Noise is probably the most frequently forgotten of the environmental pollutants, yet its effects can be many and far-reaching.

Noise may not seem as harmful as the contamination of air or water, but it is a pollution problem that affects human health and can contribute to a general deterioration of environmental quality.

Noise is undesirable and unwanted sound.

Not all sound is noise. What may be considered as music to one person may be noise to another! It is not a substance that can accumulate in the environment like most other pollutants. Sound is measured in a unit called the 'decibel' (dB).

The differences between sound and noise are often subjective and a matter of personal opinion. There are, however, some very harmful effects caused by exposure to high sound levels. These effects can range in severity from being extremely annoying to being extremely painful and hazardous.

Decibel levels of common sounds

dB 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 1m)

70 Average radio

74 Light traffic noise

90 Subway train

100 Symphony orchestra