A catalytic converter is a device installed in automobiles that is designed to reduce harmful emissions released from the vehicle’s exhaust. In the United States, all vehicles produced after 1975 are required to have a catalytic converter. This is part of an attempt to reduce air pollution.

Without a catalytic converter, the emissions from automobiles consist of noxious gases such as carbon monoxide, hydrocarbons and nitrogen oxide. These gases emitted from automobiles are the largest source of ground level ozone. Ground level ozone is responsible for smog, myriad respiratory problems and damage to plant life. A catalytic converter uses metallic catalysts, usually platinum, rhodium or palladium, that cause a chemical reaction with the noxious gases, converting them into less harmful gases.

The catalytic converter was developed in the 1960s, and by the 1970s, most vehicles were equipped with one. In 1975, the United States’ Clean Air Act required a 75% emissions reduction on all new model vehicles, which was to be achieved with the use of a catalytic converter. The catalytic converter is constantly being improved upon and is now more efficient than ever. In the US, these improvements are in accordance with the Environmental Protection Agency’s (EPA) more stringent amendments to the Clean Air Act.

Although the catalytic converter has been very successful in reducing the dangerous pollutants released by automobiles, particularly ground level ozone, it has fallen under criticism. The catalytic converter may help to solve one serious environmental problem, but its use is a trade-off at the expense of increasing global warming. The catalytic converter creates and releases into the atmosphere gases that are responsible for global warming. Carbon dioxide, which is released along with the noxious gases from the vehicle’s exhaust system, is increased by the catalytic converter. Carbon monoxide, which is transformed into carbon dioxide, is harmless to humans and plant life, but it is responsible for absorbing the sun's infrared waves and causing the planet to warm up.