Unfortunately, that is not the only consequence of combustion. Fuel is usually not burned cleanly or completely because it may contain impurities, other chemicals which produce dangerous pollutants, and may not be burned efficiently. Fossil fuels, coal, oil, and natural gas, contain such impurities. Pollution such as carbon monoxide, a colorless and odorless gas, nitrogen oxide, sulfur dioxide, and hydrocarbons are produced by polluters such as vehicles, especially in heavy city traffic, and factories. The result is smog and other atmospheric pollution.
Sulfur dioxide leads to acid rain, which can spread to the water as well.