What's Going on at U.S. Steel? To Fix Mon Valley's H2S Problem

Air across the region was hot, humid, and at times unhealthy this past weekend, with Code Orange Air Quality Action Days issued by PA DEP for elevated levels of ozone on both Saturday and Sunday. But if you were anywhere near the Mon Valley and asked yourself, “What’s that SMELL?”, it was probably because of hydrogen sulfide (H2S).

The colorless gas is most commonly recognized by its “rotten egg” odor and concentrations exceeded the Pennsylvania 24-hour average standard of 0.005 ppm on both Saturday (0.007 ppm) and Sunday (0.009 ppm) at Allegheny County Health Department’s air quality monitor in Liberty borough.

“There have been 24 H2S exceedances so far this year at Liberty. That’s only one less than in all of 2020, but it’s also worth noting that the first exceedance in 2021 at that monitor didn’t occur until March 3,” GASP staff attorney Ned Mulcahy explained. “In other words, there has been an average of one H2S exceedance every fourth day for the past three months. That’s downright awful.”
The spate of exceedances so far this year begs the question: What is going on at U.S. Steel’s Clairton Coke Works?

Here's what we know and what we're calling on public officials to do.