Chlorofluorocarbon << `klawr` uh `floor` uh KAHR buhn >> is any of a group of synthetic organic compounds that contain chlorine, fluorine, and carbon. The most common chlorofluorocarbons (CFC’s) are trichlorofluoromethane, also called CFC-11; dichlorodifluoromethane, or CFC-12; and trichlorotrifluoroethane, or CFC-113. Chlorofluorocarbons are sometimes referred to simply as fluorocarbons, though there are other types of fluorocarbons that do not contain chlorine.
CFC’s were once commonly used as refrigerants (cooling agents) in air conditioners and refrigerators and to make plastic foams for furniture and insulation. Some CFC’s were used extensively as propellants in aerosol spray products because they are nonpoisonous and nonflammable (under normal conditions) and they are easily converted from liquid to gas or from gas to liquid. The DuPont Company was the world’s largest producer of CFC’s, which it sold under the registered trademark Freon.
Beginning in the 1970’s, scientific studies found that CFC’s harm the environment by breaking down ozone molecules in Earth’s upper atmosphere. Ozone, a semi-stable form of oxygen, protects plants and animals from the harmful ultraviolet rays of the sun. As CFC’s reach the upper atmosphere, they break apart and release chlorine atoms. These chlorine atoms react chemically with the ozone and convert it to ordinary oxygen gas. Direct measurements over Antarctica have demonstrated that CFC’s are responsible for a “hole” that forms in the ozone layer there each spring. For more information, see Ozone hole.
The United States government banned CFC’s as propellants in aerosol spray cans in 1978. The Montreal Protocol, an international agreement adopted in 1987 by 23 countries, provided a global framework for phasing out the production of all CFC’s. In 1988, DuPont announced plans to phase out its production of CFC’s. By 2009, every country in the world had signed on to the Montreal Protocol. As a result of the rapid reduction in CFC use worldwide, the depletion of ozone in Earth’s upper atmosphere has largely stopped. In 2016, scientists announced that the ozone hole had been shrinking since 2000. However, scientists believe Earth’s ozone layer will still take many years to recover to its normal state.
