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BIOLOGY
Automobiles are a major cause for atmospheric pollution atleast in
the metro cities. As the number of vehicles increase on the streets, this
problem is now shifting to the other cities too. Proper maintenance of
automobiles along with use of lead-free petrol or diesel can reduce the
pollutants they emit. Catalytic converters, having expensive metals namely
platinum-palladium and rhodium as the catalysts, are fitted into
automobiles for reducing emission of poisonous gases. As the exhaust
passes through the catalytic converter, unburnt hydrocarbons are
converted into carbon dioxide and water, and carbon monoxide and nitric
oxide are changed to carbon dioxide and nitrogen gas, respectively. Motor
vehicles equipped with catalytic converter should use unleaded petrol
because lead in the petrol inactivates the catalyst.
In India, the Air (Prevention and Control of Pollution) Act came
into force in 1981, but was amended in 1987 to include noise as an air
pollutant. Noise is undesired high level of sound. We have got used to
associating loud sounds with pleasure and entertainment not realising
that noise causes psychological and physiological disorders in humans.
The bigger the city, the bigger the function, the greater the noise!! A
brief exposure to extremely high sound level, 150 dB or more generated
by take off of a jet plane or rocket, may damage ear drums thus
permanently impairing hearing ability. Even chronic exposure to a
relatively lower noise level of cities may permanently damage hearing
abilities of humans. Noise also causes sleeplessness, increased heart
beat, altered breathing pattern, thus considerably stressing humans.
Considering the many dangerous effects of noise pollution can you
identify the unnecessary sources of noise pollution around you which
can be reduced immediately without any financial loss to anybody?
Reduction of noise in our industries can be affected by use of sound-
absorbent materials or by muffling noise. Stringent following of laws laid
down in relation to noise like delimitation of horn-free zones around
hospitals and schools, permissible sound-levels of crackers and of loud-
speakers, timings after which loudspeakers cannot be played, etc., need
to be enforced to protect ourselves from noise pollution.
16.1.1 Controlling Vehicular Air Pollution: A Case
Study of Delhi
With its very large population of vehicular traffic, Delhi leads the coun-
try in its levels of air-pollution – it has more cars than the states of
Gujarat and West Bengal put together. In the 1990s, Delhi ranked
fourth among the 41 most polluted cities of the world. Air pollution
problems in Delhi became so serious that a public interest litigation
(PIL) was filed in the Supreme Court of India. After being censured very
strongly by the Supreme Court, under its directives, the government
was asked to take, within a specified time period, appropriate meas-
ures, including switching over the entire fleet of public transport, i.e.,
buses, from diesel to compressed natural gas (CNG). All the buses of
Delhi were converted to run on CNG by the end of 2002. You may ask
the question as to why CNG is better than diesel. The answer is that