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SAI International School
Subject - Chemistry
Class - VIII
Topic – Pollution of Air and water
Sub-topic-Effects of air pollution
LESSON NOTES

Effects of Air Pollution
Air pollution produces a large number of bad effects on living and non-living things. Air
pollution can cause health problems in human beings. It can kill animals and plants. It
can also damage the environment and property. Let us discuss in detail the harmful
effects of various air pollutants.

1. Sulphur dioxide
It is produced by the burning of coal in factories and thermal power plants. It is also
produced by the burning of petrol and diesel in motor vehicles. Sulphur dioxide gas in
the polluted air causes respiratory problems. It may even cause permanent lung
damage. Sulphur dioxide gas in polluted air produces acid rain. It also contributes to
the formation of smog.
2. Nitrogen oxides
It is produced by the burning of fuels like petrol and diesel in motor vehicles. They are
also produced by the burning of coal in factories and thermal power plants. Oil
refineries also produce and emit nitrogen oxides into the air. It attacks the breathing
system and leads to lung congestion. Like sulphur dioxide, nitrogen oxides present in
polluted air produces acid rain. It also contributes to the formation of smog.
Smog is a deadly air pollutant which is formed by the combination of smoke and fog.
The carbon particles, nitrogen oxides and sulphur dioxide, etc., of smoke, combines
with the condensed water vapour called fog to form smog. It causes cough and
aggravates asthma and other lung diseases, especially in children.
3. Carbon monoxide
It is produced by the incomplete combustion of fuels like wood, coal, kerosene, petrol
and diesel in homes, factories and motor vehicles. It is a poisonous gas. When
inhaled, carbon monoxide combines with haemoglobin of our blood and reduces the
oxygen-carrying capacity of our blood. This lack of oxygen causes respiratory
problems. It causes suffocation. And if inhaled too much can cause death.
4. Carbon dioxide
It is produced in excessive amount by the burning of large quantities of fuels such as
wood, coal, kerosene, petrol, diesel, and less amount in LPG, and CNG in homes,
factories and motor vehicles. Though carbon dioxide is a normal constituent of air an
excess of carbon dioxide in the air is considered a pollutant. It is the main
greenhouse gas which traps the sun’s heat in the earth’s atmosphere by producing
the greenhouse effect which leads to global warming.
5. Chlorofluorocarbons
These are the chemical compound made of chlorine, fluorine and carbon elements.
They are commonly known as CFCs. These gases are used in refrigeration, air
conditioning and aerosol sprays. CFCs are depleting the useful ozone layer of the
upper atmosphere. The ozone layer is important as it prevents the harmful ultraviolet
rays of the sun from reaching the earth surface.

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