The Secret Star of Smog Control: The Catalytic Converter

In order to comply with EPA regulations on car emissions and exhaust, the catalytic converter was born. The catalytic converter works to reduce the toxic nature of the exhaust and makes the emissions less poisonous to humans and crops; it basically cleans the gas as it passes through the exhaust system. The catalytic converter is a true environmental success story.

Because of the smog problems in Los Angeles in the 1940s, engineers became increasingly concerned with finding a cure to the problem of toxic air pollution by cars. The prototype was invented in the 1950s, but the catalytic converter that we know today was not invented until 1973.

The so-called three way catalytic converter replaced the two-way converter in 1981, and has been used on car emission systems in the U.S. since then. In a nutshell, the converter reduces nitrogen oxides, converts carbon monoxide to carbon dioxide, and oxidizes hydrocarbons into carbon dioxide and water – a much less toxic combination of chemicals than those released from cars not equipped with converters.

Unleaded fuel is required in any cars equipped with catalytic converters, because the lead in leaded fuel can coat the converter, which results in malfunction. Once lead gets into a converter, it is nearly impossible to remove.

The converter’s catalyst compounds are platinum, palladium, and rhodium. Such metals have high market value and explain why catalytic converters are often targets for thieves. Converters that are most at risk for theft typically are higher off the ground and more easily accessed, or they have bolts that can be more quickly removed.

While the converter is still considered a simple yet crucial advancement in technology, it is not without its drawbacks. Cars still cause pollution, especially sport utility vehicles that get poor mileage. Although the catalytic converter spits out carbon dioxide (CO2) instead of monoxide, and although it reduces nitrous oxides, both CO2 and nitrous oxides are major contributors to the greenhouse gas effect and global warming.

The Environmental Protection Agency states that cars in the U.S. emit 96 percent less carbon monoxide and 98 percent fewer hydrocarbons than their counterparts before 1975. Without catalytic converters, scientists believe that by now the entire country would have been under a thick sheet of smog and carbon monoxide that would be catastrophic for humans, animals, and plant life. Fortunately, this grim picture never became a reality because of tough emissions standards and millions of catalytic converters everywhere.