Pollution occurs when harmful substances called pollutants are released into the environment such as land, air, and water. Land pollution happens when waste is not properly disposed of and can pile up and cause disease. Water pollution occurs when bacteria and chemicals from sources like factories, farms, and garbage contaminate water bodies and kill aquatic organisms. Air pollution is caused by emissions from vehicles, factories, and the burning of fuels which produces smog and acid rain and damages buildings and ecosystems. Certain chemicals like CFCs also deplete the ozone layer allowing more UV radiation to reach the Earth.

1. • Pollution occurs when
harmful substances
called pollutants are
released into the
environment, such as
land, air and water.
Pollution
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2. • Land pollution occurs when we do not dispose of wastes
and garbage properly.
• This is caused by littering or using too many materials or
products that cannot be broken down easily by
decomposers.
• Such waste take up space and can pile up and catch fire.
• The waste also gives off a bad smell when it breaks down.
Land pollution
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3. Products made of materials that can be broken down easily
creates a more positive impact on the environment. Why?
Think about it…
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4. • Bacteria and other harmful
substances multiply very quickly in
waste and can cause diseases.
• When these organisms get into water
bodies, they contaminate the water
that is used for drinking or Man’s
other activities.
• Pesticides or fertilisers used by
farmers also contaminate the water
when they are washed into rivers
and lakes.
• They can kill the organisms living in
the polluted water.
Water pollution
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5. • Chemical waste that are discharged by factories into water
bodies also pollutes the water.
• When the chemicals get into the bodies of the organisms
living in the water, the organisms can be poisoned or even
die.
Water pollution
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6. Think about it…
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Accidents between oil tankers can cause oil spills in
the sea. What impact on the environment do these
accidents cause?

7. • We have learnt that the burning
of trees produces smoke and
causes haze and increased
carbon dioxide levels.
• Burning of fuels such as petrol,
coal and wood also produces
smoke.
• Vehicles contribute to air
pollution when they burn fuels in
order to work.
• The quality of air in places
where there are more vehicles
on the road is poorer.
Air pollution
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8. • Factories also produce smoke and harmful gases when they
burn fuels.
• When such factories do not install filters in their chimneys,
harmful gases are released into the air.
• These gases can dissolve in rainwater.
• When such water evaporates and then condenses to form
clouds, it falls as acid rain.
Air pollution
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9. Acid rain
• It can damage buildings and structures.
• It can contaminate the water in the rivers, lakes and seas.
• It can kill organisms living on land and in the water.
Air pollution
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10. CFCs
• The Earth is surrounded by a layer of ozone that protects us
from most of the harmful ultraviolet (UV) rays from the Sun.
• Chemical substances such as CFCs (chlorofluorocarbons)
used to be found in spray cans and refrigerators.
• These substances were found to destroy the ozone layer
and cause it to become thinner.
• This results in more UV rays reaching the Earth more easily.
• This can kill plants and also cause sunburns, eye
problems and skin cancer.
Air pollution
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