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Four applications were submitted for approval of chimney heights
under the Clean Air Acts, 1956 and 1968, These were approved without
modification. In a further three 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. In at least two large factories fuel oil was replaced by
natural gas for boiler firings, so reducing sulphur dioxide emissions.
Smoke and Sulphur Dioxide Measurements.
Four continuously operating instruments for daily measurements of
smoke and sulphur dioxide are sited at the rear of the old Municipal
Offices, High Street,, Hew Maiden; "Alfriston", Berrylands Road,
Surbiton; Tiffin Girls' School, Richmond Road and the Guildhall,
Kingston upon Thames, Three of these are automatic instruments
constructed by a member of our own staff, which need reading only once
a week. The results at the Tiffin Girls' School site since 1958
compared with average temperatures are shown in Fig. 1. It is
pleasing to report that the measurements at this site are undertaken
by the pupils of the school and the assistance of the head mistress, staff
and pupils is gratefully acknowledged.
The increase in SO2 concentration is disappointing, but other towns
experienced similar increases in 197l/2. Records show that the weather
was distinctly colder than average for each month from April to September
1971 resulting in fires and central heating plants being operated out of
season and probably contributing to the higher SO2 figures.
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.
It can be seen from Fig. 2 that the deposits during 1972 were among
the lowest recorded since 1958.
10. RODENT AND INSECT PEST CONTROL
During the course of the year over 2,000 properties were inspected
for rodent infestation, and there was a significant increase in the number
of complaints of mice infestation. 461 complaints were also received
regarding other pests and insects. The department has produced a number
of advisory leaflets on rats and mice, squirrels, wasps and pigeons, all of
which are available upon request.