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Weekend Sees Yet Another H2S Exceedance for Mon Valley

Updated: Apr 16


Concentrations of the air pollutant known by its rotten-egg odor were high enough to exceed Pennsylvania’s 24-hour average of 0.005 ppm, ending the day at 0.008 ppm.


This marks the 46th day of 2021 when H2S exceeded that standard at the Liberty monitor. There were 17 other such exceedances at ACHD’s air quality monitor in North Braddock Borough.


“The Mon Valley remains on pace to hit at least 50 H2S exceedances by the end of the year. For those who might not know, that would double the amount from 2020,” GASP Executive Director Patrick Cambell said. “County leaders like to talk about how much our air quality has improved over the years, but in many areas, Allegheny County is failing to make improvements. This is one of them.”


At this point, GASP has said it before in several dozen blogs this year but we’re going to keep saying it: Residents deserve more information and answers from the Allegheny County Health Department about what is causing the H2S issue and what it is doing to ensure that it stops.


As a reminder: An enforcement action was levied against U.S. Steel back in April for violating the state’s H2S standard and since then there have been numerous exceedances but not one word from ACHD.


“We’ve personally witnessed ACHD downplay and talk around the H2S issue at committee meetings,” Campbell said. “Where is their commitment to protecting the health of Allegheny County residents? It’s easy to discount something you don’t have to deal with personally.”


He continued:


“It’s well past time for the Allegheny County Health Department to provide the public with an update on what it is doing to get to the root of this problem. 


Editor’s Note: GASP staff charted and graphed H2S data for those who would like to take a deeper dive:



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