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This webpage is dedicated to state implementation plan (SIP) documents that pertain to every county in the state of Indiana. Other Indiana SIP documents can be accessed and viewed through the Office of Air Quality’s (OAQ’s) Criteria Pollutants webpage. In short, SIPs function for the implementation, maintenance and enforcement of National Ambient Air Quality Standards (NAAQS) as required by Section 110 of the federal Clean Air Act (CAA).
Transportation Conformity documents are available on the Transportation Conformity page.