Noise Pollution: Causes and effects,
Noise pollution leads to various disorders in human beings. It causes mental disorders like insomnia, anxiety, depression and behavioural and emotional stress. Moreover, deafness, hypertension, increase in sweating, dizziness, headache, nausea, vomiting, giddiness, abortion, fatigue, undesirable changes in respiration, circulation of blood in skin, dilation of pupil of eyes, constriction of blood vessels, changes in muscle tension, fright, increase in heartbeat, alterations in gastrointestinal motility and glandular reactions are the other disorders caused by noise pollution in human beings.
Most Dangerous Pollution of Man’s Environment
-Dr. Arvind Singh
Noise has become a permanent part of our lives these days because of the development of industry and technology. Unlike all other pollution causing components of environment, noise is not an element, compound or substance which can accumulate and harm future generation. It is a special kind of wave action usually transmitted by air in form of pressure waves and received by hearing apparatus present in the human body. The word noise is defined as “wrong sound, in the wrong place at wrong time”.
Therefore noise is unpleasant sound that causes irritation or annoyance. Noise pollution may be defined as introduction of undesirable sound energy into the environment at levels that can be detrimental to human activity. Noise may not seem as harmful as the contamination of air or water, but it is a pollution problem that affects human health and can contribute to a general deterioration of environmental quality. Noise pollution is the most dangerous pollution of man’s environment which is harmful to body and mind.
Unit for measurement of noise:
Loudness is the strength of sensation of sound perceived by the individual. Measurement of loudness has been devised on a logarithmic scale with reference of ten. It is called decibel (deci = 10 and bel after a name of scientist A Graham Bell). Decibel or dB is actually a ratio of loudness with reference to the softest audible sound. Audible sound is about 10 dB. The loudest sound a person can stand without much discomfort is about 80 dB. Sound beyond 80 dB is considered as pollutant as it is harmful to the hearing system. World Health Organization (WHO) has fixed sound of 45 dB as the safe noise level for a city.
Fast moving jets create pressure waves that hit objects on ground and cause rattling of window pans. These sound waves are known as sonic booms. Such booms are expressed in mach unit.
Sources of noise pollution:
Industrial revolution has substantially contributed to noise pollution in the urban areas. There are several sources of noise pollution that contribute to both indoor and outdoor noise pollution. Noise pollution is caused by vehicles, loudspeakers, electric generators, television, transistor, telephone, bands, sirens, vacuum cleaner, washing machines, food mixers, pressure cookers, fans, air conditioners, coolers, crackers and different types of machines. Mining operations, use of bulldozers, dynamites to break rocks and drillers are other important source of noise pollution. There are three kinds of noise (i) intermittent noise or non-uniform noise (ii) continuous or uniform noise; and (iii) instantaneous or impulsive noise which include the noise caused by explosions, gun shots, thunder etc. The first two are quite annoying and fatiguing causing serious health hazards.
Noise has been a source of discontent ever since people began living together in communities. In the Greek city of Sybarels in about 700BC the authorities required that potters and tin-smiths should carry out their business outside the city wall because of the noise they made. In 1713 Ramazini, the father of occupational medicine described in “De Morbis Artificum” how those engaged in hammering copper became hard of hearing and if they grew old at this work, completely deaf. The industrial revolution in the 18th century brought noise pollution. Later in 19th century industrial deafness from impact noise became more common and was known as Boilermakers disease.
Effects of noise pollution on human health:
Noise pollution has several ill effects on human beings. The most direct harmful effect of excessive noise is physical damage to the ear and the temporary or permanent hearing loss often called as 'temporary threshold shift' (TTS). Person suffering from the condition is unable to detect weak sounds. However, hearing ability is usually recovered within a month of exposure. Permanent loss usually called 'noise-induced permanent threshold shift' (NIPT's) represents a loss of hearing ability from which there is no recovery. The sound of 100 dB leads to permanent loss of hearing. Noise of about 90 dB causes auditory fatigue.
Noise pollution interferes with speech communications and reduces the working efficiency. Communication problems can lead to lack of self-confidence, irritation, fatigue and trouble concentrating. Noise is directly correlated with a decrease in helping behaviours and increase in aggressiveness.
Noise causes mental disorders like insomnia, anxiety, depression and behavioural and emotional stress. Lack of concentration and mental fatigue are significant health effects of noise. It has been observed that the performance of school children is poor in comprehension tasks when schools are situated in busy areas of a city or suffer from noise pollution. There has been report of low weight children born to mothers living near airports.
Noise pollution increases human error and decreases motivation. Difficulty in paying attention, dulling of problem solving skills and negative impact on memory are the problems caused by noise pollution.
Other disorders caused by noise pollution include hypertension, increase in sweating, dizziness, headache, nausea, vomiting, giddiness and fatigue. Furthermore, undesirable changes in respiration, circulation of blood in skin, dilation of pupil of eyes, constriction of blood vessels, changes in muscle tension, fright and increase in heart beat and alterations in gastrointestinal motility and glandular reactions are the other physiological disorders caused by noise pollution in human beings. Noise pollution may even cause damage to brain and liver.
Noise pollution also increases the risk of peptic ulcer in human beings. Continuous exposure to noise may lead to abortion in the pregnant women. Noise also causes an increase in cholesterol level, which blocks the coronary arteries thus making the person prone to heart attack and strokes. At higher impulsive noise pollution the pulse rate and blood pressure changes, stored glucose from the liver is released into the blood stream and there is an increased production of hormone adrenalin. The brain begins to exhibit distorted electroencephalographic brain wave records.
Noise of around 125 dB causes visual disturbance, and reduces the depth and quality of sleep thus affecting the overall physical and mental health.
Noise pollution have adverse effects on sexual potency and cause an increase in social conflicts.
As noise interferes with normal auditory communication it may mask auditory warming signals and hence increases the rate of accidents especially in industries. It can also lead to lowered worker efficiency and productivity and higher accident rates on the job.
Control of noise pollution:
Since noise affects the quality of human life. Therefore, it is necessary to ensure the control of noise pollution.
There are four fundamental ways in which noise can be controlled. These includes reduce noise at the source, block the path of noise, increase the path length, and protect the recipient. In general, the best control method is to reduce noise levels at the source. At the source, such as in motors, vehicles etc. use of silencer devices helps in noise mitigation. In industries noise reduction can be done by using rigid scaled enclosures around machinery lined with acoustic absorbing material. Isolating machines and their enclosures from the floor, using special spring mounts or absorbent mounts and pads, and using flexible coupling for interior pipelines can also contribute in mitigating noise pollution at source.
Noise levels at construction sites can be controlled using proper construction planning and scheduling techniques. Locating noise air-compressors and other equipment away from the site boundary along with creating temporary barriers to physically block the noise can also be helpful in mitigating noise pollution.
A smooth flow of traffic also causes less noise than does a stop-and-go traffic pattern. Proper highway planning and design are necessary for controlling traffic noise. Establishing lower speed limits for highways that pass through residential areas, limiting traffic volume, and providing alternative routes for truck traffic, are effective noise-control measures. Constructing vertical barriers alongside the highway can also block the path of traffic noise.
Making highways not in close touch with towns and cities may also check noise pollution. There should be methodological spacing of office hours of different categories i.e. school, colleges, factories and industries.
Use of acoustic absorbers in structural designs of buildings can mitigate noise pollution. Wood panelling and wood fibre wallboards have a very high coefficient of noise absorption. Special porous materials are also manufactured for panelling auditorium and theatre halls to reduce the intensity of noise.
Plants have the attribute of absorbing and dissipating sound energy. Therefore, trees can be planted along highways, streets and other places exposed to noise pollution. Plantation of trees around residential areas can also act as effective noise barriers. Potential tree species for this purpose include tamarind (Tamarindus indica), neem (Azadirachta indica), sissoo (Dalbergia sissoo), teak (Tectona grandis), pongam (Pangamia pinnata) and ashok (Polyalthia longifolia).
The person exposed to the noise can also control noise pollution through use of wearing devices like earplugs and earmuffs. Specially designed earmuffs can reduce the sound level reaching the ear drum by as much as 40 dB.
Enacting strict laws can also be helpful in controlling noise pollution. Restrictions should be put on use and volume of loudspeakers and pressure horns of vehicles. India Motor Vehicle Act, 1988, which has come into force from 1st July 1989, is already there to check noise pollution. However, viewing the present situation more strict laws are needed to control noise pollution.
Noise pollution can also be controlled by education. Therefore, public should be educated regularly through electronic and print media and also through other awareness programmes regarding the harmful consequences of noise pollution.
It can be concluded that noise pollution causes several physical, mental and physiological disorders in human beings, hence it is a serious menace to human health. Therefore, it is extremely essential to make all possible efforts to control the threat of noise pollution for sound human health in the present era of industry and technology.Dr. Arvind Singh is M. Sc. and Ph. D. in Botany with area of specialization in Ecology. He is an dedicated Researcher having more than four dozen of published Research Papers in the Journals of National and International repute. His main area of Research is Restoration of Mined Lands. However, he has also conducted Research on the Vascular Flora of Banaras Hindu University Main Campus, India.