The air quality issue is likely due to an inversion, a weather event that occurs when warm air traps cooler air on the surface and prevents pollutants from escaping into the atmosphere. It can sometimes make for a thick smog in the stagnant air. Local environmental advocacy group GASP (Group Against Smog and Pollution) believes more regulations should be put in place from the Allegheny County Health Department on the industries that create pollution.
In a Nov. 9 blog post about the recent air quality issues, GASP noted that the Health Department has issued several Code Orange air quality warnings over the past week, and that the concentration of PM2.5 (particulate matter) "exceeded the federal health-based standard for the past three days in a row" at the Liberty/Clairton air quality monitor in southern Allegheny County.
"The inversion is really just exacerbating an existing air quality problem. It's concentrating the pollutants closer to the ground, but it doesn't create them," says Rachel Filippini, executive director of GASP. "We're talking mainly of pollution that's created by industry, and mobile source, and it's just being trapped closer to the ground, not able to disperse."
GASP has repeatedly called on the Health Department to create stricter regulations for "episodic air pollution," which would allow the county to put in place regulations to reduce certain industries or activities when something like an inversion occurs (Filippini notes that the recent stretch of poor air quality was forecasted in advance).
On Nov. 9, the Health Department issued a statement addressing the recent inversion and warning people to "limit their exposure" to pollution.
"At the beginning of the year, the Health Department announced a series of steps to combat poor air quality during weather-related events," reads the statement. "Those steps included a new air quality regulation aimed at emission mitigation requirements for industry operating in the county during weather-related pollution episodes and building an infrastructure to model and forecast inversion events. Although slowed by the pandemic, these actions remain a priority for the Health Department and work to implement them is ongoing."
Health Department director Debra Bogen also warned that "inversions are expected to become more frequent and last longer in the coming years" due to climate change.
GASP has also been critical of U.S. Steel, which causes a significant amount of pollution in and around Pittsburgh and has a plant in Clairton and facilities in other Mon Valley locations. Last year, after an inversion event significant enough to cancel flights around Christmas, GASP criticized the the Health Department's statement that they were making sure U.S. Steel was complying with emissions requirements.
"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," wrote Filippini in December. "They choose not to.”