Page 205 - Science Class 08

v The decaying or organic ma er release Smoke : Smoke is mainly released by the
methane gas in the air to pollute it. burning of fossil fuels like coal, wood and

v Wind also carries pollen grains of plants petroleum products from the domes c hearths,
which affect people sensi ve to it. factories and motor vehicles. When smoke
combines with fog, smog is formed which is
Man-made Sources
very harmful for living beings. The smoke
Man-made sources of air pollu on include: released by vehicles contains nitrogen oxides,

Suspended Par culate Ma er (SPM) : Tiny hydrocarbons and carbon monoxides. It causes
solid par cles suspended in air are known as eye irrita on.
suspended par culate ma er or SPM.
Suspended par culate ma er are released

from thermal power plants in the form of ash
or unburnt carbon par cles, fine dust from the
cement factories and from the exhaust of
vehicles. These fine par cles cannot be filtered
by the hair in our noses and they reach our
lungs causing serious diseases. They also se le
on the leaves of plants causing disturbance in
photosynthesis. Pes cides : Farmers use pes cides like aldrin,
diendrin, lindane, DDT, etc. to kill the pests and
to protect their crops and fruit-trees. But,
excessive use of these pes cides also causes air
pollu on. Similarly, herbicides or weedicides
are used to kill harmful plants. These chemicals
also cause air pollu on. These chemicals,
some mes, enter our body through food items
causing skin diseases.

Dust from Cement Factory
Harmful Gases : Harmful gases which act as
major air pollutants include carbon monoxide,

sulphur oxide, hydrogen sulphide, hydrogen
fluoride, nitrogen, etc. These gases are
released from the burning of fossil fuels in
factories, thermal power plants and auto-
mobiles. Carbon monoxide combines with Chlorofluoro Carbons (CFCs) : Chlorofluoro
haemoglobin and reduces its oxygen carrying carbons are used in refrigera on, fire
capacity. Pollutant gases also cause many other
ex nguisher and aerosol sprayers. Chlorofluoro
diseases and environmental degrada on. carbons, if released in the atmosphere, deplete

Science-8 205