Quenching and smoke at Clairton Coke Works during inversion, 15 May 2021 (photo by Mark Dixon BlueLens via Flickr Creative Commons license)

15 October 2025. More on the subject of wind.

Though Pittsburgh’s air has improved since the Smoky City days, we still have heavy industry and unhealthy air too frequently. The rotten egg smell of sulfur lingers when there’s a temperature inversion, and since Pittsburgh averages 157 inversion days per year it’s likely there’s bad air somewhere here almost half the time. But not everyone smells it. It depends on where the plume goes, and that depends on the surface wind or lack thereof.

After CMU’s CREATE Lab published the SmellPGH app in 2016 for crowd-sourced bad air reports, they went on to develop the PlumePGH website in 2021 that shows where the bad air goes. I learned about PlumePGH in a Public Source article last week.

This two minute video explains how it works showing air movements on 10 December 2020. Back then the Cheswick power plant (orange plume) was still in operation; it closed on 31 March 2022.

To whet your appetite for the PlumePGH website, here are still shots from a recent bad air day on Saturday 4 October 2025. A screenshot of the SmellPGH map on 4 October shows that the air was really awful and a lot of people noticed it.

Selected screenshots from PlumePGH on the same day shows 3 plumes. U.S. Steel’s …

• Clairton Coke Works (Clairton PA) in purple
• Irvin Works (West Mifflin PA) in yellow
• Edgar Thomson Works (Braddock PA) in blue-green.

At 3:48am the wind was from the south. All 3 plumes intermingled as they headed north.

screenshot from Plume PGH timelapse video of 2025-10-04

Around noon the wind died and a lot of people were unhappy in the river valleys.

screenshot from Plume PGH timelapse video of 2025-10-04

At 5:35pm the wind picked up out of the southeast and a whole new set of folks smelled rotten eggs.

screenshot from Plume PGH timelapse video of 2025-10-04

Click this link to see the whole Plume PGH timelapse video for 2025-10-04.

Visit the PlumePGH website for more information.