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101
The technical problems of pollution of the air by smoke have been
largely solved, so that by the progressive introduction of smoke control
areas and by other means a comparatively smokeless atmosphere should be
achieved in the Greater London area by the early 1970s.
The other main pollutant, sulphur dioxide, about which there has
lately been some publicity, cannot be dealt with so easily. It was
recognised when the Clean Air Act was passed in 1956 that there were
no satisfactory means available of reducing sulphur dioxide emissions
from chimneys at reasonable cost, but provision was made in that Act
for control over the heights of new industrial chimneys. This control
has been reinforced by the introduction of the Memorandum on Chimney
Heights, which gives a method of calculation based on a maximum permissible
ground level concentration of sulphur dioxide. It has been found possible
in this way to restrict the amount of sulphur dioxide reaching ground
level.
Owing to higher standards of heating now expected by the public,
and the great increase in energy requirements by industry, much more fuel
is being consumed and the emission of sulphur dioxide from chimneys has,
in this area, nearly doubled in the last ten years. However, this has not
been accompanied by any measurable increase in the average sulphur dioxide
concentration at ground level. Sulphur dioxide is a gas which disperses
upwards three times more rapidly than smoke (which consists of small solid
particles) so that the policy of increasing chimney heights is justified
and is proving useful in practice.
A close watch is being kept on the problem locally and measurements
of smoke and sulphur dioxide concentrations are taken daily at four sites
in the Borough. Observations have not been taken for a long enough period
to estimate the extent of any change. It must be emphasised that records
over an extended time are necessary to cancel the effects of climatic
conditions. In London, however, there has been a dramatic reduction in the
amount of smoke recorded at 24 sites. This has taken place during a period
when the consumption of domestic coal has been reduced from 36 million tons
to less than l½ million tons and the consumption of oil for domestic
purposes rose from 3,000 to 186,000 tons.
The present increased rate of conversion of domestic solid fuel grates
to gas room heaters is an encouraging trend which will do much to reduce
low level sulphur dioxide as will also the greater use of electricity and
to a lesser extent the conversion of open grates to the more efficient
solid fuel room heaters. A tightening of the law on chimney heights would
be of great value for at present there is no legal control over the
heights of chimneys for flats, offices and shops.
Air Pollution complaints. There were 58 complaints from the public
about nuisance from smoke and grit; 33 of these concerned bonfires, 14
smoke from factory chimneys, 8 smoking domestic chimneys and 3 concerned
smut emissions.