This video lecture from Environmental Chemistry (F.Sc. second year Chemistry) covers ozone gas and the depletion of ozone layer. Ozone is an allotropic form of oxygen, measured in DUs. It causes global warming and various health problems. It is also beneficial since it blocks the UV radiations coming towards the earth and also destroys some pollutants. Chlorofluorocarbons CFCs and several aerosol sprays create a chain reaction whereby ozone layer is depleted by a series of reactions involving free radicals. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.