Editor’s Note: This story was updated to include a table listing all of the H2S exceedances in Allegheny County so far this year.
Allegheny County on Nov. 4 experienced yet another air quality exceedance, with another expected today.
According to initial data from the Allegheny County Health Department, the 24-hour average concentration of hydrogen sulfide (H2S) at the Liberty monitor was .007 ppm, exceeding the state air quality standard of .005 ppm.
Another H2S exceedance is also guaranteed today: The average h2s concentration at the Liberty monitor from 12 a.m. through 11 a.m. today was 0.013 ppm, making it mathematically impossible for the 24-hour average to be less than 0.006 ppm.
It’s worth noting that data since 11 a.m. also show elevated H2S levels, which means the final 24-hour concentration at the Liberty monitor for today might be well above the 0.006 ppm state standard.
Here’s a breakdown of 2020 H2S exceedances: