The ozone layer can be depleted by free radical catalysts like chlorine, bromine and nitrites. The concentrations of chlorine and bromine at the atmosphere has increased dramatically during recent year due to the release of large quantities of man-made organic halogen compounds especially chlorofluorocarbon (CFCs) that is used in aerosol cans, air-condition and refrigerator.
Each radical is then free to initiate and catalyze a chain reaction capable of breaking down over 100,000 ozone molecules. The breakdown of ozone in the stratosphere results in the ozone molecules being unable to absorb the dangerous ultraviolet radiation from the sun and thus reaches the Earth’s surface.
As years go by, the continent-size hole in Earth's ozone layer has been getting bigger and bigger. With less ozone in the atmosphere, more and more harmful ultraviolet radiation able to strike the Earth and resulting in changes in molecular DNA which can lead to skin cancer and changes in plant growth.
Since the discovery of CFCs causing the damage of ozone layer in 1989, most of the countries had ban the import of CFCs containing aerosol cans. In 2003, researchers announced that the international ban and the limited production of CFCs containing products had successfully slowing the rate of ozone layer depletion.
Ozone layer
