Motor vehicles atmospheric pollution

Acid deposition has been known to exist since early in the industrial age. The principle pollutants responsible for the elevated levels of acidity are the oxidized forms of sulphur and nitrogen that have been emitted as by-products from non-ferrous smelters, fossil-fueled power generating stations, and motor vehicles. The pollutants are transported substantial distances from the source areas by the atmosphere. They are deposited on receptor regions remote from the sources as acidic rain, snow, and fog or as gasses and dry particulates. 

The presence of polycyclic aromatic hydrocarbons in the environment is of obvious concern and, apart from specific occupational environments, human exposure to these compounds derives from combustion products released into the atmosphere. Estimates of the total annual benzo[aJpyrene emissions in the United States range from 900 tons (19) to about 1300 tons (20). These totals are derived from heat and power generation (37-38%), open-refuse burning (42-46%), coke production (15-19%) and motor vehicle emissions (1-1.5%) (19,20). Since the vast majority of these emissions are from stationary sources, local levels of air pollution obviously vary. Benzo[aJpyrene levels of less than 1 pg/1,000 m correspond to clean air (20). At this level, it can be estimated that the average person would inhale about 0.02 pg of benzo[aJpyrene per day, and this could increase to 1.5 pg/day in polluted air (21). 

Research dating back to the mid 1950 s has shown that volatile orgamc compounds (VOC s) photochemically react m the atmosphere and contribute to the formation of ground level ozone, a precursor to smog [1]. Medical studies have shown that human exposure to ozone can result in eye and smus tract irritation, and can lead to respiratory related illnesses [2]. Due to the unique and severe smog problems that affected many cities in the state of California, studies of the causes of ah pollution were initiated m the 1950 s [3]. Based on its findings, California formed the Motor Vehicle Pollution Control Board m 1960 to regulate pollution from automobiles. 

Storm water runoff from cities and villages presents another problem. This runoff contains salts from road deicing, street refuse, animal waste, food litter, residue from atmospheric deposition of sulfuric and nitric acid, metals, asbestos from automobile brakes, rubber from tires, hydrocarbons from motor vehicle exhaust condensates, oil and grease, soil and inorganic nutrients from construction sites, and a variety of other chemicals. Research shows a heavy impact of urban nonpoint pollution on freshwater quality (World Resources Institute, 1988). 

Abstract Gaseous and particulate emissions from vehicles represent a major source of atmospheric pollution in cities. Recent research shows evidence of, along with the primary emissions from motor exhaust, important contributions from secondary (due to traffic-related organic/inorganic gaseous precursors) and primary particles due to wear and resuspension processes. Besides new and more effective (for NO emissions) technologies, non-technological measures from local authorities are needed to improve urban air quality in Europe. 

Emission Pollution discharged into the atmosphere from smokestacks, other vents, and surface areas of commercial or industrial facilities from residential chimneys and from motor vehicles, locomotives, or air craft exhausts. 

The pollution with dust is caused by emissions from industrial plants and traffic, as well as by high emissions from natural sources of dust. The main emission sources of nitrogen oxides are mainly the mobile ones such as motor vehicles. The relatively high level of pollution by ozone is determined by photo-chemical reactions in the atmosphere under the influence of solar radiation and the high level of ozone precursor compounds. 

Lead additives pollute the atmosphere, the ground, water, vegetation and finally animals and man. In the vicinity of roads the pollution, extends for some hundred of meters. Beyond that distance, the levels are 10 to 30 times less than the levels in urban areas but are nevertheless still mainly due to the transfer over short or long distances of pollutants due to the motor vehicles. 

In the case of road transport it is not possible to conceive any substitute for motor vehicles. Motor vehicles are used to a huge extent for collective transport, individual transport and freight. They deteriorate the quality of the environment in cities with dense traffic. At the present time, in industrially developed countries, motor vehicles contribute more than 50%-to the amounts of anthropogenic gaseous emissions polluting the atmosphere. In certain big cities and industrial agglomerations, this contribution exceeds 90%. 

For assessment of the contribution of traffic derived emissions to total pollution levels in an urban atmosphere, detailed information about the emission characteristics of motor vehicles operated under real-world conditions is needed. 

There was some surprise that a CO standard was established, since it is not involved in the sensory perception of smog however, the studies of urban pollutant concentrations showed that the levels of CO frequently exceeded those known to cause significant impairment of important bodily functions in sensitive segments of the population, specifically those with impaired respiratory or circulatory capacity. Further, although the auto was not the sole contributor to smog, source inventory data indicated that the only significant source of atmospheric CO was motor vehicle exhaust (14). 

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