The Environmental Protection Agency (EPA) is proposing to approve a revision to the North Dakota State Implementation Plan (SIP) submitted by the State of North Dakota on November 11, 2016 and supplemented on March 15, 2021, that addresses amendments to the regional haze provisions of the North Dakota Administrative Code (NDAC). These revisions were submitted to remove certain regional haze requirements related to Best Available Retrofit Technology (BART) in the first planning period.

The Environmental Protection Agency (EPA) is taking final action to partially approve and partially disapprove the state implementation plan (SIP) revisions submitted by the State of California pursuant to the requirements of the Clean Air Act (CAA or ``Act'') for the implementation, maintenance, and enforcement of the 2015 national ambient air quality standards (NAAQS or ``standards'') for ozone. Specifically, the EPA is approving the SIP revision for all elements except those that relate to prevention of significant deterioration (PSD).

The Environmental Protection Agency (EPA) is proposing to approve a revision to Indiana's State Implementation Plan (SIP) to address changes to its air emissions monitoring rules for Portland cement plants. Indiana revised its rules for Portland cement plants to update the monitoring of particulate matter (PM) emissions to allow the use an additional monitoring method. This additional monitoring option is consistent with EPA's recent revisions to Federal requirements for Portland cement plants.

The Environmental Protection Agency (EPA) is proposing to approve a state implementation plan (SIP) revision submitted by the Delaware Department of Natural Resources and Environmental Control (DNREC). This SIP revision will fulfill Delaware's nonattainment new source review (NNSR) SIP element requirement for the 2015 8-hour ozone National Ambient Air Quality Standard (NAAQS). This action is being taken under the Clean Air Act (CAA).