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Pennsylvania: Deadly Washington County Halloween Smog Sickened 5,000
Donora, PA – A deadly Halloween week smog disaster that killed 20 people and sickened more than 5,000 residents in Washington County, Pennsylvania, is being remembered 78 years later for helping chang
By Mason Reid · 2026-10-28T10:07:02.112Z
Donora, PA – A deadly Halloween week smog disaster that killed 20 people and sickened more than 5,000 residents in Washington County, Pennsylvania, is being remembered 78 years later for helping change America's air pollution laws.
According to the National Weather Service in Pittsburgh, the Donora Smog Disaster unfolded October 26 31, 1948, when a thick cloud of toxic industrial pollution became trapped over the small community southeast of Pittsburgh.
What began as unusually dense fog quickly turned into a public health catastrophe.
Industrial emissions from nearby zinc and steel operations accumulated beneath a temperature inversion, trapping dangerous pollutants close to the ground for several days.
By Halloween weekend, visibility had deteriorated so dramatically that people attending Donora's Halloween parade could reportedly barely see a few feet in front of them.
But the greatest danger was invisible.
Thousands of residents began experiencing breathing difficulties as the polluted air overwhelmed the community. Elderly residents and people with existing respiratory conditions were especially vulnerable.
More than 5,000 people became ill, and 20 ultimately died.
On November 1, 1948, The Pittsburgh Press published the alarming headline "DONORA SMOG DEATHS PROBED," initially reporting 19 fatalities as investigators examined the mysterious deaths.
The disaster eventually became a turning point in American environmental history.
Public outrage and growing awareness of industrial pollution helped drive demands for stronger government oversight of air quality.
The tragedy contributed to the national movement that eventually produced the Air Pollution Control Act of 1955 and the Clean Air Act of 1963, followed by major federal protections in 1970.
Now, as Pennsylvania marks the disaster's 78th anniversary, the National Weather Service is reminding residents of the tragedy that unfolded during Halloween week.
Nearly eight decades later, Donora remains a powerful reminder of how deadly polluted air can become — and how one Pennsylvania community helped change environmental protections across America.