Promulgation of State Implementation Plan Revisions; Infrastructure Requirements for the 1997 and 2006 PM2.5 National Ambient Air Quality Standards; Montana

EPA is partially approving and partially disapproving the State Implementation Plan (SIP) submission from the State of Montana to demonstrate that the SIP meets the infrastructure requirements of the Clean Air Act (CAA) for the National Ambient Air Quality Standards (NAAQS) promulgated for fine particulate matter (PM<INF>2.5</INF>) on July 18, 1997 and on October 17, 2006. The CAA requires that each state, after a new or revised NAAQS is promulgated, review their SIPs to ensure that they meet infrastructure requirements. The State of Montana submitted a certification of their infrastructure SIP for the 1997 and 2006 PM<INF>2.5</INF> NAAQS on February 10, 2010. EPA is acting separately on the portions of the February 10, 2010 submission relating to interstate transport of air pollution.