Atmospheric Pollution in Growing 

 Communities 1 



By Francois N. Frenkiel 



Applied Physics Laboratory, The Johns Hopkins University 



An urban community consists of an agglomeration of houses, com- 

 mercial and industrial buildings, paries, churches, and various loca- 

 tions in which human activities are performed. Most of these activi- 

 ties require the use of such air-polluting sources as motor vehicles, 

 railroads, house heating, refuse disposals, factories, and powerplants, 

 Like a living being, a living community breathes the surrounding air 

 and discharges the polluted air into the atmosphere. The very life 

 of an urban area must, therefore, be accompanied by atmospheric 

 pollution. In some cases, unfavorable meteorological conditions pro- 

 voke an accumulation of pollutants; in others the density of polluting 

 sources or their ineffective control are responsible for increasing con- 

 taminations. "VYhen, however, the meteorological conditions become 

 unfavorable, in an area with a particularly high density of polluting 

 sources, the air contamination may become very serious. 



In an urban area the pollutants emitted into the atmosphere by 

 such sources as industry, municipal and household incinerators, house 

 heating, motor vehicles, railroads, and the inhabitants themselves in- 

 clude solid particles, liquid droplets, vapors, and gases. Some of the 

 heavier particles fall out rapidly to the ground near the pollution 

 sources, and the lighter ones deposit at some distance. However, a 

 large amount of the pollutants move through the community before 

 they are dispersed into the surrounding areas. Sometimes a tempera- 

 ture inversion confines the pollutants to lower levels of the atmos- 

 phere, or a mountain chain restricts their dispersion out of the com- 



1 This article is based on a paper presented at the annual meeting of the Air 

 Pollution Control Association in Detroit, Michigan, May 22-26, 1955, and pub- 

 lished in the Scientific Monthly, April 1956, pp. 191-203. It is used by permission 

 of the editor of that journal. The present paper includes changes and additions 

 made during the author's part-time association with the David Taylor Model 

 Basin. A large part of the studies described were supported by the Bureau 

 of Ordnance, Department of the Navy, under contract NOrd 7386. 



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