Question

How can atmospheric pollution be caused by natural processes as well as by man-made activities?

Answer 1

On the basis of their origin (sources), pollutants are of two types: natural and man-made.

Natural sources of air pollutants

• Volcanoes: Volcanoes release large amounts of air pollutants such as carbon monoxide, Sulphur dioxide, hydrogen sulphide, chlorine, hydrogen chloride, hydrocarbons and particulates.
• Decaying vegetation: Microbial action on organic matter in soil releases a pollutant nitrous oxide.
• Forest fires release the poisonous gas monoxide.
• Winds and dust storms carry particulate matter like sand and dust.

Man-made sources of air pollutants

• Automobiles use diesel or petrol as fuel. Incomplete combustion of these fuels releases carbon monoxide, sulphur dioxide, hydrocarbons, nitrogen oxides, and particulates like lead.
• Factories release carbon dioxide, Sulphur dioxide, nitrogen monoxide, and particulates.
• Industrial processes release different types of air pollutants, depending upon the type of process involved.
• Examples: Coal power plants release carbon monoxide, sulphur dioxide, ash, and smoke. Fertilizer industries release nitrogen oxides and ammonia.
• Decay of crop residue in rural areas is the main source of carbon monoxide and methane.
• Burning of plastics releases carbon monoxide and other harmful gases.