Earthworks’ investigation with optical gas imaging (OGI) cameras on March 11, 2019 detected significant plumes of hydrocarbons and volatile organic compounds (VOCs) coming from the flares. The OGI camera is an industry-standard tool for visualizing air pollution from oil and gas development, and Earthworks’ camera operators are trained and certified to differentiate these gases from heat.United States Steel Corporation Mon Valley Works Irvin Plant West Mifflin, Allegheny County, PA (40.332578, -79.901805) Filmed 3/11/2019 All video taken by a certified thermographer with an industry standard optical gas imaging camera, the FLIR GasFinder 320. This $100,000 camera is specially calibrated to detect methane and other VOCs, and is used by the oil & gas industry and regulators for that purpose.