1154 
attention and a number of lines of attack along which valu- 
able progress may be anticipated. 
The following are our recommendations for future action: 
RECOMMENDATIONS 
1. That standardization in methods of handling several 
aspects of the problem be achieved at the earliest possible 
moment. In particular, standard instruments and procedures 
of evaluation should be evolved and adopted for use. Such 
standardized instruments, e.g., for direct measurements of 
turbulence, are required both for routine and research in- 
vestigations. If it is necessary to use non-standard imstru- 
ments, a full description of the operating characteristics of 
the equipment should be given. There is also an urgent need 
to adopt a standard terminology to ensure precision im pre- 
senting and conveying information. 
2. That the theoretical development of the subject be 
promoted in every way possible. The development of basic 
turbulence theory is a prerequisite for fundamental advance 
in the study of atmospheric diffusion, and must be fostered. 
3. That the problem of diffusion of effluents in a city be 
investigated intensively, since the pollution nuisance reaches 
the ultimate there. A program in which experiment and 
theory are both fully developed toward a common end is re- 
quired. For example, it is suggested that intensive surveys 
of pollution and the associated meteorological conditions be 
made by a team which would survey ten cities well distributed 
over the country in annual succession, the team spending a 
year in each city. Each city would be chosen as characteristic 
for certain features of terrain and climate. At the end of the 
ten-year period ten cities would have been studied in sufficient 
detail to permit a classification of diffusion conditions in each 
in terms of specific quantities. It may then be possible to 
extrapolate the detailed conclusions to other cities with the 
aid of only routine measurements in the latter for comparison. 
4. That micrometeorological and microclimatological sur- 
veys of cities and their suburbs be undertaken by local au- 
thorities with the assistance of a professional meteorologist. 
Instruments of standard type should be mounted on existing 
radio masts at standard heights with measured values pre- 
sented for standard times in standard units. A detailed out- 
line of the suggested procedure to be followed by local au- 
thorities in establishing such a survey should be prepared and 
distributed. Such a local survey would be relatively inexpen- 
sive. 
5. That whenever a meteorological survey is in progress, 
a continuous record of the magnitude and location of pollu- 
tion should be provided to permit correlation with meteoro- 
logical variables. This will require the establishment of a 
standard pollution index so that different cities can be com- 
pared. 
6. That the United States Weather Bureau be encouraged 
to take more observations of micrometeorological significance 
at its stations. Emphasis should be placed on obtaining regu- 
lar observations of gradients of temperature and wind in the 
lowest 500 feet of the atmosphere. 
7. That the organization be undertaken of existing and 
current literature on all phases of atmospheric pollution so 
that everyone may be aware of the work of those in other 
phases. Publication might be in toto or in abstract form. 
CONCERNING SPECIFIC PROBLEMS 
TO BE ATTACKED 
8. That, if possible, the relationship between wind-tunnel 
flow and natural atmospheric flow be established. 
9. That the means by which contaminants are removed 
from the atmosphere be studied in detail. Is the natural 
ATMOSPHERIC POLLUTION 
cleansing process rapid enough to warrant increasing the rate 
of disposal of wastes in the atmosphere? At times the at- 
mosphere is an extremely efficient disperser of gases and 
aerosols. In the long run, it may prove to be preferable to use 
this natural diffusing agency rather than removing contami- 
nants at the source; with atmospheric dispersal the problem 
of disposal of economically worthless substances does not 
arise. 
10. That an aerial survey of the distribution of inversion 
fog be undertaken. Atmospheric pollution tends to accumulate 
over terrain where such radiation fogs are of frequent oc- 
currence. 
11. That atmospheric electricity be measured more widely. 
The conductivity of the air depends on the degree of pollu- 
tion, and affords a convenient method of studying the secular 
trends of the latter [95, 100]. 
With serious attention given to the above and related prob- 
lems, meteorology will continue to make an increasing con- 
tribution to the solution of the problem of atmospheric pollu- 
tion. 
PROMISING LINES OF FURTHER RESEARCH 
In portions of some of the preceding sections the 
writer has outlmed his ideas on promising lines of 
attack on various aspects of the problem of atmospheric 
pollution. He is greatly indebted to a group of special- 
ists in the field who have, at his request, stated briefly 
their ideas on how we may best advance our knowledge 
of atmospheric pollution. These suggestions will be 
most valuable as guideposts to give direction to future 
research. The statements are given below. 
N. R. Bzsrs. It is important that one be able to determine 
the significant turbulence by using the ordinary weather map 
and simple and inexpensive observations at his own station. 
The principles involved in sound refraction may be applied 
to investigate inversion conditions with both source and re- 
ceiver on the ground. 
Fixed base observations along a horizontal line, as between 
the meteorological towers at Brookhaven, may be made to 
investigate the structure of eddies. I have suggested specifi- 
cally the possibility of hanging some 100 to 200 small bal- 
loons between the towers, to be fastened to the 900-foot-long 
“horizontal” cables. Motion pictures will illustrate the air 
movement between the towers at desired heights up to 100 
feet above ground. 
A general investigation should be made respecting trajec- 
tories of the air over a station, and nuclei of various kinds, 
such as sea salt, radon, pollen, dust, etc. The investigation 
must be carried out at several stations and at several eleva- 
tions above ground. 
Pui E. Cuurca. I believe that man has the right to 
breathe pure, clean, unpolluted air as well as to drink un- 
polluted water. It is not likely, however, that the time will 
soon come when no man-made pollutants of any type will be 
discharged into the atmosphere or when atmospheric pollu- 
tant sewage systems will be constructed. Until such time, 
the concentration of contamination reaching the level where 
man lives is largely at the mercy of the characteristics of the 
air into which the contaminant is ejected. Hence, we must 
know more about these atmospheric characteristics, par- 
ticularly in and near large and growing industrial centers. 
Especially important characteristics which must be thor- 
oughly known at all levels into which contaminants are or 
will be ejected are duration, frequency, and magnitude of 
stable and unstable lapse rates, and wind direction, gustiness, 
