ATMOSPHERIC POLLUTION 
shear, and speed. These may in turn, after experimental work 
to determine quantitatively the amount of dilution a con- 
taminant undergoes under various meteorological conditions, 
determine how much contaminant may be released without 
nuisance or physiological harm. 
G. M. B. Dosson. As a result of much work in recent 
years, we now have a fair knowledge of the distribution of 
pollution within a town and the mechanism of its removal 
from the air at street level. On the other hand we know 
very little about the travel of the smoke cloud down wind 
from a large town though its effect is clearly seen in reduced 
visibility 50 or 100 miles away. A survey, possibly using 
aircraft, of the spreading, vertically and horizontally, and 
the change in concentration of the smoke at different dis- 
tances would be of much interest. The results would need 
to be correlated with the meteorological conditions. 
A. R. Menruam. Ventilation of towns. The concentration 
of smoke and gaseous pollution at street level is only partly 
determined by wind, being less closely correlated with wind 
speed than with other factors related to atmospheric tur- 
bulence. There is no orthodox method of measuring ven- 
tilation by turbulence; but it can be studied in towns where 
there is a large central park or smokeless zone by measuring 
the ratio of pollution in the center of the park to that a short 
way upwind. In Hyde Park, London, the ratio varied from 
0.27 in high turbulence to 0.85 in low turbulence [24, p. 71]. 
M. E. Smira. Progress in meteorological research associ- 
ated with atmospheric pollution requires the accumulation of 
certain data which are currently difficult to obtain with- 
out elaborate facilities. It is therefore desirable that rela- 
tively imexpensive equipment and simple techniques be de- 
veloped to obtain these data. A thorough investigation of 
the usefulness of radio-wave propagation for the measure- 
ment of vertical temperature and humidity structure is 
particularly promising, since the equipment presumably would 
not involve the use of fixed towers or masts. 
The determination of the extent to which wind tunnels 
can be used to simulate atmospheric turbulence by varia- 
tion of vertical density structure, as well as other param- 
eters, is also worthy of consideration. Such an investigation 
would establish more clearly the significance of numerous 
tests which have been made, and might provide an invaluable 
research tool for the investigation of proposed industrial 
installations. 
O. G. Surron. The situation in Great Britain at present is 
as follows. There is in existence a well-coordinated system of 
observations in the vicinity of sources of pollution, using 
standard instruments (deposit gauges, lead peroxide cylin- 
ders, etc.) which are provided by the Fuel Research Sta- 
tion of the Department of Scientific and Industrial Research 
and operated by the local authorities (town and borough 
councils). This procedure ensures that observations taken 
in different localities are comparable, a very important point 
for the subsequent statistical investigation. The results are 
analyzed by the Fuel Research Station and the final statis- 
tics, with maps of distribution, are issued in an official publica- 
tion. 
The main effort of the past decade, apart from research 
on instrumentation, has been the study of pollution at a 
selected site. The best known example is the Leicester Survey 
[24]. Although attempts were made in this survey to inves- 
tigate the underlying physics of the distribution of pollution, 
it is probably fair to describe this work as primarily con- 
cerned with establishing the facts (in a statistical sense) of 
the distribution of pollution around a center of industry. 
The nature of the raw data and the heterogeneous character 
1155 
of the source made any really detailed physical study impos- 
sible. 
It is hoped that it will now be possible to make more 
individual studies. The mathematical theory, although in- 
complete and by no means fully established, is now sufficiently 
advanced to give direction to the necessary experimental 
work. This should take the form of wind-tunnel investiga- 
tions, supplemented by full-scale observations, of the dis- 
tribution of pollution from a specific source, such as a power 
plant. This technique should be useful, for example, in 
revealing any tendency towards dangerous pockets of pollu- 
tion in heavily contoured areas, by employing relief maps of 
the district with chemical indicators. Secondly, it should 
prove possible to establish a technique of experimentation 
for the prior investigation of a proposed factory or power 
plant layout to ensure that the effluent has a reasonable 
chance of getting away without being caught in some local 
eddy system and thus brought down to ground level in a high 
concentration. 
To sum up, attention should now be directed more to- 
wards the mathematical-physical and experimental study of 
individual sources, and less towards the statistical survey 
of a polluted area. The routine observations should continue 
at all costs, since they form the essential factual basis of the 
problem. 
Fig. 2 is copyright by the American Chemical Society 
and reproduced by permission of the copyright owner. 
Fig. 4 is reproduced from Technical Paper No. 1, 
Atmospheric Pollution Research, Department of Scien- 
tific and Industrial Research, Great Britain, is Crown 
copyright, and is reproduced by permission of H. M. 
Stationery Office. 
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