Air Plan Approval; Indiana; Air Quality Standards Update for the 2015 Ozone Standard

The Environmental Protection Agency (EPA) is approving a September 7, 2017, request by the Indiana Department of Environmental Management (IDEM) to revise the Indiana state implementation plan (SIP) for ozone. IDEM revised its ozone standard in order to be consistent with EPA's 2015 revisions to the 8-hour national ambient air quality standards (NAAQS). IDEM also revised references to the monitoring test methods in its rules to be consistent with the current EPA test methods. EPA is also approving administrative revisions to regulations addressing other ambient air quality standards.