In urban localities all over the world, noise pollution has been recognised as a major factor affecting public health and well being. It is an ever growing nuisance. Man-made sources are mainly responsible for increasing the ambient noise level in urban localities.

Automobiles, industrial units, low flying air-craft and loud speakers have been recognized as a major source of noise affecting large number of peoples. Thickly populated, poverty-stricken third world countries are however, the most affected ones, wherein the ill effects of noise pollution are rarely given serious attention. A survey in Delhi, Bombay and Calcutta conducted in 1988 revealed day time noise levels ranging between 60 dB to 90 dB in residential localities.

Many times during the day this level exceeded 100 dB. Near aerodromes, railway tracks, busy highways and industrial establishments a noise ranging between 95 to 105 dB has been recorded during most of the day time. On the basis of extensive studies World Health Organisation has recommending permissible noise levels for residential, industrial, commercial localities and silence zones.

Permissible Noise Levels in Different Types of Localities.

Locality Permissible noise levels (dB)

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Day Night

Industrial area

75

65

Commercial area

65

55

Residential area

55

45

Silence zones for hospitals,

45

35

educational institutions etc.