ABSTRACT
Air pollution episodes are characterized by signicant short-term increases in atmospheric pollutant concentrations above normal daily levels. Episodes vary from those that pose relatively limited public health concern to those more extreme. Extreme air pollution episodes were reported for the Meuse Valley, Belgium, in 1930; Donora, PA, and the Monongehela River Valley in 1948; and London in 1952. In each of these cases, a persistent (3-6 days) thermal inversion combined with signicant industrial and, in the case of London, domestic pollutant emissions resulted in high ground-level concentrations that caused acute illness and, in some cases, death in exposed populations.
