Proposed rule · 2026-20468

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

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 (PM<INF>2.5</INF>) National Ambient Air Quality Standard (NAAQS) (the 2024 annual PM<INF>2.5</INF> 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 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.