Carbon monoxide urban pollutant

Human-made sources cover a wide spectrum of chemical and physical activities and are the major contributors to urban air pollution. Air pollutants in the United States pour out from over 10 million vehicles, the refuse of over 250 million people, the generation of billions of kilowatts of electricity, and the production of innumerable products demanded by eveiyday living. Hundreds of millions of tons of air pollutants are generated annu ly in the United States alone. The five main classes of pollutants are particulates, sulfur dioxide, nitrogen oxides, volatile organic compounds, and carbon monoxide. Total emissions in the United States are summarized by source categoiy for the year 1993 in Table 25-10. 

Although the original Clean Air Act of 1977 brought about significant improvements in air quality, the urban air pollution problems of ozone (known as smog), carbon monoxide (CO), and particulate matter (PM,o) persist. Currently, over 100 million Americans live in cities which are out of attaimnent with the public health standards for ozone. The most widespread and persistent urban... 

Air pollution is principally a problem in urban and heavily industrialized areas, where the flow of clean air from surrounding areas is insufficient to disperse the accumulation. Motor vehicles account for more than 50% of the man-made emissions of carbon monoxide, hydrocarbons, and nitrogen oxides (4). More than half of the U.S. annual trillion vehicle miles are driven in urban areas (5). Nature produces much more pollutants than all man-made sources, but natural emissions are widely dispersed and do not contribute heavily to urban pollution problems (6, 7). 

Carbon monoxide (CO) Is one of the most widely distributed air pollutants. It Is formed by natural biological and oxidation processes, the Incomplete combustion of carbon-containing fuels and various Industrial processes. However, the largest Individual source of man-made emissions Is motor vehicle exhausts which account for virtually all CO emitted In some urban environments. It has been estimated that global man-made emissions range from 300-1600 million tons per year, which Is approximately 60% of the total global CO emissions (22-23). 

The photochemistry of the polluted atmosphere is exceedingly complex. Even if one considers only a single hydrocarbon pollutant, with typical concentrations of nitrogen oxides, carbon monoxide, water vapor, and other trace components of air, several hundred chemical reactions are involved in a realistic assessment of the chemical evolution of such a system. The actual urban atmosphere contains not just one but hundreds of different hydrocarbons, each with its own reactivity and oxidation products. 

The classes of major primary pollutants that are important in urban areas are listed in Table 2-1. The pollutants most responsible for oxidant formation in the air are the nitrogen oxides, hydrocarbons, aldehydes, and carbon monoxide. The internal-combustion engine is a major source of emission of these primary pollutants, although many stationary sources. 

The air emissions of fossil fuel combustion are dispersed and diluted within the atmosphere, eventually falling or migrating to the surface of the Earth or ocean at various rates. Until recently, most attention was focused on the so-called primary pollutants of fossil fuel combustion that are harmful to human health oxides of sulphur and nitrogen, carbon monoxide, suspended particles (including soot), heavy metals, and products of incomplete combustion. These pollutants are most concentrated in urban or industrialized areas close to large or multiple sources. However, the primary pollutants may interact with each other, and with atmospheric constituents and sunlight, forming secondary pollutants that disperse far beyond the urban-... 

Dubois, L., Zdrojewski, A., Monkman, J. L. Analysis for carbon monoxide in urban air at the ppm-level, and the normal carbon monoxide level. J. Air Pollution Control Assoc. 16, 135 (1966). - Gas Chromatog. Abstr. 1969, 90. 

As discussed in Chapter 7, polluted air varies in composition from locale to locale and with the time of day and meteorological conditions in a given locale. Polluted urban air contains oxides of sulfur and nitrogen, carbon monoxide, ozone, uncombusted and partially combusted hydrocarbons from gasoline and diesel vehicles, and particulate matter. PM 2.5 particulates, the standard for evaluating pollution related to cardiovascular disease, are composed of combustion products, airborne soil, sulfates, nitrates, and heavy metals as listed in Table 29.4.141-45 ... 

Prior to 1995, around 85 million people (one-third U.S. population) lived in urban areas. The air quality of these areas violated federal public health standards, largely because of automotive pollutants. Gasoline and diesel-fueled cars, trucks, and buses produced half of all air pollution in the United States. This air pollution includes 66% of airborne carbon monoxide, 31%i of smog-forming hydrocarbons, and 43%i of lungdamaging nitrogen oxide. 

At local and urban levels, it is essentially a question of vicinity pollution. Several air pollutants are concerned sulphur dioxide, SO2 (primary pollutant) nitrogen oxides NO (primary or secondary pollutants) particulate matter PM (primary and secondary pollutants) carbon monoxide, CO, (primary pollutant) (volatile) organic compounds, HC (or VOCs) (primary and secondary pollutants), and photochemical oxidants, O3, PAN (secondary pollutants). Organic compounds account for a wide range of hydrocarbons and are found in solid, liquid, and gas forms. 

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