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ENVIRON MENTAL HEALTH
areas will come into operation in August 1973 and August 1974. It is hoped that the final smoke
control area will come into operation in 1975.
Industry has been steadily changing over from coal-fired boilers to oil-fired plant with the consequent
reduction in smoke and particularly in grit and dust emission. There has also been an appreciable
trend in local industry towards the use of lighter and more refined oil which has a higher calorific
heating value and a lower sulphur content than the heavier grades of fuel oil. In the last few years
some large industries have changed over to natural gas and there is every indication that this trend will
increase — and this, too, will have an appreciable effect in reducing pollution. In a survey of the
boiler plant of 220 local industrial premises it was found that 77% used oil, 11% gas, 4% coal and 8%
other fuels.
Pollution from
lead
Tetra-ethyl lead is added to petrol as an anti-knock agent to prevent pinking and increase engine
efficiency in motor vehicles. During the year an instrument was installed at a site alongside the North
Circular Road to measure the amount of lead in the air. The method used was to draw a measured
amount of air through a filter paper and measure the amount of lead in the stain on the paper, the
filter papers being changed weekly. These measurements taken over a period of several months
showed that the lead content varied between one microgramme per cubic metre and 3.6 microgrammes
per cubic metre. These levels are typical of measurements taken in other urban areas where
there is heavy traffic.
A second instrument was set up to measure lead emissions from a local factory where the recovery of
lead from scrap was undertaken. The lead was emitted in the form of fume from a low chimney and
in the form of dust from fine particulate matter stored for further processing. Before being discharged
into the atmosphere, the fume was passed through a filter to remove lead and dust, and regular
samples of the flue gas were taken by an inspector of the Department of the Environment to ascertain
that emissions of lead did not exceed the standards laid down by the Department.
The measurements taken by this second instrument, which was sited close to the chimney outlet,
showed that the levels of lead in the air were far below the amounts permitted by the Department of
Trade and Industry for atmospheres inside factories.
Many samples of roadway dust were taken around factories where lead is used in quantity, and all but
one were satisfactory. One set of samples taken near the gates of a factory showed that lead levels in
the roadway dust were higher than elsewhere. Immediate steps were taken to have the roadways
cleansed and precautions taken to ensure that no excess dust containing lead was transmitted outside
the factory.
Car exhausts
A series of measurements of nitric oxide and nitrogen dioxide in the air from motor car exhausts is
being carried out on a site alongside the North Circular Road. See Table (29).
Food and drugs
Food and Drugs
Act 1955
The Food and Drugs Act 1955 and regulations made under the Act deal with the processing and
selling of food and drugs for human consumption.
In July, the Foods Standards Committee published its report on the Date Marking of Food, in which
legislation is proposed, after a period of three years, to introduce a system of "open date" marking
for pre-packed foods.
Composition and
labelling
Six hundred and sixty-five samples of food and drugs were submitted to the public analyst and 130
samples of milk were examined in the Department's own laboratory, representing a sampling rate of
three per 1,000 of the population. All samples of milk were satisfactory, but the public analyst
reported adversely on 124 samples of food: 96 were of packaged foods incorrectly labelled, and 28
were of inferior quality or unfit. In one case, both labelling infringement and unsatisfactory conditions
were found.
Advice on the Labelling of Food Regulations 1970 was given during the year to manufacturers and
importers to enable arrangements to be made for their new labels to comply with these Regulations.
Under the present legislation imported foods show the greatest number of contraventions in relation
to labelling.
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