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MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE 



know if plants a,re as effective at night as during 

 the day in this removal. Would certain chemical 

 sprays aid removal of air toxicants by plants with- 

 out resulting injury to the plants? Developing 

 such information would be especially important 

 for growers near urban areas and for metropolitan 

 planners. 



Research on the air-cleansing capacity of foliage 

 is just beginning and needs to be expedited. 



Development of Protective Chemical Treatments 



Antioxidants and antiozonants protect plants 

 from ozone injury. Lime dusts reduce fluoride 

 injury. 



On cigar-wrapper tobacco, zineb is used com- 

 mercially for the control of a pathogenic disease, 

 but it also reduces the amount of ozone fleck. More 

 effective chemicals than zineb are available, but 

 the problem of residues remains to be solved. 



Little information is available about the use of 

 chemical protectants against other airborne toxi- 

 cants. But current information indicates that the 

 development of chemical protectants is a promis- 

 ing area of research. 



Rapidly growing plants are generally the most 

 sensitive to air pollutants. Seedlings sometimes 

 appear to be more sensitive than older plants. 

 Plants supplied with adequate soil moisture are 

 much more sensitive than those subjected to soil 

 moisture stress. 



The interrelated effects of nitrogen metabolism, 

 carbohydrate metabolism, and organic acid me- 

 tabolism in plants on their resistance to toxicity 

 appear to be very complex. Certainly these effects 

 are now poorly understood. Research information 

 is needed on these indicators of plant nutrition to 

 develop guides for better mineral fertilization 

 practices under conditions of chemical air 

 pollution. 



Development of Information and Procedures To 

 Lessen the Hazard and Intensity of Forest 

 Fires 



Forest fires contaminate the air by producing 

 tremendous quantities of smoke and hydrocarbons. 

 For example, every commercial airport in the 

 State of West Virginia was closed for nearly a 

 week in 1964 because of smoke from forest fires. 



Research into forest fire control is constantly 

 producing improved procedures that reduce the 

 total acreage burned and, consequently, the smoke 



and hydrocarbons produced. Such research has had 

 high benefits in relation to its costs. It is certainly 

 in the national interest to take every step possible 

 to reduce the hazard of forest fires and their tre- 

 mendous effluent of smoke and hydrocarbons. 



Develop Improved Procedures To Diminish Forest 

 Fires Caused by Electrical Storms 



Lightning causes more than 7,500 forest fires 

 during the average year. Such fires arc excep- 

 tionally expensive to control because, unlike man- 

 caused fires, they often occur in inaccessible coun- 

 try. In the Rocky Mountain States, lightning 

 sparks more than 70 percent of all forest fires. 

 Smoke from these fires has severely curtailed air 

 operations as far east as New York and Boston. 



Cloud-seeding techniques offer a strong potential 

 for reducing or eliminating lightning-caused fires. 

 In recent field trials, heavy overseeding with silver 

 iodide gave a one-third reduction in cloud-to- 

 ground lightning. The urgency in preventing 

 forest fires, not only to avoid contributions to air 

 pollution, but also to protect watersheds and con- 

 serve timber stands, indicates that appropriate re- 

 search move forward as rapidly as possible. 



Airborne Dusts 



Airborne dusts can be irritating, exasperating, 

 and frustrating. They arise from cement plants 

 and lime kilns, cotton gins, and alfalfa mills, 

 natural sand dune areas, unprotected fields and 

 rangelands, highway construction, and suburban 

 and industrial development. Dust clouds emanat- 

 ing from soil blowing on the Great Plains com- 

 prise big, dramatic, and usually disastrous events. 



Soil Blowing 



Masses of soil particles transported by the 

 winds have been known to cause physiological 

 damage to humans and livestock, depletion of the 

 soil resource, abrasion damage to growing crops, 

 increased home and office cleaning, reduced visi- 

 bility resulting in increased automobile accidents, 

 and many other costly effects. Recent findings 

 have revealed the presence of hydrocarbons from 

 chemical pesticides absorbed on air-transported 

 soil particles. 



Reduction of airborne soil particles depends 

 upon control of soil blowing. Although past re- 

 search has provided information toward under- 

 standing the processes, for the development of 



