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42
The most striking phenomenon of the year was the lethal fog which
occurred in London in December. Between the 5th and 8th December,
an anticyclonic system of relatively cool air became established over the
London basin, and at the same time an almost complete calm existed.
This blanket of cold air, extending some 200 to 500 feet above ground
level became overlaid by a stratum of warmer air with a defined ceiling
between the two layers. The natural fog as well as the smoke became
trapped and the whole mass was unable to ascend and little, if any,
lateral drift occurred owing to the absence of wind.
The concentrated effect on the health of the population living in
the fog bound areas was violent and most alarming.
The deaths from cardiac and respiratory diseases occurring in the
City amounted to 82 in the fortnight during which the fog occurred
against 21 deaths from these causes in the same period in 1951 and 26
in the two weeks prior to the fog.