Air Sickness

On Oct. 26, 1948, a temperature inversion laid a blanket of cold, stagnant air over Donora, Pa., a tiny mill town on the Monongahela River. Over the next 5 days, the buildup of pollution cloaked the sun, sometimes restricting vision to just a few feet. Twenty people died outright and 50 more perished within a month from lingering health damage, says consulting epidemiologist Devra Davis, a former Donora resident whose own family survived the tragedy.