Noise pollution

Noise has become a permanent part of our life these days because of the development of machinery, industry and technology. Noise harms the body and mind. Noise not only cause irritation or annoyance but it constricts our arteries, increases the flow of adrenaline and forces our heart to work faster. The word noise is usually defined as unwanted or unpleasant sound that causes discomfort. Noise pollution means “the unwanted sound dumped into the atmosphere leading to health hazards.”

Formerly noise was limited only to the industry. This too was much as there were only few industries. These days there has been rapid industrial growth. Moreover, there has been population explosion, due to which there is heavy traffic, urban crowd and electric equipment. All these have added to the noise in environment. In our country, besides these the two other factors are the religious and social functions which increase the gravity of situation.

Sources of noise:

The main contributors to noise are factories and industries, transportation (air, rail and road) and community and religious activities. The chief man-made sources in urban areas are automobiles, factories, industries, trains, airplanes. Noise makers are horns, sirens, lawn movers, musical instruments, TV, radio, transistor, telephone, dogs, loudspeakers, washing machines, vacuum cleaner, pressure cookers, fans, air conditioners, coolers. Ever since the industrial revolution, there has been increase of environmental noise.

Properties:

There are two basic properties of sound:

(i) Loudness and

(ii) Frequency.

Loudness is the strength of sensation of sound perceived by the individual. It is measured in terms of decibels. Just audible sound is about 10 dB, a whisper about 20 dB, library place, 30 dB, and normal conversation 35-60 dB, heavy- street traffic 60-80 B. sounds beyond 80 bB can be safely regarded as pollutant as it harms hearing system. The WHO has fixed 45 dB as the safe noise level for a city. For international standards a noise level up to 65 dB is considered tolerate.

Loudness is expressed in sones. One sone equals the loudness of 40 dB sound pressure at 1000 Hz. Frequency is defined as the number of vibrations per second. It is denoted as Hertz (Hz). One Hz equals to one vibration per second. People can hear sound from 20 (infra-audibile) to 20,000 (ultrasonic) Hz.

Effects of Noise Pollution:

The different effects are categorized as:

(i) Auditory effects (affecting hearing faculty) and

(ii) Non-auditory effects (other than auditory ones).

1. Auditory effects:

These include auditory fatigue, and deafness. Auditory fatigue appears in the 90 dB and may be associated with side effects as whishing and buzzing in ears. Deafness can be caused due to continuous noise exposure. Temporary deafness occurs at 4000-6000 Hz. Permanent loss of hearing occurs at 100 db. Mumbai and Kolkata are the nosiest cities in the world. Many persons have risk of deafness.

2. Non-auditory effects:

These are:

(i) Interference with speech communication,

(ii) Annoyance,

(iii) Loss of working efficiency and

(iv) Physiological disorders.

(a) Interference with speech communication:

A noise of 50- 60 dB commonly interferes with speech; sound of warning (signal) may be misunderstood.

(b) Annoyance:

Balanced persons express great annoyance at even low level of noise as crowd, highway, radio etc. The effects are ill temper, bickering etc.

(c) Loss in working efficiency:

There develop tiredness and those doing mental work may put to deterioration in their efficiency or even complete loss of ability to work.

(d) Physiological disorders:

There develop a number of physiological disorders due to imbalance in functioning of the body. These are neurosis, anxiety, insomnia, hypertension, hepatic diseases, behavioral and emotional stress, increase in sweating, giddiness, nausea, fatigue etc.

Noise also causes visual disturbance, and reduces depth and quality of sleep thus affecting overall mental and physical health. Other effects are undesirable changes in respiration, circulation of blood in skin and gastrointestinal activity. Noise pollution also causes incidence of peptic ulcers.

Continuous noise causes an increase in cholesterol level resulting in the construction of blood vessels making one prone to heart attack and strokes. There may be still births and usually low weight children born to mothers living near airports.

Supersonic air planes create a shock wave called sonic boom, which produces a startle effect that can be more harmful than a continuous noise. The sonic boon may spread in an area of 10 to 80 miles and when it hits the ground it damages window panes and building structures. This may also fasten the human foetus heart beat rate.

Control:

There are following ways to control and reduce the noise menace:

1. At source control:

This can be done by (i) designing and fabricating silencing devices in aircraft engines, automobiles, and industrial machine and home appliances and by segregating the noisy machines. There could be developed gadgets to control noise at source.

2. Transmission control:

This can be achieved by converting the room walls with sound absorbers as acoustic tiles and construction of enclosures around industrial machinery.

3. To protect posed person:

The workers exposed to noise can be provided with wearing devices as ear plugs and ear muffs.

4. To create vegetation cover:

Plants absorb and dissipate sound energy and thus act as buffer zone. Trees should be planted along high, ways, streets and other places. Ashok Neem, Tamarind etc. are good for this purpose.

5. Noise pollution through law:

Silence zones must be created near schools, hospitals and indiscriminate use of loudspeakers at public places may be done by laws. Adequate restrictions must be put on unnecessary use of horns and vehicles plying without silencers. There are already laws in some countries as U.K. and U.S.A.-In India; we have Motor Vehicles Act which provides restriction on trucks using double sirens while passing through some localities. But this is not enough.

There is Indian Penal Code that has some provisions to which resort can made on the ground of nuisance. These are Sections 268 and 290. Fortunately, noise has now been included under air pollution in the Air Pollution Control Act.

6. Education:

Public must be made aware and educated about noise nuisance through adequate news media, lectures and other programmes. The movement against noise pollution is very weak in India. The main reason being that most of us do not consider noise as a pollution but as a part of routine life.