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What’s within the Sky?

Wispy contrails over Pittsburgh, 15 Oct 2022, 1:40pm (photo by Kate St. John)

22 October 2022

Pittsburgh skies put on a show in mid October.

On the 15th feathery contrails were pushed by high winds at 30,000 feet. We couldn’t see them at dawn because of the lumpy clouds.

Sunrise with clouds, 15 Oct 2022, 7:20am (photo by Kate St. John)

The next day the wind dropped, a temperature inversion set in, and rotten-egg smog gathered in the Monongahela Valley, below.

Inversion shows pollution from US Steel trapped in the Mon Valley, US Steel’s Edgar Thompson Works and Kennywood in the distance, 16 October 2022, 9am (photo by Kate St. John)

Temperature inversions are typical in October and November when warm air above traps cold air at the ground, filling the valleys with haze or fog. In Pittsburgh the pollution from US Steel Clairton Coke Works is also trapped, intensifying the rotten egg smell of hydrogen sulfide (H2S) in the Monongahela Valley.

Weather or not, US Steel Clairton always emits these pollutants but the 16th’s stinky haze capped more than ten days of unusually terrible air pollution caused by USS Clairton(*). Here’s how bad it was: How Bad has Air Quality Been? H2S Was Below PA Standard For Only 3 Hours This Week. (Note: H2S level is supposed to be below the standard to keep our air clean.)

The air smelled better October 17-20 including on this beautiful morning of October 20.

Sunrise, almost clear, 20 October 2022 (photo by Kate St. John)

Yesterday was not so good. Hoping for better air.

(*) US Steel’s Clairton Coke Works is the largest coking facility in the U.S., baking coal to make coke for steel production. Coking removes coal’s impurities by turning them into gases including stinky hydrogen sulfide (H2S). In March 2022 Allegheny County Health Department reported that “Based on all available data and resources, H2S exceedances that occurred at the Liberty site during the period of Jan. 1, 2020, through March 1, 2022, can be attributed entirely to emissions originating at US Steel’s Clairton coking facility.”

(photos by Kate St. John)

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