The Environmental Protection Agency (EPA) is approving revisions to the State Implementation Plan (SIP) for Indiana and revisions to the operating permit program for Ohio. The revisions incorporate changes to the definition of ``chemical process plants'' under Indiana's Prevention of Significant Deterioration (PSD) regulations and under Ohio's operating permit program. EPA also provided an opportunity for public comment on similar changes to the definition of ``major stationary source'' in Ohio's PSD regulations that were approved into the SIP on October 28, 2014. The changes to the State rules described below are approvable because they are consistent with EPA regulations governing state PSD and title V programs and will not interfere with any applicable requirement concerning attainment and reasonable further progress (as defined in section 171 of the Clean Air Act (CAA)), or any other applicable requirement of the CAA. EPA proposed to approve this action on January 19, 2022, and received no adverse comments.