One of the most shameful chapters in environmental history occurred on October 30 and 31, 1948, in the industrial town of Donora in Washington County, Pennsylvania. The 14,000 residents were mostly supported by steel mills, which found the location by the Monongahela River just 30 miles (48 kilometers) from Pittsburgh to be ideal. The mills provided good-paying jobs, but the blast furnaces they used produced massive quantities of soot, sulfur dioxide, and other pollutants. In addition, the town was home to a zinc smelting plant and a sulfuric acid plant. As if that weren’t enough, the natural climate of the town made foggy weather a regular occurrence. The industry combined with the weather during a horrible Halloween season in 1948, creating such thick, brown air that it was nearly impossible to see where one was going. Five hundred of the residents fell ill from various respiratory problems and 22 people died (17 from complications from asthma or heart disease, and two from tuberculosis aggravated by the filthy air).