1152 
increasingly acute; most rivers already receive more 
wastes than is desirable, and the dumping of wastes 
out-of-doors in large piles mars the landscape and 
raises other problems. However, these are not the only 
possibilities. For example, the problem of the disposal 
of economically worthless smokes and fine dusts col- 
lected at the source could be alleviated by turning off 
Cottrell precipitators or other precipitating equipment 
when atmospheric turbulence is high and thus allowing 
the atmosphere to disperse the contaminants in very 
low concentrations over a wide area. A possible exten- 
sion of this method is to collect the fine particles during 
periods of low turbulence and then reintroduce them 
into the flue gases during periods when the diffusing 
action of the atmosphere is very high. A successful 
development of this method would thus permit at- 
mospheric disposal of all but the large particles. 
For a substantial fraction of the time the atmos- 
phere is an excellent diffusing agency, spreading gases 
and aerosols over such wide areas in such low con- 
centrations that they present no problem. It seems 
only reasonable to use this natural diffusing agency in 
the disposal of industrial wastes whenever possible. 
Climatological Planning. Although the problem of 
waste disposal in the atmosphere is only one of a num- 
ber to be considered when selecting a site for a new 
plant, considerable alleviation of pollution could be 
achieved if more weight were given to this factor. It is 
obvious that, if at all possible, a new plant should be 
located so that the prevailing winds will carry con- 
taminants away from, not toward, populated areas, 
fertile agricultural land, valuable timber stands, etc. 
The prevalence of calm conditions, both persistent and 
transient, which lead to small lapse rates and inversions 
near the surface, taken in conjunction with local oro- 
graphic conditions, should also be considered [104]. 
Thus, in the Los Angeles area, the records show that, 
on the average, inversions occur 260 days a year, of 
which 65 days are characterized by marked inversions. 
The persistence of such inversions is important in 
assessing the probable pollution nuisance. If it is found 
desirable to locate industrial plants in areas where 
natural diffusing conditions are poor, a knowledge of 
that fact would permit the design of plant equipment 
for the effective mitigation of the potential nuisance. 
If a system of meteorological control is to be estab- 
lished, a study of the pertinent climatological data 
would provide information on the degree of curtailment 
of emission of contaminants desirable at various times 
of the year, the duration of periods of curtailment, and 
other facts of value in designing the requisite plant 
equipment. If substances are to be removed from the 
effluent and used in the manufacture of by-products, 
climatological data would permit an estimate of the 
required plant capacity and of its probable utilization 
throughout the year. 
Methods of using climatological data for the solution 
of certain problems have been developed. Down-wash 
of contaminants in large-scale eddies in the lee of 
buildings may be marked when winds are high. Sherlock 
[72] has described a method of using wind data to 
ATMOSPHERIC POLLUTION 
determine how frequently such down-wash is likely 
‘to occur over a period of years. Lowry [52] has developed 
a basis for a pollution climatology. The necessary data 
are obtained from an anemometer and a wind vane 
at the proposed level of the top of the stack. Maximum 
ground concentrations are obtained from equation (7); 
the wind vane gives the appropriate value of the 
quantity a,, and the anemometer gives the value of the 
mean wind speed w, both for the period of one hour. 
The quantity o in (8) is obtained from the wind vane. 
The two equations then give the mean maximum ground 
concentration for one hour and the distance from the 
source at which this mean maximum occurs. The longer 
the exploratory observations are contmued the more 
accurate and reliable will be the results. To facilitate 
the use of the method, mean values are given Of Om 
and o appropriate for the four types of gustiness shown 
by the wind vane and illustrated in Fig. 5. Allowance 
has been made for the high morning concentrations 
which often occur in summer, but the method is subject 
to the other limitations of current theories which have 
been described earlier. 
Climatological planning is especially urgent in con- 
nection with industrial mstallations in valleys, as dem- 
onstrated by the disasters in the Meuse River valley in 
Belgium and at Donora in the Monongahela River 
valley which have been described earlier. Climatological 
studies of the relevant meteorological parameters would 
reveal how often dangerous accumulations in the valley 
are likely to occur, at what seasons of the year, and 
their probable duration. Such studies would also pro- 
vide data for industrial plants in the valley to permit 
them to design units of the necessary capacity for 
collecting contaminants at the source. 
THE PRESENT POSITION AND 
FUTURE REQUIREMENTS 
A survey of atmospheric pollution studies indicates 
that advance in the meteorological aspects of the prob- 
lem has been most rapid in Great Britain and the 
United States. 
Systematic studies began earlier in Great Britain 
when, in 1912, a conference of delegates of municipal 
authorities and others was held in connection with the 
Smoke Abatement Exhibition in London. At that time 
a committee was appointed to “draw up details of a 
standard apparatus for the measurement of soot and 
dust and standard methods for its use.” The com- 
mittee’s first report covered operations during the period 
April, 1914, to March, 1915. Since that time systematic 
measurements of contaminants in a number of cities 
have been made. However, detailed studies of the 
relationship between city pollution and meteorological 
conditions were not made until 1937, when a three- 
year survey of the city of Leicester [24] was commenced. 
Important experimental and theoretical contributions 
to the solution of problems presented by point and 
line sources have been made independently by Sutton 
and the group which worked under him at the Chemical 
Defence Experimental Station, Porton. 
