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.

World Ozone Day Video

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