Two workers were injured at U.S. Steel’s Clairton Coke Works early Wednesday after a buildup of gases ignited at the plant.
The Allegheny County Health Department said in a statement the incident occurred at the “B” Battery at the plant.
The department said the accident occurred as a result of a “hydraulic failure in a switch of the battery, which led to a buildup of combustible material” in one part of the battery, “which then ignited.”
The agency said an audible “boom” was heard around the plant and that some emissions leaked out of the facility.
Outdoor pollution levels rose around the plant after the explosion, but they never exceeded federal short-term clean air standards, the department said.
The two injured workers needed first aid after getting material in their eyes and were sent to a nearby hospital and released. They were later allowed to go back to work, according to a statement from U.S. Steel spokeswoman Amanda Malkowski.
Malkowski said U.S. Steel has taken the battery offline while it investigates.
Clairton is the largest coke plant in the U.S. The plant has several batteries, where it turns coal into coke, a key component of steelmaking.
U.S. Steel is Allegheny County’s single largest source of several pollutants like soot, benzene and sulfur pollution.
