Motor vehicles exhaust emissions

EEC Directive on motor vehicle exhaust emission tests... 

Noble, W. M. The Relation of Plant Damage to Fuel Composition. Paper Presented at the Joint Research Conference on Motor Vehicle Exhaust Emissions and Their Effects, Dec. 5, 1%1, University of California, Los Angeles. 11 pp. 

Owing to their greater exposure to motor vehicle exhaust emissions, it is possible that fatty foods on sale at shops attached to petrol stations or at stalls and shops in busy roads could contain higher concentrations of aromatic hydrocarbons than similar foods on sale at other shops. A study in Germany found that concentrations of benzene and toluene were higher in retail packs from petrol stations on busy roads than from petrol stations in rural areas.15 It also found that retail packs from shops in busy roads contained higher concentrations of benzene, toluene, xylenes and ethylbenzene than retail packs from shops in residential areas. 

Gordon Larson who succeeded McCabe continued to reduce the emissions of refineries and other industries. He also undertook the control of emissions from open dump burning and backyard incinerators and made the initial contacts with the automobile industry to control motor vehicle exhaust emissions. However, in this drive to control the proved main sources of air pollution, Larson was opposed by the petroleum, chemical, and other industries, and primarily the individual citizen with his backyard incinerator. 

CATALYTIC CONTROL OF MOTOR VEHICLE EXHAUST EMISSIONS... 

Catalytic Converter an air pollution abatement device that removes pollutants from motor vehicle exhaust either by oxidizing them into carbon dioxide and water or reducing them to nitrogen. A typical catalytic oxidizer for auto emission control is illustrated in the sidebar figure. 

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). 

In Sweden, three-way catalysts have been required on all cars since 1989, and tax incentives were offered to purchase such vehicles in the 1987 and 1988 model years. Figure 16.34 shows the CO and hydrocarbon exhaust emissions as a function of model year of gasoline-powered cars, measured using a remote-sensing technique (Sjodin, 1994). There is a large decrease in the emissions from 1987 to 1988 and 1989, supporting the effectiveness of these motor vehicle exhaust controls. 

Toluene is released into the atmosphere principally from the volatilization of petroleum fuels and toluene-based solvents and thinners and in motor vehicle exhaust. It is also present in emissions from volcanoes, forest fires and crude oil. It has been detected at low levels in surface water, groundwater, drinking-water and soil samples (United States National Library of Medicine, 1997). 

Jo W-K, Song K-B (2001) Exposure to volatile organic compounds for individuals with occupations associated with potential exposure to motor vehicle exhaust and/or gasoline vapor emissions. Sci Total Environ 269(l-3) 25-37... 

Olefins, C2-C6 Photochemical degradation emissions refinery emissions Motor vehicle exhaust diesel... 

The issue of atmospheric deposition as a transport mechanism for nutrients to coastal shelf seas is a relatively recent one. However, it has now emerged as being of great importance for the following reasons. Firstly, this method is very significant in a quantitative sense (Rendell etal., 1993 Asman etal., 1995). Secondly, the deposition of material frequently occurs some way out to sea (Jickells, 1995), where the impact of biological processes in the immediate coastal zone has already reduced nutrient concentrations to undetectable levels. Particular sources of nutrients include agricultural emissions from livestock and motor vehicle exhaust fumes. 

EXPOSURE ROUTES Inhalation (cigarette smoke, motor vehicle exhaust, evaporated gasoline, emissions from burning coal and oil) Ingestion (contaminated drinking water) absorption occupational exposure. 

EXPOSURE ROUTES primarily by inhalation adsorption through eyes and skin ingestion cigarette smoke emissions from burning coal and oil motor vehicle exhaust evaporation of gasoline at service stations occupational exposure drinking of contaminated water... 

Beginning in the 1920s, the compound tetraethyl lead was added to gasoline to improve performance. Unfortunately, the lead showed up in motor vehicle exhaust, where its inhalation posed a serious health hazard. In response to this problem, the Clean Air Act mandated a reduction in lead emissions. It was also discovered that lead in motor vehicle exhaust tended to coat the surface of the catalyst in the catalytic converter, rendering the catalyst ineffective. To remedy both problems, unleaded gasoline was introduced in 1974. Leaded gasoline continued... 

Fraser M, Cass G, Simoneit B (1999) Particulate orgartic compounds emitted from motor vehicle exhaust in the atmosphere. Atmos Environ 33 2715—2724 Garg B, Cadle S, Mulawa P, Groblicld P, Laroo C, Parr G (20(X)) Brake wear particulate matter emissions. Environ Sci Technol 34 4463-4469... 

When the lead content of motor gasolines is restricted, refiners must turn to other means of octane improvement in order to maintain the octane quality of their gasolines. The most widely used approach is to increase the amount of high-octane aromatics in gasoline. This will increase the polynuclear aromatics (PNA—sometimes referred to as polynuclear aromatic hydrocarbons or PAH) and the reactive smog-forming constituents in vehicle exhaust emissions. 

The most important natural source of atmospheric carbon monoxide is the combination of oxygen with methane (CH4), which is a product of the anaerobic decay of vegetation. (Anaerobic decay takes place in the absence of oxygen.) At the same time, however, carbon monoxide is removed from the atmosphere by the activities of certain soil microorganisms, so the net result is a harmless average concentration that is less than 0.12 to 15 ppm in the Northern Hemisphere. Because stationary source combustion facilities are under much tighter environmental control than are mobile sources, the principal source of carbon monoxide that is caused by human activities is motor vehicle exhaust, which contributes to about 70% of all CO emissions in the United States. 

Serious research in catalytic reduction of automotive exhaust was begun in 1949 by Eugene Houdry, who developed mufflers for fork lift trucks used in confined spaces such as mines and warehouses (18). One of the supports used was the monolith—porcelain rods covered with films of alumina, on which platinum was deposited. California enacted laws in 1959 and 1960 on air quality and motor vehicle emission standards, which would be operative when at least two devices were developed that could meet the requirements. This gave the impetus for a greater effort in automotive catalysis research (19). Catalyst developments and fleet tests involved the partnership of catalyst manufacturers and muffler manufacturers. Three of these teams were certified by the California Motor Vehicle Pollution Control Board in 1964-65 American Cyanamid and Walker, W. R. Grace and Norris-Thermador, and Universal Oil Products and Arvin. At the same time, Detroit announced that engine modifications by lean carburation and secondary air injection enabled them to meet the California standard without the use of catalysts. This then delayed the use of catalysts in automobiles. 

Evaluation of Catalysts As Automotive Exhaust Treatment Devices," Report of the Catalyst Panel to the Committee on Motor Vehicle Emissions, National Academy of Sciences, Washington, D.C., 1973. 

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