Donora physicians worked around the clock, treating victims as best they could against a mysterious pathogen. The Donora Board of Health set up an emergency aid station and temporary morgue in the basement of the Community Center. Volunteer firemen felt their way door to door, administering oxygen and attempting to get people help. Management at the mill refused to believe or admit that the waste they were emitting caused the problem; after all, it was the same thing they had been doing for over thirty years.
In less than three days, hundreds of people fell sick, twenty-one people were dead, along with dozens of animals. Who knows how many more followed in the weeks, months and years to come. On October 31, rains finally dispersed the killer fog, but leaving the nation in shock. The dead and sick were not only from Donora but also from the neighboring communities of Webster and Sunnyside that were down wind and across the river.
The Federal, State and Local governments, along with numerous universities and scientists, conducted an investigation. Sulfur dioxide emissions from U.S. Steel's Donora Zinc Works and its American Steel & Wire plant were frequent occurrences in Donora. What made the 1948 event more severe was a temperature inversion, in which a mass of warm, stagnant air was trapped in the valley. The pollutants in the air mixed with fog to form a thick, yellowish, acrid smog that inhibited the normal process where the sun would burn off the fog. This smog hung over Donora for five days. The sulfuric acid, nitrogen dioxide, fluorine and other poisonous gases that usually dispersed into the atmosphere were caught in the inversion and continued to accumulate until rain ended the weather pattern.
The killer fog introduced America to a new term: smog - a combination of naturally occurring fog and industrial pollution. The 1948 Donora Smog made the world aware of the dangers of unchecked pollution. The tragic and heroic events of that October weekend helped shape the environmental movement that was to follow.