Approval and Promulgation of Implementation Plans; Mississippi; Prevention of Significant Deterioration Rules: Nitrogen Oxides as a Precursor to Ozone

EPA is taking final action to approve a portion of a revision to the Mississippi State Implementation Plan (SIP), submitted by the Mississippi Department of Environmental Quality (MDEQ), to EPA on November 28, 2007. The revision amends Mississippi's prevention of significant deterioration (PSD) permitting regulations in the SIP to address permit requirements promulgated in the 1997 8-Hour Ozone National Ambient Air Quality Standards (NAAQS) Implementation Rule- Phase II (hereafter referred to as the "Ozone Implementation New Source Review (NSR) Update"). The Ozone Implementation NSR Update revised permit requirements relating to the implementation of the 1997 8-hour ozone NAAQS specifically incorporating nitrogen oxides (NO<INF>X</INF>) as a precursor to ozone. EPA's approval of Mississippi's provisions to include NO<INF>X</INF> as an ozone precursor into the Mississippi SIP is based on EPA's determination that Mississippi's SIP revision related to these provisions complies with Federal requirements.