It’s Pittsburgh’s dirty little secret.
Though obviously improved immensely from the days of smoky skies when steel mills lined the rivers in all directions, Pittsburgh still has relatively unclean air, when compared to other major metros across the country.
Finally, the region’s efforts to improve its air are starting to show up in the data. According to the Allegheny County Health Department, air measured at all eight of the county’s air quality monitors has recently met federal air quality standards — for the first time ever.
The region is now in compliance with the standards for carbon monoxide, nitrogen oxide, ozone and particulate matter (annual and 24-hour).
In April, the American Lung Association’s annual 2020 State of the Air report found that the Pittsburgh-New Castle-Weirton metro area ranked 8th most polluted for year-round average levels of fine particle pollution. That ranking did note that Pittsburgh had improved in all three of its measures, including daily spikes of fine particle pollution and ozone smog.
The monitors are located in Liberty, Avalon, Lawrenceville, South Fayette, Harrison, Clairton, North Braddock and along the Parkway East.
It was really one monitor that had been keeping Allegheny County out of compliance with the Environmental Protection Agency’s (EPA) standards for many years — the monitor in Liberty, across from U.S. Steel’s Clairton Coke Works.
According to preliminary data from these monitors, the county is attaining both annual and 24-hour standards for fine particulate matter — for the first time since the EPA set the National Ambient Air Quality Standards (NAAQS) in 1999.
The EPA’s standard for particulate matter is 12 micrograms per cubic meter, averaged over three years. Data for 2020 from the Liberty monitor shows an annual average of 9.8 micrograms per cubic meter. The 9.8 number for 2020 also meets the World Health Organization’s air quality standard of 10 micrograms per cubic meter. These numbers are currently being certified for submission to the EPA for approval.
“This achievement comes after years of hard work by the Health Department, federal and state agencies and local industry to clean up the air in Allegheny County,” says Health Department Director Dr. Debra Bogen. “But we have more work to do, and the Health Department is committed to ensuring everyone in Allegheny County has clean air to breathe.”
It’s not the pandemic recession that’s doing it, either.
While there were significant decreases in road traffic, there was not a significant decrease in industrial production. The county was on track to come in below the federal standards, even without the pandemic’s drop in pollution, the Health Department notes.
In 2020, the sulfur dioxide monitor showed a record low of 44 parts per million (ppm), 31 points below the 75 ppm standard.
“The 2020 data are promising but we still have way too many days when foul odors and pollution from industrial sources make the air unhealthy to breathe,” says Rachel Filippini, executive director of GASP (Group Against Smog and Pollution). “And our most vulnerable — children, the elderly and those with heart and lung disease — suffer the most. There are still a number of large sources in the county that lack necessary air quality permits and other sources that continue to flout air quality laws.”
In 2017, the Allegheny County Health Department and the EPA levied a Notice of Violation against visible emissions and maintenance violations from U.S. Steel’s Edgar Thomson Works in Braddock. In 2018, the Health Department started a new civil penalty policy of raised fines to encourage compliance.

The Health Department is continuing multiple programs to improve air quality, ranging from increased regulations for coke oven emissions to acquiring a $5.7 million Targeted Airshed Grant to purchase seven electric buses for the Port Authority of Allegheny County.
“This is exciting news for our county and region as we meet federal air quality standards for the first time ever at all eight of our monitors,” says County Executive Rich Fitzgerald. “Acting as the EPA’s enforcement arm, the Health Department has continued to use its regulatory power to improve air quality. It’s extremely rewarding to see this measure of success.”