The worst single incident of air pollution to occur in the US occurred in Donora, Pennsylvania in late October, 1948, when 20 people died and over 7,000 were injured.
最严重的单次污染事件为1948年10月美国宾夕法尼亚州多诺拉镇事故，导致20人死亡，超过7,000人受伤。