Mentioned 10× · first seen 05-jul-2026 · last seen 17-aug-2026

PM2.5 NAAQS Nonattainment Areas

Current understanding

Tracks EPA actions on nonattainment area classifications, attainment deadlines, and reclassifications under the fine particulate matter (PM2.5) National Ambient Air Quality Standards. Includes ‘Serious’ area attainment date extensions, which the Clean Air Act allows when a state meets statutory criteria (e.g., attainment as expeditiously as practicable, most stringent measures adopted). Practical effect touches SIP obligations, control measure timelines, and public-health exposure in affected regions.

Evidence log

2026-08-13 — Determination of Attainment by the Attainment Date and Clean Data Determination for the 2012 Annual Fine Particulate Standard; Plumas County, California: 2026 final rule — EPA finalizes that the Portola, Plumas County, CA Serious PM2.5 nonattainment area attained the 2012 annual PM2.5 NAAQS by the Dec 31, 2025 deadline and issues a clean data determination, suspending certain attainment-related planning requirements while the nonattainment designation remains in place. (novelty: 2)
2026-08-06 — Partial Approval and Partial Disapproval of Air Quality State Implementation Plans; Arizona; Prevention of Significant Deterioration Infrastructure Requirements for the 2012 Fine Particulate Matter National Ambient Air Quality Standard: 2026 proposed rule — EPA proposes partial approval/partial disapproval of Arizona’s 2012 PM2.5 NAAQS PSD infrastructure SIP: approving ADEQ, Maricopa County, and Pinal County submittals while disapproving the Pima County portion, affecting Clean Air Act §110(a)(2) infrastructure obligations for preventing significant deterioration in PM2.5 attainment areas. (novelty: 2)
2026-04-27 — FIRE Act: 2025 — FIRE Act (HR6387) would broaden Clean Air Act exceptional-events treatment for prescribed fire and wildfire-mitigation-related meteorological conditions, potentially enabling exclusion of additional smoke-influenced days from PM2.5 design values used in nonattainment and attainment-date determinations. (novelty: 3)
2026-04-17 — FENCES Act: 2025 — FENCES Act (introduced) would provide relief from PM2.5 nonattainment designations, sanctions, and fees when air-quality shortfalls stem from out-of-state, foreign, or exceptional-event emissions (e.g., wildfire smoke), directly relevant to western Serious-area attainment struggles. (novelty: 3)
2026-05-14 — Determination of Attainment by the Attainment Date and Clean Data Determination for the 2012 Annual Fine Particulate Standard; Plumas County, California: 2026 proposed rule — EPA proposes that the Portola, Plumas County, CA Serious nonattainment area attained the 2012 annual PM2.5 NAAQS by its Dec 31, 2025 deadline and issues a clean data determination that would suspend certain Clean Air Act planning requirements while the area’s nonattainment designation remains in place. (novelty: 2)
2026-06-11 — Finding of Failure To Attain the 2006 24-Hour PM2.5 Standards; California; San Joaquin Valley; Error Correction: 2026 final rule — EPA corrects its 2020 action by denying California’s attainment date extension for the 2006 24-hour PM2.5 NAAQS in the San Joaquin Valley and finalizing a failure-to-attain determination, triggering a revised SIP obligation for the state (following court remand). (novelty: 2)
2026-06-11 — Attainment Date Extension for the San Joaquin Valley, California 2012 Annual PM2.5 Fine Particulate Matter Nonattainment Area: 2026 — EPA proposed rule to extend San Joaquin Valley’s 2012 annual PM2.5 ‘Serious’ area attainment deadline from Dec 31, 2025 to Dec 31, 2030, finding California met statutory extension criteria; parallels the concurrent South Coast extension action. (novelty: 2)
2026-06-11 — Attainment Date Extension for the South Coast, California 2012 Annual PM2.5 Fine Particulate Matter Nonattainment Area: cross-connection with ozone-reclassification-sip-requirements: Both concern Clean Air Act nonattainment area classifications and the SIP/deadline consequences when statutory attainment dates cannot be met. (novelty: 2)