The Donora smog of 1948 killed 20 people and sickened 6,000, becoming one of the worst air pollution disasters in U.S. history.
Key Facts
- Date of onset
- October 27, 1948
- Deaths
- 20 people
- Sickened
- 6,000 people
- Town population
- 14,000 people
- Distance from Pittsburgh
- 24 miles
- Cause
- Hydrogen fluoride and sulfur dioxide emissions during temperature inversion
By the Numbers
Location
Cause → Event → Consequence
U.S. Steel's Donora Zinc Works and its American Steel & Wire plant emitted hydrogen fluoride and sulfur dioxide into the air. An atmospheric temperature inversion trapped these pollutants close to the ground over the mill town of Donora, Pennsylvania, situated on the Monongahela River, preventing the gases from dispersing and allowing concentrations to reach dangerous levels.
Beginning October 27, 1948, a toxic smog settled over Donora for several days. The trapped industrial emissions caused severe respiratory distress across the community of 14,000 residents. The event, later called the Donora death fog, resulted in 20 deaths and acute respiratory illness in approximately 6,000 people, nearly half the town's population.
Mortality rates in Donora remained measurably higher than in neighboring communities for at least a decade after the event. The disaster drew national attention to industrial air pollution and is widely cited as a catalyst for future environmental regulation in the United States. It is commemorated today by the Donora Smog Museum.