Page 163 - Health, Population and Environment Education 9

Pollution is caused by different types of pollutants. Pollutants are those substances which
cause pollution. There are solid, liquid and gaseous pollutants. Solid pollutants include
dust, ash, garbage, metallic and non-metallic substances. Liquid pollutants include
insecticides, pesticides, benzene, phenol, aldehydes, acid, base, etc. Gaseous pollutants
include smoke containing harmful gases like CO , CO, CH , NO, NO , SO , CFC (Chloro
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fluoro carbon) etc.
Sources and causes of environmental pollution
Environmental pollution causes negative impacts in environment. There is qualitative
and quantitative change in various resources in environment by different types of
pollution. Actually pollution is caused by human activities and changes take place in
natural environment. Increase in global warming, volcanic eruption, earthquake, flood,
landslide, soil erosion, etc. naturally cause pollution. Similarly, deforestation, unmanaged
urbanization, industrialization, excavation, conduction of development works, war,
explosion, etc. are the human activities that increase pollution. The major sources of
pollution are described bellow:

A. Natural sources

a. Change in earth’s temperature
There is increase of unmanaged industrialization and
establishment of more industries. Industries produce
excessive amount of smoke containing harmful
gases like CO , CO, CH , NO, NO , CFC, etc. which
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increase air pollution. As a result, there is increase
of greenhouse effect and global warming. There is
continuous increase of average temperature of the
earth. Due to global warming, there is melting of
snow, increase of sea level, change in rainfall pattern, Fig: 4
change in seasons, threat of avalanches, glacial lake Smoke from industries
outburst flood (GLOF), increase of desertification, famine, etc.

b. Volcanoes
Due to excessive temperature inside the earth, the
rocks are found in molten state. The molten state
of rocks inside the earth’s crust is called magma.
Sometimes magma is discharged outside from weak
land structure. This is called as volcanic eruption.
During volcanic eruption, massive amount of ash and
dust particles as well as lava are discharged outside.
Ash and dust particles cover large distance, create
air pollution, acid rainfall, spreading of diseases, Fig: 5
etc. The lava destroys surrounding plants, animals, Volcanic eruption
harms human beings and deposits large amount of rocks. There is destruction of physical
features of land, water and land as well as water ecosystem.
GREEN Environment Population and Health Education Book-9 163