ATMOSPHERIC POLLUTION — FRENKIEL 295 



teorological conditions for various periods of the year, using data 

 for several years. One must keep in mind, however, that there will 

 always be a certain probability of exceptional meteorological condi- 

 tions that would produce an abnormally high contamination. The 

 probability of such an occurrence can be reduced to any desirable 

 degree by appropriate zoning regulations. It should be noted that 

 it is not necessarily advisable to base the building restrictions on the 

 most unfavorable meteorological conditions. Temporary emergency 

 measures when such conditions prevail could be employed and in con- 

 sequence the restrictions could be relaxed. 



OPERATIONAL USE OF HIGH-SPEED COMPUTING 



The examples of mathematical models of atmospheric pollution 

 used in this paper were made sufficiently simple to avoid too ex- 

 tensive numerical computations. A more complete and more correct 

 analysis may require the use of high-speed electronic computing 

 machines. Some use of high-speed computing techniques was made, 

 in cooperation with the National Bureau of Standards [13], to evalu- 

 ate the applications of these techniques to atmospheric pollution 

 studies. It appears that high-speed computing techniques can be used 

 profitably, not only to obtain very rapidly results similar to those 

 described before, but also to forecast probable pollution patterns 

 fast enough to be able to take appropriate precautions when danger- 

 ous contamination levels are expected. 



The results discussed in the preceding sections were based on aver- 

 age meteorological conditions corresponding to a selected month of 

 the year, and their variations as a function of the hour of the day. 

 On each day of the month the meteorological conditions depart from 

 this average. One can, of course, use as a basis for the analysis the 

 meteorological conditions for each particular day and as a result 

 determine much more correctly the concentration patterns. Since 

 the use of mathematical models of atmospheric pollution requires ex- 

 tensive numerical computations, such an analysis will be practical 

 only if high-speed computing techniques are used. A method of 

 civil defense against radioactive pollution involving the use of high- 

 speed computers was suggested some years ago [14]. Similar meth- 

 ods show promise of success in problems of peacetime air pollution 

 of urban areas and can be used not only to analyze data on atmos- 

 pheric pollution and urban planning but also on an operational basis 

 in the control of atmospheric pollution. 



In an area to be protected from pollutants we place a net of instru- 

 ments measuring the directions and the magnitudes of the mean wind 

 velocities, the character of the turbulence, and other meteorological in- 

 formation such as, for instance, the characteristics of the temperature 



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