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dioxide at ground level. The average yearly concentration of smoke in 1969
is said to be only 25% of what it was in 1956. The fall in the concentration
of sulphur dioxide is not quite as dramatic but a decrease of 20-25% in the
ten years before 1968-69 is recorded. The figures relative to the amount of
smoke in the atmosphere are encouraging, the improved situation being
among other things, the result of a fall of 80% in the consumption of coal
for domestic use and the consequent changeover to other fuels, together
with improved methods of combustion. The reduction in the emission of
sulphur dioxide is less as the production of this pollutant is linked more
with the type and amount of fuel used than with methods of combustion.
The overall amount of fuel used is on the increase and the reduction in
concentration of sulphur dioxide at ground level is perhaps due to this
pollutant being discharged by industry at higher levels where it is more
readily dispersed. Industry is the greatest user of fuels with a high sulphur
content, while gas and electricity which are sulphur free are used more by
the domestic consumer.
The measurements taken in Harrow show similar trends to those for
Greater London.
The following points from the reports are worthy of note:-
1. 80.1% of premises in Greater London are affected by Smoke
Control Orders. (30th September, 1970).
2. The reduction of smoke concentration in Central London has
increased the duration of sunshine in Central London (during the
winter months) by about 50 per cent in ten years.
3. The frequency and intensity of fog appears to have decreased in
step with the progress of smoke control and no major fog has been
reported in London since 1962.
4. The increase in sunshine and reduction of fog has led to a dramatic
increase in visibility in London. From a suitable vantage point, on
an average winter day, a distance of four miles can be seen
compared with 1.4 miles in 1958.
5. The Medical Research Council have said that the improvement
of visibility and cleanliness now apparent in London have contributed
to the wellbeing of the Community. Also that there are
encouraging signs that the acute effects of air pollution on the
incidence and severity of chronic respiratory diseases previously
observed are now less evident.
6. It is recorded that Londoners can now grow many more plant
types successfully than 10 years ago and that 138 species of birds
double the number 10 years ago can now be seen.
Smoke Control—Progress during 1970
One Smoke Control Order came into operation during the year,
bringing the total of operative Orders up to twenty. An area of 5, 788 acres
with 37,369 premises, including 34,881 dwellings is now affected and this
represents approximately 50% of the dwellings in the Borough.