Twenty years ago, on 16 September 1987, a group of countries signed the Montreal Protocol in a pivotal step towards protecting stratospheric ozone. According to the United Nations General Assembly, each 16 September is "International Day for the Preservation of the Ozone Layer."

For the fifth consecutive year, September 16 will be observed worldwide as International Day for the Preservation of the Ozone Layer. The United Nations first declared International Ozone Day in 1995, in commemoration of the date on which countries signed the Montreal Protocol on substances that deplete the Ozone Layer in 1987.

At the end of 1995, industrialized countries had already phased out about a million tons of consumed Ozone Depleting Substances (ODS). Phase out is well advanced in developing countries and projects are being implemented to phase out more than one third of their ODS consumption ahead of the targeted phase out date.

Ozone Depleting Substances are certain man-made chemicals containing Chlorine and Bromine, which have a high potential to deplete the Ozone Layer through chemical interactions in the earth’s stratosphere. Examples of ODS include chlorofluorocarbons (CFCs) used in refrigerators, air-conditioning units foam products and aerosol sprays and halons used in fire extinguishers.

The Ozone Layer which surrounds the earth at a height of about 25km, protects life on earth by absorbing some of the radiation from the sun thus preventing harmful ultra-violet (UV) rays from reaching the earth’s surface. The increase in UV rays has been linked to increase in some types of skin cancers, cataracts, lower plant productivity and deterioration in certain forms of marine life.