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The World Health Organisation (WHO) says that around 5.0 per cent of the world population suffers from noise pollution. The safe limit of sound is 45 decibel (dB). Sound over 65dB may cause heart disease, over 90dB ulcer, hearing problems and changes of nerve system, and over 120dB pain in the ears and destroy hearing ability gradually.
Here, in Bangladesh, the Noise Pollution (Control) Rules 2006 says that the acceptable sound limit in the silent areas is 50 dB for the daytime and 40dB for night; in residential areas 55dB for day and 45dB for night; in the mixed areas 60dB for day and 50dB for night; in commercial areas 70dB for day and 60dB for night; and in the industrial areas 75dB for day and 70dB for night. The guidelines say exceeding the maximum noise level in certain areas is a punishable offence.
Studies show that at least 45 areas in Dhaka city are extremely polluted by noise. According to a recent study, the average sound level is 80-110dB in Dhaka's prime areas like Farmgate, Karwan Bazar, Shahbagh, Gabtoli and Mohakhali Bus Terminal.
According to a 2017 study by the Department of Environment (DoE), sound levels at all the divisional headquarters are far beyond the acceptable limit for human ears. The survey was conducted at 70 points of Dhaka city and recorded sound level reached up to 120-130dB at many points.
This study revealed that around 11.7 per cent of the population of the country had lost their hearing due to noise pollution. According to the report, the noise level was above 120dB during the daytime at Gabtoli, Arambagh intersection, Gulshan-2 intersection, Gulistan intersection, Mirpur 10 intersection, Banglamotor, New Market, Mascot Plaza of Uttara, Jagannath University and other areas. Among the 70 points, the lowest sound level was recorded 99.6dB during the daytime and 43.7dB at night at Road-18 of Uttara-14. The highest noise level recorded at Farmgate was 130.2dB during the daytime and the lowest 65.7dB at night. It also found that 500-1,000 vehicles in Dhaka sound the horn at the same time even when they are stuck in traffic.
WHO has described noise pollution as an underestimated threat that can cause hearing loss, cardiovascular problems, cognitive impairment, stress and depression. Noise pollution can affect people in several ways, some of which are listed below:
n HEARING LOSS: Exposure to noise can damage our hearing. Hearing impairment due to noise pollution can either be temporary or permanent. Long or repeated exposure to sounds at or above 85 dB produces damaging effects on the ear.
When ear is exposed to extreme loud noise (above 100dB) for a considerable period of time, it can cause irreparable damage to our ear. These sounds can damage sensitive structures in the inner ear and cause noise-induced hearing loss (NIHL), which can be immediate or it can take a long time to be evident. But the louder the sound, the shorter the amount of time it takes for NIHL to happen. It can be temporary or permanent and it can affect one ear or the both. In this case, victims are usually unable to understand when they talk to each other -- especially over the phone or in a noisy environment.
n POOR COGNITIVE OUTCOME: Regular experience of loud noise significantly over the time decreases the ability to read, learn and understand. Problem solving competencies and the ability to memorise may also decline due to frequent bombardment of noise. Noise pollution can also increase the margin of error that hampers our productivity at office.
In our everyday life, cognitive tasks are often performed in the presence of task-irrelevant environmental noise. Research has proved that children studying in noisy environment tend to show relatively low cognitive function. In healthy adults, environmental noise adversely affects many cognitive domains.
n CARDIOVASCULAR DISEASE: A noisy environment can be a great source of heart-related problems. A recent study shows that high intensity of sound causes a dramatic rise to blood pressure as noise levels constrict the arteries. With this, disruption of blood flow and number of heart beats per minute also increase. The study also reveals that the heart rate of the people who live in a noisy environment is greater than the people who are living in a less noisy environment. These sudden abnormal changes in blood increase the likelihood of cardiovascular diseases in the long run.
n SLEEP DISTURBANCES: Both the developed and developing countries are gradually becoming noisier places. But sleep is an essential part of human life, development and well-being. Sleeping difficulty due to exposure to high decibel noise can deter our overall well-being and hence, noise pollution has been described as the 'modern unseen plague.'
Noise can interrupt a good night's sound sleep. When it occurs, the person feels extremely annoyed and uncomfortable. Those who cannot enjoy sound sleep show a sharp dip in their energy levels, which often results in extreme fatigue. This can considerably decrease a person's ability to work efficiently.
n TROUBLE IN COMMUNICATING: Noise can be external or internal and it can interrupt the communication process at any point. But verbal communication is absolutely necessary for workplace communication. A noisy environment that produces more than 50-60 dB simply does not allow two people to communicate properly. Interpreting the speech of a second person becomes quite difficult and may lead to misunderstanding.
n VARIOUS OTHER PHYSICAL OR MENTAL LOSSES: Exposure to loud sound can lead to stimulate violent behaviour. Continuous noise in the vicinity can also trigger headaches; make people tense and anxious and disturb emotional balance. Sound pollution is likely to distort the natural tempo of our speech. People may experience difficulty while speaking. Generally, explosive sound, produced by vehicular traffic and aeroplanes, tends to produce such problems.
n ANNOYANCE: Sound pollution is one of the reasons of annoyance. Excessive sound pollution makes people irritated; they feel some sort of unnaturalness and excitement, which is marked in their behaviour. A nervous sort of a man, of course, is by nature more prone to such discomfiture and discomfort.
n GETTING TIRED AND EXHAUSTED: Sound pollution makes people tired and exhausted. People usually engage in different types of profession. But those engaged in different jobs suffer from exhaustion or apathy in work and such tendencies gradually put strain on their efficiency.
OCCUPATIONAL HEALTH HAZARD: Occupational health hazard has become one of the most significant issues of modern industrial workplace. A recent study reveals that millions of workers around the world are exposed every year to noise levels that put their hearing at risk.
Workers of several professions face more or less noise hazards every day, but ready-made garments (RMG) industry workers are the worst sufferers. A sustainable noise management system is urgently needed for implementing the core concept of occupational health and safety in workplaces.
The hazards of noise are dose-related. The higher the dose of noise a worker receives, the greater the risk to the worker's hearing. A worker's noise dose is dependent on the following three factors:
n Intensity/loudness: As per the International Labour Organisation (ILO), 60dB is for normal conversation; maximum 85 dB is recommended for eight hours in a working day.
n Frequency: Frequencies between 3000-4000 Hz are most likely to damage human hearing.
n Duration: The length of time one is exposed to noise.
The decibel (dB) level acceptable under ILO and Occupational Safety and Health Administration (OSHA) of USA for an eight-hour day cannot exceed 85-90 dB; for six hours the limit is 92 dB; for four hours the maximum limit is 95 dB; for three hours the limit is 97 dB; for two hours 100 dB; for one and a half hours 102 dB and for one hour 105 dB.
Perhaps the most significant fact with regard to noise pollution in Bangladesh is our backdated rules and regulations, poor monitoring system and poor implementation policy. Therefore, a well-devised noise management policy is need of the hour. Also, it is high time the government took meaningful initiatives to update the existing Noise Pollution (Control) Rules 2006.
Rana Dutta is Assistant Deputy Secretary, BKMEA.