When is a noise assessment required?
It’s an interesting dilemma - how do you know you need to do a noise assessment without actually doing a noise assessment?
A noise assessment must be done by any employer who has noise levels exceeding 80dB(A), although it is recommended to have a full noise assessment if noise levels are thought to be around 78-79 dB(A) due to the natural variations each day.
The regulatory bit on this is that a noise risk assessment is needed where and employer has work which is ‘liable to expose employees to noise at or above a lower exposure action value’. In English, this means if there is a chance people may be working in noise levels of around 80 dB(A) or more then Regulation 5(1) requires a noise assessment to be done.
L108 has some guidance (not law) that ‘if you are in any doubt, it would be best to assume that the [a noise assessment is needed]’.
Industries where noise assessments are needed
This can cover almost any industry which has any kind of production or manufacturing process, but also more esoteric ones where noise may not initially seem integral to the jobs.
Education such as wood-working or music classes
How to identify if you need a noise assessment other than guessing
Those Satanic Overlords at the HSE have handily provided a nice table on this in L108, page 12:
The conversation test
Chances are this is how the HSE will decide if they want to see your noise assessment - if they go into a workplace and find noise intrusive while having a conversation with people then that is an indication the levels are around 80 dB(A) and they will ask to see an assessment.
Other sources of noise information
Any noise data provided by the manufacturer of the tool or equipment being used.
The very lovely website which you are currently reading gives an extensive list of noise levels for jobs and tools we ourselves have measured. That can give you a very good idea of whether there may be a problem or not.
A cheap Type 3 noise meter can be a big help in this part as a rough and ready indication of whether it's getting a bit loud.
Or even a phone app can give you a pointer, but if you do go down this route, make sure it is a good app and not one of the myriad of a bit rubbish free or sub £1.99 apps. The one I have used and would recommend is SPL Pro. It's not good enough for a noise assessment but is helpful as a general indicator if whether a proper assessment is needed.
Advice if you decide you do not need a noise assessment
The one thing to stress is, if you follow this process and decided that a noise assessment is not needed, then document that you went through the decision-making process, covering who was involved, how it was done and when it was done. That way when the HSE come knocking you can say 'yes my Benevolent Lord of Safety, we have checked to see if we needed a noise assessment and here is how and when we did it'. If you say you checked but have no proof of that then they will get a steely glint behind their monocle in their one good eye and pour forth their anger upon you as you cannot prove you did the check and to them you have probably just ignored the issue.
Remember if there is no proof or record of something being done then it didn't happen. And it's always better to have done the right thing and got a result they disagree with than to be thought not to have tried at all.