#airqualityexceedance

Blog Against Smog

Feb 22, 2022

<UPDATED> More H2S Exceedances at Liberty, Mon Valley Residents Report Stench

Editor’s Note: This blog was updated at 10:35 a.m. Feb. 23 to include an updated H2S chart. Users of CMU CreateLab’s crowd-sourcing app SmellPG reported the usual odors – saying the pungent air that seeped in through their windows last night and this morning was reminiscent of rotten eggs. Some said it was a strong sulfur smell. Others called it “industrial.” The possible culprit could be the elevated concentrations of hydrogen sulfide that have pervaded the Mon Valley Monday

Jul 27, 2021

The Mon Valley Stinks (Literally): Sky-High H2S Concentrations Cause Air Quality Exceedances

Editor’s Note: This story was updated at 9:25 a.m. on Thursday, July 29 to include additional information about an air quality exceedance that occurred on Wednesday, July 28. The associated chart was also updated to reflect the new data. Hydrogen sulfide concentrations at Allegheny County Health Department’s air quality monitors in Liberty and North Braddock boroughs were sky-high Tuesday morning – so high that by 10 a.m. exceedances of the state’s 24-hour average standard we

Apr 19, 2021

Another Weekend, Another H2S Air Quality Exceedance for Mon Valley

The average concentration yesterday was 0.006 ppm, according to preliminary health department data. The state 24-hour standard is 0.005 ppm. The Sunday H2S exceedance was the sixth so far this month and the 13th so far this year at the Liberty monitor. Hydrogen sulfide is a colorless gas most commonly recognized by its “rotten egg” smell. This most recent exceedance comes in the wake of a Notice of Violation issued by ACHD to U.S. Steel on April 1 regarding H2S emissions. The

Apr 5, 2021

UPDATED: Several More H2S Exceedances for Mon Valley as Poor Air Quality Lingers

Editor’s Note: This story was updated at 3:51 p.m. Monday to include today’s exceedances at the Liberty and North Braddock air quality monitors. High concentrations of hydrogen sulfide (H2S) in the Mon Valley led to exceedances of the state standard on Saturday and Monday at the Allegheny County Health Department’s air quality monitoring sites in Liberty and North Braddock. For the uninitiated: Hydrogen sulfide is a colorless gas most commonly recognized by its “rotten egg” s

Mar 25, 2021

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

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 Br

Mar 12, 2021

Thursday Marked Fourth Straight Day of Hydrogen Sulfide Exceedances in the Mon Valley

The values in red denote exceedances of PA’s 24-hour H2S standard of 0.005 ppm. Thursday marked the fourth straight day of air quality exceedances in the Mon Valley, with hydrogen sulfide (H2S) concentrations again exceeding the Pennsylvania standard at Allegheny County Health Department’s Liberty monitor – the 24-hour average H2S concentration was 0.009 ppm at the Liberty monitor. The PA standard is 0.005 ppm. That means there were H2S exceedances at the Liberty air quality

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