Ozone is an isotope of oxygen. It is formed by three atoms of oxygen . 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 ultraviolet (UV) radiation of the Sun. Synthetic chemicals such as chlorofluorocalbons (CFCs) released into the air accumulate in the upper atmosphere and react with ozone resulting in reduction of the ozone layer. Thus, ozone layer becomes thinner and gets depleted allowing more ultraviolet rays to pass through the earth's, atmosphere. This radiation is highly damaging to organisms producing skin cancer, damage to eyes including increased incidence of cataract and damage to the immune system of human beings and other animals.