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Extreme_Qwerty OP t1_j1xvzux wrote

Fine particulate matter (PM 2.5) commonly comes from industrial sites, car exhaust and chemical reactions in the atmosphere. The particles can lodge in the lungs and bloodstream, causing respiratory complications.

During winter, when air is warmer in the atmosphere than at the surface, temperature inversions can occur.

An inversion happens when the warmer air acts like a lid above the cooler air underneath, preventing pollutants from rising and dispersing, trapping them at breathing level.

Inversions are strongest in the winter months when pollution from vehicle exhaust, industrial sites and wood burning can fester near the ground, leading to poor air quality.

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sintactacle t1_j1z1rmo wrote

>temperature inversions

Bingo! and the most famous inversion event happened in Western Pennsylvania south of Pittsburgh in Denora.

https://pabook.libraries.psu.edu/literary-cultural-heritage-map-pa/feature-articles/cloud-silver-lining-killer-smog-donora-1948

Inversions are definitely a thing in the Southeast of the state. I used to commute through Lancaster and Lebanon counties along 322 and on still winter days, you would see the smoke from farms burning trash rise up undisturbed vertically to a point and then spread out horizontally as if it was trapped by a giant pane of glass.

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