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floorings, floor sealers and polishers, plasters, light alloys and plastic building materials,
fire retardants, concrete, slates, asphalts and bitumen felts. In addition to laboratory
tests, small scale practical trials under normal conditions of use are frequently made
and sometimes accelerated weathering tests are employed to assess the value of articles
intended for external use. Defects are also investigated on site.
The importance of testing clays and ground waters from building sites has increased
with the increased use of high blocks of flats in housing schemes. The deep concrete
foundations required may be in contact with moist soil or ground water when the
sulphates normally present in London clay which can weaken Portland cement concrete
may attack them. Estimation of the sulphate content in the soil determines the
appropriate cement to use to resist attack by sulphate in excessive concentrations.
Air pollution
The Council has co-operated for many years with the Department of Scientific and
Industrial Research in investigating the incidence of air pollution. Regular observations
are made at 20 sites, which include seven parks, six ambulance stations, Kew
Observatory, the Science Museum, and the grounds of a hospital at Godalming.
The records of air pollution obtained at these sites are reported to the Fuel Research
Station for collation with those of other authorities and publication. They are also
being used by the statistical section of this department in a continuing investigation of
their relationship with mortality and morbidity.
The amounts of smoke and sulphur dioxide averaged over the County as a whole
showed a small improvement as compared with the two previous years, despite a
severe fog in December which raised the average for that month to an unusually high
figure. The reduction was more marked in the case of smoke than sulphur dioxide.
The summer figures were normal, and the improvement was attributable to mild
weather early in the year with consequent smaller coal consumption. Measured in the
standard units, the ratio of smoke to sulphur dioxide showed the usual annual swing
from about 4-2 in the winter to 2-6 in summer, reflecting the summer reduction in the
proportion of coal consumed domestically. The winter level of smoke was about
four and a half times, and sulphur dioxide three times, the summer level.
By a standing agreement with the Ministries concerned, the Scientific Adviser or
his deputy accompanied the Chief Alkali Inspector of the Ministry of Housing and
Local Government on visits of inspection to test the efficiency of the flue gas working
plants at Battersea and Bankside Power Stations.
The widespread applications of nuclear science have drawn attention to the risks
of environmental contamination by radioactive matter, and during the year further
progress was made in developing techniques of measurement. Such contamination can
arise from tests of nuclear explosives, reactor accidents, or unguarded use of the radioisotopes
now being widely utilised in hospitals, research laboratories and industry.
In the days immediately following the Windscale accident of 10th October, airborne
radioactive matter from this source was detected in the atmosphere, and it was
estimated that the amount inhaled by the average Londoner was about 0-01 micro-curie.
The amount of radio-iodine present in milk was an important factor on this occasion,
and this was found in some samples of milk delivered in the London area to reach, but
not exceed, 0-01 micro-curie per litre. This concentration was one-tenth that at which
milk was rejected in Cumberland. Through the co-operation of medical officers of
other local authorities, estimates were made of the degree of contamination which had
prevailed in other representative areas throughout the country, the material for examination
being on filter papers used for the routine determination of smoke in the atmosphere.
The general conclusion was that, apart from the areas in which restrictions had already
been imposed, the degree of contamination was insufficient to necessitate any control
measures.
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