CFCs or chlorofluorocarbons are those compounds that are useful as propellants in aerosol sprays, refrigerants, coolants, cleaning agents and plastic foam. They are the main eaters of ozone present in the ozonosphere. Ozonosphere is the general stratum of the upper atmosphere in which there is an appreciable ozone concentration and in which ozone plays an important part in the balance of the atmosphere.
The chlorofluorocarbons (trade named freons) released by us are stable and can live up to 100 years. They are non-toxic and harmless to life. But when they drift slowly upward to reach the stratosphere by convection, they are struck by the high-energy short wave length radiations such as ultra violet rays and this initiates a ozone clearing process. When a CFC molecule is exposed to strong UV radiation in the stratosphere, it is broken apart. This releases a chlorine atom, which attacks an ozone molecule, pulls away one of the three oxygen atoms and forms a chlorine monoxide molecule thus destroying the ozone molecule. The destructive process continues further.
The oxygen atoms from the new chlorine monoxide molecule is pulled away by free oxygen atoms freeing the chlorine atom to restart the cycle thus progressively more molecules are decomposed. It has been found that one chlorine atom can eat up to 1,00,000 molecules of ozone. A severe depletion in the ozone layer will result in an increase in the case of skin cancer, eye cataract and suppression of the immune system of humans and other species. Food crops sensitive to UV rays could also be adversely affected.
No comments:
Post a Comment