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ATMOSPHERIC POLLUTION
The results of the measurement of air pollution by the methods recommended by the Department
of Scientific and Industrial Research are set out in the Tables which follow.
Table 1 - Deposit Gauge
Material coarse enough to settle out of the atmosphere is collected in the bowl of the gauge
and washed by rain into a large bottle. Each month the contents of the bottle are measured and
analysed. The Table gives the volume of water collected and its equivalent in inches of rain,
and it will be seen that the rainfall in 1959 was much below that of 1958 and less than the
average for the previous five years. The influence of the redevelopment of the City with its
consequent demolition and reconstruction of buildings continues to be reflected in the total
deposited matter which is much in excess of the average for the previous five years. In these
circumstances the original intention of the gauge to measure the impurity produced by the combustion
of coal and similar fuels, is of a reduced value. However, there is a connection between
the deposits of combustible matter (including tar) and the smoke emitted from chimneys. This
constituent is determined by estimating the weight of the matter which is insoluble in water but
soluble in carbon bisulphide. Smoke pollution is at its maximum in the winter heating season,
i.e. from the beginning of October to the end of March. A comparison of the weights obtained
during the five heating seasons beginning in October 1955 (which approximately corresponds with
the period of operation of the smoke abatement provisions of the City of London (Various Powers)
Act, 1954) with the previous five years beginning in October, 1950 shows that the deposits of
"Tarry matter" has decreased by some 62 per cent. This corroborates the results of the survey
of air pollution in London by members of the Department of Scientific and Industrial Research,
referred to in the last annual report, when it was concluded that the maximum reduction in smoke
pollution in the centre of the City of London was some 58 per cent, and gives added force to the
view that there is appreciable local benefit in a smokeless zone although it may be surrounded by
smoky neighbours. In the latter connection it is noted that by the end of 1958, of the five local
authorities bounding the City, with a total acreage of 6,507 , 305 acres in three boroughs were
covered by smoke control areas under the Clean Air Act, 1956. The establishment of these areas
has as its main purpose the control of smoke from domestic stoves and fireplaces burning coal,
which cause about half the smoke in the atmosphere. By the end of 1959 an additional 320 acres
in four of the boroughs was covered and by the end of 1960 it is estimated that a further 588 acres
in five boroughs will be similarly dealt with. At this rate of process it is estimated that the
target year for the completion of the phased programmes in the five areas will vary between 1965
and 1974. The area of the City of London is 678 acres.
Through the good offices of the Warren Springs Laboratory of the Department of Scientific
and Industrial Research, and with the permission of the Controller of Her Majesty's Stationery
Office, the photograph illustrates the yearly average of smoke pollution in the County of London.
It will be seen that the smoke concentration in the City of London is of the lowest order.
Table II - Smoke concentrations by the volumetric method
This method recognises the distinction to be drawn between the relatively coarse particles of
pollution deposited by their own weight, or washed down by rain - as measured by the deposit
gauge - and fine particles which remain suspended in the atmosphere. In 1959 the average concentration
of smoke varied slightly from the results obtained in 1958. Short period measurements
taken at Golden Lane during foggy weather between 2.0p.m. on the 18th until 2.0 p.m. on the 19th
February resulted in an average concentration of 109 milligrams per 100 cubic metres. On the
12th November, similar measurements between 2 and 10 p.m. recorded a concentration of 139
milligrams. The foggy weather on the 18A9th November when further short period measurements
were taken resulted in a smoke concentration of 133 parts per 100 m. parts per air.
Table HI - Sulphur measurements by the volumetric and lead peroxide methods.
All four stations showed increases in sulphur pollution by the volumetric method when compared
with 1958 and with the previous five years at Golden Lane. The results obtained by the
lead peroxide method (which determines over monthly periods the extent to which an area of 100
square centimetres is attacked by atmospheric sulphur dioxide) indicates that at both Golden
Lane and Finsbury Circus there was an increase when compared with 1958 and the averages for
the previous five years. Short period measurements taken at Golden Lane between 2.0 p.m. on
the 18th February and 2.0 p.m. on the 19th February showed an average concentration of 105 parts
per 100 million parts of air, and similar measurements between 2 and 10 p.m. on the 12th November
recorded an average concentration of 72 parts of sulphur dioxide per 100 million parts of air.
More foggy weather occurred on the 18/19th November when short period measurements resulted
in an average concentration of 83 parts of sulphur dioxide to 100 m.p.p. air.
It has been suggested that when the mean level for London attains a daily value of 200 milligrams
of black suspended matter per 100 cubic metres of air and 40 parts of sulphur dioxide per
100 million parts of air a 'smog incident' is likely to occur. Fortunately, the foggy periods when
high pollution figures were obtained were of comparatively short duration,and without atmospheric
conditions conducive to so-called 'smog incidents'.
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