About 30 countries decided in the Montreal Protocol, that they would reduce usage of chlorofluorocarbons (CFCs) by 50 per cent in the year 2000 and completely avoid use of CFCs by 2010. Hence, on the Ozone Day when environmentalists will talk about the success of their efforts. Ozone, which serves as a protective layer in the atmosphere about 45 kms from the surface of the earth, is affected by release of some man-made chemicals like CFCs, carbontetralchloride and methyl chloroform, which are ozone-depleting substances. When the ozone layer becomes thin, it allows ultraviolet radiation to reach the earth, which can cause skin cancer, cataracts and other infections. The depletion of the layer may lead to changes in temperature, sharp decrease in the population of fish and other aquatic organisms and also decrease agricultural output.

India joined the protocol in 1992. Ozone Monitoring Cells have been set up in every state by pollution control boards. The cells enumerate the number of industries using ozone-depleting substances (ODS). In Tamil Nadu, there are about 55 industries which have produced 1276.29 tones of ODS up to 1994. According to a WHO report, more than 50,000 persons have lost their lives because of ozone depletion in India up to 1995.