Environmentalists are taking legal action against United States Steel Corporation (U.S. Steel) because of pollution in Pittsburg’s Mon Valley. The Clean Air Council and PennEnvironment are suing the steel manufacturer for violating the Clean Air Act after a fire broke out at a facility in Clairton, Pennsylvania. “We cannot expect families to sustain this kind of health burden and trauma, and we cannot expect kids to learn, grow and flourish when they are confined to their homes, unable to breathe,” the head of PennEnvironment, Ashleigh Deemer, explained in a statement. Related: California’s largest utility company plans massive sale of natural gas division Deemer added that the fire only highlighted ongoing issues at the U.S.