The U.S. Court of Appeals for the District of Columbia Circuit (DC Circuit) recently issued a decision to grant the U.S. Environmental Protection Agency’s (USEPA’s) request to allow the Cross-State Air Pollution Rule (CSAPR) to take effect January 1, 2015, superseding the federal Clean Air Interstate Rule (CAIR). Massachusetts is currently not subject to the CSAPR program, but the federal Clean Air Act and the Massachusetts State Implementation Plan (SIP) have anti-backsliding provisions that do not allow the MassDEP ease its ozone reduction requirements, and is required to maintain the nitrogen oxide (NOX) emission reductions required by the MassCAIR program under 310 CMR 7.32. Therefore, MassCAIR will remain in place until such time as the MassDEP replaces the program. Click here for a copy of the letter sent by the MassDEP to MassCAIR facilities and other stakeholders.