TABLE 10.-Emissions estimates with percent vehicular contribution 1

REFERENCES

1. E. F. Darley, E. R. Stephens, J. T. Middleton, P. L. Haust (Intern. J. Air Water Pollution, 1, 155 (1959)).

2. N. A. Renzetti, E. A. Schuck (J. Air Pollution Control Assoc., 11, 121 (1961)).

3. E. A. Schuck, G. J. Doyle, "Photooxidation of Hydrocarbons in Mixtures Containing Oxides of Nitrogen and Sulfur Dioxide" (Dept. No. 29, Air Pollution Foundation, San Marino, Calif.).

4. E. R. Stephens, E. F. Darley, O. C. Taylor, W. E. Scott "Photochemical Reaction Products in Air Pollution" (Int. J. Air Water Pollution, 4, 79-100 (1961)).

5. J. T. Middleton, "Photochemical Air Pollution Damage to Plants" (Ann. Rev. Plant Physiology, 12, 431-488 (1961)).

6. J. T. Middleton, E. F. Darley, "Damage to Vegetation from Polluted Atmospheres" (J. Air Pollution Control Assoc., 8, 9-15 (1958)).

7. J. T. Middleton, A. J. Haagen-Smit, "The Occurrence, Distribution, and Significance of Photochemical Air Pollution in the United States, Canada, and Mexico" (J. Air Pollution Control Assoc., 11, 129-134 (1961)).

8. L. G. Wayne, "The Chemistry of Urban Atmospheres" (Technical progress Report, vol. III, Los Angeles Co. Air Pollution Control District (1962)).

9. E. F. Darley, W. M. Dugger, J. B. Mudd, L. Ordin, O. C. Taylor, E. R. Stephens, "Plant Damage by Pollution Devised from Automobiles" (Arch. Envir. Health, 6, 761-770 (1963)).

10. O. C. Taylor, "Oxidant Air Pollutants as Phytotoxicants," presented at 57th annual meeting of the Air Pollution Control Association, Houston, Tex., June 21-25, 1964.

11. B. L. Richards, J. T. Middleton, W. B. Hewitt, "Oxidant Stipple of Grapes" (Agron. J., 50, 559-561 (1958)).

12. M. C. Ledbetter, P. W. Zimmerman, A. E. Hitchcock, "The Histopathological Effects of Ozone on Plant Foliage" (Contrib. Boyce Thompson Inst., 20, 275-282 (1959)).

13. H. E. Heggestad, J. T. Middleton, "Ozone in High Concentrations as Cause of Tobacco Leaf Injury" (Science, 129, 208–210 (1959)).

14. A. C. Hill, M. R. Pack, M. Treshow, R. J. Downs, L. G. Transtrum, "Plant Injury Induced by Ozone" (Phytopath., 51, 356-363 (1961)).

15. H. A. Menser, H. E. Heggestad, O. E. Street, "Response of Plants to Air Pollutants, II, Effects of Ozone Concentration and Leaf Maturity on Injury to Nicotiana Tobacum" (Phytopath., 53, 1304-1308 (1963)).

16. B. L. Richards, O. C. Taylor, “Significance of Atmospheric Ozone as a Phytotoxicant," presented at the 57th annual meeting of the Air Pollution Control Association, Houston, Tex., June 21-25, 1964.

17. W. M. Dugger, Jr., O. C. Taylor, E. Cardiff, C. R. Thompson, "Stomatal Action in Plants as Related to Damage from Photochemical Oxidants" (Plant Physiol., 37, 487-491 (1962)).

18. O. C. Taylor, W. M. Dugger, Jr., E. A. Cardiff, E. F. Darley, "Interaction of Light and Atmospheric Photochemical Products (Smog) Within Plants" (Nature, 192, 814-–816 (1961)).

19. J. T. Middleton, "Air Conservation and the Protection of Our Natural Resources," technical report of California Standards for Ambient Air Quality and Motor Vehicle Exhaust, State of California, Department of Public Health, 2151 Berkeley Way, Berkeley, Calif.

20. Communication from Mr. Joseph Palomba, Colorado Department of Public Health, dated July 14, 1964.

21. Annual Report of the Metropolitan Washington Council of Governments Oxidant Sampling Network. October 1962-September 1963.

22. J. T. Middleton, "Air Conservation and Natural Resources," proceedings of the National Conference on Air Pollution, December 10–12, 1962.

23. Communication from Dr. Robert Daines, Rutgers University College of Agriculture Department of Plant Pathology, dated July 13, 1964.

24. F. W. Went, "Global Aspects of Air Pollution as Checked by Damage to Vegetation," National Air Pollution Symposium (April 1955).

25. C. R. Berry, L. A. Ripperton, "Ozone, a Possible Cause of White Pine Emergence Tipburn" (Phytopathology 53, No. 5, 552–557 (May 1963)).

26. Annual Report of the Metropolitan Washington Council of Government Oxidant Sampling Network. October 1962-September 1963.

27. A Report to the Legislature on Air Pollution in Colorado, Colorado State Department of Public Health, 4210 East 11th Avenue, Denver, Colo.

28. Future Highways and Urban Growth, Wilbur Smith & Associates, 1961. 29. Personal correspondence from H. E. Heggestad to Louis S. Jaffee, dated January 29, 1965.

30. D. Sechtler, D. R. Davis, "Ozone Toxicity in Small Grains," Plant Disease Reporter, 48, 12, 919 (Dec 15, 1964)

31. "Air Pollution in Georgia. A Cooperative Statewide Survey," April 1962, State of Georgia, Department of Public Health and Public Health Service.

32. S. Hochheiser, S. W. Horstman, G. M. Tate, Jr., "A Pilot Study of Air Pollution in Birmingham, Ala., Robert A. Taft Sanitary Engineering Center Technical Report A62-22, May 1962.

33. Denver Metropolitan Area Air Sampling Survey, September 1961, Colorado State Department of Public Health.

34. "Report of the International Joint Commission United States and Canada on the Pollution of the Atmosphere in the Detroit River Area, 1960," International Joint Commission.

35. J. P. Sheeby, J. J. Henderson, C. Y. Harding, A. L. Danis, "A Pilot Study of Air Pollution in Jacksonville, Fla., August-September 1961, December 1962." 36. J. E. Yocum, J. M. Saslaw, S. Chapman, R. L. Richardson, "Summary Report on Research Investigations of Air Pollution in the Vicinity of Louisville, Ky., Report to Rubbertown Industrial Group," Battelle Memorial Institute, Columbus, Ohio, July 1954.

37. "An Appraisal of Air Pollution in Minnesota, October 1959-July 1960, January 1961," Minnesota Department of Health.

38. J. D. Williams, N. G. Edmiston, "A Proposal for Air Resource Management in the Nashville Metropolitan Area," unpublished.

39. "Air Pollution in Phoenix, Ariz., Report No. 1 on Air Pollution, January 1958," Arizona State Department of Health.

40. M. D. High, R. W. Slater, G. G. Costantino, "A Pilot Study of Air Pollution in Providence, R.I.," Robert A. Taft Sanitary Engineering Center Technical Report A62-15, June 1962.

41. G. B. Welsh, "An Appraisal of Air Pollution in Spartanburg, S.C.," April 1962.

42. "Air Pollution in Tucson, Ariz., Report No. 2 on Air Pollution, January 1959," Arizona State Department of Health.

43. Q. M. Mees, R. L. Wortman, "Preliminary Report, Air Pollution Surveillance Study, Tucson, Ariz.," Bulletin No. 13, Civil Engineer Series No. 6, University of Arizona, Tucson, Ariz., August 1960.

44. Annual Report of the Metropolitan Washington Council of Governments Oxidant Sampling Network, October 1961-September 1962, October 1962. Regional Air Pollution Advisory Board of the Council of Governments.

45. "A Pilot Study of Air Pollution in Washington, D.C., December 2-8, 1960," Department of Public Health, District of Columbia and U.S. Public Health Service.

46. B. C. Newbury, "Pollution Levels in Rural Southern Ontario," paper presented at the annual meeting of the Air Pollution Control Association, Cincinnati.

[From Time, Feb. 19, 1965]

CHEMISTRY

MONOXIDE RIDES THE FREEWAYS

Dutch-born Biochemist Arie Jan Haagen-Smit of Caltech, a Los Angeles city consultant on air pollution, has been doing his research while riding the Los Angeles-Pasadena freeway. His ancient Plymouth rigged with a portable carbon monoxide detector, he has sampled the tainted atmosphere at all times of day. As far out as Pasadena, the detector shows fairly clean air, but as soon as Haagen-Smit hits the freeway the deadly monoxide begins to climb. Quickly it passes 30 parts per million, which California smog authorities consider serious pollution.

Stink at interchanges

Saturdays are not so bad; the cruising sniffer can drive all the way downtown without seeing the needle push above 40 parts per million. During weekday rush hours, though, it sometimes hits a peak of 120 parts per million. "It is most exciting," says Haagen-Smit. "You get behind another car, and the pointer

51-707-65- -9

goes way up, especially where you have a slowdown of traffic." Top readings come at the nightmarish interchanges, where curling roadways tangle like spaghetti on a fork and hundreds of car engines pant in frustration. "Tunnels and depressions concentrate the carbon monoxide," says the professor, “but in that interchange area it's really stinking."

Carbon monoxide is a cumulative poison that has a strong affinity for the hemoglobin in the blood, putting it out of action and reducing the blood's power to carry oxygen to the body's tissues. "If you breathe 30 parts per million for 8 hours," says Haagen-Smit, "5 percent of the oxygen capacity of your blood is taken away." Exposure to the highest concentrations found on the freeways knocks out the same amount of hemoglobin in 1 hour, and Haagen-Smit believes that 5 percent loss is too much, especially for car commuters with heart ailments, emphysema, or other respiratory troubles.

No filters work

Nothing much can be done at present about carbon monoxide except to stay out of heavy traffic. Greater Los Angeles has almost no transportation except private cars. "No filters work against carbon monoxide," says Haagen-Smit, "and closing the windows may be dangerous." He reports that in one tightly closed test car with a faulty exhaust, the interior carbon monoxide jumped to 200 parts per million He hopes a little improvement will come next fall from new cars equipped with devices to reduce carbon monoxide in their exhaust. Worst affected by exhaust fumes are the eager tailgaters who cause the manycar pile-ups for which the freeway are famous. "The way to get the biggest dose," says Haagen-Smit, "is to keep as close as one can to the car ahead of you. The fellow who does that gets the most carbon monoxide, also the most lead, oxides of nitrogen, carcinogens, everything."

Abstract.-Until a few years ago damage to forests from air pollution consisted mainly of localized but very severe cases of mortality and growth loss due to oxides of sulfur or to fluoride associated with ore reduction, with a minor contribution from other sources. In recent years oxidant damage, attributed largely to ozone in Los Angeles smog, is considered partly responsible for destroying ponderosa pine in the mountains east of that city. Oxidant has also been determined as the cause of a long-known needle blight of eastern white pine now called emergence tipburn, and evidence is accumulating that the eastern white pine disease long known as chlorotic dwarf may be due to an abiotic air-borne agent. Mortality and growth loss of this species has also been occuring within a 20-mile radius of certain powerplants consuming large quantities of soft coal. When potted ramets (vegetative reproductions) of selected sensitive white pine clones were exposed in an area embracing an industrial complex in east Tennessee, exposure for 7 months resulted in uniformly severe damage. Ramets from resistant trees, similarly exposed, suffered no damage. Sensitive ramets kept out of the affected area remained healthy. New and important types of crop damage, including damage to trees, appears to be resulting from air pollution asociated with our enormous urban development, with stack gases from new industrial processes, and with greatly increased emissions of stack gases from industrial plants using fossil fuels at rates far beyond consumption only 15 years ago.

The Clean Air Act (10), passed by the 88th Congress in December 1963, states "that the growth in the amount and complexity of air pollution brought about by urbanization, industrial development, and the increasing use of motor vehicles, has resulted in mounting dangers to the public health and welfare, including injury to agricultural crops and livestock, damage to and the deterioration of property, and hazards to air and ground transportation."

1 A paper presented at North Carolina State of the University of North Carolina at Raleigh, Apr. 9, 1964, as one of the university's institute of biological sciences lecture series.

2 The author is principal research scientist, Forest Disease Research, U.S. Forest Service, Asheville, N.C.

This recognition by Congress of the hazards imposed by the various forms of air pollution to our health and welfare indicate that they can no longer be ignored and no longer be considered local problems with which public agencies need not become involved. Until recent years most of our streams were treated as common sewers into which virtually any liquid waste could be dumped. This situation resulted in a multitude of health, wildlife, and other water use problems that have led to the widespread adoption of strong measures for stream pollution abatement. The public has been slower to recognize the dangers of polluting the atmosphere. So long as acute impacts remained isolated cases, dealt with locally, settled by agreement or litigation, or considered the result of meteorological acts of God, the air has been widely used in the "common sewer" sense with respect to gaseous emissions.

In recent years, however, there has been a slow but steady increase in public awareness of the chronic buildup of pollution levels in many parts of the world. This has been due in part from episodes like the Donora, Pa., fumigation of 1948, the London acute smog of 1952, the smog effects of the Los Angeles area, and from the clear evidence of chronic damage, not only to health but to property, to products of many kinds including paint and rubber, and to agriculture and forestry.

The current literature on the causes and effects of air pollution is enormous and new periodicals on the subject have been appearing at a rapid rate. Good summaries of our air pollution problems were presented by McCabe in 1952, who assembled the contributions to the deliberations of the U.S. Technical Conference on Air Pollution (24), by Stern, who edited an excellent compendium (35), by several authorities in the monograph "Air Pollution," released by the World Health Organization in 1961 (40), and by the proceedings of the two National Air Pollution Conferences (37, 38). The possible effects of ionizing radiations on plants are not included in the present review.

Information on the many types of air pollution damage to economic plants has been brought together recently by Thomas (36), Middleton (25), and others (1, 20). In the past the principal pollutants have been oxides of sulfur from industrial sources and from London-type smog, and fluorine mainly from ore reduction and the preparation of phosphate fertilizers. Today many additional constituents of polluted air are known to contribute to plant damage, particularly ozone and peroxidized compounds such as peroxyacetyl nitrate (PAN), which are the main elements of Los Angeles-type smog that are toxic to plants and animals. Ozone and PAN result from photochemical reactions between oxides of nitrogen and organic vapors mostly derived from the incomplete combustion of petroleum. In addition to the four principal pollutants already mentioned (sulfur dioxide, fluoride, ozone, and PAN), plant damage has been caused by sulfur dioxide at field levels; gladiolus, azalea, and vaccinium are among hydrogen sulfide, and others (36). While nitrogen oxides are essential to the formation of photochemical smog, and can themselves be toxic to plants (26), some consider it questionable that they occur in the atmosphere in concentrations high enough to cause injury directly (36).

Virtually all of the principal types of agricultural crops have suffered important damage from air pollution. A few examples among nonforest crops might be mentioned (36). Alfalfa, cotton, and lettuce have been readily injured by sulfur dioxide at field levels; gladiolus, azalea, and vaccinium are among the most sensitive plants to fluorine; ozone produces weather fleck in tobacco (13); ethylene ruins orchid blooms; and a recent report of the University of California states that the photo-chemical smog from Los Angeles has reduced the production of citrus fruit in the main California citrus area south of that city by 20 to 25 percent in the past 15 years (4).

PAST AIR POLLUTION IMPACTS TO THE FOREST

Scheffer and Hedgcock (32), in their bulletin on injury to northwestern forest trees by sulfur dioxide from smelters, give a brief literature review of air pollution damage to forests and state that sulfur dioxide discharged from smelters had been the major cause of gas injury to forest trees. The National Research Council of Canada in 1939 released a 447-page report (29) on the effects of sulfur dioxide on vegetation, and damage to coniferous trees from smelting was a major feature of this report. Katz (19), in Canada, further described damage to coniferous forests from sulfur dioxide, and later Linzon (21) measured and documented heavy damage to white pine from sulfur dioxide