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Mon Valley Experiences More Malodors, Liberty Monitor Again Exceeds PA Air Quality Standard

Updated: Sep 12, 2022

So, did you smell it yesterday – that all-too-familiar stench of rotten eggs? Because Wednesday marked the 37th day in 2021 that hydrogen sulfide (H2S) levels exceeded the state air quality standard at Allegheny County Health Department’s air quality monitor in Liberty Borough.

Little background: 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 way too often.

The 24-hour average Wednesday was 0.008 ppm, exceeding Pennsylvania’s limit of 0.005 ppm, according to preliminary data. There have also been 12 such H2S exceedances at ACHD’s air quality monitor in North Braddock.

“We think it’s important to remember that while U.S. Steel has suggested area sewage treatment plants are to blame for the Mon Valley’s H2S problem, its Clairton Coke Works was the lead emitter of hydrogen sulfide in Pennsylvania every year from 2010 to 2019,” GASP Executive Director Patrick Campbell said. “While past results certainly aren’t a guarantee of future performance, we have no reason to doubt this trend has continued.”

We know we might sound like a broken record, but GASP is AGAIN calling on ACHD to publicly address the exceedances, what’s causing them, and what’s being done to stop them from happening in the future.

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