PM2.5/U.S. EPA September 30th Letter Describing Intended Approach for Arkansas Area Designations: Arkansas Department of Energy and Environment Response

Arkansas Department of Energy and Environment (“E&E”) Secretary Shane Khoury sent an October 30th letter to United States Environmental Protection Agency (“EPA”) Region 6 addressing the federal agency’s September 30, 2026 “120-day Letter” on Intended Area Designations for the 2024 Primary Annual PM2.5 NAAQS. See Docket ID No. EPA-HQ-OAR-2024-0078.

The E&E letter provides Arkansas’ views on designation of Air Quality Control Regions (“AQCRs”) in the state as either attainment/unclassifiable or nonattainment for the 2024 primary annual fine particulate matter (“PM2.5”) National Ambient Air Quality Standard (“NAAQS”).

Sections 108 and 109 of the Clean Air Act require that EPA identify air pollutants utilizing certain criteria and set NAAQS for each. Particulates are one of the six air pollutants currently designated as criteria air pollutants and are therefore subject to NAAQS. Section 109 requires that EPA promulgate primary NAAQS for the pollutants identified under Section 108.

Section 109(d)(1) of the Clean Air Act mandates a periodic review of each NAAQS. Depending on the results of the review, EPA must determine whether the existing air quality criteria and NAAQS should be revised.

EPA had modified under the Biden Administration the PM2.5 to a more restrictive 9.0 µg/m3. The previous PM2.5 standard was 12.0 µg/m3. However, under the Trump Administration EPA has argued that that the revised PM2.5 NAAQS was an unlawful tightening. The federal agency unsuccessfully requested that a federal appellate court vacate the rule before an area designation deadline of February 7, 2026.

EPA subsequently notified all 50 states, the District of Columbia, 5 territories, and 67 Tribes of its intended approach for area designations under the Biden-era 2024 revised NAAQS for PM2.5. Further, EPA provided an opportunity for states, territories, and Tribes to submit additional information within 30 days along with a Notice of Availability in the Federal Register to receive feedback.

EPA stated that the opportunities for further input represented a step toward complying with the court order issued by the U.S. District Court for the Northern District of California requiring designations for AQCRs by February 6, 2027.

In response to the September 30th EPA Region 6 letter, E&E states that it agrees with the federal agency’s intention to designate most areas in the State attainment/unclassifiable. Further, E&E states that for each Arkansas area that Enclosure 1 identifies as possibly not meeting the standard, it explains why EPA should designate that area as unclassifiable. Those areas include:

• Pulaski County, in the Little Rock-North Little Rock-Conway, AR Core Based Statistical Area (“CBSA”).
• Garland County, in the Hot Springs, AR CBSA.
• Union County, in the El Dorado, AR CBSA.
• Little River and Miller Counties, the Arkansas portion of the Texarkana, TX-AR CBSA.

By way of summary, Arkansas states and further amplifies on the following arguments:

• The information available to EPA supports an unclassifiable designation.
• The court-ordered schedule has left the necessary analyses incomplete.
  • Fire-influenced data have not been reviewed.
  • Contribution to the Texarkana, Texas monitor has not been analyzed.
• The Arkansas Department of Energy and Environment – Division of Environmental Quality will submit exceptional events demonstrations.

A copy of the E&E letter can be found here.