Mon Valley air again hits unhealthy levels

ranged from an AQI of 152 to 179. At the Lincoln monitor, readings in the “unhealthy” spectrum occurred between 10 p.m. Thursday and 6 a.m. Friday, topping out at an AQI of 176.

An AQI between 0 and 50 denotes “good” air quality. AQI from 201 to 300 is “very unhealthy,” while readings between 301 and 500 are in the “hazardous” range.

Aaron Aupperlee, a spokesman for the Health Department, said Friday the Liberty monitor would exceed the 24-hour standard for fine airborne particles — known as “PM2.5” — by the end of the day. He said air quality was expected to be much better Saturday.

Mr. Aupperlee said the Health Department didn’t issue its usual activities advisory for a bad air quality day because the state Department of Environmental Protection did not predict the PM2.5 levels would exceed the 24hour standard.

He said the county met the 24-hour standard for fine particulates last year and is on track to meet it again this year despite the frequent inversions that cause readings to spike.

Mr. Aupperlee also said the regulation subcommittee of the Health Department’s Air Quality Advisory Board met this week to review a draft of the Air Pollution Episode Rule, which includes measures to reduce air emissions and minimize the impact on public health during an inversion. U.S. Steel participated in that meeting.

Myron Arnowitt, Pennsylvania director for Clean Water Action, a national environmental organization, said the high AQI readings on a day when winds were higher than normal during an inversion indicates a significant and ongoing problem with emissions from U.S. Steel’s Clairton Coke Works and Edgar Thomson steel mill in Braddock.

Amanda Malkowski, a U.S. Steel spokeswoman, said the company was already operating at a reduced level due to lesser demand during the pandemic, and it has made a commitment to support the Health Department’s development of a way to better predict inversions and lessen their impact on nearby communities.