Two causes of depletion of ozone layer are :
(i) Use of CFCs (Chlorofluorocarbons) in refrigeration.
(ii) Use of CFCs in fire extinguishers and aerosol sprayers.
The harmful effects of depletion of ozone layer are :
(i) Due to depletion of ozone layer, UV radiation reaches the earth. These UV radiation causes skin cancer, damage to eyes and immune system.
(ii) This depletion of ozone layer may also lead to variations in global rainfall, ecological disturbances and dwindling of global food supplies.