Wildfire smoke in Pittsburgh before sunset 16 July 2026 (photo by Kate St. John)

17 July 2026

Yesterday while I wrote about the raging wildfires in western Ontario, 1000 miles from Pittsburgh, their smoke was blowing in our direction. By 8:00am yesterday I could see it as faint haze. By sunset it had turned the sun orange. The smoke was so thick that John English did not need a filter to photograph the sun, complete with sunspot.

Sun in wildfire smoke, Homestead, PA, 16 July 2026 (photo by John English)

Since then the air has gotten worse and is dangerous for everyone.

The PurpleAir monitor network shows a large swath of hazardous air (maroon color) from Western Ontario through the Great Lakes to the Atlantic Ocean. Its path is amazingly well defined on the northern edge where you need only drive 50-60 miles to escape the smoke (green). I’ve drawn a white line at that edge. Click on the screenshot for a closeup of the white line. Click to see the live PurpleAir monitor map. Zoom in on their map to see the details.

PurpleAir map North America as of 17 July 2026, 6:42am

Because of Pittsburgh’s frequent industrial bad air, the Group Against Smog and Pollution (GASP) teamed up with six local organizations to place PurpleAir monitors in the gaps of Allegheny County’s air monitoring network. Here’s the GASP 06 monitor in West Oakland at 8:01am this morning, 17 July 2026. Find out more about the Allegheny County Community Air Monitoring Project here and see their real-time data here.

GASP 06 Monitor in Allegheny County at 17 July 2026 8:01am

Observations:

Having lived in the Mon Valley airshed, I am all too familiar with the smell of Pittsburgh’s bad air. Yesterday it I was momentarily amazed the air does not smell like sulfur.

Indoor air quality is better that outdoors, but not best. Yesterday afternoon at 4pm I turned on my air filter and found out we were in the Red Zone. I’ve left it running since.

Indoor air quality on 16 July 2026, 4pm (photo by Kate St. John)