High winds, heavy fog and a warm front caused an inversion in Pittsburgh in late December that resulted, for six days, in some of the worst air pollution in the nation.

As a result, Allegheny County health officials announced yesterday that they are taking action to counter health threats from industrial emissions when weather events such as temperature inversions trap stagnant air close to the ground.

The Health Department will develop a new air quality regulation aimed at mitigating emissions this year, says Interim Director Ronald Sugar. That could mean increased fines for industries operating during events such as the inversion that led to an air alert in Clairton and Liberty throughout Christmas week.

When such weather-related events happen, the goal is for industries to have emission-reduction plans in place that could be implemented within 24 hours of notice that a public health hazard exists, Sugar says.

“We know from research that inversions are expected to get worse with climate change. We’re seeing that firsthand here,” he says, noting that four such events occurred from 2008 to 2018, and then two happened in 2019.

“Prior to December’s inversions, the county was on track for the second year in a row, and in our history, to be in compliance with air quality standards. That accomplishment is now at risk.”

The county may still attain the Environmental Protection Agency standard, but it recently exceeded — for six consecutive days — the 24-hour standard for atmospheric particulate matter at the Liberty air monitor. Higher pollution readings also were recorded at other monitored sites from Dec. 21-26.

The Pennsylvania Department of Environmental Protection (DEP) issued an air quality alert for residents of Clairton and Liberty on Christmas Eve and Christmas Day, citing an inversion. Under its alerts, the DEP recommends that children, elderly people and those with respiratory problems limit time outside.

U.S. Steel’s Clairton Coke Works is often blamed for higher pollution in the Clairton-Liberty area, even as the facility has recently operated at a reduced production rate.

County officials believe “the increasing frequency of these temperature inversions is associated with climate change,” says Sugar. “We also recognize that industry isn’t the only contributor to poor air quality, as things like vehicle exhaust have a significant impact upon pollution. While we will continue to advocate for residents to do what they can to reduce emissions, we must also explore new regulations that would impose corrective action requirements on industry during short-term pollution events.”

He did not specify what that correction action might include. However, pending state legislation — House Bill 1752 and a companion bill in the Senate — would increase fines for facilities that exceed pollution thresholds. The bills would also require industries to notify affected communities of potential health impacts if their pollution controls are compromised.

A fire on Dec. 24, 2018, in a control room at the Clairton Coke Works plant, caused damage to the desulfurization system that led to air emissions with sulfur dioxide, a gas that can aggravate respiratory issues such as asthma and cardiovascular disease.

In addition to a new emissions mitigation regulation, the Health Department will develop a model to better forecast inversion events. “Enhanced meteorological forecasting is a key element of this strategy. The expectation is that there will also be additional public notifications that will be possible,” Sugar says.