CFCs, or Chlorofluorocarbon, are one of many chemical substances that have been invented during the 19th century. At the end of world War II, an American engineer named Thomas Midgely discovered CFCs.
CFCs were created to replace Ammonia, Chlomelthane, and Sulfurdioxide which is use for refrigerants, propellants, and cleaning solvents. These three substances are more toxic to human and animals then CFCs.
Nowadays people can find CFCs in many products, such as spray cans, electronic cleaners, air-conditioners, refrigerators, and in medical supplies which use air pressure for asthma patients.
In 1970, Sherwood Roland and Mario discovered that CFCs have damaged the world's atmosphere, particularly the stratosphere which is 10-30 kilometers above the ground. It helps protect the world from 70-90% of ultraviolet(UV) rays. If too much ultraviolet radiation passes through the atmosphere it can cause skin cancer in humans. It also affects the world's temperature. CFCs will rise into the atmosphere and react with UV rays, becoming a chorine radical which is toxic and can destroy the atmosphere. One atom of chorine can damage about one thousand ozone molecules. The reduction of ozone by noly 1% could possibly increase the cases of skin cancer by about ten thousand per year and it could change the habitats of living creatures all over the world.