic size of 10 microns or less
(Pb-PM10), sampled and analyzed by an FRM based on
appendix Q to this part or by an FEM designated in accordance with
part 53 of this chapter. Surrogate Pb-TSP data (i.e., Pb-
PM10 data), however, can only be used to show that the Pb
NAAQS were violated (i.e., not met); they can not be used to
demonstrate that the Pb NAAQS were met. Pb-PM10 data used
as surrogate Pb-TSP data shall be processed at face value; that is,
without any transformation or scaling. Data handling and computation
procedures to be used in making comparisons between reported and/or
surrogate Pb-TSP concentrations and the level of the Pb NAAQS are
specified in the following sections.
    (b) Whether to exclude, retain, or make adjustments to the data
affected by exceptional events, including natural events, is
determined by the requirements and process deadlines specified in
Sec. Sec.  50.1, 50.14, and 51.930 of this chapter.
    (c) The terms used in this appendix are defined as follows:
    Annual monitoring network plan refers to the plan required by
section 58.10 of this chapter.
    Creditable samples are samples that are given credit for data
completeness. They include valid samples collected on required
sampling days and valid ``make-up'' samples taken for missed or
invalidated samples on required sampling days.
    Daily values for Pb refer to the 24-hour mean concentrations of
Pb (Pb-TSP or Pb-PM10), measured from midnight to
midnight (local standard time), that are used in NAAQS computations.

    Design value is the site-level metric (i.e., statistic) that is
compared to the NAAQS level to determine compliance; the design
value for the Pb NAAQS is selected according to the procedures in
this appendix from among the valid three-month Pb-TSP and surrogate
Pb-TSP (Pb-PM10) arithmetic mean concentration for the
38-month period consisting of the most recent 3-year calendar period
plus two previous months (i.e., 36 3-month periods) using the last
month of each 3-month period as the period of report.
    Extra samples are non-creditable samples. They are daily values
that do not occur on scheduled sampling days and that can not be
used as ``make-up samples'' for missed or invalidated scheduled
samples. Extra samples are used in mean calculations. For purposes
of determining whether a sample must be treated as a make-up sample
or an extra sample, Pb-TSP and Pb-PM10 data collected
before January 1, 2009 will be treated with an assumed scheduled
sampling frequency of every sixth day.
    Make-up samples are samples taken to replace missed or
invalidated required scheduled samples. Make-ups can be made by
either the primary or collocated (same size fraction) instruments;
to be considered a valid make-up, the sampling must be conducted
with equipment and procedures that meet the requirements for
scheduled sampling. Make-up samples are either taken before the next
required sampling day or exactly one week after the missed (or
voided) sampling day. Make-up samples can not span years; that is,
if a scheduled sample for December is missed (or voided), it can not
be made up in January. Make-up samples, however, may span months,
for example a missed sample on January 31 may be made up on February
1, 2, 3, 4, 5, or 7 (with an assumed sampling frequency of every
sixth day). Section 3(e) explains how such month-spanning make-up
samples are to be treated for purposes of data completeness and mean
calculations. Only two make-up samples are permitted each calendar
month; these are counted according to the month in which the miss
and not the makeup occurred. For purposes of determining whether a
sample must be treated as a make-up sample or an extra sample, Pb-
TSP and Pb-PM10 data collected before January 1, 2009
will be treated with an assumed scheduled sampling frequency of
every sixth day.
    Monthly mean refers to an arithmetic mean, calculated as
specified in section 6(a) of this appendix. Monthly means are
computed at each monitoring site separately for Pb-TSP and Pb-
PM10 (i.e., by site-parameter-year-month).
    Parameter refers either to Pb-TSP or to Pb-PM10.
    Pollutant Occurrence Code (POC) refers to a numerical code (1,
2, 3, etc.) used to distinguish the data from two or more monitors
for the same parameter at a single monitoring site.
    Scheduled sampling day means a day on which sampling is
scheduled based on the required sampling frequency for the
monitoring site, as provided in section 58.12 of this chapter.
    Three-month means are arithmetic averages of three consecutive
monthly means. Three-month means are computed on a rolling,
overlapping basis. Each distinct monthly mean will be included in
three different 3-month means; for example, in a given year, a
November mean would be included in: (1) The September-October-
November 3-month mean, (2) the October-November-December 3-month
mean, and (3) the November-December-January(of the following year)
3-month mean. Three-month means are computed separately for each
parameter per section 6(a) (and are referred to as 3-month parameter
means) and are validated according to the criteria specified in
section 4(c). The parameter-specific 3-month means are then
prioritized according to section 2(a) to determine a single 3-month
site mean.
    Year refers to a calendar year.
    2. Use of Pb-PM10 Data as Surrogate Pb-TSP Data.
    (a) As stipulated in section 2.10 of Appendix C to 40 CFR part
58, at some mandatory Pb monitoring locations, monitoring agencies
are required to sample for Pb as Pb-TSP, and at other mandatory Pb
monitoring sites, monitoring agencies are permitted to monitor for
Pb-PM10 in lieu of Pb-TSP. In either situation, valid
collocated Pb data for the other parameter may be produced.
Additionally, there may be non-required monitoring locations that
also produce valid Pb-TSP and/or valid Pb-PM10 data. Pb-
TSP data and Pb-PM10 data are always processed separately
when computing monthly and 3-month parameter means; monthly and 3-
month parameter means are validated according to the criteria stated
in section 4 of this appendix. Three-month ``site'' means, which are
the final valid 3-month mean from which a design value is
identified, are determined from the one or two available valid 3-
month parameter means according to the following prioritization
which applies to all Pb monitoring locations.
    (i) Whenever a valid 3-month Pb-PM10 mean shows a
violation and either is greater than a corresponding (collocated) 3-
month Pb-TSP mean or there is no corresponding valid 3-month Pb-TSP
mean present, then that 3-month Pb-PM10 mean will be the
site-level mean for that (site's) 3-month period.
    (ii) Otherwise (i.e., there is no valid violating 3-month Pb-
PM10 that exceeds a corresponding 3-month Pb-TSP mean),
    (A) If a valid 3-month Pb-TSP mean exists, then it will be the
site-level mean for that (site's) 3-month period, or
    (B) If a valid 3-month Pb-TSP mean does not exist, then there is
no valid 3-month site mean for that period (even if a valid non-
violating 3-month Pb-PM10 mean exists).
    (b) As noted in section 1(a) of this appendix, FRM/FEM Pb-
PM10 data will be processed at face value (i.e., at
reported concentrations) without adjustment when computing means and
making NAAQS comparisons.
    3. Requirements for Data Used for Comparisons With the Pb NAAQS
and Data Reporting Considerations.
    (a) All valid FRM/FEM Pb-TSP data and all valid FRM/FEM Pb-
PM10 data submitted to EPA's Air Quality System (AQS), or
otherwise available to EPA, meeting the requirements of part 58 of
this chapter including appendices A, C, and E shall be used in
design value calculations. Pb-TSP and Pb-PM10 data
representing sample collection periods prior to January 1, 2009
(i.e., ``pre-rule'' data) will also be considered valid for NAAQS
comparisons and related attainment/nonattainment determinations if
the sampling and analysis methods that were utilized to collect that
data were consistent with previous or newly designated FRMs or FEMs
and with either the provisions of part 58 of this chapter including
appendices A, C, and E that were in effect at the time of original
sampling or that are in effect at the time of the attainment/
nonattainment determination, and if such data are submitted to AQS
prior to September 1, 2009.
    (b) Pb-TSP and Pb-PM10 measurement data are reported
to AQS in units of micrograms per cubic meter ([mu]g/m3)
at local conditions (local temperature and pressure, LC) to three
decimal places; any additional digits to the right of the third
decimal place are truncated. Pre-rule Pb-TSP and Pb-PM10
concentration data that were reported in standard conditions
(standard temperature and standard pressure, STP) will not require a
conversion to local conditions but rather, after truncating to three
decimal places and processing as stated in this appendix, shall be
compared ``as is'' to the NAAQS (i.e., the LC to STP conversion
factor will be assumed to be one). However, if the monitoring agency
has retroactively resubmitted Pb-TSP or Pb-PM10 pre-rule
data converted from STP to LC based on suitable meteorological data,
only the LC data will be used.
    (c) At each monitoring location (site), Pb-TSP and Pb-
PM10 data are to be processed separately when selecting
daily data by day (as specified in section 3(d) of this appendix),
when aggregating daily data by month (per section 6(a)), and when
forming 3-month means (per section 6(b)). However, when deriving
(i.e., identifying) the design value for the 38-month period, 3-
month means for the two data types may be considered together; see
sections 2(a) and 4(e) of this appendix for details.
    (d) Daily values for sites will be selected for a site on a size
cut (Pb-TSP or Pb-PM10, i.e., ``parameter'') basis; Pb-
TSP concentrations and Pb-PM10 concentrations shall not
be commingled in these determinations. Site level, parameter-
specific daily values will be selected as follows:
    (i) The starting dataset for a site-parameter shall consist of
the measured daily concentrations recorded from the designated
primary FRM/FEM monitor for that parameter. The primary monitor for
each parameter shall be designated in the appropriate state or local
agency annual Monitoring Network Plan. If no primary monitor is
designated, the Administrator will select which monitor to treat as
primary. All daily values produced by the primary sampler are
considered part of the site-parameter data record (i.e., that site-
parameter's set of daily values); this includes all creditable
samples and all extra samples. For pre-rule Pb-TSP and Pb-
PM10 data, valid data records present in AQS for the
monitor with the lowest occurring Pollutant Occurrence Code (POC),
as selected on a site-parameter-daily basis, will constitute the
site-

parameter data record. Where pre-rule Pb-TSP data (or subsequent
non-required Pb-TSP or Pb-PM10 data) are reported in
``composite'' form (i.e., multiple filters for a month of sampling
that are analyzed together), the composite concentration will be
used as the site-parameter monthly mean concentration if there are
no valid daily Pb-TSP data reported for that month with a lower POC.
    (ii) Data for the primary monitor for each parameter shall be
augmented as much as possible with data from collocated (same
parameter) FRM/FEM monitors. If a valid 24-hour measurement is not
produced from the primary monitor for a particular day (scheduled or
otherwise), but a valid sample is generated by a collocated (same
parameter) FRM/FEM instrument, then that collocated value shall be
considered part of the site-parameter data record (i.e., that site-
parameter's monthly set of daily values). If more than one valid
collocated FRM/FEM value is available, the mean of those valid
collocated values shall be used as the daily value. Note that this
step will not be necessary for pre-rule data given the daily
identification presumption for the primary monitor.
    (e) All daily values in the composite site-parameter record are
used in monthly mean calculations. However, not all daily values are
given credit towards data completeness requirements. Only
``creditable'' samples are given credit for data completeness.
Creditable samples include valid samples on scheduled sampling days
and valid make-up samples. All other types of daily values are
referred to as ``extra'' samples. Make-up samples taken in the
(first week of the) month after the one in which the miss/void
occurred will be credited for data capture in the month of the miss/
void but will be included in the month actually taken when computing
monthly means. For example, if a make-up sample was taken in
February to replace a missed sample scheduled for January, the make-
up concentration would be included in the February monthly mean but
the sample credited in the January data capture rate.
    4. Comparisons With the Pb NAAQS.
    (a) The Pb NAAQS is met at a monitoring site when the identified
design value is valid and less than or equal to 0.15 micrograms per
cubic meter ([mu]g/m3). A Pb design value that meets the
NAAQS (i.e., 0.15 [mu]g/m3 or less), is considered valid
if it encompasses 36 consecutive valid 3-month site means
(specifically for a 3-year calendar period and the two previous
months). For sites that begin monitoring Pb after this rule is
effective but before January 15, 2010 (or January 15, 2011), a 2010-
2012 (or 2011-2013) Pb design value that meets the NAAQS will be
considered valid if it encompasses at least 34 consecutive valid 3-
month means (specifically encompassing only the 3-year calendar
period). See 4(c) of this appendix for the description of a valid 3-
month mean and section 6(d) for the definition of the design value.
    (b) The Pb NAAQS is violated at a monitoring site when the
identified design value is valid and is greater than 0.15 [mu]g/
m3, no matter whether determined from Pb-TSP or Pb-
PM10 data. A Pb design value greater than 0.15 [mu]g/
m3 is valid no matter how many valid 3-month means in the
3-year period it encompasses; that is, a violating design value is
valid even if it (i.e., the highest 3-month mean) is the only valid
3-month mean in the 3-year timeframe. Further, a site does not have
to monitor for three full calendar years in order to have a valid
violating design value; a site could monitor just three months and
still produce a valid (violating) design value.
    (c)(i) A 3-month parameter mean is considered valid (i.e., meets
data completeness requirements) if the average of the data capture
rate of the three constituent monthly means (i.e., the 3-month data
capture rate) is greater than or equal to 75 percent. Monthly data
capture rates (expressed as a percentage) are specifically
calculated as the number of creditable samples for the month
(including any make-up samples taken the subsequent month for missed
samples in the month in question, and excluding any make-up samples
taken in the month in question for missed samples in the previous
month) divided by the number of scheduled samples for the month, the
result then multiplied by 100 but not rounded. The 3-month data
capture rate is the sum of the three corresponding unrounded monthly
data capture rates divided by three and the result rounded to the
nearest integer (zero decimal places). As noted in section 3(c), Pb-
TSP and Pb-PM10 daily values are processed separately
when calculating monthly means and data capture rates; a Pb-TSP
value cannot be used as a make-up for a missing Pb-PM10
value or vice versa. For purposes of assessing data capture, Pb-TSP
and Pb-PM10 data collected before January 1, 2009 will be
treated with an assumed scheduled sampling frequency of every sixth
day.
    (ii) A 3-month parameter mean that does not have at least 75
percent data capture and thus is not considered valid under 4(c)(i)
shall be considered valid (and complete) if it passes either of the
two following ``data substitution'' tests, one such test for
validating an above NAAQS-level (i.e., violating) 3-month Pb-TSP or
Pb-PM10 mean (using actual ``low'' reported values from
the same site at about the same time of the year (i.e., in the same
month) looking across three or four years), and the second test for
validating a below-NAAQS level 3-month Pb-TSP mean (using actual
``high'' values reported for the same site at about the same time of
the year (i.e., in the same month) looking across three or four
years). Note that both tests are merely diagnostic in nature
intending to confirm that there is a very high likelihood if not
certainty that the original mean (the one with less than 75% data
capture) reflects the true over/under NAAQS-level status for that 3-
month period; the result of one of these data substitution tests
(i.e., a ``test mean'', as defined in section 4(c)(ii)(A) or
4(c)(ii)(B)) is not considered the actual 3-month parameter mean and
shall not be used in the determination of design values. For both
types of data substitution, substitution is permitted only if there
are available data points from which to identify the high or low 3-
year month-specific values, specifically if there are at least 10
data points total from at least two of the three (or four for
November and December) possible year-months. Data substitution may
only use data of the same parameter type.
    (A) The ``above NAAQS level'' test is as follows: Data
substitution will be done in each month of the 3-month period that
has less than 75 percent data capture; monthly capture rates are
temporarily rounded to integers (zero decimals) for this evaluation.
If by substituting the lowest reported daily value for that month
(year non-specific; e.g., for January) over the 38-month design
value period in question for missing scheduled data in the deficient
months (substituting only enough to meet the 75 percent data capture
minimum), the computation yields a recalculated test 3-month
parameter mean concentration above the level of the standard, then
the 3-month period is deemed to have passed the diagnostic test and
the level of the standard is deemed to have been exceeded in that 3-
month period. As noted in section 4(c)(ii), in such a case, the 3-
month parameter mean of the data actually reported, not the
recalculated (``test'') result including the low values, shall be
used to determine the design value.
    (B) The ``below NAAQS level'' test is as follows: Data
substitution will be performed for each month of the 3-month period
that has less than 75 percent but at least 50 percent data capture;
if any month has less than 50% data capture then the 3-month mean
can not utilize this substitution test. Also, incomplete 3-month Pb-
PM10 means can not utilize this test. A 3-month Pb-TSP
mean with less than 75% data capture shall still be considered valid
(and complete) if, by substituting the highest reported daily value,
month-specific, over the 3-year design value period in question, for
all missing scheduled data in the deficient months (i.e., bringing
the data capture rate up to 100%), the computation yields a
recalculated 3-month parameter mean concentration equal or less than
the level of the standard (0.15 [mu]g/m3), then the 3-
month mean is deemed to have passed the diagnostic test and the
level of the standard is deemed not to have been exceeded in that 3-
month period (for that parameter). As noted in section 4(c)(ii), in
such a case, the 3-month parameter mean of the data actually
reported, not the recalculated (``test'') result including the high
values, shall be used to determine the design value.
    (d) Months that do not meet the completeness criteria stated in
4(c)(i) or 4(c)(ii), and design values that do not meet the
completeness criteria stated in 4(a) or 4(b), may also be considered
valid (and complete) with the approval of, or at the initiative of,
the Administrator, who may consider factors such as monitoring site
closures/moves, monitoring diligence, the consistency and levels of
the valid concentration measurements that are available, and nearby
concentrations in determining whether to use such data.
    (e) The site-level design value for a 38-month period (three
calendar years plus two previous months) is identified from the
available (between one and 36) valid 3-month site means. In a
situation where there are valid 3-month means for both parameters

(Pb-TSP and Pb-PM10), the mean originating from the
reported Pb-TSP data will be the one deemed the site-level monthly
mean and used in design value identifications unless the Pb-
PM10 mean shows a violation of the NAAQS and exceeds the
Pb-TSP mean; see section 2(a) for details. A monitoring site will
have only one site-level 3-month mean per 3-month period; however,
the set of site-level 3-month means considered for design value
identification (i.e., one to 36 site-level 3-month means) can be a
combination of Pb-TSP and Pb-PM10 data.
    (f) The procedures for calculating monthly means and 3-month
means, and identifying Pb design values are given in section 6 of
this appendix.
    5. Rounding Conventions.
    (a) Monthly means and monthly data capture rates are not
rounded.
    (b) Three-month means shall be rounded to the nearest hundredth
[mu]g/m3 (0.xx). Decimals 0.xx5 and greater are rounded
up, and any decimal lower than 0.xx5 is rounded down. E.g., a 3-
month mean of 0.104925 rounds to 0.10 and a 3-month mean of .10500
rounds to 0.11. Three-month data capture rates, expressed as a
percent, are round to zero decimal places.
    (c) Because a Pb design value is simply a (highest) 3-month mean
and because the NAAQS level is stated to two decimal places, no
additional rounding beyond what is specified for 3-month means is
required before a design value is compared to the NAAQS.
    6. Procedures and Equations for the Pb NAAQS.
    (a)(i) A monthly mean value for Pb-TSP (or Pb-PM10)
is determined by averaging the daily values of a calendar month
using equation 1 of this appendix, unless the Administrator chooses
to exercise his discretion to use the alternate approach described
in 6(a)(ii).
[GRAPHIC] [TIFF OMITTED] TR12NO08.001

Where:

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

    (a)(ii) The Administrator may at his discretion use the
following alternate approach to calculating the monthly mean
concentration if the number of extra sampling days during a month is
greater than the number of successfully completed scheduled and
make-up sample days in that month. In exercising his discretion, the
Administrator will consider whether the approach specified in
6(a)(i) might in the Administrator's judgment result in an
unrepresentative value for the monthly mean concentration. This
provision is to protect the integrity of the monthly and 3-month
mean concentration values in situations in which, by intention or
otherwise, extra sampling days are concentrated in a period during
which ambient concentrations are particularly high or low. The
alternate approach is to average all extra and make-up samples (in
the given month) taken after each scheduled sampling day (``Day X'')
and before the next scheduled sampling day (e.g., ``Day X+6'', in
the case of one-in-six sampling) with the sample taken on Day X
(assuming valid data was obtained on the scheduled sampling day),
and then averaging these averages to calculate the monthly mean.
This approach has the effect of giving approximately equal weight to
periods during a month that have equal number of days, regardless of
how many samples were actually obtained during the periods, thus
mitigating the potential for the monthly mean to be distorted. The
first day of scheduled sampling typically will not fall on the first
day of the calendar month, and there may be make-up and/or extra
samples (in that same calendar month) preceding the first scheduled
day of the month. These samples will not be shifted into the
previous month's mean concentration, but rather will stay associated
with their actual calendar month as follows. Any extra and make-up
samples taken in a month before the first scheduled sampling day of
the month will be associated with and averaged with the last
scheduled sampling day of that same month.
    (b) Three-month parameter means are determined by averaging
three consecutive monthly means of the same parameter using Equation
2 of this appendix.
[GRAPHIC] [TIFF OMITTED] TR12NO08.002

Where:

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

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

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

0
9. The authority citation for part 51 continues to read as follows:

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

0
10. Section 51.117 is amended by revising paragraph (e)(1) to read as
follows:

Sec.  51.117  Additional provisions for lead.

* * * * *
    (e) * * *
    (1) The point source inventory on which the summary of the baseline
for lead emissions inventory is based must contain all sources that
emit 0.5 or more tons of lead per year.
* * * * *

PART 53--AMBIENT AIR MONITORING REFERENCE AND EQUIVALENT METHODS

0
11. The authority citation for part 53 continues to read as follows:

    Authority: Sec. 301(a) of the Clean Air Act (42 U.S.C. sec.
1857g(a)), as amended by sec. 15(c)(2) of Pub. L. 91-604, 84 Stat.
1713, unless otherwise noted.

Subpart C--[Amended]

0
12. Section 53.33 is revised to read as follows:

Sec.  53.33  Test Procedure for Methods for Lead (Pb).

    (a) General. The reference method for Pb in TSP includes two parts,
the reference method for high-volume sampling of TSP as specified in 40
CFR 50, Appendix B and the analysis method for Pb in TSP as specified
in 40 CFR 50, Appendix G. Correspondingly, the reference method for Pb
in PM10 includes the reference method for low-volume
sampling of PM10 in 40 CFR 50, Appendix O and the analysis
method of Pb in PM10 as specified in 40 CFR 50, Appendix Q.
This section explains the procedures for demonstrating the equivalence
of either a candidate method for Pb in TSP to the high-volume reference
methods, or a candidate method for Pb in PM10 to the low-
volume reference methods.
    (1) Pb in TSP--A candidate method for Pb in TSP specifies reporting
of Pb concentrations in terms of standard temperature and pressure.
Comparisons of candidate methods to the reference method in 40 CFR 50,
Appendix G must be made in a consistent manner with regard to
temperature and pressure.
    (2) Pb in PM10--A candidate method for Pb in
PM10 must specify reporting of Pb concentrations in terms of
local conditions of temperature and pressure, which will be compared to
similarly reported concentrations from the reference method in 40 CFR
50 Appendix Q.
    (b) Comparability. Comparability is shown for Pb methods when the
differences between:

    (1) Measurements made by a candidate method, and
    (2) Measurements made by the reference method on simultaneously
collected Pb samples (or the same sample, if applicable), are less than
or equal to the values specified in table C-3 of this subpart.
    (c) Test measurements. Test measurements may be made at any number
of test sites. Augmentation of pollutant concentrations is not
permitted, hence an appropriate test site or sites must be selected to
provide Pb concentrations in the specified range.
    (d) Collocated samplers. The ambient air intake points of all the
candidate and reference method collocated samplers shall be positioned
at the same height above the ground level, and between 2 meters (1
meter for samplers with flow rates less than 200 liters per minute (L/
min)) and 4 meters apart. The samplers shall be oriented in a manner
that will minimize spatial and wind directional effects on sample
collection.
    (e) Sample collection. Collect simultaneous 24-hour samples of Pb
at the test site or sites with both the reference and candidate methods
until at least 10 sample pairs have been obtained.
    (1) A candidate method for Pb in TSP which employs a sampler and
sample collection procedure that are identical to the sampler and
sample collection procedure specified in the reference method in 40 CFR
part 50, Appendix B, but uses a different analytical procedure than
specified in 40 CFR Appendix G, may be tested by analyzing pairs of
filter strips taken from a single TSP reference sampler operated
according to the procedures specified by that reference method.
    (2) A candidate method for Pb in PM10 which employs a
sampler and sample collection procedure that are identical to the
sampler and sample collection procedure specified in the reference
method in 40 CFR part 50, Appendix O, but uses a different analytical
procedure than specified in 40 CFR Appendix Q, requires the use of two
PM10 reference samplers because a single 46.2-mm filter from
a reference sampler may not be divided prior to analysis. It is
possible to analyze a 46.2-mm filter first with the non-destructive X-
ray Fluorescence (XRF) FRM and subsequently extract the filter for
other analytical techniques. If the filter is subject to XRF with
subsequent extraction for other analyses, then a single PM10
reference sampler may be used for sample collection.
    (3) A candidate method for Pb in TSP or Pb in PM10 which
employs a direct reading (e.g., continuous or semi-continuous sampling)
method that uses the same sampling inlet and flow rate as the FRM and
the same or different analytical procedure may be tested. The direct
measurements are then aggregated to 24-hour equivalent concentrations
for comparison with the FRM. For determining precision in section (k),
two collocated direct reading devices must be used.
    (f) Audit samples. Three audit samples must be obtained from the
address given in Sec.  53.4(a). For Pb in TSP collected by the high-
volume sampling method, the audit samples are \3/4\ x 8-inch glass
fiber strips containing known amounts of Pb in micrograms per strip
([mu]g/strip) equivalent to the following nominal percentages of the
National Ambient Air Quality Standard (NAAQS): 30%, 100%, and 250%. For
Pb in PM10 collected by the low-volume sampling method, the
audit samples are 46.2-mm polytetrafluorethylene (PTFE) filters
containing known amounts of Pb in micrograms per filter ([mu]g/filter)
equivalent to the same percentages of the NAAQS: 30%, 100%, and 250%.
The true amount of Pb (Tqi), in total [mu]g/strip (for TSP) or total
[mu]g/filter (for PM10), will be provided for each audit
sample.
    (g) Filter analysis.
    (1) For both the reference method samples (e) and the audit samples
(f), analyze each filter or filter extract three times in accordance
with the reference method analytical procedure. This applies to both
the Pb in TSP and Pb in PM10 methods. The analysis of
replicates should not be performed sequentially, i.e., a single sample
should not be analyzed three times in sequence. Calculate the indicated
Pb concentrations for the reference method samples in micrograms per
cubic meter ([mu]g/m\3\) for each analysis of each filter. Calculate
the indicated total Pb amount for the audit samples in [mu]g/strip for
each analysis of each strip or [mu]g/filter for each analysis of each
audit filter. Label these test results as R1A,
R1B, R1C, R2A, R2B, etc.,
Q1A, Q1B, Q1C, etc., where R denotes
results from the reference method samples; Q denotes results from the
audit samples; 1, 2, 3 indicate the filter number, and A, B, C indicate
the first, second, and third analysis of each filter, respectively.
    (2) For the candidate method samples, analyze each sample filter or
filter extract three times and calculate, in accordance with the
candidate method, the indicated Pb concentration in [mu]g/m
3 for each analysis of each filter. The analysis of
replicates should not be performed sequentially. Label these test
results as C1A, C1B, C2C, etc., where
C denotes results from the candidate method. For candidate methods
which provide a direct reading or measurement of Pb concentrations
without a separable procedure,
C1A=C1B=C1C,
C2A=C2B=C2C, etc.
    (h) Average Pb concentration. For the reference method, calculate
the average Pb concentration for each filter by averaging the
concentrations calculated from the three analyses as described in
(g)(1) using equation 1 of this section:
[GRAPHIC] [TIFF OMITTED] TR12NO08.003

Where, i is the filter number.

    (i) Analytical Bias.
    (1) For the audit samples, calculate the average Pb concentration
for each strip or filter analyzed by the reference method by averaging
the concentrations calculated from the three analyses as described in
(g)(1) using equation 2 of this section:
[GRAPHIC] [TIFF OMITTED] TR12NO08.004

Where, i is audit sample number.

    (2) Calculate the percent difference (Dq) between the
average Pb concentration for each audit sample and the true Pb
concentration (Tq) using equation 3 of this section:
[GRAPHIC] [TIFF OMITTED] TR12NO08.005

    (3) If any difference value (Dqi) exceeds 5
percent, the bias of the reference method analytical procedure is out-
of-control. Corrective action must be taken to determine the source of
the error(s) (e.g., calibration standard discrepancies, extraction
problems, etc.) and the reference method and audit sample
determinations must be repeated according to paragraph (g) of this
section, or the entire test procedure (starting with paragraph (e) of
this section) must be repeated.
    (j) Acceptable filter pairs. Disregard all filter pairs for which
the Pb concentration, as determined in paragraph (h) of this section by
the average of the three reference method determinations, falls outside
the range of 30% to 250% of the Pb NAAQS level in [mu]g/m3
for Pb in both TSP and PM10. All remaining filter pairs must
be subjected to the tests for precision and comparability in paragraphs
(k) and (l) of this section. At least five filter pairs

must be within the specified concentration range for the tests to be
valid.
    (k) Test for precision.
    (1) Calculate the precision (P) of the analysis (in percent) for
each filter and for each method, as the maximum minus the minimum
divided by the average of the three concentration values, using
equation 4 or equation 5 of this section:
[GRAPHIC] [TIFF OMITTED] TR12NO08.006

Where, i indicates the filter number.

    (2) If a direct reading candidate method is tested, the precision
is determined from collocated devices using equation 5 above.
    (3) If any reference method precision value (PRi)
exceeds 15 percent, the precision of the reference method analytical
procedure is out-of-control. Corrective action must be taken to
determine the source(s) of imprecision, and the reference method
determinations must be repeated according to paragraph (g) of this
section, or the entire test procedure (starting with paragraph (e) of
this section) must be repeated.
    (4) If any candidate method precision value (PCi)
exceeds 15 percent, the candidate method fails the precision test.
    (5) The candidate method passes this test if all precision values
(i.e., all PRi's and all PCi's) are less than 15
percent.
    (l) Test for comparability.
    (1) For each filter or analytical sample pair, calculate all nine
possible percent differences (D) between the reference and candidate
methods, using all nine possible combinations of the three
determinations (A, B, and C) for each method using equation 6 of this
section:
[GRAPHIC] [TIFF OMITTED] TR12NO08.007

Where, i is the filter number, and n numbers from 1 to 9 for the
nine possible difference combinations for the three determinations
for each method (j = A, B, C, candidate; k = A, B, C, reference).

    (2) If none of the percent differences (D) exceeds 20
percent, the candidate method passes the test for comparability.
    (3) If one or more of the percent differences (D) exceed 20 percent, the candidate method fails the test for
comparability.
    (4) The candidate method must pass both the precision test
(paragraph (k) of this section) and the comparability test (paragraph
(l) of this section) to qualify for designation as an equivalent
method.
    (m) Method Detection Limit (MDL). Calculate the estimated MDL using
the guidance provided in 40 CFR, Part 136 Appendix B. It is essential
that all sample processing steps of the analytical method be included
in the determination of the method detection limit. Take a minimum of
seven blank filters from each lot to be used and calculate the
detection limit by processing each through the entire candidate
analytical method. Make all computations according to the defined
method with the final results in [mu]g/m3. The MDL of the
candidate method must be equal to, or less than 5% of the level of the
Pb NAAQS.

0
13. Table C-3 to Subpart C of Part 53 is revised to read as follows:

Table C-3 to Subpart C of Part 53--Test Specifications for Pb in TSP and
                           Pb in PM10 Methods
------------------------------------------------------------------------

------------------------------------------------------------------------
Concentration range equivalent to           30% to 250%
 percentage of NAAQS in [mu]g/m\3\.
Minimum number of 24-hr measurements......  5
Maximum reference method analytical bias,   5%
 Dq.
Maximum precision, PR or PC...............  <=15%
Maximum difference (D)....................  20%
Estimated Method Detection Limit (MDL),     5% of NAAQS level.
 [mu]g/m\3\.
------------------------------------------------------------------------

PART 58--AMBIENT AIR QUALITY SURVEILLANCE

0
14. The authority citation for part 58 continues to read as follows:

    Authority: 42 U.S.C. 7403, 7410, 7601(a), 7611, and 7619.

Subpart B--[Amended]

0
15. Section 58.10, is amended by added paragraph subsections (a)(4) and
adding paragraph (b)(9) to read as follows:

Sec.  58.10  Annual monitoring network plan and periodic network
assessment.

* * * * *
    (a) * * *
    (4) A plan for establishing Pb monitoring sites in accordance with
the requirements of appendix D to this part shall be submitted to the
EPA Regional Administrator no later than July 1, 2009 as part of the
annual network plan required in paragraph (a)(1) of this section. The
plan shall provide for the required source-oriented Pb monitoring sites
to be operational by January 1, 2010, and for all required non-source-
oriented Pb monitoring sites to be operational by January 1, 2011.
Specific site locations for the sites to be operational by January 1,
2011 are not required as part of the July 1, 2009 annual network plan,
but shall be included in the annual network plan due to be submitted to
the EPA Regional Administrator on July 1, 2010.
* * * * *
    (b) * * *
    (9) The designation of any Pb monitors as either source-oriented or
non-source-oriented according to Appendix D to 40 CFR part 58.
    (10) Any source-oriented monitors for which a waiver has been
requested or granted by the EPA Regional Administrator as allowed for
under paragraph 4.5(a)(ii) of Appendix D to 40 CFR part 58.
    (11) Any source-oriented or non-source-oriented site for which a
waiver has been requested or granted by the EPA Regional Administrator
for the use of Pb-PM10 monitoring in lieu of Pb-TSP
monitoring as allowed for under paragraph 2.10 of Appendix C to 40 CFR
part 58.
* * * * *

0
16. Section 58.13 is amended by revising paragraph (b) to read as
follows:

Sec.  58.13  Monitoring network completion.

* * * * *
    (b) Not withstanding specific dates included in this part,
beginning January 1, 2008, when existing networks are not in
conformance with the minimum number of required monitors specified in
this part, additional required monitors must be identified in the next
applicable annual monitoring network plan, with monitoring operation
beginning by January 1 of the following year. To allow sufficient time
to prepare and comment on Annual Monitoring Network Plans, only
monitoring requirements effective 120 days prior to the required
submission date of the plan (i.e., 120 days prior to July 1 of each
year) shall be included in that year's annual monitoring network plan.
0
17. Section 58.16 is amended by revising paragraph (a) to read as
follows:

Sec.  58.16  Data submittal and archiving requirements.

    (a) The State, or where appropriate, local agency, shall report to
the Administrator, via AQS all ambient air quality data and associated
quality assurance data for SO2; CO; O3;
NO2;

NO; NOY; NOX; Pb-TSP mass concentration; Pb-
PM10 mass concentration; PM10 mass concentration;
PM2.5 mass concentration; for filter-based PM2.5
FRM/FEM the field blank mass, sampler-generated average daily
temperature, and sampler-generated average daily pressure; chemically
speciated PM2.5 mass concentration data; PM10-2.5
mass concentration; chemically speciated PM10-2.5 mass
concentration data; meteorological data from NCore and PAMS sites;
average daily temperature and average daily pressure for Pb sites if
not already reported from sampler generated records; and metadata
records and information specified by the AQS Data Coding Manual (http:/
/www.epa.gov/ttn/airs/airsaqs/manuals/manuals.htm). The State, or where
appropriate, local agency, may report site specific meteorological
measurements generated by onsite equipment (meteorological instruments,
or sampler generated) or measurements from the nearest airport
reporting ambient pressure and temperature. Such air quality data and
information must be submitted directly to the AQS via electronic
transmission on the specified quarterly schedule described in paragraph
(b) of this section.
* * * * *

Subpart D--[Amended]

0
18. Section 58.20 is amended by revising paragraph (e) to read as
follows:

Sec.  58.20  Special purpose monitors (SPM).

* * * * *
    (e) If an SPM using an FRM, FEM, or ARM is discontinued within 24
months of start-up, the Administrator will not designate an area as
nonattainment for the CO, SO2, NO2, or 24-hour
PM10 NAAQS solely on the basis of data from the SPM. Such
data are eligible for use in determinations of whether a nonattainment
area has attained one of these NAAQS.
* * * * *

0
19. Appendix A to Part 58 is amended to read as follows:
0
a. Revising paragraph 1,
0
b. Adding paragraph <IP_ADDRESS>,
0
c. Revising paragraph 3.3.4,
0
d. Revising paragraph 4c,
0
e. Revising paragraph 4.4,
0
f. Removing paragraph 4.5 and
0
g. Revising Table A-2.

Appendix A to Part 58--Quality Assurance Requirements for SLAMS, SPMs
and PSD Air Monitoring

* * * * *
    1. General Information.
    This appendix specifies the minimum quality system requirements
applicable to SLAMS air monitoring data and PSD data for the
pollutants SO2, NO2, O3, CO, Pb,
PM2.5, PM10 and PM10-2.5 submitted
to EPA. This appendix also applies to all SPM stations using FRM,
FEM, or ARM methods which also meet the requirements of Appendix E
of this part. Monitoring organizations are encouraged to develop and
maintain quality systems more extensive than the required minimums.
The permit-granting authority for PSD may require more frequent or
more stringent requirements. Monitoring organizations may, based on
their quality objectives, develop and maintain quality systems
beyond the required minimum. Additional guidance for the
requirements reflected in this appendix can be found in the
``Quality Assurance Handbook for Air Pollution Measurement
Systems'', volume II, part 1 (see reference 10 of this appendix) and
at a national level in references 1, 2, and 3 of this appendix.
* * * * *
    <IP_ADDRESS> Measurement Uncertainty for Pb Methods. The goal for
acceptable measurement uncertainty is defined for precision as an
upper 90 percent confidence limit for the coefficient variation (CV)
of 20 percent and for bias as an upper 95 percent confidence limit
for the absolute bias of 15 percent.
* * * * *
    3.3.4 Pb Methods.
    <IP_ADDRESS> Flow Rates. For the Pb Reference Methods (40 CFR Part
50, appendix G and appendix Q) and associated FEMs, the flow rates
of the Pb samplers shall be verified and audited using the same
procedures described in sections 3.3.2 and 3.3.3 of this appendix.
    <IP_ADDRESS> Pb Analysis Audits. Each calendar quarter or sampling
quarter (PSD), audit the Pb Reference Method analytical procedure
using filters containing a known quantity of Pb. These audit filters
are prepared by depositing a Pb solution on unexposed filters and
allowing them to dry thoroughly. The audit samples must be prepared
using batches of reagents different from those used to calibrate the
Pb analytical equipment being audited. Prepare audit samples in the
following concentration ranges:

------------------------------------------------------------------------
          Range            Equivalent ambient Pb concentration, [mu]g/m3
------------------------------------------------------------------------
1........................  30-100% of Pb NAAQS.
2........................  200-300% of Pb NAAQS.
------------------------------------------------------------------------

    (a) Audit samples must be extracted using the same extraction
procedure used for exposed filters.
    (b) Analyze three audit samples in each of the two ranges each
quarter samples are analyzed. The audit sample analyses shall be
distributed as much as possible over the entire calendar quarter.
    (c) Report the audit concentrations (in [mu]g Pb/filter or
strip) and the corresponding measured concentrations (in [mu]g Pb/
filter or strip) using AQS unit code 077. The percent differences
between the concentrations are used to calculate analytical accuracy
as described in section 4.1.3 of this appendix.
    (d) The audits of an equivalent Pb method are conducted and
assessed in the same manner as for the reference method. The flow
auditing device and Pb analysis audit samples must be compatible
with the specific requirements of the equivalent method.
    <IP_ADDRESS> Collocated Sampling. The collocated sampling
requirements for Pb-TSP and Pb-PM10 shall be determined
using the same procedures described in sections 3.3.1 of this
appendix with the exception that the first collocated Pb site
selected must be the site measuring the highest Pb concentrations in
the network. If the site is impractical, alternative sites, approved
by the EPA Regional Administrator, may be selected. If additional
collocated sites are necessary, collocated sites may be chosen that
reflect average ambient air Pb concentrations in the network.
    <IP_ADDRESS> Pb Performance Evaluation Program (PEP) Procedures. Each
year, one performance evaluation audit, as described in section
3.2.7 of this appendix, must be performed at one Pb site in each
primary quality assurance organization that has less than or equal
to 5 sites and two audits at primary quality assurance organizations
with greater than 5 sites. In addition, each year, four collocated
samples from primary quality assurance organizations with less than
or equal to 5 sites and six collocated samples at primary quality
assurance organizations with greater than 5 sites must be sent to an
independent laboratory, the same laboratory as the performance
evaluation audit, for analysis.
* * * * *
    4. Calculations for Data Quality Assessment.
* * * * *
    (c) At low concentrations, agreement between the measurements of
collocated samplers, expressed as relative percent difference or
percent difference, may be relatively poor. For this reason,
collocated measurement pairs are selected for use in the precision
and bias calculations only when both measurements are equal to or
above the following limits:
    (1) TSP: 20 [mu]g/m3.
    (2) Pb: 0.02 [mu]g/m3.
    (3) PM10 (Hi-Vol): 15 [mu]g/m3.
    (4) PM10 (Lo-Vol): 3 [mu]g/m3.
    (5) PM10-2.5 and PM2.5: 3 [mu]g/
m3.
* * * * *
    4.4 Statistics for the Assessment of Pb.
    4.4.1 Precision Estimate. Follow the same procedures as
described for PM10 in section 4.2.1 of this appendix
using the data from the collocated instruments. The data pair would
only be considered valid if both concentrations are greater than the
minimum values specified in section 4(c) of this appendix.
    4.4.2 Bias Estimate. For the Pb analysis audits described in
section <IP_ADDRESS> and the Pb Performance Evaluation Program described
in section <IP_ADDRESS>, follow the same procedure as described in
section 4.1.3 for the bias estimate.
    4.4.3 Flow rate calculations. For the one point flow rate
verifications, follow the same procedures as described for
PM10 in section 4.2.2; for the flow rate audits, follow
the

same procedures as described in section 4.2.3.
* * * * *

            Table A-2 of Appendix A to Part 58--Minimum Data Assessment Requirements for SLAMS Sites
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                                                                                Parameters
             Method                Assessment method       Coverage       Minimum  frequency       reported
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                                                Automated Methods
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1-Point QC for SO2, NO2, O3, CO.  Response check at   Each analyzer.....  Once per 2 weeks..  Audit
                                   concentration                                               concentration \1\
                                   0.01-0.1 ppm SO2,                                           and measured
                                   NO2, O3, and 1-10                                           concentration
                                   ppm CO.                                                     \2\.
Annual performance evaluation     See section 3.2.2   Each analyzer.....  Once per year.....  Audit
 for SO2, NO2, O3, CO.             of this appendix.                                           concentration \1\
                                                                                and measured
                                                                                concentration \2\
                                                                                for each level.
Flow rate verification PM10,      Check of sampler    Each sampler......  Once every month..  Audit flow rate
 PM2.5, PM10	2.5.                  flow rate.                                                  and measured flow
                                                                                rate indicated by
                                                                                the sampler.
Semi-annual flow rate audit       Check of sampler    Each sampler......  Once every 6        Audit flow rate
 PM10, PM2.5, PM10	2.5.            flow rate using                         months.             and measured flow
                                   independent                                                 rate indicated by
                                   standard.                                                   the sampler.