The Allegheny County Council voted unanimously on Tuesday to drastically decrease the allowable amount of emissions from the Clairton Coke Works plant, one of the final reforms agreed to following the 2018 plant explosion that triggered an air quality lawsuit.
The revisions, recommended by the Allegheny County Health Department (ACHD), will require that the maximum quantity of hydrogen sulfide per unit of coke oven gas be reduced to 25 grains, from the previous maximum of 70 grains.
“This is a significant decrease,” said Annie Fox, senior attorney for Clean Air Council, a nonprofit air quality organization.
A consent degree was entered into after a 2018 explosion led to a period of 102 days in which emissions were 25 times the allowed amount. As part of the decree, U.S. Steel agreed to permanently shut down one of its oven batteries and undergo $37 million in upgrades.
Fox said that during the 102-day period in which emissions exceeded recommended levels, local doctors began to report children with aggravated asthma and breathing problems that did not correlate with the January season. The Clean Air Council, joined by the ACHD, sued U.S. Steel, citing violations of the Clean Air Act, and the company entered into the consent decree in March 2024.
“As part of the consent decree, U.S. Steel had to do $37 million worth of improvements, including $17.5 million to replace deteriorating equipment that was desperately in need of upgrades, and was required to have preventative maintenance programs that should have been in place,” Fox said.
U.S. Steel also agreed to pay $5 million to the two local bodies charged with funding community projects to improve air quality.
“Battery #15 is now permanently idled, and the coke oven gas cleaning facility has been upgraded,” said Andrew Fulton, spokesperson for U.S. Steel. “The rule changes reflect our commitment to follow through on the requirements of the consent decree. We will continue to make environmental excellence a priority at the Clairton Plant and all of our Mon Valley Works facilities.”
Since the consent decree was entered, the Clairton Coke Works site has repeatedly been cited for exceeding emissions limits. In August 2025, an explosion at the site killed two workers and injured nearly a dozen others.
Fox said communities in the Mon Valley around the Clairton plant have been fighting tirelessly for decades to get the local government to recognize the damage to homes from pollution and rising health concerns.
“Over the past couple of years, monitors have been showing very high levels of hydrogen sulfide and community members have had to endure this; the stench is very unpleasant,” Fox said.