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Mon Valley Stench Returns, GASP Again Calls on ACHD for Public Update

CreateLab’s SmellPGH app received a smattering of odor reports Saturday from local residents, one of whom said the outside air smelled like “someone mixed rotten eggs with manure and set it on fire.” 

If you were among those who asked yourself and others, “What. Is. That. STENCH?” or made complaints about an industrial, sulfur-like odor this past weekend, you might be interested to know that Saturday marked the 36th day in 2021 that hydrogen sulfide (H2S) levels exceeded the state air quality standard at the Allegheny County Health Department’s air quality monitor in Liberty Borough.

The 24-hour average was 0.008 ppm, exceeding Pennsylvania’s limit of 0.005 ppm. For those keeping track: There have also been 12 such H2S exceedances at ACHD’s air quality monitor in North Braddock.

If you haven’t had the pleasure of smelling it: Hydrogen sulfide is a colorless gas that’s recognizable by its rotten-egg odor. It’s a stench our friends in the Mon Valley (and those downwind of it) endure all too often.

While U.S. Steel has suggested area sewage treatment plants are the culprit for the Mon Valley’s H2S issues, it’s worth noting that its Clairton Coke Works was the largest emitter of hydrogen sulfide in the state on an annual basis every year 2010-2019. Of course, past results are not a guarantee of future performance, but we are not aware of any reason to doubt this trend has continued up through the present.

“These exceedances happen too often and impact residents’ quality of life too much,” GASP Executive Director Patrick Campbell said. “The Allegheny County Health Department cannot continue to stay silent. We are calling on ACHD to better communicate these exceedances – what is causing them and what is being done to fix them – to the public.”

Here’s a snapshot of Allegheny County’s H2S exceedances so far this year:

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