The Feb. 21 enforcement order, which was posted to the Allegheny County Health Department website Friday, indicates that U.S. Steel failed its emissions tests conducted on Oct. 8-11 and on Oct. 14, 2019 for fine particulate matter (PM2.5) at Clairton Coke Works C Battery.
According to the order, U.S. Steel was pumping out 12.3 pounds of pm2.5 an hour on average during that period in October. Its installation permit limits the company from emitting more than 3.4 pounds per hour of the air pollutant.
On one of those days—Oct. 14, 2019—the Liberty-Clairton area residents endured some of the worst air quality in the nation, with AQI spiking to 163 that day.
U.S. Steel was also fined for emissions issues at its Clairton Coke Works in January for which they were assessed a $743,000 fine.