London's Pulse: Medical Officer of Health reports 1848-1972
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Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
City of Westminster 1935
[Report of the Medical Officer of Health for Westminster, City of]
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Table LXXV.—Atmospheric Pollution—Analyses of Deposited Impurities.
| 1935. | Figures in English Tons per Square Mile. | ||||||
|---|---|---|---|---|---|---|---|
| Horseferry Road. | Mount Street. | Finsbury Park. | |||||
| Total Solids. | Sulphur SO3 | Daily Average. | Total Solids. | Sulphur. SO3 | Daily Average. | Total Solids. | |
| January | 37.07 | 5.42 | 1.19 | 24.20 | 2.01 | 0.78 | 31.21 |
| February | 34.52 | 3.09 | 1.23 | 23.49 | 2.09 | 0.84 | 48.36 |
| March | 30.34 | 1.14 | 0.98 | 20.18 | 0.62 | 0.65 | 22.45 |
| April | 36.06 | 3.11 | 1.20 | 36.75 | 3.04 | 1.22 | 37.58 |
| May | 24.74 | 2.17 | 0.79 | 26.62 | 1.57 | 0.86 | 22.86 |
| June | 26.24 | 3.44 | 0.87 | 27.55 | 2.62 | 0.92 | 26.22 |
| July | 18.33 | 1.09 | 0.59 | 18 .67 | 1.24 | 0.60 | 15.69 |
| August | 15.67 | 1.57 | 0.51 | 20.02 | 1.66 | 0.65 | 22.15 |
| September | 28.36 | 2.42 | 0.95 | 22.88 | 2.32 | 0.76 | 26.66 |
| October | 28.29 | 2.54 | 0.91 | 21.12 | 1.59 | 0.68 | 24.97 |
| November | 29.84 | 3.09 | 0.99 | 25.61 | 2.93 | 0.85 | 45. 65 |
| December | 30.15 | 4.06 | 0.97 | 25.58 | 4.15 | 0.82 | 52.71 |
(2) The quantitative estimation of suspended impurities in the air is
carried out by means of a colour standard. A measured volume of air
is drawn through a disc of filter paper, rotated at regular intervals during
every 24 hours and the colour of the resultant deposit is compared with
those on a chart of standard tints which represent the weight of dirt
per million cubic yards of air.
Chart "A" shows the amounts of suspended impurities for an average
day of 1935, together with similar curves for days in 1933 and 1934. It
will be seen that there is a peak about 10 a.m. corresponding to the initial
lighting of fires and a secondary peak in the early evening, which
corresponds with the making up of fires in restaurants, hotels, etc.
(3) Estimation of sulphur gas (as sulphur dioxide). The method
employed is that of bubbling a measured volume of air through a solution
which has an affinity for sulphur. The sulphurous impurities retained
in the solution are subsequently measured by chemical analysis.
Chart "B" indicates graphically the amount of sulphur gas correlated
with visibility, wind direction and rainfall during 1935. The code used
for the "visibility" curve is that issued by the Meteorological Office and
is as follows:—