This Day in History

On Oct. 29, 1948, a deadly smog hung over Donora, Pennsylvania. The smog persisted for five days and made thousands of people seriously ill. Twenty people were sickened so severely that they died.

At the time, Donora was a little town with a population of just 14,000 people, situated in a valley on the banks of Monongahela River. The small town had a zinc smelting plant and a steel mill that produced a great deal of air pollution -- including carbon monoxide, sulphuric acid and other contaminants. For years the steel mill and zinc smelting plant released these dangerous contaminants into the air of the small town.

Donora's Air Pollution Problems Started in the 1920s

In the 1920s, the zinc plant's owner paid money to the town's residents as compensation for the problems caused by the pollution, but the release of pollutants continued unchecked.

In late October 1948, beginning around the 26th of the month, a heavy fog came down over Donora. The fog trapped the pollution so it could not escape as it normally did and the valley's air filled with toxic chemicals. Very soon, doctors and hospitals in the valley were inundated with calls from suffering townspeople. The physician in charge of the town's Board of Health advised all residents with breathing issues to evacuate immediately. By the time he made this recommendation, 11 people had already died -- they were all elderly and had asthma or heart problems.

20 People Died from the Disaster

Most of the townspeople tried to evacuate but traffic jams made it hard to get out of town. Thousands of people filled Donora's hospitals. On Oct. 31, the zinc factory finally closed down its operations. On the same day, a heavy rain dispersed the contaminants. However, by the time the disaster was over, another nine people were dead, bringing the death toll to 20.

The smog disaster in Donora made national headlines. It caused air pollution to become an issue for public debate. In 1955, the Clean Air Act was passed, which has helped to keep the air clean and avoid similar catastrophes ever since.