Bengaluru, Sep 17 (IANS): The state-run postal department on Wednesday released a special cover to mark 'World Ozone Day 2020' at a function here in the presence of Karnataka Minister for Forests and Ecology Anand Singh, and other officials.

"The special postal cover marks the theme for 2020 'Ozone for Life - 35 years of Ozone Layer Protection', which is observed on September 16 every year," said state chief postmaster general Sharda Sampath in a statement here.

Sponsored by the Karnataka State Pollution Control Board, the special cover will be available for sale at philatelic bureaus of the main post offices in the city, Mangaluru, Mysuru and Belagavi across the southern state.

"The Ozone day is celebrated to remind the people on the decline of the Ozone layer, to take steps to prevent it and protect the earth," said Sampath on the occasion.

The United Nations General Assembly proclaimed the World Ozone Day as the international day for preserving the Ozone layer on December 19, 2000, in commemoration of the date in 1987 when nations signed the Montreal Protocol on substances that deplete the Ozone layer was signed in Canada.

The Ozone shield is a delicate layer of gas in the earth's stratosphere that absorbs most of the sun's ultraviolet and other harmful rays.

The radiation layer is found in the lower stratosphere, which is 15-35 km above earth, with its thickness varying seasonally and geographically.

French physicists Charles Fabry and Henri Buisson discovered the Ozone layer in 1913.

In 1976, it was found that industrial chemicals like chlorofluorocarbons (CFCs) cause depletion of the Ozone layer, leading to increase in ultraviolet radiation, which is a threat to life on the planet.

The research led to ban chemicals and Ozone depletion was slowed.

Union Minister of Environment, Forest and Climate Change Prakash Javadekar said the World Ozone Day was observed to create awareness related to climate change and ozone depletion.

"I urge people to look for ozone-friendly, HCFC free, energy-efficient appliances to minimise the Ozone layer impact," said Javadekar in a tweet on the occasion.

BJP Lok Sabha member from Rajasthan Rajyavardhan Rathore tweeted: "Let not the patience of atmosphere wear thin. Ozone shield is a natural umbrella that protects the earth against harmful UV radiations. CFC gases damage the shield. Being 'Vocal for Local' is Ozone-friendly as lesser transportation entails lesser nitrous oxide emitted."