Page 200 - Chemistry ICSE Class IX

188 ICSE Chemistry – 9

Table 8.2 Major sources and harmful effects of the air pollutants
Air pollutant Major sources Harmful effects
Gaseous Air Pollutants
1. Carbon monoxide (CO) Incomplete combustion of fossil fuels, Lowers the uptake of oxygen by
such as petrol, diesel, and coal haemoglobin, causes de ciency of
oxygen in the blood resulting in
suffocation and even death
2. Carbon dioxide (CO )* Burning of fossil fuels, volcanic eruptions Increase in the greenhouse effect, rise
2
in atmospheric temperature, melting of
polar ice
3. Oxides of nitrogen (NO ) Auto exhausts produced due to the Causes respiratory diseases, produces
x
(NO, NO )** combustion of petro-fuels in automobiles smog
2
at higher temperatures
4. Sulphur dioxide (SO ) Burning of coal, Petroleum re ning Causes headache, vomiting and lung
2
Sulphur trioxide (SO ) Metallurgical processes, Volcanic diseases, produces acid rain and
3
Eruptions promotes corrosion, forms smog
5. Hydrogen sulphide Decaying organic matter, Sewage Causes nausea, irritation in eyes and
of many chemical industries and throat, destroys vegetable matter
laboratories.
6. Ozone (O ) (at ground level) Silent electrical discharge, Arc welding Itching, burning and watering of eyes,
3
lowers our resistance to cold and
pneumonia
7. Chloro uorocarbons (CFCs) Air conditioners, Refrigerators, Aerosols Depletion of ozone layer
Particulate Air Pollutants

8. Suspended particulate Smoke, Dust, Aerosols, Fly ash from Causes poor visibility especially during
matter (SPM) coal-based thermal power stations winter, leads to dif culty in breathing,
may cause respiratory and lung diseases
Lead Leaded petrol, Lead-acid batteries, Damages the nervous system, may also
Paints cause cancer
Silica Mining, Stone-crushing, Construction Causes silicosis
Industry
Asbestos bre Asbestos mining, Manufacturing of Causes a disease called asbestosis, and
asbestos sheets, Fire proof fabric, etc. lung cancer
Mercury Fungicides Causes weakness of muscles and affects
hearing and eye sight, causes mental
retardation resulting in paralysis and
disease called minamata in human
beings
* Carbon dioxide is not a basic pollutant of air. It only causes a rise in temperature of the earth due to its greenhouse effect.
** Oxides of nitrogen are commonly expressed by the formula NO . NO stands for a mixture consisting of Nitric oxide (NO) and Nitrogen dioxide
x
x
(NO ).
2
ASSIGNMENT 2
The atmosphere, Composition of air, Atmospheric pollution, Air pollutants—their sources and harmful effects
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