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The first week of December was notable for an exceptional meteorological fog which
closely paralleled that of ten years ago. Calm conditions with temperature inversion
developed on 3 December and during the next four days there were periods of dense and
persistent fog when the dispersion of chimney effluents was so poor that the concentration
of pollutants at ground level increased to ten times the normal winter figures. Although
the concentration of sulphur dioxide approached that measured during the great fog of
1952 the general evidence was that smoke was appreciably less.
Environmental radioactivity
For some years the branch has undertaken experimental studies to obtain reference
data on environmental levels of ionising radiation and to determine the extent of any
additions arising from the numerous applications of nuclear science.
Matters dealt with during the year included radiological safety in the Council's dental
clinics; the safe use of radio-isotopes and X-ray apparatus in colleges; the safety of the
public at exhibitions; advice to the London Fire Brigade in assessing hazards at fires
involving radioactive matter. Several applications were made by hospital, industrial and
laboratory users of radio-isotopes for the discharge of wastes to the sewers and suitable
provisions were made.
Swimming baths
The Council has under its control three bathing ponds, 13 swimming baths for public
use and 35 swimming baths situated at schools and institutions. Thirty-eight of the baths
are equipped with complete purification plant and all the others receive some form of
chlorination treatment.
A careful check is kept on the condition of the water and regular visits are made by
officers of the branch for inspection and testing, samples being taken for bacteriological
and chemical examination. The baths with full treatment plant vary in capacity from
100,000 to 1,000,000 gallons and are emptied and refilled only once a year. During the
year 500,000 people used the baths, this being a reduction on recent years due to bad
weather. The minimum water clarity recorded was 21 feet and the maximum 200 feet.
Noise and acoustics
Measurement of the existing background noise levels was completed at nearly all of
the 500 sites selected for the London Noise Survey, which is being made in collaboration
with the Building Research Station of the Department of Scientific and Industrial Research
and the Town Planning division of the Architect's department. The Scientific branch made
measurements at additional points to obtain information about sound effects from
helicopters.
In connection with the Council's extensive road building schemes the noise of fast
moving traffic was studied; measurements were made at sites near fly-overs, inclines,
roundabouts and junctions, and where shielding has been given by shrubbery. Estimates
were made of the alteration in noise level to be expected through road widening. The
extent to which traffic noise is attenuated in high buildings was studied.
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