Chlorofluorocarbons (CFCs) are a group of manufactured chemical compounds that contain chlorine, fluorine, and carbon. This group includes R-134A,R-12,R-22 and many forms of Freon. They are colorless, odorless, nontoxic, nonflammable, and stable when emitted. When they are emitted and reach the stratosphere, they break apart and release chlorine atoms, which destroy the earths ozone layer. some types of CFCs can cause unconsciousness, shortness of breath, and irregular heartbeat. It can also cause confusion, drowsiness, coughing, sore throat, difficulty breathing, and eye redness and pain. Direct skin contact with some types of CFCs can cause frostbite or dry skin. When CFCs destroy the ozone layer, harmful ultraviolet rays reach the earth. Exposure to increased ultraviolet rays can cause skin cancer, cataracts, and weakened immune systems.