Approval and Promulgation of Air Quality Implementation Plans; Illinois; Indiana; Michigan; Minnesota; Ohio; Wisconsin; Infrastructure SIP Requirements for the 2006 PM2.5 National Ambient Air Quality Standards; Indiana NSR/PSD

EPA is taking final action to approve most elements, and disapprove narrow portions of other elements, of State Implementation Plan (SIP) submissions by Illinois, Indiana, Michigan, Minnesota, Ohio, and Wisconsin regarding the infrastructure requirements of the Clean Air Act (CAA) for the 2006 24-hour fine particle national ambient air quality standards (2006 PM<INF>2.5</INF> NAAQS). The infrastructure requirements are designed to ensure that the structural components of each State's air quality management program are adequate to meet the State's responsibilities under the CAA. EPA is also taking final action to approve portions of a submission from Indiana addressing EPA's requirements for its new source review (NSR) and prevention of significant deterioration (PSD) program. The proposed rulemaking was published on August 2, 2012. During the comment period, which ended on September 4, 2012, EPA received five comment letters. The concerns raised in these letters, as well as EPA's responses, will be addressed in this final action.