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close this bookFact sheet No 258: Occupational and Community Noise - February 2001 (WHO, 2001, 5 p.)
View the document(introduction...)
View the documentHealth impact
View the documentSound and the ear
View the documentCommunity noise
View the documentOccupational noise
View the documentOccupational exposure limits
View the documentWHO response

Occupational exposure limits

Occupational exposure limits specify the maximum sound pressure levels and exposure times to which nearly all workers may be repeatedly exposed without adverse effect on their ability to hear and understand normal speech. An occupational exposure limit of 85 dB for 8 hours should protect most people against a permanent hearing impairment induced by noise after 40 years of occupational exposure.(p.65, Exposure Criteria)

Noise reduction (ref Noise Sources p100)

Noise-induced hearing impairment is preventable.

· Protection against hazardous noise exposure should be included into overall hazard prevention and control programmes in workplaces.(p218) The dangers of noise should be recognized before workers start complaining of hearing difficulties.

Machine safety: A European Union Directive requires that the machines are so designed and constructed that hazards from the noise emissions are minimized. Declarations of the noise emissions of machines are required, to allow potential buyers not only to select the least hazardous equipment but also to calculate the noise impact at workplaces and to help with noise-control planning. (ref Noise Sources p.100 - 101)

· It is 10 times less expensive (unit cost per decibel reduction) to make noise-generating processes quieter than to make a barrier to screen the noise.(ref Engineering Noise Control p. 231)

Noise levels can be lowered by the use of noise-control enclosures, absorbers, silencers and baffles and by the use of personal protective equipment, such as earmuffs. Where technical methods are insufficient, noise exposure may be reduced by use of hearing protection and by administrative controls - such as limiting the time spent in noisy environment and scheduling noisy operations outside normal shifts or at distant locations.

Essential elements of noise control programmes are education and training of the workers as well as regular hearing tests. (ref. Hazard Prevention and Control Programmes p.221)