They can be caused mainly by motor vehicles, freight trains and surprisingly, planes. Exhaust releases pollutants into the air, such as nitrogen oxides, sulfur dioxide, and a more commonly know carbon monoxide. The toxins affect significantly vital organs, including the lungs, the heart, and the brain. These chemicals also break down the ozone layer of the Earth. The ozone layer is responsible for protecting us from the harmful UV rays of the Sun. Cutting down on fossil fuels, use of Eco friendly cleaning products, and avoiding the use of pesticides can contribute to stopping the depletion of the ozone and cut down on our carbon footprints. Another option would be to ban the use of nitrous oxide. Nitrous oxide is an extremely harmful compound to the ozone layer, increasing its breakdown. It is used commonly in medicine as an anesthetic, and not uncommonly in food processing. With effort and working together exhaust fumes can be reduced