Page 199 - Chemistry ICSE Class IX

Atmospheric Pollution 187
ƒ Smoke, Flyash
ƒ Metal particulates – Lead, Zinc, Cadmium, Mercury, Arsenic, etc.
ƒ Pollen grain, Bacteria and Fungi
Most particulates of solids and liquids have particle size ranging
between 0.1 – 10 μm. These particulates cause haziness in the atmosphere.

What are the sources of air pollutants

Sources of air pollutants can be natural and manmade.

Natural sources of air pollutants
Some of the natural sources which cause air pollution are:
ƒ Volcanic eruptions. Harmful gases, such as carbon dioxide (CO ),
2
carbon monoxide (CO), sulphur dioxide (SO ), hydrogen sulphide
2
(H S), hydrogen chloride (HCl), chlorine (Cl ), hydrocarbons and
2
2
particulates, are released into the atmosphere during volcanic
eruptions. Volcanic eruptions
ƒ (QTGUV ſTGU Mainly smoke, carbon monoxide (CO), carbon dioxide
(CO ) are released into the atmosphere.
2
ƒ Fog. Reduces visibility, fog when combines with smoke produces
smog.
ƒ Wind and dust storms. Carry particulate matter, such as ne sand
and dust.
ƒ Pollen and decaying biomass. Biomass on decay produces methane
gas. Methane causes pollution. Pollen grains also cause air pollution
due to release of particulate matter.

Manmade sources of air pollutants
Some of the manmade sources of air pollutants are:

ƒ Burning of fossil fuels. Coal, petrol, diesel, natural gas, LPG, kerosene
are fossil fuels. Burning of fossil fuels produce carbon monoxide (CO),
carbon dioxide (CO ), oxides of nitrogen (NO ), oxides of sulphur
2
x
(SO , SO ) and smoke. Sulphur dioxide affects skin, lungs and other
2
3
tissues. Petroleum-based fuels also release lead oxides and nitrogen
oxides into the atmosphere. Thermal power stations based on coal
produce a large quantity of y ash, carbon dioxide and oxides of
sulphur and nitrogen.
ƒ Extraction of metals. During the extraction of metals from their ores,
gases like carbon dioxide and oxides of sulphur are released. Metallic
particles produced during metallurgical operations cause severe air
pollution. These can cause permanent damage in human beings.

ƒ Heavy industries. Heavy industries, such as steel plants, cement
plants, petroleum re neries, most chemical industries, thermal power
plants, mining of minerals etc., produce harmful gases and particulates
to cause air pollution.

ƒ 7UGU QH EJNQTQƀWQTQECTDQPU Ozone layer protects the living Forest fires
organisms on the earth from the harmful ultraviolet rays coming from
the sun. Chloro uorocarbons destroy ozone. Depletion of ozone may
cause diseases like skin cancer to human and animals.