Pollution is any undesirable change in physical, chemical or biological characteristics of air, land, water or soil.
Human population explosion increases the demand for food, water, home, electricity, automobiles etc. It leads to pollution. The
Government of India has passed the Environment (Protection) Act, 1986 to control environmental pollution and protect and
improve the quality of our environment.
AIR POLLUTION AND ITS CONTROL
Causes of air pollution: - It can remove over 99% particulate matter present in the
▪ Particulate & gaseous air pollutants from smokestacks of exhaust from a thermal power plant.
thermal power plants, smelters etc. - The electrons released from electrode wires (at several
According to Central Pollution Control Board (CPCB), thousand volts) attach to dust particles giving a negative
particulate size of less than 2.5µm in diameter (PM 2.5) charge. The collecting plates attract charged dust particles.
causes greatest harm to humanhealth. - The velocity of air between the plates must be low enough
▪ Pollutants from automobiles. to allow the dust to fall.
Harmful effects of airpollution: - A scrubber removes gases like SO2. In this, the exhaust is
passed through a spray of water orlime.
▪ Particulates cause respiratory problems, irritation,
inflammations & damage to lungs and premature deaths. - Very small particulates are not removed by this precipitator.
▪ Reduction in growth and yield of crops and premature Noise pollution
ENVIRONMENTAL ISSUES
death of plants. Noise is undesired high level of sound. In India, the Air
(Prevention & Control of Pollution) Act (1981) was
Control of air pollution:
▪ Separate/filter out particulate matters before releasing the
amended in 1987 to include noise as an air pollutant.
harmless gases into the atmosphere. Sources of noise pollution:
▪ Use of lead-free petrol or diesel. Music instruments, loudspeaker, crackers, industriesetc.
▪ Use of catalytic converters. Harmful effects of noise:
▪ Phasing out of old vehicles. ▪ Noise causes psychological and physiological disorders.
▪ Use of low-sulphur petrol and diesel. ▪ The sound level above 150 dB (generated by takeoff of a
▪ Application of pollution-level norms for vehicles, etc. jet plane or rocket) may damage ear drums.
▪ Use of compressednatural gas (CNG). It is used in Delhi,
▪ Chronic exposure to relatively lower noise may damage
in public transport (buses). hearing abilities of humans.
Advantages of CNG: ▪ Sleeplessness, increased heartbeat & breathing, stress etc.
o It is better and cheaper than petrol & diesel. It burns almost
Control of noise pollution:
completely.
▪ Use of sound absorbent materials in industries.
o It cannot be siphoned off by thieves and adulterated.
▪ Delimitation of horn-free zones around hospitals & schools.
Main problem of CNG: Difficulty of laying down pipelines ▪ Permissible sound-levels of crackers and loudspeakers.
to deliver CNG through distribution points/pumps. ▪ Delimit the timings of using loudspeakers.
Catalytic converter: It is the device to reduce emission of Laws & policies in India to control vehicular pollution:
poisonous gases. It has platinum-palladium & rhodium as ▪ Auto fuel policy: To cut down vehicular pollution in
catalysts. This converts Indian cities.
Unburnt hydrocarbons → CO2 + water ▪ Euro II norms:
Carbon monoxide → CO2 - Control sulphur content at 350 ppm (parts per million) in
Nitric oxide → Nitrogen diesel and 150 ppm in petrol.
Motor vehicles having catalytic converter should use unleaded - Level of aromatic hydrocarbons is to be at 42% of the fuel.
petrol because lead in petrol inactivates the catalys t. - In future: Reduce sulphur to 50 ppm in petrol & diesel
Electrostatic precipitator: (For figure see TB page: 271) and bring down the level to35%.
- It is the device to remove particulate matter. - Upgrade vehicle engines.
WATER POLLUTION AND ITS CONTROL
Domestic Sewage and Industrial Effluents o Dissolved materials: Nutrients like nitrate, NH3,
- 0.1 % impurities make domestic sewage unfit for human phosphate, Na, Ca etc.
use. They include - Removal of dissolved materials, organic compounds and
toxic metal ions are most difficult.
o Suspended solids: Sand, silt, clay etc.
o Colloidal materials: Faecalmatter, bacteria, cloth, paper - Domestic sewage contains biodegradable organic matter. It
fibres etc. is decomposed by microorganisms.
Human population explosion increases the demand for food, water, home, electricity, automobiles etc. It leads to pollution. The
Government of India has passed the Environment (Protection) Act, 1986 to control environmental pollution and protect and
improve the quality of our environment.
AIR POLLUTION AND ITS CONTROL
Causes of air pollution: - It can remove over 99% particulate matter present in the
▪ Particulate & gaseous air pollutants from smokestacks of exhaust from a thermal power plant.
thermal power plants, smelters etc. - The electrons released from electrode wires (at several
According to Central Pollution Control Board (CPCB), thousand volts) attach to dust particles giving a negative
particulate size of less than 2.5µm in diameter (PM 2.5) charge. The collecting plates attract charged dust particles.
causes greatest harm to humanhealth. - The velocity of air between the plates must be low enough
▪ Pollutants from automobiles. to allow the dust to fall.
Harmful effects of airpollution: - A scrubber removes gases like SO2. In this, the exhaust is
passed through a spray of water orlime.
▪ Particulates cause respiratory problems, irritation,
inflammations & damage to lungs and premature deaths. - Very small particulates are not removed by this precipitator.
▪ Reduction in growth and yield of crops and premature Noise pollution
ENVIRONMENTAL ISSUES
death of plants. Noise is undesired high level of sound. In India, the Air
(Prevention & Control of Pollution) Act (1981) was
Control of air pollution:
▪ Separate/filter out particulate matters before releasing the
amended in 1987 to include noise as an air pollutant.
harmless gases into the atmosphere. Sources of noise pollution:
▪ Use of lead-free petrol or diesel. Music instruments, loudspeaker, crackers, industriesetc.
▪ Use of catalytic converters. Harmful effects of noise:
▪ Phasing out of old vehicles. ▪ Noise causes psychological and physiological disorders.
▪ Use of low-sulphur petrol and diesel. ▪ The sound level above 150 dB (generated by takeoff of a
▪ Application of pollution-level norms for vehicles, etc. jet plane or rocket) may damage ear drums.
▪ Use of compressednatural gas (CNG). It is used in Delhi,
▪ Chronic exposure to relatively lower noise may damage
in public transport (buses). hearing abilities of humans.
Advantages of CNG: ▪ Sleeplessness, increased heartbeat & breathing, stress etc.
o It is better and cheaper than petrol & diesel. It burns almost
Control of noise pollution:
completely.
▪ Use of sound absorbent materials in industries.
o It cannot be siphoned off by thieves and adulterated.
▪ Delimitation of horn-free zones around hospitals & schools.
Main problem of CNG: Difficulty of laying down pipelines ▪ Permissible sound-levels of crackers and loudspeakers.
to deliver CNG through distribution points/pumps. ▪ Delimit the timings of using loudspeakers.
Catalytic converter: It is the device to reduce emission of Laws & policies in India to control vehicular pollution:
poisonous gases. It has platinum-palladium & rhodium as ▪ Auto fuel policy: To cut down vehicular pollution in
catalysts. This converts Indian cities.
Unburnt hydrocarbons → CO2 + water ▪ Euro II norms:
Carbon monoxide → CO2 - Control sulphur content at 350 ppm (parts per million) in
Nitric oxide → Nitrogen diesel and 150 ppm in petrol.
Motor vehicles having catalytic converter should use unleaded - Level of aromatic hydrocarbons is to be at 42% of the fuel.
petrol because lead in petrol inactivates the catalys t. - In future: Reduce sulphur to 50 ppm in petrol & diesel
Electrostatic precipitator: (For figure see TB page: 271) and bring down the level to35%.
- It is the device to remove particulate matter. - Upgrade vehicle engines.
WATER POLLUTION AND ITS CONTROL
Domestic Sewage and Industrial Effluents o Dissolved materials: Nutrients like nitrate, NH3,
- 0.1 % impurities make domestic sewage unfit for human phosphate, Na, Ca etc.
use. They include - Removal of dissolved materials, organic compounds and
toxic metal ions are most difficult.
o Suspended solids: Sand, silt, clay etc.
o Colloidal materials: Faecalmatter, bacteria, cloth, paper - Domestic sewage contains biodegradable organic matter. It
fibres etc. is decomposed by microorganisms.
