A catalytic converter is a device in the exhaust pipe of a car, near its engine. It is used to clean up the exhaust the car sends out into the atmosphere. It works by using a catalyst material, usually made of Platinum, Palladium, and Rhodium. The catalytic converter converts carbon monoxide, hydrocarbons, and nitrogen oxides, all of which make the air dirty and make people sick, into carbon dioxide, water, and Nitrogen, all of which are less harmless. These chemicals, however, are still large contributors to global warming. A catalytic converter reduces carbon monoxide by contacting it with oxygen, creating carbon dioxide, which is less harmful. Because hydrocarbons are unburned fuel particles that are put into the catalytic converter, they burn up in the catalytic converter, making it very hot.