review potential PM2.5 exceptional events influencing
compliance with the revised primary annual PM2.5 NAAQS from
2010 to 2012, to notify the EPA by flagging the relevant data and
providing an initial description in AQS, and to submit documentation to
support claims for exceptional events. These schedule revisions will
also allow the EPA to fully consider and act on the submitted
information during the initial area designation process.
    If an air agency intends the EPA to consider in the revised primary
annual PM2.5 designations decisions whether PM2.5
data collected during 2013 influence compliance with the primary annual
PM2.5 NAAQS, then the air agency must flag these data by the
generic Exceptional Event Rule deadline of July 1, 2014. The EPA is
finalizing August 1, 2014, as the deadline for submitting documentation
to justify PM2.5-related exceptional events occurring in
2013 and potentially influencing compliance with the revised primary
annual PM2.5 NAAQS. The EPA believes that these deadlines
provide air agencies with adequate time to review and identify
potential exceptional events that occur in calendar year 2013 and for
the EPA to fully consider and act on the submitted information during
the initial area designation process.
    While the EPA will make every effort to designate areas for the
primary annual PM2.5 NAAQS on a 2 year schedule, the EPA
recognizes that it may need up to an additional year for the
designations process to ensure that states/tribes and the EPA base
designations decisions on complete and sufficient information. If the
EPA announces at a later date that it is extending the designations
schedule beyond 2 years based on unavailability of data, the EPA will
consider extending the 2013 exceptional event documentation submission
schedule by promulgating additional revisions to 40 CFR 50.14.
    Therefore, using the authority provided in CAA section 319(b)(2)
and in the Exceptional Events Rule at 40 CFR 50.14 (c)(2)(vi), the EPA
is finalizing the schedule for data flagging and submission of
demonstrations for PM2.5 exceptional events data potentially
influencing compliance with the revised primary annual PM2.5
NAAQS considered for initial area designations under the promulgated
primary annual PM2.5 NAAQS as presented in Table 3.

  Table 3--Revised Schedule for Exceptional Event Flagging and Documentation Submission for Data to be Used in
                               Initial Area Designations for the 2012 PM2.5 NAAQS
----------------------------------------------------------------------------------------------------------------
                                      Air quality data          Event flagging &
NAAQS Pollutant/standard/(level)/  collected for calendar     initial description       Detailed documentation
        promulgation date                   year                    deadline             submission deadline
----------------------------------------------------------------------------------------------------------------
PM2.5/Primary Annual Standard     2010 and 2011...........  July 1, 2013...........  December 12, 2013.
 (12.0 [mu]g/m\3\) Promulgated
 December 14, 2012.
                                  2012....................  July 1, 2013\a\........  December 12, 2013.
                                  2013....................  July 1, 2014\a\........  August 1, 2014.
----------------------------------------------------------------------------------------------------------------
\a\ This date is the same as the general schedule in 40 CFR 50.14.
Note: The table of revised deadlines only applies to data the EPA will use to establish the initial area
  designations for the revised primary annual PM2.5 NAAQS. The general schedule applies for all other purposes,
  most notably, for data used by the EPA for redesignations to attainment.

C. Updates for Data Handling Procedures for Reporting the Air Quality
Index

    There were no comments regarding the proposed updates for data
handling procedures for reporting the AQI. However, two table footnotes
that were part of the existing rule were inadvertently omitted from the
proposal. The inadvertently dropped footnotes were footnotes 3 and 4 of
Table 2 (``Breakpoints for the AQI'') of appendix G (``Uniform Air
Quality Index (AQI) and Daily Reporting'') to Part 58. Since the
footnotes are still applicable, the EPA has included them in the final
rule. The final rule also codifies all changes identified in the EPA
proposal regarding data handling procedures for the AQI.

VIII. Amendments to Ambient Monitoring and Reporting Requirements

    The EPA is finalizing a number of changes to the ambient air
monitoring, reporting, and network design requirements associated with
the PM NAAQS. Ambient PM monitoring data are used to meet a variety of
monitoring objectives including determining whether an area is in
violation of the PM NAAQS. Ambient PM monitoring data are collected by
state, local, and tribal monitoring agencies (``monitoring agencies'')
in accordance with the monitoring requirements contained in 40 CFR
parts 50, 53, and 58. This section discusses the monitoring changes
that the EPA is finalizing to support the revised PM NAAQS summarized
in sections III.F, IV.F, and VI.F above.
    The monitoring changes being finalized primarily relate to the
revised primary PM2.5 NAAQS. Several monitoring changes were
proposed specifically in support of a potential distinct secondary
PM2.5 visibility index standard; however, as explained in
Section VI, EPA is not finalizing a distinct secondary standard using a
visibility index and therefore is not finalizing the monitoring changes
that would have been necessary to support it. The EPA did not propose
any monitoring changes associated with the

PM10 NAAQS and is not adopting any in this final rule.

A. Issues Related to 40 CFR Part 53 (Reference and Equivalent Methods)

    To be used in a determination of compliance with the PM NAAQS, PM
data are typically collected using samplers or monitors employing an
FRM or FEM. The EPA also allows use of alternative methods where
explicitly stated in the monitoring methodology requirements (appendix
C of 40 CFR part 58), such as PM2.5 ARMs which can be used
to determine compliance with the NAAQS. The EPA prescribes testing and
approval criteria for FRM and FEM methods in 40 CFR part 53.
1. PM2.5 and PM10-2.5 Federal Equivalent Methods
    As described in the proposal, the EPA continues to believe that an
effective PM2.5 monitoring strategy includes the use of both
filter-based FRM samplers and well-performing continuous
PM2.5 monitors. Well-performing continuous PM2.5
monitors would include both non-designated continuous PM2.5
monitors and designated Class III \214\ continuous FEMs that meet the
performance criteria described in table C-4 of 40 CFR part 53 when
comparing to a collocated FRM operated by the monitoring agency. Only
designated methods (i.e., FRMs, FEMs, and ARMs) are approved to be used
in comparison to the NAAQS; however, non-designated methods may be
useful to meet other monitoring objectives (e.g., reporting the AQI).
The use of Class III continuous FEMs at SLAMS is described in more
detail in section VIII.B.3.b.ii below. Monitoring agencies are
encouraged to evaluate the quality of data being generated by FEMs and,
where appropriate, to reduce the use of manual, filter-based samplers
to improve operational efficiency and to lower overall operating costs.
To encourage such a strategy, the EPA is working with numerous
stakeholders including the monitoring committee of NACAA, instrument
manufacturers, and monitoring agencies to support national data
analyses of continuous PM2.5 FEM performance, and where such
performance does not meet data quality objectives, to develop and
institute a program of best practices to improve the quality and
consistency of resulting data.
---------------------------------------------------------------------------

    \214\ Class III refers to those methods for PM2.5 or
PM10-2.5 that are employed to provide PM2.5 or
PM10-2.5 ambient air measurements representative of one-
hour or less integrated PM2.5 or PM10-2.5
concentrations, as well as 24-hour measurements determined as, or
equivalent to, the mean of 24 one-hour consecutive measurements.
---------------------------------------------------------------------------

    The EPA believes that progress is being made to implement well
performing PM2.5 continuous FEMs across the nation. As noted
in the proposal, the first few steps involved the EPA developing and
approving the testing and performance criteria which were finalized in
2006, followed by instrument companies performing field testing and
submitting applications to the EPA, and the EPA review and approval, as
appropriate, of Class III FEMs. In the current step, monitoring
agencies are testing and assessing the data comparability from
continuous PM2.5 FEMs.
    While EPA did not propose any changes to the performance or testing
criteria in 40 CFR part 53 used to approve PM2.5 continuous
FEMs, the EPA did propose an administrative change to part 53.9--
``Conditions of designations.'' See 77 FR 39006. This section describes
a number of conditions that must be met by a manufacturer as a
condition of maintaining designation of an FRM or FEM. Subsection (c)
of this section reads, ``Any analyzer, PM10 sampler,
PM2.5 sampler, or PM10-2.5 sampler offered for
sale as part of a FRM or FEM shall function within the limits of the
performance specifications referred to in 40 CFR 53.20(a), 53.30(a),
53.50, or 53.60, as applicable, for at least 1 year after delivery and
acceptance when maintained and operated in accordance with the manual
referred to in 40 CFR 53.4(b)(3).'' The EPA's intent in this
requirement is to ensure that monitoring methods work within
performance criteria, which includes methods for PM2.5 and
PM10-2.5; however, there was no specific reference to
performance criteria for Class II \215\ and III PM2.5 and
PM10-2.5 methods. The EPA proposed to link the performance
criteria referred to in 40 CFR part 53.35 associated with Class II and
III PM2.5 and PM10-2.5 methods with this
requirement for maintaining designation of approved FEMs. The specific
performance criteria identified in 40 CFR 53.35 for PM2.5
and PM10-2.5 methods are available in table C-4 to subpart C
of 40 CFR part 53.
---------------------------------------------------------------------------

    \215\ Class II refers to those methods for PM2.5 or
PM10-2.5 in which integrated samples are taken by
filtration and subjected to a subsequent filter conditioning process
followed by a gravimetric mass determination, but which is not a
Class I equivalent methods because of substantial deviations from
the design specification of the sampler specified for reference
methods in appendix L or O (as applicable) of part 50 of the CFR.
---------------------------------------------------------------------------

    All comments received on this proposed change were supportive and
EPA is finalizing this change. The implication of this change is that
instrument manufacturers and air agencies operating the equipment will
have a shared responsibility for approved FEMs to meet required
performance criteria for at least the first 12 months of operation,
which is the typical warranty period for an instrument. By having a
shared responsibility for an FEM to meet the performance criteria,
instrument companies and air agencies will both be motivated to ensure
the best practices for installing, operating, and servicing an
instrument are carried out according to the instrument company's
operating manual and other readily available materials \216\ in support
of each method.
---------------------------------------------------------------------------

    \216\ At the recent National Air Quality Conference in May of
2012, a training session on ``Best Practices for Operating
PM2.5 Continuous FEMs'' was conducted. Presentations from
this session are publically available on EPA's web site at: http://www.epa.gov/ttn/amtic/2012present.html.
---------------------------------------------------------------------------

2. Use of Chemical Speciation Network (CSN) Methods To Support the
Proposed New Secondary PM2.5 Visibility Index NAAQS
    The EPA had proposed to use CSN methods to support the proposed new
secondary PM2.5 visibility index NAAQS; however, as
explained in Section VI of this final rule, EPA is not finalizing the
new secondary PM2.5 visibility index NAAQS and therefore has
no need to finalize the CSN methods to support such a standard.
    Despite our decision not to finalize formal requirements for CSN
methods, this network remains a critical component in our PM monitoring
program. The EPA, monitoring agencies, and external scientists and
policy makers use PM2.5 data from the CSN to support several
important monitoring objectives such as: Development of modeling tools
and the application of source apportionment modeling for control
strategy development to implement the NAAQS; health effects and
exposure research studies; assessment of the effectiveness of emission
reductions strategies through the characterization of air quality; and
development of SIPs. The use of the CSN to support all of these
objectives will continue.

B. Changes to 40 CFR Part 58 (Ambient Air Quality Surveillance)

1. Terminology Changes
    The EPA proposed to revise several terms associated with
PM2.5 monitor placement to ensure consistency with other
NAAQS and to conform with long-standing practices in siting of
equipment by monitoring agencies (77 FR 39007).
    The EPA proposed to revoke the term ``community-oriented'' and
replace it

with the term ``area-wide.'' The term ``community-oriented,'' while
used within the description of the design criteria for
PM2.5, is not defined and has not been used in the design
criteria for other NAAQS pollutants. Appendix D to 40 CFR part 58
presents a functional usage of the term where sites at the neighborhood
and urban scale area are considered to be ``community-oriented.'' In
addition, population-oriented, micro-or middle-scale PM2.5
monitoring may also be considered ``community-oriented'' when
determined by the Regional Administrator to represent many such
locations throughout a metropolitan area. The EPA proposed to replace
this usage of ``community-oriented'' with the term ``area-wide'' in the
text of the PM2.5 network design criteria and to define it
in 40 CFR 58.1 to provide a more consistent usage of this concept
throughout appendix D of 40 CFR part 58. Specifically, the EPA proposed
that the terminology would read--``Area-wide means all monitors sited
at neighborhood, urban, and regional scales, as well as those monitors
sited at either micro-or middle-scale that are representative of many
such locations in the same CBSA.''
    The EPA proposed to revoke the term ``Community Monitoring Zone''
(CMZ) and to remove references to it in 40 CFR part 58. Community
monitoring zone is currently defined as ``an optional averaging area
with established, well defined boundaries, such as county or census
block, within an MPA \217\ that has relatively uniform concentrations
of annual PM2.5 as defined by appendix N of 40 CFR part 50
of this chapter. Two or more community oriented state and local air
monitoring stations (SLAMS) monitors within a CMZ that meet certain
requirements as set forth in appendix N of 40 CFR part 50 may be
averaged for making comparisons to the annual PM2.5 NAAQS.''
The EPA proposed to revoke this term and references to it since, as
discussed in section VII.A.2 above, the EPA proposed to eliminate all
references to the now-revoked spatial averaging option throughout
appendix N.
---------------------------------------------------------------------------

    \217\ Monitoring Planning Area (MPA) means a contiguous
geographic area with well established, well defined boundaries, such
as a CBSA, county or State, having a common areas that is used for
planning monitoring locations for PM2.5.
---------------------------------------------------------------------------

    The one comment directly addressing the proposed rule changes (from
a state air agency) supported the proposal. A few industry commenters
noted the change in the context of how monitoring data are used to
compare to the NAAQS, but did not address the proposed specific
terminology changes. However, as explained in section III.E.3.a,
several industry commenters did provide comments critical of EPA's
proposal to revoke spatial averaging which is related to revoking the
term ``Community Monitoring Zone''.
    For the reasons explained above, the EPA is finalizing its proposed
change to revoke the term ``community-oriented'' and to replace it with
the term ``area-wide.'' The EPA is also finalizing its proposal to
revoke the term ``Community Monitoring Zone'' (CMZ) and references to
it in 40 CFR part 58.
2. Special Considerations for Comparability of PM2.5 Ambient
Air Monitoring Data to the NAAQS
    In general, ambient monitors must meet a basic set of requirements
before the resulting data can be used for comparison to the NAAQS.
These requirements include the presence and implementation of an
approved quality assurance project plan; the use of methods that are
reference, equivalent, or other approved method as described in
appendix C to 40 CFR part 58; and compliance with the probe and siting
path criteria as described in appendix E to 40 CFR part 58. While these
40 CFR part 58 requirements apply to any monitor that provides data for
comparison to the NAAQS, there are certain additional restrictions that
apply only to PM2.5 monitoring.\218\ These additional
restrictions provide that sites must be ``population-oriented'' for
comparison to either the 24-hour or annual NAAQS, and specifically for
comparison to the annual NAAQS, sites must be sited to represent area-
wide locations. There is a related provision that provides for
comparing sites at micro- or middle-scales to the annual
PM2.5 NAAQS when the site is determined by the Regional
Administrator to represent a larger region of localized high ambient
PM2.5 concentration.
---------------------------------------------------------------------------

    \218\ These are found in 40 CFR 58.30 (Special considerations
for data comparisons to the NAAQS).
---------------------------------------------------------------------------

    These provisions have been in the monitoring regulations since the
inception of the PM2.5 NAAQS. Nonetheless, these provisions
and the fact that such monitoring requirements are not found in the
requirements for all other criteria pollutants have created areas of
uncertainty for the EPA and state, local, and tribal agencies that base
implementation decisions on monitoring requirements through programs
such as dispersion modeling, SIP planning, and the calculation of
transportation conformity budgets. For example, in developing modeling
guidance to support near-road transportation conformity modeling, the
EPA struggled to determine how the identification of acceptable
PM2.5 receptor locations can be reconciled with the
PM2.5 monitoring regulations that reference potentially
acceptable (or unacceptable) monitoring locations that may, or may not,
be considered unique for purposes of comparing to the annual
PM2.5 NAAQS. Accordingly, the EPA proposed to revise these
particular PM2.5 requirements for consistency with long-
standing practices in all other NAAQS pollutant monitoring networks,
and to ensure that interpretation of the monitoring rules does not
cause ambiguity in implementation examples that also include the
treatment of unmonitored areas (see 77 FR 39007-009). Each of these
topics is described below.
a. Eliminating the Term ``Population Oriented'' From Section 58.30
    The EPA proposed to remove the term ``population oriented'' from
section 58.30 so that there would no longer be an explicit requirement
that PM2.5 monitoring sites be ``population-oriented'' for
comparison to the PM2.5 NAAQS. The EPA noted that this
requirement is not entirely consistent with the definition of
``ambient'' used in the NAAQS. The EPA's definition of ambient air is
specified in 40 CFR 50.1--``Ambient air means that portion of the
atmosphere, external to buildings, to which the general public has
access.'' The EPA's definition of ``population-oriented'' is provided
in 40 CFR 58.1--``Population-oriented monitoring (or sites) means
residential areas, commercial areas, recreational areas, industrial
areas where workers from more than one company are located, and other
areas where a substantial number of people may spend a significant
fraction of their day.'' The NAAQS are standards for concentrations
``in the ambient air'' \219\--i.e., air to which members of the public
could be exposed-- and all monitors used for NAAQS regulatory purposes
must be representative of ambient air concentrations.\220\ Consistent
with this requirement and the long-standing practice of monitoring
agencies locating ambient monitors, the EPA's experience is that
PM2.5 monitors are placed in areas that are representative
of population exposures. There are no PM2.5 monitors
currently operating as

``non-population oriented'' and the EPA does not believe that the
requirement for near-road monitoring (discussed in detail further
below) will result in monitors that are not representative of
population exposures. At the same time, the specification that certain
PM2.5 monitors must be ``population-oriented'' in the rules
has created substantial confusion in how to treat potential locations
of exposure for NAAQS-related regulatory requirements other than
monitoring network design, such as in applying modeling as part of a
PSD or SIP exercise.\221\
---------------------------------------------------------------------------

    \219\ See 40 CFR part 50.
    \220\ See, e.g., 40 CFR 58.1 (defining ``federal reference
method'' as ``a method for sampling and analyzing the ambient air
for an air pollutant * * *'')
    \221\ Examples include dispersion modeling to support NAAQS
attainment planning, associated SIP development, and the calculation
of transportation conformity budgets.
---------------------------------------------------------------------------

    The EPA's intention in proposing to remove the term ``population
oriented'' from section 58.30 was to remove a potential source of
inconsistency in the monitoring rules as they apply for all the NAAQS.
As noted earlier, the NAAQS provide protection for the public health
and welfare in areas where the public can be exposed. For all other
criteria pollutants, the monitoring requirements have no such
restriction on the comparability of a monitor. In the case of
PM2.5 however, the additional restriction of monitors being
required to be ``population-oriented'' for comparability to the NAAQS
has existed. The term ``population oriented'' has lacked a quantitative
definition (e.g., the interpretation of ``substantial number'' in the
definition of ``population-oriented''), therefore monitoring agencies
and those stakeholders who based implementation strategies and
decisions on monitoring regulations have been uncertain about which
locations would meet requirements described in Sec.  58.30, which do
not exist for any other NAAQS. Monitoring agencies are also not in a
position to precisely forecast where future residential, commercial, or
recreational development may occur, therefore requiring that
PM2.5 monitors that are to be compared to the NAAQS can only
be located where ``substantial numbers of people'' live, work, or play
(i.e., in the present tense) represents an unwise limitation on the
flexibility of monitoring agencies to revise their PM2.5
networks to account for anticipated changes in demographics or
development as well as a contradiction with the inherent applicability
of the NAAQS in ambient air locations where the public has access
(e.g., in any location outside the perimeter of a industrial facility).
From an operational standpoint, we note that revoking this term would
not change the requirements in the PM2.5 network design
criteria. To the extent that the phrase ``population-oriented'' served
to emphasize the need for micro- or middle-scale monitors to be
representative of locations with population exposure to be comparable
to the annual NAAQS, the definition of ambient air, together with the
requirement in revised section 58.30 that such sites must be ``area-
wide'' to be comparable to the annual NAAQS, adequately serves the same
purpose. By revising the PM2.5 monitoring rules to ensure
consistency with the long-standing definition of ambient air applied to
the other NAAQS pollutants, the EPA will be able to more clearly define
how to treat potential exposure receptors for other NAAQS regulatory
requirements, regardless of whether monitoring exists or not.
    Public comments on this issue were supported by air agencies and
public health and environmental groups. Two commenters from state
agencies supported the proposed change, with one noting further that
regardless of a change it is still the air agency's responsibility to
plan a network with sites that are appropriate for comparison to the
NAAQS. Several public health and environmental groups supported
revoking ``population oriented'' as a condition for comparability of
PM2.5 monitoring sites to the NAAQS stating that retaining
such a policy is inconsistent with the text, purpose and intent of the
Clean Air Act. Most industry commenters did not support revoking
``population-oriented'' as a condition for comparison to the NAAQS.
Most of these comments raised concerns with using data from an area
where potentially no one is exposed.
    In considering these comments, the EPA agrees that it is
appropriate for individual air agencies to provide a recommendation in
the annual monitoring network plan regarding whether any site may or
may not be appropriate for comparison to the PM2.5 (or any)
NAAQS. The roles of the air agency and the EPA in this process of
identifying whether a site is, or is not, consistent with the network
plan requirements for a NAAQS are specified in the already-established
monitoring requirements of Sec.  58.10. In this approval process, the
air agency initiates the recommendations and the EPA has the
responsibility to approve, as appropriate, any plans that provide for
changes to the network.
    EPA disagrees with the industry comments. As noted above, monitors
(including those for PM2.5) must already meet the test of
being representative of ambient air to be compared to the NAAQS, and
thus such monitors meeting this test will be sited in locations where
people are already located, or where they could be exposed, whether or
not the term ``population oriented'' appears in section 58.30.
Moreover, as discussed below, comparisons to the annual
PM2.5 NAAQS can be only be from monitors ``that are
representative of area-wide air quality.'' ``Area-wide'' monitors are
those at the neighborhood scale or larger, or at smaller scales if they
are representative of many such locations in the same CBSA. The EPA
anticipates that a monitor that is sited as representative of ambient
air at the neighborhood scale or larger (or of ambient air at many
smaller areas) will be representative of population exposure. This
conclusion is further supported by the fact that all current monitors
used for comparison with the PM2.5 NAAQS are designated as
``population-oriented.'' \222\
---------------------------------------------------------------------------

    \222\ The last known non population-oriented site at Sun Metro
in El Paso Texas (AQS ID: 48-141-0053), was shut down in October
2010 and is in the process of being moved to a nearby neighborhood.
---------------------------------------------------------------------------

    After consideration of the public comments, the EPA is finalizing
its decision to revoke use of ``population-oriented'' as a condition
for comparability of PM2.5 monitoring sites to the NAAQS.
The EPA concludes that the ``population-oriented'' language is
unnecessary and inconsistent with other monitoring rules, and should
therefore be removed.
b. Applicability of Micro- and Middle-Scale Monitoring Sites to the
Annual PM2.5 NAAQS
    The EPA proposed language in 40 CFR section 58.30 to clarify when
data from PM2.5 monitoring sites at micro- and middle-scale
locations can be compared to the annual PM2.5 NAAQS. The
EPA's intent was to provide consistency and predictability in the
interpretation of the monitoring regulations. The EPA's current rules
state that ``PM2.5 data that are representative, not of
area-wide but rather, of relatively unique population-oriented micro-
scale, or localized hot spot, or unique population-oriented middle-
scale impact sites are only eligible for comparison to the 24-hour
PM2.5 NAAQS. For example, if the PM2.5 monitoring
site is adjacent to a unique dominating local PM2.5 source
or can be shown to have average 24-hour concentrations representative
of a smaller than neighborhood spatial scale, then data from a monitor
at the site would only be eligible for comparison to the 24-hour
PM2.5 NAAQS.'' We proposed clarifying language to

explicitly state that measuring PM2.5 in micro- and middle-
scale environments near emissions of mobile sources, such as a highway,
does not constitute being impacted by a ``unique'' source and so could
be compared to the annual PM2.5 NAAQS. We explained that
mobile sources are rather ubiquitous and there are many locations
throughout an urban area where elevated exposures attributable to such
sources could occur. Therefore, we proposed that in most cases the
potential location for a PM2.5 monitoring site, including
micro- and middle-scale sites near roadways, would be eligible for
comparison to the annual NAAQS. We further noted that the existing
definition of ``middle scale'' in appendix D to part 58 already
indicates that traffic corridors can be middle scale, and hence not
unique, and therefore comparable to the annual PM2.5 NAAQS
(as well as to the 24-hour PM2.5 NAAQS) (77 FR 39008).
    Air agencies that commented on this part of the proposed rule
offered a variety of positions. One air agency stated that sites at
these smaller scales should not be compared to the annual NAAQS.
Another air agency stated that these sites should be considered for
comparison with the annual PM2.5 NAAQS only when the air
agency initiates a decision that such sites at these smaller scales are
area-wide. A different air agency offered that all micro- and middle-
scale sites should be compared to the annual NAAQS since the wording of
the provision is problematic and will be difficult for agencies to
implement.
    Industry commenters were largely against finalizing such a
provision. The major concern raised was that such a provision combined
with other related provisions represented an unwarranted tightening of
the NAAQS. Some industry commenters pointed out that there are examples
of unique locations in near road environments and as such EPA should
not presume that PM2.5 monitors in these locations should be
applicable to the annual PM2.5 NAAQS.
    In considering comments on this part of the rule, the EPA notes
that there are already examples of where the States and EPA have
determined certain micro- and middle-scale locations as applicable to
the annual NAAQS and others where they were determined as not
applicable to the annual PM2.5 NAAQS. These cases exist
where a State proposed and the Regional Administrator determined that
either the micro-scale or middle-scale site did or did not represent
many similar areas in a CBSA (40 CFR 58.30 and section 4.7 to Appendix
D, part 58). The EPA also notes that the existing descriptions of the
types of micro- and middle-scale sites which are unique and cited in
Sec.  58.30 are not being amended and that data from these types of
sites would remain as not comparable to the annual PM2.5
NAAQS. Accordingly, PM2.5 data that are representative, not
of area-wide but rather, of relatively unique population-oriented
microscale, or localized hot spots, or unique middle scale impact sites
will only be eligible for comparison to the 24-hour NAAQS. Our proposal
was to clarify language to explicitly state that measuring
PM2.5 in micro- and middle-scale environments near emissions
of mobile sources, such as a highway, does not constitute being
impacted by a ``unique'' source and so the site could be compared to
the annual PM2.5 NAAQS. However, in light of public comments
pointing out that there are cases where near-road environments can be
considered a unique location; EPA is not finalizing this part of the
rule language. Examples of such locations that are considered unique
and should therefore not be considered applicable to the annual
PM2.5 NAAQS are explained later in section VIII.B.3.b.i. As
noted in the preamble to the proposed rule (77 FR 39008-09), air
agencies and the EPA will use the annual monitoring network plan
described in 40 CFR 58.10 for identification and approval of sites that
are suitable and sites that are not suitable for comparison with the
annual PM2.5 NAAQS.
    The EPA disagrees with those comments that asserted that the
proposed change would have represented a tightening of the NAAQS. As
explained in section III.E.3.a on the form of the annual NAAQS, the EPA
carefully considered that areas such as traffic corridors were
potential high exposure areas, since a significant fraction of the
population, including at-risk populations, live in proximity to major
roads and should be afforded the degree of protection intended by the
revisions to the form and level of the annual PM2.5 standard
being adopted. Monitoring in such areas as traffic corridors does not
make the annual standard more stringent than intended, but rather
affords the populations of such middle- and micro-scale areas (where
determined to represent area-wide air quality) the requisite level of
protection from long-term exposure to PM2.5.
3. Changes to Monitoring for the National Ambient Air Monitoring System
a. Background
    As described in appendix D to 40 CFR part 58, the ambient air
monitoring networks must be designed to meet three basic monitoring
objectives:
    (a) Provide air pollution data to the general public in a timely
manner. Data can be presented to the public in a number of attractive
ways including through air quality maps, newspapers, Internet sites,
and as part of weather forecasts and public advisories.
    (b) Support compliance with ambient air quality standards and
emissions strategy development. Data from FRM, FEM, and ARM monitors
for NAAQS pollutants will be used for comparing an area's air pollution
levels against the NAAQS. Data from monitors of various types can be
used in the development of attainment and maintenance plans. SLAMS, and
especially National Core Monitoring Network (NCore) \223\ station data,
will be used to evaluate the regional air quality models used in
developing emission strategies and to track trends in air pollution
abatement control measures' impact on improving air quality. In
monitoring locations near major air pollution sources, source-oriented
monitoring data can provide insight into how well industrial sources
are controlling their pollutant emissions.
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    \223\ NCore is a multi-pollutant network that integrates several
advanced measurements for particles, gases and meteorology (U.S.
EPA, 2011a, Appendix B, section B.4). Measurements required at NCore
include PM2.5 mass and speciation, PM10-2.5
mass, ozone, CO, SO2, NO, NOy, and basic
meteorology.
---------------------------------------------------------------------------

    (c) Support for air pollution research studies. Air pollution data
from the NCore network can be used to supplement data collected by
researchers working on health effects assessments and atmospheric
processes or for monitoring methods development work.
    To support the air quality management work indicated in the three
basic air monitoring objectives, a network must be designed with a
variety of types of monitoring sites. Monitoring sites must be capable
of informing managers about many things including the peak air
pollution levels, typical levels in populated areas, air pollution
transported into and outside of a city or region, and air pollution
levels near specific sources. Following is a listing of six general
site types: (a) Sites located to determine the highest concentrations
expected to occur in the area covered by the network (highest
concentration); (b)

sites located to measure typical concentrations in areas of high
population density (population oriented); (c) sites located to
determine the impact of significant sources or source categories on air
quality (source impact or source oriented); (d) sites located to
determine general background concentration levels (general background);
and (e) sites located to determine the extent of regional pollutant
transport among populated areas (regional transport); and in support of
secondary standards (welfare related impacts).
b. Primary PM2.5 NAAQS
    The EPA proposed to add a near-road component to the
PM2.5 network design criteria and to clarify the use of
approved PM2.5 continuous FEMs at SLAMS.
ii. Addition of a Near-Road Component to the PM2.5
Monitoring Network
    The EPA proposed to add a near-road component to the
PM2.5 monitoring network (77 FR 39009). The EPA explained
that there are gradients in near-roadway PM2.5 that are most
likely to be associated with heavily travelled roads (particularly
those with significant heavy-duty diesel activity), and that the
largest numbers of impacted populations are located in the largest
CBSAs in the country (Ntziachristos et al., 2007; Ross et al., 2007;
Yanosky et al., 2009; Zwack et al., 2011). The EPA further noted that
by adding a modest number of PM2.5 monitoring sites that are
leveraged with measurements of other pollutants in the near-road
environment, a number of key monitoring objectives will be supported,
including collection of NAAQS comparable data in the near-road
environment, support for long-term health studies investigating adverse
effects on people, providing a better understanding of pollutant
gradients impacting neighborhoods that parallel major roads,
availability of data to validate performance of models simulating near-
road dispersion, characterization of areas with potentially elevated
concentrations and/or poor air quality, implementation of a multi-
pollutant paradigm as stated in the NO2 NAAQS proposed rule
(74 FR 34442, July 15, 2009), and monitoring goals consistent with
existing objectives noted in the specific design criteria for
PM2.5 described in appendix D, 4.7.1(b) to 40 CFR part 58.
    The monitoring methods that are appropriate for this purpose are an
FRM, FEM, or ARM. The EPA recognized that there are limitations in the
ability of some of these methods to accurately measure PM2.5
mass due to the incomplete retention of semi-volatile material on the
sampling medium (U.S. EPA, 2009a, section <IP_ADDRESS>). This limitation is
relevant to the near-road environment as well as to other environments
where PM is expected to have semi-volatile components. The EPA also
recognized that continuous PM2.5 FEMs, which provide mass
concentration data on an hourly basis, are better suited to accomplish
the goals of near-road monitoring as they will complement the time
resolution of the other air quality measurements and traffic data
collected at the same sites. In this regard, particular
PM2.5 FEMs are generally better suited for near-road
monitoring than FRMs. However, filter-based FRMs do offer some
advantages which may be highly desirable for near-road monitoring, such
as readily available filters for later chemical analysis such as for
elemental composition by x-ray fluorescence and black carbon (BC) by
transmissometry. As a result of these tradeoffs, monitoring agencies
are encouraged to select one or more PM2.5 methods for
deployment at near-road monitoring stations that best meet their
agencies monitoring objectives while ensuring that at least one of
those methods is appropriate for comparison to the NAAQS (i.e., a FRM,
FEM, or ARM). The EPA believes that by allowing monitoring agencies to
choose the FRM, FEM, or ARM method(s) that best fits their needs,
whether filter-based or continuous, the data will still be able to meet
the objectives cited above while ensuring maximum flexibility for the
monitoring agencies in the operation of their network.
    The EPA believes that requiring a modest network of near-road
compliance PM2.5 monitors is necessary to provide
characterization of concentrations in near-road environments including
for comparison to the NAAQS. These long-term monitors will supplement
shorter-term networks to support the tracking of long-term trends \224\
of near-road PM2.5 mass concentrations and other pollutants
in near-road environments where people are exposed. Therefore, the EPA
proposed to require near-roadway monitoring of PM2.5 at one
location within each CBSA with a population of one million persons or
greater. The EPA believes that this network will be adequate to support
the NAAQS since the largest CBSAs are likely to have greater numbers of
exposed populations, a higher likelihood of elevated near-road
PM2.5 concentrations, and a wide range of diverse situations
with regard to traffic volumes, traffic patterns, roadway designs,
terrain/topography, meteorology, climate, surrounding land use and
population characteristics. Given the latest population data available,
the proposed requirement would result in approximately 52 required
near-road PM2.5 monitors across the country. An indirect
benefit of this network design is that monitoring agencies in these
largest CBSAs are more likely to already have redundant monitors that
could be relocated to the near-road environment, reducing costs for
equipment and ongoing operation.\225\ While only a single near-road
PM2.5 monitor is required within each of the CBSAs, agencies
may elect to add additional PM2.5 monitoring sites in near-
road environments.
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    \224\ For example, the emissions used for the PM NAAQS RIA
modeling show that nationwide on-road primary PM2.5
emissions are expected to be reduced by 63% between 2007 and 2020.
Additionally, the elemental carbon portion of the on-road emissions
is expected to drop by 81 percent between 2007 and 2020. Therefore,
we expect that measured near-road PM2.5 gradients will be
much lower in the future as elemental carbon is a large fraction of
the gradient, due to future impacts of existing mobile source
controls.
    \225\ EPA Regional Administrator approval would be required
prior to the discontinuation of SLAMS monitors, based on the
criteria described in 40 CFR 58.14(c).
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    While the EPA recognized that the location of maximum concentration
of PM2.5 exposure from roadway sources might differ from the
maximum location of NO2 or other pollutants, the EPA
proposed to require that near-road PM2.5 monitors be
collocated with the planned NO2 monitors. The NO2
network design considers multiple factors that are also relevant for
PM2.5 concentrations (i.e., average annual daily traffic,
fleet mix, roadway design, congestion patterns, terrain, and
meteorology) and significant thought and review has already gone into
its design, including pilot studies at five locations, and the
development of a technical assistance document in conjunction with the
affected monitoring agencies and the CASAC AAMMS (Russell and Samet,
2010b) to support deployment. Further, this collocation will allow
multiple pollutants to be tracked in the near-road environment. To the
extent that air agencies are still determining the optimum location for
their multi-pollutant \226\ near-road monitoring stations, EPA
encourages consideration of sites that best reflect measurement of
maximum concentrations associated with exposure of people living in
areas

that parallel major roads, to maximize the value of the data for use
later in health studies. Therefore, while compromises may be necessary
when siting a multi-pollutant near road monitoring station, on balance,
the EPA believes this is the most efficient and beneficial approach for
deployment of this component of the network.
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    \226\ NO2, CO, and now PM2.5 measurements
are all expected to be collocated at near-road monitoring stations.
---------------------------------------------------------------------------

    The EPA notes that the planned 52 near-road monitors represent a
small number of the total approximate 900 operating PM2.5
monitoring stations across the country. The EPA could have proposed
more near-road sites, however, the addition of sites in lower
population CBSAs is not expected to lead to much if any difference in
characterization of air quality since the bump in PM2.5
concentration associated with near-road environments in lower
population CBSAs, which typically have correspondingly less travelled
roads, is expected to be very small. The EPA could also have proposed
multiple sites in larger CBSAs; however, State monitoring programs are
already working towards representative near-road monitoring stations
and there is a synergistic value in ensuring these measurements are
collocated with multiple other measurements to serve the monitoring
objectives noted above. Since EPA has already finalized requirement of
CO monitoring at near-road stations in CBSA's with a population of 1
million or more at sites that are collocated with NO2, there
would be less value in requiring any more than 52 PM2.5
monitors as any more stations will not have CO for use in multi-
pollutant monitoring objectives (e.g., health studies and model
evaluation).
    Ideally, near-road sites would be located at the elevation and
distance from the road where maximum PM2.5 levels occur in
this environment, representing locations where populations are exposed;
for example, in apartments and other housing; schools located along
major roadways; industrial parks where workers exposed; and in
recreational areas such as greenways, bikeways, and other park
facilities that are often developed along roads. Specific to probe and
siting criteria for near-road PM2.5 monitors, which is
explained later in this section, EPA did not set additional criteria on
what the elevation and distance requirements should be, beyond what is
already defined for PM2.5 or near-road NO2
monitors for reasons explained above. Also, the EPA did not propose
that the near-road PM2.5 monitors be located within a
specific distance of other area-wide sites; however, monitoring
agencies are encouraged to consider that a near-road site selected in
accordance with monitoring requirements and also located in proximity
to a robust area-wide site, such as an NCore station, would provide
useful information in characterizing the near-road contribution to
multiple pollutants, including PM2.5 and tracking the
decreasing trend that is expected in the PM2.5 near-road
gradient over time, due to future impacts of existing mobile source
controls.
    The timeline to implement the near-road PM2.5 monitors
should be as minimally disruptive to on-going operations of monitoring
agency programs as possible recognizing monitoring agency resource
constraints, while still meeting the need to collect for near-road
PM2.5 data in a timely fashion. Since the near-road
PM2.5 monitors were proposed to be collocated with the
emerging near-road NO2 network that was scheduled to be
operational by January 1, 2013,\227\ the EPA believes it is appropriate
to wait until after the near-road NO2 network is established
before implementing the near-road PM2.5 monitors. Therefore,
the EPA proposed that each PM2.5 monitor planned for
collocation with a near-road NO2 monitoring site be
implemented no later than January 1, 2015.
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    \227\ The EPA has proposed a revised timeline for deployment of
the near-road NO2 monitors, where all CBSAs with one
million or more people are to have their first near-road
NO2 station operational by January 1, 2014 (77 FR 64244,
October 19, 2012).
---------------------------------------------------------------------------

    The EPA received comments from a number of air agencies, industrial
groups, and environmental and public health organizations on its
proposal to require PM2.5 monitoring in near-road
environments.
    Among comments from air agencies, several commenters did not
support the addition of near road monitoring citing the challenges of
siting these stations and the additional cost it would require to
operate the monitors. Several air agencies recognized the value of
adding monitors to provide better characterization of exposures in
near-road environments, but recommended a slower deployment of the
PM2.5 monitors so that it can be phased in over a multi-year
period. Several air agencies recommended that the PM2.5
monitoring in the near-road environment be deployed on a phased-in
schedule with the first such monitors being required no sooner than one
year after deployment of the NO2 sites. These air agencies
stated that phasing in of the PM2.5 monitors in the near
road environment would allow more time to learn and share information
on what worked best in deploying the NO2 monitors at near-
road monitoring stations, since NO2 is the first pollutant
required to be monitored at near-road stations. A few air agencies
identified a need to more clearly support or require the maintenance of
as much of the existing network of neighborhood scale PM2.5
monitoring sites as possible in regulatory text. These neighborhood
scale PM2.5 sites were identified by commenters as the most
broadly representative sites for characterizing CBSA wide exposures
that are supportive of a number of monitoring objectives. A few air
agencies also identified a need for flexibility in the proposed network
design requirement that PM2.5 near-road monitors must be
collocated with the NO2 monitors in the near-road
environment. The commenters suggested allowing flexibility for air
agencies to meet the requirement for PM2.5 in a near-road
environment by siting at a different near-road location where
PM2.5 concentrations are expected to be high.
    Most industry commenters did not support the addition of near-road
monitoring for PM2.5, again arguing that using data from
such monitors, for comparison to the NAAQS, combined with other changes
(i.e., elimination of ``population-oriented'' as a criteria for
comparison to the NAAQS and the elimination of spatial averaging) would
represent, in their judgement, a tightening of the PM2.5
NAAQS. A few of these commenters asserted that monitoring in the near-
road environment is not representative of ambient air exposures. A few
industry comments noted that if the EPA required PM2.5
monitoring in the near-road environment, any data collected should not
be used for comparison to the NAAQS. One commenter stated it had no
problem with monitoring in the near-road environment, so long as any
such monitoring used to compare to the PM2.5 annual NAAQS is
population-oriented. One commenter stated that the decision to co-
locate with NO2 monitors was based on convenience and the
intent of the NO2 near-road monitoring is to find the
highest micro-scale concentrations within a few meters of the most
heavily travelled expressways, representing a unique situation.
    Environmental and public health groups strongly support the
addition of PM2.5 monitoring to the near-road environment.
Commenters cited the large number of people that live in proximity to
major roadways \228\ in their

support for adding these monitors, that such protection of people in
these environments is long overdue, and that such data therefore be
used for comparison to the NAAQS.
---------------------------------------------------------------------------

    \228\ One study identified that 45 million Americans live within
300 feet of a major roadway or other source of mobile emissions. The
commenters' information is based on the American Housing Survey,
which is available on the Web at: http://www.census.gov/housing/ahs/data/ahs2009.html. The survey provides an estimate of the county's
housing units in the U.S. that are located with 300 feet of a
highway with four or more lanes, or a railroad, or an airport.
---------------------------------------------------------------------------

    Regarding comments from air agencies that the near-road monitors
are challenging to site and that there is additional cost in operating
these monitors, the EPA maintains that the major challenges in siting
would already be accomplished by implementing the required
NO2 monitoring stations in near-road environments since the
EPA fully expects that the PM2.5 monitors will be placed at
the NO2 near roadway stations and has revised the
PM2.5 monitoring requirements consistent with that
expectation. The EPA also points out that the requirements for the
minimum number of PM2.5 monitors is unchanged and that in
most cases the addition of near-road PM2.5 monitors can be
accomplished by relocating an existing monitor, with no net increase in
monitors. Thus, while we are requiring a new component of the
PM2.5 monitoring network, the overall size of the network is
expected to remain about the same, and we expect that air agencies can
meet this requirement by relocating existing lower-priority monitors.
In considering comments from air agencies on a schedule for
implementing PM2.5 monitors at near road monitoring
stations, the EPA is persuaded by commenters from air agencies who
stated that a phased deployment of the PM2.5 monitors would
be a better approach as it would allow agencies to learn from the
deployment of the NO2 monitors and a first phase of
PM2.5 monitors. Phasing in the deployment of monitors is
also consistent with previous CASAC advice (Russell and Samet, 2010b)
on a schedule for deployment of near-road NO2 monitors.
    Regarding comments from air agencies on maintaining the
neighborhood scale monitoring stations as the largest part of the
network as these sites are the most broadly representative of exposures
across CBSAs, the EPA supports such a goal. Neighborhood scale
monitoring sites remain the backbone of the PM2.5 monitoring
network and they will continue to represent over two thirds of the
operating network following the deployment of the near-road monitors.
The EPA expects that each CBSA required to monitor for PM2.5
will maintain its existing highest concentration area-wide monitoring
site (referred to as the design value site) and not attempt to move
such sites to near-road environments. Maintaining the area-wide and
largely neighborhood scale design value sites is critical to the long-
standing goal of using data to support a variety of monitoring
objectives. The EPA also recognizes that while every PM2.5
monitor has value in some capacity at its current location, air
agencies are expected to recommend relocation of monitors that are
relatively low in priority to meet the near-road requirement.
    Regarding comments from air agencies on the need for flexibility in
the network design requirement that PM2.5 near-road monitors
must be collocated with the NO2 monitors in the near-road
environment, the EPA points out that it prefers to maintain this
requirement so that the multi-pollutant data are available to support
the monitoring objectives cited above. However, the EPA also recognizes
there may be cases where an air agency recommends siting their near-
road PM2.5 monitor in another high concentration near-road
environment. The EPA believes such cases will be very limited, but that
these situations can be supported in one of two ways. First, EPA and
the air agency can use their discretion to site two near-road
PM2.5 monitors in the area. Second, the EPA can use its
discretion in approving a deviation from the PM2.5
monitoring requirements as already exists in the network design
criteria. Such deviations are to be approved by the Regional
Administrator as described in section 4.7.1 of Appendix D to part 58.
    Regarding the comment that PM2.5 monitors in near-road
environments were sited for convenience, which due to siting with
NO2 monitors a few meters from the road presents a unique
situation, the EPA disagrees that these monitors were sited solely for
convenience or that they would represent a unique situation within an
urban area. On the initial point, the EPA believes that the
characterization of representative maximum PM2.5
concentrations due to on-road mobile sources and the appropriate
location of such PM2.5 monitors will be the same approximate
locations that are the focus of the near-road NO2 network.
This is due to the fact that PM2.5, like NOX, is
disproportionately influenced by heavy duty (HD) vehicles which are
predominantly diesel fueled, when compared to light duty (LD) vehicles
which are primarily gasoline fueled. Specifically, for both
PM2.5 and NOX, HD vehicles emit more of these two
pollutants and their precursors on a per vehicle basis than LD
vehicles. The EPA recognized this fact in the near-road NO2
network by requiring states to consider the fleet mix of candidate road
segments where near-road monitoring might occur. In the design of the
NO2 near-road network where the PM2.5 monitors
will be installed, states were instructed to place a higher priority on
those highly trafficked roads which have more diesel fueled vehicles
using a metric called the fleet equivalent average annual daily
traffic.\229\ As such, the Agency believes it is appropriate that
required near-road PM2.5 monitors would be located with
near-road NO2 monitors as they are similarly influenced not
only by fleet mix but also by total traffic count, congestion patterns,
roadway design, terrain, and meteorology. On the second point with
regard to such sites representing a unique situation within an urban
area, EPA points out that the determination of a near-road micro- or
middle-scale site being considered to represent ``area-wide'' air
quality or ``unique'' will be made on a case by case basis with the
monitoring agency providing such recommendations in their annual
monitoring network plans described in Sec.  58.10. Examples of such
``unique'' micro- and middle-scale locations are provided later in this
section.
---------------------------------------------------------------------------

    \229\ See the Near-road NO2 Monitoring Technical
Assistance Document at: http://www.epa.gov/ttn/amtic/files/nearroad/NearRoadTAD.pdf.
---------------------------------------------------------------------------

    We do not accept the comment that siting some monitors in near
roadway environments makes the standard impermissibly more stringent. A
significant fraction of the population lives in proximity to major
roads. These exposures occur in locations that represent ambient air
for which the agency has a responsibility to ensure the public is
protected with an adequate margin of safety. Ignoring monitoring
results from such areas (or not monitoring at all) would abdicate this
responsibility. Put another way, monitoring in such areas does not make
the standard more stringent, but rather affords requisite protection to
the populations, among them at-risk populations, exposed to fine
particulate in these areas. Thus, the EPA has made a determination to
protect all area-wide locations, including those locations with
populations living near major roads that are representative of many
such locations throughout an area. As discussed above, EPA concludes
that the requirement to locate monitors to represent ambient air, along
with other siting requirements, will ensure that monitors represent
PM2.5 concentrations in areas of potential public exposure.

    We do recognize, however, the possibility that some near-road
monitoring stations may be representative of relatively unique
locations versus the more representative area-wide situation mentioned
above. This could occur because an air agency made a siting decision
based on NO2 criteria that resulted in the characterization
of a microscale environment that is not considered area-wide for
PM2.5; for example, due to proximity to a unique source like
a tunnel entrance, nearby major point source, or other relatively
unique microscale hot spot. In these types of scenarios, air agencies
would identify the site as a unique monitor comparable only to the 24-
hour PM2.5 NAAQS per the language in section 58.30, and not
comparable to the annual NAAQS, through the Annual Monitoring Network
Plan process described earlier. Although EPA expects most near-road
PM2.5 monitors to be sited to represent area-wide
conditions, since a vast majority of the near-road stations have yet to
be installed, we believe that providing such clarity and flexibility in
siting and NAAQS comparability is warranted.
    After careful consideration of the public comments, the EPA is
finalizing its decision to add PM2.5 monitors to the near-
road monitoring stations. The EPA is finalizing this decision as the
near-road environment is an area where significant public exposure can
occur, recognizing that this is a gap in the current PM2.5
monitoring networks, and because these PM2.5 monitors will
be collocated with NO2 monitors in the near-road
environment, there will not be a significant additional burden on the
air agencies.\230\ However, in recognition of the comments from air
agencies above, EPA is finalizing a revised and phased schedule for
deployment of the PM2.5 monitors at near-road stations. A
minimum of one PM2.5 monitor in each CBSA with a population
greater than or equal to 2.5 million is to be collocated at a near-road
NO2 monitoring station and must to be operational by January
1, 2015. The remaining CBSAs (i.e., those CBSAs with populations
greater than or equal to 1M, but less than 2.5M) must be operational by
January 1, 2017. This schedule will ensure that air agencies have
sufficient time to learn from deployment of the NO2 monitors
in near-road environments, that the highest population CBSAs begin
operating their PM2.5 monitors in near-road environments
first, and that the remaining PM2.5 monitors are deployed on
the same schedule as the CO monitors (also, required by January 1,
2017).\231\ In consideration of the comments regarding maintaining
neighborhood scale monitoring sites as the largest portion of the
network, the EPA is revising the wording of a requirement that requires
at least one site to be in an area-wide location of expected maximum
concentration, to wording that states that such sites must be in an
area-wide location of expected maximum concentration while also being
at the neighborhood or larger scale of representation.
---------------------------------------------------------------------------

    \230\ The incremental one-time cost of moving the 52 monitors
required to be located in the near-road environment is described in
section X.B--Paperwork Reduction Act.
    \231\ 76 FR 54294, August 31, 2011.
---------------------------------------------------------------------------

iii. Use of PM2.5 Continuous FEMs at SLAMS
    The EPA proposed that each agency specify its intention and
rationale to use or not use data from continuous PM2.5 FEMs
that are eligible for comparison to the NAAQS as part of its annual
monitoring network plan due to the applicable EPA Region Office by July
1 each year. The proposal also provided that the EPA Regional
Administrator would be responsible for approving annual monitoring
network plans where agencies have provided a recommendation that
certain PM2.5 FEMs be considered ineligible for comparison
to the NAAQS.
    In 2006, the EPA finalized new performance criteria for approval of
continuous PM2.5 monitors as either Class III FEMs or ARMs.
At the time of proposal, the EPA had already approved six
PM2.5 continuous FEMs \232\ and there are nearly 200 of
these monitors already operating in State, local, and Tribal networks.
Monitoring agencies have been deploying and field-testing these units
over the last couple of years and the EPA recently compiled an
assessment of the FEM data in relationship to collocated FRMs (Hanley
and Reff, 2011; U.S. EPA, 2011a, pp. 4-50 to 4-51). As described in the
proposal (FR 38983), the EPA found that some sites with continuous
PM2.5 FEMs have an acceptable degree of comparability with
collocated FRMs, while others had poor data comparability that would
not meet the performance criteria used to approve the FEMs (71 FR
61285-61286, Table C-4, October 17, 2006). The EPA is encouraging use
of the FEM data from those sites with acceptable data comparability
including for purposes of comparison to the NAAQS. For sites with
unacceptable data comparability, the EPA is working closely with the
monitoring committee of the NACAA, instrument manufacturers, and
monitoring agencies to document best practices on these methods to
improve the comparability and consistency of resulting data wherever
possible. The EPA believes that the performance of many of these
continuous PM2.5 FEMs at locations with poor data
comparability can be improved to a point where the acceptance criteria
noted above can be met.
---------------------------------------------------------------------------

    \232\ The EPA maintains a list of approved Reference and
Equivalent Methods on its Web site at: http://www.epa.gov/ttn/amtic/criteria.html.
---------------------------------------------------------------------------

    Given the varying data comparability of continuous PM2.5
FEMs noted above, we believe that a need exists for flexibility in the
approaches for how such data are used, particularly for the objective
of determining NAAQS compliance. Accordingly, we proposed that
monitoring agencies address the use of data from PM2.5
continuous FEMs in their annual monitoring network plans due to the
applicable EPA Regional Office by July 1 of each year for any cases
where the agency believes that the data generated by PM2.5
continuous FEMs in their network should not to be compared to the
NAAQS. The annual network plans would include assessments such as
comparisons of continuous FEMs to collocated FRMs, and analyses of
whether the resulting statistical performance would meet the
established approval criteria. Based on these quantitative analyses,
monitoring agencies would have the option of requesting that data from
continuous FEMs be excluded from NAAQS comparison subject to EPA
approval; however, these data could still be utilized for other
objectives such as AQI reporting.
    The issue exists of whether such data use provisions should be
prospective only (i.e., future NAAQS comparability excluded based on an
analysis of recent past performance) or a combination of retrospective
and prospective (i.e., the implications of unacceptable FEM performance
impacting usage of previously collected data as well as future data).
In the proposal, the EPA stated that in most cases, monitoring agencies
should be restricted to addressing prospective data issues to provide
stability and predictability in the long-term PM2.5 data
sets used for supporting attainment decisions. However, in the first
year after this proposed option would become effective, we indicated it
would be appropriate to provide monitoring agencies with a one-time
opportunity to review already reported continuous PM2.5 FEM
data and request that data with unacceptable performance be restricted
(retrospectively) from NAAQS

comparability. Accordingly, in the first year after this rule becomes
effective, we proposed that monitoring agencies have the option of
requesting in their annual monitoring network plans that a portion or
all of the existing continuous PM2.5 FEM data, as
applicable, as well as future data, be restricted from NAAQS
comparability for the period of time that the plan covers.\233\ In the
proposal we stated that annual monitoring network plans in subsequent
years would only need to cover new data for the period of time that the
plan covers.
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    \233\ Data from any PM2.5 monitor being used to meet
minimum monitoring requirements could not be restricted from NAAQS
comparability.
---------------------------------------------------------------------------

    As noted above, in cases where an agency is operating a
PM2.5 continuous FEM that is not meeting the expected
performance criteria used to approve the FEMs (71 FR 61285 to 61286,
Table C-4, October 17, 2006) when compared to their collocated FRMs, an
agency can recommend that the data not be used for comparison to the
NAAQS. However, all required SLAMS would still be required to have an
operating FRM (or other well performing FEM) to ensure a data record is
available for comparison to the NAAQS. In cases where a
PM2.5 continuous FEM was not meeting the expected
performance criteria, and the Regional Administrator has approved a
recommendation that the FEM data not be considered eligible for
comparison to the NAAQS, the data would still be required to be loaded
to AQS; however, these data would be identified distinctly from data
used for comparison to the NAAQS.
    The goal of proposing to allow monitoring agencies the opportunity
to recommend not having data from PM2.5 continuous FEMs as
comparable to the NAAQS is to ensure that only high quality data (i.e.,
data from FRMs which are already well established and new continuous
FEMs that meet the performance criteria used to approve FEMs when
compared to collocated FRMs operated in each agencies network) are used
when comparing data to the PM2.5 NAAQS. Under the current
monitoring regulations, a monitoring agency can identify a
PM2.5 continuous FEM as an SPM, which allows the monitor to
be operated for up to 24 months without its data being used in
comparison to the NAAQS. While 24 months should be sufficient time to
operate the monitor across all seasons, assess the data quality, and in
some cases resolve operational issues with the instrument, it may still
leave some agencies with monitors whose data are not sufficiently
comparable to data from their FRMs. In these cases there may be a
disincentive to continue operating the PM2.5 continuous FEM,
especially in networks where the monitoring data are near the level of
the NAAQS. With the proposed provision, where a monitoring agency can
recommend not having data from PM2.5 continuous FEMs be
comparable to the NAAQS, a monitoring agency can continue to operate
their PM2.5 continuous FEM to support other monitoring
objectives (e.g., diurnal characterization of PM2.5, AQI
forecasting and reporting), while working through options for improved
data comparability while still providing data for comparison to the
NAAQS from an FRM.
    The EPA believes that an assessment of FEM performance should
include several elements based on the original performance criteria.
The Agency also believes that certain modifications to the performance
criteria are appropriate in recognition of the differences between how
monitoring agencies operate routine monitors and how instrument
manufacturers conduct required FRM and FEM testing protocols. The
details below summarize these issues.
    The EPA proposed to use the performance criteria used to approve
the FEMs (71 FR 61285 to 61286, Table C-4, October 17, 2006) for those
agencies that recommend not having data from PM2.5
continuous FEMs be comparable to the NAAQS. To accommodate how routine
monitoring networks operate, the EPA proposed that agencies seeking to
demonstrate insufficient data comparability base their assessment
mainly on collocated data from FRMs and continuous FEMs at monitoring
stations in their network. The EPA does not believe it is practical to
utilize the requirement in table C-4 of 40 CFR part 53 for having
multiple FRMs and FEMs at each site since such arrangements are not
typically found in monitoring agency networks. Accordingly, the
requirement for assessing intra-method replicate precision would be
inapplicable. Another consideration is the range of 24-hour data
concentrations, for instance, the performance criteria in table C-4 of
40 CFR part 53, provides for an acceptable concentration range of 3 to
200 [micro]g/m\3\. However, the EPA notes that during an evaluation of
data quality from two FEMs (U.S. EPA, 2011a, p. 4-50), the Agency found
that including low concentration data was helpful for understanding
whether an intercept or slope was driving a potential bias in an
instrument. Therefore, the EPA proposed that agencies may include low
concentration data (i.e., below 3 [micro]g/m\3\) for purposes of
evaluating the data comparability of continuous FEMs. With regard to
the minimum number of samples needed for the assessment, the EPA notes
that a minimum of 23 sample pairs are specified for each season in
table C-4 of 40 CFR part 53. Having 23 sample pairs per season should
be easily obtainable within one year for sites with a FRM operating on
at least a 1 in 3 day sample frequency and we proposed that this
requirement be applicable to the assessments being discussed here. For
sites on a one in 6 day sampling frequency, two years of data may be
necessary to meet this requirement. The EPA recognizes that it would be
best to assess the data based on the most recently available
information; however, having data across all seasons in multiple years
will provide a more robust data set for use in the data comparability
assessment; therefore, the EPA proposed that data quality assessments
be permitted to utilize up to the last three years of data for purposes
of recommending not having data from PM2.5 continuous FEMs
be comparable to the NAAQS.
    The EPA recognizes that only a portion of continuous
PM2.5 FEMs will be collocated with FRMs, and it would be
impractical to restrict the applicability of data comparability
assessments to only those sites that had collocated FRM and FEM
monitors. In these cases, the monitoring agency will be permitted to
group the sites that are not collocated with an FRM with another
similar site that is collocated with an FRM for purposes of
recommending that the data are not eligible for use in comparison to
the NAAQS. Monitoring agencies may recommend having PM2.5
continuous FEM data eligible for comparison to the NAAQS from locations
where the method has been demonstrated to provide acceptable data
comparability, while also recommending not having it eligible in other
types of areas where the method has not been demonstrated to meet data
comparability criteria. For example, a rural site may be more closely
associated with aged particles where volatilization issues are
minimized resulting in acceptable data comparability between filter-
based and continuous methods, while a highly populated urban site with
fresh emissions with higher volatility may result in higher readings on
the PM2.5 continuous FEM that would not meet the expected
performance criteria as compared to a collocated FRM. In all cases
where a monitoring agency chose to group sites for purposes of
identifying a subset of PM2.5 continuous FEMs that would not
be comparable to the

NAAQS, the assessment submitted with the annual monitoring network plan
would have to provide sufficient detail to support the identification
of which combinations of method and sites would, and would not, be
comparable to the NAAQS, as well as the rationale and quantitative
basis for the grouping and recommendation.
    Most comments received on this issue were from air agencies. All
air agencies either supported the proposal or supported it with a
recommendation to continue to allow for retrospective assessments to be
used such that data would not be compared to the NAAQS, if such an
assessment showed that the data were not of sufficient comparability to
a collocated FRM such that the continuous FEM should not be compared to
the NAAQS. One air agency supported the proposal, except though it had
reservations about how to best group sites together when a particular
PM2.5 continuous FEM is not collocated with a FRM.
    The EPA notes the support by air agencies to finalize this
provision. EPA also notes that all commenters who offered input on the
retrospective use of assessments were supportive of allowing continued
retrospective assessments in annual monitoring networks plans so that
data may be recommended as excluded from comparison to the NAAQS under
certain provisions. However, the EPA has some reservations about how
and under what circumstances such an allowance should be made. The EPA
notes the concern expressed from one agency about how to best group
sites together when considering an assessment.
    On the issue of whether to allow data collected to be
retrospectively excluded from comparison to the NAAQS, the EPA notes
there are a number of considerations, including that several air
agencies support such a policy. The EPA has evaluated how this issue
can be achieved and believes that some consideration should be allowed,
but also wants to ensure there is a consistent and easily recognizable
interpretation of such cases where air agencies recommend excluding
already collected and reported data. To help illustrate the possible
outcomes of how this could work consider the following examples.
Example 1: An agency finds that the bias between a collocated
PM2.5 continuous FEM and FRM are acceptable, but near the
limit of that acceptability and then finds a year later that the
assessment indicates that the bias is just outside the limit of that
acceptability. Such relatively small changes where an assessment
indicates flipping in or out of the acceptable bias are in themselves
acceptable since the overall Data Quality Objectives (DQOs) can still
be met. The overall DQOs can still be met since there are a number of
other factors that feed into the DQOs such as precision, data
completeness, and especially sample frequency, which when operating a
continuous FEM is a daily sample. Daily sampling provides less
uncertainty than sampling at the one-in-three day or one-in-six day
sampling frequencies, which are routinely employed by filter-based FRM
samplers. Therefore, in this example the existing data should still be
compared to the NAAQS, but the air agency should thoughtfully consider
whether to recommend \234\ and the EPA will consider whether to approve
that any new data from PM2.5 continuous FEMs are used in
comparison to the NAAQS. If an air agency recommends to not use a
PM2.5 continuous FEM for comparison to the NAAQS, it would
need to ensure another approved method (i.e., a filter-based FRM/FEM or
other continuous FEM which is performing within acceptable performance
criteria) is operating at the site or sites of interest. This would be
expected for all SLAMS, but at a minimum the design value monitoring
station for the area of interest would be required to have another
approved PM2.5 method (i.e., an FRM, other filter-based FEM,
or other continuous FEM or ARM with acceptable data comparability)
operating on the required sample frequency or more often for that
location. Example 2: A PM2.5 continuous FEM operated by an
air agency is found to have a significant bias compared to a collocated
FRM. If the air agency finds cause to invalidate the data (e.g., a flow
sensor is found to be outside of acceptable limits), then it should
invalidate the relevant data (i.e., data from the period going back to
the last successful flow check or audit or other information that
points to a cause that the flow sensor is not meeting its performance
criteria) for all data uses and there is no follow-up issue of
retrospective analysis. A case of finding cause to invalidate data
would be based on validation criteria found in an air agencies approved
quality assurance project plan (QAPP). Example 3: A PM2.5
continuous FEM operated by an air agency and previously identified as
appropriate to compare to the NAAQS, is found to have a significant and
unacceptable bias compared to a collocated FRM and there is no other
reason to invalidate the data. That is, all other information points to
the data being valid; however, there has been a significant shift in
the comparability of the PM2.5 continuous FEM compared to a
collocated FRM (which itself is found to be operating correctly and
data are valid). A significant shift in the comparability would be
noticeable by comparing assessments for a site from one year to the
next and seeing a significant and unacceptable change in one of the key
statistical metrics used in the evaluation (i.e., additive or
multiplicative bias). Such a case of retrospectively recommending not
using PM2.5 continuous FEM data should also take into
account all other available information that can help inform approving
such a recommendation as part of an annual monitoring network plan. For
example, do data from the PM2.5 performance evaluation
program data also suggest an unacceptable bias for a specific period of
interest with this method as used in the air agencies network? Note:
This type of assessment is often limited by the small number of samples
taken in the PEP program relative to the large number of collocated
samples expected when an FRM and PM2.5 continuous FEM are
collocated. In this type of example, the air agency might want to
recommend not using the continuous FEM data for comparison to the
NAAQS; however, the continuous FEM data could be appropriate for use in
reporting the Air Quality Index (AQI) or other data uses either as is
or if statistically correlated \235\ and corrected back to the
collocated FRM. So in this last example, the PM2.5
continuous FEM data would be stored separately in the EPA's data system
so that they are eligible for use in AQI calculations, but not used in
comparison to the NAAQS, if approved by the EPA. Again, the air agency
should thoughtfully consider and state its position and rationale in
the annual monitoring network plan on whether any future data should be
compared to the NAAQS.
---------------------------------------------------------------------------

    \234\ Through the annual monitoring network plan explained in
Sec.  58.10.
    \235\ The EPA has had a long-standing policy of allowing
PM2.5 continuous data to be statistically correlated and
corrected to use in AQI reporting. A report is available on this:
See ``Data Quality Objectives (DQOs) for Relating Federal Reference
Method (FRM) and Continuous PM2.5 Measurements to Report
an Air Quality Index (AQI), EPA-454/B-02-002, November 2002''.
---------------------------------------------------------------------------

    Another issue to consider is the transparent and consistent use of
PM2.5 continuous FEM data from a method where one air agency
recommends using the data for comparison to the NAAQS and another
specifically recommends to not use it for comparison to the NAAQS. The
use of the annual monitoring plans ensures that the process is
transparent; however, it may not ensure a consistent

approach if one agency recommends exclusion of data and another agency
does not. For example, consider two adjacent air agencies operating the
same make and model of a PM2.5 continuous FEM, where one air
agency recommends using data and the other air agency recommends not
using it for comparison to the NAAQS. While on its face it may seem
straightforward that a method with acceptable comparability to a
collocated FRM should perform similarly in other air agency networks
where they have similar aerosol composition and climate, in practice
there are a number of other variables that affect data comparability.
Such factors that lead to differences in comparability might include
differences in installation, training, development of SOPs, control of
shelter conditions, maintenance of the continuous FEM, and performance
of the FRMs which are being used as the basis of comparison to the
continuous FEM. Also, there may be cases where the concentration levels
are so far away from the level of the NAAQS (either substantially
higher or lower) that it would not matter if the data are excluded or
not, the same NAAQS determination would result. The EPA has considered
these issues and in general believes that it would still be acceptable
for one agency to use data for comparison to the NAAQS, while another
agency does not, even if it's the same method used in adjacent air
agency networks.
    On the issue of grouping sites for purposes of allowing monitors
that are not collocated to be included when recommending a method
should not be compared to the NAAQS, the EPA believes that it is not
necessary to provide specific details on what criteria are necessary to
group sites as air agencies are in the best position to determine a
recommendation of when such sites should or should not be grouped.
However, to illustrate examples of possible ways to group sites, the
air agency could take into account factors such as whether the sites
are all in either a rural or urban location, since urban locations tend
to be impacted more directly by fresh emissions which are known to be
more volatile, or whether there is consistency in the climate for the
sites of interest as might be the case for sites near a large water
body or at a high altitude. The EPA will consider these issues when
evaluating air agency requests for approval.
    The EPA is finalizing its proposal to allow each air agency to
specify its intention to use or not use data from continuous
PM2.5 FEMs that are eligible for comparison to the NAAQS as
part of their annual monitoring network plan due to the applicable EPA
Region Office by July 1 each year where adequate FRM data are
available. The EPA's approval of an annual monitoring network plan
\236\ as a whole, or in part, will constitute concurrence with an air
agency's recommendation to use or not use data from continuous
PM2.5 FEMs as eligible for comparison to the NAAQS, unless
otherwise noted in the approval of the plan. The absence of an air
agency statement specifying a position on use of data from a continuous
PM2.5 FEM for comparison to the NAAQS will be interpreted as
meaning that all such data are applicable for comparison to the NAAQS
following the provisions in Part 50, Appendix N on data handling and
Part 58 on the monitoring requirements. In finalizing this decision the
EPA will ensure, as proposed, that air agencies can identify already
collected data from PM2.5 continuous FEMs that should not be
used for comparison to the NAAQS. After considering comments in support
of allowing additional retrospective assessments, the EPA is also
finalizing an approach of allowing for the continued use of
retrospective assessments to inform when already collected data should
not be compared to the NAAQS, if there has been a significant change in
the assessment of that data from previous years.
---------------------------------------------------------------------------

    \236\ Approval of an annual monitoring network plan is subject
to approval of the EPA Regional Administrator as provided for in
Sec.  58.10(a)(2).
---------------------------------------------------------------------------

c. Revoking PM10-2.5 Speciation Requirements at NCore Sites
    The EPA proposed to revoke the requirement for PM10-2.5
speciation monitoring as part of the current suite of NCore monitoring
requirements. The requirement to monitor for PM10-2.5 mass
(total) at all NCore multi-pollutant sites remains. PM10-2.5
mass monitoring commenced on January 1, 2011 as part of the nationwide
startup of the NCore network (U.S. EPA, 2011a, p. 1-15).
    As part of the process to further define appropriate techniques for
PM10-2.5 speciation monitoring, a public consultation with
the CASAC AAMMS on monitoring issues related to PM10-2.5
speciation was held in February 2009 (74 FR 4196, January 23, 2009).
The subcommittee noted the lack of consensus on appropriate sampling
and analytical methods for PM10-2.5 speciation and expressed
concern that the Agency's commitment to launch the PM10-2.5
monitoring network without sufficient time to analyze the data from a
planned pilot project was premature (Russell, 2009). Based on the noted
lack of consensus on PM10-2.5 speciation monitoring
techniques, the Agency did implement a small pilot monitoring project
to evaluate the available monitoring and analytical technologies.
    The EPA pilot monitoring project was completed in 2011, with plans
to analyze the data and prepare a final report on findings and
recommendations in 2013. At that time, the EPA will consider what
PM10-2.5 speciation sampling techniques, analytical
methodologies, and monitoring design strategies would be most
appropriate as part of a potential nation-wide monitoring deployment.
Such a deployment could be based on the NCore multi-pollutant framework
or some other strategy that allows flexibility and targets measurements
in areas with higher levels of coarse particles.
    All comments received from air agencies and multi-state
organizations were supportive of the removal of the PM10-2.5
speciation requirement.
    A few industry commenters raised concerns about the availability of
PM10-2.5 speciation data for research purposes. One
environmental group opposed revoking the PM10-2.5 speciation
requirement and expressed the need for PM10-2.5 data to
support health effects research and future regulatory efforts.
    The EPA has considered the comments from air agencies that were all
supportive of revoking the requirement, as well as the industry and
environmental groups concerns that PM10-2.5 speciation data
will not be available for research. In considering these comments, the
EPA recognizes the importance of efforts to develop and evaluate
speciation monitoring approaches for PM10-2.5 given that
there is relatively little information available on the chemical and
biological composition of PM10-2.5 and on the health effects
associated with the various components (U.S. EPA, 2009a, section
2.3.4). Without more information on the chemical speciation of
PM10-2.5, the apparent variability in associations with
health effects across locations is difficult to characterize (U.S. EPA,
2009a, section <IP_ADDRESS>). However, the EPA believes that until a final
report on the findings from the pilot study is completed in 2013 and
the results of the study can be considered, PM10-2.5
speciation is not ready for nationwide deployment. Therefore, the EPA
is finalizing its decision to revoke the PM10-2.5 speciation
requirement at NCore stations. Given the continued importance of
characterizing PM10-2.5 species, and given that ongoing and
future research will likely further

inform the development of speciation methods, the appropriateness of
requiring speciation monitoring for PM10-2.5 will be
revisited in future reviews.
d. Measurements for the Proposed New PM2.5 Visibility Index
NAAQS
    The EPA proposed requirements for sampling of PM2.5
chemical speciation in states with large CBSAs. However, as explained
in section VI, the EPA is not finalizing the proposed secondary
PM2.5 visibility index NAAQS and therefore is not finalizing
the proposed monitoring changes associated with that standard.
4. Revisions to the Quality Assurance Requirements for SLAMS, SPMs, and
PSD
a. Quality Assurance Weight of Evidence
    The EPA proposed to use a weight-of-evidence approach for
determining whether the quality of data is appropriate for regulatory
decision-making purposes. While the EPA believes that it is essential
to require a minimum set of checks and procedures in appendix A to
support the successful implementation of a quality system, the success
or failure of any one check or series of checks should not preclude the
EPA from determining that data are of acceptable quality to be used for
regulatory decision-making purposes. Accordingly, the EPA proposed to
include additional wording in appendix A to clarify the role that
appendix A generated data quality indicators have in the overall
quality system that supports ambient air monitoring activities.
    The EPA received eight comments on the weight of evidence approach
with the majority of commenters endorsing the approach. One commenter
felt that the ``paragraph, as written, undermines the importance of the
quality control/quality assurance system dictated in Part 58.'' Some
that supported the approach also provided a word of caution that
``while a common sense approach to the assessment of quality data is
important, minimum requirements are necessary to ensure scientifically-
defensible data is being used in decision making''. The EPA agrees with
the commenter's points that data should be subject to a minimum set of
requirements for data collection, reporting and quality. In developing
the weight of evidence approach, the EPA is not attempting to diminish
the requirements of appendix A but rather ensure that other elements of
a quality system that air agencies implement and are documented in
their QAPP can also be used when judging whether data are valid for a
particular monitoring objective. While the EPA considers the appendix A
requirements the minimum for reporting, it is not the only data that
the EPA and the air agencies use to judge quality. Therefore, if an
appendix A requirement for some reason is not complete, the EPA
concludes that it should not necessarily be the sole reason to declare
the data invalid or unusable. One commenter who felt that the approach
may be appropriate also suggested that the language of the proposal was
vague and may weaken the ability of air monitoring agencies to validate
their own data and instead allows the EPA to make decisions regarding
data validity. In the majority of cases when the quality of ambient air
data is called into question, the EPA Regions and air agencies work
together and reach consensus on data usability. The EPA agrees that the
air agencies know more about their data and it is the air agencies
responsibility to certify the data as valid. In most cases, the EPA and
the air agencies will be in agreement on the validity and usability of
this data. However, since the EPA is responsible for making final
regulatory decisions concerning the NAAQS, in rare cases it may
ultimately have to make a validity decision that the air agencies may
not agree with. After consideration of the general support received,
the EPA will finalize the language as proposed. For the reasons
explained above, the EPA concludes that this will not undermine the
quality assurance system, but rather strengthen it.
    A few commenters, although supporting the weight of evidence
approach, also commented that appendix A minimum requirements should
not only apply to all air quality data collected by state, local, and
tribal agencies, but also to ``secondary'' data collected by other
monitoring efforts. The EPA understands that this term is used by these
commenters to either represent the Chemical Speciation and IMPROVE
Network data being used to calculate light extinction for the secondary
PM2.5 visibility index NAAQS, or for criteria pollutant data
collected by entities other than the state, local or tribal monitoring
organizations. The EPA agrees with the comments that the appendix A
requirements must apply to the CSN and IMPROVE data, if the data were
being used for comparison to the secondary NAAQS, and included the term
``PM2.5 CSN'' to refer to both networks. However, since as
explained in Section VI, the secondary PM2.5 visibility
index NAAQS is not being finalized, the EPA will be removing any text
related to the CSN and IMPROVE requirements from appendix A. If the
term is being used by commenters to refer to criteria pollutant data
collected by entities other than the state, local or tribal monitoring
organizations then the appendix A requirements, as has always been the
case, apply to those monitors.
b. Quality Assurance Requirements for the Chemical Speciation Network
    The EPA proposed to include requirements for flow rate
verifications and flow rate audits for the PM2.5 CSN. Air
agencies currently perform these audits even though they are not
currently required. Thus, although they would be considered a new
requirement, they are not new implementation activities. In addition,
the CSN already includes six collocated sites which the EPA proposes to
include in the 40 CFR part 58 appendix A requirements. The EPA proposed
that PSD sites would not be required to collocate a second set of
instruments for speciated PM2.5 mass monitoring.
    There were no comments that specifically addressed the addition of
collocation and flow rate requirements in appendix A for the chemical
speciation network (CSN). Since these flow rates have historically been
included in the Agencies' CSN Network Quality Assurance Project Plan
and implemented for many years, air agencies may not have considered
them any additional burden on the program. However, as explained in
Section VI, the secondary PM2.5 visibility index NAAQS is
not being finalized; therefore, the EPA will not include these QA
requirements into appendix A since the networks will not produce data
to be used for NAAQS decisions.
c. Waivers for Maximum Allowable Separation of Collocated
PM2.5 Samplers and Monitors
    The EPA proposed to allow waivers, when approved by the EPA
Regional Administrator, for collocation of PM2.5 samplers
and monitors of up to 10 meters so long as the site is at a
neighborhood scale or larger. The EPA proposed to allow waivers for the
maximum allowable distance associated with collocated PM2.5
samplers and monitors. Ensuring PM2.5 continuous FEMs and
PM2.5 FRMs meet collocation requirements (i.e., 1 to 4
meters for PM2.5 samplers with flow rates of less than 200
liters/minute) can be challenging, since in some cases multiple
instruments, FEMs installed in the shelter and FRMs installed on a
platform, are being sited at the same station. The EPA believes that

instruments spaced farther apart could be maintained within the
operational precision of the instruments, especially at sites located
at larger scales of representation (e.g., neighborhood scale and
larger).
    All comments received responded in support of the requirement
allowing up to 10 meter horizontal spacing for sites at a neighborhood
or larger scale of representation. The EPA received no negative
comments on this part of the proposal. During stakeholder presentations
of the proposal, the EPA received a verbal comment that air agencies
were also having difficulty meeting the one meter vertical criteria
since PM2.5 FEMs are typically housed in shelters with
inlets extending through shelter roofs while the collocated FRM
monitors are placed outside, usually on platforms somewhat lower to the
ground. After considering this comment, and further discussion with EPA
Office of Research and Development on spacing requirements, the agency
will amend the appendix A requirements to allow for a 1-3 meter
vertical spacing which may be approved by the Regional Administrator
for sites at a neighborhood or larger scale of representation. In
addition, the language will be amended to allow for waiver approvals
during annual network plan approval processes. Alternatively, the
existing waiver provision outlined in paragraph 10 of Appendix E may be
used.
5. Revisions to Probe and Monitoring Path Siting Criteria
a. Near-Road Component to the PM2.5 Monitoring Network
    The EPA proposed that the probe and siting criteria for the near-
road component of the PM2.5 monitoring network design follow
the same probe and siting criteria as the NO2 near-road
monitoring sites. These requirements would provide that the monitoring
probe be sited ``* * * as near as practicable to the outside nearest
edge of the traffic lanes of the target road segments; but shall not be
located at a distance greater than 50 meters, in the horizontal, from
the outside nearest edge of the traffic lanes of the target road
segment'' (section 6.4 of appendix E to 40 CFR part 58).
    The EPA received comments from several stakeholders on the probe
and siting criteria for PM2.5 monitors in the near-road
environment. One public health group offered detailed comments on the
probe and siting criteria for PM2.5 monitors in near-road
environments. While the commenter offered support for collocating the
PM2.5 monitors with NO2 monitors in the near-road
environment, there was concern expressed regarding allowing monitors at
sites of more than 15 meters from the traffic corridor which is the
source of the air quality concern. The commenter points out that the
EPA's existing rules for siting localized hot spot sites in areas of
highest concentration require sites at microscale locations which
provide for a distance of no more than 15 meters from a major roadway.
Several air agencies offered consistent comments that the inlet of the
PM2.5 monitors should be the same as that of the near-
roadway NO2 monitors; however, one of the commenters
suggested that the requirements for distance to the nearest vertical
wall or obstruction should match the requirements for current micro and
middle scale installations of PM2.5 monitors. The concern
expressed is that a wall or obstruction may disrupt the normal downwind
flow across a roadway.
    In reviewing comments on probe and monitoring path criteria for
PM2.5 monitors in near road environments, and whether to
make any changes, the EPA has several issues to consider. One of the
most important things to consider is what the intended network design
of these monitors should be. As stated in the proposal our goal is to
``better understand the health impacts of these (near-road
PM2.5) exposures,'' that a number of monitoring objectives
can be supported by having near-road PM2.5 monitors, and
that while it might be that the location of maximum concentration of
PM2.5 exposure from near-roadway sources might differ from
the maximum location of NO2 or other pollutants, we proposed
to require that the near-road PM2.5 monitors be collocated
with the planned NO2 monitors. The EPA did not propose to
change the distance from obstructions for PM2.5 monitors in
its proposal.
    As we stated in the proposal, the planned NO2 monitors
are using several relevant factors that are also relevant for siting of
PM2.5 (e.g., average annual daily traffic and fleet mix
[accounting for heavy duty vehicles] by road segment) and that
significant thought and review are going into the design of the near-
road stations. Therefore, the EPA is not persuaded that we should
provide any additional constraints to the siting of the station (i.e.,
the distance from the roadway) than is already provided for in the
NO2 near-road monitor probe and monitoring path siting
criteria. The EPA is concerned that additional constraints (i.e., to
require sites within 15 meters of the road), might have some
advantages, but also might unnecessarily eliminate otherwise useful
near-road locations that on balance might be a better candidate
location.
    The EPA recognizes that there may be cases where the physical
location of a near-road monitoring station is farther than 15 meters,
but no greater than 50 meters from the roadway, but such cases are
presumed to still be the most useful location for the siting of the
NO2 monitors, which we then proposed to collocate with
PM2.5. Regardless of the actual distance of the inlet for
the PM2.5 monitor at the near-road monitoring station, so
long as it is collocated with the approved near-road station for
NO2 and meets existing criteria, the EPA will consider this
site to be appropriate as a near-road PM2.5 monitoring
station. As explained in the proposal, there are a number of reasons to
collect multi-pollutant data in the near-road environment. The EPA
believes that these sites will be sufficient as representative maximum
concentration sites for NO2 and PM2.5 in the
near-road environment. As noted above, where an air agency believes a
different location is a more appropriate site for a near-road
PM2.5 monitor, the EPA can use its discretion in approving a
deviation from the PM2.5 monitoring requirements as already
exists in the network design criteria. A deviation would be appropriate
for consideration where, for example, a state provides quantitative
evidence demonstrating that peak ambient PM2.5
concentrations would occur in a near-road location which meets siting
criteria but is not a near-road NO2 monitoring site. Such
deviations are to be approved by the Regional Administrator as
described in section 4.7.1 of Appendix D to part 58.
    While it is still desirable for the near-road stations to be as
close to the road as practical, there may be differences in the scale
of representation of the near-road PM2.5 monitor from one
location to another, while the NO2 near-road monitors are at
the same scale of representation (i.e., micro-scale) in different
locations. This is a result of the scale of representation being based
on the pollutant at a location and not the location alone. Therefore,
in cases where the station is 20 meters from a major road, the
NO2 measurement may still be micro-scale, while the
PM2.5 measurement would be middle-scale if the average daily
traffic count were sufficiently large enough.\237\ If a site with both
measurements were 10 meters

from a major road they would both be expected to be micro-scale sites.
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    \237\ See Table E-1 in Appendix E to Part 58 for defining the
scale of representation of a PM sampler based on its distance to the
nearest traffic lane and average daily traffic count.
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    In considering the comment on distance from obstructions, the EPA
notes that a monitoring station with multiple measurements is
effectively considered collocated for those measurements, even though
the actual location of the inlets is slightly different from each other
within the station. For example, a gas monitor (e.g., for carbon
monoxide) may be pulling ambient air from a manifold with an inlet
located on one part of a station roof, while a PM monitor is pulling
air directly from its inlet located a few meters away on the same roof.
The EPA believes it is appropriate and consistent with the public
comment above on distance from obstructions to maintain the existing
requirements for distance from obstructions on a pollutant by pollutant
basis, even if they are different for PM2.5 and
NO2 monitors that will be at the same station. Air agencies
will need to consider these distances from obstructions for each
pollutant inlet probe (i.e., >1 meter for NO2 monitors and
>2 meters for PM2.5 monitors) in locating monitors at the
station.
    The EPA is maintaining the existing probe and siting criteria for
PM2.5 monitors; however, we are finalizing the provision
that the required near-road component of the PM2.5
monitoring network design shall be collocated with a required
NO2 monitor at near-road monitoring station. These near-road
NO2 monitoring stations are to be sited ``* * * as near as
practicable to the outside nearest edge of the traffic lanes of the
target road segments; but shall not be located at a distance greater
than 50 meters, in the horizontal, from the outside nearest edge of the
traffic lanes of the target road segment'' (section 6.4 of appendix E
to 40 CFR part 58). The EPA is retaining the existing requirement that
PM2.5 inlets, including those at near road stations, must be
>2 meters from obstructions.
b. CSN Network
    As explained in Section VI, the EPA is not finalizing the proposed
secondary standard based on a PM2.5 visibility index and
therefore will not be finalizing probe and siting criteria associated
with the use of CSN measurements.
c. Reinsertion of Table E-1 to Appendix E
    The EPA proposed to reinsert table E-1 to appendix E of 40 CFR part
58. This table presents the minimum separation distance between
roadways and probes or monitoring paths for monitoring neighborhood and
urban scale ozone (O3) and oxides of nitrogen (NO,
NO2, NOX, NOy). This table was
inadvertently removed during a previous CFR revision process.
    The only comments received on this topic were supportive of the
reinsertion of table E-1; therefore, the EPA is finalizing the
reinsertion of this table, unchanged from its prior iteration, back
into the CFR.
6. Additional Ambient Air Monitoring Topics
a. Annual Monitoring Network Plan and Periodic Assessment
    In October of 2006, the EPA finalized new requirements for each
state, or where applicable, local agency to perform and submit to their
EPA Regional Offices an Assessment of the Air Quality Surveillance
System (40 CFR 58.10). This assessment is required every five years.
The first required five year assessments were due to EPA Regional
Offices by July 1, 2010. The assessments are intended to provide a
comprehensive look at each monitoring agency's ambient air monitoring
network to ensure that the network is meeting the minimum monitoring
objectives defined in appendix D to 40 CFR part 58, whether new sites
are needed, whether existing sites are no longer needed and can be
terminated, and whether new technologies are appropriate for
incorporation into the ambient air monitoring network.\238\
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    \238\ The EPA provides a link to these assessments on EPA's Web
site at: http://www.epa.gov/ttn/amtic/plans.html. A detailed
description of the requirements for the assessments is described in
40 CFR 58.10.
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    Since each agency has completed its first required five-year
assessment, and several monitoring rule requirements have either been
added or changed since this requirement was added in 2006, the EPA
thought it was appropriate to review this requirement and solicit
comment on any possible changes the EPA should consider that may
improve the usefulness of the assessments. Specifically, the EPA
solicited comment on ways to either streamline or add additional
criteria for future assessments.
    The EPA also proposed to remove references to ``community
monitoring zones'' and ``spatial averaging'' in the annual monitoring
network plans due to EPA Regional Offices by July 1 of each year. The
Agency proposed to remove these references since, as discussed in
section VII.A.2 above, the EPA proposed to remove all references to the
spatial averaging option throughout 40 CFR part 50 appendix N.
Consistent with these changes, the EPA also proposed to remove
references to community monitoring zones under the annual monitoring
network plans described in 40 CFR 58.10.
    The EPA received comments from several air agencies on the five
year assessments. Most comments on the five year assessments focused on
the type and usefulness of assessment tools made available to air
agencies during the last review. Of specific note were concerns that
assessment tools used to evaluate networks on a regional or national
basis do not provide the spatial resolution necessary to adequately
assess state networks on a scale most useful to air agencies. This is
especially true when attempting to evaluate smaller scale monitoring or
pollutant gradients associated with near-road and source oriented
monitoring. Suggestions for improvement identified the need for the EPA
to work closely with air agencies early in the next cycle of
assessments (due in 2015) so that any tools developed can be of benefit
to the questions air agencies need to address for their programs. The
EPA did not receive any comments on removing references to community
monitoring zones specifically as it pertains to their listing in the
annual monitoring network plans described in 40 CFR 58.10.\239\
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    \239\ Comments on the substantive question of whether to revoke
references to community monitoring zones were addressed in section
VIII.B.1.
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    The EPA took comment on potential improvements to the five year
assessments. All the recommendations received focused on the types of
assessments to perform and ensuring that the EPA works closely with air
agencies so that assessments will be of benefit to the air agencies. No
specific recommendations were made to add or remove any of the
requirements of the five year assessments and consequently the EPA is
not making any changes. The EPA intends to work with air agencies to
ensure future tools are as helpful as practicable.
    Consistent with the decision to end the practice of spatial
averaging, the EPA is finalizing the removal of language that
references ``community monitoring zones'' and ``spatial averaging'' in
the annual monitoring network plans due to EPA Regional Offices by July
1 of each year.
b. Operating Schedules
    The EPA generally requires PM2.5 SLAMS to operate on at
least a 1-day-in-3 sampling schedule, unless a reduced sampling
frequency is approved such as might be the case with

a site that has a collocated continuous operating PM2.5
monitor.\240\ However, in the 2006 monitoring rule amendments, the EPA
finalized a new requirement for the operating schedule of
PM2.5 SLAMS sites (40 CFR 58.12). The new requirement stated
that sites with a design value within plus or minus five percent of the
24-hour PM2.5 NAAQS must have an FRM or FEM operating on a
daily sampling schedule. This requirement was included to minimize any
statistical error associated with the form of the 24-hour
PM2.5 NAAQS (i.e., the 98th percentile). In section III.F,
the Administrator is finalizing revisions to the level of the primary
annual PM2.5 NAAQS. Accordingly, possible changes to
sampling frequency requirements were also considered.
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    \240\ All NCore stations must operate on at least a one-in-three
day sample frequency for filter-based PM sampling.
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    The EPA had previously considered how sample frequency affects the
Data Quality Objectives in a consultation with the CASAC AAMMS in
September of 2005 (70 FR 51353 to 51354, August 30, 2005). As a result
of that consultation, the EPA proposed (71 FR 2710 to 2808, January 17,
2006) and finalized (71 FR 61236 to 61328, October 17, 2006) changes to
the sample frequency requirements as part of the monitoring rule
changes in 2006. In that work, the EPA demonstrated that having a
higher sample count is generally more useful to minimize uncertainty
for a percentile standard than an annual average. Given the decision to
strengthen the primary annual PM2.5 NAAQS and the known
burden of performing daily sampling using the filter-based samplers
that are still a mainstay in monitoring agency networks, the issue of
needing daily sampling for sites that have design values close to the
level of the 24-hour PM2.5 standard was reconsidered if the
site already has a design value above the level of the primary annual
PM2.5 NAAQS.
    In a related issue, since the EPA finalized the requirement for
daily sampling at sites within 5 percent of the 24-hour
PM2.5 NAAQS in 2006, there has been confusion over the
procedures for adjusting sample frequencies, where necessary, to
account for variations in year-to-year design values. Therefore, the
EPA proposed to revise this requirement in the following ways: (1) The
EPA proposed that monitors would only be required to operate on a daily
schedule if their 24-hour design values were within five percent of the
24-hour PM2.5 NAAQS and the site had a design value that was
not above the level of the annual PM2.5 NAAQS. (2) The EPA
proposed that review of data for purposes of determining applicability
of this requirement at a minimum be included in each agency's annual
monitoring network plan described in 40 CFR 58.10 based on the three
most recent years of ambient data that were certified as of the May 1
annual deadline. However, monitoring agencies may request changes to
sample frequency at any time of the year by submitting such a request
to their applicable EPA Regional Office. Changes in sampling frequency
are expected to take place by January 1 of the following year.
Increased sampling is expected to be conducted for at least three
years, unless a reduction in sampling frequency has been approved in a
subsequent annual monitoring network plan or otherwise approved by the
Regional Administrator.
    Comments received on the sample frequency requirements for
PM2.5 were from air agencies, who were generally supportive
of the EPA's proposed approach.
    The EPA is finalizing its proposal to modify the sample frequency
requirements for triggering daily sampling so that only those areas
with 24-hour design values within five percent of the 24-hour
PM2.5 NAAQS and where the design value site is not above the
level of the annual PM2.5 NAAQS would be required to operate
on a daily sample frequency. The EPA is also finalizing all other
aspects of this part of the proposal.
c. Data Reporting and Certification for CSN and IMPROVE Data
    The EPA is not finalizing its proposal on minor changes to
reporting and certification of data associated with CSN and IMPROVE
networks since as explained in Section VI, EPA is not finalizing a
secondary standard to support visibility impairment that would have
used CSN and IMPROVE data.
d. Requirements for Archiving Filters
    The EPA proposed to extend the requirement for archival of
PM2.5, PM10, and PM10-2.5 filters from
manual low-volume samplers (samplers with a flow rate of less than 200
liters/minute) at SLAMS from one year after data collection to five
years after data collection. The archive of low-volume PM filters is an
important resource for on-going research and development of emission
control strategies and for use in health and epidemiology research.
During a workshop on Ambient Air Quality Monitoring and Health Research
in 2008, retaining filters for laboratory analysis was identified as a
key recommendation to provide daily measurements of metals and elements
(U.S. EPA, 2008d, pp. 17 to 21). The EPA's previous requirement of one-
year is not sufficiently long for retrospective analysis of important
episodes and for use in long-term epidemiology research. Since
initially requiring filter archival of low-volume PM filters in 1997,
the EPA has always recommended longer archiving of filters and most
agencies are already doing so. However, a small number of agencies have
reported discarding older filters, despite the minimal cost of storing
these filters. Since cold storage of a large number of filters may be
cost prohibitive and of little benefit in retaining key aerosol species
in the x-ray fluorescence (XRF) analyses, the EPA proposed to minimize
the costs of retaining filters by only requiring cold storage during
the first year after sample collection.
    All comments received on this issue were from air agencies, which
were largely supportive of such a change to this requirement. One air
agency did report that it would present a hardship to store filters for
such a long period of time as they did not have the room to support
such a requirement.
    The EPA is finalizing the requirement for archival of
PM2.5, PM10, and PM10-2.5 filters from
manual low-volume samplers (samplers with a flow rate of less than 200
liters/minute) at SLAMS for a minimum of five years after data
collection, with cold storage only required for the first 12 months of
archiving. The EPA will work closely with air agencies through its EPA
Regional Offices and laboratories to support any air agency unable to
store filters for the new five year requirement.

IX. Clean Air Act Implementation Requirements for the PM NAAQS

    This section of the preamble discusses the general approach for air
agencies \241\ to meet certain CAA requirements for implementing the
revised primary annual PM2.5 NAAQS as part of the revised
suite of NAAQS for PM. In accordance with CAA section 107(d), the PM
NAAQS revisions trigger a process under which states must and tribes
may make recommendations to the Administrator regarding area
designations, and the EPA will take final action on those designations.
Under section 110 of the CAA and related provisions, states are also
required to submit, for the EPA's

approval, SIPs that provide for the attainment and maintenance of the
revised NAAQS through control programs directed at sources of direct
PM2.5 and precursor emissions. If a state fails to adopt and
implement the required SIPs by the time periods provided in the CAA,
the EPA has responsibility under the CAA to adopt a Federal
Implementation Plan (FIP) to assure that areas attain the NAAQS in an
expeditious manner. Additionally, emissions sources and air agencies
must address the revised PM NAAQS in the context of preconstruction air
permitting requirements and the transportation conformity and general
conformity processes.
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    \241\ This and all subsequent references to ``air agency'' are
meant to include state, local and tribal agencies responsible for
the implementation of a PM2.5 control program.
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    In addition to today's revisions to the primary annual
PM2.5 NAAQS, the EPA is taking final action on a PSD
implementation provision. To facilitate timely implementation of the
PSD requirements resulting from the revised NAAQS, which would
otherwise become applicable to all PSD permit applications upon the
effective date of this final PM NAAQS rule, the EPA is finalizing a
grandfathering provision for pending permit applications. This final
rule incorporates revisions to the PSD regulations that provide for
grandfathering of PSD permit applications that have been determined to
be complete on or before December 14, 2012 or for which public notice
of a draft permit or preliminary determination has been published as of
the effective date of today's revised PM2.5 NAAQS.
Accordingly, for projects eligible under the grandfathering provision,
sources must meet the requirements associated with the prior primary
annual PM2.5 NAAQS rather than the revised primary annual
PM2.5 NAAQS.
    The EPA also proposed to implement a surrogacy approach for
addressing PSD requirements associated with the proposed distinct
secondary visibility index NAAQS. As described in section VI, the EPA
is not finalizing a distinct secondary visibility index standard at
this time and therefore the proposed surrogacy approach for
implementing such a standard under the PSD program is unnecessary.
Additionally, as discussed in section IV, today's final rule does not
include any changes to the existing PM10 NAAQS. Accordingly,
this section of the preamble does not include any discussion of
implementation specifically related to the PM10 NAAQS.
    Under the schedule in section 107(d)(1) of the CAA, as confirmed in
this action, state Governors and tribes, if they choose, are required
to submit their initial designation recommendations for the revised
primary annual PM2.5 NAAQS to the EPA no later than 1 year
following promulgation of the revised NAAQS (i.e., by December 13,
2013). The EPA will provide designation guidance to air agencies
shortly after today's final NAAQS rule to assist them in formulating
their designation recommendations. The EPA intends to complete initial
designations for the revised primary annual PM2.5 NAAQS by
December 12, 2014 using available air quality data from the current
PM2.5 monitoring networks.
    In addition to describing the PSD grandfathering provision being
finalized in today's rule and responding to associated public comments,
this section of the preamble describes the EPA's future plans for
addressing the remaining aspects of implementation, such as
infrastructure SIP submittals and nonattainment area planning. In the
proposed rule, the EPA solicited preliminary comment on some of the
issues that the Agency anticipates will need to be addressed in future
guidance or regulatory actions related to implementation of the revised
PM2.5 NAAQS. The EPA received comments on a few of these
issues and, as explained in greater detail later in this section, the
EPA either has considered or will consider, as appropriate, all
substantive comments received as future guidance and proposed rules are
developed.

A. Designation of Areas

1. Overview of Clean Air Act Designations Requirements
    After the EPA establishes or revises a NAAQS, the CAA requires the
EPA and states to take steps to ensure that the new or revised NAAQS is
met. The first step, known as the initial area designations, involves
identifying areas of the country that either meet or do not meet the
new or revised NAAQS along with the nearby areas contributing to
violations. Section 107(d)(1) of the CAA states that, ``By such date as
the Administrator may reasonably require, but not later than 1 year
after promulgation of a new or revised national ambient air quality
standard for any pollutant under section 109, the Governor of each
state shall * * * submit to the Administrator a list of all areas (or
portions thereof) in the State'' that designates those areas as
nonattainment, attainment, or unclassifiable.\242\ Section