AIRBORNE CHEMICALS 



Figure X-4 — A SYSTEM FOR DISCUSSING AIR POLLUTION 



The diagram shows a systems idealization of the problem of air pollution. Each 

 box represents a set of problems about which we may know something, but certainly 

 not enough to solve the problems or to understand exactly how that box may 

 interact with other boxes. It is interesting to note the role of social and political 

 considerations in the over-all air-pollution problem. They dominate our strategy 

 and tactics for the control of air pollution. 



the means for their control is quite 

 good, particularly with regard to the 

 contaminants that are emitted to the 

 atmosphere in greatest annual ton- 

 nage — namely, carbon dioxide, car- 

 bon monoxide, SOx, NO,, hydrocar- 

 bons, and particulate matter. (In 

 air-pollution parlance SCX and NO s 

 mean a mixture of oxides.) Present 

 knowledge of emissions that occur in 

 lesser annual tonnage is less precise; 

 and our control technology is fraught 

 with economic problems. 



Some of our apparent control tech- 

 nology has yet to be reduced to 

 commercial practice because of the 

 following dilemma: 



1. Application of the untried tech- 

 nology would represent a cost 



to the user that could be re- 

 covered only by raising the cost 

 of the product or service pro- 

 duced. 



2. Raising the cost of the product 

 or service would adversely af- 

 fect the competitive positions of 

 the applier of the technology 

 and will therefore be resisted 

 unless required by law or sub- 

 sidized by government. 



3. There is a reluctance to require 

 by law the application of an 

 untried technology. 



This leaves governmental subsidy as 

 the means to introduce untried tech- 

 nology. As yet, we have made only 

 halting steps in this direction. 



Once pollutants have been emitted, 

 we are concerned with their fate in 

 the atmosphere and the adverse ef- 

 fects they produce. Their life history 

 in the atmosphere starts with their 

 transport and diffusion from their 

 points of emission to their ultimate 

 receptors, during the course of which 

 they are subject to chemical reaction 

 in the atmosphere and a host of scav- 

 enging processes that tend to remove 

 them from the atmosphere. The result 

 of these several processes is measur- 

 able at any receptor point in terms of 

 the concentrations of the kinds and 

 forms of contaminants that survive to 

 reach the receptor. 



What we measure at a receptor 

 point we call "air quality." Because 

 of seasonal, diurnal, and microscale 



333 



