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49
CLEAN AIR ACT, 1956.
Recording of Atmospheric Pollution
The following apparatus for measuring atmospheric pollution
is used by this department:—
Volumetric Apparatus
This is installed in the Public Health Department at the Manor
House. A sample of air is being constantly drawn from outside.
It is passed through a filter paper, on which the tarry or sooty
matter (largely emanating from the chimneys of dwelling houses)
is deposited. The density of the resultant stain is read daily and
assessed with the aid of a reflectometer. The sample of air is
then passed through a chemical solution which removes sulphur
dioxide from it. This gas is the irritant but invisible factor in
aerial pollution and originates in combustion from domestic chimneys,
factories and motor vehicles. Tests are carried out each day
to calculate the amount of sulphur dioxide extracted from a known
quantity of air.
Both these constituents of pollution are well nigh absent in
the summer months, when domestic fires are not alight and the
warmth of the sun is sufficient to remove pollution by convection.
In the autumn and winter months conditions change and the level
of pollution, especially that from tarry matter, increases to a very
much higher level.
The presence of fog is then indicated by peaks in the graph.
December 1962 saw the most severe fog since the disastrous occurrence
of 1952 and the density of smoke reached was 1,720//
grammes per cubic meter on 5th December. Sulphur dioxide
mounted to 1,815// grammes and remained well above the 1,000
reading for the next two days. The only other severe fog recorded
during the period was in the first days of 1962.
Sulphur Dioxide Gauges
Two of these were installed, one on the roof of the County
Primary School, Riverside Road, Sidcup, and the other at the County
Primary Roman Catholic School, Holbeach Gardens, Lamorbey.
However, that at the former place was subjected to malicious
damage during the month of March and it was decided not to
replace the instrument. The value of these somewhat outdated
sulphur dioxide candles is marginal, as they can only be read
monthly.
The highest recording in 1962 was 3.58 milligrams S03 per
day, collected by 100 sq. cms, PbO., during December 1962 at the
Lamorbey Station, whilst the lowest reading of 0.55 milligrams
was in August at the same site.