On this date sixty years ago, a poisonous fog descended on the small town of Donora, Pennsylvania. An industrial community located 28 miles south of Pittsburgh, Donora’s economy depended on the American Steel and Wire Plant (a two-factory complex owned by US Steel) and the Donora Zinc Works. Although the three plants provided the livelihood for thousands of workers, air pollution had been a problem in the region since prior to World War I, as farmers reported periodic livestock deaths and crop damage. Several lawsuits were settled out of court during these years; a routine air sampling program, however, was halted in 1935.

On 26 October 1948, effluents from the town’s factories — including suphur dioxide, fluoride, carbon monoxide, and dusts from assorted heavy metals — were trapped by an air temperature inversion that swaddled Donora’s 13,000 residents in a deadly haze for five days. During an inversion, the air at ground level suddenly becomes warmer than the air above it, halting the ordinary convection currents that would ordinarily have lifted the poisonous industrial gases into the atmosphere. As the temperature inversion took place, observers reported that smoke from Donora’s three factories rolled out from the stacks and settled across the town’s rooftops like a thick, sweet-smelling blanket.

Russell Davis, driver for the Donora Fire Department, described the scene as he responded to emergency calls as townspeople began to cough up blood and lose consciousness

There never was such a fog. You couldn’t see your hand in front of your face, day or night. Hell, even inside the station the air was blue. I drove on the left side of the street with my head out the window, steering by scraping the curb. We’ve had bad fogs here before . . . Well, by God, this fog was so bad you couldn’t even get a car to idle. I’d take my foot off the accelerator and – bango! – the engine would stall. There just wasn’t any oxygen in the air. I don’t know how I kept breathing. I don’t know how anybody did. I found people laying in bed and laying on the floor. Some of them were laying there and they didn’t give a damn whether they died or not. I found some down in the basement with the furnace draft open and their head stuck inside, trying to get air that way. What I did when I got to a place was throw a sheet or a blanket over the patient and stick a cylinder of oxygen underneath and crack the valves for fifteen minutes or so. By God, that rallied them. I didn’t take any myself. What I did every time I came back to the station was have a little shot of whiskey. That seemed to help. It eased my throat. There was one funny thing about the whole thing. Nobody seemed to realize what was going on. Everybody seemed to think he was the only sick man in town.

By mid-day on October 27, eleven people had died and the Board of Health advised residents with chronic respiratory or cardiac problems to evacuate Donora. Within three days, the death count stood at eighteen; when the air inversion lifted and rain dispersed the remnants of the fog, as many as fifty additional townspeople died of lung and heart ailments. The health of hundreds more was permanently undermined by the lingering effects of the Danora fog.

Formal investigations by the United States Public Health Service were inconclusive, blaming the weather rather than the chemical effluents or the companies themselves. The PHS results were not surprising. Oscar Ewing, head of the Federal Safety Administration — where PHS was housed at the time — was formerly a top lawyer for Alcoa, which was fending off multiple lawsuits throughout the United States as a result of wartime air pollution. Although the medical symptoms in Donora were consistent with fluoride poisoning, the final report refused to single out any particular chemical for blame for the deadliest air pollution disaster in United States history.

Unfortunately for researchers, the PHS records related to the Donora Fog have been permanently misplaced or destroyed; the investigative records of US Steel, which evidently still exist, are closed to public scrutiny.