Air Plan Approval; Missouri; Regional Haze Plan and Prong 4 (Visibility) for the 2012 PM2.5, 2010 NO2, 2010 SO2, and 2008 Ozone NAAQS

The Environmental Protection Agency (EPA) is taking several final actions regarding the Missouri State Implementation Plan (SIP). Three SIP actions relate to how the state addresses transport as related to visibility impairment in Class 1 areas and the 2012 Fine Particulate Matter (PM<INF>2.5</INF>), 2010 Nitrogen Dioxide (NO<INF>2</INF>), 2010 Sulfur Dioxide (SO<INF>2</INF>), and 2008 Ozone National Ambient Air Quality Standards (NAAQS): The EPA is approving the portion of the state's September 5, 2014 Five-year Progress Report for the State of Missouri Regional Haze Plan and a subsequently submitted letter dated July 31, 2017, which clarified that the state was changing from reliance on the Clean Air Interstate Rule (CAIR) to reliance on the Cross State Air Pollution Rule (CSAPR) for certain regional haze requirements; the EPA is converting its limited approval/ limited disapproval of the state's Regional Haze Plan to a full approval; and the EPA is approving the states' submissions addressing the Clean Air Act (CAA or the Act) provisions that prohibit emissions activity in one state from interfering with measures to protect visibility in another state (prong 4) of the state's infrastructure SIP submittals for the 2008 Ozone, the 2010 Nitrogen Dioxide (NO<INF>2</INF>), the 2010 Sulfur Dioxide (SO<INF>2</INF>), and the 2012 Fine Particulate Matter (PM<INF>2.5</INF>) NAAQS. Finally, based on EPA's approval of the portion of the state's September 5, 2014, Five-year Progress Report that clarified that the state was changing from reliance on CAIR to reliance on CSAPR for certain regional haze requirements and conversion of its limited approval/limited disapproval of the state's Regional Haze Plan to a full approval, the EPA is withdrawing the June 7, 2012, Federal Implementation Plan (FIP) for regional haze.