AdvertisementSmog Deaths In 1948 Led To Clean Air Laws03:38Download AudioResumeApril 22, 2009Ann MurrayfacebookEmailThe mill town of Donora, Pa., seen Jan. 1, 1948. On Oct. 27 of that year, a smoky, lethal smog killed 20 people. The air was polluted by local steel plants, railroad yards and zinc works. (Time & Life Pictures/Getty Images)
