Hours-long Clairton Coke Works breakdown sends high levels of pollutants into air

CLAIRTON, Pa. — U.S. Steel is responding to a reported breakdown at its Clairton Coke Works plant that sent high levels of pollution into the air.

According to the Allegheny County Health Department, the incident occurred Monday night around 7 p.m. while repairs were being made to a control room. All equipment was back online by 3 a.m.

Health officials say preliminary information shows that during the breakdown, a control room that removes harmful chemicals from gas produced during coke-making was shut down and bypassed. The coke oven gas created during the breakdown was only partially cleaned by the remaining control systems, allowing for high levels of hydrogen sulfide and sulfur dioxide to be released.

In a statement, U.S. Steel said its crews worked quickly to “isolate the cause of the problem and make repairs,” then bring the control room back online.

“The plant has been in normal operation since the early morning hours of June 3. U. S. Steel followed all response protocols to ensure the safety of its employees and the community. The Allegheny County Health Department was notified, in accordance with our operating permit,” the statement reads in part.

Health officials say U.S. Steel has a week to submit a full report explaining what happened.

Download the FREE WPXI News app for breaking news alerts.

Follow Channel 11 News on Facebook and Twitter. | Watch WPXI NOW

©2025 Cox Media Group