Pollution photochemical air

Today in many major urban areas around the world, air pollution is characterized more by the formation of ozone and other oxidants rather than by S02, particles, and sulfuric acid. In these regions, the primary pollutants are NOx (mainly NO) and volatile organic compounds (VOC), which undergo photochemical reactions in sunlight to form a host of secondary pollutants, the most prominent of which is Ov Some of these are 

TABLE 1.2 Historical Aspects of Sulfurous (London) and Photochemical (Los Angeles) Air Pollution 

Secondary pollutants H2S04, sulfate aerosols, etc. 03, PAN, HNO, aldehydes, particulate nitrate and sulfate, etc. 

Relative humidity High, usually foggy Low, usually hot and dry 

Type of inversion Radiation (ground) Subsidence (overhead) 

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G. J. McRae, Mathematical Modeling of Photochemical Air Pollution, Ph.D. dissertation, California Institute of Technology, Pasadena, Calif., 1981. 

Lamb, R. G., "A Regional Scale (1000 km) Model of Photochemical Air Pollution. Part... 

Photochemical air pollution (PAP) Polliit ants such as nitrogen oxide and certain hydrocarbons that cause photochetnical reactions in the air. 

One strategy in limiting the formation of ozone and other photochemical oxidants has been the use (in the past) of low reactivity fuels in internal combustion engines. More recently, alternate fuels (methanol, for instance) have been proposed for regions that suffer from elevated levels of photochemical air pollution. The effect of switching to such a low-reactivity fuel may be seen in Equation E2 for methanol, which has a simple atmospheric reaction mechanism. 

Certainly, photochemical air pollution is not merely a local problem. Indeed, spread of anthropogenic smog plumes away from urban centers results in regional scale oxidant problems, such as found in the NE United States and many southern States. Ozone production has also been connected with biomass burning in the tropics (79,80,81). Transport of large-scale tropospheric ozone plumes over large distances has been documented from satellite measurements of total atmospheric ozone (82,83,84), originally taken to study stratospheric ozone depletion. 

Arey, J., Atkinson, R., Zielinska, B., McElroy, P.A. (1989) Diurnal concentrations of volatile polycyclic aromatic hydrocarbons and nitroarenes during a photochemical air pollution episode in Glendora, California. Environ. Sci. Technol. 23, 321-327. 

MODELING LOS ANGELES PHOTOCHEMICAL AIR POLLUTION. (1975) (Sponsor Dreyfus Foundation)... 

Photochemical air pollution consists of a complex mixture of gaseous pollutants and aerosols, some of which are photochemically produced. Among the gaseous compounds are the oxidizing species ozone, nitrogen dioxide, and peroxyacyl nitrate ... 

McAfee, J. M., J. N. Pitts. Jr., and A. M. Winer. In-situ Long-path Infrared Spectroscopy of Photochemical Air Pollutants in an Environmental Chamber. Paper No. 125 Presented at the Pacific Conference on Chemistry and Spectroscopy, San Francisco, California, October 16-18, 1974. (American Chemical Society—lOth Western Regional Meeting and Society for Applied Spectroscopy—13th Pacific Meeting)... 

Dickson, D. R., and N. Quickert. The chemical composition of photochemical air pollution, pp. 27-51. In NRC Associate Committee on Scientific Criteria for Environmental Quality. Report No. 12. Photochemical Air Pollution Formation, Transport and Effects. Ottawa National Research Council of Canada, 1975. 

Schuck, E. A., and R. A. Papetti. Examination of the photochemical air pollution problem in the southern California area. Appendix D. In Technical Support Document for the Metropolitan Los Angeles Intrastate Air Quality Control Region Transportation Control Plan Final Promulgation. San Francisco U.S. Environmental Protection Agency, Region IX, Oct. 30, 1973. 19 pp. 

Among the many effects of histamine are edematogenic alterations in vascular endothelium and bronchoconstriction. The latter may be particularly pertinent, in view of its being a central manifestation of asthma attacks and of the reported association of asthma attacks with photochemical air pollution. Bronchoconstriction has also been observed in animals and man experimentally exposed to ozone or photochemical air pollution. 

Jaffe, L. S. Photochemical air pollutants and their effects on men and animals. II. Adverse effects. Arch. Environ. Health 16 241-255, 1968. 

A second study by the epa will attempt to correlate the effects of photochemical oxidants and cigarette-smoking in promoting chronic respiratory signs and symptoms in cohorts of adolescents and their families. Pulmonary-function tests will be included, and this study should do much to answer the vexing questions of the relationship of chronic pulmonary disease and photochemical air pollution. 

Kagawa, J., and T. Toyama. Photochemical air pollution. Its effects on respiratory function of elementary school children. Arch. Environ. Health 30 117-122, 1975. 

Injury to vegetation was one of the earliest indicators of photochemical air pollution. Injury was first observed in the Los Angeles area in 1944. Since then, there has been a slow but steady increase in research efforts to understand the effects of these pollutants on vegetation. In the late 1960 s and early 1970 s, there has been a flood of published information. 

Costonis, A. C., and S. N. Unzon. Methods for measuring photochemical air pollution in forest areas. Mitt. Forst. Bundes-Versuch. 92 57-70, 1971. 

Heck, W. W., and A. S. Heagle. Measurement of photochemical air pollution with a sensitive monitoring plant. J. Air Pollut. Control Assoc. 20 97-99, 1970. 

Heggestad, H. E. Photochemical air pollution injury to potatoes in the Atlantic coastal states. Amer. Potato J. 50 315-328, 1973. 

Thompson, C. R., E. Hensel, and G. Kats. Effects of photochemical air pollutants on Zinfandel grapes. HortScience 4 222-224, 1969. 

Kkkert. R. N.. P. R. MUler. O. C. Taylor, J. R. McBride. J. Barbieri, R. Arkley. F. Cobb, Jr., D. Dahlsten, W. W. WUcox. J. Wenz, J. R. Panneter, Jr., R. F. Luck, and M. White. Photochemical Air Pollutant Effects on Mixed Conifer Forest Ecosystems. A Progress Report. CERL-026. Contract No. 684)3-0273. Corvallis. Oregon Corvallis Environmental Research Laboratory, U.S. Environmental Protection Agency, [1976]. 275 pp. 

Light. Photoperiod has a marked effect on susceptibility of plants to photochemical air pollutants. The effect of photoperiod is particularly striking when peroxyacetyl nitrate (PAN) is the principal toxicant, but there is also a significant effect... 

Table 1.2 summarizes some aspects of London and photochemical air pollution that have traditionally been considered to differentiate the two. However, as we shall see, it has become clear since the mid-1970 s that these two, along with such phenomena as the fate of airborne toxic chemicals, are inextricably linked through their atmospheric chemistry. It is this common linkage that forms the central core of this book. 

Certain reproducible features of time-concentration profiles for pollutants are observed in smoggy ambient air. Figure 1.3, a classic example of historical interest, shows such profiles for NO, N02, and total oxidant (mainly 03) in Pasadena, California, during a severe photochemical air pollution episode in July 1973. Reproducible features include the following ... 

In the early 1950 s, soon after the new phenomenon of photochemical air pollution had been reported, the fundamental chemistry responsible for many of these general features began to be established. Thus, as first suggested by F. E. Blacet in 1952, photodissociation of N02 in air was shown to form 03 (Blacet, 1952) ... 

This is a major chain propagation step in the overall reaction mechanism for ozone formation in photochemical air pollution. Because H02 is intimately tied to OH through reaction (17) and cycles such as that in Fig. 1.4, when NO is present the sources and sinks of H02 are, in effect, sources or sinks of the OH radical. 

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