EPA is proposing to revise provisions applicable to greenhouse gases (GHG) in the EPA's Prevention of Significant Deterioration (PSD) and title V permitting regulations. This action is in response to the 23 Jun 2014, U.S. Supreme Court's decision in Utility Air Regulatory Group v. EPA and the 10 Apr 2015, Amended Judgment by the United States Court of Appeals for the District of Columbia Circuit (D.C. Circuit) in Coalition for Responsible Regulation v. EPA. The proposed revisions involve changes to several regulatory definitions in the PSD and title V regulations, revisions to the PSD provisions on GHG Plantwide Applicability Limitations (PALs), and revisions to other provisions necessary to ensure that neither the PSD nor title V rules require a source to obtain a permit solely because the source emits or has the potential to emit GHGs above the applicable thresholds. EPA is also proposing a significant emissions rate for GHGs under the PSD program that would establish an appropriate threshold level below which BACT is not required for a source's GHG emissions. Comments must be received on or before 2 Dec 2016. POC is Ms. Carrie Wheeler, U.S. EPA, Office of Air Quality Planning & Standards, Air Quality Policy Division, (C504-01), Research Triangle Park, NC 27711, Tel: (919) 541-9771, email: wheeler.carrie@epa.gov (Federal Register; 3 October 2016 [Proposed Rules], pages 68110-68147).