What is the ozone layer and what is its significance? Most of us have already heard of the terms "ozone layer" but do not really know or understand what it is. In simplest terms, the ozone layer is a layer of gas in the earth's atmosphere with relatively high concentrations of ozone gas. Although ozone gas also occurs close to the ground where it is known as a pollutant, 90 percent of ozone is found in the ozone layer. This layer of gas, found approximately 20-50 kilometres from the earth's surface, was discovered by French physicists Charles Fabry and Henri Buisson back in 1913.

The ozone layer plays a very important role in the existence of all life on earth - it filters out almost all of the harmful ultraviolet rays from the sun and blocks out the hazardous radiation from reaching the earth's surface. The amount and concentration of ozone in any given area of the stratosphere differs according to various factors including weather, temperature, latitude and altitude. However, it was discovered that harmful aerosols and other particles have a significant impact on the level of ozone present in the atmosphere.

In 1985, a thinning area of the ozone layer was discovered above Antarctica. This eventually progressed into an ozone hole. The discovery sparked worldwide concern over the depletion of the ozone layer especially since it was discovered that the main culprits for the deterioration of the layer are human-produced chemicals and ozone depleting substances (ODS) such as chlorofluorocarbons (CFC) liberally used in refrigerants and aerosol propellants.

The earth's ozone layer is now depleting at a fast and steady rate. This poses a serious problem since the increasing levels of UV rays in the earth cause myriad problems not only for human and animal health but also to certain materials like plastics. Because of this, countries all over the world have taken significant steps to stop or slow down the depletion of the earth's ozone layer. Phasing out ODS is one of these measures taken by various governments. People are also encouraged to use ozone-friendly products and technology as much as possible.