Pollution is any undesirable change in the physical, chemical, or biological characteristics of air, land, water, or soil. The human population explosion increases the demand for food, water, homes, electricity, automobiles, etc., leading 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
- Particulate and gaseous air pollutants from smokestacks of thermal power plants, smelters, etc.
- According to the Central Pollution Control Board (CPCB), particulate matter with a diameter less than 2.5μm (PM 2.5) causes the greatest harm to human health.
- Pollutants from automobiles.
Harmful Effects of Air Pollution
- Particulates cause respiratory problems, irritation, inflammation, damage to lungs, and premature deaths.
- Reduction in growth and yield of crops and premature death of plants.
Control of Air Pollution
- Separate or filter out particulate matter before releasing harmless gases into the atmosphere.
- Use of lead-free petrol or diesel.
- Use of catalytic converters.
- Phasing out of old vehicles.
- Use of low-sulphur petrol and diesel.
- Application of pollution-level norms for vehicles.
- Use of compressed natural gas (CNG), which is used in Delhi for public transport (buses).
- Advantages of CNG:
- It is better and cheaper than petrol and diesel, and it burns almost completely.
- It cannot be siphoned off by thieves or adulterated.
- Main Problem of CNG:
- Difficulty of laying down pipelines to deliver CNG through distribution points/pumps.
Catalytic Converter
A device to reduce emissions of poisonous gases, using platinum-palladium and rhodium as catalysts. It converts:
- Unburnt hydrocarbons → CO2 + water
- Carbon monoxide → CO2
- Nitric oxide → Nitrogen
Motor vehicles with catalytic converters should use unleaded petrol because lead in petrol inactivates the catalyst.
Electrostatic Precipitator
A device to remove particulate matter, capable of removing over 99% of particulate matter present in the exhaust from a thermal power plant.
- Electrons released from electrode wires (at several thousand volts) attach to dust particles, giving them a negative charge.
- Collecting plates attract charged dust particles.
- The velocity of air between the plates must be low enough to allow the dust to fall.
A scrubber removes gases like SO2. The exhaust is passed through a spray of water or lime. Very small particulates are not removed by this precipitator.
Noise Pollution
Noise is an undesired high level of sound. In India, the Air (Prevention & Control of Pollution) Act (1981) was amended in 1987 to include noise as an air pollutant.
Sources of Noise Pollution
- Music instruments, loudspeakers, crackers, industries, etc.
Harmful Effects of Noise Pollution
- Noise causes psychological and physiological disorders.
- Sound levels above 150 dB (e.g., generated by the takeoff of a jet plane or rocket) may damage eardrums.
- Chronic exposure to relatively lower noise may damage hearing abilities.
- Sleeplessness, increased heartbeat, breathing difficulties, stress, etc.
Control of Noise Pollution
- Use of sound-absorbent materials in industries.
- Delimitation of horn-free zones around hospitals and schools.
- Permissible sound levels for crackers and loudspeakers.
- Delimiting the timings of using loudspeakers.
Laws and Policies in India to Control Vehicular Pollution
- Auto Fuel Policy: To cut down vehicular pollution in Indian cities.
- Euro III Norms:
- Control sulphur content at 350 ppm in diesel and 150 ppm in petrol.
- Level of aromatic hydrocarbons to be at 42% of the fuel.
- Future goals: Reduce sulphur to 50 ppm in petrol and diesel and bring aromatic hydrocarbons to 35%.
- Upgrade vehicle engines.