17. Noise Pollution

Noise pollution refers to the presence of excessive, unwanted, or disturbing sound in the environment — arising from sources such as heavy road, rail, and air traffic, industrial machinery and factories, construction activity, loudspeakers, firecrackers, and other sources — at a level sufficiently high or persistent to cause discomfort, annoyance, or measurable harm to human health and well-being, or to disturb the natural behaviour of wildlife. Loudness (and hence the intensity of noise) is measured in decibels (dB); sustained exposure to sound levels above roughly 85 decibels is generally considered capable of causing gradual, cumulative, and potentially permanent damage to hearing, while very high, sudden, intense noise (such as an explosion or a very loud firecracker at close range, sometimes exceeding 120–140 dB) can cause immediate and severe hearing damage.

Well-documented harmful effects of chronic or excessive noise pollution include: gradual, and in serious cases permanent, hearing loss or impairment; sleep disturbance and consequent chronic fatigue; elevated stress levels, anxiety, irritability, and related psychological effects; measurable increases in blood pressure and cardiovascular strain with long-term exposure; reduced concentration and impaired cognitive performance, particularly affecting children's learning and memory; and, in the case of wildlife, significant disruption of animals' normal behaviour, including their ability to communicate, navigate, hunt, and avoid predators (this concern is especially significant for marine animals such as whales and dolphins, whose reliance on sound for communication and echolocation makes them particularly vulnerable to underwater noise pollution from ship traffic, sonar, and industrial activity).

Common measures adopted to control and mitigate noise pollution include: the setting and enforcement of statutory permissible noise limits for different categories of areas (such as separately defined limits for silence zones — typically areas around hospitals, schools, and courts — as well as residential, commercial, and industrial zones, and separate day-time and night-time limits) under environmental regulations (in India, these are notified under the Noise Pollution (Regulation and Control) Rules, framed under the Environment (Protection) Act); the use of sound-insulating and sound-absorbing materials in the construction of buildings located near busy roads, airports, or industrial areas; the planting of trees and green belts along highways and around noise-generating facilities, which helps absorb and diffuse sound; the regulation and, in many areas, restriction of the use of loudspeakers, especially during night-time hours; and the promotion of quieter machinery, vehicles, and industrial equipment through technological improvements and stricter regulatory standards.