View report page

44
It is necessary to appreciate that the inferences to
be drawn from this work must be limited in their application to
Hampstead. All four types of apparatus are liable to casual
error - it has been found that deposit gauges placed 50 yards
apart show sensible variations in results and, in any case, only
purport to indicate conditions in their immediate locality. The
Lead peroxide gauge at Barrow Hill, for example, only shows the
activity of sulphur dioxide in the air at Barrow Hill Reservoir
and not in Hampstead generally.
The whole purpose of the work is one of collaboration
with the Fuel Research Department of the Department of Scientific
and Industrial Research, where results from local authorities and
other co-operating bodies throughout the country are received,
collated and analysed. The Fuel Research Station have estimated
that a long period of observation, preferably 5 years, is needed
before reliable conclusions can be drawn about the average level
of pollution or about the rate at which it is produced.
However, now that a second year of this work has been
completed it is reasonable to indicate certain trends.
From the deposit gauge readings it can be shown that
during the year the amount of foreign matter falling from the
air on to Hampstead is only three-quarters of the average figure
for the Metropolitan area as a whole. This might reasonably be
expected in view of the absence of power stations and heavier
industry in this Borough. On the other hand, it is obvious that
favourable wind conditions do bring air pollution to the Borough
and the readings at Barrow Hill Reservoir reflect the proximity of
the heavy steam locomotive depot at Chalk Farm.
The following tables represent part of the information
obtained from measurement of suspended impurities in the air by
means of the continuous filter. It will be seen that the average
contamination is notably and consistently less in the summer
months than in the winter, due mainly, of course, to reduced domestic
heating.
The two peaks in Table I occurred in conditions of
moderately bad fog on 20th January and 50th November, 1955,and
the intention of Table II is to illustrate the relative state of
impurity of the air we breathe in a winter month.