chlorofluorocarbons, definition of

A family of chemicals composed primarily of carbon, hydrogen, chlorine, and fluorine; CFCs were used mostly as refrigerants for freezers, refrigerators, and air-conditioning units, and as industrial cleansing solvents primarily in the high-tech industry. They were also used as an expansion agent in the manufacture of isocyanurate thermal insulation, and some extruded polystyrene foam used for thermal insulation, and some extruded polystyrene foam used for thermal insulation products, and food service containers.

Ozone problem
 
 CFCs' ability to destroy stratospheric ozone through catalytic cycles contributed to the depletion of ozone worldwide. Because CFCs are such stable molecules, they do not easily react with other chemicals in the lower atmosphere. One of the few forces that can break up CFC molecules is ultraviolet radiation, however the ozone layer protects the CFCs from ultraviolet radiation in the lower atmosphere. CFC molecules can then to migrate intact into the stratosphere, where the molecules are bombarded by ultraviolet rays, causing the CFCs to break up and release their chlorine atoms. The released chlorine atoms participate in ozone destruction, with a single atom of chlorine destroying ozone molecules over and over again.
 
 International attention to CFCs resulted in a meeting of diplomats from around the world in Montreal in 1987. A treaty was forged that called for drastic reductions in the production of CFCs. In 1990, diplomats met in London and voted to significantly strengthen the Montreal Protocol by calling for a complete elimination of CFCs by the year 2000.

• Mystery of banned CFCs resurgence may be solved
  The world recently learned that chlorofluorocarbons (CFCs), an ozone-damaging industrial gas banned under the 1997 Montreal Protocol, have made an unexpected comeback, with significant emissions detected in the atmosphere...
• Levels of ozone-destroying CFCs are mysteriously rising
  Globally banned by the Montreal protocol in 1987 for their ozone-destroying properties, chlorofluorocarbon (CFC) chemicals are experiencing a comeback. In recent years, levels of CFCs have increased suddenly and mysteriously. Now, scientists are racing...
• The Earth’s Ozone Layer Increases for the First Time in 35 Years
  Good news, everyone - a new United Nations report shows that the Earth's ozone layer has increased for the first time in 35 years. The report credits the recovery in part to the phasing out of chlorofluorocarbons (CFCs) following the Montreal Protocol...