The Environmental Protection Agency (EPA) is taking final action to disapprove the visibility transport (prong 4) portions of revisions to the Mississippi State Implementation Plan (SIP), submitted by the Mississippi Department of Environmental Quality (MDEQ), addressing the Clean Air Act (CAA or Act) infrastructure SIP requirements for the 2008 8-hour Ozone, 2010 1-hour Nitrogen Dioxide (NO<INF>2</INF>), 2010 1-hour Sulfur Dioxide (SO<INF>2</INF>), and 2012 annual Fine Particulate Matter (PM<INF>2.5</INF>) National Ambient Air Quality Standards (NAAQS). The CAA requires that each state adopt and submit a SIP for the implementation, maintenance, and enforcement of each NAAQS promulgated by EPA, commonly referred to as an "infrastructure SIP." Specifically, EPA is disapproving the prong 4 portions of Mississippi's May 29, 2012; July 26, 2012; February 28, 2013; June 20, 2013; and December 8, 2015, infrastructure SIP submissions. All other applicable infrastructure requirements for these SIP submissions have been or will be addressed in separate rulemakings.