Noise Pollution man-made noise harmful to health or welfare. Transportation vehicles are the worst offenders, with aircraft, railroad stock, trucks, buses, automobiles, and motorcycles all producing excessive noise. Noise intensity is measured in decibel (dB) units. Subject to 45 dB of noise, the average person cannot sleep. At 120 dB the ear registers pain; hearing damage begins at a much lower level, about 85 dB.
In Bangladesh noise pollution (also termed as sound pollution) is a major health hazard. In fact, due to noise pollution millions of people in Bangladesh are exposed to a number of health risks - from deafness to heart attack. On city streets noise pollution can be caused by hydraulic horns of vehicles, microphones and cassette players. The hydraulic horns used by buses, trucks and scooters in the crowded city streets are dangerous for human being. This is also how noise pollution in Dhaka City is affecting the hearing power of thousands of children everyday. The horns especially cause serious damage to children. Experts say, if a child below three years of age hears a horn emitting 100 dB of noise from a close range, he or she might lose his or her hearing power. A child's health may also be adversely affected by loud sounds from the radio, television, cassette players and microphones, the sound of mills and factories and loud noise.
The unit of sound frequency is hertz. Human beings usually hear 15 to 20 kilohertz (KHz) frequency sound. According to the World Health Organisation (WHO), generally 60 dB sound can make a man deaf temporarily and 100 dB sound can cause complete deafness. But the noise of any busy street in Dhaka has been estimated at 60 to 80 dB, with the sound of vehicles being 95 dB, loud speakers 90 to 100 dB, mills and factories 80 to 90 dB, restaurants and cinema halls 75 to 90 dB, festivals 85 to 90 dB, scooter or motorbike 87 to 92 dB and trucks and buses 92 to 94 dB. But the desired sound measure is 25 dB in the bedroom, 40 dB in the dining or drawing room, 35-40 dB in the office, 30-40 dB in the class room, 35-40 dB in the library, 20-35 dB in hospital, 40-60 dB in a restaurant and 45 dB in the city at night. When the sound exceeds this limit, there is noise pollution. Noise pollution beyond the limit destroys hearing and might even lead to the losing of one's mental balance. Noise pollution also causes peevish temperament, affects lungs, hampers the intellect of the children and makes them apathetic towards their studies.
According to a survey of the Department of Environment (DOE), noise causes mental and physical illness among the people. It causes high blood pressure, tachycardia, headache, indigestion, peptic ulcer, and also affects sound sleep. Anyone may become deaf for the time being if 100 dB or more noise pollution occurs for half an hour or more in any place. Working in an atmosphere of loud noise for a long period can cause complete deafness to any person. Any sort of noise pollution seriously affects expecting mothers. It has been observed that pregnant mothers living near big airports give birth to more crippled, deformed and immature children than those living in other places.
According to the DOE the perfect sound condition for Bangladesh is 45 dB for the daytime and 35 dB for the night in peaceful areas, 50 dB for the daytime and 40 dB for the night in residential areas, 60 dB for the daytime and 50 dB for the night in mixed areas (residential, commercial and industrial localities), 70 dB for the daytime and 60 dB for the night in commercial areas and 75 dB for the daytime and 70 dB for the night in industrial areas.
Another survey of DOE shows that noise pollution has increased in different parts of Dhaka City. The survey indicates that at Shaheen School the noise level is 83 dB during daytime and 74 dB at night. At Motijheel Government High School the noise level is 83 dB during daytime and 79 dB at night, at Dhanmondi Government Boys School 80 dB during daytime and 75 dB at night, at Azimpur Girls' College 80 dB during daytime and 74 dB at night, at Tejgaon Girls' College 75 dB during daytime and 67 dB at night, at Bangabandhu Sheikh Mujib Medical University 82 dB during day and 74 dB at night, at Dhaka Medical College Hospital 80 dB during the day and 69 dB at night, at Mitford Hospital 76 dB during the day and 73 dB at night and at Shishu Hospital 72 dB during the day and 69 dB at night.
Noise pollution is a health hazard. But, in Bangladesh, little has been done so far to reduce noise pollution. The authority concerned must create awareness among the people so that in the long run people can eradicate noise pollution from the country once for all. [Sifatul Quader Chowdhury]
See also environment.