Cars are sources of air pollution problems, most of which are important from the vehicle. Carbon monoxide, hydrocarbons, nitrogen oxides And sulfur About 55% of the hydrocarbons from the exhaust woven 25% from crankcase and 20% of the volatility in the carburetor. And fuel tanks Oxides of nitrogen is Nitric oxide (NO), nitrogen dioxide (NO2) and nitrous oxide (N2O) is almost entirely out of the exhaust.