Behindwoods : The big hole in the sky

The big hole in the sky Article By : Ramaa Location : Chennai E - Mail Id : behindw@behindwoods.com

Life on Earth depends on oxygen in the atmosphere. Another variant of oxygen is ozone. The atmosphere contains ozone at a height of about 10-50 kms from the Earth’s surface. This layer plays the important function of filtering the harmful ultra-violet rays from the sun. These rays are potentially carcinogenic and can cause congenital abnormalities also. During the
1970s, scientists suggested that oxides of nitrogen which are emitted from factories and aerosols from supersonic planes could pose harm to the ozone layer. Professors Sherwood Rowland and Mario Moleno discovered that Chlorofluorocarbons (CFCs)from refrigerators and air-conditioners would react with the ozone layer and release free radicals
harmful to human life. Ozone reacts with halocarbons like CFCs, Methyl chloroform; Hydrobromofluorocarbon, Methyl Bromide etc., and the free radicals are dispersed. This causes reduction in thickness of the ozone layer which is popularly called the hole in the ozone layer. Due to the gap in the layer, ultra-violet rays can easily reach the Earth. The 1985 Vienna Convention and 1987 Montreal Convention have laid down strict guidelines for the use of CFCs. According to these conventions, the use of CFCs should be reduced substantially by 2010. Let us take a pledge to protect the ozone layer.