In early October of 1948, the U.S. Steel plant and the Donora Zinc Works were working away, and most of the inhabitants of Donora were working with them. By November seventy people were dead and thousands more were sick. Why?
Donora, Pennsylvania was a working town, filled with factories and busy producing materials like zinc and steel. On the evening of October 26, something happened. For the next six days the town was locked down under a smog that ended up killing seventy people.
Something called an inversion layer settled over Donora. Usually, the heat and atmospheric pressure near the Earth heats up the lower atmosphere, like a fire heats up the air directly above it. When the air heats it expands, becoming less dense, and rises upwards until it cools. The vacuum created by the air is filled with new air, and a fresh supply of oxygen. This keeps both fires and people alive.
An inversion layer happens, generally in the winter, when the air near the ground stays cooler than the air above it. It doesn't expand, and can't rise. Whatever is released into the air, whether carbon dioxide from human breath or industrial pollutants from factories, stays right were it is. As the factories kept going, the people of Donora were slowly poisoned by the cloud that settled over them. Their lungs were burned with sulfur and their red blood cells were hijacked by carbon monoxide.
It wasn't hard to see the problem. The first sign came when people attending a football game couldn't see the players on the field. Then they couldn't see well enough to drive home. Eventually, people couldn't see their hands in front of their own faces. Some people couldn't see because the sulfur burned their eyes. Over the next week, people smothered to death, were poisoned, and suffered permanent damage to their lungs. Twenty died during the week, fifty afterwards, and hundreds suffered health problems for the rest of their lives.
Both U.S. Steel and the other companies in town conspired with the U.S. Public Health Service to keep the facts from the public. Their part in the death of seventy people and the sickness of 6,300 thousand wasn't revealed until the 1990s.
Image: German Federal Archives