of the PM2.5 plan precursors. For example, it is likely that
many PM2.5 plans will include SO2 as a plan
precursor. However, emissions of SO2 from on-road sources
are usually low compared to stationary sources. The transportation
conformity rule allows for the state to determine through its SIP
development process if it is necessary to establish motor vehicle
emissions budgets for SO2. See 40 CFR 93.102(b)(2)(v). On
the other hand, if a state provides a precursor demonstration approved
by the EPA which shows that VOCs do not have a significant contribution
to PM2.5 levels in a particular nonattainment area, then a
motor vehicle emissions budget for VOCs would not need to be
established for the area for transportation conformity purposes. A
motor vehicle emissions budget for the purposes of a PM2.5
RFP plan is that portion of the total allowable emissions allocated to
on-road sources as defined in the submitted RFP plan for the relevant
years as described earlier.\119\ Such motor vehicle emissions budgets
will be calculated using the latest planning assumptions and the latest
approved motor vehicle emissions model available at the time that the
attainment plan is developed, unless the EPA approves the state's use
of an alternative model.\120\
---------------------------------------------------------------------------

    \118\ For more information on PM2.5 precursor
requirements, see CAA section 93.102(b)(1) and (b)(2)(iv) and (v) of
the transportation conformity rule. See also the May 6, 2005, final
transportation conformity rule that addressed requirements for
PM2.5 precursors. (70 FR 24280).
    \119\ A state would also establish motor vehicle emissions
budgets for an area's attainment year. Those budgets would be the
motor vehicle emissions that the SIP establishes as being necessary
to attain the NAAQS.
    \120\ If an area includes re-entrained road dust in the motor
vehicle emissions budget, the latest approved version of AP-42
should be used unless the EPA has approved an alternative model for
the area.
---------------------------------------------------------------------------

    c. Comments and Responses. Comment: Some commenters stated that
since RFP is one of the general attainment plan provisions listed in
CAA section 172(c), the EPA's proposal to require motor vehicle
emissions budgets as part of RFP plans extends beyond just the
implementation of the PM2.5 NAAQS and, as a result, this
proposal should be presented within the context of a revision to the
conformity rule itself and not just this PM2.5
implementation rule.
    Response: The EPA disagrees with the commenters. The transportation
conformity rule already states that motor vehicle emissions budgets
come from control strategy SIPs.\121\ Additionally, the transportation
conformity rule defines control strategy SIPs as RFP plans and
attainment demonstrations. It goes further to say that control strategy
SIPs include the SIPs required by CAA sections 172(c), 189(a)(1)(B) and
189(b)(1)(A). The requirement in this PM2.5 SIP Requirements
Rule does not amend the transportation conformity rule; it merely
explains what is already required.
---------------------------------------------------------------------------

    \121\ 40 CFR 93.101.
---------------------------------------------------------------------------

4. Geographic Coverage of Emission Sources for RFP
    a. Summary of Proposal. The EPA proposed that the RFP demonstration
to be included with a state's PM2.5 nonattainment area plan
must include emissions only for sources located in the nonattainment
area, and not from an area larger than the nonattainment area. This
proposed policy approach differed from the remanded 2007
PM2.5 implementation rule. As explained in the proposal, the
difference was due to the evolution of policy on a similar RFP issue in
the ozone NAAQS implementation program that stemmed in part from a
petition for reconsideration and a DC Circuit

decision on the November 2005 Phase 2 Ozone Implementation Rule. The
EPA received a similar petition for reconsideration of the 2007
PM2.5 Implementation Rule, which dealt with the EPA's
interpretation of the statutory RFP requirements to allow a state to
take ``credit'' for emissions reductions from outside the nonattainment
area when addressing RFP in its attainment plan.\122\ The EPA granted
the petition for reconsideration on this issue in 2010, after the DC
Circuit issued its decision on litigation on the Phase 2 Ozone
Implementation Rule.123 124 In light of these developments,
the proposal indicated that the EPA now believes the best reading of
the statute is that the CAA does not allow for a state to include
emissions reductions from sources outside a nonattainment area when
developing the plan to meet the CAA section 172(c)(2) RFP requirements
for a PM2.5 nonattainment area.
---------------------------------------------------------------------------

    \122\ This same petition raised concerns regarding the criteria
used to determine the economic feasibility of controls being
considered for RACT for the 1997 PM2.5 NAAQS. See
``Petition for Reconsideration,'' filed by Paul Cort, Earthjustice,
on behalf of the American Lung Association, Medical Advocates for
Healthy Air, Natural Resources Defense Council, and the Sierra Club
(June 25, 2007). A copy of the petition is in the docket for this
action.
    \123\ Letter dated May 13, 2010, from Gina McCarthy to David S.
Baron and Paul Cort, Earthjustice. A copy of the letter is located
in the docket for this action.
    \124\ See NRDC v. EPA, 571 F.3d 1245 (D.C. Cir. 2009).
---------------------------------------------------------------------------

    b. Final Rule. The EPA is finalizing that the RFP demonstration to
be included with a state's PM2.5 nonattainment area plan
must include emissions only for sources located in the nonattainment
area, and not from an area larger than the nonattainment area.
Commenters disagreed with limiting the RFP demonstration to include
emissions only for sources located in the nonattainment area stating
that some areas are so dominated by upwind emissions and local sources
over which they have no control, such as motor vehicles, that they
cannot demonstrate RFP. One of these commenters noted they have
provided extensive comments on this issue in connection with the EPA's
proposal for the recent ozone implementation rule and incorporated by
reference their prior comments. Other commenters agreed with the
proposal and stated the EPA's conclusion is compelled by CAA sections
172(c)(1), 172(c)(3) and 189(d), which all focus on emissions and
reductions in the area.
    In the preamble to the remanded 2007 PM2.5
Implementation Rule, the EPA allowed states to incorporate reductions
of NOX and SO2 emissions up to 200 km from
outside the nonattainment area (and potentially for reductions of VOC
or ammonia) into their RFP plan when certain conditions were met. This
policy was included in the 2007 PM2.5 Implementation Rule in
part to be consistent with a similar RFP policy for NOX and
VOC that was included in the November 2005 Phase 2 ozone NAAQS
implementation rule, which provided guidance for states on implementing
the 1997 ozone NAAQS.\125\ Under this policy, if a state intended to
include emissions reductions from outside the nonattainment area in the
RFP plan, the state would need to take on the additional accounting
work associated with developing: (i) An expanded baseline emissions
inventory for the entire geographic area and, (ii) a projected
attainment year inventory for this expanded area outside the boundaries
of the designated nonattainment area. Development of these more
extensive inventories would likely have involved a substantial amount
of additional time and resources. In addition, the state would have
needed to provide information supporting its decision regarding how far
outside the nonattainment area the RFP inventory should extend. While
this ``outside the nonattainment area'' RFP approach was theoretically
available to states in developing their PM2.5 attainment
plans due in 2008, there were no states to the agency's knowledge that
elected to follow this approach.
---------------------------------------------------------------------------

    \125\ See Phase 2 Ozone Implementation rule, 70 FR 71612
(November 29, 2005).
---------------------------------------------------------------------------

    Both the Phase 2 ozone implementation rule and the 2007
PM2.5 Implementation Rule were challenged on several issues.
With regard to the Phase 2 ozone implementation rule, the EPA granted a
petition for reconsideration and ultimately issued a final notice of
reconsideration in June 2007. In November 2008, the U.S. Court of
Appeals for the DC Circuit heard oral argument concerning multiple
petitions for judicial review of the Phase 2 ozone rule and the notice
of reconsideration. One of the issues in that case involved whether
compliance by EGUs with a regional emissions trading program could be
considered to meet the RACT requirement for those sources located in a
nonattainment area. In its July 2009 decision, the court emphasized
that: ``The RACT requirement calls for reductions in emissions from
sources in the area; reductions from sources outside the nonattainment
area do not satisfy the requirement. Accordingly, participation in the
NOX SIP call would constitute RACT only if participation
entailed at least RACT-level reductions in emissions from sources
within the nonattainment area.''
    In light of this court decision, the EPA has determined that the
best reading of the statute is that the term ``sources in the area''
should be interpreted in the same manner as ozone. The term appears in
CAA section 182 (requirements for ozone nonattainment areas) with
regard to RFP as well as RACT. The decision on the Phase 2 ozone rule
found that CAA section 182(b)(2) requires that a SIP must provide for
implementation of RACT (under CAA section 172(c)) for emissions sources
``in the area,'' meaning in the nonattainment area. Similarly, the EPA
position is that when CAA section 182(b)(1)(A)-(B) defines baseline
emissions for RFP as ``the total amount of actual VOC or NOX
emissions from all anthropogenic sources in the area,'' this also means
sources in the nonattainment area.
    Turning to PM2.5, the EPA has determined that the DC
Circuit's interpretation of the phrase ``sources in the area'' should
apply to RACT and RFP requirements for both the ozone NAAQS and the
PM2.5 NAAQS. In particular, for PM2.5, the
statutory language at CAA section 171(1) defines RFP in terms of
``reductions in emissions'' required in an attainment plan, which the
EPA interprets as being directly linked to the baseline emissions
inventory for sources located in a PM2.5 nonattainment area.
The baseline emissions inventory is the foundation for the attainment
plan. The emissions inventory requirement of CAA section 172(c)(3)
explicitly requires that the attainment plan inventory include all
sources of the relevant pollutants ``in such area,'' which is a clear
reference to the designated nonattainment area. Given that the baseline
inventory must reflect the emissions ``in such area,'' and that this
inventory provides the starting point for a state's RFP analysis, in
which the state must calculate generally linear progress in emissions
reductions that will lead to attainment of the NAAQS in the area, the
EPA believes it is appropriate that a state should consider only
sources located within the nonattainment area when conducting its
analysis to determine the annual emissions reductions necessary for
demonstrating RFP.
    Beyond the Court's interpretation, the EPA believes that the most
appropriate approach with regard to the geographic area required to be
covered for demonstrating RFP in a PM2.5 attainment plan
also should be limited to the nonattainment area for two other

reasons. First, the EPA believes that it makes policy sense for the
PM2.5 implementation rule approach to be consistent with the
approach finalized in the 2008 NAAQS for Ozone: SIP Requirements
rule.\126\ Second, a policy allowing the geographic area of the RFP
plan to be larger than the nonattainment area would conflict with a key
provision of subpart 4 that requires annual incremental reductions in
emissions from sources within the nonattainment area. Under subpart 4,
an area that fails to attain the standard by the Serious area
attainment date is then subject to the provisions of CAA section
189(d). Section 189(d) of the CAA specifies that the state must submit
a plan revision within 12 months which provides for ``an annual
reduction in PM10 or PM10 precursor emissions
within the area of not less than 5 percent of the amount of such
emissions as reported in the most recent inventory prepared for such
area'' (emphasis added). Therefore, the EPA is finalizing an RFP policy
approach that is consistent with CAA section 189(d).
---------------------------------------------------------------------------

    \126\ See 80 FR 12264.
---------------------------------------------------------------------------

    c. Comments and Responses. Comment: Some commenters supported the
EPA's general guidance for developing the RFP demonstration. In
particular, these commenters agreed with the EPA's interpretation of
the CAA to require that emissions reductions for purposes of meeting
the RFP requirement must come from sources within the designated
nonattainment area. Thus, the commenters supported the EPA's proposal
that the RFP demonstration submitted by states as a part of the
attainment plan cannot take credit for emissions reductions occurring
outside the nonattainment area to meet the RFP requirement. These
commenters asserted that the EPA's conclusion is compelled by sections
172(c)(1), 172(c)(3) and 189(d), which all focus on emissions and
reductions in the designated nonattainment area. The commenters further
stated the EPA has not identified any rational way for states to pick
and choose what sources and related emissions outside the designated
nonattainment area would need to be included in inventories and
attainment planning in order to rationally measure RFP.
    Other commenters disagreed with the EPA's interpretation of the CAA
on this issue and advocated that the EPA should provide an option for
states to meet the RFP requirement with emissions reductions from
sources outside the designated nonattainment area in addition to
reductions from sources inside the area. One commenter suggested the
EPA should provide this option to states and also consider alternatives
to simplify the ``overly complicated analysis'' needed to support this
option in the now superseded 2007 PM2.5 implementation rule.
The comment did not address the consistency of such an interpretation
of the RFP requirements with the statute.
    Another commenter asserted that the EPA should interpret the
statute to permit states to meet the RFP requirement through emissions
reductions from sources outside the designated area based upon several
practical arguments. The commenter stated that, as the PM2.5
standards become lower and reductions from sources within a designated
nonattainment area become more challenging to find, it may be necessary
to obtain emissions reductions from sources beyond the designated area
in order to attain the NAAQS. According to the commenters, some
nonattainment areas are so dominated by emissions from outside the area
and from local sources over which they have no control that they cannot
demonstrate RFP, even though they could demonstrate timely attainment
due to reductions from sources outside the nonattainment area. The
commenters thus argued that the EPA should provide states with the
option to meet the RFP requirement with emissions reductions from
sources outside the nonattainment area in cases where they believe it
would be unreasonable or impossible to do so only with emissions
reductions from within the nonattainment area.
    In response to the EPA's request for comment on any potential legal
basis for authorizing states to meet the RFP requirement with emissions
reductions from outside the nonattainment area, the commenter suggested
potential theories. The primary legal theory was that EPA should by
regulation redefine the term ``area'' for purposes of the RFP
requirement so that it would encompass geographic areas that are not
part of the designated nonattainment area. Through this theory, the
commenters suggested that the EPA could authorize states to meet the
RFP requirement based on reductions from the ``total area'' affecting
that nonattainment area, rather than from the actual designated
nonattainment area. As an alternative theory, the commenter argued that
the EPA could regulatorily redefine the emissions inventory requirement
of section 172(c)(3). To support this theory, the commenter disagreed
with the EPA's position that because the base year inventory required
by section 172(c)(3) includes the emissions from sources within the
designated nonattainment area, it supports the EPA's reading of the
statute with respect to the RFP requirement. The commenter instead
argued that because the emissions information used for modeling purpose
includes emissions from a much broader region (not just within the
nonattainment area or even just within the state), the EPA was wrong to
say in the proposal that the base year inventory for sources in the
area is the ``foundation for the attainment plan.'' Finally, the
commenter argued more broadly for the EPA to alter its interpretation
of the statutory language to allow for the commenter's preferred
approach to RFP. In support of their preferred approach to the RFP
requirement, the commenters noted that the EPA acknowledged in the
proposal that ``a literal interpretation is illogical'' for other
statutory requirements. To support this contention, the commenters
point to the criteria in section 188(d) that provide the criteria for
an extension of the Moderate area attainment date that require
significant interpretation in order to make them appropriate for the
statistical form of the current PM2.5 NAAQS rather than for
the exceedance-based form of the PM10 NAAQS that existed
when the CAA was amended in 1990.
    Response: The final rule requires that states demonstrate that they
meet the RFP requirement through emissions reductions from sources in
the nonattainment area. The EPA has decided to adopt this approach for
two reasons. First, it is the most consistent with the statute. It
aligns with RFP as defined in CAA section 171(1) and as required in CAA
section 172(c)(2) and 189(c), and is also most consistent with other
related requirements for attainment plans, such as the requirements for
imposition of emission controls, e.g., RACM and RACT, and with the
process for designations of nonattainment areas pursuant to section
107(d). Second, this approach is more straightforward to administer
because it retains a nonattainment area focus to the RFP requirement
and, while the alternative approaches would require complex and
potentially burdensome requirements to define the scope of the out-of-
area sources that must be inventoried and accounted for in the
determination of what constitutes RFP. The EPA has concluded that such
emissions reductions from sources outside the nonattainment area are
more properly accounted for and reflected in other elements of the
attainment plan, such as the attainment demonstration

modeling which will take into account the emissions reductions that
occur outside the nonattainment area in a less burdensome fashion.
    The EPA does not agree with the statutory interpretation of the RFP
requirement preferred by the commenters who suggested that the EPA
allow credit for emissions reductions from outside the area. Pursuant
to section 171(1), the statute defines the term ``reasonable further
progress'' to mean ``such annual incremental reductions in emissions .
. . as are required by this part or may reasonably be required by the
Administrator for the purposes of ensuring attainment of the applicable
[NAAQS] by the applicable date.'' This provision plainly provides EPA
with discretion to interpret this term within certain statutory
parameters, i.e., ``as are required by this part,'' and consistent with
the EPA's determination of what will be the appropriate approach for
timely attainment, i.e., ``for the purpose of ensuring attainment . . .
by the applicable date.'' Thus, for example, the EPA has authority to
interpret the RFP requirement to allow states to demonstrate generally
linear reductions or stepwise reductions, rather than as a specific
percentage of emissions reductions each year, as appropriate methods
for meeting the RFP requirement for purposes of the subpart 1 and
subpart 4 provisions applicable to the PM2.5 NAAQS. It does
not follow, however, that EPA is obligated to interpret the term
``reasonable further progress'' in other ways that the EPA considers
inconsistent with other relevant statutory requirements for attainment
plans or more broadly.
    To the contrary, the EPA believes that interpretation of the RFP
requirement to reflect reductions in emissions ``as are required by
this part,'' properly includes consideration of the context and
structure of the statute with respect to the other attainment plan
requirements. As explained in the proposal for this action, the EPA has
concluded that several other related requirements for attainment plans
support an interpretation of the RFP requirement for purposes of
PM2.5 to be limited to emissions reductions from sources
located within the nonattainment area. These requirements include the
emissions inventory requirement of section 172(c)(3), the RACM/RACT
requirement of section 172(c)(1) and section 189(a)(1)(C), and the not
less than 5 percent emission reduction requirement of section 189(d).
    With respect to the inventory requirement of section 172(c)(3), the
EPA explained in the proposal its view that because the emissions
inventory requirement explicitly refers to a comprehensive, accurate,
and current emissions inventory of emissions ``from all sources of the
relevant pollutant or pollutants in such area,'' this statutory
language supports the view that the primary focus of the attainment
plan is reductions of emissions from the nonattainment area, not
emissions reductions from sources elsewhere. Similarly, EPA explained
in the proposal its views that the court's decision in NRDC v. EPA, 571
F.3d 1245 (D.C. Cir. 2009) supports an interpretation of the RFP
requirement to apply to emissions reductions from sources within the
area. Although that decision focused on the RACT requirement for ozone
in particular, the reasoning of the court's decision based upon the
phrase ``in the area'' is consistent with the EPA's longstanding
approach to both RACM and RACT (or BACM and BACT for serious areas)
being required for emissions sources within the nonattainment area.
Given that states typically elect to demonstrate that they meet the RFP
requirement through emissions reductions that result from expeditious
imposition of RACM/RACT or BACM/BACT emission controls applied to
sources within the area, it is logical that the separate RFP
requirement should likewise be based upon the expeditious progress
towards attainment achieved through those emission controls. The EPA
emphasizes that the RFP requirement and the requirements of section
172(c)(6) are separate components of an attainment plan. In those
unusual circumstances where a state needs to impose specific additional
controls on sources outside the nonattainment area in accordance with
section 172(c)(6) to reach attainment, the state is not required to
alter the base year emissions inventory for sources within the area or
to alter its RFP analysis. As with other emissions reductions from
sources outside the area that the state may rely upon, emissions
reductions from measures states may impose to meet section 172(c)(6)
will be reflected in the modeled attainment demonstration and thus
included and taken into account in that fashion. [See sections IV.D.1
and VI.D.2 of the preamble for additional discussion of section
172(c)(6).]
    The EPA also considers this interpretation of the RFP requirement
to be consistent with the comparable requirements of CAA section
189(d). Specifically, section 189(d) requires that states with
nonattainment areas that fail to attain by the applicable attainment
date must make a new attainment plan submission in order to achieve
emissions reductions of not less than 5 percent of the most recent
emissions inventory ``for such area.'' As discussed in Section VII.F of
this rule, the EPA interprets the statute to require an area subject to
section 189(d) to achieve not less than a 5 percent reduction of the
most recent emissions inventory of direct PM2.5 or any
PM2.5 plan precursor ``for such area'' (meaning from sources
located within the nonattainment area). As a result, the EPA's
interpretation of ``in such area'' and ``for such area'' are
consistently applied for these related provisions of the CAA.
    As explained in the proposal, the EPA also sees no appropriate
legal or policy basis for addressing the geographic area from which
emissions reductions for RFP must be achieved for PM2.5
differently than is required by CAA section 182 for ozone. Both
pollutants typically result from emissions from numerous sources that
mix in the atmosphere and can transport great distances. For both
pollutants, the CAA provides different tools for states and the EPA to
address both the regional and the local contributions to violations of
the NAAQS in a given area. With respect to the local contribution, the
CAA provides a specific set of requirements (including RFP) designed to
assure that states are properly addressing the emissions from sources
located within the nonattainment area, whereas other requirements of
the CAA are designed to address contributions from greater distances,
whether from within the state, from other states, or even
internationally. Were EPA to interpret the RFP requirements to
authorize states to meet the emissions reductions requirement from
sources outside the area, this would be inconsistent with the
requirements specifically designed to assure that states get necessary
reductions from the local sources that contribute to the violations
through the attainment plan.
    One commenter recommended a potential statutory interpretation in
support of an outside-the-area approach. The EPA appreciates the
suggestion, but has determined that it would be too inconsistent with
the structure and purpose of the attainment plan requirements of the
statute. The commenter specifically suggested that EPA should redefine
the term ``area'' to encompass not just the designated nonattainment
area, but also some larger geographic area with sources of emissions
that cause or contribute to the ambient air quality; and that
reductions from such sources should be allowed to count towards meeting
the RFP requirement in addition to reductions

from sources in the designated nonattainment area. The EPA considers
such an approach inappropriate for several reasons. First, such a
reading would be inconsistent with the EPA's longstanding reading of
this same term in many important places throughout the statute,
including but not limited to explicit statutory references to the
``area'' in section 107(d)(1) (relevant to designations), section
107(d)(3) (relevant to redesignations), section 110(a)(2)(I) (relevant
to the scope of all of the attainment plan requirements imposed by Part
D), section 189(B)(2) (relevant to the schedule for submission of
attainment plans under subpart 4), and section 189(e) (relevant to the
statutory test for regulating precursors in a given ``area''). Creating
a different and conflicting definition of the word ``area'' for RFP
purposes is not appropriate for common sense reasons, and it would
require that the same word to be interpreted in multiple ways. Second,
the EPA considers the redefinition of the term ``area'' inappropriate
because it could be perceived as an attempt to alter the meaning of the
term as the D.C. Circuit has already interpreted it in the NRDC v. EPA
decision concerning the plain meaning of the term ``in the area.''
Third, to the extent that there are situations in which the boundaries
of the nonattainment area are incorrect because they fail to include
the sources that contribute violations in an adjacent area to the
extreme degree posited by the commenters, the statute already provides
a straightforward solution to such a situation through the initial
designation and redesignation provisions of section 107(d).
    Finally, the EPA acknowledges that in the prior 2007
PM2.5 implementation rule, the EPA did adopt a different
interpretation of the RFP requirement for the first time that would
have authorized states to meet the RFP requirement with emissions
reductions from sources outside the nonattainment area within certain
narrow parameters for purposes of the 1997 PM2.5 NAAQS.\127\
The EPA received a petition for reconsideration on this specific issue
and granted the petition to reexamine that aspect of the 2007
PM2.5 implementation rule.\128\ Before the EPA proceeded
with that reconsideration, however, the litigation over the 2007
PM2.5 implementation rule and the 2008 NSR revisions
(addressing the PM2.5 NAAQS) proceeded with challenges on
other statutory authority issues while the petition for reconsideration
was still under evaluation. This litigation resulted in the court's
decision in NRDC v. EPA, 706 F.3d 428 (D.C. Cir. 2013). In that
decision, the court remanded the entire 2007 PM2.5
implementation rule, including the portions relevant to the RFP
requirement, to the EPA for failure to comply with the statutory
requirements of subpart 4. This rulemaking constitutes the EPA's
response to that judicial remand and through this process the EPA is
replacing the 2007 PM2.5 implementation rule, including the
prior regulatory provisions and guidance related to states meeting the
RFP requirements with emissions reductions from outside the designated
nonattainment area. Accordingly, upon completion of this rulemaking the
EPA will be interpreting the RFP requirement consistent with past
practice. The EPA also notes, as a factual matter, that states have not
been using this feature of the 2007 PM2.5 implementation
rule.\129\ Aside from the lack of a legal basis for the commenter's
preferred approach to RFP, thus far the EPA's interpretation of the
requirements has not posed the practical difficulties that the
commenter raised.
---------------------------------------------------------------------------

    \127\ See the discussion of this prior approach to RFP in the
proposal for this action. 80 FR 15388-89. By its terms, the 2007
PM2.5 Implementation Rule applied only to the 1997
PM2.5 NAAQS. The EPA's guidance for the 2006
PM2.5 NAAQS did not follow this approach with respect to
the RFP requirement for purposes of the 2006 PM2.5 NAAQS.
The EPA later withdrew the guidance for the 2006 PM2.5
NAAQS as a result of the court decision in NRDC v. EPA, 706 F.3d 428
(D.C. Cir. 2013).
    \128\ See, Letter to David S. Baron, EarthJustice, from Gina
McCarthy, Assistant Administrator, dated May 13, 2010. A copy of
this letter is in the docket for this action.
    \129\ See, e.g., ``Approval and Promulgation of Implementation
Plans; California; 2007 South Coast PM2.5 Plan and 2007
State Strategy; Proposed Rule,'' 76 FR 41567, 41577-78 (July 14,
2011); Final Approval of Air Quality Implementation Plans;
California; South Coast Attainment Plan for the 1997
PM2.5 NAAQS Standards; Final Rule,'' 76 FR 69928
(November 9, 2011).
---------------------------------------------------------------------------

5. Other RFP Considerations
    a. Summary of Proposal. The proposal outlined the statutory
requirements and existing guidance for RFP. During this discussion, the
following guidance from the Addendum was referenced, ``Additionally,
the EPA believes that it is appropriate to require early implementation
of the most cost-effective control measures . . . while phasing in the
more expensive control measures.'' \130\ The proposal also discussed
other RFP considerations, including PM2.5 nonattainment
areas that are shared by more than one state or tribe.
---------------------------------------------------------------------------

    \130\ Ibid. at 42016.
---------------------------------------------------------------------------

    b. Final Rule. The EPA is finalizing that, although early
implementation of the most cost-effective control measures is often
appropriate, states should consider both cost-effectiveness and
pollution reduction effectiveness when developing implementation
schedules for their control measures and may implement measures that
are more effective at reducing PM2.5 earlier to provide
greater public health benefits. This increased flexibility enables
states to develop a more effective implementation schedules for their
control measures while efficiently using their resources.
    For a multi-state or multi-jurisdictional nonattainment area, the
RFP plans for each state represented in the nonattainment area shall
demonstrate RFP on the basis of common multi-state inventories. The
states or jurisdictions within which the area is located must provide a
coordinated RFP plan. Each state must ensure that the sources within
its boundaries comply with enforceable emission levels and other
requirements that in combination with the reductions planned in other
states within the nonattainment area will provide for attainment as
expeditiously as practicable and demonstrate RFP consistent with these
regulations. In general, the EPA seeks to ensure that PM2.5
nonattainment areas that are shared by more than one state or tribe
meet RFP requirements as a whole. States and tribes that share a
nonattainment area should therefore consult with one another to develop
the RFP analysis and control strategy implementation schedule for the
area as a whole. Such states and tribes should work with the EPA region
or regions that oversee them to confirm that their collective approach
is appropriate for RFP.
    The EPA's approach for states to meet the RFP requirement is
designed to ensure emissions reductions will yield incremental
improvements in air quality on the path to attainment, while being
sufficiently flexible to accommodate the range of control strategies
necessary to address the complex mixtures of pollutants comprising
PM2.5 in different areas.
    c. Comments and Responses. Comment: Some commenters asserted that
the EPA should not ``require'' implementing the most cost-effective
measures first since states should have the flexibility to implement
the more effective but less cost-effective measure earlier, thus
providing earlier and greater public health benefits.
    Response: In this final rule, the EPA is providing states with the
flexibility to

implement measures that are more effective at reducing PM2.5
earlier to provide greater public health benefits, but is not requiring
it. This increased flexibility is in keeping with the overall
requirement of expeditious attainment of the NAAQS.

G. Quantitative Milestones

1. General Approach to Quantitative Milestones
    a. Summary of the Proposal. The proposal built from the statutory
language of 189(c)(1), which requires quantitative milestones that (1)
demonstrate RFP, and (2) must be achieved every 3 years until the area
is redesignated attainment. The proposal first addressed the issue of
the starting date for counting the 3-year periods. For a Moderate area
that cannot practicably attain the relevant PM2.5 NAAQS
within the statutory timeframe for a Moderate area, the EPA proposed
that a state must submit two sets of quantitative milestones--the first
set to be achieved at year 4.5 from designation and the second set to
be achieved at year 7.5 from designation. The EPA also proposed that
the quantitative milestones contained in the attainment plan for a
Moderate nonattainment area must be constructed such that they can be
tracked, quantified and/or measured adequately in order for the state
to meet its milestone reporting obligations, which come due 90 days
after a given milestone date. The EPA therefore proposed to require
that states select the quantitative milestones that are appropriate and
quantifiable and that will provide for objective evaluation of progress
toward attainment in their Moderate PM2.5 nonattainment
area, whether the area can practicably attain the PM2.5
NAAQS by the statutory attainment date or not. In addition to this
general proposed approach for selecting quantitative milestones for a
Moderate nonattainment area, the EPA proposed a requirement that, at a
minimum, states must include in all attainment plans for Moderate
PM2.5 nonattainment areas a metric to confirm that all
control measures identified and adopted as RACM and RACT for the area
have been fully implemented within 4 years of designation.
    b. Final Rule. Section 189(c) of the Act explicitly requires that
quantitative milestones must be achieved every 3 years, but does not
specify the starting date for counting the 3 year periods. In the
General Preamble and Addendum, the agency stated that quantitative
milestones must be achieved every 3 years starting from the due date
for the plan submission (i.e., because the Moderate area attainment
plan is due no later than 18 months after designation of the area, the
first set of milestones would need to be achieved 4.5 years after the
area's designation) until the area is redesignated attainment.\131\ The
EPA is finalizing this approach for the PM2.5 NAAQS. The EPA
interprets this requirement to be the most appropriate reading of CAA
section 189(c)(1) which requires ``quantitative milestones which are to
be achieved every 3 years until the area is redesignated attainment.''
This approach is also consistent with the longstanding approach
outlined in the General Preamble.\132\ These timeframes for the
quantitative milestones apply to all areas designated nonattainment for
a PM2.5 NAAQS on or after January 15, 2015, including all
areas designated nonattainment effective April 15, 2015 for the 2012
PM2.5 NAAQS.\133\ See 40 CFR 51.1013(a).
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    \131\ General Preamble, 57 FR 13498 (April 16, 1992), at page
13539.
    \132\ 57 FR 13539.
    \133\ 80 FR 2206, January 15, 2015.
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    For all areas designated nonattainment for the 1997 and/or 2006
PM2.5 NAAQS before January 15, 2015,\134\ the EPA is
establishing December 31, 2014 as the starting point for the first 3
year period for quantitative milestones under CAA section 189(c). This
is because December 31, 2014, was the due date for states to submit
additional SIP elements necessary to satisfy the subpart 4 Moderate
area requirements for the 1997 and 2006 PM2.5
standards.\135\ Establishing December 31, 2014 as the starting point
for the first 3 year period under CAA section 189(c) for the 1997 and
2006 PM2.5 standards is in keeping with the EPA's historical
approach to quantitative milestone dates (i.e., using the due date for
the Moderate area plan submission as the starting point for the first 3
year milestone period). Thus, for any area designated nonattainment for
the 1997 and/or 2006 PM2.5 NAAQS that has not yet attained
these NAAQS and therefore continues to have attainment planning
obligations for these NAAQS, the state must submit quantitative
milestones to be achieved by December 31, 2017 (the first milestone
date), at minimum. Additional milestone dates may also apply to such an
area depending on the relevant attainment planning period. See 40 CFR
51.1013(a)(4).
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    \134\ The EPA promulgated nonattainment area designations for
the 1997 PM2.5 NAAQS effective April 2005 (70 FR 944,
January 5, 2005 and 70 FR 19844, April 14, 2005). The EPA
promulgated nonattainment area designations for the 2006
PM2.5 NAAQS effective December 2009 (74 FR 58688,
November 13, 2009), March 2011 (76 FR 6056, February 3, 2011), and
November 2012 (77 FR 65310, October 26, 2012).
    \135\ 79 FR 31566 (June 2, 2014) (final rule establishing
subpart 4 moderate area classifications and deadline for related SIP
submissions) (``Classification and Deadline Rule''). Although the
Classification and Deadline Rule did not affect any action that the
EPA had previously taken under CAA section 110(k) on a SIP for a
PM2.5 nonattainment area, the EPA noted that states may
need to submit additional SIP elements to fully satisfy the
applicable requirements of subpart 4, even for areas with previously
approved PM2.5 attainment plans, and that the deadline
for any such additional plan submissions was December 31, 2014. Id.
at 31569.
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    Regardless of whether or not an attainment plan demonstrates
attainment by the statutory attainment date, the EPA requires that all
Moderate area PM2.5 attainment plans must define appropriate
quantitative milestones to be achieved by 4.5 years and 7.5 years
following designation of the area. Although it occurs after the
Moderate area attainment date, the EPA is requiring Moderate area plans
to contain this 7.5 year milestone, even where those plans demonstrate
attainment before the milestone would arrive. Where the EPA uses its
discretionary authority in CAA section 188(b)(1) to reclassify an area
before the Moderate area attainment date applicable to the area, CAA
section 189(b)(2) allows the state up to 4 years to submit the required
Serious area attainment demonstration and related plan elements, such
as quantitative milestones. For example, if the reclassification occurs
4 years after designation, the state may be allowed to submit the
Serious area quantitative milestones up to 8 years after designation,
well after the second milestone date (7.5 years after designation) has
passed. Without the 7.5 year milestone requirement, this circumstance
would undermine the purpose of the quantitative milestone requirement,
which is to ensure that states will report to EPA on each nonattainment
area's progress toward attainment at regular intervals, even following
reclassification.\136\
---------------------------------------------------------------------------

    \136\ See, e.g., Addendum at 42016, n. 43 (noting that the plain
terms of CAA section 189(c) require that milestones be achieved
every 3 years until the area is redesignated attainment and,
therefore, do not contemplate any breaks in the milestones due to an
area's reclassification).
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    A similar issue would result in the event that a Moderate area that
did demonstrate attainment in the original attainment plan fails to
attain by the statutory attainment date. In this case, the area would
have failed to meet the attainment date which is as expeditiously as
practicable but no later than the end of the sixth calendar year after
designation as required by CAA section 188(c)(1). Section 188(b)(2) of
the Act allows the Administrator up to

6 months to determine that a Moderate failed to attain and reclassify
that area to Serious, which would be at least 6.5 years after
designation. As described in Section VI.A.1 of this preamble, the
Serious area would have 18 months from reclassification due to a
failure to attain (8 years after designation) in order to submit an
attainment plan. The EPA has therefore determined that, in order to
avoid gaps of greater than 3 years in the implementation of
quantitative milestones, all Moderate area attainment plans must
contain quantitative milestones to be achieved 4.5 years and 7.5 years
after designation and which demonstrate continued progress toward
timely attainment of the relevant PM2.5 NAAQS. In the event
that the area fails to attain, this will provide the EPA with
appropriate tools necessary to continue to monitor the area's continued
progress toward attainment while the state develops the Serious area
attainment plan.
    The quantitative milestones contained in the attainment plan for a
Moderate nonattainment area should be constructed such that they can be
tracked, quantified and/or measured adequately in order for the state
to meet its milestone reporting obligations, which come due 90 days
after a given milestone date. In the Addendum, the EPA suggested some
possible metrics that ``support and demonstrate how the overall
quantitative milestones identified for an area may be met,'' such as
percent implementation of control strategies, percent compliance with
implemented control measures, and adherence to a compliance schedule.
This list was not exclusive or exhaustive but reflected the EPA's view
that the purpose of the quantitative milestone requirement is to
provide an objective way to determine whether the area is making the
necessary progress towards attainment by the applicable attainment
date.\137\ The EPA interprets Section 189(c) of the Act to allow states
to identify milestones that are suitable for the specific facts and
circumstances of the attainment plan for a particular area, so long as
they provide an objective means to measure RFP.
---------------------------------------------------------------------------

    \137\ Addendum to the General Preamble, 59 FR 41998 (August 16,
1994), at page 42016.
---------------------------------------------------------------------------

    This rule requires that each attainment plan for a Moderate
PM2.5 nonattainment area contain quantitative milestones
that provide for objective evaluation of RFP toward attainment in the
PM2.5 nonattainment area, whether the plan provides for
attainment of the PM2.5 NAAQS by the statutory attainment
date or demonstrates that attainment by such date is impracticable. For
this approach, the EPA does not require that such quantitative
milestones take any particular form, merely that they provide a means
to evaluate progress (i.e., demonstrate RFP) meaningfully. The EPA will
review each attainment plan submission on a case-by-case basis to
determine whether the quantitative milestones contained in the plan are
specific enough to provide an objective means for evaluating the area's
progress toward attainment, consistent with the statutory requirements
of CAA section 189(c). The EPA recommends that states confer with their
respective EPA regional office to develop appropriate quantitative
milestones. See 40 CFR 51.1013(a).
    The Addendum stated that the Moderate area quantitative milestones
``will be met by showing that emissions reductions scheduled to be made
between the SIP due date and the attainment date for these moderate
areas were actually achieved. Most of these emissions reductions will
result from implementation of RACM (including RACT) as part of the
moderate area SIP.'' However, this rule does not specify that
quantitative milestones must be expressed in terms of emissions
reductions. The EPA recognizes that it is impractical to expect that a
state will always be able to quantify and compare real and projected
emissions reductions, and submit a report to the EPA within 90 days of
a given milestone as required under CAA section 189(c)(2). Therefore,
the final rule requires that, at a minimum, states must include in all
attainment plans for Moderate PM2.5 nonattainment areas a
milestone that all control measures identified and adopted as RACM and
RACT for the area have been fully implemented within 4 years of
designation. This milestone specifically derives from section
189(a)(1)(C) of the Act, that applies to all Moderate areas and thus
represents a milestone that all Moderate areas must meet regardless of
whether it is listed explicitly as an individual milestone. See 40 CFR
51.1013(a)(1)(iii).
    For an area that submitted air quality targets with the RFP plan
under the optional provision that was described in Section IV.F of this
preamble, an air quality based milestone (i.e., one that is expressed
in terms of an ambient PM2.5 level) is strongly recommended
to be included in order to confirm that the air quality target has been
met for the quantitative milestone year. If used, this milestone will
be compared to the most recently certified monitored ambient air data
as part of the milestone report due after the area reaches each
quantitative milestone date. The EPA recognizes that certified
monitored ambient air data are not available for some period after a
calendar year ends. As a result, the EPA expects that this quantitative
milestone may sometimes be satisfied with data that are over a year
old. For example, for Moderate areas having an effective date of
designations in April 2015, the first quantitative milestone date will
be in October 2019 (3 years after the 18 month SIP due date), and the
associated report will be due 90 days later, in January 2020. In this
example, the state would likely have to rely upon certified air quality
data for 2018 because data for the 2019 calendar year would not yet be
fully certified. Additionally, this milestone should normally be
reported in the same form as the applicable PM2.5 NAAQS.
However, the EPA expects that in some circumstances, it may be
appropriate to use annual averages instead of the 3 year average to
help justify variations due to meteorological occurrences.
    c. Comments and Responses. Comment: Some commenters stated the Act
may be read to conclude that the requirement to include any
quantitative milestones in a Moderate area plan does not apply to a
plan demonstrating the impracticability of attaining the NAAQS by the
attainment date.
    Response: The EPA's longstanding interpretation of CAA section
189(c) as a requirement that applies to all PM10
nonattainment area plans, including those demonstrating that attainment
by the applicable attainment date is impracticable, is consistent with
the purpose and structure of subpart 4. The design of the CAA for PM
nonattainment areas combines the requirements of subpart 1 and subpart
4 to support expeditious attainment of the applicable NAAQS. RFP is the
prescribed tool available to a state to plan their emission reduction
progress toward expeditious attainment. Quantitative milestones are a
critical aspect of the CAA and the attainment plan in order for the EPA
to monitor the area's RFP toward expeditious attainment and trigger the
appropriate response if RFP is not maintained. The EPA thus determined
that allowing an area to simply not submit any quantitative milestones
would not afford the EPA the necessary tools to monitor RFP toward
expeditious attainment.
2. Milestone Report Submission
    a. Summary of the Proposal. Because the statute does not define the
parameters of quantitative milestone demonstrations, the EPA has
discretion to determine the components of the required demonstration
and the form

and manner for submission. The proposal took comment on options for
doing this. The EPA proposed to require that the milestone report
submission must include the following four components: (i) A
certification by the Governor or Governor's designee that the state's
attainment plan control strategy is being implemented as described in
the applicable attainment plan, (ii) technical support sufficient to
document completion statistics for appropriate milestones and to
demonstrate that the quantitative milestones have been satisfied and
how the emissions reductions achieved to date compare to those required
or scheduled to meet RFP, (iii) as applicable, an air quality screening
analysis to determine if measured air quality progress is consistent
with the expected air quality improvement target correlated with the
RFP emissions reductions for the previous 3 year period, and (iv) an
evaluation of whether the PM2.5 NAAQS will be attained by
the projected attainment date for the area. In addition, the EPA
proposed that the milestone report must include a description and
schedule for any remedial actions the state has taken or will take to
address any failure to meet a quantitative milestone, including the
implementation status of contingency measures for failing to meet RFP
in the area.
    The EPA also sought comment on how electronic reporting could
facilitate a state's submission of the required milestone report, how
it could accommodate the various narrative and data-dependent
components that the EPA proposed be part of such a submission, and what
particular system features might be desirable to accommodate milestone
report submissions through the eSIP system.
    b. Final Rule. The final rule, mirroring section 189(c)(2) of the
Act, requires that each state containing a PM2.5
nonattainment area submit to EPA, within 90 days after each milestone
date applicable to the area, a demonstration that all measures in the
approved plan (including the RFP plan) for the area have been
implemented and that the milestone has been met. This rule outlines the
content required by the EPA for the quantitative milestone report. The
EPA must then determine whether or not a state's demonstration is
adequate within 90 days after receiving a demonstration which contains
the required information and analysis. The EPA intends to promptly
inform the relevant state of any determination that the state has
failed to submit a timely quantitative milestone report and any
determination that a submitted milestone report is not adequate.
    The EPA will work with a state to assist them in meeting the
reporting deadline, and expects that, because the report is to be
fairly low burden and may be submitted electronically through eSIP, in
most cases the state will submit it on time, especially if they have
implemented the programs required to meet their milestones. If,
however, a state fails to submit a milestone demonstration report by
the due date or the EPA determines that a milestone was not met, the
final rule requires the state to submit a SIP revision within 9 months
of either the missed reporting deadline or the EPA's determination of
the state's failure to meet a milestone. According to the statutory
requirements of CAA section 189(c)(3), the new SIP revision must assure
``that the State will achieve the next milestone (or attain the
national ambient air quality standard . . . , if there is no next
milestone) by the applicable date.'' If a state fails to make a SIP
submission to correct a failure to meet RFP expeditiously, sanctions
under CAA sections 110(m) and 179(b) may apply. If a state is unable to
correct a failure to meet RFP, this may be evidence that the state
cannot practicably attain the NAAQS by the applicable attainment date
and may serve as a basis for reclassification of the area to Serious
under CAA section 188(b)(1).
    As previously noted, the EPA has offered guidance about what the
milestone report should contain. The Addendum says, ``This report must
contain technical support sufficient to document completion statistics
for appropriate milestones. For example, the demonstration should
graphically display RFP over the course of the relevant 3 years and
indicate how the emissions reductions achieved to date compare to those
required or scheduled to meet RFP and the required [quantitative]
milestones. The calculations (and any assumptions made) necessary to
determine the emissions reductions to date should also be submitted.
The demonstration should also contain an evaluation of whether the
PM10 NAAQS will be attained by the projected attainment
date.'' \138\ This guidance is still appropriate for states
demonstrating compliance with RFP and quantitative milestones for
PM2.5 NAAQS. The EPA requires that the milestone report
submission must include the following components. See 40 CFR
51.1013(b).
---------------------------------------------------------------------------

    \138\ Ibid. at 42017.
---------------------------------------------------------------------------

    First, the report must include a certification by the Governor or
Governor's designee that the SIP control strategy is being implemented
consistent with the RFP plan, as described in the applicable attainment
plan. Second, the report must contain technical support, including
calculations, sufficient to document completion statistics for each
quantitative milestone and to demonstrate that the quantitative
milestones have been satisfied and how the emissions reductions
achieved to date compare to those required or scheduled to meet RFP.
Additionally, the report must include a discussion of whether the
PM2.5 NAAQS will be attained by the projected attainment
date for the area. See 40 CFR 51.1013(b). The EPA decided not to
finalize the proposed requirements to include an air quality screening
analysis or the description and schedule for remedial actions taken by
the state to address a failure to meet a quantitative milestone. This
decision was made because the remaining components of the quantitative
milestone report are sufficient to enable the EPA to assess whether the
nonattainment area is meeting RFP.
    As stated in the Addendum, the milestone report must be submitted
from the Governor or Governor's designee to the Regional Administrator
of the respective EPA Regional Office serving the submitting state. The
EPA will notify the state of its determination (regarding whether or
not the state's report is adequate) by sending a letter to the
appropriate Governor or Governor's designee. The EPA encourages states
to submit milestone reports, including supporting documents, through
the agency's electronic SIP (eSIP) submission system in order to
simplify the process and reduce resource burden on all sides.
    c. Comments and Responses. Comment: Some commenters did not support
the proposal and stated that requiring this level of documentation is
unnecessary and puts an excessive workload burden on states and local
agencies.
    Response: The EPA recognizes that there is some level of resources
required to address the requirements prescribed by every rule. However,
the EPA concluded that the benefit offered to the public by reviewing
quantitative milestone reports while assessing whether nonattainment
areas are making reasonable further progress toward attaining the
PM2.5 NAAQS and the associated public health benefits
outweigh the anticipated workload burden for states.
    Comment: Some commenters stated that the first two components of
the

quantitative milestone report described in the proposal are sufficient
to comply with the requirements of CAA section 189(c)(2). The
commenters stated that the proposed air quality screening analysis is
not supported by the statute and is unnecessary if the second component
is fulfilled. The commenters stated that the proposed description and
schedule for remedial actions the state has taken or will take to
address any failure to meet a quantitative milestone is more than what
is necessary to demonstrate compliance with RFP milestones and could
require revisions to the SIP.
    Response: After considering these comments and in an effort to
simplify the rule, the EPA decided to eliminate the two proposed
requirements for the quantitative milestone report as suggested by
these commenters. As stated earlier, this decision was made because the
EPA determined that the remaining components of the quantitative
milestone report are sufficient to enable the EPA to assess whether the
nonattainment area is meeting RFP.
    Comment: One commenter stated that, while they would not object to
filing periodic reports, as part of their milestone report, the EPA
should not insist on the state actually inspecting all covered
facilities and indicating that RACT or RACM has not been implemented if
a small subset of facilities is found in violation.
    Response: It is not the intent of the EPA to require states to
physically inspect all covered sources to verify the implementation of
required control measures. The intent is that, at the time of the
milestone due date, all covered sources would be legally required to
have implemented required control measures and the state has reasonably
been assured that this occurred.

H. Contingency Measures

1. Summary of the Proposal
    The Act requires Moderate PM2.5 nonattainment area plans
to contain contingency measures consistent with CAA section 172(c)(9).
Contingency measures are additional control measures to be implemented
in the event that the EPA determines that an area failed to meet RFP
requirements (including associated quantitative milestones) or failed
to attain the PM2.5 primary standard by the applicable
attainment date. These measures must be fully adopted rules or control
measures that are ready to be implemented quickly upon failure to meet
RFP or failure of the area to meet the standard by its attainment date,
and such measures are required to take effect without further action by
the state or the EPA. The EPA proposed and sought comment on general
requirements for contingency measures for Moderate PM2.5
nonattainment areas. The EPA has longstanding interpretations of the
statute with respect to the contingency measure requirement, both for
PM and for other pollutants, in the General Preamble and Addendum.
These documents provide guidance and recommendations for states to
follow in submitting contingency measures, and the proposal did not
contain any significant changes to the existing guidance and
recommendations. However, the EPA sought comment on whether the
guidance needed to be revised or expanded. Additionally, as discussed
in the proposal, the EPA believes that the DC Circuit's decision in
NRDC v. EPA does not affect the overall contingency measure
requirements that were finalized in the remanded 2007 PM2.5
Implementation Rule. The EPA determined this because CAA section
172(c)(9) imposes the contingency measure requirement for attainment
plans for the PM2.5 NAAQS and it is not superseded or
subsumed by any specific contingency measure requirements under subpart
4. As a result, the proposal for this rule remained very similar to the
final 2007 PM2.5 Implementation Rule.
2. Final Rule
    Consistent with the proposal, the final rule codifies existing
policies on contingency measures, but does not make significant changes
to these policies. Although CAA section 172(c)(9) requires contingency
measures, the provision does not specify exactly what parameters such
measures must meet. The EPA is finalizing an approach to contingency
measures for the PM2.5 NAAQS that is similar to the approach
recommended in earlier EPA guidance. Specifically, in order for
contingency measures to be approvable as part of a state's Moderate
area attainment plan submission for the PM2.5 NAAQS, the
state plan must meet the following general requirements (See 40 CFR
51.1014):
    (1) Contingency measures must be fully adopted rules or control
measures that are ready to be implemented quickly upon a determination
by the Administrator of the nonattainment area's failure to meet RFP,
failure to meet any quantitative milestone, failure to submit a
quantitative milestone report or failure to attain the standard by the
applicable attainment date.
    (2) The state's attainment plan submission must contain trigger
mechanisms for the contingency measures, specify a schedule for
implementation, and indicate that the measures will be implemented with
minimal further action by the state or by the EPA.
    (3) The contingency measures shall consist of control measures that
are not otherwise included in the control strategy or that achieve
emissions reductions not otherwise relied upon in the control strategy
for the area.
    (4) Contingency measures should provide for emissions reductions
approximately equivalent to 1 year's worth of reductions needed for
RFP, based on the overall level of reductions needed to demonstrate
attainment divided by the number of years from the base year to the
attainment year, or approximately equivalent to 1 year's worth of air
quality improvement or emissions reductions proportional to the overall
amount of air quality improvement or emissions reductions to be
achieved by the area's attainment plan.
    Regarding the first two points, consistent with prior guidance,
states must show that their contingency measures can be implemented
with minimal further action on their part and with no additional
rulemaking actions such as public hearings or legislative review. After
the EPA determines that a moderate PM2.5 nonattainment area
has failed to meet an RFP requirement or to attain the PM2.5
NAAQS, the EPA generally expects all actions needed to effect full
implementation of the contingency measures to occur within 60 days
after the EPA notifies the state of the area's failure. The EPA intends
to notify the state of a failure to meet RFP or to attain the NAAQS by
publication of its determination in the Federal Register. The state
should ensure that the contingency measures are fully implemented as
expeditiously as practicable after such notice.\139\
---------------------------------------------------------------------------

    \139\ Ibid. at 42015.
---------------------------------------------------------------------------

    Regarding the third point, the EPA interprets the contingency
measure requirement of CAA section 172(c)(9) to require control
measures that are not otherwise included in the control strategy or
that achieve emissions reductions not otherwise relied upon in the
control strategy for the area. However, suitable contingency measures
may be measures that were technologically and economically feasible for
the area, but did not qualify as RACM or RACT or additional reasonable
measures for one or more reasons. For example, a candidate contingency
measure may have been deemed technologically and

economically feasible, but it was not needed to achieve expeditious
attainment in a Moderate area for which the state could demonstrate
attainment by the statutory attainment date and therefore was not
included as part of the attainment demonstration for the area. It is
important that states make decisions concerning contingency measures in
conjunction with their determination of the overall control strategy
for bringing the area into expeditious attainment, and that states
first must identify those control measures needed in order to
demonstrate expeditious attainment of the standards; any remaining
measures should then be considered as candidates for contingency
measures.
    As discussed in Section IV.D of this preamble, the RACM/RACT
provisions in this rule require that, for Moderate areas that cannot
practicably attain the NAAQS by the statutory attainment date, states
must implement all control measures that they determine to be
reasonable (i.e., all technologically and economically feasible
measures) for sources in the area. In such cases, the contingency
measures for such nonattainment areas would necessarily exceed the
criteria for determining whether a measure is reasonable for purposes
of RACM/RACT and additional reasonable measures. For example,
contingency measures could consist of reasonable controls on sources
outside the nonattainment area, early implementation of BACM/BACT on
select sources inside the area, other measures identified by the state,
or a combination thereof, that collectively provide approximately
equivalent to 1 year's worth of emissions reductions/air quality
improvement. Such contingency measures would only be triggered in the
event the area fails to meet RFP; the EPA does not interpret the
requirement for contingency measures for failing to attain the NAAQS by
the applicable attainment date to apply to a Moderate area that a state
demonstrates cannot practicably attain the NAAQS by the statutory
attainment date. Rather, the EPA believes it is appropriate for the
state to identify and adopt these measures in a timely way as part of
the Serious area attainment plan that it will develop once the EPA
reclassifies such an area. However, if a Moderate area that cannot
practicably attain the NAAQS fails to meet RFP when reviewed as part of
the quantitative milestone either 4.5 or 7.5 years after designation,
the requirement to implement contingency measures would be triggered as
required by CAA section 172(c)(9). For any Moderate PM2.5
nonattainment area, contingency measures can include measures that
achieve emissions reductions on sources located outside the
nonattainment area as well as from sources within the nonattainment
area, provided that the measures offer reasonable assurance that the
appropriate air quality impact will result within the nonattainment
area.
    The final rule continues to allow states to rely on federal
measures (e.g. federal mobile source measures based on the incremental
turnover of the motor vehicle fleet each year) and local measures
already scheduled for implementation that provide emissions reductions
in excess of those needed to provide for RFP or expeditious attainment.
The key is that the statute requires that contingency measures provide
for additional emissions reductions that are not relied on for RFP or
attainment and that are not included in the RFP or attainment
demonstrations as meeting part or all of the contingency measure
requirements. The purpose is ``to provide a cushion while the plan is
being revised to meet the missed milestone.'' Nothing in the statute
precludes a State from implementing such measures before they are
triggered. Additionally, the EPA determined that the court ruling
upholding contingency measures that were previously required and
implemented where they were in excess of the attainment demonstration
and RFP for ozone attainment plans necessitates similar treatment for
PM2.5 NAAQS.\140\ The EPA has approved numerous SIPs under
this interpretation, i.e., SIPs that use as contingency measures one or
more federal or local measures that are in place and provide reductions
that are in excess of the reductions required by the attainment
demonstration or RFP plan.\141\
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    \140\ See LEAN v. EPA, 382 F.3d 575 (5th Cir., 2004).
    \141\ See, e.g., 62 FR 15844 (April 3, 1997); 62 FR 66279
(December 18, 1997); 66 FR 30811 (June 8, 2001); 66 FR 586 and 66 FR
634 (January 3, 2001); 78 FR 64402 (October 29, 2013).
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    For these reasons, the EPA concluded that this approach is
reasonable for Moderate PM2.5 nonattainment areas that can
demonstrate attainment by the statutory attainment date, as the state
would calculate the emissions reductions needed for RFP separately from
the control strategy determination for such an area. However, crediting
an area for ``excess'' emissions reductions to satisfy the contingency
measure requirement is not allowable for Moderate areas that cannot
practicably attain by the statutory attainment date. Under the EPA's
approach for calculating RFP for such areas, RFP would be calculated
directly from the projected emissions reductions from all control
measures identified for the area (as RACM and RACT or additional
reasonable measures), such that there should be no difference between
emissions reductions estimated from control measures and those
estimated for demonstrating RFP.
    Finally, consistent with the EPA's past approach for contingency
measures for PM2.5 nonattainment areas, the EPA expects that
the emissions reductions from contingency measures should be
approximately equivalent to 1 year's worth of emissions reductions
while the state is revising its attainment plan for the area. States
should explain the amount of anticipated emissions reductions to be
accomplished by the contingency measures outlined in the plan. In the
rare event that an area is unable to identify contingency measures to
account for approximately 1 year's worth of emissions reductions, the
state should provide a reasoned justification why the smaller amount of
emissions reductions is appropriate. As described in Section IV.F of
this preamble, the EPA requires an approach for interpreting the
statutory RFP requirement that would require demonstrating RFP based on
reductions from sources located inside the nonattainment area. Keeping
with the historic linkage between RFP and contingency measures, the EPA
is also finalizing a similar approach for calculating 1 year's worth of
emissions reductions for purposes of adopting appropriate contingency
measures. That is, the EPA's approach for determining the level of
emissions reductions for contingency measure purposes is to calculate
the annual reductions in emissions of direct PM2.5 and
PM2.5 plan precursors needed from sources located inside the
nonattainment area. As explained earlier, however, some or all of the
contingency measures reductions can come from outside the area if they
are demonstrated to produce the appropriate air quality impact within
the nonattainment area.
    This rule requires that states must implement contingency measures
after the EPA determines that the area has either failed to meet RFP
requirements, failed to meet any quantitative milestone, failed to
submit a quantitative milestone report, or failed to attain the
standards by the applicable attainment date. The purpose of the
contingency measure provision is to ensure that corrective measures are
put in place automatically at the time that the EPA makes its
determination that an area has either failed to meet RFP or failed to
meet the standard by its attainment date. The EPA is required to

determine within 90 days after receiving a state's quantitative
milestone demonstration, and within 6 months after the attainment date
for an area, whether these requirements have been met. The additional
consequences for states with areas that fail to attain the NAAQS or to
meet RFP are described in section 179(d) of the CAA and discussed in
Section V of this preamble.
    See Section IV.A of this preamble for a discussion of the due dates
for submission of contingency measures and other attainment plan
elements.
3. Comments and Responses
    Comment: Commenters stated that requiring contingency measures in
areas with mature air pollution control programs is very challenging
because they already have developed aggressive control measures to meet
CAA requirements and support expeditious attainment. Commenters
asserted that it would be extremely difficult to develop further
control measures to meet any contingency measure requirements.
Commenters objected to the proposed requirement that contingency
measures must be approximately equivalent to 1 year's worth of
emissions reductions because it is a departure from existing guidance
which states the contingency emissions reductions ``should be''
approximately equal and because sometimes identifying control measures
for this level of reductions is just not possible. Commenters advocated
that EPA should provide a more reasonable approach to the contingency
measure requirement, but did not provide specific recommendations.
Other commenters stated that contingency measures should provide 1
year's worth of emissions reductions needed for RFP.
    Response: The EPA acknowledges that states containing areas with
more longstanding and pervasive nonattainment problems may already have
implemented many control measures for purposes of attaining the NAAQS,
and there may be fewer sources and measures available to meet the
contingency measure requirements of the statute. However, the EPA notes
that section 172(c)(9) of the CAA explicitly requires states to adopt
contingency measures to apply in the event of failure to meet RFP or
failure to attain the NAAQS as a required component of all attainment
plans. Typically, contingency measures will be comprised of measures
that a state and the EPA have determined are not required to meet RACM/
RACT or other requirements, e.g., on the grounds that they are more
technologically or economically challenging. As a result, such measures
may not be required as RACM/RACT, but are nevertheless available for
use as contingency measures. Another approach to contingency measures,
if appropriate, would be to rely on control measures imposed on sources
outside the boundaries of the designated nonattainment area. Such
contingency measures require adequate support to establish that the
reductions would have the intended impacts within the nonattainment
area, but can be a source of additional measures for this purpose.
    Finally, the EPA notes that its longstanding guidance is that
contingency measures should provide approximately 1 year's worth of
RFP, but this amount may vary based upon appropriate facts and
circumstances of each unique nonattainment area. As discussed, states
should explain the amount of anticipated emissions reductions to be
accomplished by the contingency measures outlined in the plan. In the
rare event that an area is unable to identify contingency measures to
account for approximately 1 year's worth of emissions reductions, the
state should provide a reasoned justification why the smaller amount of
emissions reductions is appropriate.
    Comment: Commenters stated that ``excess'' emissions reductions
(i.e., emission reduction measures that are included in a modeled
attainment demonstration indicating that the area will improve air
quality to well below the standard) should not be used as contingency
measures in the event an area actually fails to attain. Commenters
asserted that the failure to attain should be considered a
demonstration that excess emissions reductions do not exist. Further,
the commenters stated that excess reductions do not provide the public
health benefit intended by Congress. Other commenters stated that
Moderate areas that cannot attain by the statutory attainment date
could also have excess emissions reductions creditable as contingency
measures.
    Response: In keeping with longstanding practice, the final rule
allows excess emissions reductions to be credited as contingency
measures in plans that demonstrate attainment but not for plans that
demonstrate an impracticability to attain. This allows nonattainment
areas to credit emissions reductions beyond those planned to satisfy
attainment plan requirements as meeting part or all of the contingency
measure requirements. This allowance is further supported by the
court's ruling in LEAN v. EPA, which found that emissions reductions in
excess of what were needed for the attainment demonstration and RFP in
ozone attainment plans are creditable for contingency measures. Because
the contingency measures requirement for both ozone and
PM2.5 originates in CAA section 172(c)(9), it is applicable
for all areas designated nonattainment for any NAAQS. Therefore, the
EPA concluded that the same approach is appropriate for Moderate
PM2.5 nonattainment areas that can demonstrate attainment by
the statutory attainment date. Allowing ``excess'' emissions reductions
affords proper credit for these areas as they continue to make progress
toward attainment while the new SIP is developed for the area.
Additionally, in support of the overarching goal of the CAA, public
health will benefit from the excess emissions reductions. However, such
an allowance for a Moderate area that cannot practicably attain is not
acceptable because all emissions reductions anticipated from control
measures while developing the attainment plan should be accounted for
in the RFP plan. With all of these reductions accounted for in the RFP
plan, there are no excess reductions beyond the attainment planning
period to be credited as contingency measures.

I. Attainment Dates

1. Summary of Proposal
    The proposal described the CAA section 188(c)(1) requirement for
Moderate areas to attain the standard as expeditiously as practicable,
but no later than the end of the sixth calendar year after the ``area's
designation as nonattainment.'' For purposes of clarity, the EPA
proposed to interpret the term ``area's designation'' as meaning ``the
area's effective date of designation,'' consistent with the agency's
past approach for implementing the 1997 and 2006 PM2.5
NAAQS, and with its approach for implementing the NAAQS for other
criteria pollutants under part D, title I of the CAA. The EPA requested
comment on this interpretation. The preamble to the proposal also
described the process for determining whether an area has attained the
NAAQS.
2. Final Rule
    The final rule maintains the requirement interpreting of CAA
section 188(c)(1) to mean that the attainment date must be as
expeditiously as practicable, but no later than the end of the sixth
calendar after the effective date of an area's designation. See
51.1004(a)(1). Thus, as an example, for areas designated nonattainment
in the first round of designations for the 2012 PM2.5 NAAQS,
the effective date of designation is April 15, 2015, and the Moderate
area attainment date would be as expeditious as practicable, but no

later than December 31, 2021 (i.e., the end of the sixth calendar year
after designation). Serious area attainment dates are discussed fully
in Section VI.I of this preamble.
    The EPA's approach to approving an attainment date for a
PM2.5 nonattainment area will be different for a Moderate
area that cannot practicably attain the relevant PM2.5 NAAQS
by the end of the sixth calendar year after designation. Given that the
agency will reclassify any such area to Serious and thereby trigger
additional Serious area requirements for the area, the EPA will approve
an attainment date for the area when it takes action on the Serious
area attainment plan submitted for the area. In the interim, before the
EPA takes action to reclassify the area, the statutory Moderate area
attainment date will continue to apply to such an area. See 40 CFR
51.1000 and 51.1004(a)(1)(ii). As discussed more fully in Section VI.I
of this preamble, when the EPA reclassifies the area, then the
presumptive attainment date for the area will be as expeditious as
practicable, but no later than the end of the tenth calendar year
following designation.
    Once an area has an approved attainment date and has implemented
its plan, the EPA has the responsibility for determining whether the
nonattainment area has attained the standard by its applicable
attainment date. Section 179(c)(1) of the CAA requires the EPA to make
determinations of attainment no later than 6 months following the
attainment date for the area. Under CAA section 179(c)(2), the EPA must
publish a notice in the Federal Register identifying those areas that
failed to attain by the applicable attainment date. The statute further
provides that the EPA may revise or supplement its determination of
attainment for the affected areas based upon more complete information
or analysis concerning the air quality for the area as of the area's
attainment date.
    Section 179(c)(1) of the CAA provides that the EPA is to base the
attainment determination for an area upon an area's ``air quality data
as of the attainment date.'' The EPA will make the determination of
whether an area's air quality is meeting the PM2.5 NAAQS by
the applicable attainment date based upon data gathered from the air
quality monitoring sites that have been entered into the EPA's Air
Quality System (AQS) database. The state is not required to make any
special or additional submission in order for EPA to make a
determination of attainment.
    A Moderate PM2.5 nonattainment area's air quality status
is determined in accordance with Appendix N of 40 CFR part 50. To show
attainment of the current 24-hour and annual standards for
PM2.5, data from the most recent 3 consecutive years prior
to the area's attainment date must show that PM2.5
concentrations over the prior 3 year period are at or below the levels
of the standards. A complete year of air quality data, as described in
part 50, Appendix N, is comprised of all 4 calendar quarters with each
quarter containing data from at least 75 percent of the scheduled
sampling days.
    The EPA will begin processing and analyzing data related to the
attainment of Moderate PM2.5 nonattainment areas after the
applicable attainment date for the affected areas. Current EPA
regulations, under 40 CFR part 58, set the deadline for the state to
submit air quality data into the AQS database as no later than 90 days
after the end of the calendar year.
    While the EPA may determine that an area's air quality data
indicate that an area may be meeting the PM2.5 NAAQS for a
specified period of time, this does not eliminate the state's
responsibility under the Act to adopt and implement an approvable
attainment plan unless the area also has been granted a clean data
determination. If the EPA determines that an area has attained the
standard as of its attainment date, the area will remain designated as
nonattainment until the state has submitted an acceptable redesignation
request and maintenance plan, and EPA has approved them.
    In order for an area to be redesignated as attainment, the state
must comply with the five requirements listed under section
107(d)(3)(E) of the CAA. Briefly, this section requires that:
    (1) The EPA has determined that the area has attained the
PM2.5 NAAQS;
    (2) The EPA has fully approved the applicable state implementation
plan;
    (3) The improvement in air quality is due to permanent and
enforceable reductions in emissions;
    (4) The EPA has fully approved a maintenance plan for the area; and
    (5) The state(s) containing the area or portions of the area have
met all applicable requirements under CAA section 110 and part D.\142\
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    \142\ See ``Procedures for Processing Requests to Redesignate
Areas to Attainment,'' Memorandum from John Calcagni, USEPA Office
of Air Quality Planning and Standards, Director, Air Quality
Management Division, September 4, 1992.
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J. Attainment Date Extensions

1. Attainment Date Extension Criteria
    a. Summary of Proposal. Subpart 4 of title I of the CAA provides
the EPA with authority to grant up to two 1-year extensions of the
attainment date for a Moderate area that otherwise could be found to
have failed to attain the relevant PM2.5 NAAQS, if the area
can meet specific statutory criteria related to monitored air quality
in the area and the implementation of measures in the attainment plan.
Under CAA section 188(d), a state may apply to the EPA for an extension
of a Moderate area's attainment date of 1 additional year (the
``Extension Year'') if ``(1) the state has complied with all
requirements and commitments pertaining to the area in the applicable
implementation plan; and (2) no more than one exceedance of the 24-hour
[NAAQS] level for PM10 has occurred in the area in the year
preceding the Extension Year, and the annual mean concentration of
PM10 in the area for such year is less than or equal to the
standard level.'' Section 188(d) of the CAA also provides for the
possibility that the EPA may grant a second 1-year extension if the
Moderate area meets specific criteria. The proposal took comment on two
ambiguous aspects of this language that warrant further interpretation
through this rule.
    First, the proposal addressed the statutory language explicitly
setting ambient air quality conditions for an attainment date extension
in terms that relate factually to the 24-hour PM10 NAAQS
that was in effect at the time of the 1990 Amendments of the CAA, which
has a statistical form that is substantially different from the 24-hour
PM2.5 NAAQS. The requirement in CAA section 188(d)(2) states
that an extension may be granted if ``no more than one exceedance of
the 24-hour national ambient air quality standard level for
PM10 has occurred in the area in the year preceding the
Extension Year, and the annual mean concentration of PM10 in
the area for such year is less than or equal to the standard level.''
The proposal noted that the form of the 2006 24-hour PM2.5
NAAQS is a percentile-based form and not a ``one expected exceedance''
form as is the PM10 NAAQS, and therefore the statutory
language requires some interpretation with regard to how it applies to
the PM2.5 NAAQS.
    The EPA included a proposed option and requested comment on two
other alternatives. The preferred proposed approach would only require
a state to demonstrate that in the year prior to the applicable
attainment date for the area, a Moderate area did not exceed the level
of (i.e., had clean data for) the specific PM2.5 NAAQS for
which the area is designated nonattainment (the ``applicable NAAQS'')
and for which the

state is seeking the extension of the attainment date. The second
approach would require that a state demonstrate that in the year prior
to the applicable attainment date for an area, the Moderate area did
not exceed the level of the specific PM2.5 NAAQS for which
the area is designated nonattainment (the applicable NAAQS), and did
not exceed the most stringent level of any other PM2.5 NAAQS
in effect nationally at the time the area was designated for the
applicable NAAQS. The third approach would require that a state
demonstrate that in the year prior to the applicable attainment date
for an area, the Moderate area did not have more than one exceedance of
the level of the 24-hour PM2.5 standard, and that the annual
mean concentration of PM2.5 in the area for the attainment
year was less than or equal to the annual standard, regardless of the
NAAQS for which the state is seeking an attainment date extension.
    Second, the proposal addressed how the language of CAA section
188(d)(2) should apply to the PM2.5 NAAQS to the extent that
it does not specify whether the air quality criteria for an attainment
date extension apply equally for a Moderate area designated
nonattainment for both the 24-hour and annual standards, or for just
one of the standards. In practice, most areas designated nonattainment
for the PM10 NAAQS following passage of the 1990 CAA
Amendments were designated nonattainment only for the 24-hour
PM10 NAAQS, with a few designated for only the annual
PM10 NAAQS or for both the 24-hour and the annual
PM10 NAAQS. The 24-hour NAAQS has served as the
``controlling'' (i.e., functionally more stringent) PM10
standard, such that the agency's experience to date in granting
PM10 Moderate area attainment date extension requests has
been limited to extending the attainment date for the 24-hour
PM10 NAAQS.\143\ The situation is distinctly different for
PM2.5 nonattainment areas, as the specific facts and
circumstances of a particular area may warrant a nonattainment
designation for either the 24-hour standard or the annual standard, but
often not both. In most cases, for instance, the current nonattainment
areas for PM2.5 are designated either for the 1997 annual
NAAQS or for the 2006 24-hour NAAQS, but not both.\144\ For example,
the EPA recently promulgated designations for areas violating only the
annual PM2.5 NAAQS revised in 2012, not the 24-hour NAAQS,
which was retained at the level established during the 2006 p.m. NAAQS
review. If a PM2.5 nonattainment area is designated only for
the 24-hour or only for the annual PM2.5 NAAQS, this
situation raises the question of how CAA section 188(d)(2) air quality
criteria for both standards should apply to such a PM2.5
NAAQS nonattainment area if the state seeks an extension of the
applicable attainment date for such area.
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    \143\ For examples of the EPA actions to extend attainment dates
for Moderate PM10 areas, see 61 FR 20730 (May 8, 1996),
61 FR 66602 (December 18, 1996), and 66 FR 32752 (June 18, 2001).
    \144\ Nonattainment areas designated for both the 24-hour and
annual PM2.5 NAAQS are located in central and southern
CA.
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    Regarding the ``requirements and commitments'' criterion, the EPA
proposed to interpret this provision to mean that the state has adopted
and is implementing the control measures in the SIP submission it made
to address the attainment plan requirements for the applicable
PM2.5 NAAQS. The proposal also described a second potential
interpretation, in which the state would not be eligible for an
attainment date extension unless it has adopted and submitted its
Moderate area SIP and has received full approval from the EPA.
    b. Final Rule. The EPA received a number of comments on the
attainment date extension criteria. With respect to the criterion
requiring compliance with all requirements and commitments in the
applicable implementation plan, several commenters agreed with the
EPA's proposed approach that the state must have adopted and submitted
its Moderate area SIP but does not need to have full approval of the
plan by the EPA in order to receive an extension. These commenters
indicated that a state should not be penalized for a failure by the EPA
to take timely action on the implementation plan. Some commenters
opposed the proposed approach, stating that an area's attainment date
is not predetermined as the end of the sixth calendar year after
designation, but instead is to be ``as expeditiously as practicable,''
and no later than the end of the sixth calendar year. For this reason,
the commenters stated that the actual attainment date to be extended
would not be known until after approval of the SIP by the EPA.
    After considering the comments received on this issue, the EPA is
finalizing an approach similar to the preferred option in the proposal.
This interpretation is based on the plain language of CAA section
188(d) that does not explicitly require that the state comply with all
requirements pertaining to the area in the CAA, but merely requires
that the state comply with all requirements in the applicable SIP.\145\
In other words, the EPA believes that CAA section 188(d)(1) should be
interpreted to mean that so long as the state has submitted the
necessary attainment plan for the area for the applicable
PM2.5 NAAQs and is implementing the control measures in the
submission, the fact that the EPA has not yet acted on such submission
to make it an approved part of the applicable SIP should not be a
barrier to the state obtaining an extension of the attainment date
under CAA section 188(d)(1). See section 51.1005(a)(1) of the CAA. For
the same reason, the EPA also proposes to read this provision not to
bar an extension if all or part of an area's Moderate area plan is
disapproved or has been promulgated by the EPA as a FIP. In the case
that the ``applicable implementation plan'' is a FIP (or combination of
SIP and FIP), then the EPA requires the state to have implemented the
control measures contained therein in order to meet the statutory
criteria at CAA section 188(d)(1) for a Moderate area attainment date
extension.
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    \145\ This interpretation as applied to CAA section 188(e) for
Serious area attainment date extensions was upheld by the Ninth
Circuit Court of Appeals in Vigil v. Leavitt, 366 F.3d 1025, amended
at 381 F.3d 826 (9th Cir. 2004).
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    With respect to the air quality criterion, several commenters
supported the EPA's preferred option because it would require an area
to show clean data only for the specific standard for which it is
seeking an extension year. Some commenters acknowledged that a literal
reading of the statute may seem to require a showing of clean data for
both the annual and 24-hour PM2.5 standards in order to
receive an extension, but suggested that this interpretation would not
make sense under the circumstance where the two standards have
different attainment dates. The commenter believed it would lead to
absurd results if, in order to receive an extension for one standard,
an area were required to show clean data for the other standard for
which the attainment date had not yet passed. On the other hand, other
commenters favored the option that would require clean data for both
standards in order to obtain an extension for one standard because they
believed that only requiring clean data for one standard would allow
the area to avoid or delay achieving additional emissions reductions.
    After considering the comments on the air quality criterion, the
EPA has decided to finalize the approach that would require an area to
show clean data during the attainment year only for

the specific standard for which it is seeking an extension. See 40 CFR
51.1005(a)(1). Under this approach, the EPA interprets the requirement
to demonstrate that the area had ``no more than one exceedance'' of the
24-hour PM2.5 NAAQS to mean that the state must simply
demonstrate that the area had ``clean data'' in the attainment year.
Thus, a state seeking an attainment date extension for a Moderate
nonattainment area for a 24-hour PM2.5 NAAQS would be
required to demonstrate that the area had clean data with respect to
the statistical form of that particular standard (i.e., for the 2006
PM2.5 NAAQS, the 98th percentile value did not exceed 35
[mu]g/m\3\) in the calendar year prior to the applicable attainment
date for the area. The state would not have to demonstrate that the
area also had clean data for any other PM2.5 NAAQS,
including any annual PM2.5 NAAQS or later revision of the
24-hour PM2.5 NAAQS. Likewise, a state seeking an attainment
date extension for an annual PM2.5 NAAQS would be required
to demonstrate that the area had clean data for that particular
standard (i.e., for the 2012 annual PM2.5 NAAQS, the annual
mean value did not exceed 12.0 [mu]g/m\3\) in the calendar year prior
to the applicable attainment date for the area, but would not have to
demonstrate that the area had clean data for any other PM2.5
NAAQS.
    The EPA believes this interpretation of CAA section 188(d)(2) is
appropriate for two main reasons. First, while most PM10
nonattainment areas were designated nonattainment for either just the
24-hour PM10 NAAQS or for both the 24-hour and annual
PM10 NAAQS, the majority of current PM2.5
nonattainment areas are, in contrast, designated for either the 24-hour
or the annual PM2.5 NAAQS, and should arguably only need to
demonstrate clean data for the NAAQS for which the area is designated
nonattainment. For those few PM2.5 nonattainment areas
designated for both 24-hour and annual PM2.5 NAAQS, the EPA
believes it also is appropriate that a state must only demonstrate
clean data for the specific NAAQS for which the state is seeking an
attainment date extension because such an approach is consistent with
the statute's overall approach to designating nonattainment areas and
implementing control strategies for each separate PM2.5
NAAQS. Second, if an area is designated as nonattainment for both the
24-hour and annual PM2.5 standards and receives an extension
for one standard while still working toward a later attainment date for
the other standard, public health protection would not be delayed
because the state would still be subject to the ongoing mandate to
adopt and implement measures to ensure expeditious attainment of the
other standard.
    c. Comments and Responses. Any additional comments received on this
section are addressed in the Response to Comments document found in the
docket for this action.
2. Process for Attainment Date Extension Request Submissions
    a. Summary of Proposal. The proposal recognized that CAA section
188(d) does not specify the process by which the state should submit a
Moderate area attainment date extension request, nor how the EPA should
evaluate and act upon such a request. The proposal described the
elements that the state would be required to submit for the various
options proposed regarding the CAA section 188(d) extension criteria
for 1) compliance with requirements and commitments in the applicable
SIP, and 2) air quality data. The proposal suggested that any Moderate
area extension request should be submitted to the EPA by the attainment
date for the area (i.e., by December 31 of the attainment year), and it
proposed requiring the state to submit certified air quality data for
the attainment year to the EPA by February 28 of the following year in
order for the EPA to issue a determination within 6 months of the
attainment date regarding whether the area attained or failed to
attain. The proposal stated that an attainment date extension should be
granted only after the agency provides notice in the Federal Register
and an opportunity for the public to comment. Lastly, the proposal
clarified that any 1-year extension would extend from January 1 to
December 31 for the year following the year including the December 31
attainment date.
    b. Final Rule. As discussed in the previous section, in order for
the EPA to make a decision on whether to grant a 1-year attainment date
extension, the state needs to submit sufficient information to
demonstrate that it has both complied with applicable requirements and
commitments in the applicable implementation plan, and that it has
clean data for the attainment year. Under the final rule, a state would
have to demonstrate that control measures have been submitted in the
form of a SIP revision, and that RACM and RACT and additional
reasonable measures for sources in the area have been implemented. The
SIP revision would need to have been adopted and submitted by the
state, but it would not need to have been approved by the EPA in order
for the state to qualify for an extension. See 40 CFR 51.1005(a)(1)(i).
The state also would need to have ``clean'' air quality data in the
attainment year, as explained in the previous section. See 40 CFR
51.1005(a)(1)(ii)-(iii). Any decision made by the EPA to extend the
attainment date for an area would be based on facts specific to the
nonattainment area at issue.
    Some commenters suggested that in some cases a state will not know
if it should seek an extension request until after the attainment date
has passed, particularly for areas that commonly have higher air
quality levels in the cooler months at the end of the calendar year.
The commenter recommended that states should have until February 28 of
the following year to submit an extension request along with certified
air quality data. Other commenters stated that there is no legal basis
for requiring the certification of monitoring data by February 28th of
the following year, and therefore it should not be a requirement that
could potentially disqualify a state from having an extension request
be approved.
    The EPA considered these comments in light of the EPA's obligation
under the CAA to issue a determination of attainment or failure to
attain within 6 months of the original attainment date. After
considering these comments, the EPA strongly recommends that a state
should submit a Moderate area 1-year extension request to the
appropriate EPA Regional Office by February 28 of the following year.
In addition, the EPA strongly recommends that the state provide
certified air quality data for the previous calendar year by this date
or as close to this date as possible. The EPA understands that there
may be certain situations that prevent the full certification of
filter-based PM2.5 monitoring data by this date. If air
quality data for the previous full calendar year has not been fully
certified by February 28, the extension request should include any
available preliminary data the state can provide. Submission of the
necessary air quality data must occur as soon as possible after the
attainment date to enable the EPA to review the state's request
expeditiously and take appropriate action on the request prior to the
date by which the EPA is required to make a determination that the area
failed to attain by its Moderate area attainment date, i.e., within 6
months of the applicable attainment date (see the discussion of
reclassification in Section V of this preamble).
    As indicated in the proposal, the EPA believes that an attainment
date

extension should only be granted after the agency provides notice in
the Federal Register and an opportunity for the public to comment. A
notice-and-comment rulemaking allows for the EPA to adequately evaluate
whether the area meets the air quality and program implementation
criteria, and to consider other relevant facts and information
presented by the state and the public in determining whether the
extension request should be granted or denied. This process also is
consistent with past practice by the EPA in granting attainment date
extensions, most recently for ozone nonattainment areas.
    Regarding the extension period, the EPA interprets CAA section
188(d) to authorize the EPA to stipulate that any extension would begin
on January 1 and end on December 31 of the extension year, and these
dates would not depend on when the state submitted its request for an
extension or was granted the extension by the EPA. The EPA is
finalizing this interpretation at 40 CFR 51.1005(a)(4). The EPA
believes this is a reasonable approach, as the original attainment date
for the area will either be the end of the sixth calendar year
following designation of the area, or the end of an earlier calendar
year if the state demonstrated that it could advance attainment by at
least 1 year. In addition, compliance with the relevant NAAQS will be
evaluated based on monitored data collected over a full calendar year
(i.e., over the period beginning January 1 and ending December 31), so
starting the extension year on January 1 is logical.
    As noted earlier in this discussion of Moderate area attainment
date extensions, CAA section 188(d) provides that a state may seek up
to two 1-year extensions of the Moderate area attainment date if it
meets the applicable criteria of CAA sections 188(d)(1) and 188(d)(2).
The statute makes no distinction between the criteria that must be met
for the first 1-year extension and the criteria for the second 1-year
extension. Therefore, for a second 1-year attainment date extension
request, the EPA intends to apply the same interpretations of the
statutory criteria as described earlier in this section, including the
recommended deadlines for the state to submit the extension request and
the certified air quality data.
    c. Comments and Responses. Comment: Some commenters described the
situation where the EPA has approved a Moderate area attainment date
that is earlier than the latest date allowed by the statute (for
example, assume the approved attainment date is the end of the 5th
calendar year after designation). The commenter suggested that if the
area was unable to attain by its ``earlier'' approved attainment date,
CAA section 188(d) should be interpreted in a way that would not
require the state to submit a request for an attainment date extension.
The commenter suggested that the state should only be required to meet
the CAA section 188(d) requirements if the area is seeking an extension
beyond the latest Moderate area attainment date allowed by statute
(i.e. the end of the sixth calendar year after designations).
    Response: The EPA does not agree with the commenter because the
statute appears to address this situation clearly. Section 188(c)(1) of
the CAA states that the Moderate area attainment date is ``as
expeditiously as practicable but no later than the end of the sixth
calendar year after the area's designation as nonattainment.'' If the
area had provided an attainment demonstration supporting the approval
of an earlier attainment date by the EPA, then that approved attainment
date is then regarded as the ``applicable attainment date'' for that
area. Section 188(d)(1) of the CAA of the statute then enables the EPA
to grant a 1-year extension for the ``date specified in paragraph
(c)(1),'' which in this case would be the earlier attainment date.

V. Reclassification of a PM2.5 Moderate Nonattainment Area
to Serious

    As discussed elsewhere in this preamble, subpart 4, part D of title
I of the CAA establishes a two-tier classification system for areas
designated nonattainment for the PM2.5 NAAQS. While all
areas designated nonattainment are initially classified as Moderate,
CAA section 188(b) describes two pathways by which the EPA has the
authority and/or the duty to reclassify a Moderate nonattainment area
to a Serious nonattainment area. Pursuant to CAA section 188(b)(1), the
EPA has general discretionary authority to reclassify from Moderate to
Serious any area that the Administrator determines cannot practicably
attain the NAAQS by the applicable Moderate area attainment date.
Pursuant to CAA section 188(b)(2), the EPA has a mandatory duty to
reclassify from Moderate to Serious any area that fails to attain the
NAAQS by the applicable Moderate area attainment date. Both of these
pathways are more fully described in the following sections.\146\
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    \146\ Note that a reclassification for a multi-state
nonattainment area will be done in a single action by the EPA;
separate actions are not needed to reclassify the portion of each
state comprising the multi-state nonattainment area.
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A. Discretionary Authority

1. Summary of Proposal
    The proposal provided background on the EPA's discretionary
authority to reclassify a Moderate area to Serious. It proposed to
interpret the statute to give EPA broad authority to reclassify based
on available information, noting that the EPA could base this
determination upon whatever factors are pertinent. The proposal sought
comment on whether EPA should discretionarily reclassify an area
without a request or submission from the affected state. The proposal
also addressed the mandatory statutory timing for discretionary
reclassification (i.e., within 18 months of the moderate area SIP due
date), and took comment on the appropriateness of EPA acting to
reclassify an area beyond 18 months after the Moderate area SIP due
date, including right up to the Moderate area attainment date.
2. Final Rule
    The final rule remains largely unchanged with regard to this issue.
The EPA's discretionary authority to reclassify a Moderate area to
Serious derives from language in section 188(b)(1) of the CAA, which
provides that: ``The Administrator may reclassify as a Serious
PM10 nonattainment area . . . any area that the
Administrator determines cannot practicably attain the [NAAQS] . . . by
the attainment date . . . for Moderate Areas.'' The use of this
discretionary authority thus would be triggered by the EPA making a
determination that the Moderate area in question cannot practicably
attain by its statutory attainment date.
    The CAA does not specify the basis on which the EPA may make a
determination that the area cannot practicably attain by the applicable
attainment date. In the General Preamble, the EPA explained that the
agency could base this determination upon whatever facts are pertinent,
and could do so whether or not the state in question has submitted a
Moderate area attainment plan, and whether or not the state has made
the demonstration contemplated in CAA section 189(a)(1)(B).\147\ The
EPA may make such a determination based on evaluation of the attainment
plan for the Moderate area in question, or based on other facts known
to the agency. As discussed earlier in this preamble, the attainment
plan that a state would submit for a Moderate nonattainment area must
include either a demonstration that the area will attain the NAAQS by
the

statutory Moderate area attainment date or a demonstration that
attaining by the statutory Moderate area attainment date is
impracticable. If the state makes and the EPA concurs with an
impracticability demonstration submitted as part of the attainment
plan, then the demonstration could serve as the basis for the EPA
initiating a notice-and-comment rulemaking to reclassify the area to
Serious.
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    \147\ See the Federal Register published on April 16, 1994 (57
FR 13498, 13537 and 13538).
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    However, the CAA does not specify the basis for the EPA's exercise
of its discretionary authority and does not require the EPA to make its
determination based on a submission from the state. Indeed, such a
prerequisite would be illogical in the case of a state that fails to
make any attainment plan submission or fails to address the issue of
the need for reclassification in such submission. The EPA believes that
while a Moderate area impracticability demonstration as contemplated in
CAA section 189(a)(1)(B) is desirable in order to help the agency make
a determination that the area cannot practicably attain by its
attainment date, such a demonstration is not necessary to trigger
action by the EPA to reclassify a Moderate area to Serious. The statute
does not prohibit the EPA from using the weight of available evidence,
including information available in the public record of a state, to
make such a determination, even in the absence of a complete attainment
plan submission.
    Regarding the timing of discretionary reclassifications, CAA
section 188(b)(1)(B) establishes timeframes by which EPA is to act if
it intends to exercise its discretionary authority to reclassify areas
as appropriate following the Moderate area attainment plan due date,
stating that ``the Administrator shall reclassify appropriate areas
within 18 months after the required date for the state's submission of
a SIP for the Moderate Area.'' In the case of areas designated
nonattainment for the 2012 PM2.5 NAAQS in the first round of
designations, states will be required by statute to submit a Moderate
area attainment plan within 18 months of the date of designation (April
2015), or no later than October 2016. Pursuant to CAA section
188(b)(1)(B), the EPA would then have until April 2018 (18 months
following the Moderate area attainment plan submission deadline) to use
its discretionary authority to reclassify any area that the EPA
determines at that time cannot practicably attain by the Moderate area
attainment date of December 2021.
    However, as noted earlier, there may be situations in which it may
be appropriate to reclassify an area at a point in time more than 18
months after the SIP due date. On this issue, the General Preamble
stated that:

    ``. . . under the plain meaning of the terms of section
188(b)(1), EPA has general discretion to reclassify at any time
before the applicable attainment date any area EPA determines cannot
practically attain the standards by such date. Accordingly, CAA
section 188(b)(1) is a general expression of delegated rulemaking
authority. In addition, subparagraphs (A) and (B) of CAA section
188(b)(1) mandate that the EPA reclassify at specified timeframes
any areas it determines appropriate for reclassification at those
dates. These subparagraphs do not restrict the general authority but
simply specify that, at a minimum, it must be exercised at certain
times.'' \148\
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    \148\ Ibid. at 13537.

    The EPA continues to consider this the correct interpretation of
the statutory requirements concerning its authority to reclassify a
Moderate nonattainment area to Serious at any time prior to the area's
Moderate area attainment date, if the agency determines that the area
cannot practicably attain the relevant PM2.5 NAAQS by that
date. See Section VI.A.2 of this preamble for a discussion of the due
dates for submission of attainment plan elements for areas that receive
a discretionary reclassification.
    The EPA emphasizes that a state with an area designated as
nonattainment for the PM2.5 NAAQS is required to meet all
Moderate area attainment plan requirements, even after the EPA
reclassifies the area to Serious. Section 189(b)(1) of the CAA states
clearly that ``in addition to'' the Moderate area attainment plan
requirements, states with areas reclassified to Serious must also meet
Serious area attainment plan requirements, i.e., the reclassification
does not eliminate the statutory obligation to meet Moderate area
attainment plan requirements.\149\ Thus, the EPA believes that
reclassifying Moderate areas to Serious at any time under its
discretionary authority does not provide incentives to delay
development and implementation of control measures by excusing states
from meeting substantive Moderate area attainment plan requirements or
by extending the applicable attainment date. The EPA articulated this
position in the General Preamble, explaining that this interpretation:
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    \149\ See, Vigil v. Leavitt, 366 F.3d 1025, amended at 381 F.3d
826 (9th Cir. 2004).

    . . . creates an incentive for the timely submittal and
effective implementation of moderate area SIP requirements and
facilitates the PM10 attainment objective. For example,
if an area that fails to submit a timely moderate area SIP is
reclassified, this does not obviate the requirement that the area
submit and implement RACM consistent with the moderate area
schedule. Accordingly, the area could be subject to sanctions for
its delay in submitting the RACM SIP requirement . . . Further,
reclassification before the applicable attainment date will ensure
that additional control measures (i.e., in addition to RACM, serious
areas must implement best available control measures (BACM)), are
implemented sooner and will expedite the application of more
stringent new source review requirements to the area . . .
Similarly, where an area submits a timely moderate area SIP, EPA may
not discover that the area cannot practicably attain until sometime
after it begins implementing its moderate area control measures. The
EPA then may want to reclassify the area in order to facilitate the
development and implementation of BACM.\150\
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    \150\ 57 FR 13498 (April 16, 1992), at page 13537.

    The EPA considers this longstanding interpretation of CAA section
188(b)(1) to be the correct interpretation of the statutory
requirements governing the discretionary reclassification of Moderate
areas. The EPA will reclassify any area it determines cannot
practicably attain by the Moderate area attainment date through notice-
and-comment rulemaking. See 40 CFR 51.1002(b)(1).
3. Comments and Responses
    Comment: Some commenters stated that while it may be desirable for
a state or local agency to provide an impracticability demonstration to
the EPA, the EPA is not prohibited from using the weight of available
evidence to reclassify an area to Serious even before the Moderate area
plan is due if it has a particularly challenging air quality situation.
Other commenters did not agree with the EPA's interpretation of the
statute, and believed that the EPA's authority should be limited to
reclassification of areas that submit an impracticability
demonstration.
    Response: For the reasons described earlier, the EPA agrees with
the first commenter and does not believe its authority is limited in
the manner suggested by the second commenter.

B. Mandatory Duty

1. Summary of Proposal
    The proposal provided background on the EPA's mandatory duty
pursuant to CAA section 188(b)(2) to reclassify a Moderate area to
Serious when the area fails to attain the standard by the attainment
date. The CAA directs the EPA to reclassify an area from Moderate to
Serious if the area fails to attain the relevant NAAQS by the
applicable Moderate area attainment date

(including any attainment date that had been extended by one or 2 years
pursuant to CAA section 188(d)). Reclassification occurs by operation
of law when the EPA determines that the area failed to attain the NAAQS
by the applicable attainment date, in accordance with CAA section
188(b)(2)(A). Section 188(b)(2) of the CAA requires that ``within six
months following the applicable attainment date for a PM10
nonattainment area, the Administrator shall determine whether the area
attained the standard by that date'' and publish its determination in
the Federal Register.
    The EPA proposed that the date of reclassification would be the
effective date of the Federal Register notice issued by the EPA that
determines the area failed to attain by the attainment date. Thus, for
example in the case of the 2012 PM2.5 NAAQS, assuming a
Moderate PM2.5 nonattainment area fails to attain the
standard by its approved attainment date of December 31, 2021, the EPA
would be required to publish in the Federal Register no later than June
30, 2022 its determination that the area failed to attain the NAAQS and
is therefore reclassified as Serious by operation of law. The actual
date of reclassification for the area would be the effective date of
the Federal Register document (e.g. in July or August 2022). To meet
the requirements of CAA section 189(b)(2), the Serious area attainment
plan for the area would be due within 18 months of the actual
reclassification date (i.e., in early 2024).
    The proposal also discussed a possible alternative option, which
would be to consider the date of reclassification to Serious to be the
same as the Moderate area attainment date. Applying this approach in
the example earlier would yield an earlier date of reclassification of
December 31, 2021, and an earlier Serious area attainment plan due date
of June 30, 2023.
2. Final Rule
    Several commenters supported the EPA's proposed approach to
interpret the date of reclassification as the effective date of the
Federal Register notice announcing the area had failed to attain the
standard by the Moderate area attainment date because this approach
would allow adequate time for the EPA to evaluate air quality data and
any exceptional events claims before making the determination that the
area failed to attain. Some commenters opposed the proposed approach
and supported interpreting the date of reclassification as being the
same as the missed attainment date for the Moderate area. This
commenter suggested that the proposed approach could introduce
additional delay because the EPA does not always issue determinations
of failure to attain promptly. They also claimed that the term
``reclassified by operation of law'' in CAA section 188(b)(2)(A) would
have no meaning (i.e., surplusage) if the proposed approach was
adopted.
    After taking the comments received under consideration, the EPA has
decided to retain the proposed approach. The date of reclassification
is the effective date of the Federal Register notice issued by the EPA
that determines the area failed to attain by the attainment date. For
practical reasons, the EPA does not believe that as a general matter it
can be expected to make a determination on December 31 that an area
failed to attain. Because the PM2.5 ambient monitoring
method requires laboratory analysis of filters prior to determining the
ambient mass for each day, adequate time is needed after December 31 to
ensure that the filter-based measurements have been evaluated and
quality-assured in an accurate manner.
    Although CAA section 188(b)(2) does not explicitly address this
issue, the EPA believes that this approach is a reasonable
interpretation of statutory ambiguity in CAA section 188(b)(2) and
preferable over the alternative approach for two additional reasons.
First, the statute at CAA section 189(b)(2) gives a state 18 months
from the date of reclassification of an area to submit for the EPA's
approval an attainment demonstration with air quality modeling and
provisions to assure timely implementation of BACM and BACT on sources
in the nonattainment area. The workload associated with developing a
Serious area plan can be substantial, and the EPA believes that it is
reasonable to resolve the statutory ambiguity in favor of providing the
state with the full 18 months from the effective date of
reclassification to develop and submit a thorough, complete and
accurate Serious area attainment plan that will provide for expeditious
attainment of the NAAQS.
    Second, the statutory attainment date for a Serious area
reclassified under any circumstances is as expeditious as practicable
but no later than the end of the tenth year following designation of
the area, and is thus independent of the date of reclassification of
the area. Allowing a state some additional amount of time beyond 18
months from the missed attainment date to develop and submit a complete
Serious area attainment plan, including adopting BACM and BACT, will
not change the statutory obligation on the state for the area to attain
the relevant NAAQS by the applicable attainment date. On the contrary,
the EPA believes that the extra time may in fact help the area timely
attain the relevant NAAQS by allowing the state to develop a more
effective attainment plan for the area.
    Thus, the EPA interprets the CAA such that the date of
reclassification for an area reclassified under the EPA's mandatory
duty is to be considered the effective date of the Federal Register
document announcing that the area had not attained the relevant
PM2.5 NAAQS and is therefore reclassified by operation of