The U.S. Environmental Protection Agency (EPA) has proposed a rule to revise mercury and air toxins emissions limits for newly built coal- and oil-fired power plants. In December 2011, EPA issued its first mercury and air toxins standards (MATS) for new and existing power plants. The standards for new plants were more stringent than those for existing plants.

After receiving a petition to reconsider the standards for new plants from the Institute for Clean Air Companies and after the rule was challenged in the D.C. Circuit Court of Appeals, EPA agreed to reconsider the standards for new plants. Industry had complained that the standards for new plants were too stringent and that the required mercury concentrations were so low that they could not be continuously monitored. EPA will accept comments for 30 days following publication in the Federal Register.