Air quality alert issued for Mon Valley

People who live or work in the Mon Valley may notice air pollution is worse than normal on Wednesday.

It’s being caused by high pressure building in the area that will create inversion conditions Wednesday evening, National Weather Service meteorologist Pat Herald said.

Temperature inversions are when warm air traps cold air and pollutants close to the surface, often causing bad smells like sulfur or rotten eggs in the air.

The problem was noticed Tuesday evening, when the Liberty air quality monitor began registering elevated pollution readings that continued Wednesday, according to the Allegheny County Health Department.

It prompted the health department to issue an air pollution watch Wednesday for the Mon Valley.

The health department initially queried U.S. Steel about its operations to see if there was something it was doing that would impact air quality.

U.S. Steel took its three oldest coke oven batteries offline at its Clairton coke works, the health department said.

But U.S. Steel said doing the planned maintenance on the coke batteries shouldn’t impact air quality. Officials the company’s Clairton coke works evaluated the plant and surrounding areas, and no issues were found, company spokeswoman Amanda Malkowski said.

“The process of taking batteries down for planned maintenance does not increase particulate matter in the air,” Malkowski said. “Instead, taking planned maintenance outages actually decreases emissions from the facility.”

The county expects particulate matter in the air to impede air quality for the next 24 hours, the health department said.

Older and younger people and those with respiratory problems should limit outdoor activities until the air quality improves, the health department said.

U.S. Steel has been asked to delay resuming operation of the coke batteries until the department and the mill figure out what happened.

To see real-time air quality reports from the county’s monitors, click here.

The air quality warning comes after the area’s air pollution levels have been improving this year.

In January, all eight of the county’s monitors met federal standards for the first time in two decades.

The inversion shouldn’t last as low pressure is moving in and there will be wind and a chance of rain Thursday afternoon, Herald said.

U.S. Steel is working with the health department and others to predict when inversions might occur to determine actions that can reduce pollution, Malkowski said.