On August 11, 2025, an explosion at the U.S. Steel Clairton Coke Works plant in Clairton, Pennsylvania, about 15 miles south of Pittsburgh, resulted in one confirmed death, two people unaccounted for, and dozens injured, with some trapped under rubble. The incident, reported around 10:51 a.m., prompted a Level 3 mass casualty response, with emergency crews, including 15 additional ambulances, dispatched to the scene. At least nine individuals were hospitalized with unspecified injuries, many described as non-life-threatening. The explosion caused a loud boom, felt like thunder by nearby workers, and sent black smoke spiraling into the sky over the Monongahela Valley.
The Allegheny County Health Department is monitoring air quality, advising residents within one mile of the plant to stay indoors, close windows, and avoid drawing in outside air due to potential hazards, though soot and sulfur dioxide levels have not exceeded federal standards. The Bureau of Alcohol, Tobacco, Firearms and Explosives is assisting with the response, and a rescue operation is ongoing. The Clairton plant, the largest coking operation in North America, produces 4.3 million tons of coke annually and employs about 1,400 workers. It has a history of safety and pollution issues, including a 2018 fire that damaged pollution controls and led to lawsuits over air quality violations. Pennsylvania officials, including Governor Josh Shapiro and Senator John Fetterman, have expressed condolences and urged residents to follow local authorities’ guidance as the situation develops.