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increased in volume and complexity over recent years. About half of the samples
examined were submitted by metropolitan boroughs, and of 2,648 samples examined,
551 were considered to contravene the Act.
Following the examination of unsatisfactory samples, officers of the Scientific Branch
and of the Chief Engineer's Department usually visit the premises to discuss with the
occupiers the problems involved in treating the discharges. A similar procedure is
followed when consideration is given to applications for permission to make new
discharges where standards have to be prescribed.
Safety in sewers
Regular examination of inflammable-gas detector lamps of the expanding metal spiral
type and those based on selective diffusion is made to ensure that all lamps are in good
order and advice is given as required on the use of self-contained oxygen respirators.
Experiments have continued on methods of improving sewer ventilation.
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, and the Science Museum.
The records of air pollution obtained at these sites were again 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 average concentration of sulphur dioxide for the year remained at the same
level as in previous years, but in the case of smoke the figures show a small decrease of
10 to 20 per cent, during the last two years, both in summer and winter. The reduction
in the ratio of smoke to sulphur dioxide may be indicative of a general improvement
in the efficiency of fuel consumption and it will be of great interest to see if the trend
continues in future years.
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 washing
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 study
was made of the 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. A continuous record
was maintained of the amount of airborne radioactivity, and this indicated the fluctuation
in the amount of fall-out resulting from two major periods of testing in the spring
and autumn.
The air in the Council's vehicular tunnels under the Thames was examined weekly
in order to ensure that forced ventilation gave an adequate dilution of exhaust gases.
Carbon monoxide was kept within the specified limit on most occasions at both
Blackwall and Rotherhithe tunnels, but the amount of black suspended matter showed a
continued tendency to increase in comparison with previous years. This change is
attributable to the larger proportion of diesel-engined heavy vehicles now in use, which
can be a prolific source of smoke unless carefully maintained and properly driven. The
amount of carbon monoxide produced by the diesel engine is, however, relatively low.
Water supplies
Care is taken to ensure that the water supplies to Council establishments are of satisfactory
quality. In the majority of cases water is taken from a public supply, but
15 residential schools and other premises draw water from private wells. In these cases
the supply is chlorinated before use by means of automatic dosing apparatus and the
water supply is regularly examined.