Which of the following pollutants is the major contributor to photochemical smog?

Ozone : • Ozone is an allotrope of Oxygen, with molecular formula 03. • It is stabilised by resonance i.e. delocalisation of electrons. • It is a pale blue coloured gas present in our the stratosphere layer. • It protects us from the harmful Ultraviolet Rays coming from the sun. • The chlorofluorocarbons (CFCs) are the ozone-depleting agents originating from Air Conditioners, Refrigerators and Aerosols. • Montreal Protocol was signed on September 16, 1987, for the protection of Ozone, that entered into force on January 1, 1989. • But when Ozone is present at ground level, instead of atmosphere it acts as a pollutant.