The Donora Smog of Nineteen Forty-Eight

On October twenty-seventh, nineteen forty-eight, a temperature inversion settled over Donora, Pennsylvania, a mill town on the Monongahela River about twenty-four miles southeast of Pittsburgh. Cold air trapped warm air against the valley floor, and the warm air was full of what the mills had put into it: sulfuric acid, nitrogen dioxide, fluorine compounds, and heavy metals from the American Steel and Wire plant and the Donora Zinc works.

The smog built for five days. It was yellowish and acrid and it smelled wrong. By Friday, October twenty-ninth, people in Donora were being carried to the hospital. The fire station ran out of oxygen equipment. Livestock died in their pens. The event note: the death toll in historical accounts ranges from twenty to twenty-six immediate deaths, with some sources citing up to fifty additional respiratory deaths in the following month; the exact figure is disputed but the scale is not.

Twenty people died in those five days, nearly all of them from respiratory failure. Six thousand of Donora's fourteen thousand residents suffered serious health effects. It rained on Sunday, October thirty-first, and the smog finally cleared.

No one was prosecuted. The courts later found the smog to be an act of God. The company paid small settlements to some families. The zinc works continued operating.

What changed was political attention. The Donora disaster, combined with Pittsburgh's own smoke-control experience, built the national case for federal air quality regulation. It became a founding event in the American environmental movement, a moment that demonstrated that industrial air pollution could kill people in their own homes, in a matter of days, in a peaceful American town. The Clean Air Act of nineteen sixty-three traces a direct line to that October weekend in Donora.