Figure 6. Vehicle miles of travel in United States,

TABLE 7.-Summary of atmospheric concentrations of nitric oxide, nitrogen dioxide, and carbon monoxide from continuous air monitoring program, January-December 1964

TABLE 8.-Nitrogen dioxide concentrations measured by the national air sampling

TABLE 9.-Average carbon monoxide concentration-Continuous air monitoring

TABLE 10.-Emissions estimates with percent vehicular contribution 1

REFERENCES

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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)).

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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.

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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)).

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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)).

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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)).

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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.