The Allegheny County Health Department is investigating elevated sulfur levels in coke oven gas reported over several hours from Monday evening into Tuesday morning at U.S. Steel’s Clairton Coke Works.
Health Department officials said a report they received from U.S. Steel indicated one of the facility’s control rooms, which normally removes harmful chemicals like hydrogen sulfide and ammonia from the oven gas, was shut down for repairs and bypassed between about 7 p.m. Monday and 3 a.m. Tuesday.
During that time, the gas was only partly cleaned by two other remaining control rooms.
During the control room breakdown, county health officials measured elevated levels of hydrogen sulfide and sulfur dioxide at their Liberty monitor. Hydrogen sulfide peaked there at 32 part per billion at 9 p.m. Monday, compared to the state regulatory level of 5 parts per billion and normal levels below one part per billion in the county.
Sulfur dioxide concentration hit a high mark of 47 parts per billion at 10 p.m. Monday. It had fallen to one part per billion at 1 p.m. Tuesday.
The Occupational Safety and Health Administration has set a ceiling limit of 20 parts per million for hydrogen sulfide in workplace air. According to the Agency for Toxic Substances and Disease Registry, exposure to low concentrations of the gas may cause irritation to the eyes, nose or throat and may cause difficulty in breathing for some asthmatics.
Short-term exposures to sulfur dioxide can harm the respiratory system and make breathing difficult, according to the Environmental Protection Agency.
U.S. Steel has seven days to submit a full report explaining what happened in the control room, county health officials said.
In a statement provided to TribLive news partner WTAE, the company said, “Crews worked quickly to isolate the cause of the problem and make repairs, which were completed within a couple of hours of the shutdown. U. S. Steel then began the process of bringing control room five back online, which took several more hours.
“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.”
