EPA issued weakened National Emission Standards for Hazardous Air Pollutants (NESHAP) from coal- and oil-fired electric utility steam generating units (EGUs)—a rule commonly known as the Mercury and Air Toxics Standards for power plants, or simply MATS. The agency reverted to 2012 standards for non-mercury hazardous air pollutant metals from existing coal-fired plants, for filterable particulate matter (fPM) emission compliance demonstration requirements, and for mercury emissions from lignite-fired plants.