Ozone is a form of oxygen. It is formed by three atoms of oxygen (Os), whereas normal oxygen molecule is diatomic (02). Oxygen is essential for all aerobic forms of life and for combustion activities. Ozone, is a deadly poison. Very little of it is present in lower part of the atmosphere called troposphere. In the stratosphere, ozone layer comprises high concentration of ozone some 18-26 km above. Ozone performs an essential function. It shields the surface of the earth from the harmful ultraviolet (UV) radiation of the sun.