Automobile emissions control

From ArticleWorld

Automobile emissions control refers to the various measures that are carried out to keep check on vehicle exhausts, so as to lessen their detrimental effect on the environment. Air pollution is a cause for growing concern around the world, since it can bring about a variety of problems for not just humans, but also the entire ecosystem. Most of the world’s air pollution originates from automobile exhaust. This is why numerous techniques have been devised to cut down the concentrations of harmful pollutants given out by them.

Emissions control measures have been adopted all around the world. There has been fairly good response to local and national legislation enforcing rules to limit vehicular pollution. However, with the ever increasing number of vehicles on the roads of both developed and underdeveloped countries, real progress in bringing down air pollution levels has been slower than expected.

Types of emissions

There are two categories of pollution-causing emissions from automobiles, tailpipe emissions (exhaust) due to combustion of fuel, and evaporative emissions arising out of the evaporation of fuel. Automobile exhausts contain a number of gases that are harmful to living beings. Hydrocarbons, which arise out of incomplete combustion of fuel, can cause smog in congested cities. Oxide gases of nitrogen and sulphur are highly poisonous and are known to cause breathing problems. They result in acid rain, causing damage to plant life and defacing structures built of marble.

The most dangerous gas given out in exhaust is carbon monoxide, which can kill a human being even if a small concentration of the gas is inhaled. Another gas, carbon dioxide, contributes significantly to the ‘greenhouse effect’ which causes global warming.

Control of automobile exhaust pollution

To check pollution, it is important to ensure that fuel combustion is complete and the products of combustion are not harmful. There are several methods of controlling pollution from automobile exhausts. Prominent among them are:

• Improving engine efficiency: The engine of an automobile should be spruced up to give better performance. Recent improvements in electronic ignition systems by vehicle manufacturers have led to good reductions in emission levels. Fuel injection systems and carburettor designs have also been enhanced, leading to better utilization of fuel. Spark optimizers in petrol engines, for instance, ensure complete burning of petrol-air mixtures. Automatic fuel control is done in most modern cars, with an engine control module at the centre.

• Improving overall vehicle efficiency: The overall efficiency of vehicles can be increased by better streamlining of the body design and improved lubrication of bearings. Also fuel consumption can be minimised by proper driving habits, obstruction-free roads and reduction in the number of ‘start-and-stops’.

• Treating emissions: The exhaust gases can be treated in a number of ways. Recirculation of the tailpipe gases can ensure complete burning of poisonous carbon monoxide into the less-harmful carbon dioxide. Catalytic converters in exhaust pipes help convert polluting gases into non-polluting ones.

Control of evaporative emissions

Evaporative emissions are a major contributor to smog, which can hamper visibility and cause lung problems.

Steps should be taken to prevent the escape of vapours from fuel tanks. Vapours must be channelled to reach the combustion chamber only. Precautions should be taken while refuelling also. Nozzles of pumps at petrol stations should be designed to prevent spillage and evaporation losses.