World Ozone Day

World Ozone Day is celebrated every year on 16th September since 1995. This Day marks the importance of Ozone layer and its role in the environment. The United nations General Assembly has designated this Day to reflect the adoption of Montreal Protocol on substances that deplete the Ozone layer.

There are numerous activities and programs organized to spread awareness about the global phenomenon of Ozone layer depletion. All member nations of the Montreal protocol take this opportunity to take some concrete steps at their national level in accordance with the aims and objectives of Montreal protocol.

Ozone and its Depletion

The primary source of energy requirements on earth is the Sun. The sunlight reaching Earth contains three main radiations:

* Infrared

* Ultraviolet

* Visible.

Ultraviolet light is an electro-magnetic radiation that has wavelength smaller than that of visible light. Harmful effects of UV (ultra violet rays) include:

* Direct exposure to ultraviolet radiations cause sunburn, skin cancer and premature ageing of skin.

* Direct gazing of ultraviolet radiations is hazardous to the eyes, and exposure can cause welder's flash (photokeratitis or arc eye) and may lead to cataracts, apterygial, and pinguecula formation.

* Many popular polymers used in consumer products often get degraded with exposure to Ultra-violet radiations. Special UV absorbers should be used to protect them from attack, more so if they are supposed to be used in outdoors

It is Ozone layer that absorbs 93 % of the harmful, high frequency Ultra-violet radiations. The layer was discovered in 1913 by Charles fabric and Henri Buisson. This layer is mainly located in the lower portions of the Stratosphere.

The thickness of Ozone layer varies across different regions, it is less dense above the equator and this density increases increases while moving towards the poles. The amount also varies with season, as the amount is more in winters as compared to summers.

Ozone layer depletion:

The Ozone molecules (O3) can be damaged by free radicals like hydroxyl, chlorine, bromine, and nitric oxide. There are many sources of production of these particles. While, there are many natural sources that automatically produce these radicals, there are certain artificial compounds like chlorofluorocarbons and bromoflurocarbons that have tendencies to damage Ozone molecules.

These radicals have capacity to rise above the stratosphere and each radical is then free to initiate and catalyze a chain reaction capable of breaking down over 100,000 Ozone molecules.

Unfortunately, with the growing industrialization and commercialization, many products and processes release these radicals in the atmosphere and there number is exponentially increasing. Inspite of this basic chemical knowledge, all modern appliances like refrigerator, fire extinguisher, air conditioners use chloroflurocarbons in them.

Ozone Facts

* From 1956 to 1970 the density of the Ozone layer was nearly 280 to 325 doveson which in 1994 got reduced to mere 94 doveson. The density has been on a decline since then.

* The recent report of the Inter-governmental Panel on Climate Change (IPCC) states that Earth's temperature has increased by 0.74% in the past hundred years. Its effects are disastrous like:

1. Unexpected increase in the sea level that can submerge low lying regions including UK

2. The melting of glaciers like Himadri in India, which will first result in floods and then a long lasting drought

3. Exposure to ultra-violet rays can up the risk of cancers

4. Unexpected climatic changes

* Data from NASA's Earth-observing Aura satellite show that the Ozone hole peaked in size on Sept. 13’2007, reaching a maximum area extent of 9.7 million square miles – just larger than the size of North America.

* The Antarctic Ozone hole was discovered in 1985 by British scientists Joesph Farman, Brian Gardiner, and Jonathan Shanklin of the British Antarctic Survey.

* On September 12, 2008, the Antarctic Ozone hole reached its maximum size for the year. The Ozone hole covered about 27 million square kilometers, making it larger than North America, which is about 25 million square kilometers. Though larger than it was in 2007, the 2008 Ozone hole was still smaller than the record set in 2006.