2026-20468: Initial Air Quality Designations for the 2024 Revised Primary Annual Fine Particle (PM2.5) National Ambient Air Quality Standards (NAAQS)

Federal Register, Volume 91 Issue 192 (Tuesday, October 6, 2026) [Federal Register Volume 91, Number 192 (Tuesday, October 6, 2026)] [Proposed Rules] [Pages 63516-63519] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 2026-20468] ======================================================================= ----------------------------------------------------------------------- ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 81 [EPA-HQ-OAR-2024-0078; FRL-11650-03-OAR] RIN 2060-AW33 Initial Air Quality Designations for the 2024 Revised Primary Annual Fine Particle (PM2.5) National Ambient Air Quality Standards (NAAQS)

Agency

Environmental Protection Agency (EPA).

Action

Notice of availability; opportunity for public comment. -----------------------------------------------------------------------

Summary

The U.S. Environmental Protection Agency (EPA) is providing notice of the Agency's intended approach for area designations for the 2024 primary annual fine particulate matter (PM2.5) National Ambient Air Quality Standard (NAAQS) (the 2024 annual PM2.5 NAAQS) under Clean Air Act (CAA) section 107(d). Details regarding these designations, as well as the EPA's notifications to States, territories, and Tribes regarding their initial area designations are accessible via the Agency's website and public electronic docket. With this notice, the EPA is providing an opportunity for public comment on its intended approach for finalizing area designations during the comment period [[Page 63517]] specified in the DATES section. The EPA sent notifications directly to applicable States, territories, and Tribes regarding their initial area designations on or about October 2, 2026, and anticipates promulgating final designations consistent with CAA requirements.

Dates

Comments must be received on or before November 5, 2026.

Addresses

You may send comments, identified by Docket ID No. EPA-HQ- OAR-2024-0078, by any of the following methods: Federal eRulemaking Portal: https://www.regulations.gov (the EPA's preferred method). Follow the online instructions for submitting comments. Email: [email protected]. Include Docket ID No. EPA- HQ-OAR-2024-0078 in the subject line of the message. Mail: U.S. Environmental Protection Agency, EPA Docket Center, Office Air and Radiation Docket, Mail Code 28221T, 1200 Pennsylvania Avenue NW, Washington, DC 20460. Hand Delivery or Courier (by scheduled appointment only): EPA Docket Center, WJC West Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. The Docket Center's hours of operations are 8:30 a.m.-4:30 p.m., Monday-Friday (except Federal holidays). Instructions: All submissions received must include the Docket ID No. for this rulemaking. Comments received may be posted without change to https://www.regulations.gov, including any personal information provided. For detailed instructions on sending comments and additional information on the rulemaking process, see the SUPPLEMENTARY INFORMATION section of this document. For information on EPA Docket Center services, please visit us online at https://www.epa.gov/dockets.

For Further Information Contact

For information on this notice of data availability, contact Gabrielle Deabler, U.S. Environmental Protection Agency, Office of State Air Partnerships, Air Quality Planning Division, P.O. Box 12055, Mail Code: C541G, Research Triangle Park, NC 27709; telephone number: (919) 541-5766; email address: [email protected] or Andrew Leith, U.S. Environmental Protection Agency, Office of State Air Partnerships, Air Quality Planning Division, P.O. Box 12055, Mail Code: C541D, Research Triangle Park, NC 27709; telephone number: (919) 541-1069; email address: [email protected]. Regional Office Contacts The following serve as points of contact for inquiries related to specific areas within the respective EPA Regional offices. The information can also be reviewed online at https://www.epa.gov/particle-pollution-designations and in the public docket for these 2024 annual PM2.5 NAAQS designations at https://www.regulations.gov under Docket ID No. EPA-HQ-OAR-2024-0078. ____________________________________ EPA regional office contacts Affected states ____________________________________ EPA Region 1, Lynne Hamjian, CT, ME, MA, NH, RI, VT. [email protected]. EPA Region 2, Richard Ruvo, NJ, NY, Puerto Rico, U.S. [email protected]. Virgin Islands. EPA Region 3, Michael Dunn, DE, DC, MD, PA, VA, WV. [email protected]. EPA Region 4, Denisse Diaz, AL, FL, GA, KY, MS, NC, SC, TN. [email protected]. EPA Region 5, John Mooney, IL, IN, MI, MN, OH, WI. [email protected]. EPA Region 6, James McDonald, AR, LA, NM, OK, TX. [email protected]. EPA Region 7, Dana Skelley, IA, KS, MO, NE. [email protected]. EPA Region 8, Adrienne Sandoval, CO, MT, ND, SD, UT, WY. [email protected]. EPA Region 9, Anita Lee, AZ, CA, HI, NV, American Samoa, [email protected]. Commonwealth of the Northern Mariana Islands, Guam. EPA Region 10, Angeles Herrera, AK, ID, OR, WA. [email protected]. ------------------------------------------------------------------------

Supplementary Information

Docket. The EPA has established a docket for this action under Docket ID No. EPA-HQ-OAR-2024-0078. All documents in the docket are listed in https://www.regulations.gov. Although listed, some information is not publicly available, e.g., Confidential Business Information (CBI) or other information the disclosure of which is restricted by statute. Certain other material, such as copyrighted material, is not placed on the internet and will be publicly available as PDF versions that can only be accessed on the EPA computers in the docket office reading room. Certain databases and physical items cannot be downloaded from the docket but may be requested by contacting the docket office at (202) 566-1744. With the exception of such material, publicly available docket materials and a plain language summary of the action are available electronically at https://www.regulations.gov. Written Comments. Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2024-0078, at https://www.regulations.gov (the EPA's preferred method) or the other methods identified in the ADDRESSES section. Once submitted, comments cannot be edited or removed from the docket. The EPA will publish any comment received to the Agency's public docket. Do not submit to the EPA's docket at https://www.regulations.gov any information you consider to be CBI, Proprietary Business Information (PBI), or other information the disclosure of which is restricted by statute. This type of information should be submitted as discussed below. 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). Please visit https://www.epa.gov/dockets/commenting-epa-dockets for additional submission methods; the full EPA public comment policy; information about CBI, PBI, or multimedia submissions; and general guidance on making effective comments. Submitting CBI. Do not submit information containing CBI to the EPA through https://www.regulations.gov. Clearly mark the part or all of the information that you claim to be CBI. For CBI information on any digital storage media that you mail to the EPA, note the docket ID, mark the outside of the digital storage media as CBI, and identify electronically within the digital storage media the specific information that is claimed as CBI. In addition to one complete version of the comments that includes information claimed as CBI, you must submit a copy of the comments that does not contain the information claimed as CBI directly to the public docket through the procedures outlined in Written Comments section above. If you submit any digital storage media that does not [[Page 63518]] contain CBI, mark the outside of the digital storage media clearly that it does not contain CBI and note the docket ID. Information not marked as CBI will be included in the public docket and the EPA's electronic public docket without prior notice. Information marked as CBI will not be disclosed except in accordance with procedures set forth in 40 Code of Federal Regulations (CFR) part 2. Our preferred method to receive CBI is electronic transmission using email attachments, File Transfer Protocol (FTP), or other online file sharing services (e.g., Dropbox, OneDrive, Google Drive). Electronic submissions must be transmitted directly to the Office of State Air Partnerships (OSAP) CBI Office at the email address [email protected] and, as described above, should include clear CBI markings and note the docket ID. If assistance is needed with submitting large electronic files that exceed the file size limit for email attachments, and if you do not have your own file sharing service, please email [email protected] to request a file transfer link. If sending CBI information through the postal service, please send it to the following address: U.S. Environmental Protection Agency, Attn: OSAP Document Control Officer, Mail Drop: C404-02, 109 T.W. Alexander Drive, P.O. Box 12055, Research Triangle Park, North Carolina 27711, Attention Docket ID No. EPA-HQ-OAR-2024-0078. The mailed CBI material should be double wrapped and clearly marked. Any CBI markings should not show through the outer envelope. Preamble acronyms and abbreviations. Throughout this preamble, the use of ``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We use multiple acronyms and terms in this preamble. While this list may not be exhaustive, to ease the reading of this preamble and for reference purposes, the EPA defines the following terms and acronyms here: CAA Clean Air Act CBI Confidential Business Information CFR Code of Federal Regulations DV Design Value EPA Environmental Protection Agency FR Federal Register FTP File Transfer Protocol NAAQS National Ambient Air Quality Standard or Standards OSAP Office of State Air Partnerships PBI Proprietary Business Information PM Particulate Matter SIP State Implementation Plan TAS Treatment in a Similar Manner as a State U.S.C. United States Code Table of Contents I. Overview of Action II. Legal Authority III. The EPA's Intended Approach to Area Designations

I. Overview

Under CAA section 107(d), the EPA is to issue area designations upon promulgation of a new or revised NAAQS. On February 7, 2024, the EPA promulgated revisions to the primary annual PM2.5 NAAQS to a level of 9.0 micrograms per cubic meter ([micro]g/m\3\) as described in 40 CFR 50.20.\1\ On July 17, 2026, the Northern District Court of California ordered the EPA to publish final designations for all areas of the country no later than February 6, 2027.\2\ Although EPA is appealing the order, EPA is also moving forward in the absence of action from the judiciary, to complete the designations. --------------------------------------------------------------------------- \1\ 89 FR 16202 (Mar. 6, 2024). \2\ All. of Nurses for Healthy Env'ts v. Zeldin, No. 26-cv- 03118-HSG (N.D. Cal. July 17, 2026). --------------------------------------------------------------------------- As a general matter, the first step in the designations process is for the Governors of States and territories, and Tribes, if they so choose, to submit initial area designations to the EPA. Whenever the EPA intends to modify a Governor's initial designation, the Agency must notify the State, territory, or Tribe no later than 120 days prior to promulgating final designations.\3\ These notifications are informally referred to as 120-day letters. --------------------------------------------------------------------------- \3\ The EPA notified Tribes that have obtained treatment in a similar manner as a state (TAS) under CAA section 301(d) and 40 CFR part 49 for purposes of CAA section 107(d), and those Tribes that may be affected by a nonattainment designation in the relevant State. --------------------------------------------------------------------------- This notice of availability provides notice of the EPA's intended approach for designations for the 2024 annual PM2.5 NAAQS under CAA section 107(d)(1)(B). The EPA invites public input regarding area designations during the 30-day comment period announced in this notice. To receive full consideration, input from the public must be submitted to the docket by the date provided in the DATES section of this document. This notice and opportunity for public comment does not affect any rights or obligations of any State, territory, or Tribe, or of the EPA, which might otherwise exist pursuant to CAA section 107(d).

II. Legal Authority

Following promulgation of a new or revised NAAQS, CAA section 107(d) requires the EPA to designate areas of the country as attainment, nonattainment, or unclassifiable for that NAAQS. CAA section 107(d)(1)(A)(i)-(iii) defines: (i) nonattainment, as any area that does not meet (or that contributes to ambient air quality in a nearby area that does not meet) the NAAQS; (ii) attainment, as any area (other than an area identified in clause (i)) that meets the NAAQS; and (iii) unclassifiable, as any area that cannot be classified on the basis of available information as meeting or not meeting the NAAQS. Generally, the designations process involves identifying areas of the country that either meet or do not meet the NAAQS, along with any nearby areas that are causing or contributing to NAAQS violations. The EPA calculates design values (DVs) at monitors to determine whether a given area has met the 2024 annual PM2.5 NAAQS, based on procedures outlined in 40 CFR part 50, Appendix N.\4\ The 2024 annual PM2.5 NAAQS is met at an ambient air quality monitoring site when the annual arithmetic mean, averaged over three years (i.e., the DV) is less than or equal to 9.0 [micro]g/m\3\. --------------------------------------------------------------------------- \4\ In accordance with 40 CFR part 50 Appendix N, PM2.5 measurements from the primary monitor and suitable collocated PM2.5 Federal Reference Method (FRM) or Federal Equivalent Method (FEM) may be used in a ``combined site data record'' to establish a PM2.5 design value to determine whether the NAAQS is met or not met at a particular PM2.5 monitoring site. For final area designations, the EPA intends to rely on Air Quality System (AQS) data from 2023-2025. --------------------------------------------------------------------------- In accordance with the statutory timeline prescribed under CAA section 107(d)(1)(A), Governors of each State or territory were required to submit a list of initial designations for all areas of their State or territory by February 7, 2025. Though not required, Tribal governments were encouraged to submit initial designations for their respective areas of Indian Country.\5\ These submissions generally relied on the 2021-2023 DVs and other information relevant to that time period. When promulgating final designations, the EPA will use the most recently available ambient air monitoring data and other information. The EPA intends to rely on DVs from the 2023-2025 period for promulgating final area designations. --------------------------------------------------------------------------- \5\ After promulgation of a new or revised NAAQS, each Governor or Tribal leader has an opportunity to submit initial area designations to the EPA. Consistent with the approach outlined in the EPA's 2011 Policy for Establishing Separate Air Quality Designations for Areas of Indian Country, in circumstances in which the Agency either does not receive an initial area designation letter from a Tribe, or receives a letter that does not specify designation of a separate area, the Agency intends to designate the relevant Tribe's Indian country as part of the surrounding multi- jurisdictional area. See memorandum from Stephen D. Page to Regional Air Directors, Regions 1-10, https://www.epa.gov/sites/default/files/2015-09/documents/20120117indiancountry.pdf. --------------------------------------------------------------------------- The EPA evaluates the initial area designation submissions from States, [[Page 63519]] the District of Columbia, territories, and Tribes as part of the Agency's duty to promulgate final designations for a new or revised NAAQS. CAA section 107(d)(1)(B)(ii) provides that, whenever the EPA intends to modify an initial designation for a State, territory, or Tribe, the Agency must notify the State, territory, or Tribe no later than 120 days before the date the Administrator promulgates final designations. CAA section 107(d)(1)(B)(ii) further requires the EPA to provide such State with an opportunity to demonstrate why any potential modification is inappropriate. Although not required by the CAA, the EPA has issued letters notifying all States, the District of Columbia territories, and certain Tribes of EPA's intended approach for finalizing designations, including instances where the State, territory, or Tribe declined to submit an initial area designation. The EPA's 120-day letters requested that the States provide additional information to the Agency within 30 days of receipt of the letters.