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SMOKE POLLUTION FROM ROAD VEHICLES
Between 26th August and 17th October 1960, in conjunction with
the Warren Spring Laboratory of the Department of Scientific and
industrial Research, a survey was made of the smoke pollution due
to road traffic in Archway Road.
Sampling Points Measurements of the hourly mean concentration of
smoke at a height of 10 feet above the ground
were made at a point in the building line beside Archway Road
opposite the Highgate Underground Station; another set of measurements
of concentration at the same height were made at a point 100 yards
from the main road in the grounds of the Library in Shepherds Hill
in order to provide information on the "background" concentration
due to sources other than traffic. All measurements were made
by passing a sample of air through a white filter and measuring
the darkness of the stain produced. The figures given can therefore
be taken as relative amounts of "black smoke".
Background Concentration The background concentration of 30 micro-
grammes per cubic metre is very similar
to measurements made in neighbouring boroughs (allowing for some
difference in ventilation) and may be regarded as a true measure of
the pollution in the area. The mean pollution on weekdays (Mondays
Friday) at the Archway Road site is, however, 360 microgrammes
Per cubic metre - i. e. twelve times the background, and this additional
Pollution can only be due to traffic.
On weekdays, there are two maxima in the pollution due to
traffic between 6 a. m. and 9 a. m. and between 7 p. m. and 10 p. m.,
the highest figures being observed between 7 a. m. and 8 a. m. when
the mean concentration at Archway Road was 750 microgrammes per
cubic metre, while at the library it was only 40 microgrammes per
cubic metre.
Traffic Flow and On a Tuesday and a Sunday during the survey,
Smoke Concentration a census of road traffic was carried out at a
point near the site of the measurements and
these indicate that the variation during the day did not agree with the
variation in the number of diesel vehicles passing (which does not
vary much between 6 a.m. and 8 p.m.) The variation in concentration
of pollution agreed in fact much better with the variation in
total number of vehicles passing. This need not be taken to imply
hat all vehicles contribute equally to the pollution since the amount
smoke emitted by a diesel vehicle will be greater in periods of
traffic congestion when it is subject to frequent halts. There will
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