The noise level in a workplace is considered harmful to health if it exceeds the exposure standard, which refers to an average noise level of 85 decibels (A-weighted) over an eight-hour period, and a maximum of 140 decibels (C-weighted).
As an indicator, some examples of noise levels include:
- jet engine – 120 decibels
- angle grinding – 120 decibels
- chain saw – 110 decibels
- lawn mowing – 93 decibels
- welding – 91 decibels
- front end loader – 85 decibels
- normal conversation – 60 decibels
There is a chance that the exposure standard may be exceeded if:
- it is difficult to hear someone speaking to you from one metre away
- employees notice a temporary hearing loss or ringing in the ears after leaving work
- employees need to use hearing protectors
If you provide hearing protectors to control your employees' noise exposure so that it does not exceed the noise exposure standard, you must provide audiometric testing for those employees ('mandatory audiometric testing')
If you're not sure that the standard is being exceeded, you must determine employees' exposure to noise. You could do this by taking some spot noise measurements or getting a noise specialist to come in and help you.
The more complex the situation, the more knowledgeable and experienced the person doing the assessment needs to be. In some cases, such as when there are multiple sources of noise, the assessment will be more difficult, and hiring an experienced consultant may be the best approach.
The effect of hearing protectors must not be taken into account in determining employees' exposure to noise.