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Yet Another Air Quality Exceedance in Mon Valley, as Area (Again) Experiences Worst AQI in Nation 

Updated: Mar 25

It’s official: The Mon Valley will experience yet another air quality exceedance today according to preliminary data from the Allegheny County Health Department (ACHD).

The air was so rotten Thursday that by 6 a.m. it was numerically impossible for the North Braddock and Liberty monitors *not* to exceed the state’s 24-hour hydrogen sulfide standard of 0.005 ppm – the seventh such exceedance so far this year.

There was also another insane one-hour value (0.081 ppm) at North Braddock – which is the second-worst one-hour value since Jan. 2016 for all ACHD h2s monitors.  

Consider this: “The 0.081 ppm peak today and the 0.077 ppm peak on March 3 are the second- and fourth-highest one-hour h2s readings over the past 5 years,” GASP staff attorney Ned Mulcahy noted. “That means two of the worst four hours over the past five years have occurred in the past three weeks in North Braddock.”

GASP again is calling on ACHD to better communicate these exceedances to the public, and to make finding the source of these concerning H2S peaks a priority.

“It’s a warm spring day, but many in the Mon Valley were forced to shutter their windows Thursday morning because of what was largely described as an industrial stench,” GASP Executive Director Rachel Filippini said. “We continue to be extremely concerned about the source of these recent H2S spikes in North Braddock. It’s a question we hear from the public often when these exceedances happen, ‘Is there something going on at Edgar Thomson?’”

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