Mon Valley Sees 55th H2S Exceedance, Liberty-Clairton Air Quality Again Worst in Nation Friday

Updated: Sep 12

For a time this morning, AirNow.gov showed the Liberty-Clairton area as having the worst NowCast Air Quality Index (AQI) in the nation when it soared to 156.


According to the EPA, air quality in the affected area was “unhealthy,” meaning that people with heart or lung disease, older adults, children, and teens should have avoided strenuous outdoor activities, kept outdoor activities short, and considered moving physical activities indoors or rescheduling them to reduce exposure to air pollutants.

The EPA recommends that everyone else should choose less-strenuous activities (like walking instead of running) so you don’t breathe as hard, shorten the amount of time you are active outside, and be active outdoors when air quality is better.


ACHD is predicting conditions should improve this afternoon, but that air quality could again be poor overnight and early tomorrow. For those who might not be aware: ACHD publishes an air quality and air dispersion report daily. It can be viewed here.

But wait, there’s more: Levels of hydrogen sulfide (H2S) at the Allegheny County Health Department’s air quality monitor in Liberty Borough were so high this morning that an exceedance of Pennsylvania’s 24-hour air quality standard is already guaranteed. 


For those keeping track: That makes 40 H2S exceedances at the Liberty monitor so far this year. There have been 15 other such exceedances at ACHD’s air quality monitor in North Braddock in 2021.


We encourage those impacted by today’s unhealthy air quality and any associated odors to make a report to the Allegheny County Health Department.


GASP has repeatedly asked ACHD to address these continued exceedances publicly. 


“Our members use words like ‘horrific’ and ‘awful’ to describe the air on days when H2S concentrations are high,” GASP Executive Director Patrick Campbell said. “Transparency builds trust. The health department needs to step up and let residents know what it is doing to correct the issue because right now the silence is being taken for apathy.”


Here’s a chart with details related to the H2S violations so far this year:

#H2S #airpollution #H2Sexceedance #hydrogensulfide #LibertyMonitor #AlleghenyCountyHealthDepartment #ACHD #airquality

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