Unit 26 Environmental Protection III 环境保护（下）

Part 6  Noise Pollution 噪音污染

    Noise is among the most pervasive pollutants today. Noise from road traffic, jet planes, jet skis, garbage trucks, construction equipment, manufacturing processes, lawn mowers, leaf blowers, and boom boxes, to name a few, are among the audible litter that are routinely broadcast into the air.

    Noise negatively affects human health and well-being. Problems related to noise include hearing loss, stress, high blood pressure, sleep loss, distraction and lost productivity, and a general reduction in the quality of life and opportunities for tranquillity.

    We experience noise in a number of ways. On some occasions, we can be both the cause and the victim of noise, such as when we are operating noisy appliances or equipment. There are also instances when we experience noise generated by others just as people experience second-hand smoke. While in both instances, noises are equally damaging, second-hand noise is more troubling because it has negative impacts on us but is put into the environment by others, without our consent.

    Noise pollution is not easily defined. Part of the difficulty lies in the fact that in some ways it is different from other forms of pollution. Noise is transient; once the pollution stops, the environment is free of it. This is not the case for chemicals, sewage, and other pollutants introduced into the air, soil, or water.

    The definition of noise itself is highly subjective. To some people the roar of an engine is satisfying or thrilling; to others it is an annoyance. Loud music may be enjoyable or a torment, depending on the listener and the circumstances. Broadly speaking, any form of unwelcome sound is noise pollution, whether it is the roar of a jet plane overhead or the sound of a barking dog a block away.

    The actual loudness of a sound is only one component of the effect it has on human beings. Other factors that have to be considered are the time and place, the duration, the source of the sound, and whether the listener has any control over it. Most people would not be bothered by the sound of a 21-gun salute on a special occasion. On the other hand, the thump-thump of a neighbour's music at 2 a.m., even if barely audible, could be a major source of stress.

    The decibel (dB) (分贝) is a measure of sound intensity; that is, the magnitude of the fluctuations in air pressure caused by sound waves. In fact, an increase of just 3 dB means twice as much sound, and an increase of 10 dB means ten times as much sound.

    A sound pressure level of 0 dB represents the threshold of hearing in the most sensitive frequency range of a young, healthy ear, while the thresholds of tickling or painful sensations in the ear occur at about 120 to 130 dB. There is fairly consistent evidence that prolonged exposure to noise levels at or above 80 dB can cause deafness. The amount of deafness depends upon the degree of exposure.

    Noise can cause annoyance and frustration as a result of interference, interruption and distraction. Exposure to noise is also associated with a range of possible physical effects including: colds, changes in blood pressure, other cardiovascular changes, increased general medical practice attendance, problems with the digestive system and general fatigue.

    通常所说的噪声污染是指人为活动而不是自然现象引起的。噪声污染是物理性污染，本身对人无害，只是在环境中的流量过高或过低时，才会造成污染或异常。物理性污染一般是局部性的，即一个噪声源不会影响很大的区域。

    另处，物理性污染没有后效作用，即噪声不会残存在环境中，噪声停止，污染立即消失。外界噪音污染主要来自航空、公路、铁路运输，以及工程施工和工业生产等；而室内噪音污染则来自风扇、电脑及其它家用电器。

    噪音污染不但能够影响人的听力，而且能够导致高血压、心脏病、记忆力衰退、注意力不集中及其它精神综合征。研究表明，人听觉最高可以接受30分贝的音量，当室内的持续噪音污染超过30分贝时，人的正常睡眠就会受到干扰，而持续生活在70分贝以上的噪音环境中，人的听力及身体健康将会受到影响。

    世界卫生组织(WHO)最近就全世界的噪音污染情况进行了分析调查，认为全球噪音污染已经成为影响人们身体健康和生活质量的严重问题，呼吁世界各国积极采取有效措施来控制减少噪音污染。

    为此，他们建议各国政府将治理噪音污染纳入国家的环保计划，将卫生组织的指导性标准视为噪音治理的长期目标，制定和实施有关噪音管理的法律法规，支持有关减少噪音的科学研究，

    制定和完善有关噪音的测量标准，鼓励有关噪音对环境和健康影响的研究，进一步加强有关噪音污染的宣传，让全社会重视噪音污染的危害，减少噪音污染对人类健康的影响。

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