The Environmental Protection Agency (EPA) is withdrawing the initial nonattainment designation for portions of the Outagamie County, Wisconsin, area for the 2010 sulfur dioxide (SO<INF>2</INF>) primary National Ambient Air Quality Standard (NAAQS) and is finalizing a designation of attainment/unclassifiable for the area. The EPA Administrator signed an action on December 21, 2020, to designate certain areas in the United States (U.S.) for the 2010 SO<INF>2</INF> NAAQS, including the Outagamie County area. This action supplements the EPA's December 2020 designations, published in the Federal Register of March 26, 2021, which have not yet taken effect.