Litigation—Environment: EPA Reinforces Standards to Use “Representative Data” After Sierra Club

On January 22, 2013, in Sierra Club v. EPA, the US Court of Appeals for the District of Columbia issued an opinion that addressed some Prevention of Significant Deterioration (PSD) permitting program issues. Following this case, on March 4, 2013, the EPA issued guidance entitled “Draft Guidance for PM2.5 Permit Modeling,” and on May 20, 2014, issued its final “Guidance for PM2.5 Permit Modeling.” Sierra Club held that the Environmental Protection Agency lacked the legal authority to create an exemption to the PSD preconstruction data-gathering requirement through the use of Significant Monitoring Concentrations (SMCs).