London's Pulse: Medical Officer of Health reports 1848-1972

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London County Council 1932

[Report of the Medical Officer of Health for London County Council]

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52
The effects of varying temperatures of digestion, from 61°F. to 126°F., have
been studied as well as other variations of treatment. A considerable yield of gas
of high calorific value is obtained under very varying conditions. Chemical examination
of the changes undergone by the sludge indicate that this gas is mainly a product
of the breakdown of fat, largely from soaps, rather than cellulose. Experiments are
proceeding.
The chemist has served as a nominee of the Council on three committees of the
British Standards Association; one on the Sampling and Analysis of Coal, which
has extended its activities to include coke and has issued specifications covering the
greater part of its scope; one on standard Definitions and Tests for Fire Resistance
and Combustibility, which has issued a final report; and more recently one on
Containers for Acids and Corrosive Liquids. The chemist is chairman of three panels
of these committees. He is also a member of the Government Committee on
Atmospheric Pollution.
The systematic examination of the air in the vehicular tunnels at Blackwall and
Rotherhithe, which was commenced in 1929, was continued throughout the year,
attention again being concentrated on the morning rush hour period about 10 a.m.
British
engineering
standards and
other
committees.
Vehicular
tunnels

The following table giving the averages of all samples taken during the last three years shows clearly the great improvement produced in the atmospheric conditions in the tunnels by the new ventilating plants:—

Year.Carbon-monoxide.Fog shade.
No. of samples.Average CO content parts per 100,000.No. of results above limit.*No. of samples.Average fog shade.No. of results above limit.†
Blackwall Tunnel—
193010421.539246.23
19311049.22264.010
193210311.19254.54
Rotherhithe tunnel—
193010316.425267.316
193110319.641267.821
193210210.910256.112

* Limit for carbon-monoxide: 20 parts per 100,000.
† Limit for fog shade: 6 (i.e., 1.92 milligrammes black suspended matter per cubic metre of air).
The figures for 1930 may be taken as representing the old conditions, for the
new ventilating plant at Blackwall was completed in July, 1931, and the last instalment
of that at Rotherhithe in February, 1932. Both have, therefore, been in operation
practically throughout 1932. Since all samples were taken at about the worst
normal conditions, it is evident that the atmosphere in the tunnels has in general
been maintained in very satisfactory condition, notwithstanding the continual
increase which is taking place in the amount of motor traffic passing through them.
The question of the range of visibility is intimately connected with that of
atmospheric pollution and observations from the fléche at County Hall and from
sludge ships in the Thames estuary furnish collateral information as to the variations
of efficiency of London air as a medium for the transmission of light.
Observations of horizontal visibility in all directions continued during 1932
showed that on the whole it was higher than the average of the five preceding years.
The subjoined diagram shows the mean distance in all directions at which objects
could be distinguished at mid-day in each month of 1932 and of the preceding
quinquennium, and is self explanatory.
The range of visibility was greatest in the quadrant S.E. to S.W. and markedly
so in the summer months June, July and August, as is shown by the second diagram.
The visibility in the quadrant N.E. continues to show the improvement on the
average of the previous five years which was noted in 1931.
Visibility.