Proposed Rule2025-20409
Air Plan Approval; Pennsylvania; Redesignation Request for the Allegheny County Area for the 2012 Annual Fine Particulate Matter Standard
Primary source
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Published
November 20, 2025
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is proposing to approve a request from the Commonwealth of Pennsylvania to redesignate the Allegheny County, Pennsylvania nonattainment area (Allegheny County Area) to attainment for the 2012 annual fine particulate matter (PM<INF>2.5</INF>) national ambient air quality standard (NAAQS or standard). The EPA has already approved, as a revision to the Pennsylvania state implementation plan (SIP), a maintenance plan that demonstrates maintenance of the 2012 annual PM<INF>2.5</INF> NAAQS through 2035 in the Allegheny County Area. The redesignation request was submitted by the Commonwealth of Pennsylvania Department of Environmental Protection (PADEP or Pennsylvania) on behalf of the Allegheny County Health Department (ACHD). This action is being taken under the Clean Air Act (CAA).
Full Text
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<title>Federal Register, Volume 90 Issue 222 (Thursday, November 20, 2025)</title>
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[Federal Register Volume 90, Number 222 (Thursday, November 20, 2025)]
[Proposed Rules]
[Pages 52319-52327]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-20409]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 81
[EPA-R03-OAR-2025-1777; FRL-12985-01-R3]
Air Plan Approval; Pennsylvania; Redesignation Request for the
Allegheny County Area for the 2012 Annual Fine Particulate Matter
Standard
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve a request from the Commonwealth of Pennsylvania to redesignate
the Allegheny County, Pennsylvania nonattainment area (Allegheny County
Area) to attainment for the 2012 annual fine particulate matter
(PM<INF>2.5</INF>) national ambient air quality standard (NAAQS or
standard). The EPA has already approved, as a revision to the
Pennsylvania state implementation plan (SIP), a maintenance plan that
demonstrates maintenance of the 2012 annual PM<INF>2.5</INF> NAAQS
through 2035 in the Allegheny County Area. The redesignation request
was submitted by the Commonwealth of Pennsylvania Department of
Environmental Protection (PADEP or Pennsylvania) on behalf of the
Allegheny County Health Department (ACHD). This action is being taken
under the Clean Air Act (CAA).
DATES: Written comments must be received on or before December 22,
2025.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R03-
[[Page 52320]]
OAR-2025-1777 at <a href="http://www.regulations.gov">www.regulations.gov</a>, or via email to
<a href="/cdn-cgi/l/email-protection#b9ded6cbddd6d797d4d0d2dcf9dcc9d897ded6cf"><span class="__cf_email__" data-cfemail="71161e03151e1f5f1c181a14311401105f161e07">[email protected]</span></a>. For comments submitted at <a href="http://Regulations.gov">Regulations.gov</a>, follow
the online instructions for submitting comments. Once submitted,
comments cannot be edited or removed from <a href="http://Regulations.gov">Regulations.gov</a>. For either
manner of submission, the EPA may publish any comment received to its
public docket. Do not submit electronically any information you
consider to be confidential business information (CBI) or other
information whose disclosure is restricted by statute. Multimedia
submissions (audio, video, etc.) must be accompanied by a written
comment. The written comment is considered the official comment and
should include discussion of all points you wish to make. The EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e., on the web, cloud, or other file sharing
system). For additional submission methods, please contact the person
identified in the FOR FURTHER INFORMATION CONTACT section. For the full
EPA public comment policy, information about CBI or multimedia
submissions, and general guidance on making effective comments, please
visit <a href="http://www.epa.gov/dockets/commenting-epa-dockets">www.epa.gov/dockets/commenting-epa-dockets</a>.
FOR FURTHER INFORMATION CONTACT: Ian Neiswinter, Planning &
Implementation Branch (3AD30), Air & Radiation Division, U.S.
Environmental Protection Agency, Region III, 1600 John F. Kennedy
Boulevard, Philadelphia, Pennsylvania 19103. The telephone number is
(215) 814-2011. Mr. Neiswinter can also be reached via electronic mail
at <a href="/cdn-cgi/l/email-protection#85ebe0ecf6f2ecebf1e0f7abece4ebc5e0f5e4abe2eaf3"><span class="__cf_email__" data-cfemail="f19f94988286989f859483df98909fb1948190df969e87">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this document, wherever ``we,''
``us,'' or ``our'' are used, it is intended to refer to the EPA.
I. What action is the EPA proposing?
In this action, the EPA is proposing to approve Pennsylvania's
September 4, 2025 redesignation request as satisfying the requirements
of CAA section 107(d)(3)(E) and redesignate the Allegheny County Area
\1\ from nonattainment to attainment of the 2012 annual
PM<INF>2.5</INF> NAAQS. The EPA has already approved, as a revision to
Pennsylvania's SIP, a maintenance plan that demonstrates maintenance of
the 2012 annual PM<INF>2.5</INF> NAAQS through 2035 in the Allegheny
County Area. See 90 FR 34770 (July 24, 2025).
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\1\ The Allegheny County Area is comprised of all municipalities
within Allegheny County, Pennsylvania. The table listed at 40 Code
of Federal Regulations (CFR) 81.339 defines NAAQS area designations
within Pennsylvania.
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II. Background
Fine particulate pollution can be emitted directly from a source
(primary PM<INF>2.5</INF>) or formed secondarily through chemical
reactions in the atmosphere involving precursor pollutants emitted from
a variety of sources. The main precursors of secondary PM<INF>2.5</INF>
are sulfur dioxide (SO<INF>2</INF>), nitrogen oxides (NO<INF>X</INF>),
ammonia (NH<INF>3</INF>), and volatile organic compounds (VOCs).\2\
Sulfates are a type of secondary particulate formed from SO<INF>2</INF>
emissions from power plants and industrial facilities. Nitrates,
another common type of secondary particulate, are formed from
combustion emissions of NO<INF>X</INF> from power plants, mobile
sources, and other combustion sources.
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\2\ See 81 FR 58010 (August 24, 2016).
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On January 15, 2013 (78 FR 3086), the EPA promulgated a revised
primary annual PM<INF>2.5</INF> NAAQS to provide increased protection
of public health from fine particle pollution. In that action, the EPA
strengthened the primary annual PM<INF>2.5</INF> standard from 15.0
micrograms per cubic meter ([micro]g/m\3\) to 12.0 [micro]g/m\3\, which
is attained when the 3-year average of the annual arithmetic means does
not exceed 12.0 [micro]g/m\3\. On January 15, 2015 (80 FR 2206), the
EPA published air quality designations for the 2012 annual
PM<INF>2.5</INF> NAAQS. In that action, the EPA designated all
municipalities in Allegheny County, Pennsylvania (Allegheny County
Area) as one moderate nonattainment area for the 2012 annual
PM<INF>2.5</INF> NAAQS. See 40 CFR 81.339.
On March 16, 2022 (87 FR 14799), the EPA determined that the
Allegheny County Area had clean data and attained the 2012 annual
PM<INF>2.5</INF> NAAQS based on certified air quality data from 2018-
2020. That action suspended the requirement for the Allegheny County
Area to submit an attainment demonstration and associated reasonably
available control measures (RACM), including reasonably available
control technology (RACT), a reasonable further progress (RFP) plan,
and contingency measures for failure to attain or meet RFP. These
requirements are suspended for so long as the Allegheny County Area
continues to attain the standard. When the Area is redesignated to
attainment, these requirements are permanently discharged. Nonetheless,
the EPA approved most elements of Pennsylvania's comprehensive plan to
ensure timely attainment of the 2012 annual PM<INF>2.5</INF> NAAQS for
the Allegheny County Area (Allegheny County PM<INF>2.5</INF> Attainment
Plan), including an attainment demonstration, a RACM/RACT analysis, and
an RFP analysis, along with a 2011 base year emissions inventory, a
particulate matter precursor contribution demonstration, quantitative
milestones to ensure timely attainment, and a motor vehicle emissions
budget (MVEB) specific to the 2012 annual PM<INF>2.5</INF> NAAQS.\3\ On
May 19, 2023 (88 FR 32117), the EPA determined that the Allegheny
County Area had attained the 2012 annual PM<INF>2.5</INF> NAAQS by the
applicable attainment date based on certified air quality data from
2019-2021.
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\3\ See 86 FR 26388 (May 14, 2021).
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On July 24, 2025 (90 FR 34770), the EPA approved, as a revision to
the Pennsylvania SIP, a maintenance plan that demonstrates maintenance
of the 2012 annual PM<INF>2.5</INF> NAAQS through 2035 in the Allegheny
County Area.
III. The EPA's Requirements for Redesignation to Attainment
The CAA provides the requirements for redesignating a nonattainment
area to attainment. Specifically, section 107(d)(3)(E) of the CAA
allows for redesignation provided that: (1) the EPA determines that the
area has attained the applicable NAAQS; (2) the EPA has fully approved
the applicable implementation plan for the area under section 110(k);
(3) the EPA determines that the improvement in air quality is due to
permanent and enforceable reductions in emissions resulting from
implementation of the applicable SIP and applicable Federal air
pollutant control regulations and other permanent and enforceable
reductions; (4) the EPA has fully approved a maintenance plan for the
area as meeting the requirements of section 175A of the CAA; and (5)
the state containing such area has met all requirements applicable to
the area under section 110 and part D of the CAA. Each of these
requirements are discussed in section IV of this document.
The EPA has provided guidance on redesignations in the ``SIPs;
General Preamble for the Implementation of title I of the CAA
Amendments of 1990,'' (the General Preamble) \4\ and has provided
further guidance on processing redesignation requests in the following
documents: (1) ``Procedures for Processing Requests to Redesignate
Areas to Attainment,'' Memorandum from John Calcagni, Director, Air
Quality Management Division, September 4, 1992 (hereafter referred to
as the 1992 Calcagni Memorandum or
[[Page 52321]]
Calcagni Memo); (2) ``SIP Actions Submitted in Response to CAA
Deadlines,'' Memorandum from John Calcagni, Director, Air Quality
Management Division, October 28, 1992; and (3) ``Part D New Source
Review (Part D NSR) Requirements for Areas Requesting Redesignation to
Attainment,'' Memorandum from Mary D. Nichols, Assistant Administrator
for Air and Radiation, October 14, 1994. These documents are included
in the docket for this proposed action.
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\4\ See 57 FR 13498 (April 16, 1992).
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IV. The EPA's Analysis of Pennsylvania's Submittal
The EPA is proposing to redesignate the Allegheny County Area to
attainment for the 2012 annual PM<INF>2.5</INF> NAAQS. The EPA's
proposed approval of the state's redesignation request is based upon
the EPA's determination that the Allegheny County Area continues to
attain the 2012 annual PM<INF>2.5</INF> NAAQS and that all other
redesignation criteria have been met for the Allegheny County Area. The
following is description of how Pennsylvania's September 4, 2025
submission satisfies the requirements of section 107(d)(3)(E) of the
CAA for the 2012 annual PM<INF>2.5</INF> NAAQS.
A. Attainment
To redesignate an area from nonattainment to attainment, the CAA
requires the EPA to determine that the area has attained the applicable
NAAQS (CAA section 107(d)(3)(E)(i)). Under the EPA's regulations at 40
CFR 50.18 and 40 CFR part 50, appendix N, the 2012 annual
PM<INF>2.5</INF> NAAQS is met when the annual PM<INF>2.5</INF> NAAQS
design value (DV) is less than or equal to 12.0 [micro]g/m\3\ at all
monitoring sites in the area.\5\ The relevant data must be collected
and quality-assured in accordance with 40 CFR part 58 and recorded in
the EPA Air Quality System (AQS) database.
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\5\ The annual PM<INF>2.5</INF> NAAQS design value (DV) is the
3-year average of PM<INF>2.5</INF> annual mean mass concentrations.
Three years of valid annual means are required to produce a valid
annual PM<INF>2.5</INF> NAAQS design value. A year meets data
completeness requirements when at least 75 percent of the scheduled
sampling days for each quarter have valid data. See 40 CFR part 50,
appendix N.
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As referenced previously, on March 16, 2022 (87 FR 14799), the EPA
determined that the Allegheny County Area had clean data and attained
the 2012 annual PM<INF>2.5</INF> NAAQS based on certified air quality
data from 2018-2020. Additionally, on May 19, 2023 (88 FR 32117), the
EPA determined that the Allegheny County Area had attained the 2012
annual PM<INF>2.5</INF> NAAQS by the applicable attainment date based
on certified air quality data from 2019-2021. The basis and effect of
these determinations of attainment for the 2012 annual PM<INF>2.5</INF>
NAAQS were discussed in the publications of the proposed and final
rules which determined the Allegheny County Area attained the 2012
PM<INF>2.5</INF> NAAQS.\6\
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\6\ See notice of the proposed rulemakings at 86 FR 49497
(September 3, 2021) and 88 FR 8249 (February 8, 2023).
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In addition, the EPA has reviewed the most recent ambient air
quality PM<INF>2.5</INF> monitoring data in the Allegheny County Area
consistent with the requirements contained in 40 CFR part 58 and
recorded in the EPA's AQS. The quality-assured, quality-controlled, and
state-certified 2018 to 2024 PM<INF>2.5</INF> air quality data show
that the Allegheny County Area attained and continues to attain the
2012 annual PM<INF>2.5</INF> NAAQS. Therefore, the EPA is proposing to
determine that the Allegheny County Area is attaining the 2012 annual
PM<INF>2.5</INF> NAAQS. This proposed determination is based on the
most recent three years of complete, quality-assured, quality-
controlled, and certified data, which is for the 2022-2024 monitoring
period. The monitoring data is summarized in Tables 1 and 2, in this
document, and is also included in the docket for this rulemaking
available online at <a href="http://www.regulations.gov">www.regulations.gov</a>, Docket ID: EPA-R03-OAR-2025-
1777.
Table 1--2018 to 2024 Annual Weighted Means for the Allegheny County Area for the 2012 Annual PM2.5 NAAQS ([micro]g/m\3\)
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Monitor name Monitor ID 2018 2019 2020 2021 2022 2023 2024
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Avalon..................................................... 420030002 9.6 9.9 8.6 9.8 8.2 9.6 7.0
Lawrenceville.............................................. 420030008 9.0 9.0 7.7 9.0 7.6 9.7 7.2
Liberty.................................................... 420030064 11.5 12.2 9.8 11.8 11.0 12.0 9.0
South Fayette.............................................. 420030067 8.1 7.7 6.6 7.8 6.5 8.3 6.0
Harrison................................................... 420031008 9.3 8.6 7.3 8.2 7.1 8.9 6.6
North Braddock............................................. 420031301 10.2 9.9 9.0 10.7 8.5 10.7 8.4
Parkway East............................................... 420031376 10.3 10.8 9.0 10.4 8.5 9.6 6.9
Clairton................................................... 420033007 8.8 7.9 7.3 9.2 7.1 9.0 7.0
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Table 2--Design Values for the Allegheny County Area for the 2012 Annual PM2.5 NAAQS ([micro]g/m\3\) for
Monitoring Periods 2018-2020 Through 2022-2024
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Monitor name Monitor ID 2018-2020 2019-2021 2020-2022 2021-2023 2022-2024
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Avalon......................... 420030002 9.4 9.4 8.9 9.2 8.3
Lawrenceville.................. 420030008 8.5 8.5 8.1 8.7 8.1
Liberty........................ 420030064 11.1 11.2 10.9 11.6 10.6
South Fayette.................. 420030067 7.4 7.3 7.0 7.5 6.9
Harrison....................... 420031008 8.4 8.1 7.5 8.1 7.5
North Braddock................. 420031301 9.7 9.9 9.4 10.0 9.2
Parkway East................... 420031376 10.0 10.0 9.3 9.5 8.3
Clairton....................... 420033007 8.0 8.1 7.9 8.4 7.7
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[[Page 52322]]
B. The Area Has Met All Applicable Requirements Under Section 110 and
Part D of the CAA and Has a Fully Approved SIP Under Section 110(k)
In accordance with section 107(d)(3)(E)(v) of the CAA, Pennsylvania
must meet all the requirements applicable to the Allegheny County Area
under section 110 of the CAA (general SIP requirements) and part D of
Title I of the CAA (SIP requirements for nonattainment areas). Under
section 107(d)(3)(E)(ii) of the CAA, Pennsylvania's SIP revisions for
the 2012 annual PM<INF>2.5</INF> NAAQS for the Allegheny County Area
must be fully approved under section 110(k) of the CAA. Section 110(k)
of the CAA sets out the requirements for the EPA's actions on SIP
revision submittals. The September 4, 1992 Calcagni memorandum
describes EPA's interpretation of CAA section 107(d)(3)(E) with respect
to the timing of applicable requirements. Under this interpretation, to
qualify for redesignation, states requesting redesignation to
attainment must meet only the relevant CAA requirements that come due
prior to the submittal of a complete redesignation request. See also
Shapiro memorandum, September 17, 1993, and 60 FR 12459, 12465 and
12466, (March 7, 1995) (redesignation of Detroit-Ann Arbor). Applicable
requirements of the CAA that come due subsequent to the area's
submittal of a complete redesignation request remain applicable until a
redesignation is approved but are not required as a prerequisite to
redesignation. See CAA section 175A(c). Sierra Club v. EPA, 375 F .3d
537 (7th Cir. 2004). See also 68 FR 25418, 25424 and 25427 (May 12,
2003) (redesignation of the St. Louis/East St. Louis area to attainment
of the 1-hour ozone NAAQS). In the case of the Allegheny County Area,
the base year emissions inventory was due prior to Pennsylvania's
submittal of the complete redesignation request for the Allegheny
County Area. Therefore, the base year inventory is an applicable
requirement. The attainment plan, including RACM/RACT, and contingency
measures for failure to attain or meet RFP, were also due prior to
Pennsylvania's submittal of a complete redesignation request for the
Allegheny County Area. However, as referenced previously and described
in detail later in this rulemaking, a clean data determination for the
Allegheny County Area suspended these requirements for as long as the
Allegheny County Area continues to meet the 2012 annual
PM<INF>2.5</INF> NAAQS. When the Allegheny County Area is redesignated
to attainment, these requirements are permanently discharged.
a. Section 110 General SIP Requirements
Section 110(a)(2) of title I of the CAA delineates the general
requirements for a SIP, which include enforceable emissions limitations
and other control measures, means, or techniques, provisions for the
establishment and operation of appropriate devices necessary to collect
data on ambient air quality, and programs to enforce the limitations.
The general SIP elements and requirements set forth in CAA section
110(a)(2), which are commonly referred to as ``infrastructure SIPs,''
include, but are not limited to, the following: (1) submittal of a SIP
that has been adopted by the state after reasonable public notice and
hearing; (2) provisions for establishment and operation of appropriate
procedures needed to monitor ambient air quality; (3) implementation of
a minor source permit program and provisions for the implementation of
part C requirements (PSD); (4) provisions for the implementation of
part D requirements for nonattainment new source review (referred to as
``part D NNSR,'' ``NNSR,'' ``nonattainment NSR,'' or ``NSR'') permit
programs; (5) provisions for air pollution modeling; and (6) provisions
for public and local agency participation in planning and emission
control rule development.
CAA section 110(a)(2)(D) requires that SIPs contain certain
measures to prevent sources in a state from significantly contributing
to air quality problems in another state; the portion of a state's SIP
that include these measures is known as an interstate transport SIP.
However, these CAA section 110(a)(2)(D) requirements apply to a state
and are not linked with a particular nonattainment area's designation
and classification in that state. The interstate transport SIP
submittal requirements, where applicable, continue to apply to a state
regardless of the designation of any one area in the state. Thus, the
EPA has determined that these requirements are not applicable
requirements for purposes of redesignation. Instead, the EPA has
determined that the requirements linked with a particular nonattainment
area's designation and classifications are the relevant measures, i.e.,
the requirements that must be met for the EPA to redesignate an area.
In addition, the EPA has determined that the other CAA section
110(a)(2) elements not connected with nonattainment plan submissions
and not linked with an area's attainment status are not applicable
requirements for purposes of redesignation because the area will still
be subject to these requirements after it is redesignated. The EPA
concludes that the CAA section 110(a)(2) and part D requirements, which
are linked with a particular area's designation and classification, are
the relevant measures to evaluate in reviewing a redesignation request,
and that CAA section 110(a)(2) elements not linked to the area's
nonattainment status are not applicable for purposes of redesignation.
The EPA has applied this interpretation consistently in many
redesignations.\7\
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\7\ See, e.g., 81 FR 4420 (July 17, 2006) (final redesignation
for the Sullivan County, Tennessee area); 79 FR 43655 (July 28,
2014) (final redesignation for Bellefontaine, Ohio lead
nonattainment area); 61 FR 53174 through 53176 (October 10, 1996)
and 62 FR 24826 (May 7 1997) (proposed and final redesignation of
Reading, Pennsylvania ozone nonattainment area); 61 FR 20458 (May 7
1996) (final redesignation for Cleveland-Akron Lorain, Ohio ozone
nonattainment area); 60 FR 62748 (December 7, 1995) (final
redesignation of Tampa, Florida ozone nonattainment area); See also
65 FR 37879, 37890, (June 19, 2000) (discussing this issue in final
redesignation of Cincinnati, Ohio 1-hour ozone nonattainment area);
and 66 FR 50399 (October 19, 2001) (final redesignation of
Pittsburgh, Pennsylvania 1-hour ozone nonattainment area).
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The EPA has reviewed the Pennsylvania SIP and has concluded that it
meets the general SIP requirements under section 110(a)(2) of the CAA
to the extent they are applicable for purposes of redesignation. The
EPA has previously approved provisions of Pennsylvania's SIP addressing
CAA section 110(a)(2) requirements, including provisions addressing
PM<INF>2.5</INF>.\8\ These requirements are, however, statewide
requirements that are not linked to the PM<INF>2.5</INF> nonattainment
status of the Allegheny County Area. Therefore, the EPA proposes to
determine that Pennsylvania has met all general SIP requirements for
the Allegheny County Area that are applicable for purposes of
redesignation under section 110 of the CAA.
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\8\ See 80 FR 26461 (May 8, 2015) (approving infrastructure SIP
submittal for the 2012 PM<INF>2.5</INF> NAAQS).
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b. Part D Requirements
On August 24, 2016 (81 FR 58010), EPA promulgated the Fine
Particulate Matter National Ambient Air Quality Standards; State
Implementation Plan Requirements rule.\9\ This rule implements the
requirements of part D of title I of the CAA for areas designated
nonattainment for any PM<INF>2.5</INF> NAAQS. Subparts 1 and 4 of part
D, title 1 of the
[[Page 52323]]
CAA contain air quality planning requirements for PM<INF>2.5</INF>
nonattainment areas. Subpart 1 contains general requirements for all
nonattainment areas of any pollutant, including PM<INF>2.5</INF>,
governed by a NAAQS. Subpart 1 requirements include, among other
things, provisions for RACM, RFP, emissions inventories, contingency
measures, transportation conformity and general conformity. Subpart 4
contains specific planning and scheduling requirements for
PM<INF>2.5</INF> nonattainment areas. The requirements in CAA section
189(a), (c), (e) apply specifically to Moderate PM<INF>2.5</INF>
nonattainment areas and include an approved permit program for
construction of new and modified major stationary sources, provisions
for RACM, an attainment demonstration, quantitative milestones
demonstrating RFP toward attainment by the applicable attainment date,
and provisions to ensure that the control requirements applicable to
major stationary sources of PM<INF>2.5</INF> also apply to
PM<INF>2.5</INF> precursors, except where the Administrator has
determined that such sources do not contribute significantly to
PM<INF>2.5</INF> levels that exceed the NAAQS in the area. The
applicability of these requirements to this action are addressed in the
following sections.
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\9\ See 81 FR 58010 (August 24, 2016). See also 40 CFR part 51,
subpart Z.
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c. Subpart 1 Requirements
Subpart 1 sets forth the basic nonattainment plan requirements
applicable to PM<INF>2.5</INF> nonattainment areas. Under CAA section
172, states with nonattainment areas must submit plans providing for
timely attainment and must meet a variety of other requirements. The
EPA's longstanding interpretation of the nonattainment planning
requirements of CAA section 172 is that once an area is attaining the
NAAQS, those requirements are not ``applicable'' for purposes of CAA
section 107(d)(3)(E)(ii) and therefore need not be approved into the
SIP before the EPA can redesignate the area. In the 1992 General
Preamble for Implementation of Title I, the EPA set forth its
interpretation of applicable requirements for purposes of evaluating
redesignation requests when an area is attaining a standard.\10\ The
EPA noted that the requirements for RFP and other measures designed to
provide for attainment do not apply in evaluating redesignation
requests because those nonattainment planning requirements ``have no
meaning'' for an area that has already attained the standard.\11\ This
interpretation was also set forth in the 1992 Calcagni Memorandum. The
EPA's understanding of CAA section 172 also forms the basis of its
Clean Data Policy, which was articulated with regard to
PM<INF>2.5</INF> in 40 CFR 51.1015(a), and suspends a state's
obligation to submit most of the attainment planning requirements that
would otherwise apply, including an attainment demonstration and
planning SIPs to provide for RFP, RACM, and contingency measures under
CAA section 172(c)(9).\12\ Courts have upheld the EPA's interpretation
of CAA section 172(c)(1)'s ``reasonably available'' control measures
and control technology as meaning only those controls that advance
attainment, which precludes the need to require additional measures
where an area is already attaining.\13\
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\10\ See 57 FR 13498, 13564 (April 16, 1992).
\11\ Id.
\12\ This regulation was promulgated as part of the 1997
PM<INF>2.5</INF> NAAQS implementation rule that was subsequently
challenged and remanded in NRDC v. EPA, 706 F.3d 428 (D.C. Cir.
2013). However, the Clean Data Policy portion of the implementation
rule was not at issue in that case.
\13\ See NRDC v. EPA, 571 F.3d 1245, 1252 (D.C. Cir. 2009);
Sierra Club v. EPA, 294 F.3d 155, 162 (D.C. Cir. 2002); Sierra Club
v. EPA, 314 F.3d 735, 744 (5th Cir. 2002).
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As stated previously, the EPA determined that the Allegheny County
Area had clean data for the 2012 PM<INF>2.5</INF> NAAQS and attained
the NAAQS by the applicable attainment date.\14\ Furthermore, as shown
in section IV.A of this document, the Allegheny County Area continues
to attain the 2012 annual PM<INF>2.5</INF> NAAQS. Therefore, because
attainment has been reached for the 2012 annual PM<INF>2.5</INF> NAAQS
in the Allegheny County Area, no additional measures are needed to
provide for attainment of these standards, and the CAA section
172(c)(1) requirements for an attainment demonstration and RACM are no
longer considered to be applicable for purposes of redesignation as
long as the Allegheny County Area continues to attain each standard
until redesignation.\15\ Nonetheless, as stated previously, the EPA has
approved most elements of Pennsylvania's Allegheny County
PM<INF>2.5</INF> Attainment Plan, including an attainment demonstration
and RACM analysis.\16\
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\14\ See 87 FR 14799 (March 16, 2022) (Allegheny County Area's
clean data determination for the 2012 annual PM<INF>2.5</INF> NAAQS)
and 88 FR 32117 (May 19, 2023) (Allegheny County Area's
determination of attainment by the attainment date for the 2012
annual PM<INF>2.5</INF> NAAQS).
\15\ Id.
\16\ See 86 FR 26388 (May 14, 2021).
---------------------------------------------------------------------------
Section 172(c)(2)'s of the CAA requirement that nonattainment plans
contain provisions promoting reasonable further progress toward
attainment is also not relevant for purposes of redesignation because
the EPA has determined that the Allegheny County Area has monitored
attainment of the 2012 annual PM<INF>2.5</INF> NAAQS. As stated
previously, the EPA has approved most elements of Pennsylvania's
Allegheny County PM<INF>2.5</INF> Attainment Plan, including the RFP
demonstration as meeting the requirements of CAA section 172(c)(2).\17\
In addition, because the Allegheny County Area has attained the 2012
annual PM<INF>2.5</INF> NAAQS and is no longer subject to an RFP
requirement, the requirement to submit the CAA section 172(c)(9)
contingency measures is not applicable for purposes of redesignation.
Section 172(c)(6) of the CAA requires the SIP to contain control
measures necessary to provide for attainment of the NAAQS. Because
attainment has been reached, no additional measures are needed to
provide for attainment.
---------------------------------------------------------------------------
\17\ Id.
---------------------------------------------------------------------------
The requirement under section 172(c)(3) of the CAA was not
suspended by the EPA's clean data determination for the 2012 annual
PM<INF>2.5</INF> NAAQS. Section 172(c)(3) of the CAA requires
submission and approval of a comprehensive, accurate, and current
inventory of actual emissions. For purposes of the PM<INF>2.5</INF>
NAAQS, this emissions inventory should address not only direct
emissions of PM<INF>2.5</INF>, but also emissions of all precursors
with the potential to participate in PM<INF>2.5</INF> formation, i.e.,
SO<INF>2</INF>, NO<INF>X</INF>, VOC and NH<INF>3</INF>. To satisfy the
CAA section 172(c)(3) requirement, on May 14, 2021 (86 FR 26388), the
EPA approved the 2011 base year emissions inventory for the 2012 annual
PM<INF>2.5</INF> NAAQS for the Allegheny County Area.
Section 172(c)(4) of the CAA requires the identification and
quantification of allowable emissions for major new and modified
stationary sources in an area, and CAA section 172(c)(5) requires
source permits for the construction and operation of new and modified
major stationary sources anywhere in the nonattainment area. The EPA
has determined that, since PSD requirements will apply after
redesignation, areas being redesignated need not comply with the
requirement that a nonattainment NSR program be approved prior to
redesignation, provided that the area demonstrates maintenance of the
NAAQS without a nonattainment NSR program. A more detailed rationale
for this view is described in a memorandum from Mary Nichols, Assistant
Administrator for Air and Radiation, dated October 14, 1994, entitled,
``Part D New Source Review Requirements for Areas Requesting
Redesignation to Attainment.'' Nevertheless, Pennsylvania currently
[[Page 52324]]
has an approved NSR program codified in Pennsylvania's regulations at
25 Pa. Code Chapter 127.201, et. seq.\18\ Pennsylvania's regulations
were incorporated by reference into ACHD's nonattainment new source
review regulations for Allegheny County on March 30, 2015 (80 FR
16568). A revision to the NNSR regulations for Allegheny County for the
2012 annual PM<INF>2.5</INF> NAAQS was approved into the Pennsylvania
SIP on June 15, 2020 (85 FR 36161). However, ACHD's PSD program in
section 2102.07 of Article XXI of Allegheny County Health Department's
Rules and Regulations for Air Pollution Control for PM<INF>2.5</INF>
will become effective in the Allegheny County Area upon redesignation
to attainment. Section 2102.07 of Article XXI adopted in its entirety,
and incorporated by reference, the PSD requirements of 40 CFR part
52.\19\ The EPA also previously approved Pennsylvania's PSD program
required under section 110 of the CAA.\20\
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\18\ See 77 FR 41276 (July 13, 2012) (approving NSR program into
the SIP).
\19\ See 78 FR 13493 (February 28, 2013) (most recent PSD
revision for ACHD's portion of the Pennsylvania SIP).
\20\ See 49 FR 33127 (August 21, 1984).
---------------------------------------------------------------------------
Section 172(c)(7) of the CAA requires the SIP to meet the
applicable provisions of CAA section 110(a)(2). As noted previously,
the EPA believes the Pennsylvania SIP meets the requirements of CAA
section 110(a)(2) that are applicable for purposes of redesignation,
which have been identified as CAA section 172(c)(3) through (5).
Section 175A of the CAA requires a state seeking redesignation to
attainment to submit a SIP revision to provide for the maintenance of
the NAAQS in the area ``for at least 10 years after the
redesignation.'' On July 24, 2025 (90 FR 34770), the EPA approved, as a
revision to the Pennsylvania SIP and meeting the requirements of CAA
section 175A, a maintenance plan that demonstrates maintenance of the
2012 annual PM<INF>2.5</INF> NAAQS through 2035 in the Allegheny County
Area.
Section 176(c) of the CAA requires states to establish criteria and
procedures to ensure that federally supported or funded projects
conform to the air quality planning goals in the applicable SIP. The
requirement to determine conformity applies to transportation plans,
programs, and projects that are developed, funded, or approved under
title 23 of the United States Code (U.S.C.) and the Federal Transit Act
(transportation conformity) as well as to all other federally supported
or funded projects (general conformity). State transportation
conformity SIP revisions must be consistent with Federal conformity
regulations relating to consultation, enforcement, and enforceability
which the EPA promulgated pursuant to its authority under the CAA. The
EPA interprets the conformity SIP requirements as not applying for
purposes of evaluating a redesignation request under CAA section 107(d)
because state conformity rules are still required after redesignation,
and Federal conformity rules apply where state rules have not been
approved.\21\ Nonetheless, the EPA approved Pennsylvania's
transportation conformity SIP requirements on April 29, 2009 (74 FR
19451).
---------------------------------------------------------------------------
\21\ See Wall v. EPA, 265 F. 3d 426 (6th Cir. 2001) (upholding
this interpretation) and 60 FR 62748 (December 7, 1995) (discussing
Tampa, Florida).
---------------------------------------------------------------------------
The EPA concludes that Pennsylvania has met the requirements of
subpart 1 of part D relevant for redesignation. Specifically, pursuant
to section 110(k) of the CAA, the EPA has approved Pennsylvania's 2011
base year inventory and maintenance plan through 2035 for the Allegheny
County Area into the Pennsylvania SIP.
d. Subpart 4 Requirements
A January 4, 2013, U.S. Court of Appeals for the District of
Columbia Circuit decision \22\ stated that the EPA must implement
PM<INF>2.5</INF> NAAQS pursuant to subpart 4 of part D of the CAA,
which contains provisions specifically concerning PM<INF>10</INF>
nonattainment areas. Section 189 in subpart 4 of the CAA sets out the
requirements for PM<INF>10</INF> and PM<INF>2.5</INF> nonattainment
areas. Section 189(a) of the CAA contains the SIP revision requirements
for moderate PM<INF>10</INF> and PM<INF>2.5</INF> nonattainment areas,
including the requirements for the state to submit an attainment
demonstration, RACM (including (RACT) for stationary sources). Section
189(c) of the CAA contains requirements for RFP, quantitative
milestones and quantitative milestone reports.
---------------------------------------------------------------------------
\22\ Natural Resources Defense Council v. EPA, 706 F. 3d 428
(D.C. Cir. 2013).
---------------------------------------------------------------------------
As with the requirements of CAA section 172(c), explained
previously in this document, the requirements of CAA section 189(a) and
(c) are no longer considered to be applicable for purposes of
redesignation as long as the Area continues to attain the standard.
Because attainment has been reached, no additional measures are needed
to provide for attainment. The EPA's clean data determination for the
Allegheny County Area suspended the requirements for the state to
submit an attainment demonstration, RACM and RACT, RFP, quantitative
milestones, and quantitative milestone reports until such time as the
Area is redesignated to attainment, after which such requirements are
permanently discharged.\23\ Nonetheless, as stated previously, the EPA
has approved most elements of Pennsylvania's Allegheny County
PM<INF>2.5</INF> Attainment Plan, including an attainment demonstration
(CAA section 189(a)(1)(B)), RACM analysis (CAA section 189(a)(1)(C)),
quantitative milestones to ensure timely attainment (CAA section
189(c)), and a particulate matter precursor demonstration (CAA section
189(e)).\24\ Therefore, the EPA concludes that ACHD has met the
requirements of subpart 4 of part D relevant for redesignation.
---------------------------------------------------------------------------
\23\ See 87 FR 14799 (March 16, 2022) (Allegheny County Area's
clean data determination for the 2012 annual PM<INF>2.5</INF>
NAAQS).
\24\ See 86 FR 26388 (May 14, 2021).
---------------------------------------------------------------------------
For these reasons, the EPA proposes to find that ACHD has satisfied
all applicable requirements for purposes of redesignation of the
Allegheny County Area under section 110 and part D of the CAA.
Specifically, pursuant to section 110(k) of the CAA, the EPA has
approved Pennsylvania's 2011 base year inventory and maintenance plan
through 2035 for the Allegheny County Area into the Pennsylvania SIP.
e. The Allegheny County Area Has a Fully Approved Applicable SIP Under
Section 110(k) of the CAA
At various times, ACHD and PADEP have submitted, and the EPA has
approved, provisions addressing the various SIP elements applicable for
the 2012 annual PM<INF>2.5</INF> NAAQS. Indicated above, the EPA
believes that the section 110 of the CAA elements not connected with
nonattainment plan submissions and not linked to an area's
nonattainment status are not applicable requirements for purposes of
redesignation. The EPA may rely on prior SIP approvals in approving a
redesignation request (see the Calcagni Memo at page 3; Southwestern
Pennsylvania Growth Alliance v. Browner, 144 F.3d 984, 989-990 (6th
Cir. 1998); Wall v. EPA, 265 F.3d 426), plus any additional measures it
may approve in conjunction with a redesignation action (see 68 FR 25426
(May 12, 2003) and citations therein).
As discussed previously, the EPA has fully approved Pennsylvania's
SIP for the Allegheny County Area under section 110(k) for all
requirements applicable under CAA section 110 general SIP requirements
and subparts 1
[[Page 52325]]
and 4 of part D for purposes of redesignation to attainment for the
2012 annual PM<INF>2.5</INF> NAAQS. The EPA has previously approved
Pennsylvania's 2011 base year emissions inventory for the Allegheny
County Area as meeting the requirement of section 172(c)(3) of the
CAA.\25\ The EPA has also previously approved Pennsylvania's
maintenance plan for the Allegheny County Area for the 2012
PM<INF>2.5</INF> NAAQS through 2035 as meeting the requirement of
section 175A of the CAA.\26\ Lastly, the EPA has previously approved
Pennsylvania's and ACHD's PSD programs required under section 110 of
the CAA.\27\ The EPA has determined that there are no outstanding SIP
elements required for the Allegheny County Area for purposes of
redesignation to attainment for the 2012 annual PM<INF>2.5</INF> NAAQS.
No Allegheny County Area SIP provisions are currently disapproved,
conditionally approved, or partially approved. Therefore, the
Administrator has fully approved the applicable requirements for the
Allegheny County Area under CAA section 110(k) in accordance with CAA
section 107(d)(3)(E)(ii).
---------------------------------------------------------------------------
\25\ See 86 FR 26388 (May 14, 2021).
\26\ See 90 FR 34770 (July 24, 2025).
\27\ See 49 FR 33127 (August 21, 1984) (Pennsylvania PSD
program) and 78 FR 13493 (February 28, 2013) (most recent PSD
revision for ACHD's portion of the Pennsylvania SIP).
---------------------------------------------------------------------------
C. Permanent and Enforceable Reductions in Emissions
For redesignating a nonattainment area to attainment, CAA section
107(d)(3)(E)(iii) requires the EPA to determine that the air quality
improvement in the area is due to permanent and enforceable reductions
in emissions resulting from implementation of the SIP and applicable
Federal air pollution control regulations and other permanent and
enforceable reductions. For the 2012 annual PM<INF>2.5</INF> NAAQS,
ACHD has calculated the change in emissions between the 2011 base year
and a 2017 control year for the Allegheny County Area. ACHD selected
2017 as the control year as it is the year selected for the attainment
emission inventory in the maintenance plan.\28\ The attainment
inventory identifies the level of emissions in an area that is
sufficient to attain the NAAQS. A summary of the emissions reductions
in tons per year (tpy) of PM<INF>2.5</INF>, NO<INF>X</INF>,
SO<INF>2</INF>, VOC, and NH<INF>3</INF> from the base year to the
control year in the Allegheny County Area, provided by ACHD, is shown
in tables 3 and 4, in this document.\29\
---------------------------------------------------------------------------
\28\ See 90 FR 34770 (July 24, 2025).
\29\ See Id. for further information regarding the emission
inventory methodology and emission data by category totals for the
Allegheny County Area.
Table 3--Allegheny County Area Emissions Reductions, 2012 Annual PM2.5 NAAQS
[tons/year]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Allegheny County Area Totals (2012 Annual PM2.5 NAAQS) PM2.5 PM2.5
PM2.5 (filterable) (condensable) PM10 SO2 NOX VOC NH3
--------------------------------------------------------------------------------------------------------------------------------------------------------
2011 Base Year........................................ 5,829 4,185 1,644 9,061 15,080 35,460 29,972 1,141
2017 Control Year..................................... 4,437 3,207 1,230 6,728 5,033 23,273 25,383 1,238
Reduction, Base to Control Year....................... -1,392 -978 -414 -2,333 -10,047 -12,187 -4,589 97
Percent Change........................................ -24% -23% -25% -26% -67% -34% -15% 9%
--------------------------------------------------------------------------------------------------------------------------------------------------------
From the 2011 base year to the 2017 control year for the 2012
annual PM<INF>2.5</INF> NAAQS, overall PM<INF>2.5</INF> emissions were
reduced by 24%. NH<INF>3</INF> was the only pollutant that did not show
a reduction in the Area. However, NH<INF>3</INF> was found to be an
insignificant precursor for attainment in the Allegheny County
Area.\30\ The reduction in emissions and the corresponding improvement
in air quality in the Allegheny County Area from 2011 to 2017 for the
2012 annual PM<INF>2.5</INF> NAAQS can be attributed to a number of
control measures that have been implemented in the Allegheny County
Area and contributing areas in recent years.
---------------------------------------------------------------------------
\30\ See EPA's proposed approval of certain elements of
Allegheny County's 2012 PM<INF>2.5</INF> attainment plan, including
the precursor demonstration discussion, at 85 FR 35852 (May 14,
2021).
---------------------------------------------------------------------------
ACHD identified implemented source controls at the United States
Steel Corporation (USS) Mon Valley Works (MVW) Clairton Plant that have
contributed to reductions of PM<INF>2.5</INF> levels in the Allegheny
County Area between 2011 and 2017. Some of these controls were required
by consent order and agreements entered into between ACHD and USS in
2007 and in 2008 (later amended in 2010 and 2011). The USS Clairton
Plant requires permits to operate (operating permit) and to install new
equipment or expand operations (installation permits). These consent
order and agreements were incorporated by reference into installation
permits for the C Coke Battery (IP #0052-I011) and Quench Towers 5A and
7A (IP #0052-I014a). The USS Clairton Plant's title V operating permit
(OP #0052) incorporates conditions from the installation permits and
other applicable regulations. These permits are federally enforceable
under 40 CFR 52.2020. Controls specific to the USS Clairton Plant that
contributed to reduction in PM<INF>2.5</INF> levels for the 2012 annual
PM<INF>2.5</INF> NAAQS are as follows:
<bullet> 25 heating walls for Coke Battery 19 were replaced in
2012.
<bullet> The title V permit (OP #0052) issued in 2012 included
baffle washing and maintenance requirements at all quench towers.\31\
---------------------------------------------------------------------------
\31\ These source control requirements were also approved into
the SIP as part of source specific RACT controls for the 2008 8-hour
ozone NAAQS (86 FR 58223, October 21, 2021), which requires quench
towers at the USS Clairton Plant to comply with the quench tower
work practice standards, and operation and maintenance requirements
of NESHAP 40 CFR part 63, subpart CCCCC, including daily baffle
washing.
---------------------------------------------------------------------------
<bullet> New low-emission Quench Towers 5A and 7A were installed
for Coke Batteries 13-15 and 19-20, respectively, in 2013.
<bullet> A new Screening Station #4 was installed as a replacement
to Screening Station #3 in 2013.
In addition to the controls implemented at the USS Clairton Plant,
ACHD identified several implemented controls at other major point
source facilities in Allegheny County during the timeframe of 2011 to
2017 that contributed to reduction of PM<INF>2.5</INF> and precursor
emissions throughout Allegheny County.
<bullet> The GenOn Cheswick power plant installed a flue gas
desulfurization (FGD) system in 2010 (IP #0054-I004), with full system
operation started in mid-2011.\32\
---------------------------------------------------------------------------
\32\ ACHD notes this source has now permanently ceased
operations.
---------------------------------------------------------------------------
<bullet> In 2013, The ATI Flat Rolled Products (Allegheny Ludlum)
specialty steel-making facility in Harrison Township installed a new
Hot Rolling Processing Facility (HRPF) at the plant (IP #0062-I008),
along with a
[[Page 52326]]
consolidation of melt shops in 2011 (IP #0062-I007).
<bullet> The McConway & Torley steel foundry completed several
modifications since 2011, including a new electric arc furnace, new
baghouses, and new ladle preheater burners (IP #0275-I007, I008, I011,
I013).
<bullet> The Bay Valley food manufacturing facility permanently
switched from coal to natural gas fuel for all boilers in 2015 (IP
#0079-I005).\33\
---------------------------------------------------------------------------
\33\ ACHD notes this source has now permanently ceased
operations.
---------------------------------------------------------------------------
ACHD states that when a source permanently ceases all operations,
the corresponding operating permit becomes inactive, either by
termination or expiration. After a permit is inactive, any future
operation at the source property requires a new permit application
along with new source review (NSR). ACHD notes that enforcement staff
conduct follow-up inspections at these sources to ensure continued
inactivity and/or demolition at these properties. ACHD identified the
following major point source facilities in Allegheny County that have
permanently retired during the timeframe of 2011 to 2017, with their
permits terminated or expired:
<bullet> ACN container facility (ceased operations in 2013);
<bullet> Guardian glass plant (ceased operations in 2015); and
<bullet> Shenango coke plant (ceased operations in 2016).
ACHD identified Federal and State rules and regulations that have
contributed to PM<INF>2.5</INF> and precursor emission reductions
throughout Allegheny County during the 2011 to 2017 timeframe,
including:
<bullet> Greenhouse Gas Emissions and Fuel Efficiency Standards for
Medium- and Heavy-Duty Engines and Vehicles (Phase 1); \34\
---------------------------------------------------------------------------
\34\ See 76 FR 57106 (September 15, 2011).
---------------------------------------------------------------------------
<bullet> Final Rule for Model Year 2012-2016 Light-Duty Vehicle
Greenhouse Gas Emission Standards and Corporate Average Fuel Economy
Standards; \35\
---------------------------------------------------------------------------
\35\ See 75 FR 25324 (May 7, 2010).
---------------------------------------------------------------------------
<bullet> Standards of Performance for New Residential Wood Heaters,
New Residential Hydronic Heaters and Forced-Air Furnaces; \36\
---------------------------------------------------------------------------
\36\ See 80 FR 13672 (March 16, 2015).
---------------------------------------------------------------------------
<bullet> National Emission Standards for Hazardous Air Pollutants
for Area Sources: Industrial, Commercial, and Institutional Boilers;
\37\
---------------------------------------------------------------------------
\37\ See 78 FR 7488 (February 1, 2013).
---------------------------------------------------------------------------
<bullet> National Emission Standards for Hazardous Air Pollutants
for Reciprocating Internal Combustion Engines; New Source Performance
Standards for Stationary Internal Combustion Engines; \38\
---------------------------------------------------------------------------
\38\ See 78 FR 6674 (January 30, 2013).
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<bullet> Commercial and Industrial Solid Waste Incineration Units:
Reconsideration and Final Amendments; \39\
---------------------------------------------------------------------------
\39\ See 78 FR 9112 (February 7, 2013).
---------------------------------------------------------------------------
<bullet> Control of Air Pollution from Motor Vehicles: Tier 3 Motor
Vehicle Emission and Fuel Standards; \40\
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\40\ See 79 FR 23414 (April 28, 2014).
---------------------------------------------------------------------------
<bullet> Cross-State Air Pollution Rule (CSAPR) Allowance
Allocations, Groups 1 and 2; \41\
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\41\ EPA CSAPR: <a href="http://www.epa.gov/Cross-State-Air-Pollution/csapr-allowance-allocations">www.epa.gov/Cross-State-Air-Pollution/csapr-allowance-allocations</a>.
---------------------------------------------------------------------------
<bullet> PA Adhesives and Sealants Rule; \42\ and
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\42\ See 77 FR 59090 (September 26, 2012).
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<bullet> PA Fuel Oil Sulfur Limits Rule.\43\
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\43\ See 79 FR 39330 (July 10, 2014).
---------------------------------------------------------------------------
In addition, ACHD provided an analysis to demonstrate that the
improvement in air quality for the Allegheny County Area was not due to
unusually favorable meteorology. The analysis was based on 14 years of
meteorological data collected at the Liberty monitor (ID #420030064)
and included frequency of temperature inversions, average temperature,
and total precipitation. The Liberty site has historically been the
highest-concentration PM<INF>2.5</INF> site within the Allegheny County
Area. ACHD identified that temperature inversions correlate with
monitored PM<INF>2.5</INF> concentrations at the Liberty monitor, and
that a higher frequency of temperature inversions coincide with
relatively higher measured PM<INF>2.5</INF> concentrations. While
variations in PM<INF>2.5</INF> concentrations from year-to-year
correlate with the frequency of temperature inversions, ACHD identified
that both annual weighted mean and 24-hour 98th percentile
concentrations at the Liberty monitor have declined throughout the
timeframe while the average frequency of inversions remained similar
throughout the period, indicating that the reductions are due to
emissions control and not unusually favorable meteorology due to
temperature inversions.
ACHD identified that temperature and precipitation can also affect
formation of PM<INF>2.5</INF>. Higher temperatures are typically
associated with higher concentrations of PM<INF>2.5</INF> since higher
temperature can be more favorable for PM<INF>2.5</INF> precursors. ACHD
notes that 2024 was the warmest year recorded in Allegheny County
dating back to 1895, and 2012 and 2023 were also in the top five
warmest. However, both the short-term and long-term PM<INF>2.5</INF>
concentrations decreased over the 2011 to 2024 timeframe, indicating
reductions in PM<INF>2.5</INF> concentrations are not due to favorable
temperatures. ACHD additionally determined that, while years 2018 and
2019 may have seen a reduction in PM<INF>2.5</INF> due to wet
deposition, the measured overall decrease in PM<INF>2.5</INF> over the
2011 to 2024 timeframe was not likely due to favorable precipitation.
Based upon the previously listed actions by ACHD, the EPA finds
that the improvement in air quality in the Allegheny County Area is the
result of permanent and enforceable emissions reductions, satisfying
CAA section 107(d)(3)(E)(iii).
D. Fully Approved Maintenance Plan
As one of the criteria for redesignation to attainment, section
107(d)(3)(E)(iv) of the CAA requires the EPA to determine that the area
has a fully approved maintenance plan pursuant to section 175A of the
CAA. Section 175A of the CAA sets forth the elements of a maintenance
plan for areas seeking redesignation from nonattainment to attainment.
Under CAA section 175A, the maintenance plan must demonstrate continued
attainment of the NAAQS for at least 10 years after the Administrator
approves a redesignation to attainment. Eight years after the
redesignation, the state must submit a revised maintenance plan which
demonstrates that attainment of the NAAQS will continue for an
additional 10 years beyond the initial 10-year maintenance period. To
address the possibility of future NAAQS violations, the maintenance
plan must contain contingency measures, as the EPA deems necessary, to
assure prompt correction of the future NAAQS violation. The Calcagni
memorandum provides further guidance on the content of a maintenance
plan, explaining that a maintenance plan should address five elements:
(1) an attainment emission inventory; (2) a maintenance demonstration;
(3) a commitment for continued air quality monitoring; (4) a process
for verification of continued attainment; and (5) a contingency plan.
In conjunction with the request to redesignate the Liberty-
Clairton, Pennsylvania nonattainment area (Liberty-Clairton Area) to
attainment for the 1997 annual and 2006 24-hour PM<INF>2.5</INF> NAAQS,
Pennsylvania submitted, as a revision to the Pennsylvania SIP, a plan
to provide maintenance of the 2012 annual PM<INF>2.5</INF> NAAQS for
the Allegheny County Area through 2035. On July 24, 2025 (90 FR 34770),
the EPA approved Pennsylvania's maintenance plan for the
[[Page 52327]]
Allegheny County Area as a revision to Pennsylvania's SIP. Therefore,
the EPA finds that Pennsylvania has satisfied the maintenance plan
requirement of CAA section 107(d)(3)(E)(iv) for redesignation to
attainment of the Allegheny County Area for the 2012 annual
PM<INF>2.5</INF> NAAQS.
V. Proposed Actions
The EPA is proposing to approve Pennsylvania's September 4, 2025
request to redesignate the Allegheny County Area from nonattainment to
attainment for the 2012 annual PM<INF>2.5</INF> NAAQS. The EPA has
evaluated Pennsylvania's redesignation request and determined that the
Allegheny County Area has met the redesignation criteria set forth in
section 107(d)(3)(E) of the CAA. The monitoring data demonstrates that
the Allegheny County Area attained, as determined by the EPA in a prior
rulemaking, and for reasons discussed herein, continues to attain the
NAAQS. Final approval of this redesignation request would change the
designation of the Allegheny County Area from nonattainment to
attainment for the 2012 annual PM<INF>2.5</INF> NAAQS. The EPA is
soliciting public comments on the issues discussed in this document.
These comments will be considered before taking final action.
VI. Statutory and Executive Order Reviews
Under the CAA, the redesignation of an area to attainment is an
action that affects the status of a geographical area and does not
impose any additional regulatory requirements on sources beyond those
required by state law. A redesignation to attainment does not in and of
itself impose any new requirements, but rather results in the
application of requirements contained in the CAA for areas that have
been redesignated to attainment. For that reason, this proposed action:
<bullet> Is not a significant regulatory action subject to review
by the Office of Management and Budget under Executive Orders 12866 (58
FR 51735, October 4, 1993);
<bullet> Executive Order 14192 (90 FR 9065, February 6, 2025) does
not apply because this action is exempt from review under Executive
Order 12866;
<bullet> Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
<bullet> Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
<bullet> Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
<bullet> Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
<bullet> Is not an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
<bullet> Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
<bullet> Is not subject to requirements of Section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the Clean Air Act;
In addition, this proposed redesignation of the Allegheny County
Area to attainment of the 2012 annual PM<INF>2.5</INF> NAAQS does not
have tribal implications as specified by Executive Order 13175 (65 FR
67249, November 9, 2000), because this action is not approved to apply
in Indian country located in the State, and the EPA notes that it will
not impose substantial direct costs on tribal governments or preempt
tribal law.
List of Subjects in 40 CFR Part 81
Environmental protection, Air pollution control, Carbon monoxide,
Intergovernmental relations, Lead, Nitrogen dioxide, Ozone, Particulate
matter, Reporting and recordkeeping requirements, Sulfur oxides,
Volatile organic compounds.
Amy Van Blarcom-Lackey,
Regional Administrator, Region III.
[FR Doc. 2025-20409 Filed 11-19-25; 8:45 am]
BILLING CODE 6560-50-P
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This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.