Vol. 5 Num 382 Fri. June 24, 2005  

Noise pollution: Needs immediate attention

Pollution is the undesirable state of the natural environment being contaminated with harmful substances as a consequence of human activities. It involves any contamination -- of air, soil, water, even loud noise and sound is also a part of pollution. Most of us are certainly thinking about 'Green House Effect' and other crucial environmental crises. At the same time at least a small segment of the urban people are also worried about the widely underestimated but serious environmental issue like 'noise pollution' -- environmental noise that is annoying, distracting or physically harmful -- also popularly known as 'sound pollution'.

Noise pollution should indeed be a great concern for people particularly living in urban areas. Urban people are engulfed with a variety of noises, viz, automobiles, construction equipment and plants, loud speakers, bomb blasts, hydraulic horns, aircraft sounds and so on.

In fact noise is one of the increasingly prevalent environmental pollutants. The day-night sound level of residential areas is considered not to exceed 55 decibels (db) to protect against activity interference and annoyance. But it is estimated that nearly half of the US population (more than 100 million people) live in areas where the noise exceeds this level. While looking at the European Union, Susan M Booker finds nearly 80 million people 20 percent of the EU population -- are exposed to noise levels high enough to cause adverse effects. She also suggests that in terms of cost such as lowered property market value, abatement measures, annoyance, prevention, medical care, and production losses, the annual cost of noise pollution has been estimated by the EC to be as high as E38 billion!

The above scenario illustrates the situation of developed countries, where vehicle horns are strictly prohibited, people normally do not create any public nuisance. Keeping in mind the above figures, one can easily assume the situation of developing and least developed countries. As Bangladeshi citizens, it is time to anxiously recognize Dhaka city scenario and decide on whether we should live there. Similar is the case with Chittagong. But the paradox is that we, the people living in these two cities, do not have any alternative. We should address the issue right at the moment.

Following table depicts various sources of sound with its intensity

Source of sound Intensity
Whisper 20 30 db
Normal conversation 40-60 db
Tape recorders or orchestra 70 db
Heavy traffic 90 db
Pneumatic drills and other machines 100 db
Generator 120 db
Jet engine (about 90-100 feet away)
140 db

Most of us are unaware of the effect of noise and do not take any preventive measure against noise pollution, resulting a considerable damage of potential human energy and productivity. Noise pollution has tremendous silent effect that we are willingly or unwillingly ignoring all the time, but time is running out, we must not ignore it any more, we have to know the consequences of noise pollution. Excessive noise is considered to be the number one cause of stress in urban living. Even something as benign as the sound of music in an apartment may cause annoyance to the next-door neighbours. Scientific findings suggest that noise pollution have a negative effect on human health. Constant exposure to noise does not only decrease quality of life but frustration with it can also be turned inward, manifesting in the body as tension. As a consequence it may lead to cause high blood pressure, heart disease, headache, ulcer and psychiatric problem.

The general hazards of noise pollution are, as found in relevant documents:
*Eardrum is damaged when exposed to very loud and sudden noises. The hair cells in the inner ear are chronically damaged. Prolonged exposure to noise of certain frequency pattern leads to hearing loss.

*Noise causes heart output to decrease with fluctuations in arterial blood pressure and vaso-constriction of peripheral blood vessels.

*Blood is thickened by excessive noise. Eosinophilia, hyperglycaemia, hypokalaemia and hypoglycaemia are caused by alteration in the blood due to noise.

* Noise affects sleep and work performance, especially of watch-repairers and others where precision is called for.

Some more specific ear damages suggested by Dr. Pankaj Tripathi are:
Temporary Deafness: This Persists for about 24 hours after exposure to loud noise.

Permanent Deafness: Repeated or continuous exposure to noise of around 100 db results in permanent hearing loss. Even single exposure to noise of 160 db can lead to rupture of eardrum and permanent deafness.

Auditory Fatigue: Noise of 90 db causes buzzing and whistling in the ears.

Besides, he suggests decreased work efficiency, increased intracranial pressure, increased blood pressure, increased heart rate, respiration rate and sweating, diminished Night Vision, Colour Perception and visual disturbances due to noise pollution.

Let us look at the effects of noise on our lovable children -- for whom we work hard and to whom we will leave the nation in future. The situation is rather disappointing. Literature suggests that noise pollution is linked to impaired cognitive development in children and to diminished short-term memory span.

At noise levels of 55 to 66 db, ability to concentrate is severely compromised or impossible for many children. Reliable studies have demonstrated this and conclude that exposure to high levels of noise can adversely affect reading ability in school-aged children. It has been revealed in a study that the reading and math scores of pupils in classrooms where noise was controlled were higher than those in classrooms where this was not the case. Children living on the bottom floors of an apartment building near heavy traffic for four years or longer, scored lower in reading ability tests than children residing on the top floors, further from the traffic.

Scientists found that noise affects several aspects of children's behavioral and psychological functioning, including learning to read as well as their chronic stress levels. Noise has two types of effects on children: one "nonauditory" effect and another "auditory" effect. The nonauditory effects of noise in children fall in two main categories: reading and other aspects of cognitive performance, and stress-related responses such as annoyance, blood pressure, secretion of stress-related hormones, and mental health. These two categories are also linked to the auditory effects of noise. A very important auditory effect of noise is interference with the intelligibility of speech. Hearing other people talk is critical to children's early language development. But trying to hear someone talk in a noisy environment can produce other nonauditory effects. Memory and performance can be impaired because of the extra effort required to decipher speech. The auditory and nonauditory effects of noise are often interlaced.

Considering the foregoing discussions the following steps can be taken by the authorities concerned for the betterment of the countrymen especially the city dwellers:

*Make people aware of the effects of noise

*Stop horn of vehicles on the city streets

*Ban the hydraulic horns of vehicles like those used by some bus, trucks etc.

*Ban private use of loud speakers, mikes etc., e.g., in election campaigns or other publicity

Scientists, academics, government, non-government and community-based organisations, development agencies, journalists and mass media people may take necessary steps in this regard so that we can make the country a noise-free place to live in.

Sorowar Chowdhury and Amar Krishna Baidya are development activists.