section IX.F.1.a of this preamble, a grandfathering provision for
certain PSD permits that are already in process, and is also proposing,
in section IX.F.1.c, a surrogacy approach for implementing PSD
permitting requirements for the proposed secondary PM2.5
visibility index NAAQS. These provisions will assure that NSR
permitting will be able to continue using provisions and processes
virtually identical to those already in place for the existing
PM2.5 NAAQS, except that, in evaluating whether a source
causes or contributes to a NAAQS violation, an applicant would need to
compare the source's impacts to a different level and form of the
primary annual standard, if finalized as proposed. As discussed in more
detail in the following sections, the EPA is not now proposing to
change the PM2.5 increments, nor are we proposing to revise
screening tools that are now used to implement PSD for
PM2.5, such as the significant emission rate, used as a
threshold for determining whether a given project is subject to major
NSR permitting requirements under both PSD and NNSR; the significant
impact levels, used to determine the scope of the required air quality
analysis that must be carried out in order to demonstrate that the
source's emissions will not cause or contribute to a violation of any
NAAQS or increment under the PSD program; or the significant monitoring
concentration, a screening tool used to determine whether it may be
appropriate to exempt a proposed source from the requirement to collect
pre-construction ambient monitoring data as part of the required air
quality analysis.
1. Prevention of Significant Deterioration
    The PSD requirements set forth under part C (sections 160 through
169) of the CAA apply to new major stationary sources and major
modifications locating in areas designated as ``attainment'' or
``unclassifiable'' with respect to the NAAQS for a particular
pollutant. The EPA regulations addressing the statutory requirements
under part C for a PSD permit program can be found at 40 CFR 51.166
(containing the PSD requirements for an approved SIP) and 40 CFR 52.21
(the federal PSD permit program). For PSD, a ``major stationary
source'' is one with the potential to emit 250 tons per year (tpy) or
more of any air pollutant, unless the source or modification is
classified under a list of 28 source categories contained in the
statutory definition of ``major emitting facility'' in section 169(1)
of the CAA. For those 28 source categories, a ``major stationary
source'' is one with the potential to emit 100 tpy or more of any air
pollutant. A ``major modification'' is a physical change or a change in
the method of operation of an existing major stationary source that
results in a significant emissions increase and a significant net
emissions increase of a regulated NSR pollutant. Under PSD, new major
sources and major modifications must apply best available control
technology (BACT) for each applicable pollutant and conduct an air
quality analysis to demonstrate that the proposed construction will not
cause or contribute to a violation of any NAAQS or PSD increments (see
CAA section 165(a)(3); 40 CFR 51.166(k); 40 CFR 52.21(k)). PSD
requirements also include in appropriate cases an analysis of potential
adverse impacts on Class I areas (see sections 162 and 165 of the CAA).

    PSD permitting requirements first became applicable to
PM2.5 in 1997 when EPA established a NAAQS for
PM2.5 (Seitz, 1997). The EPA's regulations define the term
``regulated NSR pollutant'' to include ``[a]ny pollutant for which a
national ambient air quality standard has been promulgated and any
pollutant identified [in EPA regulations] as a constituent or precursor
to such pollutant'' (40 CFR 51.166(b)(49); 40 CFR 52.21(b)(50)).\216\
In addition, on May 16, 2008, the EPA amended its rules to identify
certain PM2.5 precursors (SO2 and NOX)
as regulated NSR pollutants and adopt other provisions, such as a
significant emissions rate for PM2.5, to facilitate
implementation of PSD and NNSR program requirements for
PM2.5 (73 FR 28321). States were required to revise their
SIPs by May 16, 2011 to incorporate the required elements of the 2008
final rule.
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    \216\ Under various provisions of the CAA, PSD requirements are
applicable to each pollutant subject to regulation under the CAA,
excluding hazardous air pollutants. The definition of ``regulated
NSR pollutant'' also includes pollutants subject to any standard
under section 111 of the CAA or any Class I or II substance subject
to title VI of the CAA.
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    On October 20, 2010, the EPA again amended the PSD rules at 40 CFR
51.166 and 52.21 to add PSD increments as well as two screening tools
for PM2.5--significant impact levels (SILs) and a
significant monitoring concentration (SMC) (75 FR 64864). The October
2010 final rule became effective on December 20, 2010. The EPA
indicated that the SILs and SMC for PM2.5, while useful
tools, are not considered mandatory elements of an approvable SIP;
thus, no schedule was imposed on states for addressing those screening
tools in their PSD rules. For the portions of the rule that addressed
the PSD increments for PM2.5, states are required to submit
the necessary SIP revisions (at least as stringent as the PSD
requirements at 40 CFR 51.166) to EPA for approval within 21 months
from the date on which the EPA promulgated the new PM2.5
increments--by July 20, 2012. This particular schedule is prescribed by
the CAA specifically for the adoption of new PSD increments in state
PSD programs. Sources for which PSD permits are issued pursuant to the
federal PSD program at 40 CFR 52.21 after October 20, 2011, must
determine their impact on the PM2.5 increments.
    The PSD program currently regulates emissions of PM using several
indicators of particles, including ``particulate matter emissions'' (as
regulated under various new source performance standards under 40 CFR
part 60), ``PM10 emissions,'' and ``PM2.5
emissions.'' The latter two emission indicators are designed to be
consistent with the ambient air indicators for PM that the EPA
currently uses in the PM NAAQS. As already noted, the PSD program also
limits PM2.5 concentrations by regulating emissions of
gaseous pollutants that result in the secondary formation of
particulate matter. Those pollutants, known as PM2.5
precursors, generally include SO2 and NOX.
    In addition to the NAAQS revisions themselves, for which proposed
and other possible implementation approaches are described further
below, the EPA is proposing certain clarifications to the existing
monitoring regulations codified at 40 CFR 58.30 (Special considerations
for data comparisons to the NAAQS). These proposed clarifications are
presented in detail in section VIII.B.2 of this preamble. The
monitoring regulations provide a basis for determining whether specific
monitoring sites are comparable to specific NAAQS. By extension, the
EPA has used the principles for making these determinations for
monitoring sites to also guide permitting authorities in assessing the
comparability of specific receptor locations involved in PSD air
quality analyses. Receptors are used in PSD modeling analyses to
predict potential air quality impacts in the vicinity of the proposed
new or modified facility and in some cases also at more distant Class I
areas. The EPA will continue to use these principles in guiding PSD
modeling analysis design. Accordingly, if the proposed PM NAAQS
revisions and monitoring regulation clarifications described previously
are finalized, the EPA will advise permitting agencies to qualify or
disqualify specific receptor locations used in PSD air quality analyses
consistent with those final provisions, and we will do so ourselves
when we are the permitting authority.
    With regard to the specific revisions being proposed to the PM
NAAQS, today's action, if finalized as proposed, would affect sources
applying for PSD permits in several ways. We first discuss the
implications for PSD with respect to the proposed revised primary
annual PM2.5 standard (some of which also apply to the
proposed secondary PM2.5 visibility index standard), and
then the unique implications for PSD with respect to the proposed
secondary PM2.5 visibility index standard.
a. Grandfathering Provision
    As discussed previously in this preamble, the EPA is proposing to
revise the level of the primary annual PM2.5 NAAQS and
establish a secondary PM2.5 visibility index NAAQS.\217\
Longstanding EPA policy interprets the CAA and EPA regulations at 40
CFR 52.21(k)(1) and 51.166(k)(1) to generally require that PSD permit
applications must include a demonstration that new sources and
modifications will not cause or contribute to a violation of any NAAQS
that is in effect as of the date the PSD permit is issued (Page, 2010a;
Seitz, 1997). Thus, if the proposed revision to the primary annual
PM2.5 NAAQS and the proposed secondary PM2.5
visibility index NAAQS are promulgated, any proposed new and modified
sources with permits pending at the time those PM2.5 NAAQS
changes take effect would be expected to demonstrate compliance with
them, absent some type of transition provision exempting such
applications from the new requirements.
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    \217\ The EPA is also proposing to revise the form of the annual
primary standard by removing the option for spatial averaging.
However, this provision has played no role in PSD so its removal has
no implications for PSD.
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    In order to provide for a reasonable transition into the new PSD
permitting requirements that will result from the proposed revision of
the primary annual NAAQS, the proposed addition of a distinct secondary
NAAQS for visibility protection, and the changes to the monitoring
requirements discussed earlier, the EPA proposes to add a
grandfathering provision to the federal PSD program codified at 40 CFR
52.21 that would apply to certain PSD permit applications that are
pending on the effective date of the revised PM NAAQS. The EPA proposes
that the grandfathering provision would apply specifically to pending
PSD permit applications for which the proposed permit (draft permit or
preliminary determination) has been noticed for public comment before
the effective date of the revised NAAQS.
    The proposed grandfathering provision would not be the first such
grandfathering provision adopted by the EPA. The Agency previously
recognized that the CAA provides discretion for the EPA to grandfather
PSD permit applications from requirements that become applicable while
the application is pending (45 FR 52683, Aug. 7, 1980; 52 FR 24672,
July 1, 1987; U.S. EPA, 2011c, pp. 54 to 61). As discussed in more
detail in these referenced actions, section 165(a)(3) of the CAA
requires that a permit applicant demonstrate that its proposed project
will not cause or contribute to a violation of any NAAQS. At the same
time, section 165(c) of the CAA requires that a PSD permit be

granted or denied within 1 year after the permitting authority
determines the application for such permit to be complete. In addition,
section 301 of the CAA authorizes the Administrator ``to prescribe such
regulations as are necessary to carry out his functions under this
chapter.'' When read in combination, these three provisions of the CAA
provide the EPA with the discretion to promulgate regulations to
grandfather pending permit applications from having to address a
revised NAAQS where necessary to achieve a balance between the CAA
objectives to protect the NAAQS on the one hand, and to avoid delays in
processing PSD permit applications on the other. The EPA has also
construed section 160(3) of the CAA, which states that a purpose of the
PSD program is to ``insure that economic growth will occur in a manner
consistent with the preservation of existing clean air resources'' to
call for a balancing of economic growth and protection of air quality
(70 FR 59587 to 59588, Oct. 12, 2005). The reasoning of those prior EPA
actions is also applicable to the promulgation of revised PM
NAAQS.\218\
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    \218\ In one extraordinary case where the EPA had not previously
adopted a grandfathering provision in regulations and had
significantly exceeded the deadline in section 165(c) of the CAA,
the EPA has taken the position that it may grandfather through
adjudication respecting a specific source, thus interpreting its
regulations, as well as other authorities, to allow grandfathering
in that extraordinary circumstance (U.S. EPA, 2011c, pp. 67 to 71).
Although grandfathering without a specific exemption in regulations
was justified based on the particular facts in that specific
instance, the EPA generally believes the preferred approach is to
enable grandfathering through express regulatory exemptions of the
type proposed in this action (U.S. EPA, 2011c, p. 68).
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    The CAA provides the EPA with discretion to establish the
appropriate milestone within the permitting process for determining
that a permit application is eligible for grandfathering (U.S. EPA,
2011c, p. 81). For example, in 1987, the EPA used the date of submittal
of a complete permit application as the milestone upon which to base
the grandfathering of a source from new permitting requirements
associated with the revisions made to the PM NAAQS at that time (52 FR
24672, July 1, 1987 at 24703). In the context of the implementation of
the revisions to the PM NAAQS that are being proposed today, the EPA is
proposing to use a different milestone to establish the date before
which permits may be grandfathered. Accordingly, to avoid unreasonable
delays in permit processing and issuance, and based on basic principles
of fairness and equity, we believe that it is appropriate to allow
pending permit applications that have reached the notice and comment
period on a proposed permit (that is, a notice has been issued for
public comment on the proposed permit action) by the effective date of
the revised PM NAAQS to continue being processed in accordance with the
PM NAAQS requirements in place as the time of the public notice on the
proposed permit.\219\
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    \219\ There may be proposed permits for which a public notice
was issued prior to October 20, 2011, which is the date that
PM2.5 increments became applicable requirements for any
newly issued federal PSD permits under 40 CFR 52.21. It is not the
EPA's intention that the grandfathering provision proposed today
should relieve such a permit from the requirement to demonstrate
compliance with those new PM2.5 increments, for which the
EPA did not adopt any grandfathering provisions but deferred
implementation in accordance with the requirements of the CAA.
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    Before a proposed permit is issued for public comment, the
applicant still has a reasonable opportunity to amend its permit
application to address new or revised NAAQS that become effective while
the reviewing authority's preliminary consideration of the application
is underway. Furthermore, the reviewing authority has the opportunity
to review additional material and revise its fact sheet or statement of
basis before beginning the public comment period on such a permit.
However, if the EPA and other reviewing authorities were to apply new
permitting requirements based on the revised PM NAAQS after the public
comment period has begun, this would unduly delay the processing of the
permit application by potentially requiring an additional public
comment period and additional work by the reviewing authority at a time
when it should be focused on considering public comments and preparing
a final permit decision in order to conclude its review of a permit
application in a timely manner. Through this proposal, the EPA is
providing notice to current and future permit applicants that they may
have to provide an analysis showing that their facility will not cause
or contribute to a violation of the revised NAAQS for PM if a proposed
permit is not issued for public comment before such NAAQS become
effective.
    Accordingly, the EPA proposes to amend the federal PSD regulations
at 40 CFR 52.21 to provide a grandfathering provision to allow for the
continued review of permits proposed before a revision to the 2006 p.m.
NAAQS under the PM NAAQS that applied at the time of the public notice
on the proposed permit. The EPA also proposes that states that issue
PSD permits under a SIP-approved PSD permit program should have the
discretion to ``grandfather'' proposed PSD permits in the same manner
under these same circumstances. Thus, the EPA also proposes to revise
section 40 CFR 51.166 to provide a comparable exemption applicable to
SIP-approved PSD programs.
    In developing the proposed grandfathering provision, the EPA
considered whether such a provision should include a sunset clause. A
sunset clause would add a time limit beyond which an otherwise eligible
permit action would no longer be grandfathered from PSD permitting
requirements associated with a revised PM NAAQS. Consistent with past
grandfathering actions described above, the EPA is not proposing to
include a sunset clause for the proposed grandfathering provision.
Permit applicants and reviewing authorities already have strong
incentives to process applications and issue draft permits in a timely
manner, and the EPA does not believe that the addition of a sunset
clause to the proposed grandfathering provision would add meaningful
additional incentive for sources or permitting authorities to expedite
permitting processes. Furthermore, the EPA believes that a sunset
clause could in fact result in further delays for permit actions that
qualify for the proposed grandfathering provision in circumstances
where unrelated and not reasonably avoidable factors cause draft permit
issuance and public notice to lapse beyond the sunset date. In such
cases, the already delayed permit action would be further delayed to
address PSD permitting requirements associated with the revised PM
NAAQS, potentially triggering a domino effect of newly applicable
requirements. As such, the EPA believes a sunset clause would diminish
the value of the grandfathering provision and likely introduce
additional complexities in relation to specific permit actions.
However, the EPA solicits comment on whether a sunset clause would be
appropriate under certain circumstances, and if so, what time limits
would be placed on the grandfathering period associated with the
revised PM NAAQS.
b. Recent Guidance Applicable to the Proposed Revised Primary Annual
PM2.5 NAAQS
    Today's proposal to revise the level of the primary annual
PM2.5 NAAQS from 15.0 [micro]g/m\3\ to a level within the
range of 12.0 and 13 [micro]g/m\3\ and to establish a distinct
secondary PM2.5 visibility index NAAQS generally will
require proposed new major stationary sources and modifications to take
these changes into

account as part of the required air quality analysis to demonstrate
that the proposed emissions increase will not cause or contribute to a
violation of the PM NAAQS. If the PM NAAQS are revised as proposed, and
when effective, proposed sources that are not grandfathered from the
new requirements (as described in section IX.F.1.a) would be required
to demonstrate compliance with the suite of PM NAAQS, including the
revised primary annual PM2.5 NAAQS and the proposed
secondary PM2.5 visibility index NAAQS.
    PSD applicants are currently required to demonstrate compliance
with the existing primary and secondary annual and 24-hour
PM2.5 NAAQS and will need to consider their impact on the
revised primary annual PM2.5 NAAQS, if finalized. To assist
sources and permitting authorities in carrying out the required air
quality analysis for PM2.5 under the existing standards, the
EPA issued, on March 23, 2010, a guidance memorandum that recommends
certain interim procedures to address the fact that compliance with the
24-hour PM2.5 NAAQS is based on a particular statistical
form, and that there are technical complications associated with the
ability of existing models to estimate the impacts of secondarily
formed PM2.5 resulting from emissions of PM2.5
precursors (Page, 2010b). For the latter issue, the EPA recommended
that special attention be given to the evaluation of monitored
background air quality data, since such data readily account for the
contribution of both primary and secondarily formed PM2.5.
To provide more detail and to address potential issues associated with
the modeling of direct and precursor emissions of PM2.5, the
EPA is now developing additional permit modeling guidance that will
recommend appropriate technical approaches for conducting a
PM2.5 NAAQS compliance demonstration for the existing
PM2.5 NAAQS, which includes more adequate accounting for
contributions from secondary formation of ambient PM2.5
resulting from a proposed new or modified source's precursor emissions.
(As discussed in the next section, these recommended approaches may be
extended to the proposed secondary NAAQS as well under a surrogacy
approach). To this end, the EPA discussed this draft guidance in March
2012 at the EPA's 10th Modeling Conference.\220\ Based on its review of
public comments received and further technical analyses, the EPA
intends to issue final guidance by the end of calendar year 2012.
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    \220\ The presentation on this draft guidance was posted on the
EPA Web site at: http://www.epa.gov/ttn/scram/10thmodconf.htm.
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c. Surrogacy Approach for the Proposed Secondary PM2.5
Visibility Index NAAQS
    As summarized in section VI.F of this preamble, the EPA is
proposing a distinct secondary NAAQS for PM2.5 that will
provide protection against visibility impairment, measured in terms of
a visibility index using a calculated PM2.5 light extinction
indicator (see section VI.D.1 above). The PM2.5 visibility
index values are determined using a six-step procedure involving 24-
hour speciated PM2.5 concentration data together with
climatological relative humidity factors. The EPA plans to calculate
design values for the proposed secondary PM2.5 visibility
index NAAQS using the procedures described in section VII.A.5 above,
relying upon ambient PM2.5 speciation measurement data
available through the CSN or IMPROVE methods and spatial interpolation
of historical relative humidity data.
    As explained above, the PSD program requires individual new or
modified stationary sources to carry out an air quality analysis to
demonstrate that their proposed emissions increases will not cause or
contribute to a violation of any NAAQS. Such a demonstration for the
proposed secondary PM2.5 visibility index NAAQS could
require each PSD applicant to predict, via air quality modeling, the
visibility impairment that will result from its proposed emissions in
conjunction with an assessment of existing air quality (visibility
impairment) conditions. Under 40 CFR 51.166(l)(1) and 40 CFR
52.21(l)(1), all applications of air quality modeling for purposes of
determining whether a new or modified source will cause or contribute
to a NAAQS violation, including a violation of the proposed secondary
visibility index NAAQS for PM2.5, must be based upon air
quality models specified in appendix W to 40 CFR part 51. Currently
there are no air quality models identified in Appendix W that are
recommended for regulatory applications (Appendix W to 40 CFR part 51,
Section 3.1.1(b)) for addressing the atmospheric chemistry associated
with secondary formation of PM2.5. Thus, if this
demonstration were to be attempted using the six-step procedure that
the EPA is proposing to use for calculating PM2.5 visibility
index design values, significant technical issues with the modeling
procedures could arise. Those technical difficulties include the
current limitations on speciated source-specific emissions data for
model input; the lack of an EPA-approved air quality model with the
capability to address the atmospheric chemistry associated with
secondary formation of PM2.5; and the lack of PSD screening
tools for streamlining the air quality analysis process. In addition,
due to the limited monitoring network for speciated PM2.5,
some sources may not be able to rely on existing speciated monitoring
data to adequately represent the background air quality and thereby
satisfy preconstruction monitoring requirements. Consequently, those
prospective PSD sources could be required to collect new data in order
to determine the representative background concentrations of
PM2.5 species (i.e., those required for calculating the
PM2.5 visibility index values as described in section
VII.A.5 above).
    Recognizing these difficult technical issues, the EPA believes that
there is an essential need to provide alternative approaches to enable
prospective PSD sources to demonstrate that they will not cause or
contribute to a violation of the secondary PM2.5 visibility
index NAAQS, if finalized as proposed. To meet this need, the EPA
believes that it is reasonable to allow the use of a surrogacy
approach, as discussed below, for at least the interim period while
technical issues are being resolved, but which could potentially be
continued beyond such time if shown to be appropriate. The EPA is
providing notice of its intent to follow such an approach and is asking
for comments on the approach as discussed in the remainder of this
section. The Agency believes that following this approach will
facilitate the transition to a workable PSD permitting approach under
the proposed secondary PM2.5 visibility index NAAQS.
    To support consideration of alternative approaches that could be
used by prospective PSD sources, the EPA conducted a two-pronged
technical analysis of the relationships between the proposed
PM2.5 visibility index standard and the 24-hour
PM2.5 standards (Kelly, et al., 2012). The first prong of
the analysis addressed aspects of a PSD significant impact analysis by
evaluating whether an individual source's impact resulting in a small
increase in PM2.5 concentration would produce a comparably
small increase in visibility impairment. This analysis included
estimates of PM2.5 speciation profiles based on direct
PM2.5 emission profiles for a broad range of source
categories and for theoretical upper and lower bound scenarios. The
analysis indicated that small increases in PM2.5
concentrations caused by individual

sources produce similarly small changes in visibility impairment for
ambient conditions near the proposed standard level of either 30 dv or
28 dv. The second prong of the analysis addressed aspects of a PSD
cumulative impact analysis by exploring the relationship between the 3-
year design values for the primary and secondary 24-hour
PM2.5 standards and coincident design values for the
proposed PM2.5 visibility index standard based on recent air
quality data. This analysis showed that visibility generally decreases
when daily PM2.5 concentrations increase, and vice versa.
This analysis further explored the appropriateness of using a
demonstration that a source will not cause or contribute to a violation
of the 24-hour PM2.5 standards as a surrogate for a
demonstration that a source will not cause or contribute to a violation
of the proposed secondary PM2.5 visibility index standard.
The Kelly, et al. (2012) analysis was based on 2008 to 2010 air quality
data and on the proposed retention of the 24-hour PM2.5
standards with a level of 35 [micro]g/m\3\ in conjunction with a 98th
percentile form (sections III.F and IV.F) and the proposed secondary
PM2.5 visibility index standard with a level of either 30 dv
or 28 dv in conjunction with 24-hour averaging time and a 90th
percentile form (see section VI.F).\221\ This analysis indicated that
all or nearly all areas in attainment of the 24-hour PM2.5
standards would also likely be in attainment of the proposed secondary
PM2.5 visibility index standard.
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    \221\ As identified in section IX.E above, the relationships
between design values characterized in the Kelly, et al. (2012)
analysis and summarized here are dependent upon the specific level
and form of each of these standards.
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    The EPA believes that this technical analysis is robust and will
have broad national application. Based on this technical analysis, the
EPA currently believes that there is sufficient evidence that, for the
purposes of making a demonstration under the PSD program that a new or
modified source will not cause or contribute to a violation of the
proposed secondary 24-hour PM2.5 visibility index NAAQS, a
demonstration that the source will not cause or contribute to a
violation of the mass-based 24-hour PM2.5 NAAQS serves as a
suitable surrogate. As such, many or all sources undergoing PSD review
for PM2.5 would be able to rely upon their analysis
demonstrating that they will not cause or contribute to a violation of
the mass-based 24-hour PM2.5 NAAQS to also demonstrate that
they will not cause or contribute to a violation of the proposed
secondary PM2.5 visibility index NAAQS, if finalized. The
described surrogate approach would thus serve to overcome the technical
challenges discussed above and minimize otherwise burdensome and costly
air quality analyses associated with individual sources being required
to perform separate and distinct analyses with regard to the proposed
secondary PM2.5 visibility index standard. The EPA believes
this surrogacy approach is appropriate to fulfill PSD requirements for
individual sources in PSD areas, which, by definition, will not have
been designated as nonattainment for the PM2.5 visibility
index NAAQS. However, our proposed surrogacy approach for PSD should
not be construed as a proposal to use a surrogacy approach for
designating nonattainment areas or for implementing programs to attain
the visibility index NAAQS in those areas.
    The surrogacy approach is not intended to replace or otherwise
undermine the validity of the analytical techniques employed for air
quality related value (AQRV) assessments, including visibility,
required under 40 CFR 51.166(p) and 40 CFR 52.21(p). The federal land
managers (FLM)--federal officials with direct responsibility for
management of Federal Class I parks and wilderness areas--have an
affirmative responsibility to protect the AQRVs of such lands, and to
provide the appropriate procedures and analysis techniques for
assessing AQRVs (Appendix W to 40 CFR part 51, Sections 6.1(b) and
6.2.3(a)). The FLMs have developed specific modeling approaches for
AQRV assessments that are not specifically governed under the
requirements set forth in 40 CFR 51.166(l)(1) and 40 CFR 52.21(l)(1),
thus the surrogacy approach is not applicable to the AQRV assessments
under the PSD program.
    The surrogate approach could be incorporated into the PSD program
in any of three alternative ways. First, the decision as to whether the
surrogate approach is adequate could be handled on a case-by-case basis
in consultation with the permitting authority, similar to the existing
consultation process under the EPA's Guideline on Air Quality Models
for ozone and secondary PM2.5 impacts (40 CFR part 51,
appendix W, section 5.2.1.c), with no presumption regarding its
adequacy. Second, the EPA could establish a rebuttable presumption that
the surrogate approach is applicable for all permits through either
guidance or a notice-and-comment rulemaking. In either the first or
second alternative, there would be a possibility that reliance on a
surrogate-based demonstration could be subjected to challenge for any
particular permit analysis. Third, the EPA could establish that the
surrogate approach is applicable for all permits, also through a
notice-and-comment rulemaking. The EPA seeks comment on all of the
identified issues and proposed alternative implementation mechanisms
associated with the proposed surrogate approach. It is the Agency's
intention to issue either guidance or new regulatory provisions as just
described for a surrogacy approach by the time any final revisions to
the PM NAAQS become effective, so that sources seeking permits will not
be unnecessarily delayed.
    While noting the importance of the surrogacy approach as an
essential initial strategy due to limitations on data and analytical
tools, the EPA also notes that when a technically robust surrogate
relationship exists there may not be a need to apply an end date for
the use of a surrogacy approach. Without an end date, PSD applicants
would always have the option of relying upon such a demonstration if
they would so choose. This would offer long-term benefits in terms of
simplification and resource savings for applicants and reviewing
authorities. Accordingly, based on the technical analysis for the
standards analyzed (Kelly, et al, 2012) which supports the surrogacy
approach for demonstrating that a source will not cause or contribute
to a violation of the proposed secondary PM2.5 visibility
index NAAQS, the EPA may determine that it is not necessary to announce
an end date for using it. The EPA invites comment on this aspect of the
proposal as well.
    For context, the EPA notes that with regard to sources being
required to demonstrate that they would not cause or contribute to a
violation of the 1997 PM2.5 NAAQS, the EPA has previously
issued an interim policy (Seitz, 1997). Under the 1997 policy, which is
no longer in effect,\222\ the EPA stated that demonstrating compliance
with the NSR requirements for controlling PM10 emissions and
for analyzing impacts on PM10 air quality could be used to
demonstrate compliance with the PM2.5 NSR requirements. This
approach was designed to control PM2.5 emissions and protect
PM2.5 air quality until certain technical difficulties
concerning PM2.5 were resolved. At that time, however, we
did not support the policy with any technical analysis to show how a
demonstration of compliance with the PM10 NAAQS would
satisfy the PM2.5

requirements and support the issuance of a PSD permit. Consequently,
the EPA later concluded that, in keeping with numerous court opinions
regarding the use of surrogates, PSD applicants and reviewing
authorities seeking to rely specifically on the 1997 PM10
Surrogate Policy should consider certain overarching legal principles,
including that a surrogate may be used only after it has been shown to
be reasonable (such as where the surrogate is a reasonable proxy for
the pollutant or has a predictable correlation to the pollutant) and
that the relationship between the regulated pollutant and the surrogate
pollutant can be shown to apply in the specific instance where an
applicant or reviewing authority seeks to rely upon it. In keeping with
these principles, the Agency believes that the surrogate approach now
being proposed for use in demonstrating that a source will not cause or
contribute to a violation of the proposed secondary PM2.5
visibility index NAAQS is supported by a robust technical analysis. The
EPA invites comment on this analysis, which is provided in the docket
for this action.
---------------------------------------------------------------------------

    \222\ The 1997 PM10 Surrogate Policy formally ended
on May 16, 2011. See 76 FR 28646 (May 18, 2011).
---------------------------------------------------------------------------

    The EPA notes that the analysis supporting the surrogacy approach
for the PSD program is distinct from and serves a different purpose
than the analyses conducted to inform the Administrator's proposed
conclusion on the appropriate indicator for a standard intended to
protect against PM-related visibility impairment. As discussed in
section VI.A above, the EPA has long recognized that the determination
of a single, appropriate national level for a secondary standard to
address PM-related visibility impairment is complicated by regional
differences in several factors that influence visibility, such as
background and current PM2.5 concentrations,
PM2.5 composition, and average relative humidity. Variations
in these factors across regions could thus result in situations where
attaining an appropriately protective concentration of fine particles
in one region might or might not provide the appropriate degree of
protection in a different region. Although the analysis upon which the
surrogacy approach is based (Kelly, et al., 2012) generally shows that
daily PM2.5 visibility index values decrease when daily
PM2.5 mass concentrations decrease, and vice versa, there is
nonetheless considerable variability in that relationship across the
range of ambient fine particle concentrations. As a result, as
discussed in section VI.D.1.d above, the Administrator provisionally
concludes that a calculated PM2.5 light extinction indicator
is an appropriate indicator to replace the current PM2.5
mass indicator and that such an indicator would afford a relatively
high degree of uniformity of visual air quality protection in areas
across the country by virtue of directly incorporating the effects of
differences in PM2.5 composition and relative humidity
across the country.
d. PSD Screening Provisions: Significant Emissions Rates, Significant
Impact Levels, and Significant Modeling Concentration
    The EPA has historically allowed the use of screening tools to help
facilitate the implementation of the NSR program by reducing the permit
applicant's burden and streamlining the permitting process for
circumstances where emissions or concentrations could be considered de
minimis. These screening tools, which all provide de minimis thresholds
of some kind, include a significant emissions rate (SER), significant
impact levels (SILs), and a significant monitoring concentration (SMC).
The EPA promulgated a SER for PM2.5 in the 2008 final rule
on NSR implementation as part of the first phase of NSR amendments to
address PM2.5 (74 FR 28333, May 16, 2008). The
PM2.5 SER is used to determine whether any proposed major
stationary source or major modification will emit sufficient amounts of
PM2.5 to require review under the PSD program.\223\ Under
the terms of the existing EPA regulations, the applicable SER for
PM2.5 is 10 tpy of direct PM2.5 emissions
(including condensable PM) and, for precursors, 40 tpy of
SO2 and 40 tpy of NOX emissions. 40 CFR
51.166(b)(23); 40 CFR 52.21(b)(23). This SER applies to permitting
requirements based on both the annual and 24-hour PM2.5
NAAQS. The SERs are pollutant-specific but not specific to the
averaging time of any NAAQS for a particular pollutant. At this time,
the EPA is not proposing any change to the existing PM2.5
SER as a result of the proposed revisions to the primary annual
PM2.5 NAAQS and the proposed secondary PM2.5
visibility index NAAQS. However, the EPA intends to consider this issue
in a subsequent rulemaking that will specifically address various PSD
implementation issues that are being described herein. The EPA will
solicit comment on any proposed changes to the SERs for
PM2.5 and its precursors at that time, but also invites
preliminary suggestions at this time that we may consider in developing
that proposed rulemaking. Until any rulemaking to amend existing
regulations is completed, permitting decisions should continue to be
based on the SERs for PM2.5 and its precursors in existing
regulations.
---------------------------------------------------------------------------

    \223\ The PSD rules provide that a source that would emit major
amounts of any regulated NSR pollutant must undergo review for that
pollutant as well as any other regulated NSR pollutant that the
source would emit in significant amounts.
---------------------------------------------------------------------------

    Once it is determined that the proposed new source or modification
is significant for PM2.5, the permit applicant must complete
an air quality analysis. The SIL helps to determine the scope of the
required air quality analysis that must be carried out in order to
demonstrate that the source's emissions will not cause or contribute to
a violation of any NAAQS or increment. The EPA promulgated SILs for
PM2.5 in 2010 under a final rule that established
increments, SILs, and SMC for PM2.5 (75 FR 64890 to 64894,
October 20, 2010). A separate PM2.5 SIL is defined for each
averaging period for which PM2.5 NAAQS and increments
currently exist, as well as for each of the three area classifications,
i.e., Class I, II and III, that Congress established in the CAA for PSD
purposes.
    Historically, sources have been allowed to model their proposed
emissions increase to predict ambient impacts associated with that
emissions increase, and to compare this predicted ambient concentration
of PM2.5 to the applicable SIL, which is also expressed as
an ambient PM2.5 concentration over a prescribed averaging
time consistent with the NAAQS and increments. At this time, the EPA is
not proposing to revise the annual SIL for PM2.5 as a result
of the proposed revision to the primary annual PM2.5 NAAQS.
However, the EPA intends to review this issue and will consider any
potential need to revise the existing SIL in a separate rulemaking
addressing PSD implementation issues. The EPA welcomes preliminary
comments concerning this issue, but will also provide an additional
opportunity for comments at a later date in the event that a subsequent
proposal is made to revise the annual PM2.5 SIL.
    While the proposed secondary PM2.5 visibility index
NAAQS is a 24-hour standard for which no PM2.5 SIL is
currently defined, there is a question as to whether the existing 24-
hour PM2.5 SIL, expressed on a PM2.5 mass basis
([micro]g/m\3\), would be appropriate for this proposed secondary
NAAQS, expressed in terms of a PM2.5 visibility index. As
discussed in section IX.F.1.c above, the EPA conducted an analysis to
evaluate whether an individual source's impact resulting in a small
increase in PM2.5 concentration would produce a comparably
small increase in visibility impairment (Kelly et al., 2012). The

analysis indicates that small increases in PM2.5
concentrations caused by individual sources produce similarly small
changes in visibility impairment for ambient conditions near the
proposed standard level of either 30 dv or 28 dv.
    The EPA is not proposing any possible alternatives to the existing
24-hour PM2.5 SIL in this proposed rule, but instead intends
to issue a separate rulemaking to assess this and other related PSD
implementation issues. The EPA also wishes to note that the current
PM2.5 SILs are the subject of a petition that challenges the
EPA's legal authority under the CAA to develop and implement those
SILs, and also alleges that the existing PM2.5 SILs have not
been adequately demonstrated to represent de minimis values. Sierra
Club v. EPA, No. 10-1413 (D.C. Circuit filed December 17, 2010). In the
course of this litigation, the EPA has recognized the need to correct
the text of two PM2.5 SILs provisions in the regulations,
and the EPA has asked the court to vacate those provisions so that the
EPA may correct them. However, the EPA does not believe this corrective
action would preclude use of the PM2.5 SILs in the interim,
and the EPA intends to provide guidance on continued use of the
PM2.5 SILs (in a manner consistent with principles
articulated by the EPA in the rulemaking and litigation) pending this
correction of the regulatory text. The proposed revised primary annual
PM2.5 NAAQS and the proposed secondary PM2.5
visibility index NAAQS do not affect the continued used of the
PM2.5 SILs in accordance with the forthcoming guidance
described above. As a separate matter, the EPA intends to consider the
need for a new SIL specifically for implementing any secondary
PM2.5 visibility index NAAQS under the PSD program. In the
event that we do proceed, the EPA now welcomes preliminary comments as
to how such a SIL could be developed. The EPA will also provide an
additional opportunity for comments at a later date in the event that a
subsequent proposal is made to establish a separate SIL for the
secondary PM2.5 visibility index NAAQS, if such a secondary
NAAQS is finalized.
    Finally, the SMC, also measured as an ambient pollutant
concentration ([micro]g/m\3\), is a screening tool used to determine
whether it may be appropriate to exempt a proposed source from the
requirement to collect pre-construction ambient monitoring data as part
of the required air quality analysis for a particular pollutant. The
EPA promulgated the existing SMC for PM2.5 in 2010 on the
basis of the defined minimum detection limit for PM2.5 and
the current information at that time concerning the physical
capabilities of the PM2.5 FRM samplers. In that rulemaking,
the EPA addressed uncertainties introduced into the measurement of
PM2.5 due to variability in the mechanical performance of
the PM2.5 samplers and micro-gravimetric analytical balances
that weigh filter samples. In a future NSR implementation rulemaking
that will follow this rulemaking, the EPA intends to evaluate the types
of additional ambient data, if any, that may need to be collected by a
proposed source concerning the proposed secondary PM2.5
visibility index NAAQS, and the feasibility of individual sources being
required to gather such additional information. The EPA welcomes
preliminary comments concerning this issue, but will provide additional
opportunity for comment when a subsequent NSR implementation rulemaking
is proposed concerning the proposed revisions to the PM NAAQS.
e. PSD Increments
    Section 166(a) of the CAA requires the EPA to promulgate
``regulations to prevent the significant deterioration of air quality''
for pollutants covered by the NAAQS. Among other things, the EPA has
implemented this requirement through promulgation of PSD increments.
The EPA promulgated PM2.5 increments in 2010 to prevent
significant air quality deterioration with regard to the primary and
secondary annual and 24-hour PM2.5 NAAQS \224\ (75 FR 64864,
October 20, 2010). The proposed revision to the primary annual
PM2.5 NAAQS raises the question of whether the EPA should
consider revising the annual PM2.5 increments. Similarly,
the EPA's proposed action to establish a distinct secondary
PM2.5 visibility index NAAQS raises the question of whether
revisions to the PM2.5 increments are appropriate to address
public welfare considerations protected by the proposed secondary
standard.
---------------------------------------------------------------------------

    \224\ The primary and secondary NAAQS for PM2.5 have
been the same up until this time where EPA is proposing a distinct
secondary NAAQS for PM-related visibility impairment.
---------------------------------------------------------------------------

    In this proposal, the EPA is not proposing to revise the
PM2.5 increments. The EPA will consider whether it is
appropriate to propose such an action in the future, and if so, would
undertake the necessary rulemaking. The EPA invites preliminary
comments at this time on such a need, and on issues we should consider
if we undertake a rule to revise the PM2.5 increments. In
the meantime, the current PM2.5 increments remain in effect,
and PSD permitting should continue pursuant to the current increments,
with a minimum of disruption to the permitting process when the revised
NAAQS take effect.
2. Nonattainment New Source Review
    The requirements under part D of the CAA pertain to the
preconstruction review and permitting requirements for new major
stationary sources and major modifications locating in areas designated
``nonattainment'' for a particular pollutant. Those requirements are
commonly referred to as the NNSR program. The EPA regulations for the
NNSR program are contained at 40 CFR 51.165, 52.24 and part 51,
appendix S.
    For NNSR, ``major stationary source'' is generally defined as a
source with the potential to emit at least 100 tpy or more of a
pollutant for which an area has been designated ``nonattainment.''
Thus, the NNSR program applies to pollutants for which the EPA has
promulgated NAAQS. Because the EPA has defined the PM NAAQS, and has
established area designations for PM, in terms of two separate
indicators--PM10 and PM2.5--each indicator is
regulated separately for purposes of NNSR applicability. That is, for
PM10, a ``major stationary source'' for NNSR applicability
generally is a source that is located in a PM10
nonattainment area and has the potential to emit at least 100 tpy of
PM10 emissions.\225\ For PM2.5, a ``major
stationary source'' for NNSR applicability is a source that is located
in a PM2.5 nonattainment area and has the potential to emit
at least 100 tpy of direct PM2.5 (``PM2.5
emissions'') or a precursor of PM2.5.
---------------------------------------------------------------------------

    \225\ In some cases, however, the CAA and the EPA's regulations
define ``major stationary source'' for nonattainment area NSR in
terms of a lower emissions rate dependent on the pollutant. For
PM10, for example, a source having the potential to emit
at least 70 tpy of PM10 is considered ``major'' if the
source is located in a nonattainment area classified as a ``Serious
Area.''
---------------------------------------------------------------------------

    For a major modification, the NNSR rules rely upon SERs described
previously in the PSD discussion in section IX.F.1. For NNSR, a major
modification is a physical change or a change in the method of
operation of an existing stationary source that is major for the
nonattainment pollutant and that results in a significant net emissions
increase of that nonattainment pollutant. As described earlier, the EPA
will be evaluating the existing SERs for PM2.5 and
PM2.5 precursors, and will determine whether there is any
basis for proposing changes to the existing values. Any decision to
propose

changing the existing SERs in a future rulemaking would also apply to
their use in the NNSR program requirements.
    The EPA has designated nonattainment areas for the existing primary
annual and 24-hour PM2.5 NAAQS independently, and the EPA
also approves redesignations to attainment separately for the two
averaging periods. Thus, an area may be nonattainment for the annual
standard and unclassifiable/attainment or attainment for the 24-hour
standard. While no formal policy has yet been developed to address this
situation, the EPA presently believes that it is reasonable to require
that only NNSR (and not PSD) applies for PM2.5 in any area
that is nonattainment for either averaging period.\226\ Looking
forward, the EPA proposes that areas would be designated for a proposed
secondary PM2.5 visibility index NAAQS independently of
designations for the mass-based annual and 24-hour PM2.5
NAAQS. Accordingly, the EPA intends to address this issue in a future
NSR rulemaking, but invites comments now on whether it is appropriate
to apply the NNSR program requirements for any pollutant that is
designated nonattainment for at least one averaging period or at least
one primary or secondary NAAQS for a particular pollutant.
---------------------------------------------------------------------------

    \226\ However, transportation conformity requirements discussed
in section IX.G below are dependent upon the averaging period(s) for
which an area is designated nonattainment.
---------------------------------------------------------------------------

    New major stationary sources or major modifications based on
PM2.5 emissions (or emissions of a PM2.5
precursor) in a PM2.5 nonattainment area, must install
technology that meets the lowest achievable emission rate (LAER);
secure appropriate emissions reductions to offset the proposed
emissions increases; and perform other analyses as required under
section 173 of the CAA. Following the promulgation of any revised NAAQS
for PM2.5, some new nonattainment areas for PM2.5
may result. Where a state does not have any NNSR program or the current
NNSR program does not apply to PM2.5, that state will be
required to submit the necessary SIP revisions to ensure that new major
stationary sources and major modifications for PM2.5 undergo
preconstruction review pursuant to the NNSR program. Under section
172(b) of the CAA, the Administrator may provide states up to 3 years
from the effective date of nonattainment area designations to submit
the necessary SIP revisions meeting the applicable NNSR requirements.
Nevertheless, permits issued to sources in nonattainment areas must
satisfy the applicable NNSR requirements as of the effective date of
the nonattainment designation; therefore states lacking the appropriate
NNSR program requirements at that time will be allowed to issue such
permits during the SIP revision period in accordance with the
applicable nonattainment permitting requirements contained in the
Emissions Offset Interpretative Ruling at 40 CFR part 51, appendix S,
which would apply to the revised PM NAAQS upon their effective date.
The EPA is not proposing any type of PM2.5 grandfathering
provision at this time for purposes of NNSR. The timetable for adopting
new provisions under the state NNSR program will not apply with regard
to the revised NAAQS for PM2.5 until such time that an area
is designated nonattainment for a particular standard. Further
consideration of the need for a grandfathering provision for purposes
of NNSR for the revised NAAQS for PM2.5 will be made and
addressed in the future, as appropriate.

G. Transportation Conformity Program

    Transportation conformity is required under CAA section 176(c) to
ensure that transportation plans, transportation improvement programs
(TIPs) and federally supported highway and transit projects will not
cause new air quality violations, worsen existing violations, or delay
timely attainment of the relevant NAAQS or interim reductions and
milestones. Transportation conformity applies to areas that are
designated nonattainment and maintenance for transportation-related
criteria pollutants: Carbon monoxide, ozone, NO2, and
PM2.5, and PM10. Transportation conformity for
any revised NAAQS for PM2.5 does not apply until 1 year
after the effective date of the nonattainment designation for that
NAAQS (See CAA section 176(c)(6) and 40 CFR 93.102(d)). The EPA's
Transportation Conformity Rule (40 CFR part 51, subpart T, and 40 CFR
part 93, subpart A) establishes the criteria and procedures for
determining whether transportation activities conform to the SIP. The
EPA is not proposing changes to the transportation conformity rule in
this proposed rulemaking. The EPA notes that the transportation
conformity rule already addresses the PM2.5 and
PM10 NAAQS. However, in the future, the EPA will review the
need to issue or revise guidance describing how the current conformity
rule applies in nonattainment and maintenance areas for any revised
primary or distinct secondary PM NAAQS, as needed.
    As discussed in section VIII above, the EPA is proposing certain
clarifying changes to PM2.5 air quality monitoring
regulations These proposed changes are designed to align different
elements of the monitoring regulations for consistency, which will help
facilitate the interpretation of modeling results from quantitative
PM2.5 conformity hot-spot analyses for the annual standards
by clarifying which receptors are comparable to the NAAQS.
    If the EPA finalizes these changes to the monitoring regulations,
the EPA will update its guidance on quantitative PM2.5 hot-
spot analyses as appropriate to make it consistent with the revised
monitoring requirements (U.S. EPA, 2010j). If the proposed revisions to
the monitoring requirements are finalized, the EPA intends that the
current quantitative PM2.5 hot spot guidance would continue
to apply to any quantitative PM2.5 hot-spot analysis that
was begun before the effective date of these proposed revisions to the
monitoring regulations. Revised guidance on receptors to be compared to
the annual PM2.5 standards for quantitative PM2.5
hot-spot analyses would apply to any quantitative PM2.5 hot-
spot analysis begun after the effective date of the revised monitoring
regulations. Nonattainment and maintenance areas are encouraged to use
their interagency consultation processes to determine whether an
analysis for a given project was started before the effective date of
changes to the monitoring requirements. Applying the current guidance
regarding whether or not a receptor can be compared to the annual
PM2.5 NAAQS to analyses that had begun before the effective
date of changes to the monitoring regulations is consistent with how
the conformity rule and guidance address the transitional period for
new emissions factor models or local planning assumptions (40 CFR
93.110(a) and 93.111(b) and (c)). In both of those cases, analyses
begun before the new model or data became available can be completed
using the data and/or model that were available when the analyses
began. The EPA allows this in order to conserve state resources by not
making transportation planning agencies redo analyses simply because a
model has been revised, new data have become available, or in this
case, the EPA has revised its regulations for PM2.5
monitoring.

H. General Conformity Program

    General conformity is required by CAA section 176(c). This section
requires that federal agencies do not adopt, accept, approve, or fund
activities that are not consistent with state air quality goals.
General conformity applies to any federal action

(e.g., funding, licensing, permitting, or approving), other than
projects that are Federal Highway Administration (FHWA)/Federal Transit
Administration (FTA) projects as defined in 40 CFR 93.101 (which are
covered under transportation conformity described above), if the action
takes place in a nonattainment or maintenance area for ozone, PM,
NO2, carbon monoxide, lead, or SO2. General
conformity also applies to a federal highway and transit project if it
does not involve either Title 23 or 49 funding, but does involve FHWA
or FTA approval such as is required for a connection to an Interstate
highway or for a deviation from applicable design standards per 40 CFR
93.101. (The FHWA and FTA actions described here as not subject to
general conformity are subject to transportation conformity.) General
conformity for any revised PM NAAQS would not apply until 1 year after
the effective date of a nonattainment designation for that NAAQS. The
EPA's General Conformity Rule (40 CFR 93.150 to 93.165) establishes the
criteria and procedures for determining if a federal action conforms to
the SIP. With respect to any revision to the primary or secondary
standards, a federal agency would be expected to continue to estimate
emissions for conformity analyses in the same manner as they are
estimated for conformity analyses for the current PM NAAQS. EPA's
existing general conformity regulations include the basic requirement
that a federal agency's general conformity analysis be based on the
latest and most accurate emission estimation techniques available (40
CFR 93.159(b)), and EPA would expect that this same principle would be
followed for analyses needed with respect to any revised PM NAAQS. When
updated and improved emissions estimation techniques become available,
EPA would expect the federal agency to use these techniques. The EPA is
not proposing changes to the general conformity rule in this proposed
rulemaking. The general conformity rule already addresses the
PM2.5 and PM10 NAAQS. The EPA will review the
need to issue guidance describing how the current conformity rule
applies in nonattainment and maintenance areas for the final revised
primary and secondary PM NAAQS.

X. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    Under section 3(f)(1) of Executive Order 12866 (58 FR 51735,
October 4, 1993), this action is an ``economically significant
regulatory action'' because it is likely to have an annual effect on
the economy of $100 million or more. Accordingly, the EPA submitted
this action to the Office of Management and Budget (OMB) for review
under Executive Orders 12866 and 13563 (76 FR 3821, January 21, 2011),
and any changes made in response to OMB recommendations have been
documented in the docket for this action.
    In addition, the EPA prepared an analysis of the potential costs
and benefits associated with this action. This analysis is contained in
Regulatory Impact Analysis for the Proposed Revisions to the National
Ambient Air Quality Standards for Particulate Matter, EPA 452/R-12-003.
A copy of the analysis is available in Docket No. EPA-HQ-OAR-2010-0955.
    The estimates in the RIA are associated with alternative levels (in
[mu]g/m\3\) of the primary annual/24-hour PM2.5 standards
including: 13/35, 12/35, 11/35, and 11/30. Table 4 provides a summary
of the estimated costs, monetized benefits, and net benefits associated
with full attainment of these alternative standards.

                                            Table 4--Total Costs, Monetized Benefits and Net Benefits in 2020 a (millions of 2006$) b Full Attainment
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Total costs                             Monetized benefits \c\                                               Net benefits \c\
 Alternate PM2.5 Standards (annual/ ------------------------------------------------------------------------------------------------------------------------------------------------------------
      24-hour, in [mu]g/m\3\)        3% Discount  7% Discount
                                         rate         rate             3% Discount rate                 7% Discount rate               3% Discount rate \d\              7% Discount rate
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
13/35..............................         $2.9         $2.9  $88 to $220                      $79 to $200                      $85 to $220                      $76 to $200
12/35..............................           69           69  $2,300 to $5,900                 $2,100 to $5,400                 $2,300 to $5,900                 $2,000 to $5,300
11/35..............................          270          270  $9,200 to $23,000                $8,300 to $21,000                $8,900 to $2300                  $8,000 to $21,000
11/30..............................          390          390  $14,000 to $36,000               $13,000 to $33,000               $14,000 to $36,000               $13,000 to $33,000
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Values are rounded to two significant figures.
\b\ Using a 2010$ year increases estimated costs and benefits by approximately 8%.
\c\ The reduction in premature death each year accounts for over 90 percent of total monetized benefits. Mortality risk valuation assumes discounting over the SAB-recommended 20-year segmented
  lag structure. Not all possible benefits or disbenefits are quantified and monetized in this analysis. B is the sum of all unquantified benefits. Data limitations prevented us from
  quantifying these endpoints, and as such, these benefits are inherently more uncertain than those benefits that we were able to quantify.
\d\ Due to data limitations, we were unable to discount compliance costs for all sectors at 3%. As a result, the net benefit calculations at 3% were computed by subtracting the monetized
  benefits at 3% minus the costs at 7%.

B. Paperwork Reduction Act

    This action does not impose an information collection burden under
the provisions of the Paperwork Reduction Act, 44 U.S.S. 3501 et seq.
Burden is defined at 5 CFR 1320.3(b). There are no information
collection requirements directly associated with revisions to a NAAQS
under section 109 of the CAA.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the agency certifies that the
rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations, and small governmental jurisdictions.
    For purposes of assessing the impacts of this rule on small
entities, small entity is defined as: (1) A small business that is a
small industrial entity as defined by the Small Business
Administration's (SBA) regulations at 13 CFR 121.201; (2) a small
governmental jurisdiction that is a government of a city, county, town,
school district or special district with a population of less than
50,000; and (3) a small organization that is any not-for-profit
enterprise which is independently owned and operated and is not
dominant in its field.

    After considering the economic impacts of this proposed rule on
small entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities. This
proposed rule will not impose any requirements on small entities.
Rather, this rule establishes national standards for allowable
concentrations of particulate matter in ambient air as required by
section 109 of the CAA. See also American Trucking Associations v. EPA.
175 F.3d at 1044-45 (NAAQS do not have significant impacts upon small
entities because NAAQS themselves impose no regulations upon small
entities). We continue to be interested in the potential impacts of the
proposed rule on small entities and welcome comments on issues related
to such impacts.

D. Unfunded Mandates Reform Act

    This action contains no Federal mandates under the provisions of
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), 2 U.S.C.
1531-1538 for state, local, or tribal governments or the private
sector. The action imposes no enforceable duty on any state, local or
tribal governments or the private sector. Therefore, this action is not
subject to the requirements of sections 202 or 205 of the UMRA.
    This action is also not subject to the requirements section 205 of
the UMRA because it contains no regulatory requirements that might
significantly or uniquely affect small governments. This action imposes
no new expenditure or enforceable duty on any state, local, or tribal
governments or the private sector, and the EPA has determined that this
rule contains no regulatory requirements that might significantly or
uniquely affect small governments.
    Furthermore, in setting a NAAQS, the EPA cannot consider the
economic or technological feasibility of attaining ambient air quality
standards, although such factors may be considered to a degree in the
development of state plans to implement the standards. See also
American Trucking Associations v. EPA, 175 F. 3d at 1043 (noting that
because the EPA is precluded from considering costs of implementation
in establishing NAAQS, preparation of a Regulatory Impact Analysis
pursuant to the Unfunded Mandates Reform Act would not furnish any
information which the court could consider in reviewing the NAAQS). The
EPA acknowledges, however, that any corresponding revisions to
associated SIP requirements and air quality surveillance requirements,
40 CFR part 51 and 40 CFR part 58, respectively, might result in such
effects. Accordingly, the EPA will address, as appropriate, unfunded
mandates if and when it proposes any revisions to 40 CFR parts 51 or
58.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government, as
specified in Executive Order 13132. The rule does not alter the
relationship between the Federal government and the states regarding
the establishment and implementation of air quality improvement
programs as codified in the CAA. Under section 109 of the CAA, the EPA
is mandated to establish and review NAAQS; however, CAA section 116
preserves the rights of states to establish more stringent requirements
if deemed necessary by a state. Furthermore, this proposed rule does
not impact CAA section 107 which establishes that the states have
primary responsibility for implementation of the NAAQS. Finally, as
noted in section D (above) on UMRA, this rule does not impose
significant costs on state, local, or Tribal governments or the private
sector. Thus, Executive Order 13132 does not apply to this action.
    However, as also noted in section D (above) on UMRA, the EPA
recognizes that states will have a substantial interest in this rule
and any corresponding revisions to associated air quality surveillance
requirements, 40 CFR part 58. Therefore, in the spirit of Executive
Order 13132, and consistent with EPA policy to promote communications
between the EPA and state and local governments, the EPA specifically
solicits comment on this proposed rule from state and local officials.

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

    The action does not have tribal implications, as specified in
Executive Order 13175 (65 FR 67249, November 9, 2000). It does not have
a substantial direct effect on one or more Indian Tribes, since Tribes
are not obligated to adopt or implement any NAAQS. The Tribal Authority
Rule gives Tribes the opportunity to develop and implement CAA programs
such as the PM NAAQS, but it leaves to the discretion of the Tribe
whether to develop these programs and which programs, or appropriate
elements of a program, they will adopt. Thus, Executive Order 13175
does not apply to this rule.
    Although Executive Order 13175 does not apply to this rule, the EPA
consulted with tribal officials or other representatives of tribal
governments in developing this action.
    The EPA specifically solicits additional comments on this proposed
rule from tribal officials.

G. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks

    This action is subject to Executive Order 13045 (62 FR 19885, April
23, 1997) because it is an economically significant regulatory action
as defined by Executive Order 12866, and the EPA believes that the
environmental health or safety risk addressed by this action may have a
disproportionate effect on children. Accordingly, we have evaluated the
environmental health or safety effects of PM exposures on children. The
protection offered by these standards may be especially important for
children because childhood represents a lifestage associated with
increased susceptibility to PM-related health effects. Because children
have been identified as a susceptible population, we have carefully
evaluated the environmental health effects of exposure to PM pollution
among children. Discussions of the results of the evaluation of the
scientific evidence and policy considerations pertaining to children
are contained in sections III.B, III.D, IV.B, and IV.C of this
preamble. A listing of documents that contain the evaluation of
scientific evidence and policy considerations that pertain to children
is found in the section on Children's Environmental Health in the
Supplementary Information section of this preamble, and a copy of all
documents have been placed in the public docket for this action.
    The public is invited to submit comments or identify peer-reviewed
studies and data that assess effects of early life exposure to PM.

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

    This action is not a ``significant energy action'' as defined in
Executive Order 13211, (66 FR 28355, May 22, 2001) because it is not
likely to have a significant adverse effect on the supply,
distribution, or use of energy. The purpose of this action concerns the
review of the NAAQS for PM. The action does not prescribe specific
pollution control strategies by which these ambient standards will be
met.

Such strategies are developed by states on a case-by-case basis, and
the EPA cannot predict whether the control options selected by states
will include regulations on energy suppliers, distributors, or users.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law 104-113, section 12(d) (15 U.S.C. 272
note) directs the EPA to use voluntary consensus standards in its
regulatory activities unless to do so would be inconsistent with
applicable law or otherwise impractical. Voluntary consensus standards
are technical standards (e.g., materials specifications, test methods,
sampling procedures, and business practices) that are developed or
adopted by voluntary consensus standards bodies. The NTTAA directs the
EPA to provide Congress, through OMB, explanations when the Agency
decides not to use available and applicable voluntary consensus
standards.
    This proposed rulemaking involves technical standards for
environmental monitoring and measurement. Specifically, the EPA
proposes to retain the indicators for fine (PM2.5) and
coarse (PM10) particles. The indicator for fine particles is
measured using the Reference Method for the Determination of Fine
Particulate Matter as PM2.5 in the Atmosphere (appendix L to
40 CFR part 50), which is known as the PM2.5 FRM, and the
indicator for coarse particles is measured using the Reference Method
for the Determination of Particulate Matter as PM10 in the
Atmosphere (appendix J to 40 CFR part 50), which is known as the
PM10 FRM. The EPA also proposes to add a distinct secondary
standard for PM2.5 defined in terms of a calculated
PM2.5 light extinction indicator, which would use
PM2.5 mass species and relative humidity data to calculate
PM2.5 light extinction.
    To the extent feasible, the EPA employs a Performance-Based
Measurement System (PBMS), which does not require the use of specific,
prescribed analytic methods. The PBMS is defined as a set of processes
wherein the data quality needs, mandates or limitations of a program or
project are specified, and serve as criteria for selecting appropriate
methods to meet those needs in a cost-effective manner. It is intended
to be more flexible and cost effective for the regulated community; it
is also intended to encourage innovation in analytical technology and
improved data quality. Though the FRM defines the particular
specifications for ambient monitors, there is some variability with
regard to how monitors measure PM, depending on the type and size of PM
and environmental conditions. Therefore, it is not practically possible
to fully define the FRM in performance terms to account for this
variability. Nevertheless, our approach in the past has resulted in
multiple brands of monitors being approved as FRM for PM, and we expect
this to continue. Also, the FRMs described in 40 CFR part 50 and the
equivalency criteria described in 40 CFR part 53, constitute a
performance-based measurement system for PM, since methods that meet
the field testing and performance criteria can be approved as FEMs.
Since finalized in 2006 (71 FR, 61236, October 17, 2006) the new field
and performance criteria for approval of PM2.5 continuous
FEMs has resulted in the approval of six approved FEMs.\227\ In
summary, for measurement of PM2.5 and PM10, the
EPA relies on both FRMs and FEMs, with FEMs relying on a PBMS approach
for their approval. The EPA is not precluding the use of any other
method, whether it constitutes a voluntary consensus standard or not,
as long as it meets the specified performance criteria.
---------------------------------------------------------------------------

    \227\ A list of designated reference and equivalent methods is
available on EPA's Web site at: http://www.epa.gov/ttn/amtic/criteria.html.
---------------------------------------------------------------------------

    For the proposed secondary standard defined in terms of a
calculated PM2.5 light extinction indicator, the EPA
proposes to use existing monitoring technologies that are already
deployed in the CSN and IMPROVE monitoring programs as well as relative
humidity data from sensors already deployed at routine weather
stations. The sampling and analysis protocols in use in the CSN program
are the result of substantial input and recommendations from CASAC both
during their initial deployment about ten years ago, and during the
more recent transition to carbon sampling that is consistent with
IMPROVE protocols (Henderson 2005c). Monitoring agencies also played a
strong role in directing the sampling technologies used in the CSN.
During the first few years of implementing the CSN there were up to
four different sampling approaches used in the network. Over time as
monitoring agencies shared their experiences and data with each other,
several agencies shifted their network operations to the sampling
technology used today. By 2008, the EPA was working closely with all
remaining monitoring agencies to transition to the current CSN sampling
for ions and elements. All carbon sampling was fully transitioned to
the current method by October of 2009 for consistency with the IMPROVE
program. Therefore, while the current CSN sampling methods were not
developed or adopted by a voluntary consensus standard body, they are
the result of harmonizing the network by monitoring agency users and
EPA. The CSN network and methods are described in more detail in the
Policy Assessment (U.S. EPA, 2011a, Appendix B, section B.1.3).
    The EPA welcomes comments on this aspect of the proposed rulemaking
and, specifically, invites the public to identify potentially
applicable voluntary consensus standards for any of the proposed
indicators with an explanation as to why such standards should be used
in this regulation.

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

    Executive Order 12898 (59 FR 7629, February 16, 1994) establishes
federal executive policy on environmental justice. Its main provision
directs federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing, as appropriate, disproportionately high
and adverse human health or environmental effects of their programs,
policies, and activities on minority populations and low-income
populations in the United States.
    The EPA maintains an ongoing commitment to ensure environmental
justice for all people, regardless of race, color, national origin, or
income. Ensuring environmental justice means not only protecting human
health and the environment for everyone, but also ensuring that all
people are treated fairly and are given the opportunity to participate
meaningfully in the development, implementation, and enforcement of
environmental laws, regulations, and policies. The EPA has identified
potential disproportionately high and adverse effects on minority and/
or low-income populations from this proposed rule.
    The EPA has identified persons from lower socioeconomic strata as a
susceptible population for PM-related health effects. As a result, the
EPA has carefully evaluated the potential impacts on low-income and
minority populations as discussed in section III.E.3.a of this
preamble. The Agency expects this proposed rule would lead to the
establishment of uniform NAAQS for PM. The Integrated Science

Assessment and Policy Assessment contain the evaluation of the
scientific evidence and policy considerations that pertain to these
populations. These documents are available as described in the
Supplementary Information section of this preamble and copies of all
documents have been placed in the public docket for this action.
    The public is invited to submit comments or identify peer-reviewed
studies and data that assess effects of PM on low-income populations
and minority populations.

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