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Watchdog Report: Another Hydrogen Sulfide Exceedance – 13th of the Year – Noted Thursday

Updated: Sep 14, 2022

If you live in the Liberty-Clairton area and were greeted by a foul odor when you opened your windows or walked outside, the culprit was likely hydrogen-sulfide (H2S) – a type of air pollution that smells like rotten eggs.

According to initial Allegheny County Health Department data, the average H2S concentration was 0.015 ppm from midnight to 10 a.m. Thursday at the Liberty monitor – a level so high that it’s mathematically impossible for today’s 24-hr average NOT to exceed the state standard of 0.005 ppm.

For those keeping track, this will be the 13th such exceedance so far this year. Prior to today, the last exceedance was noted at the Liberty monitor on Saturday with an average H2S concentration of 0.006 ppm.

We also wanted to note that fine particulate matter PM2.5 was also up for a few hours early this morning at the Liberty monitor- reaching the orange, unhealthy-for-sensitive-groups range.

Editor’s Note: Want to take a deeper dive into the air quality data? We graphed it for you:

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