(a) The source of Sulphur dioxide in the air is the fossil fuels combustion in the power plants and other industries. It can also be produced by the motor vehicles emissions.

Sulphur dioxide is a very harmful pollutant when present in the atmosphere. It can cause the respiratory problems, including permanent lung damage.

(b) The source of nitrogen dioxide in the air is produced by the motor vehicles.

Nitrogen dioxide is a very harmful pollutant because it combines with other air pollutants and fog to form smog. The smog is responsible for causing breathing difficulties such as asthma, cough and wheezing in children.

(c) The source of carbon monoxide in the air is by the incomplete burning of fuels such as petrol and diesel.

Carbon monoxide is a very poisonous gas which reduces the oxygen carrying capacity of blood.

(d) The Chlorofluorocarbons are used in the refrigerators, air conditioners and aerosol sprays.

The Chlorofluorocarbons are responsible to deplete the ozone layer in the atmosphere. Ozone layer protects us from harmful ultraviolet rays of the sun. This results in increase of ultraviolet radiations at ground level which gives rise to an increased risk of skin cancer.