ATMOSPHERIC POLLUTION — FRENKIEL 



285 



of pollutants, would be reduced and the over-all time of operation of 

 motorcars would be shortened. The industrial pollutants may be 

 reduced, for the emergency period, by changing the hours of operation 

 of some of the industrial sources of pollution. The emergency meas- 

 ures could, for instance, attempt to distribute the pollution concen- 

 tration more uniformly over the 24-hour period to keep it below a 

 chosen value for the allowable threshold concentration at any hour. 

 0.024 



0.020 



0.016 



0.012 



0.008 



0.004 



HEATING 



10 12 14 

 HOUR OF DAY 



Figure 12. — Similar to preceding figure except that the incinerators are assumed to operate 

 between 4 p. m. and 8 p. m. instead of between 6 a. m. and 10 a. m. 



They must of course be applied in time to be effective ; this requires 

 a quantitative prediction of the mean concentrations to be expected 

 under various meteorological conditions. 



The emergency measures modifying the operation of the various 

 pollution sources may not always be sufficient, and the stoppage of 

 some of these sources may have to be considered. The effects of the 

 modification in the operation or of the complete stoppage of the 

 sources of pollution can be analyzed not only as far as the four 

 general sources of pollution (motorcars, oil and gas heating, incin- 

 erators, and industry) are concerned, but also with reference to in- 



