Motor vehicles, exhaust systems

Outdoor air is generally less polluted than the system return air. However, problems with reentry of previously exhausted air occur as a result of improperly located exhaust and intake vents or periodic changes in wind conditions. Other outdoor contamination problems include contaminants from other industrial sources, power plants, motor vehicle exhaust, and dust, asphalt vapors, and solvents from construction or renovation. Also, heat gains and losses through the building envelope due to heat conduction through exterior walls, floor, and roof, and due to solar radiation and infiltration, can be attributed to effects from external sources. 

Catalytic treatment of motor vehicle exhaust has been applied in all passenger cars in the USA since the 1975 models. The first cars with electronic feedback systems and three-way catalysts were 1979 Volvos, sold in California. Today all new gasoline cars sold in the Western world are equipped with catalytic converters. It... 

Food contaminated from leaching of glazes of ceramic food ware, as well as from motor vehicle exhausts, atmospheric deposits, canned foods, and water supply from plumbing system Fish and shellfish meat from animals fed with mercury-dressed grains... 

Carbon monoxide (CO) poisoning remains the single most common cause of fatal poisoning in developed, Western countries and most probably in the rest of the world as well. Motor vehicle exhausts, defective heating systems and smoke from all types of fires are common sources. Some 40% of an absorbed dose of dichloro-methane is also metabolized to CO. 

For pollutants in the form of a gas the dispersion is very rapid for the usual weather conditions and the exposure decreases with distance from the vehicle exhaust systems. Thus the people exposed to the greatest levels of pollution are first of all the drivers of the motor vehicles, then those making use of two-wheeled vehicles and finally the pedestrians. 

Furthermore, the level of lead in blood does not appear to be a reliable measure of absorption of tetra-ethyl lead, which tends to dissolve and concentrate in lipids so that the brain and nervous system can be affected to an extent which is not reflected by the increase in blood level. Any attempt to monitor the effects on health of the discharge of lead from motor vehicle exhausts which is... 

We have included in this volume two chapters specifically related to society s kinetic system. We have asked James Wei of the University of Delaware, recent Chairman of the consultant panel on Catalyst Systems for the National Academy of Sciences Committee on Motor Vehicle Emissions, to illustrate key problems and bridges between the catalytic science and the practical objectives of minimizing automobile exhaust emissions. We have also asked for a portrayal of the hard economic facts that constrain and guide what properties in a catalyst are useful to the catalytic practitioner. For this we have turned to Duncan S. Davies, General Manager of Research and Development, and John Dewing, Research Specialist in Heterogeneous Catalysts, both from Imperial Chemical Industries Limited. 

Emission control from heavy duty diesel engines in vehicles and stationary sources involves the use of ammonium to selectively reduce N O, from the exhaust gas. This NO removal system is called selective catalytic reduction by ammonium (NH3-SGR) and it is additionally used for the catalytic oxidation of GO and HGs.The ammonia primarily reacts in the SGR catalytic converter with NO2 to form nitrogen and water. Excess ammonia is converted to nitrogen and water on reaction with residual oxygen. As ammonia is a toxic substance, the actual reducing agent used in motor vehicle applications is urea. Urea is manufactured commercially and is both ground water compatible and chemically stable under ambient conditions [46]. 

Hopke, et al. (4) and Gaarenstroom, Perone, and Moyers (7) used the common factor analysis approach in their analyses of the Boston and Tucson area aerosol composition, respectively. In the Boston data, for 90 samples at a variety of sites, six common factors were identified that were interpreted as soil, sea salt, oil-fired power plants, motor vehicles, refuse incineration and an unknown manganese-selenium source. The six factors accounted for about 78 of the system variance. There was also a high unique factor for bromine that was interpreted to be fresh automobile exhaust. Large unique factors for antimony and selenium were found. These factors may possibly represent emission of volatile species whose concentrations do not oovary with other elements emitted by the same source. 

Most LNG vehicles provide a manifold to capture natural gas vented from the LNG tank and direct it to a safe location outside of the vehicle, usually near the top of the vehicle where the vented natural gas will rise and dissipate safely. For vehicle maintenance facilities, exhaust systems with explosion-proof blowers and motors should be provided. When the vehicle is brought inside for maintenance, the exhaust system hose is placed over the LNG vent and the system is turned on. Any vented natural gas vapor is then safely removed from the building. For vehicle parking facilities, this is usually not a practical solution fc - cost and implementation reasons. 

The larger concern about nitro-aromatic compounds is that environmental exposure to these molecules can cause cancer in humans and in other living organisms. Nitro-aromatic compounds are acutely toxic, mutagenic, and carcinogenic in laboratory mammals and in vitro test systems [6, 8]. Despite the potential negative impact of nitro-aromatic compounds on human health, they continue to be emitted into ambient air from municipal incinerators [9], motor vehicles (particularly from diesel exhausts) [10, 11], industrial power plants [12], and other sources. Evidence... 

Heavy metals concentration generally decreases in urban soils away from the main road network and with increasing depth of sampling. This can be explained by the strong dependence of these contaminants on the use of motor vehicles—leaded fuels for Pb, tire wear for Zn and Cd, brake pads for Sb, converters and exhaust systems for platinum group elements (PGEs). 

Catalytic technologies are usually employed to deal with pollutants emitted by the exhaust systems of motor vehicles and which are subject to regulation (nitrogen oxides, hydrocarbons, CO and particulates). Specific catalysts have been developed in each case as a function of the regulatory requirements and particular characteristics of the emission. Thus, three-way catalysts are highly efficient at controlling emissions produced by engines... 

One result is that air pollution is an increasingly common phenomena necessitating aggressive motor vehicle pollution control efforts. The purpose of this report is to survey what is presently known about transportation related air pollution problems, to summarize the adverse impacts which result, to review actions underway or planned to address these problems, and to estimate future trends. Based on these trends, this study wilt assess the large and growing vehicle pollution control market, expecially with regard to exhaust after treatment systems. 

Avoid producing pyrotechnic dust in areas around motor vehicles (hot exhaust systems). 

From the literature, it is clear that the identified emission and fuel consumption models take into account the various factors affecting emissions and fuel consumption rate in automobile. It is further established that these factors have affected vehicular emissions and fuel crmsumption in varying degree. However, efforts on fuel consumption have since crmtinued but still the effects of a leakage on any part of the exhaust system in relation with fuel cmisumption rate have not been investigated. Sequel to this, effects of leaks oti the motor vehicle, specifically on... 

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