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Air Quality Exceedances Mounting, GASP Again Calls on ACHD to Update Public on Mon Valley Pollution

Updated: Mar 28


UPDATE: There was another hydrogen sulfide exceedance at Allegheny County Health Department’s air quality monitor in Liberty Borough Monday – making 27 so far this year.


Allegheny County experienced its 26th hydrogen sulfide exceedance of the year Friday when concentrations of the colorless gas recognizable by its rotten-egg odor surpassed the state’s 24-hour-average standard at the Liberty monitor in the Mon Valley.


That makes 26 such exceedances so far in 2021. That means:


  1. There have already been more exceedances in the first half of 2021 than in all of 2020 at the Liberty air quality monitor

  2. There has been more than one exceedance per week on average in 2021 so far at Liberty air quality monitor

  3. Since March 3, there has been nearly one exceedance every four days  

But that’s not all.


“There have also been 10 exceedances so far this year at Allegheny County Health Department’s North Braddock air quality monitor, which itself is nothing to ignore considering H2S wasn’t previously even monitored there,” GASP Executive Director Rachel Filippini explained.


GASP is again asking the health department: What’s going on at U.S. Steel’s Clairton Coke Works? 


ACHD on April 1 issued a notice of violation against the company for exceedances of the hydrogen sulfide ambient air quality standard at the Liberty monitor.  That NOV covers 25 exceedances in 2020 and seven more from the first quarter of 2021. It did NOT include eight exceedances of Pennsylvania’s 24-hour H2S standard that occurred at the North Braddock air quality monitor December 2020 through March 2021.


“Since then, the health department has provided no new details related to the ongoing H2S exceedances or what actions – if any – U.S. Steel is taking to prevent more of them in the future,” Filippini said. “Residents deserve to know when they can expect a reprieve from the ongoing stench from the mill.”



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