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Thursday Marked 6 Days of PM2.5, 7 Days of H2S Exceedances at ACHD's Air Quality Monitor in Liberty

Updated: Dec 28, 2022

In addition to spiked levels of fine particulate matter, sulfur dioxide (SO2) was also elevated, hitting 71 ppb Thursday night, just shy of a NAAQS exceedance.

That’s not all: Thursday marked seven days in a row that the Liberty monitor exceeded the 0.005 ppm 24-hour hydrogen sulfide (H2S) standard.

For those who may not have been following the story: A strong weather inversion this week helped trap air pollutants closer to the ground, helping to spur the spike at the Liberty monitor. As a result, the Liberty-Clairton area appeared several times on the list of areas in the country with the worst air quality index.

The persisting poor air quality prompted the state Department of Environmental Protection (DEP) to issue Code Orange Air Quality Action Days twice this week. The Allegheny County Health Department also issued statements on Monday and Thursday alerting the public to the inversion and its potential to exacerbate air pollution events.

The department’s statements reiterated that the department was in daily contact with U.S. Steel officials, that the company’s Clairton Works and other Mon Valley Works facilities were operating under normal conditions and within their permit limits. In the message issued Thursday afternoon, ACHD officials said that while weather conditions were expected to improve, they encouraged residents to continue to make air quality complaints online.

While the Group Against Smog and Pollution (GASP) appreciates that ACHD is communicating with residents more frequently about important air quality issues that impact public health as of late, more is needed than lip service.

“Weather is obviously not a pollution-control measure,” GASP Executive Director Rachel Filippini said. “We’ve said it before and it’s worth repeating: Even when operating under normal conditions, U.S. Steel is permitted to literally emit tons of pollution every year. The company has demonstrated that it can operate at a reduced production rate when market conditions aren’t prime, which means they could choose to do so when weather conditions are poor. They choose not to.”

GASP on Friday renewed its call for ACHD to update and strengthen coke-oven regulations in an effort to reduce industrial emissions. By way of background: More stringent coke-oven regulations are important because coke-making is, among other things, a primary source of H2S in Allegheny County. In fact, U.S. Steel’s Clairton Coke Works is the largest emitter of H2S in the entire state.

By a lot.

According to the U.S. Environmental Protection Agency’s Toxic Release Inventory, Clairton Coke Works self-reported emitting about 120 tons of H2S in 2018—the most recent year for which data is available—while the self-reported emissions for all other sources in Pennsylvania combined totaled about 36.5 tons.

Editor’s Note: We graphed the ACHD air quality data for those who want to take a deeper dive into the numbers:

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