Air Plan Approval; Pennsylvania; Redesignation Request for the Allegheny County Area for the 2012 Annual Fine Particulate Matter Standard

ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 81</CFR> <DEPDOC>[EPA-R03-OAR-2025-1777; FRL-12985-01-R3]</DEPDOC> <SUBJECT>Air Plan Approval; Pennsylvania; Redesignation Request for the Allegheny County Area for the 2012 Annual Fine Particulate Matter Standard</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Environmental Protection Agency (EPA). <HD SOURCE="HED">ACTION:</HD> Proposed rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> 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 <E T="52">2.5</E> ) 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 <E T="52">2.5</E> 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). </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> Written comments must be received on or before December 22, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> Submit your comments, identified by Docket ID No. EPA-R03- OAR-2025-1777 at <E T="03">www.regulations.gov,</E> or via email to <E T="03">gordon.mike@epa.gov.</E> For comments submitted at <E T="03">Regulations.gov</E> , follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from <E T="03">Regulations.gov.</E> 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 ( <E T="03">i.e.,</E> on the web, cloud, or other file sharing system). For additional submission methods, please contact the person identified in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section. For the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit <E T="03">www.epa.gov/dockets/commenting-epa-dockets.</E> <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> 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 <E T="03">neiswinter.ian@epa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> Throughout this document, wherever “we,” “us,” or “our” are used, it is intended to refer to the EPA. <HD SOURCE="HD1">I. What action is the EPA proposing?</HD> 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  <SU>1</SU> <FTREF/> from nonattainment to attainment of the 2012 annual PM <E T="52">2.5</E> NAAQS. The EPA has already approved, as a revision to Pennsylvania's SIP, a maintenance plan that demonstrates maintenance of the 2012 annual PM <E T="52">2.5</E> NAAQS through 2035 in the Allegheny County Area. <E T="03">See</E> 90 FR 34770 (July 24, 2025). <FTNT> <SU>1</SU>  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. </FTNT> <HD SOURCE="HD1">II. Background</HD> Fine particulate pollution can be emitted directly from a source (primary PM <E T="52">2.5</E> ) or formed secondarily through chemical reactions in the atmosphere involving precursor pollutants emitted from a variety of sources. The main precursors of secondary PM <E T="52">2.5</E> are sulfur dioxide (SO <E T="52">2</E> ), nitrogen oxides (NO <E T="52">X</E> ), ammonia (NH <E T="52">3</E> ), and volatile organic compounds (VOCs). <SU>2</SU> <FTREF/> Sulfates are a type of secondary particulate formed from SO <E T="52">2</E> emissions from power plants and industrial facilities. Nitrates, another common type of secondary particulate, are formed from combustion emissions of NO <E T="52">X</E> from power plants, mobile sources, and other combustion sources. <FTNT> <SU>2</SU>   <E T="03">See</E> 81 FR 58010 (August 24, 2016). </FTNT> On January 15, 2013 (78 FR 3086), the EPA promulgated a revised primary annual PM <E T="52">2.5</E> NAAQS to provide increased protection of public health from fine particle pollution. In that action, the EPA strengthened the primary annual PM <E T="52">2.5</E> standard from 15.0 micrograms per cubic meter (µg/m <SU>3</SU> ) to 12.0 µg/m <SU>3</SU> , which is attained when the 3-year average of the annual arithmetic means does not exceed 12.0 µg/m <SU>3</SU> . On January 15, 2015 (80 FR 2206), the EPA published air quality designations for the 2012 annual PM <E T="52">2.5</E> 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 <E T="52">2.5</E> NAAQS. <E T="03">See</E> 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 <E T="52">2.5</E> 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 <E T="52">2.5</E> NAAQS for the Allegheny County Area (Allegheny County PM <E T="52">2.5</E> 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 <E T="52">2.5</E> NAAQS. <SU>3</SU> <FTREF/> On May 19, 2023 (88 FR 32117), the EPA determined that the Allegheny County Area had attained the 2012 annual PM <E T="52">2.5</E> NAAQS by the applicable attainment date based on certified air quality data from 2019-2021. <FTNT> <SU>3</SU>   <E T="03">See</E> 86 FR 26388 (May 14, 2021). </FTNT> 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 <E T="52">2.5</E> NAAQS through 2035 in the Allegheny County Area. <HD SOURCE="HD1">III. The EPA's Requirements for Redesignation to Attainment</HD> 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)  <SU>4</SU> <FTREF/> 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 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. <FTNT> <SU>4</SU>  See 57 FR 134 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 62k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━