2. The presence of unusually high concentrations of
harmful or poisonous substances in the environment is
called POLLUTION. Pollution contaminates the air and
water with poisonous substances and makes them
impure to such an extent that they become harmful to
the human beings, other animals, plants as well as to the
non-living things. Pollution are of three types.
2
4. Air is mixture of gases. The two main gases present in air
are Nitrogen & Oxygen. Nitrogen makes up to 78% of the
air whereas oxygen makes 21% of the air and the
remaining 01% is occupied by co22, water vapor, argon
and other gases. In addition to the normal constituents
polluted air may also contain some harmful gases such
as carbon monoxide, sulphur dioxide, nitrogen oxides,
dust, smoke, etc.
4
6. The air over large cities is contaminated with harmful gases like
sulphur dioxide, nitrogen oxides, carbon monoxides, smoke &
dust etc. The contamination of air with harmful gases, smoke
and dust etc is called as Air Pollution .
The substance whose presence in the air makes it impure or
contaminated is called an Air Pollutant.
The major pollutants which causes air pollution are sulphur
dioxide, nitrogen oxides , carbon monoxides, excess of carbon
dioxide, chlorofluorocarbons, and suspended particles.
AIR POLLUTION
6
7. How WHY
A cloud of smoke
from the exhaust of
a vehicle
Increasing traffic
Smoke from a
factory chimney
Growing cities
Eruption of a
volcano
Rapid economic
development
Cigarette smoke Industrialization
Burning leaves Apathetic people
7
9. Health problems
Damage to the environment
Damage to property
Thinning of the protective ozone layer of the atmosphere
which is leading to climate changes.
HEALTH PROBLEMS
THINNING OF
OZONE LAYER
9
10. The poisonous gases like sulphur dioxide and nitrogen oxide that is released
by the industries, by burning fossil fuels, by the vehicles, etc go to the
atmosphere and pollute it. The sulphur dioxide reacts with the water vapour
to form sulphuric acid and the nitrogen oxide reacts with the water vapour to
form nitric acid. These acids get dissolved with the rain water and fall to earth
in the form of acid rain.
10
16. The TAJ MAHAL at AGRA (near Delhi) is a beautiful historical
monument made of pure, white marble. The experts have warned
that the air pollution around Taj mahal area is discoloring its white
marble and also corroding it slowly. This poses a threat to the beauty
of Taj Mahal. The acids present in the rain reacts with the white
marble and corrode it slowly.
THE TAJ MAHAL IS IN GOOD
STATE UNAFFECTED BY THE
ACID RAIN.
16
18. Carbon dioxide gas present in the atmosphere allows the heat
rays of the sun to pass through it and reach the earth but
prevents the heat rays reflected from earth’s surface and its
objects from passing out of the atmosphere into space. In this
way, the heat rays remain trapped in the earth’s atmosphere and
warm it up. The warming up of the earth’s atmosphere due to the
trapping of the heat rays by carbon dioxide gas in the
atmosphere, is called Green House Effect.
18
19. The air pollution can be controlled by using smokeless
fuels like LPG, PNG (Piped Natural Gas).
Solar water heaters should be installed to obtain hot water.
The air pollution from motor vehicles can be reduced by
using CNG (Compressed Natural Gas).
The air pollution from factories, industries, thermal power
stations, oil refineries, etc can be controlled by washing their
smoke and waste gases with jets of water.
The air pollution can be controlled by using non-polluting
sources of energy like solar energy, wind energy and hydro
energy for generating electricity.
19
21. We should not burn dry leaves, papers and garbage in the open.
We should save electricity.
We should grow more trees.
We should use utilize the plastic waste materials in making useful
materials.
We should use bicycle for covering short distances.
We should use 4R’s.
REUSE REDUCE
RECYCLERECOVER
21
22. OUCH ! WHAT HAPPENED TO MY
HOME
IT IS DAMAGED DUE
TO WATER POLLLUTION
22
23. Most of the water we use comes from the rivers and the lakes. Everyday
many unwanted and harmful substances are thrown ( or discharged ) into
the rivers or lakes. This makes the water of the rivers and lakes impure.
And we say that the water has been polluted. The contaminated of water of
rivers, lakes and ponds, etc., with the unwanted and harmful substances is
called water pollution. Water is said to be polluted when it becomes unfit
for drinking or bathing. The unwanted and harmful substances which
makes the water impure are called water pollutants. In other words, the
substances which pollute water are called water pollutants. Pollutants
make the water impure. The major pollutants which cause water pollution
are : sewage, fertilizers, pesticides, and industrial wastes. All these water
pollutants are harmful and dangerous to human beings, animals and
plants. Some pollutants can even cause death. Hot water from power plants
and industries is also considered a pollutant. This is because when very hot
water coming from power plants and industries is discharged into a river
or lake, it raises the temperature of the river water. The rise in the
temperature of the river water has an adverse effect on the animals and
plants living in it. 23
24. Toxic substances
dissolve in water or
gets deposited on the
bed.
Toxic substances
enter lakes, rivers,
streams, etc.
Pollutants go down
into the ground.
24
City sewage
Industrial waste
Agricultural run-off
25. Q.01. Which of the following is not a greenhouse gas ?
(a) Carbon Dioxide (b) Nitrogen
(c) Nitrous oxide (d) Methane
Q.02. Drinking water can be made absolutely safe by adding some
(a) Aspirin tablets (b) Iodine tablets
(c) Chlorine tablets (d) Chlorophyll tablets
Q.03. Which one of the following does not contribute in
producing acid rain ?
(a) Nitrogen Dioxide (b) Nitrogen Monoxide
(c) Carbon Monoxide (d) Sulphur Dioxide
25
26. Q.04 The constituent of polluted air which contributes in
acid rain is :
(a)Nitrogen (b) Sulphur Dioxide
(c) oxygen (d) argon
Q.05. The excessive use of one of the following can cause
the death of fish in a pond by oxygen starvation. This one
is:
(a) Fertilizers (b) Manures
(c) Pesticides (d) Herbicides
26
