ATMOSPHERIC POLLUTION — FRENKIEL 



0.048r 



0.044 - 

 0.040 _ 



0.036 - 



297 



0.032 - 



0.028 



0.024 



0.020 



0.016 



0.012 



0.008 



0.004 



2 4 6 8 10 12 14 I6__J8 20 22 24 

 HOUR OF DAY 



Figure 18. — Estimates of hourly variation of mean concentration at the California Institute 

 of Technology for 1960 and 1980, for the "important" pollutants, compared with the 1954 

 values taken from figure 12. (Based on estimates of population and industrial growth 

 and assuming no major change in their geographic distribution in Los Angeles County 

 and no improvement in the pollution control methods.) 



have used before. The result illustrated in figure 18 is determined for 

 the mean concentration of the most "important" pollutants. In this 

 figure, the curve for 1954 is the same as the one already shown on fig- 

 ure 11 ; the results for 1960 and 1980 assume that the abatement meth- 

 ods have the same efficiency as those for 1954. If we assume that the 

 allowable threshold concentration is, say 0.020, then the mean concen- 

 tration for 1960 will be larger than this allowable threshold value 

 between 8 a. m. and 8 p. m., and in 1980 from 7 a. m. to 3 a. m. of the 

 next day, as against the period of 10 a. m. to 3 p. m. for 1954. In 

 our mathematical model, these results correspond to the same meteoro- 

 logical conditions for each of the three cases. Obviously, the probable 

 number of days when the meteorological conditions will be favorable 

 for high concentrations of pollution in 1960 and 1980 will be larger 



