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Tomorrow is the history exam, and you are
trying to concentrate on ‘battle of Plassey.’ But blaring loudspeakers have been
driving you distracted. All of us have sometimes wanted to plug our ears to shut out the
racket. When does music become noise? |
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| Noise is among the most pervasive
pol-lutants today.But it is an inescapable by-product of urbanisation and
indus-trialisation. Any sound that intrudes into our daily activities, is unwanted or
offensive, is noise. And road traffic, jet planes, construction work, factories and
appliances all contribute to the audible litter that we hear everyday |
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Noise
beats
A study found that if 75 normal healthy individuals are exposed for 10-15 years
to noise of 88-107 decibels for 6-8 hours each day, 18 per cent of them have irregular
cardiac rhythms. |
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Full blast
The World Health Organisation has fixed 45 decibels as the safe noise level for a
city. India also has limits set for maximum levels of noise and they vary for different
areas of a city. It is 55 decibels for residential areas, 65 decibels for commercial areas
and 75 decibels for industrial areas. For silent zones (hospitals and educational
institutions) the limit is 50. At night noise levels are supposed to be lower still and
laws state that loudspeakers cannot be used between 10 pm and 6 am. But metropolitan areas
in India usually register an average that is more than 90 decibels. Mumbai tops the charts
as the third noisiest city in the world and Delhi follows close on its heels. The Central
Pollution Control Board (CPCB) says that vehicles make most of the din in the capital.
Delhi has the highest number of two-wheelers in the world and these make the maximum noise
per passenger than any other vehicle.
Sound effects
So noise is irritating. But it isn’t really harmful is it? Well, animals change
migration routes to avoid noise and military sonar disturbs marine animals (see box). And
studies seem to suggest that loud noise levels have some serious physiological and
psychological effects on humans too.
Our ears are a finely tuned mechanism and can catch weak sounds at zero decibels in a
quiet environment. But when the volume starts rising, the ears rebel. At 120 decibels ears
register pain and sounds measuring 150 decibels can rupture the eardrum. But the damage
may start much earlier, at 90 decibels. Noise pollution may also cause irritability,
indigestion, high blood pressure and even heart disease.
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Dolphins could be dying because of noise
pollution. Noise from US navy sonar and oil exploration activities make the dolphins dive
deeper. When they dive, nitrogen is squeezed out of their lungs and bubbles into the
bloodstream. When they surface, the dolphins breathe out to get rid of the bubbles. But
noise from sonar can make the nitrogen bubbles so big that they block blood vessels and
crush nerves. |
Un-sound Laws
But the government seems unaware of the risks and noise laws were formulated very late.
The CPCB set standards for noise pollution in 1989 and the Ministry of Environment and
Forests (MOEF) formulated Noise Pollution Rules only in 2000. And these laws are flouted
regularly. For instance, MOEF banned manufacture of firecrackers that generate more noise
than 125 decibels. The firecracker industry was also asked to print noise levels on
wrappers. But none of this was implemented. Laws by themselves are obviously not enough.
So, for now, it seems that the people have to just grin and bear with the noisy din.
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