The Environmental Protection Agency (EPA) is approving a State Implementation Plan (SIP) revision submitted by the State of Alaska, through the Alaska Department of Environment Conservation, on January 9, 2017. The revision was submitted by Alaska in response to a finding of substantial inadequacy and SIP call published on June 12, 2015, for a provision in the Alaska SIP related to excess emissions during startup, shutdown, and malfunction (SSM) events. EPA is approving the SIP revision and finds that such SIP revision corrects the deficiency identified in the June 12, 2015, SIP call.

The Environmental Protection Agency (EPA) is approving revisions to the Alaska State Implementation Plan (SIP) submitted on November 10, 2020. The revisions update the adoption by reference of certain Federal air regulations and add a pre-approved emission limit option that may be used to permit diesel engine facilities, among other changes. The EPA's approval makes the revisions federally enforceable as part of the Alaska SIP.

The Environmental Protection Agency (EPA) is making an interim final determination that the Arizona Department of Environmental Quality (ADEQ) has submitted a revised rule on behalf of the Maricopa County Air Quality Department (MCAQD or County) that corrects deficiencies in its Clean Air Act (CAA or Act) state implementation plan (SIP) provisions concerning ozone nonattainment requirements for controlling oxides of nitrogen (NO<INF>X</INF>) at power plants.

The Environmental Protection Agency (EPA) is proposing to approve a state implementation plan (SIP) revision submitted by the State of Delaware. This revision pertains to the reduction of the maximum allowable sulfur content limit for distillate fuels, from a current limit of 3,000 parts per million (ppm) (0.3% by weight) to 15 ppm (0.0015% by weight) and residential fuels from a current limit of 1.0% by weight to 0.5% by weight. This revision also adds requirements for sampling and testing along with certification and recordkeeping.