A triatomic molecule that is formed by the three atoms of oxygen is known as ozone. It occurs in the upper part of the atmosphere called the stratosphere. It lies at the height of 11-16 km above poles and 23-25 km above the equator. It shields the surface of the earth from ultraviolet radiation, which can cause cancer and several skin diseases.

Ozone hole is the depletion of the protective ozone layer in the upper atmosphere of the Earth. It is caused due to ozone-depleting substances such as chlorofluorocarbons (CFCs), halon, carbon tetrachloride, methyl chloroform, methyl bromide, hydrobromofluorocarbons, and bromochloromethane.