Determination of Attainment by the Attainment Date and Clean Data Determination for the 2012 Annual Fine Particulate Standard; Plumas County, California
Key claim: EPA has finalized that the Portola area in Plumas County, California met the 2012 annual fine-particle air standard by the end of 2025 and qualifies for a clean data determination based on recent monitoring.
Abstract
(Rule · Environmental Protection Agency) The Environmental Protection Agency (EPA) is finalizing our determination that the Portola nonattainment area in Plumas County, California, attained the 2012 annual fine particulate matter (“PM2.5”) national ambient air quality standard (NAAQS or “standard”) by the December 31, 2025 “Serious” area attainment date. This determination is based on ambient air quality monitoring data from 2023 through 2025. We are also finalizing a clean data determination (CDD) based on the 2023 through 2025 data and our evaluation of preliminary air quality monitoring data from 2026.
Why this matters
Attainment and clean-data determinations reduce ongoing SIP planning burdens for state and local air agencies while signaling measurable improvement in local PM2.5 exposure — a public-health-relevant outcome in a small rural California community historically affected by wood-smoke and wildfire-influenced particulate levels. The action illustrates how EPA processes routine Clean Air Act attainment findings even as larger California PM2.5 areas (San Joaquin Valley, South Coast) continue to struggle with the same 2012 standard.