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Rotten Egg Stench & Poor Air Quality Return to Mon Valley

Local residents took to CMU CREATE Lab’s Smell PGH app Monday morning to sound off about poor air quality and its associated stench, conditions they said caused physical symptoms like itchy eyes, burning throats, and headaches.

Although concerns persist about potential local impacts from the East Palestine railroad derailment, this most recent spate of bad air quality appears to us to be centered in the Mon Valley and follows a pattern we’ve seen too many times before: high levels of fine particulate matter (PM2.5), hydrogen sulfide (H2S, which has a tell-tale rotten egg odor) and sulfur dioxide (SO2) building in the overnight hours.

Concentrations of H2S at Allegheny County Health Department’s (ACHD’s) air quality monitors in Liberty and North Braddock boroughs exceeded the state’s 24-hour average standard of 0.005 ppm this morning shortly after midnight. Exceedances of this standard also occurred several days last week.

A quick word about H2S: It’s a colorless gas recognizable by its rotten egg odor and the concentrations we see in the Mon Valley can cause irritation to the eyes, nose, or throat as well as headaches, poor memory, tiredness, and balance problems. It may also cause difficulty in breathing for some asthmatics, according to the Agency for Toxic Substances and Disease Registry.

In the overnight hours, there were also exceedances of the national health-based standard for SO2 at ACHD’s air quality monitor North Braddock. The standard is an hourly level of 75 parts per billion (ppb); ACHD reported levels of 83 ppb and 97 ppb Sunday and Monday.

“At a time when the public is understandably on high alert when it comes to air quality because of the horrific rail crash in East Palestine, we can’t overstate how important it is for our local health officials to help residents understand our local conditions,” GASP Executive Director Patrick Campbell said. “We’ve been urging the department to ramp up its public communications around air quality issues, and while we have seen some uptick, GASP is again calling on ACHD to provide proactive and robust public communications so residents are better equipped with the information they need to mitigate health impacts.”

Editor's Note: For those who'd like to take a deeper dive into the data, we graphed the PM2.5 and H2S concentrations. Check it out:

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