Automobile Pollution

AUTOMOBILES

        Motor emissions contribute to air pollution and are a major ingredient for *smog in some large cities. A recent 2013 study by MIT (Massachusetts Institute of Technology) indicates that 53,000 early deaths occur per year in the United States because of the vehicle emissions. According to the study of the same university, traffic fumes alone cause the death of 5000 people per year just in the United Kingdom.

*smog - smoke or other atmospheric pollutants combined with fog in an unhealthy or irritating mixture.

- Cold Engines
          During the first two minutes after starting the engine of a car that has not been operated for several hours, the amount of emissions can be very high. This occurs for two main reasons:

1. Rich air-fuel ratio requirement in cold engines:
When a cold engine is started, the fuel does not vaporise completely, creating higher emissions of hydrocarbons, nitrogen oxide and carbon monoxide, which reduces only as the engine reaches operating temperature. 

The duration of this start-up phase has been reduced by advances in materials and technology, including computer-controlled fuel injection, shorter intake lengths, and pre-heating of fuel and/or inducted air.

2. Inefficient Catalytic converter under cold conditions:
 Catalytic converters are very inefficient until up to their operating temperature. 

This time has been much reduced by moving the converter closer to the exhaust manifold and even moreso placing a small yet quick-to-heat-up converter directly at the exhaust manifold. The small converter handles the start-up emissions, which allows enough time for the larger main converter to heat up. 

Further improvements can be realised in many ways, including electric heating, thermal battery, chemical reaction preheating, flame heating and superinsulation.

sources: www.dictionary.com
               http://en.wikipedia.org/wiki/Exhaust_gas
               www.google.com (google images)