Pollutants Produced by Automobiles

Engines are inefficient in more ways than just losing heat. One of the major concerns inherent in engine inefficiency is
the polluting emissions created by automobiles, especially now that they have become so prolific throughout the world. Emissions do not merely refer to the exhaust pollutants, but also to evaporative pollution.


Exhaust Emissions

In so-called "perfect combustion," all the hydrogen and carbon in the fuel would be converted to water and carbon
dioxide, respectively, by the oxygen in the air, thus releasing few pollutants. Obviously, engines in reality are not capable of this "perfect" combustion, so they emit hydrocarbons, nitrogen oxide, carbon monoxide, and carbon dioxide.

Colorado State

Evaporative Emissions

Evaporative emissions refer to the vaporization of gasoline from a number of causes:
  1. The gasoline gets heated in the fuel tank as the day grows warmer, causing it to vaporize and vent from the tank.
  2. Heat from the engine and exhaust system vaporize gasoline while the engine is running.
  3. After the engine is turned off, it takes a while to cool, so the remaining heat continues to vaporize gasoline.
  4. When refueling the car, liquid gas forces the ever-present gas vapors out of the tank.
Since gasoline is composed of hydrocarbons, evaporative emissions pose a potential environmental threat as well as decreasing fuel efficiency in automobiles.

The Plus Side?

Some of these pollutants are "green house gases" which are thought to contribute to global warming. Thus, Alaska is theoretically getting warmer every year as a result of inefficient engine emissions! I think I'd rather have clean air, myself...

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