In most developing countries, noise pollution is on the increase because of industrialization, increasing traffic, population and urbanization. Many city centres of urban areas are characterized with excessive noise above tolerable threshold levels.
Most of these noises emanate from products promotions, motor vehicles, sales of electronics, and the use of electric power generators due incessant power failure from public supplies. Unknown to many, this noise could have a negative health impact on the population exposed to it. In this unit we will examine noise as a factor of pollution and the effects it has on human health.
Concept of Noise Pollution
Sound is a form of energy and a sensory perception evoked by a physiological process in the auditory brain, which may be noise, music or speech, etc. noise may therefore, be defined as an unwanted/disturbing sound or the wrong sound in the wrong place at the wrong time a barking dog, loud music, passing traffic, a power plant or generator. It is a non- harmonious or discordant sound wave often harsh, discomforting and unpleasant to the ear.
Noise impacts directly on the environment, causing annoyance or illness, but can be reduced/controlled by appropriate engine, and silencers.
A quiet environment is a restful place that promotes relaxation, good health and happiness and a happier and healthier community. Noise on the other hand, is a disturbance (pollution) to the human environment by disrupting normal domestic activity like reading or watching television.
It can disturb work, concentration, relaxation and sleep, amongst other things, and causes stress, which impacts adversely on human health (EPA/VIC, 2006).
The many consequences of elevated sound levels (e.g. Population annoyance, interference with communication and impaired task performance, besides stress, induce health illnesses) constitute one of the most widespread public health threats to human population in both industrialized and developing countries.
Noise pollution is on the increase in all areas, especially in the urban areas; this is because of increase of population, urbanization and traffic levels (road, air, and rail). Besides, residential areas are encroaching into noisy industrial areas, exposing more population to hazardous noise levels.
According to WHO, governments have a responsibility for the health of their people, which can be fulfilled only by the provision of adequate health and social measures in the form of legislation to control noise generation/abatement. It is therefore, an offence to cause an unreasonable noise from any residential premises and to use some equipment in construction work during prohibited times.
Sources of Noise
Noise has been categorized into two groups: noise associated with machinery, equipment and general workplace is referred to as occupational or industrial noise. However, the majority of the population is exposed to or tormented by noise from diverse sources outside the industrial workplace, either indoors or outdoors, which is all together, called community, environmental, residential or domestic noise. This by way of definition is noise emitted from all sources, except the industrial workplace.
Residential noise is any noise from a house, apartment or flat, commonly neighbors stereos, radios and air conditioners. An unreasonable noise exists when the said item can be heard in a habitable room of a neighboring house during a prohibited time, whether or not the windows and doors are open, if it goes on for a protracted time.
Outdoor sources of noise include road (motor vehicle noise, horn abuse by drivers, exhaust and tire friction) rail and air traffic, industries, construction and public works, entertainment (Loud music from hotel club, discos and concerts), alarms and sirens, and the neighborhood.
Other sources of noise include shops, rubbish collection, public address systems. It also include pets and leisure activities like shooting, tennis playing, church bell ringing and other religious activities and fireworks.
In our case, one will not fail to add the noise from the ubiquitous power generating set as each household in the towns and villages strive to generate its electricity.
The main indoor noise sources are ventilation systems, office machines, house appliances, food blenders, sewing machines, vacuum cleaners, electric can cutters, dishwashers, etc. Thus, there is no escape from noise as modern lifestyles and transportation habits continually generate more noise, worsening the overall noise level and leading to hearing loss and ill-health.
Mechanized industries generate a serious noise problem – indoors as well as outdoors from all sorts of powerful machines that have impulsive and unpleasant disruptive temporal sound patterns.
Noise from industries affect nearby communities and be reduced by the use of quieter equipment, zoning of land into industrial and residential areas, sound insulation enclosures, active noise control measures like restriction of operation time.
Read Also: Concept and Definition of Pollution
Effects of Noise on Health
WHO observed that 120 million people have disabling hearing defects world-wide. In developed countries, 12 per cent – 15 per cent employed people are exposed to noise levels of 80db or more. Prolonged or excess exposure to noise can cause permanent medical conditions such as peptic ulcer disease, hypertension, and ischemia heart disease.
Some prominent noise effects on human health include:
Aural pain is induced when the tympanic membrane is stretched by large amplitude sound pressure and which may rapture the membrane.
At 80db physical discomfort is experienced and pain at 110 – 130db. In an inflamed ear 80 – 90db will cause pain, but no pain is felt in the ear without eardrum at 170db.
2. Hearing Impairment
Hearing impairment generally refers to the hearing level at which individuals begin to experience difficulty understanding speech. In the USA, it approximates 26db or more at 0.5, 1, and 2 kHz. In the UK it is 30db or more at 1, 2, and 3 kHz. The direct effect of noise is hearing impairment, which is defined as an increase in threshold of hearing.
Noise induced hearing impairment occurs mostly in higher frequencies of 3000 – 6000Hz. With increasing levels and exposure time, impairment occurs at frequencies as low as 2000Hz, resulting in the loss of clarity rather than loudness. At 75db or less no impairment is expected to occur.
In developing countries, both occupational and environmental noises constitute increasing risk factors for hearing impairment. Hearing loss occurs gradually, beginning with loss of occasional words in general conversation and difficulty understanding speech heard on the telephone.
The main social consequence of hearing impairment is the inability to understand speech in daily living conditions a severe and incurable social handicap resulting in difficulty participating in lectures, meetings, parties, besides listening to TV, radio and telephone.
3. Sleep Disturbance
Sleep disturbance is a major effect of environmental noise. Uninterrupted sleep is prerequisite for good physiological and mental functioning. Noise induced sleep disturbance will particularly cause difficulty in falling asleep, awakening and alterations of sleep stages or depth.
Effects of noise upon sleep depend on the characteristics of the noise stimulus, the age and the sex of the sleeper, history of previous sleep adaptation and motivation. Noise inhibits increase in eosinophil’s and basophiles that occur during sleep.
The sleep of children and younger people are less affected than that of the middle age and older people. Women are more sensitive to noise than men during sleep.
Noise causes increased blood pressures, heart rate and higher pulse amplitude, vascular constriction, changes in respiration, cardiac arrhythmias and increase body movement during sleep. The probability of being awakened increases with the number of noise event per night. For a good night sleep, equivalent sound level should not exceed 30db.
4. Stress Response
Noise, especially sudden and unexpected, evokes primitive stress response the flight or flight reaction of the autonomic nerve system. If the noise stimulus is sustained, it will cause persistent changes in the neurosensory, circulatory, endocrine, and secretory and digestive systems.
Noise exposure affects the body‘s physiological function both temporarily and permanently. After prolonged exposure to noise, susceptible individuals develop hypertension and is chaemia heart disease because sound evokes reflex responses that elevate adrenaline levels, triggers narrowing of the blood vessels.
Sound levels of road traffic constrict the arterial blood flow and raises blood flow. High noise level, on its own, produces natural stress reaction resulting in increased frequency of headache, fatigue, stomach ulcers and vertigo.
5. Mental Illness
Exposure to high levels of noise has been associated with the development of neurosis, including disengagement and increased aggressive behavior. The use or consumption of tranquilizers and sleeping peels is higher in noise exposed persons, besides psychiatric symptoms and admission rates, all suggest effects of noise.
Noise Control Measures
It is necessary to control noise for the good of everyone. The existing legislation needs to be enforced. For instance, the Federal Environmental Protection Agency (FEPA) guidelines on noise exposure limits provide a limit of 90db for an 8hr period in an industry, violation of which attracts sanctions under the law.
The Mineral Oil Safety Regulation (MOSR) requires operators in the oil industries to provide hearing protection devices for workers exposed to noise levels equal or greater than 85db for 8hr time weighted average, and no unprotected person is to be exposed to noise levels equal to 115db for any length of time.
Noise is limited to 50db at night in residential areas. Besides, personnel annual medical check is to include audiometric test.
The use of power generating sets is rift, especially in commercial areas. It follows therefore, that control measures will include the following:
– Public enlightenment through the media
– Health talk for noise generators
– Planning and organizing marketing areas for electronics and
– Education of itinerant hawkers of musical wares on noise pollution and sales management.
For the general population, noise can be reduced by the following measures:
– Provision of adequate and functional amenities and securities
– Sanctioning religious and other generators of excessive noise at night and during the day.
In conclusion, noise is a common phenomenon especially in most developing countries where the most desirable legislative control measures are not in place. Noises at excessive levels affect human health and there is the need for authorities concerned to do something on it.
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