the situation adequately, and there would be no need for a CAA section
188(f) waiver. If the state determines that, even with the exclusion of
the event-influenced data, the waiver provisions of CAA section 188(f)
may also be applicable, then the EPA can evaluate that question based
on the remaining data that are representative for the area in question.
Given that section 188(f) has rarely been invoked, a state wishing to
pursue this

provision should work closely with its EPA Regional Office.
    c. Comments and Responses. Comments: Some commenters urged the EPA
to clarify the two-step approach. Some commenters recommended that the
EPA refrain from directing the sequence and allow states to decide
which of these provisions should apply in the specific circumstances
that they are addressing, consistent with the commenter's overall
recommendation that the EPA give states the maximum flexibility in
developing PM2.5 SIPs. Some commenters urged the EPA to
provide guidance to the states on when this two-step approach would be
appropriate, and when it would be inappropriate. Commenters did not
want implementation planning to follow the EPA's exceptional events
justification model in which there is great variability among the EPA
regions. Commenter encouraged the EPA to work to ensure that
PM2.5 implementation plan reviews are subject to similar
requirements in all EPA regions with clarifying language in the final
guidance to ensure some level of national consistency.
    Response: The EPA agrees with the first comment that, rather than
the EPA ``directing the sequence,'' the affected state and the
appropriate EPA regional office should discuss the scenario and the
affected data to determine whether the Exceptional Events Rule or CAA
section 188(f) is the most appropriate mechanism. This decision would
be made on a case-by-case basis considering the specific, relevant
facts. In most cases, if the monitored air quality data satisfy the
requirements of the Exceptional Events Rule, then applying these
provisions would likely provide additional regulatory flexibilities
beyond those that CAA section 188(f) would provide. However, regardless
of whether the data in question meet or do not meet the requirements of
the Exceptional Events Rule (e.g., because the exceptional events
definition is not met in that the data do not constitute an exceedance
or violation of the NAAQS or because other Exceptional Events rule
criteria are not met), the waiver provisions in CAA section 188(f)
could apply.
    The EPA recognizes the implementation challenges associated with
the 2007 Exceptional Events Rule and recently proposed revisions to
this rule to address certain substantive issues raised by state, local
and tribal co-regulators and other stakeholders since promulgation of
the rule and to increase the administrative efficiency of the
Exceptional Events Rule criteria and process (80 FR 72840, November 20,
2015). The public comment period on this rule closed on February 3,
2016. The EPA will consider timely comments provided to the Exceptional
Events Rule docket as we finalize the revisions to this rule.

B. Conformity Requirements

1. Requirements That Apply to Both Transportation Conformity and
General Conformity
    a. Background on Transportation and General Conformity. Conformity
is required under CAA section 176(c) to ensure that federal actions are
consistent with (``conform to'') the purpose of the SIP. Conformity to
the purpose of the SIP means that federal activities will not cause new
air quality violations, worsen existing violations, or delay timely
attainment of the relevant NAAQS or interim reductions and milestones.
Conformity applies to areas that are designated nonattainment, and
those nonattainment areas redesignated to attainment with a CAA section
175A maintenance plan after 1990 (``maintenance areas'').
    The EPA's Transportation Conformity Rule (40 CFR 51.390 and part
93, subpart A) establishes the criteria and procedures for determining
whether transportation activities conform to the SIP. These activities
include adopting, funding or approving transportation plans,
transportation improvement programs (TIPs) and federally supported
highway and transit projects. The EPA first promulgated the
Transportation Conformity Rule on November 24, 1993 (58 FR 62188), and
subsequently published several amendments. For example, the EPA
published a final rule on July 1, 2004 (69 FR 40004) that provided
conformity procedures for state and local agencies under the 1997
PM2.5 NAAQS, among other things. On May 6, 2005 (70 FR
24280) the EPA published a final rule that addressed transportation
conformity requirements for PM2.5 precursors.\244\ The EPA
published another final rule on March 24, 2010 (75 FR 14260) that
addressed additional requirements for the 2006 PM2.5 NAAQS.
Finally, the EPA published a final rule on March 14, 2012 (77 FR 14979)
that restructured portions of the transportation conformity rule so
that they would clearly apply to nonattainment and maintenance areas
for the new and revised NAAQS, including the 2012 PM2.5
NAAQS. All of these rules apply to the current PM2.5 NAAQS
including the 1997 PM2.5 NAAQS, the 2006 24-hour
PM2.5 NAAQS and the 2012 primary annual PM2.5
NAAQS and will apply to future PM2.5 NAAQS. For further
information on transportation conformity rulemakings, policy guidance
and outreach materials, see the EPA's Web site at http://www3.epa.gov/otaq/stateresources/transconf/index.htm. The EPA issued transportation
conformity guidance related to the implementation of the 2012 primary
annual PM2.5 NAAQS in November 2015. The guidance is
available at http://www3.epa.gov/otaq/stateresources/transconf/documents/420b15091.pdf.
---------------------------------------------------------------------------

    \244\ This final rule was not challenged, nor was it affected by
the January 2013 D.C. Circuit Court decision requiring the EPA to
implement the PM2.5 NAAQS pursuant to subpart 4 of the
CAA.
---------------------------------------------------------------------------

    With regard to general conformity, the EPA first promulgated
general conformity regulations in November 1993 (40 CFR part 51,
subpart W and 40 CFR part 93, subpart B). Subsequently, the EPA
finalized revisions to the general conformity regulations on April 5,
2010. (75 FR 17254-17279) The general conformity program ensures that
federal actions not covered by the transportation conformity rule will
not interfere with the SIP. General conformity also fosters
communications between federal agencies and state/local air quality
agencies, provides for public notification of and access to federal
agency conformity determinations and allows for air quality review of
individual federal actions. More information on the general conformity
program is available at www.epa.gov/airquality/genconform/.
    b. Conformity in the Proposed Rule. The EPA did not propose any
changes to the transportation conformity program as part of the current
action. Nevertheless, to provide clarity in applying those regulations,
the EPA is providing affected parties with information on when
conformity must be implemented after nonattainment areas are designated
for a new or revised PM2.5 NAAQS. At this time the EPA is
using the 2012 PM2.5 NAAQS as an example. The agency is also
discussing how it plans to make the transition from demonstrating
conformity for the 1997 annual PM2.5 NAAQS to the 2012
primary annual PM2.5 NAAQS because this transition is unique
in that the 1997 annual PM2.5 NAAQS was retained as a
secondary NAAQS. Finally, we proposed a change to the general
conformity rule that addresses de minimis levels that apply to federal
actions in PM2.5 areas. The information presented here is
consistent with existing conformity regulations and statutory
provisions that are not addressed by this PM2.5
implementation rulemaking. Affected parties would include state and
local transportation

and air quality agencies, metropolitan planning organizations (MPOs),
and all federal agencies including the U.S. Department of
Transportation, the U.S. Department of Defense, the U.S. Department of
Interior and the U.S. Department of Agriculture.
    c. Applicability of Transportation and General Conformity to Areas
Designated Nonattainment for the 2012 Primary Annual PM2.5
NAAQS. Transportation and general conformity apply 1 year after the
effective date of nonattainment designations for a new or revised
PM2.5 NAAQS including the 2012 primary annual
PM2.5 NAAQS, April 15, 2016. This is because CAA section
176(c)(6) provides a 1-year grace period from the effective date of
initial designations for any new NAAQS before transportation and
general conformity apply in areas newly designated nonattainment for a
specific pollutant and the NAAQS. With regard to general conformity,
the EPA's April 2010 revisions to its general conformity regulations
(see 75 FR 17277, April 5, 2010) apply the same 1-year grace period for
the purposes of general conformity.
    With regard to transportation conformity, the conformity grace
period applies to all areas designated nonattainment for a new or
revised PM2.5 NAAQS including the 2012 primary annual
PM2.5 NAAQS. The requirements differ depending on whether
the nonattainment area includes any part of an MPO area designated
under 23 U.S.C. 134 or is an isolated rural area. Within 1 year after
the effective date of the initial nonattainment designation for a given
pollutant and the NAAQS, the MPOs and DOT must make a transportation
conformity determination with regard to that pollutant and standard for
all of the metropolitan transportation plans and TIPs in the
nonattainment area. The conformity requirements for surrounding ``donut
areas,'' including the application of the 1-year conformity grace
period, are generally the same as those for metropolitan areas.\245\
For the purposes of the implementation of the 2012 PM2.5
NAAQS, MPOs and any adjacent donut areas in a 2012 PM2.5
nonattainment area must continue to meet conformity requirements during
the grace period for any other applicable NAAQS, including the 1997
annual PM2.5 NAAQS and the 2006 24-hour PM2.5
NAAQS. If, at the end of the grace period for the 2012 annual
PM2.5 NAAQS, the MPO and DOT have not made a transportation
plan and TIP conformity determination for that NAAQS, the area would be
in a conformity ``lapse.'' During a conformity lapse, only certain
projects can receive federal funding or approvals to proceed. The
practical impact of a conformity lapse will vary from area to area.
Finally, the 1-year conformity grace period also applies to project
level conformity determinations.
---------------------------------------------------------------------------

    \245\ For the purposes of transportation conformity, a ``donut''
area is the geographic area outside a metropolitan planning area
boundary, but inside a designated nonattainment or maintenance area
boundary that includes an MPO (40 CFR 93.101).
---------------------------------------------------------------------------

    Isolated rural nonattainment and maintenance areas are areas that
do not contain or are not part of an MPO (40 CFR 93.101).
Transportation conformity requirements for isolated rural nonattainment
and maintenance areas can be found at 40 CFR 93.109(g). The CAA section
176(c)(6) 1-year grace period for newly designated nonattainment areas
applies to isolated rural areas. Therefore, 1 year after the effective
date of the initial nonattainment designation for a given pollutant and
the NAAQS, conformity requirements with regard to that pollutant and
standard would apply in any nonattainment areas that are isolated rural
areas. Per the transportation conformity rule, an isolated rural area
would be required to make a transportation conformity determination
only at the point when an applicable transportation project needs
funding or approval. This project level conformity determination may
occur significantly after the 1-year grace period has ended. See the
EPA's transportation conformity guidance related to the implementation
of the 2012 primary annual PM2.5 NAAQS for further
information on how the EPA has implemented this conformity grace period
in metropolitan, donut and isolated rural areas. The guidance is
available at http://www3.epa.gov/otaq/stateresources/transconf/documents/420b15091.pdf.
    d. Applicability of Transportation and General Conformity With
Regard to the 1997 Annual PM2.5 NAAQS, Which was Retained as a
Secondary NAAQS. In the December 2012 PM NAAQS final rule, the EPA
established a new health-based primary annual PM2.5 NAAQS of
12.0 [mu]g/m\3\. In that same action the EPA retained the 1997 annual
PM2.5 NAAQS of 15.0 [mu]g/m\3\ as a secondary NAAQS to
protect against certain welfare effects. In the 1997 PM2.5
designations rule (70 FR 944), the EPA designated areas nonattainment
for both the 1997 primary and secondary annual PM2.5 NAAQS
(which have identical levels of 15.0 [mu]g/m\3\). Designations for the
2012 primary annual PM2.5 NAAQS were made in January 2015
(80 FR 2206) and were effective on April 15, 2015. This action did not
make any changes to the designations that apply for the 1997 secondary
annual PM2.5 standard. Therefore, at this time, all areas
designated nonattainment in 2005 for the 1997 annual PM2.5
standard are considered as having been designated nonattainment for
both the 1997 primary annual PM2.5 NAAQS and for the 1997
secondary annual PM2.5 NAAQS. Similarly, for any 1997
PM2.5 nonattainment areas that have approved redesignation
requests for attainment of the 1997 PM2.5 NAAQS, the
redesignation applies to both the primary and secondary standards of
the 1997 PM2.5 NAAQS. A discussion of how transportation and
general conformity apply in this situation follows.
    CAA section 176(c)(5) requires compliance with transportation and
general conformity only in: (1) Nonattainment areas and (2) areas that
have been redesignated to attainment and are required to develop a
maintenance plan under CAA section 175A.
    CAA section 175A(a), in turn, establishes the requirements that
must be fulfilled by nonattainment areas in order to be redesignated to
attainment. That section only requires that nonattainment areas for the
primary standard submit a plan addressing maintenance of the primary
NAAQS in order to be redesignated to attainment; it does not require
nonattainment areas for secondary NAAQS to submit maintenance plans in
order to be redesignated to attainment. See 42 U.S.C. 7505a(a)
Therefore, since conformity does not apply in areas that have been
redesignated without CAA section 175A maintenance plans, the EPA
concludes that transportation and general conformity do not apply in
areas that have been redesignated to attainment for any secondary
NAAQS, such as the 1997 secondary annual PM2.5 NAAQS.
    Elsewhere in this final rule, the EPA is finalizing one of the
proposed options for revoking the 1997 primary annual PM2.5
NAAQS, which has been replaced by the more health protective 2012
primary annual PM2.5 NAAQS. As discussed in detail in
Section X of this preamble, the EPA is finalizing the option that calls
for revoking the 1997 primary annual PM2.5 NAAQS in areas
that have always been designated attainment for that NAAQS and in areas
that have been redesignated to attainment for that NAAQS. As a result,
after the effective date of the revocation, areas that have been
redesignated to attainment for the 1997 annual PM2.5 NAAQS
(i.e., maintenance areas for the 1997 annual PM2.5 NAAQS)
will not be

required to make transportation or general conformity determinations
for the 1997 annual PM2.5 NAAQS. The revocation would leave
nonattainment designations in place for the 1997 annual NAAQS for areas
that have not yet been redesignated to attainment for that NAAQS. The
EPA will continue to redesignate areas to attainment as states submit
redesignation requests for the remaining nonattainment areas. Any area
that is designated as nonattainment for the 1997 annual NAAQS at the
time of the initial revocation would have to continue to make
transportation and general conformity determinations for that NAAQS
until such time that they are redesignated to attainment for that
NAAQS.
    For any area that has been redesignated to attainment for the 1997
annual PM2.5 NAAQS (i.e., a maintenance area for the 1997
annual PM2.5 NAAQS) and is not designated nonattainment for
the 2012 primary annual PM2.5 NAAQS, the relevant planning
organization will not have to make conformity determinations for any
annual PM2.5 NAAQS after the effective date of the
revocation of the 1997 primary annual PM2.5 NAAQS because,
as discussed earlier, the CAA does not require maintenance areas for
secondary NAAQS to make conformity determinations and the 1997 primary
annual NAAQS will have been revoked. This means that, after the
effective date of the revocation, areas redesignated to attainment for
the 1997 annual PM2.5 NAAQS will no longer be required to
make metropolitan transportation plan, TIP, or project-level
transportation conformity determinations for that NAAQS. In addition,
federal agencies will no longer be required to make conformity
determinations for that NAAQS. Areas that remain designated
nonattainment for the 1997 annual PM2.5 NAAQS will continue
to make metropolitan transportation plan, TIP, and project-level
conformity determinations for that NAAQS and federal agencies will be
required to continue to make general conformity determinations for that
NAAQS in these areas until such time as these areas attain that NAAQS
and are redesignated to attainment (i.e., until the effective of the
redesignation to attainment). Table 3 shows which types of areas are
required to make conformity determinations for either the 1997 or 2012
annual PM2.5 NAAQS after the revocation of the 1997 primary
annual NAAQS is effective.

   Table 3--Where Is Conformity Required for the Various PM2.5 NAAQS After the Revocation of the 1997 Primary
                                               Annual PM2.5 NAAQS?
----------------------------------------------------------------------------------------------------------------
                                       1997 Primary and
          Attainment status            secondary annual     1997 24-Hour       2006 24-Hour       2012 Primary
                                            NAAQS              NAAQS              NAAQS           annual NAAQS
----------------------------------------------------------------------------------------------------------------
Nonattainment.......................                  X                  X                  X                  X
Redesignated to Attainment (i.e.,     .................                  X                  X                  X
 Maintenance).......................
----------------------------------------------------------------------------------------------------------------

    e. Impact of Implementation of a New or Revised PM2.5
NAAQS (such as the 2012 PM2.5 NAAQS) on a State's
Transportation and/or General Conformity SIP. As long as the EPA does
not make specific changes to its transportation or general conformity
regulations states should not need to revise their transportation and/
or general conformity SIPs. The EPA is not making any changes to its
transportation conformity regulations and no transportation conformity
SIP revisions are necessary. The only change that the EPA is making to
its general conformity regulations is to change the de minimis levels
in its general conformity regulations as discussed in Section IX.B.2.a
of this preamble. States with a general conformity SIP should evaluate
the need to revise those SIPs in light of this change. States with new
nonattainment areas may also need to revise conformity SIPs in order to
ensure the state regulations apply in any newly designated areas.
    In the event that a nonattainment designation causes transportation
conformity to apply for the first time in a state,\246\ such a state is
required by the statute and the EPA regulations to submit a SIP
revision that addresses three specific transportation conformity
requirements that address consultation procedures and written
commitments to control or mitigation measures associated with
conformity determinations for transportation plans, TIPs or projects.
(40 CFR 51.390) Additional information and guidance can be found in the
EPA's ``Guidance for Developing Transportation Conformity State
Implementation Plans'' (http://www3.epa.gov/otaq/stateresources/transconf/policy/420b09001.pdf).
---------------------------------------------------------------------------

    \246\ This is not currently the case for the areas designated
for the 2012 PM2.5 NAAQS, but the EPA is noting this in
the event that future designations result in this situation.
---------------------------------------------------------------------------

2. Additional General Conformity Requirements for PM2.5
Nonattainment Areas
    a. De minimis Emission Levels for Direct PM2.5 and its
Precursors. Federal actions estimated to have an annual net emissions
increase less than the de minimis levels established in the general
conformity regulations are not required to demonstrate conformity under
those regulations. For direct PM2.5 and its precursors
(SO2, NOX, VOC and ammonia), the existing de
minimis emission levels are set forth in the EPA's general conformity
regulations at 40 CFR 93.153(b)(1). Those levels were based on the
definition of a major stationary source for nonattainment NSR programs.
The EPA believes it is appropriate to continue this practice for
implementing the current and any future PM2.5 NAAQS.
However, because the definition of precursors currently in the general
conformity regulations at 40 CFR 93.153(b)(1) does not reflect the
rebuttable presumptions for certain PM2.5 precursors, the
EPA is finalizing changes to these conformity provisions to make them
consistent with the agency's revised precursor requirements.
Specifically, the current definition of precursors for PM2.5
in the general conformity regulations does not reflect the rebuttable
presumptions for VOC and ammonia. To address the lack of rebuttable
presumptions for VOC and ammonia the EPA is revising the tables in 40
CFR 93.153(b)(1) and (2) remove ``(if determined to be a significant
precursor)'' from the entries in the tables that apply to VOC and
ammonia emissions as PM2.5 precursors. It also does not
reflect the subpart 4 definitions for ``major source'' and ``major
stationary source'' that apply for Serious PM2.5
nonattainment areas. Therefore, the EPA is finalizing changes to the
PM2.5 precursor de minimis levels currently in 40 CFR
93.153(b)(1) to make those levels consistent with the statutory
requirements for major stationary source thresholds under subpart 4 and
any relevant changes finalized in Section III of this preamble.
Comments received on this proposed

change were supportive. The EPA is setting the de minimis levels that
apply to direct PM2.5 and PM2.5 precursors for
PM2.5 nonattainment areas for purposes of general conformity
as identified in Table 4.

    Table 4--General Conformity De Minimis Emission Levels for PM2.5
                               Precursors
------------------------------------------------------------------------
                                      Tons/year  in
                                      moderate PM2.5     Tons/year  in
                                      nonattainment      serious PM2.5
         Type of emission             areas and all      nonattainment
                                    maintenance areas        areas

------------------------------------------------------------------------
Direct emissions..................                100                 70
SO2...............................                100                 70
NOX...............................                100                 70
VOC...............................                100                 70
Ammonia...........................                100                 70
------------------------------------------------------------------------

    b. Implementation Considerations for the General Conformity
Program. The EPA did not propose any other revisions to the general
conformity regulations and is not taking any additional final actions
in this rule. However, as areas develop SIPs for the 2012 and future
PM2.5 NAAQS, the agency recommends that state and local air
quality agencies work with federal agencies with large facilities
(e.g., commercial airports, ports and large military bases) that are
subject to the general conformity regulations to establish an emissions
budget for those facilities in order to facilitate future conformity
determinations under the conformity regulations. Such a budget could be
used by federal agencies in determining conformity or identifying
mitigation measures if the budget level is included and identified in
the SIP.
    In a few cases, tracts of land under federal management may also be
included in nonattainment and maintenance area boundaries. The role of
fire in these areas should be assessed and emissions budgets developed
in concert with those federal land management agencies. In such areas
the EPA encourages states to consider in any baseline, modeling and SIP
attainment inventory used and/or submitted to include emissions
expected from projects subject to general conformity, including
emissions from wildland fire that may be reasonably expected in the
area. Where appropriate, states may consider developing plans for
addressing wildland fuels in collaboration with land managers and
owners. Information is available from DOI and USDA Forest Service on
the ecological role of fire and on smoke management programs and basic
smoke management practices.\247\
---------------------------------------------------------------------------

    \247\ USDA Forest Service and Natural Resources Conservation
Service, Basic Smoke Management Practices Tech Note, October 2011,
http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1046311.pdf.
---------------------------------------------------------------------------

C. Clean Data Policy

1. Summary of the Proposal
    In the proposed rule, the EPA described its longstanding clean data
policy and proposed to codify the policy in regulatory text. A clean
data determination (CDD) is a notice-and-comment rulemaking wherein the
EPA determines that a specific nonattainment area has attained the
relevant NAAQS based on 3 years of quality-assured certified air
quality monitoring data. The CDD suspends the state's obligation to
submit to the EPA the planning elements related to attaining the
standard required of nonattainment areas under the Clean Air Act for as
long as the area continues to attain the standard.\248\ The CDD does
not suspend certain CAA requirements, such as an emissions inventory,
nonattainment new source review requirements, and certain emission
reduction requirements, that are considered independent of attainment
needs.
---------------------------------------------------------------------------

    \248\ In the context of CDDs, the EPA distinguishes between
attainment planning requirements of the CAA, which relate to the
attainment demonstration for an area and related control measures
designed to bring an area into attainment for the given NAAQS as
expeditiously as practicable, and other types of requirements, such
as permitting requirements under the NNSR program, and any specific
control requirements independent of those strictly needed to ensure
timely attainment of the given NAAQS.
---------------------------------------------------------------------------

    The proposal provided additional discussion about attainment
demonstrations, control requirements for Moderate areas, RFP and
quantitative milestones, and contingency measures. With regard to
control requirements for Serious areas, the proposal included two
options: one option would suspend BACT/BACM requirements under a CDD if
elsewhere in the rule such requirements were considered necessary for
expeditious attainment, and the other option would not suspend BACT/
BACM requirements if elsewhere in the rule such requirements were
considered to be generally independent of attainment.
2. Final Rule
    The final rule codifies the clean data policy in rules governing
the implementation of current and future PM2.5 NAAQS, and
much of the guidance discussed in the proposal regarding which
requirements are suspended remains the same. The EPA has already
codified the clean data policy in a regulation implementing the 1997 8-
hour ozone NAAQS that was specifically challenged and upheld by the
D.C. Circuit in NRDC v. EPA, 571 F.3d 1245 (D.C. Cir. 2009), and
numerous United States Circuit Courts of Appeal have upheld the Clean
Data Policy, including the EPA's application of this interpretation of
the CAA with regard to implementation of the PM10 NAAQS
under subpart 4. See Latino Issues Forum v. EPA, Nos. 06-75831 and 08-
71238 (9th Cir. March 2, 2009) (memorandum opinion). The EPA had also
codified the clean data policy for PM2.5 in the now remanded
2007 PM2.5 implementation rule. For a complete discussion of
the Clean Data Policy's history and EPA's longstanding interpretation
under the Clean Air Act, please refer to the proposal.
    The planning elements under subpart 1 and subpart 4 generally
include reasonable further progress (RFP) requirements, attainment
demonstrations, RACM and RACT, nonattainment area contingency measures,
and other state planning requirements related to attaining the
NAAQS.\249\ The suspension of the

obligation to submit such requirements applies regardless of when the
plan submissions are due. The CDD does not suspend CAA requirements
that are independent of helping the area achieve attainment, such as
the requirements to submit an emissions inventory and nonattainment new
source review requirements. The determination of attainment is not
equivalent to a redesignation, and the state must still meet the
statutory requirements for redesignation in order to be redesignated to
attainment. A determination of attainment for purposes of the Clean
Data Policy/regulations is also not linked to any particular attainment
deadline, and is not necessarily equivalent to a determination that an
area has attained the standard by its applicable attainment deadline,
e.g., under CAA section 188(b). Note also that if the EPA determines
that an area with a clean data determination subsequently is violating
the standard prior to being redesignated to attainment, the area will
be required to address the pertinent requirements when it submits the
SIP to EPA. As has long been the EPA's policy, areas subject to a
determination that a CDD is rescinded due to subsequent violation of
the NAAQS would receive a reasonable amount of time to address the
previously suspended requirements and submit revisions to their SIPs.
The EPA would establish this SIP submittal date on a case-by-case
basis, taking into account individual circumstances surrounding the
particular SIP provisions at issue.\250\
---------------------------------------------------------------------------

    \249\ See December 14, 2004 memorandum from Stephen D. Page,
Director, EPA Office of Air Quality Planning and Standards, to Air
Division Directors, EPA Regions I-X, titled ``Clean Data Policy for
the Fine Particle National Ambient Air Quality Standards.''
Available at: http://www.epa.gov/airquality/urbanair/sipstatus/docs/pm25_clean_data_policy_14dec2004.pdf.
    \250\ Ibid.
---------------------------------------------------------------------------

    This rule specifies that a determination that a nonattainment area
is attaining the current and future PM2.5 NAAQS would
suspend the following attainment planning related requirements under
subpart 1 and subpart 4: (i) The part D, subpart 4 and subpart 1
obligation to provide an attainment demonstration pursuant to CAA
section 189(a)(1)(B); (ii) the RACM and RACT provisions of CAA section
189(a)(1)(C); (iii) the RFP and quantitative milestones provisions of
CAA section 189(c); and, (iv) related attainment demonstration, RACM
and RACT, RFP and contingency measure provisions requirements of
subpart 1, section 172. The following sections a-d provide additional
detail on the PM2.5 NAAQS planning requirements that would
be suspended by a CDD.
    a. Attainment Demonstrations. With respect to the attainment
demonstration requirements of section 172(c) and section 189(a)(1)(B)
of the CAA, the EPA finds that if an area already has air quality
monitoring data demonstrating attainment of the standard, there is no
need for an area to make a further submission containing additional
measures to achieve attainment, nor is there a need for the area to
perform future modeling to show how the area will achieve attainment.
The plain language of CAA section 189(a)(1)(B) requires that the
attainment plan provide for ``a demonstration (including air quality
modeling) that the [SIP] will provide for attainment by the applicable
attainment date.'' Where the area has attained the standard, such a
demonstration no longer serves a purpose.
    b. Control Measure Requirements for Moderate Areas. Both CAA
sections 172(c)(1) and 189(a)(1)(C) require ``provisions to assure that
reasonably available control measures'' (i.e., RACM) are implemented in
a nonattainment area. Reasonably available control technology (i.e.,
RACT) is a subset of RACM. The EPA has long interpreted ``reasonably
available control measures'' under CAA sections 172(c)(1) and
189(a)(1)(C) to mean only those measures that are necessary to help an
area achieve attainment. Thus, where an area is already attaining the
standard, no additional RACM are required, but all measures adopted
into the SIP prior to attainment would remain. The EPA is interpreting
CAA section 189(a)(1)(C) consistent with its interpretation of CAA
section 172(c)(1).
    c. RFP and Quantitative Milestones. The EPA has long interpreted
the provisions of part D, subpart 1 of the CAA (sections 171 and 172)
as not requiring the submission of RFP for an area already attaining
the PM10 NAAQS. For an area that is attaining, showing that
the state will make RFP towards attainment ``will, therefore, have no
meaning at that point.''
    d. Contingency Measures. Other SIP submission requirements are
linked with these attainment demonstration and RFP requirements, and
similar reasoning applies to them. These requirements include the
contingency measure requirements of CAA sections 172(c)(9). The EPA has
interpreted the obligation to submit contingency measure requirements
of CAA sections 172(c)(9) as suspended when an area has attained the
standard because those ``contingency measures are directed at ensuring
RFP and attainment by the applicable date.'' 57 FR at 13564; see also
Seitz memo at pgs. 5-6.
    e. Control Measure Requirements for Serious Areas. Section VII.D of
the preamble explains the rationale of the EPA's decision to maintain
its longstanding policy of considering the BACT/BACM requirement of CAA
section 189(b)(1)(B) to be generally independent of attainment.
Accordingly, this rule states that a clean data determination would not
suspend the obligation for the state to submit any applicable
outstanding BACM and BACT requirements.
    For a Serious area that failed to attain the relevant
PM2.5 NAAQS by the applicable attainment date and that is
therefore subject to the annual 5 percent emissions reduction
requirement under CAA section 189(d), but is nevertheless now attaining
the relevant NAAQS, the EPA believes that the Clean Data Policy may
apply to the obligations of the state to make an attainment plan
submission to meet the requirements of CAA section 189(d). Once such an
area is attaining the relevant NAAQS, a clean data determination would
suspend the CAA section 189(d) submission requirement.
3. Comments and Responses
    Comment: Several commenters supported the EPA's proposal to codify
the clean data policy in the final rule because they believe the policy
is lawful and relieves states from unnecessary planning burdens in
areas where the NAAQS is met. Some commenters stated the policy has
specifically been upheld by the D.C. Circuit in the context of review
of nationally applicable implementation rules for the EPA's ozone NAAQS
[Natural Res. Def. Council v. EPA, 571 F.3d 1245, 1260-61 (D.C. Cir.
2009)]. Other commenters, however, asserted that they ``reiterate their
previous comments regarding the illegality of the Clean Data Policy.''
To the extent that the Agency planned to continue to follow the policy,
these commenters agreed with the EPA's interpretation that only those
requirements tied to an area's demonstration of attainment should be
suspended. To that end, the commenters requested clarification that
measures that have been responsible for the area's attainment must be
submitted and approved into the SIP even following a Clean Data
Determination. Similarly, other commenters requested clarification as
to EPA's statement that ``Thus, where an area is already attaining the
standard, no additional RACM are required, but all measures adopted
into the SIP prior to attainment would remain.'' The commenter wondered
if ``all measures adopted into the SIP'' includes measures that were
included and identified as RACT or RACM in the original SIP, even if
those measures have not yet been submitted to EPA in regulatory form.
    Finally, some commenters noted that the Act requires that RACM/RACT
be

implemented within 4 years of a nonattainment designation and stated
that, as sources reduce emissions of PM2.5 and regional PM
precursors due to national rules yet to be fully implemented (e.g.,
Boiler NESHAPS, CSAPR) it is entirely possible that an area may attain
the standard prior to complete implementation of RACM/RACT. The
commenters stated that, if an area attains the NAAQS prior to
implementation of the planning requirements, it is meaningless and
overly burdensome to require the area to continue implementing RACM/
RACT.
    Response: The EPA disagrees with commenters who allege, without
explanation, that the Clean Data Policy is ``illegal.'' Rather, as
noted by supportive commenters, the EPA has long interpreted certain
CAA requirements that are designed to bring an area into attainment to
serve no purpose once an area is attaining, and thus has interpreted
the Act as permitting the Agency to suspend the requirements to submit
revisions to the SIP addressing those requirements. This position has
been upheld by multiple Circuit Courts of Appeals.\251\
---------------------------------------------------------------------------

    \251\ See, e.g., NRDC v. EPA, 571 F.3d 1245 (D.C. Cir. 2009);
Sierra Club v. EPA, 99 F.3d 1551 (10th Cir. 1996); Latino Issues
Forum v. EPA, Nos. 06-75831 and 08-71238 (9th Cir. March 2, 2009)
(memorandum opinion).
---------------------------------------------------------------------------

    In response to the requests for clarification of which RACM
requirements are suspended by a CDD, we note that, for over 30 years,
the EPA has consistently interpreted the RACM requirement in CAA
section 172(c)(1) to apply only to those measures that, individually or
collectively, contribute to expeditious attainment of the NAAQS. The
suspension of the statutory requirement to submit RACM is premised on
the idea that, ``[t]o the extent an area is already achieving
attainment as expeditiously as possible, imposition of additional
control [measures] would not hasten achievement of the NAAQS. In such a
situation, the EPA may reasonably conclude that no control [measures]
are reasonably available and the area need not implement further
[measures] to satisfy the [RACM] requirement.'' See NRDC v. EPA, 571
F.3d 1245, 1253 (D.C. Cir. 2009). Thus, upon the EPA's finalization of
a CDD for a particular NAAQS, the EPA formally suspends the obligation
to submit attainment-related plan elements for that particular NAAQS,
including RACM. A CDD does not, however, affect the criteria in CAA
section 107(d)(3)(E) for redesignation to attainment, including the
requirement for the state to demonstrate to the EPA's satisfaction that
the improvement in air quality is due to ``permanent and enforceable
reductions in emissions resulting from implementation of the applicable
implementation plan'' and other permanent and enforceable reductions.
Thus, to the extent certain state/local control measures were necessary
to an area's attainment of the NAAQS, the state may need to submit
those measures to the EPA for SIP approval in order to meet the
statutory criteria for redesignation in CAA section 107(d)(3)I,
notwithstanding the suspension of planning obligations under a CDD.
    In this case, it is not clear to the EPA what the commenter means
by the phrase ``original SIP,'' since the SIP is only those measures
that have been submitted and approved by the EPA. To the extent that a
measure was adopted into the SIP prior to an area's attainment of the
NAAQS, and therefore contributed to an area's attainment, that measure
is therefore required to remain as part of the SIP. We infer that the
comment might be referring to commitments that were approved into a SIP
to adopt future measures, or that commenters might be asking for
clarification regarding measures that have been adopted locally or at a
state level prior to the area's coming into attainment but have not yet
been submitted to the EPA for approval into the federally-approved SIP.
As explained above, a CDD has no effect on the state's obligation to
demonstrate that an area's improvement in air quality is due to
``permanent and enforceable'' emissions reductions in order to meet the
statutory requirements for redesignation to attainment in CAA section
107(d)(3)(E). Additionally, a CDD does not alter the effect of any
measure (including any state commitment) that has already been approved
into a SIP, even if that measure is a commitment to adopt or submit a
future measure. Once approved into a SIP, such a measure becomes an
enforceable emission standard or limitation subject to EPA or citizen
enforcement under CAA section 304, which cannot be altered except
through a SIP revision approved by the EPA. Along those same lines,
even if an area has adopted into its SIP RACM/RACT but has yet to fully
implement those measures when the area first starts attaining the
NAAQS, a CDD does not excuse the area from continuing to implement its
SIP requirements, i.e., the RACM/RACT measures that have been approved
into the SIP. The CDD merely suspends the requirement to submit RACM/
RACT, that is, additional measures on top of what brought the area into
attainment; a state may only stop implementing those measures already
in its SIP through a SIP revision approved by the EPA.
    Comment: Some commenters supported the EPA's proposal to retain the
BACM/BACT submission requirement even with a CDD (80 FR 15444). Other
commenters, however, stated that, once the EPA makes an attainment
determination, the EPA should suspend the requirements to submit BACM/
BACT and that to do otherwise is illogical.
    Response: The EPA is finalizing the option that requires BACM/BACT
to be submitted even if the EPA has issued a CDD for an area. As
discussed in our proposal and earlier in this section, the legal
underpinning of the Clean Data Policy is that the EPA interprets the
CAA not to require the submission of requirements that are designed to
get an area to attainment once that area is already attaining the
NAAQS. Thus, only those ``attainment planning'' requirements are
suspended by a CDD. It is therefore illogical for the EPA to extend the
Clean Data Policy to the submission of the BACM/BACT requirement for
Serious Areas. Because the EPA interprets BACM/BACT as independent of
attainment, as discussed above in Section VII.D of the preamble, the
requirement to submit BACM/BACT continues to apply regardless of
whether the EPA has determined that the area is attaining.

D. CAA Section 179B/International Border Areas

1. Specific Requirements
    a. Summary of Proposal. Section 179B of the CAA, titled
``International Border Areas,'' applies to areas that would attain the
relevant NAAQS by the statutory attainment date ``but for'' emissions
emanating from outside the U.S. Under CAA section 179B, if applicable,
the provision modifies subpart 4 attainment plan obligations applicable
to areas designated nonattainment for any PM NAAQS. The EPA proposed
and sought comment on two approaches that would give greater clarity to
the agency's existing interpretation of the RACM/RACT and additional
reasonable measure requirements for Moderate area attainment plans to
be approved under CAA section 179B. The first proposed interpretation
would have clarified that the control strategy for an area that could
attain by the Moderate area attainment date, ``but for'' foreign
emissions of direct PM2.5 or its precursors, must include
all control measures identified by the state to be

technologically and economically feasible and implementable on sources
in the area by the end of the sixth calendar year following designation
of the area. Under this approach, inclusion of such measures would
satisfy requirements for RACM and RACT (for measures that can be
implemented within four years) and additional reasonable measures (for
measures than can be implemented within six years but not within four).
The proposal also sought comment on a possible exception for any such
measures that collectively would not be effective in reducing ambient
PM2.5 levels in the area. The second proposed approach would
have required a state to demonstrate that its selected control measures
for a Moderate nonattainment area would achieve reductions in
PM2.5 levels that exceeded the applicable NAAQS in
proportion to their contribution to overall PM2.5 levels.
Inclusion of these proportional measures would thus satisfy RACM/RACT
and additional reasonable measures under the second approach. The EPA
sought comment on these two approaches to clarify what constitutes a
reasonable control strategy in the context of a SIP submitted pursuant
to CAA section 179B.
    The EPA also proposed that any Moderate area attainment plan
submitted under CAA section 179B must include an RFP plan with required
air quality targets consistent with the RFP Option 2. In addition, the
EPA proposed requirements for establishing and reporting on
quantitative milestones for areas with approved ``but for''
demonstrations.
b. Final Rule
    Section 179B(a) of the CAA provides that the EPA shall approve an
attainment plan for a nonattainment area that is an international
border area if: (i) the attainment plan meets all other applicable
requirements of the CAA, and (ii) the submitting state can demonstrate
satisfactorily that ``but for emissions emanating from outside of the
United States,'' the area would attain and maintain the relevant NAAQS.
In addition, CAA section 179B(d) provides that if a state demonstrates
that an area would have attained the NAAQS but for emissions emanating
from outside the U.S., then the area is not subject to the mandatory
reclassification element of CAA section 188(b)(2) for Moderate areas
that fail to attain by the applicable attainment date.
    Under CAA section 179B, areas affected by emissions from outside
the U.S. continue to have attainment plan obligations. First, even if
the area is impacted by emissions from outside the U.S., that fact does
not affect the designation of the area. Such an area that is violating
the relevant NAAQS will be designated nonattainment even if emissions
from outside the U.S. contribute to that violation. Second, as a result
of that designation, the state is required to meet the applicable
attainment plan requirements for the relevant NAAQS. Section 179B of
the CAA does not negate the attainment plan requirements. Rather, it
allows the EPA to approve an attainment plan that demonstrates
attainment and maintenance of the NAAQS ``but for'' international
emissions.
    The EPA has determined that under the best reading of CAA section
179B, states remain obligated to meet the attainment plan requirements
other than the requirement to demonstrate attainment and maintenance of
the relevant NAAQS. This determination is based upon the fact that
179B(a)(1) explicitly states that such an attainment plan must meet all
the requirements of the CAA with that exception. The applicable
requirements for an attainment plan for PM2.5 include those
requirements that apply to a Moderate area attainment plan. Those
requirements include an emissions inventory, RACM and RACT, additional
reasonable measures, RFP, quantitative milestones, contingency
measures, NNSR and motor vehicle emissions budgets for transportation
conformity purposes. The Addendum includes a discussion of the
applicable attainment plan requirements in the context of developing a
SIP subject to CAA section 179B. In it, the EPA clarified that ``RACM/
RACT must be implemented to the extent necessary to demonstrate
attainment by the applicable attainment date if emissions emanating
from outside the U.S. were not included in the analysis.'' \252\ The
EPA further encouraged states ``to reduce emissions beyond the minimum
necessary to satisfy the `but for' test in order to reduce the PM
concentrations to which their populations are exposed.'' \253\ However,
the EPA acknowledged that ``if . . . States . . . were also required,
because of contributions to PM10 violations caused by
foreign emissions, to shoulder more of a regulatory and economic burden
than States not similarly affected. . .such a requirement would
unfairly penalize States containing international border areas and
effectively undermine the purpose of CAA section 179B. Indeed, to the
extent an affected State can satisfactorily demonstrate that
implementation of such measures clearly would not have advanced the
attainment date, the EPA could conclude they are unreasonable and hence
do not constitute RACM.'' \254\
---------------------------------------------------------------------------

    \252\ Addendum to the General Preamble, 59 FR 41998 (August 16,
1994), at page 42001.
    \253\ Ibid.
    \254\ Ibid.
---------------------------------------------------------------------------

    In the proposal, the EPA specifically took comment on the most
appropriate way to address the RACM and RACT requirements. The past
interpretation of RACM and RACT requirements in the context of CAA
section 179B was considered when the agency proposed an option to allow
a state not to adopt such measures if the state could demonstrate that
collectively the measures will not be effective in reducing
PM2.5 levels in the area. Some commenters supported this
exception, stating that it would prevent wasting resources on
ineffective measures. Some commenters stated that requiring
implementation of all RACM/RACT and additional reasonable measures
circumvents Congressional intent and the CAA. Other commenters
disagreed, stating that these areas should implement all measures due
to the importance to public health.
    Regarding RACM/RACT and additional reasonable measures, the EPA
reviewed the comments received and its past interpretation of RACM and
RACT requirements in the context of CAA section 179B attainment plans
for PM2.5 NAAQS. The EPA is persuaded that this approach is
most appropriate and most consistent with the Act and with the control
requirements for other Moderate areas that demonstrate they cannot
practicably attain by the Moderate area attainment date. See section
51.1009(a)(4)(ii). In longstanding guidance the EPA has encouraged
states ``to reduce emissions beyond the minimum necessary to satisfy
the `but for' test in order to reduce the PM10
concentrations to which their populations are exposed.'' \255\ Given
that the primary purpose of an attainment plan is to ensure expeditious
attainment of the NAAQS and protection of public health and welfare
through implementation of control measures that achieve emissions
reductions, adopting an interpretation that would allow for continued
emissions of pollutants that the state could reasonably reduce would be
antithetical to the objectives of the CAA. Just as it is appropriate
and consistent with the Act to adopt reasonable measures (i.e., RACT/
RACM or additional reasonable measures) in areas that cannot
practicably attain by the attainment date, as previously discussed, it
is also appropriate and

consistent with the Act to adopt reasonable measures in areas that
cannot attain due to international emissions.
---------------------------------------------------------------------------

    \255\ Ibid.
---------------------------------------------------------------------------

    Therefore, the EPA requires that Moderate area attainment plans
approved under CAA section 179B must implement all technologically and
economically feasible measures that can be implemented on sources in
the area by the end of the sixth calendar year following designation of
the area (i.e., RACM and RACT and additional reasonable measures). This
requirement is intended to ensure that the area makes reasonable
progress toward attaining the standard even if such measures are not
expected to yield attainment by the statutory Moderate area attainment
date. This approach parallels the requirements described in Section
IV.D in this preamble, pursuant to CAA section 189(a)(1), for Moderate
PM2.5 nonattainment areas that cannot practicably attain the
NAAQS by the latest statutory attainment date for the area. Requiring
the implementation of all reasonable measures is even more important in
the context of a Moderate area for which CAA section 179B applies
because sources in such areas will not be subject to the more stringent
BACM/BACT, MSM, or 5 percent requirement because such areas are not
subject to mandatory reclassification as Serious areas pursuant to CAA
section 179B(d). Thus, the only level of PM2.5 control
requirements that will likely ever apply to these sources is the less-
stringent RACM/RACT and additional reasonable measures level of
control; therefore, all the sources in the area should reduce emissions
if such reduction is reasonable since the public in those areas will
continue to be subject to ambient levels of emissions that the agency
has determined are unsafe notwithstanding implementation of those
reasonable measures. Additionally, the EPA notes that the process to
determine RACM already allows states to identify the subset of all
control measures that are technologically and economically feasible,
which should be adequate to prevent significant wasting of resources on
ineffective measures.
    The EPA has determined that it will not finalize the proposed
option of achieving reductions in PM2.5 levels in proportion
to the area's contribution to overall PM2.5 levels. The EPA
received several comments on the proposed option to allow states to
implement control measures for a Moderate nonattainment area with a
plan approved under CAA section 179B that would achieve reductions in
PM2.5 levels in proportion to the area's contribution to
overall PM2.5 levels. Although some commenters supported the
possibility of proportionally implementing control measures, other
commenters raised possible negative consequences of this option.
Commenters highlighted the difficulty that states would face in
apportioning responsibility for emissions between foreign and non-
foreign sources, which would be necessary under the proportional
approach. These commenters also disagreed as to whether the EPA or
states should be responsible to determine the proportional allocation
of international emissions. The EPA is also concerned that a
proportional approach would introduce too much complexity into an
already complex analytical process. Additionally, the EPA notes that no
other NAAQS pollutant offers a proportional approach to implementation
of control measures and is not convinced that there are sufficient
reasons to finalize this approach for PM2.5 nonattainment
areas.
    Section 179B(d) of the CAA states that any area for which the state
establishes to the EPA's satisfaction that the area ``would have
attained the NAAQS by the applicable attainment date, but for emissions
emanating from outside the United States, shall not be subject to the
provisions of section [188(b)(2)].'' CAA section 188(b)(2) requires the
EPA to determine, within 6 months following the applicable attainment
date for a Moderate PM2.5 nonattainment area, whether the
area attained the NAAQS by that date and to reclassify the area as
Serious if it is not in attainment after the applicable attainment
date. For any Serious area subject to an EPA determination of failure
to attain by the Serious area attainment date, CAA section 189(d)
requires the state to submit plan revisions which provide for
attainment of the PM2.5 NAAQS and for annual emissions
reductions of not less than 5 percent until the area attains. These
planning requirements in section 189(d) apply only upon the EPA's
determination that a Serious area has failed to attain the applicable
NAAQS by the Serious area attainment date. Because section 179B(d)
explicitly provides that any area that satisfies the ``but for''
attainment test in CAA section 179B shall not be subject to the
provisions for reclassification to Serious upon failure to attain in
CAA section 188(b)(2), the consequences for failure to attain by the
Serious area attainment date in section 189(d) generally do not apply
to such areas.
    In the event that the EPA has already reclassified an international
border area as Serious, when the state submits a ``but for''
demonstration under section 179B, all of the Serious area requirements
that apply to the area (e.g., the requirements to implement BACM/BACT
and additional feasible measures) would remain in effect. This is
because at the time the state submits the ``but for'' demonstration,
these statutory requirements already apply. Upon the EPA's approval of
a Serious area plan and section 179B demonstration for such an area,
however, the EPA would no longer be obligated to make a determination
of failure to attain by the Serious area attainment date triggering the
additional planning requirements of section 189(d). Consistent with
Congress's clear intent in section 179B(d) to relieve Moderate
PM2.5 nonattainment areas that satisfy the ``but for''
attainment test of the additional planning obligations that result from
a mandatory determination of failure to attain by the Moderate area
attainment date, the EPA interprets section 179B as also relieving
Serious PM2.5 nonattainment areas of the additional planning
obligations in section 189(d) that result from a mandatory
determination of failure to attain by the Serious area attainment date,
once the EPA approves the state's Serious area plan and section 179B
demonstration.
    Where a Serious area fails to attain by the Serious area attainment
date and is therefore subject to the requirements of section 189(d),
the EPA's approval of a section 189(d) plan and 179B demonstration
would mean that the EPA is no longer obligated to make further
determinations of failure to attain or to trigger additional planning
requirements. The EPA intends to review each SIP submission containing
a ``but for'' attainment demonstration for an international border area
for compliance with the requirements of section 179B.
    The EPA notes that, with one exception for contingency measures,
the final rule provisions governing for the RFP, quantitative
milestone, and contingency measure requirements for PM2.5
nonattainment areas are the same for areas seeking plan approval under
CAA section 179B as they are for any other area. For example, the EPA
requires that as part of any Moderate area attainment plan submitted
under CAA section 179B, a state must include an RFP plan developed
consistent with the process described in Section IV.F of this preamble
as a Moderate nonattainment area that cannot practicably attain the
relevant NAAQS by the statutory attainment date. In addition, the EPA
requires that the state must identify quantitative milestones for the
area to be achieved 4.5 years and

7.5 years from the date of designation of the area. The EPA will apply
the same requirements for establishing and reporting on quantitative
milestones for Moderate nonattainment areas with an approved ``but
for'' demonstration under CAA section 179B as for all other Moderate
nonattainment areas, as described in Section IV.G of this preamble.
Furthermore, the state must include as part of any attainment plan
submission made for such an area contingency measures that are ready to
be implemented quickly and with minimal further action by the state or
by the EPA in the event the EPA determines that such area failed to
meet RFP or quantitative milestone requirements. The contingency
measures should achieve approximately 1 year's worth of emissions
reductions as calculated by the state for purposes of the RFP analysis.
The exception to the contingency measure requirement for areas with
approved CAA section 179B demonstrations is that contingency measures
for failure to attain are not required in such plans, because under CAA
section 179B(d) the EPA is not required to make determinations
concerning attainment for such areas. Further explanation of
contingency measures can be found in Section IV.H of this preamble.
    Regarding the ``but for'' demonstrations under CAA section 179B,
the EPA has historically evaluated these demonstrations on a case-by-
case basis, based on the individual circumstances and data provided by
the submitting state. These demonstrations have included information
such as ambient air quality monitoring data, modeling scenarios,
emissions inventory data and meteorological or satellite data.\256\ The
Moderate area attainment demonstration modeling and other elements of
the attainment demonstration must show attainment and maintenance of
the NAAQS but for the emissions from outside of the U.S. However, CAA
section 179B does not provide authority to exclude monitoring data
influenced by international transport from regulatory determinations
related to attainment and nonattainment.
---------------------------------------------------------------------------

    \256\ Ibid. The Addendum includes further examples of
information a state may present for the EPA to consider as part of
the ``but for'' demonstration, including additional monitors in
international border areas, more detailed emissions inventories, and
speciation data that identifies PM2.5 components from
foreign sources.
---------------------------------------------------------------------------

    Where international transport of emissions contributes to an
exceedance or violation, such data may be excluded from consideration
only if they were significantly influenced by exceptional events under
section 319(b) of the CAA. If the data meet the criteria contained in
the EPA's Exceptional Events Rule, the exceedance can be addressed by
that rule.\257\ Specifically, if the EPA concurs with a state's request
to exclude affected data, the event-influenced data are officially
noted and removed from the data set used to calculate official design
values, which may be used as part of a regulatory determination.
---------------------------------------------------------------------------

    \257\ See 40 CFR 40 CFR 50.1, 50.14 and 51.930.
---------------------------------------------------------------------------

    The EPA expects that the best approach for evaluating the potential
impacts of international transport on nonattainment is for states to
work with the EPA on a case-by-case basis to determine the most
appropriate information and analytical methods for each area's unique
situation. The EPA will work with states that are developing
exceptional events demonstrations and attainment plans for which CAA
section 179B is relevant, and ensure the states have the benefit of the
EPA's understanding of international transport of PM2.5 and
PM2.5 precursors.
c. Comments and Responses
    Comment: Commenters stated the EPA should not require the state to
implement a section 189(d) 5 percent reduction plan, since attaining
such reductions may well be impossible if there are significant
international emissions.
    Response: The EPA agrees that as long as the affected nonattainment
area satisfactorily meets the provisions of CAA section 179B, that area
should not be subjected to the additional requirements of CAA section
189(d) even if the area fails to attain.
    Comment: Commenters stated that requiring implementation of all
RACM and RACT for CAA section l79B nonattainment areas would penalize
rural communities and would run counter to the intent of CAA section
179B of providing regulatory relief to areas affected by foreign
emissions.
    Response: For the reasons stated earlier, the EPA has determined
that section 179B nonattainment areas should be required to implement
control measures to the same extent as a Moderate nonattainment area
that demonstrates it will not be able to attain the PM2.5
NAAQS by the statutory attainment date.
    Comment: Some commenters stated that the EPA's current
interpretation of section 179B and the agency's guidance which
encourages states ``to reduce emissions beyond the minimum necessary to
satisfy the `but for' test,'' circumvents Congressional intent and the
CAA and establishes a second ambient air quality threshold not related
to the NAAQS.
    Response: The EPA disagrees that encouraging states to minimize
emissions as much as possible to protect public health circumvents
Congressional intent. The EPA has determined that the reasonable
control measure requirements outlined in section 51.1009(a)(4)(ii)
represent the most appropriate interpretation of the CAA in line with
the overriding Congressional intent to protect and improve air quality
thereby enabling the associated public health benefit.
    Comment: Some commenters stated that if an area's demonstration is
approved under CAA section 179B, any contingency measures should only
be required to obtain emissions reductions in proportion to the
contribution of emissions excluding the international pollution, or at
least to the contribution of emissions reductions that the state can
feasibly attain.
    Response: The EPA agrees that contingency measures relate to the
domestic portion of emissions affecting the nonattainment area. The
state will not be required to develop contingency measures to make up
for those emissions coming from international sources. The EPA
emphasizes that contingency measures for a section 179B area will be
for failure to meet RFP requirements, not for failure to attain.
    However, the EPA expects states with a section 179B area to follow
the guidance and requirements outlined in Section IV.H of this preamble
to identify contingency measures that can provide emissions reductions
from sources within the state's jurisdiction. As discussed in Section
IV.H of the preamble, this should include an explanation of the amount
of anticipated emissions reductions to be accomplished by the
contingency measures. If such an area is unable to identify
approximately 1 year's worth of emissions reductions to constitute
contingency measures, the explanation should describe the factors
considered by the state when reaching this conclusion.

E. Enforcement and Compliance

    a. Summary of Proposal. The agency proposed that in general, in
order for a SIP regulation to be enforceable, it must clearly spell out
which sources or source types are subject to its requirements and what
its requirements (e.g., emission limits or work practices) are. The EPA
proposed that an enforceable regulation would also specify the
timeframes within which these requirements must be met, and

definitively state the recordkeeping and monitoring requirements
appropriate to the type of sources being regulated. Additionally, the
EPA proposed that an enforceable regulation would also contain test
procedures in order to determine whether sources are in compliance.
    b. Final Rule. Section 172(c)(6) in subpart 1 of the CAA requires
nonattainment SIPs to ``include enforceable emission limitations, and
such other control measures, means or techniques . . . as well as
schedules and timetables for compliance, as may be necessary or
appropriate to provide for attainment.'' In the remanded 2007
PM2.5 Implementation Rule, the EPA described the general
elements that characterize an enforceable SIP regulation, recognizing
that enforceable SIP regulations may address the elements in different
ways depending on the type of source category being regulated. The
agency continues to believe and hereby finalizes that in general, in
order for a SIP regulation to be enforceable, it must clearly spell out
which sources or source types are subject to its requirements and what
its requirements (e.g., emission limits or work practices) are. An
enforceable regulation would also specify the timeframes within which
these requirements must be met, and definitively state the
recordkeeping and monitoring requirements appropriate to the type of
sources being regulated. The recordkeeping and monitoring requirements
would have to be sufficient to enable the state or the EPA to determine
whether the source is complying with the emission limit on a continuous
basis. An enforceable regulation would also contain test procedures in
order to determine whether sources are in compliance.
    The EPA continues to believe that complete and effective
regulations that ensure compliance with an applicable emissions limit
must include requirements for both performance testing of emissions and
ongoing monitoring of the compliance performance of control measures,
and the agency requires that SIP regulations that establish emission
limits include the following for performance testing:
    (1) Indicator(s) of compliance--the pollutant or pollutants of
interest (e.g., filterable and condensable PM2.5) and the
applicable units of measurement for expressing compliance (e.g., ng/J
of heat input, lb/hr);
    (2) Test method--reference to a specific EPA or other published set
of sample collection and analytical procedures, equipment design and
performance criteria, and the calculations providing data in units of
the indicator of compliance (Section IX.K of this preamble presents a
discussion of specific test methods for condensable PM2.5
emissions);
    (3) Sample collection characteristics--conditions related to the
sample collection portion of the performance test. Such conditions
would include duration of sampling period, either on a time or volume
collected basis; the number of runs comprising a test (e.g., three runs
per test); and the averaging period, i.e., the time over which the
emissions limit is averaged (e.g., 8 hours); and,
    (4) Frequency--the time between emissions or performance tests
(e.g., within 30 days of facility start-up and once each successive
quarter, every 6-month period, or yearly).
    In order to be complete with regard to compliance monitoring
provisions, the EPA requires that regulations adopted into the SIP must
include the following critical elements:
    (1) Indicator(s) of performance--the parameter or parameters
measured or observed for demonstrating proper operation of the
pollution control measure or compliance with the applicable emissions
limitation or standard. Indicators of performance could include direct
or predicted emissions measurements, process or control device (and
capture system) operational parametric values that correspond to
compliance with efficiency or emissions limits, and recorded findings
of verification of work practice activities, raw material or fuel
pollutant content, or design characteristics. Indicators could be
expressed as a single maximum or minimum value, a function of process
variables (e.g., within a range of pressure drops), a particular
operational or work practice status (e.g., a damper position,
completion of a waste recovery task), raw material or fuel pollutant
content, or an interdependency between two or more variables;
    (2) Measurement technique--the means used to gather and record
information of or about the indicators of performance. The components
of the measurement technique include the detector type or analytical
method, location and installation specifications, inspection
procedures, and quality assurance and quality control measures.
Examples of measurement approaches include continuous emissions
monitoring systems (CEMS), continuous opacity monitoring systems
(COMS), continuous parametric monitoring systems (CPMS), performance
testing, vendor or laboratory analytical data, and manual inspections
and data collection that include making records of process conditions,
raw materials or fuel specifications, or work practices. Directly
enforceable emission measurements, such as PM CEMS, are preferred
wherever feasible. Where COMS are feasible, it should be clear that
opacity is a directly enforceable standard, not merely an indicator of
compliance;
    (3) Averaging time--the period over which to average data to verify
compliance with the emissions limitation or standard or proper
operation of the pollution control measure. Examples of averaging time
include a 3-hour average in units of the emissions limitation, a 30-day
rolling average emissions value, a daily average of a control device
operational parametric range, periodic (e.g., monthly, annual) average
of raw materials or fuel pollutant content, and an instantaneous alarm;
    (4) Monitoring frequency--the number of monitoring data values
recorded over a specified time interval. Examples of monitoring
frequencies include at least one data value every 15 minutes for CEMS
or CPMS, at least every 10 seconds for COMS, upon receipt or
application of raw materials or fuel to the process, or at least once
per operating day (or week, month, etc.) for performance testing, work
practice verification, or equipment design inspections; and,
    (5) Reporting and record retention requirements--criteria for
retaining monitoring and test data in an electronic form and periodic
electronic reporting of information as needed to the compliance office.
Electronic record retention and submission have been widely adopted,
and the EPA believes that such readily accessible documentation could
be used by state, federal and other analysts to spot trends and non-
compliance more easily than if these entities conducted reviews of
paper documents. The EPA also recommends that compliance reports be
made available online so that the general public can readily access the
information without the need to submit Freedom of Information Act
(FOIA) requests to the EPA. The EPA is in the process of revising
federal rules to make similar requirements apply.
    The EPA acknowledges that one way for regulatory authorities to
have owners or operators of regulated sources demonstrate compliance
via ongoing monitoring is to use a Compliance Assurance Monitoring
(CAM) rule-type approach.\258\ Under such an approach,

an owner or operator would be able to establish operating ranges of
continuously monitored parameters determined through concurrent
performance testing as indicators of performance. A CAM rule-type
approach would require owners or operators who chose parameter
monitoring as indicative of compliance to immediately take corrective
action should a measured parameter value occur outside the demonstrated
range associated with compliance. Moreover, concurrent performance
testing and parameter measurement would be necessary on a periodic
basis, generally annually, and may be necessary on a more frequent
basis to reverify or reset parameter value range, particularly when the
operating range is exceeded. Failure of the owner or operator to take
immediate corrective action would constitute a violation of the
applicable rule. Moreover, failure of a parameter range to demonstrate
compliance when reverification or resetting performance testing
occurred would also constitute a violation of the emission limit. This
implementation rule does not prohibit states from taking a CAM rule
type approach and making parameters directly enforceable limits.
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    \258\ See the CAM rule, available at 40 CFR part 64.
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    The EPA continues to believe that approval of regulations adopted
into SIPs should ensure that these critical elements are present and
clearly defined to be approvable. In particular, the compliance
obligations, including emissions limits and other applicable
requirements, should be representative of and accountable to the
assumptions used in a state's attainment demonstration. This
accountability should include the ability to transfer the applicable
regulatory requirements to a title V operating permit subject to the
EPA and public review.\259\
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    \259\ Under the title V regulations, sources have an obligation
to include in their title V permit applications, among other
components, all emissions of pollutants for which the source is
major, and all emissions of regulated air pollutants. See, e.g., 40
CFR 70.5(c)(3). The definition of regulated air pollutant in 40 CFR
70.2 includes any pollutant for which the NAAQS has been
promulgated, including PM2.5.
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c. Comments and Responses
    Comment: Commenters suggested that the proposal's use of the term
``indicators of compliance'' is confusing and suggested the EPA should
simply express that emission limitations must identify the pollutant of
interest and the units of measurement. The commenters suggested the EPA
use the term ``measurement method'' and the EPA acknowledge that
sources may use procedures that are not published by the EPA,
especially for pollutants for which there is no federally promulgated
test method, performance specification, or voluntary consensus
standard. The commenters disagreed that ``averaging time'' is always
the appropriate term, since it has no applicability for standards that
use test methods that specify minimum run times or sample volumes, and
numbers of runs, and suggested the EPA use the term ``sample time or
volume'' and make clear that it can be a minimum or an absolute value.
    Response: The EPA does not agree with the commenters' suggestion.
The proposal identified four components associated with demonstrating
compliance via performance testing--the indicator of compliance (for
which the commenters expressed concern), the test method, the averaging
time associated with the test method, and the frequency of conducting
the test--as well as five components associated with demonstrating
compliance via ongoing monitoring. However, the commenters appear to
suggest to expand compliance demonstration techniques beyond testing
and monitoring. To the extent that SIP regulations are developed that
do not rely on performance testing or ongoing monitoring as means for
demonstrating compliance, the EPA agrees that other components,
including emission limitations that identify the pollutant of interest
and units of measurement, as suggested by the commenter, would be
appropriate.
    The EPA believes neither a change in term from ``test method'' to
``measurement method'' nor an additional acknowledgement regarding its
current wording ``specific EPA or other published set of [criteria]''
is needed. The component to which the commenter refers is based on
performance testing; ongoing measurement components are covered as
`measurement technique' in one of the five critical elements for
ongoing measurement.
    The EPA agrees with the commenters that in some circumstances, test
methods rely on sample volumes as opposed to specific durations. The
`averaging time' component of performance tests will be changed to
`sample collection characteristics', where such characteristics will
include averaging time, duration, or sample volume and number of runs,
as applicable. While the EPA does not believe it to be necessary to
identify that the sample collection characteristics could be minima,
maxima, or ranges, the preamble discussion associated with this change
indicates that specific test methods, or regulatory agencies, may
impose restrictions or specific conditions on sample collection
characteristics.
    Comment: Some commenters stated the EPA should make clear that
states can rely on CAM-type parameters as indicators of compliance. The
commenters stated the EPA should make clear that states that follow the
CAM rule model are not required to establish those ``indicators'' as
directly enforceable limitations, as long as the SIP imposes directly
enforceable review and corrective action requirements that will ensure
that the source takes corrective action prior to the point when the
indicator would predict noncompliance with an emission limitation.
    Response: The EPA agrees with the commenters that one way
regulatory authorities have owners or operators of regulated sources
demonstrate compliance via ongoing monitoring is to use a CAM rule-type
approach. Under such an approach, an owner or operator would be able to
establish operating ranges of continuously monitored parameters
determined through concurrent performance testing as indicators of
performance (indicators of compliance are components of performance
testing). Nothing in the CAM rule precludes an owner or operator from
establishing parameters as directly enforceable limitations, and
neither does this rule. The CAM rule-type approach would require owners
or operators who chose parameter monitoring as indicative of compliance
to immediately take corrective action should a measured parameter value
occur outside the demonstrated range associated with compliance.
Moreover, concurrent performance testing and parameter measurement
would be necessary on a periodic basis and may be necessary on a more
frequent basis to reverify or reset a parameter value range. Failure to
take immediate corrective action would constitute a violation.
Moreover, failure of a parameter range to demonstrate compliance when
reverification or resetting performance testing occurred would also
constitute a violation.
    Comment: Commenters agreed that a compliance monitoring provision
must specify a ``measurement technique'' and stated the EPA should
defer to states regarding the most appropriate measurement techniques.
The commenter disagreed that use of CEMS for ``directly enforceable
measurements'' is always preferable.
    Response: The EPA appreciates the commenters' support and notes
that the measurement technique component used in this rule corresponds
to a similarly-named component contained

in the definition of monitoring in the general provisions of 40 CFR
part 63. To the extent that regulatory authorities choose appropriate
measurement techniques, the EPA agrees with the commenter. The EPA
believes the commenters take the language regarding use of directly
enforceable emissions measurements out of context; the EPA said it is
preferred wherever feasible, not that it is always required.
    Comment: Commenters stated the EPA should make clear that
``averaging time'' is only required for measurement techniques that
collect continuous data that will be averaged over some period in order
to assess source operations; i.e., the element is only essential to
certain types of compliance monitoring requirements. The commenters
suggested the EPA should not attempt to impose or require minimum
frequencies in terms of calendar days, months, or year and urged the
EPA to allow states flexibility to determine how best to address
operational variability.
    Response: The EPA disagrees with the commenters, noting that
averaging time remains an important aspect of demonstrating compliance
via ongoing monitoring for all types of monitoring. It remains
important to know how the period over which collected data are used to
determine compliance, whether that period is daily, hourly, or
annually. The EPA has not assigned minimum averaging times that
regulatory authorities must use; however, the EPA expects those
regulatory authorities to select averaging times appropriate to
demonstrate compliance for specific types of sources.
    Comment: Commenters supported the EPA's recommendation that
information demonstrating compliance be made available online for
general public access (80 FR 15448) so that the public can provide the
oversight that the Act contemplates (42 U.S.C. 7604). Other commenters
opposed an absolute requirement that all monitoring, testing, and
reporting be done electronically since many permits are for small
businesses who may not have the capital and technical expertise for
electronic recordkeeping and reporting; commenters recommended that the
EPA change this criterion into a recommendation that electronic means
be used where feasible.
    Response: The EPA agrees that electronic reporting and public
access to information is important. The EPA notes that it is and has
been moving towards electronic emissions reporting from all regulated
sources for some time now. New NSPS and NESHAP require electronic
emissions reporting, and efforts are underway to require existing NSPS
and NESHAP to use electronic emissions reporting.\260\ Consistent with
this approach, and with the approach taken by the next generation of
compliance program,\261\ this rule will assist the shift toward
electronic reporting to make environmental reporting more accurate,
complete, and efficient. Moreover, electronic reporting of emissions
will help us and regulatory authorities better manage information,
improve effectiveness, and improve transparency.
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    \260\ See 80 FR 15099, March 20, 2015.
    \261\ See http://www2.epa.gov/sites/production/files/2014-09/documents/next-gen-compliance-strategic-plan-2014-2017.pdf.
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F. Multi-Pollutant Considerations

1. Summary of Proposal
    The EPA described many benefits of coordinating air quality
planning efforts across a range of air quality programs addressing the
NAAQS, air toxics, and climate change and encouraged states to pursue
multipollutant planning approaches where possible.
2. Final Rule
    The final rule reiterates many of the points made in support of
multipollutant planning efforts in the proposal. Efforts to reduce fine
particle concentrations fit well as part of multi pollutant planning
efforts because of the involvement of PM2.5 precursor gases
(i.e., NOX, SO2, VOC, and ammonia) and direct
PM2.5 emissions in a number of other air quality and climate
issues. NOX and VOC play important roles in atmospheric
chemistry and in the formation of ground-level ozone. Certain VOCs and
constituents of direct PM2.5 are also hazardous air
pollutants. SO2 and NOX emissions, and their
reactions with ammonia to form ammonium sulfate and ammonium nitrate,
have played important roles in acidic deposition, haze in national
parks, and in fine particle formation. Black carbon from direct
PM2.5 emissions is an important short-lived climate
pollutant. Increasing average temperatures due to climate change are
expected to lead to higher ozone concentrations. Many efforts to
address traditional air pollutants have important co-benefits in terms
of reducing emissions of CO2 and other GHGs, and vice versa.
For these reasons, efforts to reduce air pollution to address multiple
objectives can provide important benefits to states, the regulated
community, and the general public.
    Multipollutant planning issues have been an area of strong interest
by scientists and policymakers for many years. In 1995-1997, the EPA
sought recommendations from a federal advisory committee with broad
stakeholder representation on ways to coordinate and make more
efficient the implementation programs for upcoming ozone and
PM2.5 standards and the regional haze program. The National
Academy of Sciences issued ``Air Quality Management in the United
States,'' a report on multipollutant planning issues and
recommendations, in 2004. In June 2007, the EPA's CAA Advisory
Committee (CAAAC) recommended that the agency allow states to integrate
SIP requirements and other air quality goals into a comprehensive
plan.\262\ The recommended plan would demonstrate attainment/
maintenance of multiple NAAQS, accomplish sector-based reductions,
realize risk reductions of HAPs and make improvements in visibility. It
could also be structured to integrate programs addressing land use,
transportation, energy and climate.
---------------------------------------------------------------------------

    \262\ Recommendations to the Clean Air Act Advisory Committee:
Phase II, June 2007, http://www2.epa.gov/caaac/caaac-reports.
---------------------------------------------------------------------------

    The EPA believes that in many cases it can be more efficient for
states to develop integrated control strategies that address multiple
pollutants rather than separate strategies for individual air quality
programs. An integrated air quality control strategy that reduces
multiple pollutants can help ensure that reductions are efficiently
achieved and produce the greatest overall air quality benefits. The EPA
has encouraged states to take a multi-pollutant approach to managing
air quality to the extent possible.
    While the agency encourages states to develop multi-pollutant
plans, it recognizes that certain factors can make such efforts
challenging. For example, the NAAQS are to be reviewed every 5 years,
and any revisions to the standards will lead to a series of
implementation steps required by specific statutory schedules. In some
cases program requirements and deliverables may not be coordinated
easily, but in other situations there are good opportunities for
conducting technical analyses and developing policy approaches that can
have important health and environmental benefits while addressing
multiple key air pollution issues at the same time.
    One such opportunity is the increased use of multi-pollutant
assessments. A multi-pollutant assessment, or one-atmosphere modeling,
is conducted with a single air quality model (such as CMAQ or CAMx)
that is capable of simulating transport and formation of

multiple pollutants simultaneously.\263\ For example, this type of
model can simulate formation and deposition involving pollutants
associated with PM2.5, ozone and regional haze, and it can
include algorithms simulating gas phase chemistry, aqueous phase
chemistry, aerosol formation and acid deposition. This type of model
could also include the formation and deposition of key air toxics and
the chemical interactions that occur with these individual toxic
species to produce PM2.5 and ozone. It can also account for
estimated changes in traditional air pollutant emissions resulting from
programs (such as energy efficiency and renewable energy programs) to
reduce emissions of CO2 and other greenhouse gases.
---------------------------------------------------------------------------

    \263\ Depending on the context, ``multi-pollutant'' can be
defined in different ways. In this context the agency is defining
multi-pollutant modeling as simultaneous modeling of
PM2.5, ozone, key air toxics, and regional haze. Future
multi-pollutant models may include the ability to model a broader
array of air toxics as well as greenhouse gases.
---------------------------------------------------------------------------

    Models and data analysis intended to address PM2.5 could
be beneficial for use in addressing ozone, visibility impairment, and
climate change. States that undertake multi-pollutant assessments as
part of their attainment demonstration have the opportunity to assess
the impact of their PM2.5 strategies on ozone, visibility,
and climate programs to ensure that optimal emission reduction
strategies are developed to the extent possible. This could facilitate
addressing all of these pollutants in a more cost effective manner.
    States may also find it desirable to assess the impact of
PM2.5, ozone, and/or regional haze control strategies on
toxic air pollutants regulated under the CAA or under state air toxic
initiatives. Given the relationships that exist between air toxics and
the formation of PM2.5 and ozone, states may find that
controls can be selected to meet goals for PM2.5 and/or
ozone attainment as well as those of specific air toxic programs.
3. Comments and Response
    Comments: Some commenters urged the EPA to provide assistance to
those states that might be precluded from developing Multi-Pollutant
SIPs due to lack of resources. Other commenters stated the EPA should
support the states' use of various approaches and tools suggested the
EPA make the Control Strategy (CoST) tool fully available, as well as
provide any necessary training to facilitate states' ability to
effectively use the tool. The commenter also suggested that the EPA
entertain the possibility for states to demonstrate that the controls
put in place to comply with multi-pollutant CAIR and CSAPR are valid
and should be accepted as part of attainment demonstrations; allowing
states to credit emissions reductions that have occurred.
    Response: The Control Strategy Tool (CoST) is a component of the
EPA's Emissions Modeling Framework that is a client-server system
developed to support emissions modeling. CoST was developed by the EPA
to model the emissions reductions and engineering costs associated with
control strategies applied to point, area, and mobile sources of air
pollutant emissions to support the analyses of the EPA air pollution
policies and regulations. Links to the software and documentation are
available at the EPA's CoST Web site at http://www3.epa.gov/ttnecas1/cost.htm. Note that because of resource limitations, the EPA is not
able to provide any support for the installation or operation of CoST
outside of the agency.

G. Measures to Ensure Appropriate Protections for Overburdened
Populations

1. Summary of Proposal
    The EPA requested comments on ways that states can provide public
health protection specifically for overburdened populations when
preparing attainment plans for the PM2.5 NAAQS.
2. Final Rule
    Environmentally overburdened, underserved, and economically
distressed communities may be subject to a higher risk of pollutant-
related health effects than the general population because they may be
exposed to higher pollutant concentrations than the general population;
they may experience a larger health impact at a given pollutant
concentration; or they may be adversely affected by lower pollutant
concentrations than the general population.\264\ Thus, the NAAQS review
process inherently takes into consideration appropriate environmental
justice factors as part of the standard-setting process for each
pollutant.
---------------------------------------------------------------------------

    \264\ See EPA 2011. Policy Assessment for the Review of the
Particulate Matter National Ambient Air Quality Standards, Office of
Air Quality Planning and Standards, Research Triangle Park, NC, EPA
452/R-11-003, April 2011.
---------------------------------------------------------------------------

    Section 109(d) of the CAA requires the EPA to periodically review
(every 5 years) the science upon which the standards are based and the
standards themselves. The policy assessment for the 2012 PM NAAQS
review (U.S. EPA, 2011a, p. 2-60) observed that the highest
concentrations of PM2.5 in an area tend to be measured at
monitors located in areas where the surrounding populations are more
likely to live below the poverty line and to have higher percentages of
minorities. In its 2012 review of the PM NAAQS, the EPA revised the
primary annual PM2.5 standard by lowering the level to 12.0
micrograms per cubic meter ([micro]g/m\3\) to provide increased
protection against health effects associated with long- and short-term
PM2.5 exposures.\265\ The agency also (1) revised the form
of the primary annual PM2.5 standard to eliminate the
spatial averaging provisions to avoid potential disproportionate
impacts on at-risk populations; and (2) directed states to relocate a
limited number of existing monitors to near-roadway sites in large
urban areas. Both of these actions were informed by scientific evidence
that underscored the potentially disproportionate exposure to high
PM2.5 concentrations and therefore disproportionate risk to
low-income and minority populations.
---------------------------------------------------------------------------

    \265\ 78 FR 3086 (January 15, 2013).
---------------------------------------------------------------------------

    In conjunction with these revisions, the EPA retained the primary
24-hour PM2.5 standard, as revised in 2006 (71 FR 61144,
October 17, 2006), to provide supplemental protection against health
effects associated with short-term PM2.5 exposures,
especially in areas with high peak PM2.5 concentrations.
This suite of primary annual PM2.5 standards provides
increased public health protection, including the health of at-risk
populations which include children, older adults, persons with pre-
existing health and lung disease, and persons of lower socioeconomic
status, against a broad range of PM2.5-related effects that
include premature mortality, increased hospital admissions and
emergency department visits, and development of chronic respiratory
disease.\266\
---------------------------------------------------------------------------

    \266\ In the final 2012 PM NAAQS rule, based on information
presented in the Integrated Science Assessment for Particulate
Matter (U.S. EPA, 2009, sections 2.2.1 and 8.1.7), the EPA made a
finding that persons with lower socioeconomic status are at
increased risk for experiencing adverse health effects related to PM
exposures (78 FR 3085, January 15, 2013, at page 3104). Persons with
lower socioeconomic status (SES) have been generally found to have a
higher prevalence of pre-existing diseases, limited access to
medical treatment, and increased nutritional deficiencies, which can
increase this population's risk to PM-related effects (77 FR 38911,
June 29, 2012).
---------------------------------------------------------------------------

    Relationship between direct PM2.5 emissions and PM2.5 precursor

emissions reductions and at-risk populations. Sources of direct PM
emissions have their greatest impact on PM2.5 concentrations
and public health in the general vicinity of the source (e.g., within
10 miles), while sources of precursor emissions can contribute to
PM2.5 concentrations more than 100 miles away and are
considered to have a more regional impact. To date, state
PM2.5 attainment plans have generally relied to a greater
extent on reductions of precursor pollutants rather than on reductions
of direct PM2.5 emissions. Studies show, however, that on a
per ton basis, the reduction of a ton of direct PM2.5
emissions leads to greater health benefits than the reduction of a ton
of SO2 or NOX.\267\
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    \267\ See Fann, N., Fulcher, C., and B. Hubbell, 2009. The
Influence of location, source, and emission type in estimates of the
human health benefits of reducing a ton of air pollution. Air
Quality, Atmosphere & Health. Volume 2, Number 3, 169-176, June
2009. See also Fann et al., 2011. Maximizing health benefits and
minimizing inequality: incorporating local-scale data in the design
and evaluation of air quality policies. Society for Risk Analysis,
vol. 31, no. 6, p. 908-922, June 2011.
---------------------------------------------------------------------------

    The process for developing attainment plans for the current and
future PM2.5 NAAQS presents a potential opportunity to
target the health protections afforded by the NAAQS, as the EPA expects
that attainment for the 2012 PM2.5 NAAQS and future
PM2.5 NAAQS in nonattainment areas with the most severe
pollution problems may need to give greater emphasis to reducing direct
PM2.5 emissions in combination with efforts already underway
to further reduce precursor emissions. Placing greater emphasis on
reducing emissions from sources of direct PM2.5 (e.g.,
certain industrial facilities located in more densely populated areas;
areas with high motor vehicle and other diesel engine emissions, such
as rail yards and near major roadways; and, areas with high wood smoke
emissions) could provide the added benefit of reducing exposure to
PM2.5 in low-income and minority communities.
    Options for states to consider to ensure appropriate protections
from PM2.5 exposure for overburdened populations. The EPA believes that
states have sufficient flexibility and discretion under the CAA in
implementing their attainment strategies to focus resources on
controlling those sources of emissions that directly and adversely
affect low-income and other at risk populations. By reducing impacts on
at-risk populations, states can maximize health benefits, thereby
creating greater net benefits for the state in a cost-effective
manner.\268\ In addition, reducing adverse impacts to low-income and
minority populations advances the environmental justice goal of fair
treatment for these populations.
---------------------------------------------------------------------------

    \268\ Wesson, K., Fann, N., Morris, M, Fox, T., Hubbell, T.,
2010. A multipollutant, risk-based approach to air quality
management. Case study for Detroit. Atmospheric Pollution Research,
1, 296-304. The study compared air quality control strategies and
concluded that the multi-pollutant, risk-based approach was able to
produce approximately two times greater monetized benefits through
avoided health impacts and was more cost effective than a pollutant-
by-pollutant approach.
---------------------------------------------------------------------------

    There are a number of actions that states could take to focus
resources in this way. Some of these actions can help identify areas
where additional ambient monitoring may be needed in low income and
overburdened communities. Such information can be used to support
updates to the state's annual monitoring plan.
    Screening is a useful first step in understanding or highlighting
locations that may be candidates for further review. The EPA has
developed EJSCREEN, a public screening tool that allows users to access
high-resolution environmental and demographic information for locations
in the United States, and compare their selected locations to the rest
of the state, the EPA region, or the nation. The tool may help users
identify areas with minority and/or low-income populations, potential
environmental quality issues, a combination of environmental and
demographic indicators that is greater than usual, and other factors
that may be of interest. Other examples of actions to support updates
to the annual monitoring plan include:

     Develop databases and online mapping tools that enable
users (including state staff, public, and the regulated community)
to understand where sources of direct PM2.5 emissions are
located and where new or modified sources of emissions could have
potential impacts on low income and other overburdened communities;
     Incorporate existing mapping tools that identify target
areas in the attainment plan development process and related
actions; and,
     Analyze emissions data, ambient data, and available
modeling to identify potential unmonitored PM2.5 hotspots
in areas with a high percentage of low income, minority or
indigenous persons (see Section III.E of this preamble for further
discussion of this option).

    Once target areas for addressing these sensitive population needs
within a nonattainment area have been identified, the state could
consider taking any of the following actions, which help target
emissions reductions that may be needed to attain the PM2.5
NAAQS:

     Prioritize the selection of control measures that
target reductions of direct PM2.5, particularly from
sources located in ``at-risk'' areas as part of the state's RACM and
RACT analysis (for Moderate nonattainment areas) or BACM and BACT
analysis (for Serious nonattainment areas), as well as other
measures needed to demonstrate attainment (see Sections III.D and
V.D of this preamble, respectively, of this preamble for further
discussion of this option);
     Improve the understanding of the potential impact of
minor sources by improving or generating an emissions inventory for
such minor sources, including sources that are not currently
required to report emissions, to generate options on how emissions
can be reduced in the target area;
     Design voluntary programs to reduce VMT and mobile
source-related PM2.5 emissions (e.g., diesel retrofits);
     Incorporate environmental justice criteria into the
alternatives analysis to ensure appropriate siting and require
cumulative impact studies for proposed projects;
     Eliminate exemptions from and/or lower thresholds for
minor source permitting;
     Prioritize targeted enforcement strategies; and
     Develop a list of potential supplemental environmental
projects (SEPs) \269\ that could be applied in the target area.
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    \269\ For more information on SEPs, go to https://www.epa.gov/enforcement/supplemental-environmental-projects-seps.

    In addition to the previous steps, states could increase
opportunities for meaningful involvement of community groups in
attainment plan development, annual monitoring network plan reviews,
and permitting processes \270\ for at-risk and minority populations by
taking the following steps:
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    \270\ See 78 FR 27220 (May 9, 2013) notice of availability,
``EPA Activities To Promote Environmental Justice in the Permit
Application Process.''

     Develop advisory boards and/or develop enhanced notice-
and-comment requirements for low income and minority communities to
assure meaningful involvement relative to projects that impact their
communities;
     Provide special notice of important actions affecting
target areas in appropriate languages and with attention to cultural
barriers;
     Provide advance notification for low income and
minority communities of upcoming opportunities for public comment on
SIPs, ambient air monitoring plans, and other relevant actions such
as permit actions;
     Maintain multi-lingual Web sites and offer translators
for public meetings and hearings; and,
     Coordinate with the state's EJ coordinator, if
applicable, to assist with outreach efforts.
3. Comment and Response
    Comment: Some commenters supported the EPA's recommendations for
measures to ensure protections for

overburdened communities, but stated that the EPA's proposal to allow
areas to ignore near-roadway monitors is inconsistent with these
objectives. The commenter stated that communities near heavily
trafficked areas tend to be disproportionately low-income minority
communities that suffer from disproportionately higher PM2.5
exposure risks; and that the EPA and states should address the
information gaps that disempower these communities in their ability to
protect themselves from pollution sources. The commenter also stated
that making sources disclose and report compliance information and
providing that information in easy to access formats would go a long
way to improve the ability of these communities to be informed of their
risks and to assure compliance in their communities.
    Response: The EPA agrees that near-road monitoring data should not
be ignored in future attainment planning. However, the EPA wishes to
clarify that the statements in the proposal referenced the fact that
the near-road monitors were not required to be in place before January
1, 2015. Compliance with the PM2.5 standards is based on 3
years of complete, quality-assured data at a monitor. Thus, the
earliest that these monitors would have valid design values would be in
early 2018 (based on data from 2015-2017). This timing makes it
unlikely that sufficient data from these monitors will be available to
be considered in attainment demonstrations that are due in 2016. In
addition, the base modeling year of the attainment demonstration may
pre-date the startup date of the near-road monitor(s). In this case, it
may be possible to consider the near-road data in the attainment
demonstration, but the recommended default projection methodology may
not be applicable (since the time period of the near-road data may not
correspond to the 5 year time period centered about the base modeling
year, as recommended in the modeling guidance). Additionally, near-road
PM2.5 monitors are only required in the 27 largest
metropolitan areas of the country, and some PM2.5
nonattainment areas may not have any near-road monitoring sites. Thus,
when complete data from near-road PM2.5 ambient monitors
become available, the data should be used by states and the EPA for all
aspects of the NAAQS implementation process, from attainment planning
to the determination of attainment, in a manner similar to any other
quality-assured PM2.5 monitoring data. States should consult
with the appropriate the EPA regional office to determine how and when
near-road data should be used in the PM2.5 NAAQS
implementation process for specific nonattainment areas.
    With regard to the comment about having easy access to facility
compliance information, the EPA directs the commenter to the
Enforcement and Compliance History Online Web site to search for
facilities to assess compliance with environmental regulations. The
site provides the ability to investigate pollution sources, examine and
create enforcement-related maps, or explore an individual state's
performance. As noted earlier in this section, the EJSCREEN tool can
also provide important information about estimated pollution impacts in
specific communities.

H. Tribal Issues

    The 1998 Tribal Authority Rule (TAR) (40 CFR part 49), which
implements section 301(d) of the CAA, gives tribes the option of
developing Tribal Implementation Plans (TIPs). Specifically, the TAR
provides for the tribes to be treated in the same manner as a state in
implementing certain sections of the CAA. However, tribes are not
required to develop implementation plans. The EPA determined in the TAR
that it was inappropriate to treat tribes in a manner similar to a
state with regard to specific plan submission and implementation
deadlines for the NAAQS-related requirements, including, but not
limited to, such deadlines in CAA sections 110(a)(1), 172(a)(2), 182
187, and 191. See 40 CFR 49.4(a). In addition, the EPA determined it
was not appropriate to treat tribes similarly to states with respect to
provisions of the CAA requiring as a condition of program approval the
demonstration of criminal enforcement authority or providing for the
delegation of such criminal enforcement authority. See 40 CFR 49.4(g).
To the extent a tribe is precluded from asserting criminal enforcement
authority, the federal government will exercise primary criminal
enforcement responsibility. See 40 CFR 49.8. In such circumstances,
tribes seeking approval for CAA programs provide potential
investigative leads to an appropriate federal enforcement agency.
    If a tribe elects to do a TIP, the agency will work with the tribe
to develop an appropriate schedule that meets the needs of the tribe
and does not interfere with the attainment of the NAAQS in other
jurisdictions. The tribe developing a TIP can work with the EPA
Regional Office on the appropriateness of addressing RFP and other
substantive SIP requirements that may or may not be appropriate for the
tribe's situation.
    The CAA and the TAR provide tribes opportunity and flexibility, but
not the obligation to develop a TIP to address the NAAQS. If a tribe
elects to develop a TIP, the TAR offers flexibility for the tribe to
identify and implement on a case-by-case basis only those CAA programs
or reasonably severable program elements needed to address their
specific air quality problems. In the TAR, the EPA described this
flexible implementation approach as a modular approach. Each tribe may
evaluate the particular activities, including potential sources of air
pollution within the exterior boundaries of its reservation (or within
non-reservation areas for which it has demonstrated jurisdiction), that
cause or contribute to its air pollution problem. A tribe may adopt
measures for controlling those sources of PM2.5-related
emissions, as long as these elements of the TIP are reasonably
severable from other CAA requirements. A TIP must include regulations
designed to solve specific air quality problems for which the tribe is
seeking the EPA's approval, as well as a demonstration that the tribal
air agency has the authority from the tribal government to develop and
run their program, the capability to enforce their rules, and the
resources to implement the program they adopt. In addition, the tribe
must receive an eligibility determination from the EPA to be treated in
the same manner as a state for the particular matter at issue and to
receive authorization from the EPA to run a CAA program.
    The EPA would review and approve, where appropriate, these TIPs as
one step of an overall air quality plan to attain the NAAQS. A tribe
may step in later to add other elements to the plan, or the EPA may
step in to fill gaps in the air quality plan as necessary or
appropriate. In approving a TIP, the agency would evaluate whether the
plan appropriately coordinates with the overall air quality plan for an
area when tribal lands are part of a multi-jurisdictional area.
    Because many PM2.5 nonattainment areas will include
multiple jurisdictions, and in some cases both Indian country and state
lands, it is particularly important for the tribes and the states to
work together to coordinate their planning efforts. States need to
incorporate Indian country emissions in their base emissions
inventories if Indian country is part of an attainment or nonattainment
area.\271\ Tribes and

states should coordinate their planning activities as appropriate to
ensure that neither is adversely affecting attainment of the NAAQS in
the area as a whole. Coordinated planning in these areas will help
ensure that the planning decisions made by the states and tribes
complement each other and that the nonattainment area makes reasonable
progress toward attainment and ultimately attains the applicable
PM2.5 NAAQS. In reviewing and approving individual TIPs and
SIPs, the EPA will determine if together they are consistent with the
overall air quality needs of an area.
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    \271\ On January 17, 2014, the United States Court of Appeals
for the District of Columbia Circuit issued a decision vacating the
EPA's 2011 rule titled ``Review of New Sources and Modifications in
Indian Country'' (76 FR 38748, July 1, 2011) with respect to non-
reservation areas of Indian country (See Oklahoma Department of
Environmental Quality v. EPA, 740 F.3d 185 (D.C. Cir. 2014)). Under
the court's reasoning, with respect to CAA state implementation
plans, a state has primary regulatory jurisdiction in non-
reservation areas of Indian country (i.e., Indian allotments located
outside of reservations and dependent Indian communities) within its
geographic boundaries unless the EPA or a tribe has demonstrated
that a tribe has jurisdiction over a particular area of non-
reservation Indian country within the state.
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    To date, very few tribes have submitted for the EPA's approval TIPs
covering areas over which they have jurisdiction. In the absence of a
TIP, the EPA is authorized under the TAR to implement CAA programs in
such areas as necessary or appropriate. For example, an unhealthy air
quality situation on an Indian reservation may require the EPA to
develop a FIP to reduce emissions from sources on the reservation.
Likewise, if the agency determines that sources in an area under tribal
jurisdiction could interfere with a larger nonattainment area meeting
the NAAQS by its attainment date, it would develop a FIP for those
sources in consultation with the tribe as necessary or appropriate.
    States have an obligation to notify other states in advance of any
public hearing(s) on their state plans if such plans will significantly
impact such other states. 40 CFR 51.102(d)(5). Under section 301(d) of
the CAA and the TAR, tribes may become eligible to be treated in a
manner similar to states (TAS) for this purpose. Affected tribes with
this status must also be informed of the contents of such state plans
and given access to the documentation supporting these plans. In
addition to this mandated process, the EPA encourages states to extend
the same notice to all affected tribes, regardless of their TAS status.
    Executive Orders and the EPA's Indian policies generally call for
the EPA to coordinate and consult with tribes on matters that affect
tribes. Executive Order 13175, titled, ``Consultation and Coordination
with Indian Tribal Governments'' requires the EPA to develop a process
to ensure ``meaningful and timely input by tribal officials in the
development of regulatory policies that have Tribal implications.'' In
addition, the EPA's policies include the agency's 1984 Indian Policy
relating to Indian tribes and implementation of federal environmental
programs, the 2014 Office of Air and Radiation's ``Handbook for
Interacting with Tribal Governments,'' and the ``EPA Policy on
Consultation and Coordination with Indian Tribes.'' Consistent with
these policies, the EPA intends to meet with tribes on activities
potentially affecting the attainment and maintenance of the current and
future PM2.5 NAAQS in Indian country, including agency
actions on SIPs. As such, it would be helpful for states to work with
tribes with land that is part of the same air quality area during the
SIP development process and to coordinate with tribes as they develop
their SIPs.

I. Voluntary Programs for Reducing Ambient PM2.5

1. PM Advance Program
    The EPA believes there are significant advantages for states,
tribes and local agencies to take steps to reduce direct
PM2.5 emissions and emissions of PM2.5 precursors
as early as possible. First and foremost, early reductions help to
achieve cleaner air sooner, and help to ensure continued health
protection. Second, early steps could help an area avoid a
nonattainment designation in the first place, or for an area eventually
designated as nonattainment, early reductions could help bring the area
back into attainment sooner, which may lead to qualifying for a CDD and
subsequent suspension of attainment planning requirements as described
in Section IX.C of this preamble. In addition, early action to improve
air quality can help an eventual nonattainment area, particularly an
area that has never been designated nonattainment before, to establish
working relationships between key stakeholders. The EPA's expectation
is that early actions to reduce emissions in such areas would be less
resource-intensive than actions taken once a nonattainment designation
has been made, since at that point the implementation of controls would
need to occur in conjunction with actions to comply with other
requirements such as nonattainment NSR and transportation conformity.
    In January 2013, the EPA began a new early emissions reduction
program for attainment areas called ``PM Advance,'' which is much like
the related ``Ozone Advance'' program that began in April 2012. For
additional information and a list of areas that are currently
participating in the program, see https://www.epa.gov/advance.
2. Residential Wood Smoke Programs
    The EPA recognizes that residential wood smoke is a concern for
many nonattainment areas. The EPA estimates that wood stoves, indoor
wood furnaces, hydronic heaters and fireplaces emit more than 382,000
tons of PM2.5 into the air throughout the country each
year--mostly during the winter months. Residential wood smoke can
increase fine particle pollution to levels that cause significant
health concerns (e.g., asthma attacks, heart attacks, premature death).
Wood smoke causes many counties throughout the U.S. to either exceed
the national health-based standards for fine particles, or places them
on the cusp of exceeding the standards. Because wood stoves, hydronic
heaters and other similar appliances can be used around the clock in
residential areas, they can cause significant and varying health and
quality of life issues.
    To reduce fine particle pollution, many PM2.5
nonattainment areas will need to address residential wood smoke. The
EPA has developed the ``Strategies for Reducing Residential Wood
Smoke'' document that provides education and outreach tools,
information on regulatory approaches to reduce wood smoke, as well as
information about voluntary programs that communities around the
country have used.\272\ In addition, it includes methods for
calculating emissions reductions, funding ideas and the basic
components of a wood smoke reduction plan that can be adopted into a
SIP as an enforceable control measure.\273\ To access the document, go
to https://epa.gov/burnwise/burn-wise-strategies-reducing-residential-wood-smoke. For

more information on the EPA's wood smoke reduction program, see https://www.epa.gov/burnwise.
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    \272\ On February 3, 2015, the EPA strengthened the New Source
Performance Standards (NSPS) for new residential wood heaters and
established NSPS for other new wood heaters, including outdoor and
indoor wood-fired boilers (also known as hydronic heaters). The
standards will reduce emissions of direct PM2.5 as well
as carbon monoxide, VOC, air toxics (including formaldehyde, benzene
and polycyclic organic matter), and black carbon. See http://www2.epa.gov/residential-wood-heaters.
    \273\ For further guidance on incorporating voluntary measures
into a SIP, see ``Incorporating Emerging and Voluntary Measures in a
State Implementation Plan (SIP).'' U.S. EPA. Office of Air and
Radiation. September 2004. Available at http://www3.epa.gov/ttn/caaa/t1/memoranda/evm_ievm_g.pdf.
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J. Improved Stationary Source Emissions Monitoring

1. Summary of Proposal
    For purposes of demonstrating compliance with the EPA's air quality
regulatory requirements, the EPA, states, and sources rely on two basic
types of monitoring: ambient air quality monitoring and stationary
source emissions monitoring. Ambient air quality monitoring entails
collecting and measuring samples of criteria pollutants in ambient air
to evaluate air quality as compared to clean air standards and
historical information. Stationary source emissions monitoring, on the
other hand, entails collecting and using measurement data (or other
information) from individual stationary sources to demonstrate
compliance with emissions standards, to assess process or control
device performance, or to verify work practices. While ambient air
quality monitoring is used to assess compliance with the NAAQS,
stationary source emissions monitoring is used to assess compliance
with source-specific regulations under programs like the New Source
Performance Standards (NSPS), the National Emissions Standards for
Hazardous Air Pollutants (NESHAP), the compliance assurance monitoring
(CAM) program, the title V air operating permits program, and the acid
deposition control program, as well as specific SIP control measures.
    Accurate stationary source emissions monitoring is also critical
for the purposes of developing accurate emissions inventories and in
order to identify appropriate control measures to reduce emissions from
stationary sources. In addition, after control measures are in place,
stationary source emissions monitoring provides process and control
device performance information to the facility operator so that
appropriate corrective action can be taken if indicated that emission
levels may exceed applicable thresholds. Thus, appropriate stationary
source emissions monitoring requirements, like the control measures
with which they are associated, are a fundamental element of an
approvable SIP.
    Because of the important role that effective stationary source
emissions monitoring can play in informing the development of
attainment strategies for PM2.5 NAAQS nonattainment areas,
the EPA is interested in applied best practices for stationary source
emissions monitoring that could be included in guidance for other
stationary sources and states. As a result of this interest, the EPA
sought to gather information about ways to make the source emissions
monitoring data collection process easier and more transparent. In the
proposal, the EPA therefore asked for information regarding appropriate
examples and supporting data from individual sources and states with
experience in this area to inform such future guidance. The EPA sought
comment on specific topics and questions regarding source monitoring
techniques and asked commenters to submit any examples of improved