Approval and Promulgation of Air Quality Implementation Plans; Michigan; Withdrawal of the Federal Implementation Plan for the Detroit Sulfur Dioxide Area

Official abstract: The U.S. Environmental Protection Agency (EPA) is proposing to withdraw the Federal Implementation Plan (FIP), promulgated on October 12, 2022 (the "2022 FIP"), for attaining the 2010 1-hour primary sulfur dioxide (SO<INF>2</INF>) National Ambient Air Quality Standard (NAAQS) in the Detroit area. On May 19, 2025, the EPA approved a revision to Michigan's State Implementation Plan (SIP) for attaining the 2010 1-hour primary SO<INF>2</INF> NAAQS in the Detroit area, rendering the 2022 FIP duplicative. The EPA is proposing this action pursuant to Clean Air Act (CAA) section 110.