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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 23 outdoor baths, many for public use, and 24 indoor
baths situated in schools and institutions. A number of baths are equipped with complete
purification plant and all receive some form of chlorination treatment. Regular visits are
made to these baths by officers of the branch for inspection and testing; samples are taken
for bacteriological and chemical examination.
As an example of the efficiency of treatment, the following were the figures obtained
from 13 fully equipped public baths during the five months summer season, in which time
about 850,000 people used the baths. The minimum measured clarity was 18 feet and the
maximum was 160 feet. These baths vary from 100,000 to 1,000,000 gallons capacity and
are emptied and refilled with mains water only once a year.
Noise and acoustics
There was an increase in the amount of work done under this heading, due largely to
the growing awareness of the significance of noise in town planning.
Measurement of the existing background noise levels was completed at two-thirds 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 an additional 80 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.
Acoustics measurements were made to test sound insulation methods in blocks of flats
and also in connection with the design of ventilating systems for the new concert hall and
art gallery to be built on the South Bank.
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