If you’ve noticed a distinctive stank in and around the Mon Valley over the past week, Allegheny County Health Department (ACHD) air quality monitor data show a likely culprit: Hydrogen sulfide (H2S) concentrations that exceed Pennsylvania’s 24-hour standard.
SmellPGH users certainly noticed: Many reports poured in those days with folks complaining of an industrial, rotten-egg odor.
Our Mon Valley friends (and those who live downwind of those communities) know the H2S stench all too well: So many people have told us so many times that the rotten-egg odor is strong enough to seep through their closed windows and pungent enough to wake them from slumber.
If you’re asking yourself, “What’s the source of all that stink?” we’d like to remind folks: In 2022 ACHD published a comprehensive study analyzing potential sources of H2S that have been driving exceedances of the Pennsylvania 24-hour average H2S standard at its air quality monitor in Liberty Borough.
The 31-page study concluded:
“Based on all available data and resources, H2S exceedances that occurred at the Liberty site during the period of Jan. 1, 2020, through March 1, 2022, can be attributed entirely to emissions originating at U.S. Steel’s Clairton coking facility.”
But it should be noted: The Clairton Coke Works isn’t the *only* industrial source of the foul-smelling air pollutant - U.S. Steel’s Edgar Thomson facility in North Braddock is one, too.
Now back to recent conditions, because this past week has been a rough one: ACHD monitor data show that H2S concentrations exceeded the state limit this past Saturday, Sunday, and Monday at its air quality monitor in Liberty Borough and on Monday and Tuesday at the North Braddock location.
For those keeping count, that means there have been 58 such exceedances at the Liberty monitor so far this year and 21 more at the North Braddock monitoring station.
Note: ACHD began monitoring for H2S at the North Braddock monitoring location in 2020.
“Based on the rate of exceedances so far this year, we are on pace for 90 H2S exceedances at Liberty and 32 at North Braddock for 2023. If that pans out, that would make 2023’s numbers slightly better than 2021 but clearly worse than 2022,” GASP Executive Director Patrick Campbell said. “Because the provisions in the consent decree between ACHD and U.S. Steel were expected to stem these emissions issues, we have to ask: Why the sharp increase in H2S exceedances at the North Braddock monitor?”
Editor’s Note: A little context: The consent decree called for U.S. Steel to begin “feeding an oxidizing chemical additive or additives…into the slag pit quench water spray system, to enhance suppression of H2S emissions.” Stay tuned, GASP is investigating how - and if - U.S. Steel met the requirements of the agreement.