Approval and Promulgation of Air Quality Implementation Plans; Indiana; Revisions to Particulate Matter Rules

On March 14, 2008, EPA proposed to approve Indiana's February 21, 2008, request to revise its particulate matter State Implementation Plan (SIP) for sources in Clark, Dearborn, Dubois, Howard, Lake, Marion, St. Joseph, Vanderburgh, Vigo, and Wayne Counties. This SIP revision updated facility names, revised formatting, removed sources no longer in operation, and revised some emission limits. The State submitted air quality modeling analyses that demonstrated that air quality will continue to be protected in the five counties where some emission limits increased. EPA received one letter containing several comments on the proposal. After review of these comments and for the reasons discussed below, EPA is approving this SIP revision request.