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ATMOSPHERIC POLLUTION - MOTOR VEHICLE EXHAUSTS - LEAD
This report follows a question at Council by Councillor E Richards,
in reply to which the Chairman of the Health Committee agreed to a
referral to the Health Committee.
Lead is found in the atmosphere in inorganic form. Apart from the
dust around old smelting works and special cases such as the
burning of car batteries, the main source of this pollutant is the
combustion of organic lead compounds which are commonly added to
petrol as 'anti knock' agents.
Lead is readily absorbed into the blood stream when inhaled and
less readily when eaten. It is deposited in all organs but
particularly bones.
A normal acceptable blood level is 30 microgrammes/lOO ml but in
industry levels of up to 60/100 ml are accepted with a maximum
allowable concentration of 80/100 ml of blood. Symptoms of
poisoning arise at blood levels above 80 per 100 ml.
Cn 21 December 1971, Sir George Godber, Chief Medical Officer to
the Department of Health and Social Security, wrote to all Medical
Officers of Health about possible hazards to health from excessive
amounts of lead in food, the atmosphere, water and soil. The letter
followed a discussion by a group of experts on the available.
information of the hazards in Britain.
With regard to lead in the atmosphere, he reports that it is in
extremely small concentrations and the only reason for giving it
special attention is that, inhaled, pollutants may be more completely
absorbed than the same pollutants after being eaten. Investigations
amongst persons specially exposed to atmoshperes affected by
heavy motor traffic show no evidence of excessive amounts of lead
in the blood. Some recent investigations suggest that lead derived
from the combustion of petrols with added lead is firmly attached
to carbon particles of a sufficient size to explain why excessive
absorption does not take place. The expert group did not think
there was a general hazard from this source at the present levels
of emission.
He also reports on the possibility of high concentrations of lead
in dust and soil near to old lead smelters in one area of East
London. On three occasions outbreaks of lead poisoning have been
reported amongst children exposed at home to excessive
concentrations of lead in dust and perhaps in fumes from burning
old battery cases.
Whilst there is no evidence directly obtained on the level of lead
contamination in the atmosphere of the Borough of Lewisham, a
certain amount of corroborative evidence is available from the
London area to confirm the Chief Medical Officer's opinion. The
conditions which produce the worst pollution by vehicle exhausts are;
calm weather, high traffic density congestion (causing stop-go
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