What was the Donora smog disaster?

The Donora smog disaster was a deadly event in 1948 where a thick blanket of smog engulfed the town of Donora, Pennsylvania, killing 20 people and affecting 43% of the population with long-term health issues.

How did the Donora smog disaster lead to environmental reforms?

The Donora smog disaster was the catalyst for the establishment of the Division of Air Pollution in Pennsylvania in 1949 and the enactment of the Clean Streams Law and statewide clean air regulations in 1965. It also led to the creation of the Environmental Protection Agency and the Clean Air Act at the federal level in 1970.

What caused the Donora smog disaster?

The Donora smog disaster was caused by pollution emitted from the American Steel and Wire plant and Donora Zinc works, which regularly released hazardous chemicals and particulate matter. Weather conditions, including a temperature inversion and weak winds, trapped the pollutants close to the ground for several days.

Home / Environment / Deadly Smog Engulfs Pennsylvania Town, Sparking Environmental Reforms

Deadly Smog Engulfs Pennsylvania Town, Sparking Environmental Reforms

30 Oct

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Summary

Smog killed 20 people in Donora, Pennsylvania in 1948
43% of the population suffered long-term health issues
Disaster led to new air pollution regulations in Pennsylvania and the U.S.

Deadly Smog Engulfs Pennsylvania Town, Sparking Environmental Reforms

In October 2025, it has been 77 years since a deadly smog event engulfed the town of Donora, Pennsylvania. From October 26-31, 1948, a thick blanket of smog descended upon the community, with activities like the high school football game and Halloween parade continuing despite the hazardous conditions.

The smog worsened over time, and doctors warned susceptible residents to leave the area. However, it was too late, as visibility made travel extremely dangerous. By the end of the event, 20 people had died in Donora and the nearby town of Webster, with an additional 43% of the population suffering from long-term health issues.

The main cause of the smog was pollution emitted by the American Steel and Wire plant and Donora Zinc works, which regularly released plumes of hazardous chemicals and particulate matter. Weather conditions, including a temperature inversion and weak winds, trapped the pollutants close to the ground for several days.