When the Fog Rolled Into Town, 20 People Suffocated to Death. What Made the Air So Deadly?

Posted April 22, 2026
  • At the tail-end of October 1948, the Pennsylvania town of Donora experienced a deadly smog event that eventually led to the deaths of 20 people and the sickening of thousands more.
  • The smog—generated by the smokestacks at the American Steel and Wire plant and the Donora Zinc Works, and exacerbated by local weather and geography—contained traces of hydrogen fluoride, carbon monoxide, nitrogen dioxide, and heavy metals.
  • The tragedy was one of the instigating events that led to the eventual passage of the Clean Air Act in 1970.

https://www.popularmechanics.com/science/health/a71075916/donora-fog-1948/