This Day in History: 1931-11-12

Belgium’s poison fog was probably just due to abnormal weather conditions, a commission reports on this day in 1931. We now know that the five-day fog killed 67 and sickened thousands in the industrial Meuse river valley Dec. 1 – 5, 1930 was due to fluorine as an ingredient in air pollution. Similar poison fogs had occurred in the Meuse valley in 1897, 1902 and 1911. Similarly well-publicized incidents would occur in the US in Donora, PA in 1948 and London in 1952, but in fact, such “smog episodes” were relatively routine.