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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.
There were no new test explosions in the atmosphere during 1963 but delayed fallout
from earlier large-scale tests continued to arrive and reached a maximum in the middle
of the year, when the rate of deposit of long-lived isotopes was the highest ever recorded
in London. Whilst the concentration of strontium-90 in diet was unusually high, it remained
well below the level at which any preventive action, such as selection or restriction of diet,
would have been necessary.
Other matters dealt with during the year included the use of radio-isotopes in schools
and 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. At the end of the year primary responsibility
for authorising the discharge of wastes passed to the Ministry of Housing and Local
Government.
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. Forty 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.
A new development has been the installation of learner swimming baths in primary
schools. These are maintained at about 85°F. and have a maximum depth of three feet; they
have plant for complete purification. Thirty-four of such baths have been installed and they
have proved very successful in teaching the younger children to swim.
Noise and acoustics
The analysis of the results of the noise survey of 36 square miles in central London was
completed. This has provided comprehensive information on noise levels in London and
amongst other facts has shown that, in most places in the area, the level of noise remains
fairly constant between 8 a.m. and 5 p.m. with only a very slight rise during rush hours.
The quietest hour is 3 a.m. but after 4 a.m. levels begin to rise sharply. A full report on this
work is to be submitted to the Council during 1964.
During 1963 a number of road improvements, such as conversion to one-way roads
and the widening of main roads came into use and studies were made in several areas of
the effect of forms of traffic improvements on noise.
Measurements taken in teaching rooms at several London colleges showed that the
upper limit of noise (55 dBA), which was thought acceptable by the Government Committee
on the Problems of Noise, was frequently exceeded. Ambient noise levels are now measured
when considering possible sites for the building of new schools and colleges.
Promising work on the suppression of noise from road breaking appliances was carried
out and several complaints concerning noise were investigated at the request of the Council
and some metropolitan borough councils.
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