), a powerfull bleaching, poisonous oxidizing agent with a pungent, irritating odor, is formed naturally from diatomic oxygen by electric discharge in air or exposure to ultraviolet radiation.
The ozone layer
in the stratosphere absorbs UV radiation that shields the Earth surface from incoming harmful UV radiations. In the troposphere the ozone is mostly a result of anthropogenic pollution and therefore higher concentrations are found in urban areas. Ozone is involved with oxides of nitrogen (NOx) in the photochemical production of many of the constituents of polluted environments. Stratospheric ozone is depleted by reactions with chlorine derived from chlorofluorocarbons (CFCs), which results in more solar UV radiation reaching the Earth's surface below ozone-depleted regions of the stratosphere.