In traditional internal combustion engines, the series of small explosions that keeps the engines running also produce gases such as carbon monoxide, carbon dioxide, and nitrogen oxide, all of which can be harmful or even deadly to people or animals. In the enclosed spaces of a vehicle’s compartment, the occupants could become ill or die from breathing in these fumes. However, the exhaust system is designed to remove these pollutants from the vehicles and to expel them into the outside air.