When coal and petroleum products are burned carbon dioxide, water, sulphur dioxide and nitrogen oxides are produced as the products of combustion. Carbon monoxide is produced if combustion takes place in an insufficient supply of air.

These products affect our health and also pollute the environment in the following ways-

(i) Sulphur dioxide produces acid rain which destroys the crops and monuments. It also attacks the lungs and causes bronchitis and other diseases.

(ii) Nitrogen oxides harms us just as sulphur dioxide does. It also attacks the breathing system and causes acid rain.

(iii) Carbon dioxide is leading pollutant and cause of global warming. It traps the sun's heat energy falling on the earth consequently increasing the temperature.

(iv) Carbon monoxide gas is lethal and if it gets into our blood stream, it ceases the red blood cells from performing their function of carrying oxygen from lungs to the rest of the body causing suffocation and ultimately death.