296 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1956 



inversion. If the expected degree of contamination is determined 

 before dangerous concentrations are reached, then the operational ex- 

 penses of many methods of pollution abatement as well as the invest- 

 ment in special control equipment could be greatly reduced. Evacua- 

 tion into the atmosphere is indeed one of the best and most economical 

 methods of disposing of pollutants. If we are able to determine the 

 periods of time when such evacuation can be made without danger, 

 then during those periods the use of the special equipment or special 

 fuel will not be necessary. It is therefore important to determine the 

 unfavorable conditions much more correctly than a human forecaster 

 is able to do, since any action to reduce the emission of pollutants dur- 

 ing the unfavorable time will be expensive. The meteorologist would 

 alert the computing center whenever there seemed to be a possibility 

 of unfavorable meteorological conditions. The computing center 

 would then take over the problem of continuously following the mean 

 wind velocity pattern, the turbulence characteristics, and the tempera- 

 ture inversion in the area. From these data the concentration of pol- 

 lutants which may be reached over the area will be computed. At 

 some chosen points of the area the concentration in contaminants will 

 be measured and the results relayed to the computing center to im- 

 prove the precision of the computation. The high-speed computation 

 will determine what the expected concentration distributions will be 

 if the operation of the sources of pollution continues without change. 

 If, at any point in the protected area, the occurrence of a dangerous 

 concentration is predicted, action would have to be taken to reduce the 

 emission of pollutants. It will be possible to determine which indi- 

 vidual sources contribute most to the dangerous concentrations, since 

 the computation is done by adding the effects of the various sources. 

 One will then find what the effects of shutting-down or reducing the 

 production of pollutants at some of these individual sources will be on 

 the predicted concentrations. As a result it may be sufficient to take 

 such action at only some of the sources of pollution and limit the ex- 

 pense and inconvenience to a minimum. 



URBAN PLANNING 



A growing urban area must expect an increase of atmospheric pollu- 

 tion unless a greater effort in its abatement measures balances the 

 effects of additional sources of pollution. As an example, we shall 

 use again Los Angeles County (or rather the mathematical model 

 representing the County) and forecast the mean concentration at the 

 California Institute of Technology for 1960 and 1980. This forecast 

 will be based on data concerning the future increase in population, 

 fuel consumption, and so forth. To simplify this computation, we 

 shall use the same mathematical model of Los Angeles County as we 



