Passenger vehicles are a major pollution contributor, producing significant amounts of nitrogen oxides, carbon monoxide, and other pollution. In , transportation contributed more than half of the carbon monoxide and nitrogen oxides, and almost a quarter of the hydrocarbons emitted into our air. Strong federal and state policies also help.
Essay on Vehicle Pollution for Children and Students in English
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A survey conducted by Consumer Reports and the Union of Concerned Scientists showed that interest in electric cars and trucks is strong across the United States and between different income groups. Two wheelers play an important role in Asia as they are accessible to a larger portion of the population who cannot afford to own a motor vehicle. This region has a very large population of two and three wheelers that dominate the emissions inventory for some compounds in most major cities.
In some cases, the inclusion of motorized two wheelers in total motorization rates brings these motorization rates up to the same level as cities with much higher average per capita or per household incomes.
Car Parts That Pollute
For example, when motorized two wheelers are included, Mexico City, with a GDP per capita 10 times higher than Chennai, has a lower motorization rate than Chennai. As the income of individuals rises, the two wheeler becomes accessible and therefore accelerates the motorization process in Asia. A high proportion of the population in Asian cities currently depends on public transport and non- motorized forms of transport such as walking and cycling as the main mode of transport. As cities grow in area and decline in average density, the relative share of trips made by public transport and the absolute number of non-motorized trips are decreasing.
The rising trend in car ownership and decline in public transport as an alternative to the private motor vehicle has varying effects on different countries often affecting the poor, elderly and disabled who are dependent on public transport for their personal mobility. The continued growth in motorization in Asia will further exacerbate current levels of traffic congestion and result in increased motor vehicle emissions.
Among the important constituents of the petrol engine exhaust are carbon monoxide, un-burnt hydrocarbons, nitrogen oxides, particulates and lead, while diesel engine emits un-burnt hydrocarbons, nitrogen oxides, sulphur oxides, smoke and odour. The vehicle population is growing rapidly throughout the world and emissions from transportation will increase in proportion, if unchecked. Among the list of automotive pollutions serial numbers 1 to 5 is decidedly dangerous to human health while serial nos.
A comparison of exhaust constituents of petrol and diesel engines are given in Fig. The pollutants like carbon monoxide, un-burnt hydrocarbons and nitrogen oxides have been the main targets of exhaust emission regulations throughout the world, because of their potential health hazard. To obtain the mass of exhaust emission from a vehicle, it is necessary to measure the concentration of the pollutants in the exhaust and the mass flow of air through the engine.
On the whole, diesel engines are less of a health hazard than petrol engines, although the smoke and odour are certainly a nuisance. Thus automobiles are mobile polluters and petrol vehicles are the worst. The highest emission rates occur during motor idling, deceleration and at slower speeds Table Road intersections, especially those that are traffic light controlled and sharp turns in cities slow down the traffic and enhance the pollution emission rates.
During idling and at slow speeds the greatest emission is of carbon monoxide and hydrocarbons. Ozone, the principal ingredient of urban smog, is formed when energy from sunlight causes hydrocarbons to react with Nitrogen oxides NO x.
Sulfur dioxide SO 2 , Lead Pb and the Suspended Particulate Matter SPM are the other toxic pollutants from automobiles, all of which make the urban environment particularly unpleasant for the city dwellers Table Automobile pollutants have multiple effects on various environmental variables Table Among them the effect of auto-emission on plants and human health is most predominant. The polluted gases as emitted from automobile viz. In addition secondary pollutants which form smog is considered to be the most severely affectively pollutant to human health Table In urban environment, automobile emission constitute the major pollutant source.
These toxic effects of the automobile exhaust were traced back to NO x , that are solubilized in the water saturated nitric acid HNO 3. These compounds immediately dissociate into nitrate, nitrite and protons so that nitrate and nitrite accumulate in mesophyll cells of treated plants. This, in turn, induces the synthesis of a number of enzymes viz.
Essay Paper on Air Pollution in Thailand
The effect of NO x on photosynthesis and dark respiration is highly dependent on exposure time and doses. Increasing concentrations of NO x above 0. Over the years, the automobile population is increasing and thereby contributing substantially to the total urban air pollution load. For abatement of such pollution, number of practices already adopted in various countries. The details of car emission standard as practiced in India and Europe is given in the separate Tables There is wide range of techniques which can be applied to the intake system, the combustion chamber and the exhaust systems of petrol and diesel engines to reduce exhaust emissions Fig.
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The oxidation of CO and un-burnt hydrocarbons with air can be accelerated if a catalyst is present in the exhaust system. The most popular catalysts for vehicular exhaust emission control platinum and palladium. The catalyst can be introduced into the exhaust system by deposition on a ceramic honeycomb. MOEF proposed that the industry test emissions after fitting catalytic convertors, based on which government would finalize new standards for metros.
Industry found that it could meet norms that were halfway between the and norms Table While the CO standard is 8. Similarly, HC and NO x has been brought down to 2. Encouraged by these results, new norms are now being contemplated for metro areas as an intermediate measure before The automotive industry is unhappy with the fact that MOEF has allowed the Petroleum Ministry to drag its feet for so long, while it was being hammered with conditions.
Eliminating lead from petrol and reducing the sulphur content of diesel, will address the specific problems of lead particulate matter pollution and facilitate the use of catalytic convertors. But there are several other shortcomings in fuel quality in India which interfere with efficient combustion and foul up the engine.
Bad quality fuel leads to gum deposits on the engine which can clog up the carburetor passage and disturb the air-fuel ratio, thus leading to improper combustion. They claim that if fuel causes clogged passages, then engineering modifications like recirculation of blowby gas or exhaust gas for complete burning and cleaner crankcase emission will compound the problem, as the recirculated exhaust gas will leave behind more deposits.
The automotive industry complains that vehicles are tested with reference fuel, specifications for which have been separately notified.