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Noise Pollution is a Major Problem for Human Health and the Environment
Noise has been well-defined as unwanted sounds, which is being dumped into the atmosphere to disturb the unwilling ears. It adversely affects our physiological and mental health. The word ‘noise’ comes from the Latin word nausea which means seasickness or I do harm. Noise pollution means some displeasing sounds, created by human or machine that disrupts the environment. Noise pollution or sound pollution is such that the exposure of people or animals to such levels of noise is annoying, stressful, or damaging to the ears.
Noise is measured in units called decibels (dB). Decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity relative to a specified or implied reference level. The founder of this decibel system and telecommunication pioneer is Sir Alexander Graham Bell.
Decibel (dB) = \(10 \log _{10}\left(\frac{x}{X_0}\right)\)
[Where X is the actual value of the quantity being measured and X0 is a specified or implied reference level.]
According to international standards, a noise level of upto 65 dB is considered a tolerable range. Sounds beyond 80 dB can be safely regarded as pollutant as it harms the hearing system. The WHO has fixed 45 dB as the safe noise level for a city. The noise quantum of some of the cities in our country indicates their pitch in decibels in the noisiest areas of corresponding cities, e.g., Delhi-80 dB, Kolkata-87 dB, Bombay-85 dB, Chennai-89 dB, etc. The intensity of some noise sources is as follows:
Sources | Intensity (dB) |
1. Soft Whisper | 20-30 |
2. Library | 30-35 |
3. Normal Conversation | 35-60 |
4. Office Noise | 60-80 |
5. Traffic | 50-90 |
6. Motor Cycle | 105 |
7. Train Whistle (over 50′) | 110 |
8. Aircraft (over 100′) | 110-120 |
9. Pneumatic Drill | 110-120 |
10. Commercial Jet | 120-140 |
Sources of Noise Pollution
Noise pollution like other pollutants is also a by-product of industrialization, urbanization, and modern civilization. Broadly, noise pollution has two categories, i.e., industrial and non-industrial noise pollution. The industrial source includes the noise from various industries and big machines working at a very high speed and high noise intensity. Non-industrial source of noise includes the noise created by transport/vehicular traffic and the neighborhood noise, which can also be divided into natural and man-made categories. Most noise-promoting sources are given here:
- Industrial Noise: Various industries, such as textile mills, printing presses, engineering establishments, etc. produce lots of unpleasant sounds.
- Agricultural Noise: Agricultural machines like tractors, shallow machines, harvesters, tubewells, etc.
- Road Traffic Noise: In the city, the main sources of traffic noise are trucks, buses, motorcycles, cars, etc.
- Aircraft Noise: This is the major problem of the airport and its surrounding areas, including the problem of low-flying military aircraft which has added a new dimension to community annoyance.
- Noise from Railroads: The noise from locomotive engines, horns and whistles, and switching and shunting operations in rail yards has an impact on neighboring communities and railroad workers.
- Construction Noise: The noise comes from the construction of highways, city streets, and buildings, including pneumatic hammers, air compressors, bulldozers, pavement breakers, etc.
- Noise from Domestic Gadgets and Entertaining Equipment: Domestic gadgets like air-conditioners, vacuum cleaners, exhaust fans, mixers, pressure cookers, etc., and entertaining equipment like public address systems e.g., loudspeakers.
Effects of Noise Pollution
The effects of noise pollution on human beings, animals, and property are as follows:
1. Effects on Hearing:
Prolonged and continued high-intensity noise not only causes some hearing loss but may cause a permanent loss of hearing. A sudden loud sound, such as an explosion, can damage the tympanic membrane. Occupational deafness is common in industries.
2. Decreases the Efficiency of a Man:
There are a number of experiments that point out the fact that human efficiency increases with noise reduction. Thus, human efficiency is related to noise.
3. Lack of Concentration and Fatigue:
Concentration is the key to any quality work. Noise causes a lack of concentration. In big cities, almost all the offices are on the main road. The noise of loudspeakers and different types of horns divert the attention of people working in offices, and then they suffer from fatigue. Noise also causes emotional disturbances.
4. Serious Physiological Disorders:
Noise causes headaches by dilating blood vessels of the brain, eye strain by dilating the pupil, digestive spasms through anxiety, and high blood pressure by increasing cholesterol levels in the blood. Noise pollution also causes an increase in the rate of heartbeat, constriction of blood vessels, decreased cardiac output, and defective night and colour vision.
5. Effects on Foetus:
Noise can impair the development of the nervous system of unborn babies which leads to abnormal behaviour in their later life. Sometimes unpleasant sudden sound causes abortion in pregnant females.
6. Effects on Vegetation:
Plants are also as sensitive as humans. Plants require a calm and peaceful environment for their better growth. Noise pollution causes poor quality of crops in an unpleasant atmosphere.
7. Effects on Animals:
Noise pollution damages the nervous system of animals. Animals lose control of their minds. They become dangerous. Birds also get affected and face problems in laying eggs.
8. Effect on Property:
Loud noise is also very dangerous to buildings, bridges, and monuments. It creates waves that strike the walls and put the construction in dangerous conditions. It weakens the edifice of buildings.
Control of Noise Pollution
The control measures for noise pollution depend upon three factors:
- to reduce the source of noise.
- Control the path of its transmission.
- to safeguard the receiver of noise or to protect exposed persons.
1. Noise Control at Sources
This can be done by employing the following techniques like
- Reducing the Noise Levels from Domestic Sectors: Radio, CD, DVD players, televisions, and cooking appliances that can be minimized by their selective and judicious operation and also using some sound absorbing materials (like carpets, jute walls, mats, etc.) in the room.
- Maintenance of Automobiles: Installing silencers, or sound-reducing apparatus to vehicles, regular servicing, and tuning of vehicles will reduce the noise levels.
- Control Over Vibrations: The vibrations of materials may be controlled by using proper foundation, rubber padding, etc.
- Low Voice Speaking: For communication low voice speaking can reduce the excess noise level.
- Prohibition of Usage of Loud Speaker: In the habitat zone usage of loudspeakers should be prohibited other than important meetings/functions/announcements.
- Maintenance of Machines: Proper lubrication and maintenance of machines, automobiles, etc. reduce the excess noise levels, and also improve the life of machines and automobiles.
2. Control in the Transmission Path
The available techniques are briefly discussed below:
- Installation of Barriers: Barriers between the source and receiver can reduce the noise levels and that can be done by various engineering methods.
- Design of Building: This can be achieved by incorporating the use of suitable noise-absorbing materials for walls, doors, windows, and ceilings which will reduce the noise levels. Typical exterior wall construction also reduces outside noise levels.
- Installing Panels or Enclosures: It is also a very effective technique for mitigating noise levels.
- Green Belt Development: It can attenuate the noise levels. Plants mainly shrubs and trees absorb and dissipate sound energy and thus act as buffer zones. Plants should be planted along the highways, streets, and other crowded areas. Those will attenuate various pollutants including noise.
3. Protection of Exposed Person
The usage of protective equipment and the workers’ exposure to the high noise level can be minimized in the following ways:
- Hearing Protection: Equipment like ear muffs, ear plugs, etc., are the commonly used devices for hearing protection.
- Job Rotation: By rotating the job between the workers working at a particular noise source or isolating a person, the adverse impacts can be reduced through this process.
- Exposure Reduction: 90 dB continuous exposure to noise level for more than 8 hours creates occupational health hazards. So schedule of the workers should be planned in such a way that they should not be overexposed to the high noise levels.
Indian Standards for Ambient Noise Levels
This is according to the Ministry of Environment and Forest (MOEF) Guideline vide Environment (Protection) Act 1986, third amendment rules. Damage risk criteria for hearing loss Occupational Safety & Health Administration (OSHA) regulations. No exposure in excess of 115 dB is permitted.
Area | Noise Limits, Leq dB | |
Day Time (6.00 hrs to 21.00 hrs IST) | Night Time (21.00 hrs to 6.00 hrs IST) | |
Silence Zone (upto 100 m around hospitals, educational institutions & courts) | 50 | 45 |
Residential Zone | 55 | 45 |
Commercial Zone | 65 | 55 |
Industrial Zone | 75 | 65 |
Source: Jeva, R. et al., Noise Impact Assessment-an approach, Energy Environment Monitor, Vol. 12, September 96.