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Environmental Issues

Air Pollution & Global Warming

Pollution is the undesirable change brought about by chemical, particulate matter, or biological materials to air, water, or soil.

Air Pollution

  • Air is a complex, dynamic natural entity, which is essential for supporting life on earth.

  • Air pollutant is a substance that causes harm to the humans and other living organisms.

  • Some of the common pollutants of air:

    • Nitrogen dioxide

    • Sulphur dioxide

    • Carbon monoxide and carbon dioxide

    • Volatile organic compounds

    • Particulate matter

Control of Air Pollution

  • Air pollution causes severe respiratory disorders in humans and other animals and also affects plants. It can be controlled by the following ways:

    • Fitting smokestacks and smelters, with filters to separate pollutants from the harmless gases

    • Particulate matter can be removed by using an electrostatic precipitator. It contains electrode wires maintained at several thousand volts, which produce electrons. These electrons cling on to dust particles and give them a net negative charge and are attracted by collecting plates, which are grounded. The velocity of air passing through the plates should be low enough to allow the dust to fall.

    • A scrubber can be used to remove gases such as SO2 wherein the exhaust passes through a spray of water or lime.

    • Vehicular pollution can be reduced by using less polluting fuels such as CNG, which is more efficient and less costly as compared to petrol or diesel. In 2002, all the buses were switched to CNG in Delhi and this has indeed led to a fall in pollution levels in the city.

    • Vehicles can be fitted with catalytic converters that have metals such as platinum, palladium, and rhodium as catalysts. These catalysts carry out the following conversions:

Unburnt hydrocarbons → CO2 and H2O

Carbon monoxide → Carbon dioxide

Nitric oxide → Nitrogen gas

Unleaded petrol must be used with catalytic converters as presence of lead in the petrol inactivates the catalyst.

Greenhouse Effect
  • It is a natural phenomenon that keeps the earth’s atmosphere warm.

    • Without this phenomenon, the temperat…

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