PITTSBURGH (KDKA) — Parts of Western Pennsylvania are experiencing poor air quality due to temperature inversions increasing ground-level ozone, and it’s been stinky outside because of high hydrogen sulfide levels.

Multiple things are happening in the air at once, and it’s keeping people who care about air quality very busy this week. The Breathe Project and the Group Against Smog and Pollution are asking how can it be prevented in the future.

“We have different types of pollution happening simultaneously right now,” said Matthew Mehalik, executive director of the Breathe Project.

Over the past couple of days, the air quality hasn’t been great, and it has been smelly. H2S, hydrogen sulfide, is the stuff that smells like rotten eggs.

“Higher levels of emissions from our industrial facilities that release particles, and then part of those industrial processes, particularly in steelmaking and coke making, is the release of hydrogen sulfide,” Mehalik said.

Hydrogen sulfide exceeded the state’s 24-hour average standard in Allegheny County from Sunday through Monday. Mehalik said that’s now happened about 38 times in 2024.

Allegheny County’s Hydrogen Sulfide Dashboard for Liberty showed the highest levels in the last 12 months hit at 3 a.m. Monday.

“Those levels, in addition to the particles that came out at the same time, had our airshed as the number one worst airshed in the country,” Mehalik said.

On Tuesday, the SMELLPGH map was filled with dark red triangles, which are the highest-rated smell reports on the scale.

“It is a quality of life issue for people, especially as they are anywhere downwind of Clairton Coke Works. And so it keeps people awake at night,” said Patrick Campbell, executive director of Group Against Smog and Pollution.

Tuesday was also a Code Orange Air Quality Action Day with ozone above level 100. This type of pollution is most common in densely populated areas with more car exhaust and industrial air emissions.

Their advice for a code orange is to be aware, check the air quality levels and make changes to your day if you are in the sensitive group.

Mehalik said temperature inversions trap unhealthy air closer to the surface, and that also traps hydrogen sulfide.

“Because it’s a hot, humid air mass that traps these chemicals in the atmosphere that causes all of this,” he said.

“That’s why we get the stinky air that’s coming into the city up through the valley from steel facilities in the past day or two,” Mehalik added. 

Mehalik and Campbell said the Allegheny County Health Department has been issuing violations and fines. But they said stronger actions may be needed, like requiring industrial facility upgrades, maintenance, and pollution control technologies.

“Those kinds of actions might actually begin to move the needle on preventing these kinds of experiences during inversions because inversions don’t create pollution. They just make it worse for you and I breathing here in Pittsburgh,” Campbell said.

“We’ve got to clean up these processes and hold the people who have the negative impact accountable, so they clean it up,” Mehalik said.

In the past, U.S. Steel has been fined for high-level exceedances of air emissions standards for hydrogen sulfide at Clairton Coke Works. On Tuesday, U.S. Steel sent KDKA-TV a statement about the recent air quality and H2S levels:

“The region experienced a temperature inversion during the early part of the week. U. S. Steel followed the episode response plan mandated by the Allegheny County Health Department, as it always does during inversions. Environmental excellence is a core part of everything we do, and we will continue to monitor atmospheric conditions and respond appropriately.”

Meanwhile, Allegheny County’s Air Pollution Control Advisory Committee has a meeting on Thursday night. It will focus on a proposal to increase permit fees for companies.