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96
Air Pollution complaints.
There were 127 complaints from the public about nuisance from
smoke and grit; 81 of these concerned bonfires; 5 smoke from factorychimneys;
9 smoking domestic chimneys; 13 grit and smuts; 8 smoke
from demolition sites and 11 fumes.
Sometimes complaints about air pollution are made without
justification. A hospital chimney was alleged to be responsible for
a deposit of white powder discovered in the roof space of a house about
a mile away On investigation it was found that the powder was
flocculent and dissolved rapidly in water. Inspection of the roof
revealed that efflorescence was taking place on the underside of the
clay roof tiles and the dried powder so formed was being deposited on
the roof timbers below.
Chimney heights.
Six applications were submitted for approval of chimney heights
under the Clean Air Acts 1956 and 1968. These were approved without
modification. In a further six cases heating engineers consulted the
department about chimney designs for boilers to which Section 6 of the
1968 Act was not applicable. Suitable advice was given in these cases.
It is gratifying to be able to report the increased use of distillate
oil and natural gas in large boiler furnaces, resulting in a reduction
in sulphur dioxide emissions.
Smoke and Sulphur dioxide measurements.
Six continuously operating instruments for daily measurements of
smoke and sulphur dioxide are sited in various parts of the Borough.
Two of these are for a Department of Trade and Industry short-term
investigation of pollution at high and low levels and will cease to be
used early in 1971. The remainder are being gradually replaced by
automatic instruments which need reading only once a week. These are
being constructed by a member of our own staff. The results at the
Guildhall site since 1958 compared with average temperatures are shown
in Figure 1.
Grit and Dust.
Two deposit gauges for the monthly measurement of grit and dust
are located at Canbury Gardens and Tiffin Girls' School, Kingston upon
Thames. Although there are fluctuations in the readings from year to
year, the long-term pattern shows a slight but steady decrease in grit
fall over the Borough. The increase in 1970 for the Canbury Gardens
site (see Figure 2) was probably the result of a heavy fall of scale in