ozone layer depletion - causes of ozone layer depletion

Depletion of ozone layer

Ozone is highly reactive molecule containing three oxygen atoms. Ozone present at the higher levels of the atmosphere (stratosphere) is a product of UV-radiation acting on Oxygen molecule. The higher energy UV -radiation split some oxygen molecules into free oxygen atoms. These atoms then combine with the molecular oxygen to form ozone.

A naturally occurring layer of ozone at high altitude absorbs damaging ultraviolet radiation from Sun. 

Therefore, this ozone layer is important for life forms on the earth. What is worrying to scientists is that amount of ozone in the stratosphere has dropped rapidly in the recent past. This decrease caused by synthetic chemical like chlorofluorocarbons (CFCs) which are used widely in air conditioners, refrigerators and in fire extinguishers. The depletion of ozone in the stratosphere occurs due to reaction between ozone and CFC.

The thin ozone layer allows UV- radiations to reach earth's atmosphere. These radiations eventually cause injury to all types of organisms on the earth as well as to the aquatic life. Besides this, thinning of ozone layer has resulted in increase in Earth's temperature and reduction in rainfall thus disturbing the ecosystem. One percent reduction in ozone increases UV- radiation on earth by 2%. It has also increased the risk of skin cancer, eye diseases and loss of immunity.

One molecule of chlorofluorocarbon can damage 1,00,000 molecules of ozone. Already so much ozone has been damaged that even if the production of CFCs is stopped, it may take several decades for ozone to recover to its normal levels. Therefore, in an attempt to protect ozone layer, the United Nations environment programme (UNEP) signed an agreement in 1987 among its member countries to phase out CFC production by 2010. This agreement is popularly known as Montreal protocol.