Air Approval and Promulgation of Implementation Plans; Montana; Libby 1997 Annual PM2.5 Limited Maintenance Plan and Redesignation Request
In this document, the Environmental Protection Agency (EPA or Agency) is taking three separate but related actions. First, EPA is finalizing its determination that the Libby fine particulate matter (PM<INF>2.5</INF>) nonattainment area (Libby Area) is attaining the 1997 Annual PM<INF>2.5</INF> national ambient air quality standards (NAAQS or standard) based on 2014-2021 data. Secondly, EPA is finalizing approval of Montana's plan for maintaining the 1997 Annual PM<INF>2.5</INF> NAAQS (limited maintenance plan). Lastly, the EPA is finalizing approval of the redesignation of the Libby Area to attainment for the 1997 Annual PM<INF>2.5</INF> NAAQS, submitted by the State of Montana on June 24, 2020. The EPA is taking this action pursuant to the Clean Air Act (CAA).