ENVIRONMENTAL STUDIES(ES)

ENVIRONMENTAL STUDIES

Lesson 18: Noise pollution

Additional information

Measurements of noise pollution:
Noise is measured in “decibel”. Decibel levels of common sounds.

Decibel	Environmental condition
0	Threshold of hearing
10	Rustle of leaves
20	Broadcasting studio
30	Bedroom at night
40	Library
50	Quiet Office
60	Conversational speech (at 1 m)
70	Average radio
74	Light traffic noise
90	Subway train
100	Symphony orchestra
110	Rock band
120	Aircraft take off
146	Threshold of pain

1. Below a sound level of 80db hearing loss does not occurs.
2. 1 hour exposure to a 100db sound level can produce a “temporary threshold limit”.
3. Exposure to 95db for 8 hours every day for a period of 10 hours may cause about 15db of “noise-induced permanent threshold limit”.

Permitted noise levels:

Zone	Day – time db	Night – time db
Silent zone	50	40
Residential zone	55	45
Commercial zone	65	55
Industrial zone	70	70