Final rule · 2026-16510

Determination of Attainment by the Attainment Date and Clean Data Determination for the 2012 Annual Fine Particulate Standard; Plumas County, California

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 ("PM<INF>2.5</INF>") 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.