Marking Time highlights one of the more than 2,500 markers that have been installed throughout the state since 1914 as part of the Pennsylvania Historical Marker Program, operated by PHMC's State Historic Preservation Office.

As early as 1881, the cities of Chicago, Illinois, and Cincinnati, Ohio, had passed laws in attempts to control several types of pollution. Air pollution, however, remained an uncontrolled, unrecognized health hazard until tragedies in the twentieth century demonstrated its lethal effects. In 1930, smog covering the Meuse River Valley in Belgium sent sixty people to their graves, and in 1952 London’s black fog was responsible for approximately four thousand fatalities during a two-week period. It was the small, industrial town of Donora, Washington County, south of Pittsburgh, that gave the United States a grim lesson in the adverse effects of air pollution.

From Tuesday through Sunday, Octo­ber 26-31, 1948, an atmospheric inversion – a trapped layer of cool air below warmer air – occurred in the Monongahela River Valley. Unable to dissipate into the atmosphere, emissions of sulfur, carbon monoxide, and heavy metal dusts released by the Donora Zinc Works, a subsidiary of the U.S. Steel Corporation, began to concentrate, creating toxic conditions. Unaware of the looming threat, Donora’s residents went about their daily business. A newspaper account described a football game during which the smog was so dense the spectators could not even see the field.

In a community of fourteen thousand residents, twenty people died and thousands became ill or were hospitalized. These fatalities, and the deaths of smog victims in other countries, spawned an awareness of the deleterious effects of air pollution and prompted governments to initiate programs to monitor and control air quality. Following the tragedy in Donora, Governor James H. Duff (1883-1969) approved the creation of the Division of Air Quality within the Department of Health for research. In 1955, the United States passed the Air Pollution Control Act, granting states funds to control airborne pollutants. The Clean Air Act, passed in 1963 and amended in 1970 and again in 1990, placed the authority for air quality control at the federal level, and remains the nation’s principal air quality law. Environmental legislation passed since the smog catastrophes has improved the quality of air. While sulfur dioxide emissions measured between fifteen hundred and fifty-five hundred micrograms per cubic meter during the 1948 Donora Smog, the Clean Air Act mandates that they are to average no more than eighty micrograms per cubic meter.

The state historical marker commemorating the 1948 Donora Smog was nominated by fourteen-year-old Justin Shawley, of Donora, who had decided to not merely pass the time during a 1994 strike by his school teachers, but rather to “mark” it. His efforts ultimately culminated in the dedication of the marker on Saturday, October 28, 1995, the forty-sev­enth anniversary of the incident. The ceremony was held at the community’s municipal building, after which the marker was erected in front of the Donora Public Library.