Page 326 - Fundamentals of Air Pollution 3E

282 18. The Meteorological Bases of Atmospheric Pollution

persons. They attributed the deaths to the synergistic effect of fine particles
and sulfur dioxide combined. They believed that considerable sulfuric acid
mist was formed from the oxidation of sulfur dioxide, but since no measure-
ments were made, its amount was speculative.

D. Similarities of the Three Episodes
In the Meuse Valley, Donora, and London episodes, the areas were
influenced by high pressure with nearly nonexistent surface air motion.
Surface inversions caused the condensation of fog, which, once formed,
persisted throughout the day, even during midafternoon. In each case the
fog layer was relatively shallow, extending only about 100 m. The persis-
tence of the fog past the third day and the lack of any air transport out of
the region, as well as the existence of considerable emissions of pollutants,
seem to separate these episodes from more common meteorological occur-
rences. Both the Meuse Valley and Donora had topography constraining the
volume in which the pollutants were confined. This constraint apparently
resulted from the lack of any transport wind in the London 1952 episode.
Measurements of pollutant concentrations were made only in London.

E. Other Episodes
A number of somewhat less severe episodes are discussed in Goldsmith
and Friberg (6). Mention of the more important ones follows.
An air pollution episode responsible for approximately 300 excess deaths
occurred in London between November 26 and December 1,1948. Concen-
trations of smoke and sulfur dioxide were 50-70% of the values during the
1952 episode.
An accident complicated by fog, weak winds, and a surface inversion
occurred in Poza Rica, Mexico, in the early morning of November 24,1950,
when hydrogen sulfide was released from a plant for the recovery of sulfur
from natural gas. There were 22 deaths, and 320 persons were hospitalized.
In November and December 1962, a number of air pollution episodes
occurred in the Northern Hemisphere. In London a fog occurred during
the period December 3-7, with sulfur dioxide as high as during the 1952
episode, but with particulate concentrations considerably lower due to the
partial implementation of the 1956 British Clean Air Act. Excess deaths
numbered 340. High pollution levels were measured in the eastern United
States between November 27 and December 5,1962, notably in Washington,
DC, Philadelphia, New York, and Cincinnati. Between December 2 and 7
elevated pollution levels were found in Rotterdam; Hamburg, Frankfurt,
and the Ruhr area; Paris; and Prague. Pollution levels were high in Osaka
between December 7 and 10, and mortality studies, which were under way,
indicated 60 excess deaths.