Exposure limits for noise at work
For work, we have FOUR main limits, two for dB(A) and two for dB(C) and a good noise assessment must cover them all. There is also another separate fifth dB(A) limit as four limits were clearly not enough.
For those who are already wishing they'd not started reading this, there is a page giving more info on what dB(A) and dB(C) mean - but put simply, dB(A) is kind of averaged over time, while dB(C) is a brief impact noise where time doesn't really matter, a short bang.
Not actually 'at work'?
Before diving into the specific noise limits, these exposure limits only apply to people who are experiencing noise at work. If you are not at work then there are no noise exposure limits. So in a club for example, the limits apply to the staff working there but not to the punters. 'Work' doesn't necessarily mean being paid to be there and would cover anyone who is working, so including volunteers, interns, contractors, etc.
So, after that preamble, the exposure limits...
80 dB(A) or 135 dB(C)
As the Noise Regs call it, this is the First Exposure Action Value. Think of this as being an initial identification of 'aye aye, we may have a bit of a problem here guv'. (The HSE for some reason didn't use that precise wording - can't see why as it describes it perfectly).
Meeting either of these, (it doesn't have to be both), is a sign that noise levels are getting too high and certain requirements kick in.
Do a noise assessment
If you have reason to believe the noise levels are reaching 80 dB(A) the first thing to do is a noise assessment if you haven't done one already.
Provide Hearing protection
Hearing protection should be made available to all employees affected by the noise but they have the choice of whether to use it or not. It is not mandatory under law at these levels.
Give Employee noise training
Employees should be told that the hearing protection is available and where the higher noise levels in the site are.
85 dB(A) or 137 dB(C)
This one is the biggie and again applies if the noise exposure hits either one of them, not necessarily both. This means your longer term noise levels may be quiet and give a low dB(A) result, say 82dB(A) but you have an occasional crash where the peak noise hits 139dB(C) - this would mean everything listed below still applies. (An example of this - packing warehouses which are generally fairly quiet but if someone drops a wooden pallet into place rather than lowering it, that bang on a concrete floor can exceed the 137dB(C) level even though it is quiet overall.)
Eliminate or reduce the noise levels
Firstly, if the noise assessment shows the noise levels meet or go over one of these two limits the employer has to try and eliminate the noise risk, or where not possible reduce the noise exposures to as low a level as is, wait for it... that magic phrase 'reasonably practicable'. This can be by changing machines, changing workplace layouts, using technical gubbins like enclosures or walls, maintenance programmes, changing shift patterns or job rotation, etc. Basically anything which can be done to get individual employees' noise exposure levels back to below the limit
Hearing protection becomes mandatory at this level or above, and employees cannot opt out of using it. And your workplace must be decorated with those lovely blue and white hearing protection signs. And the use of it must be enforced - no good providing it and putting signs up if you don't enforce it and you will lose any civil claims if you don't. If you want some help choosing protectors there is a database of around 200 types of hearing protection here which gives performance levels and approximate prices.
Audiometry / Health Surveillance
At these noise levels a programme of health surveillance, or 'hearing tests' as normal people would call them, becomes mandatory for employers. That's a whole other subject and if you really want to punish yourself there is a section of this site just dedicated to the health surveillance elements.
And as always, some specific noise awareness training is needed for employees who are regularly exceeding the 85 dB(A) or 137 dB(C) limits. The contents of this are pretty tightly specified in the Regs. and are a bit more than 'oi, it's noisy, put this on'. If you cast your eyes up and left you'll see a page all about what noise awareness training should cover.
I will mention this fifth number as it is a specific limit but don't get too excited and distracted by it. 87dB(A) is the absolute maximum noise level a worker may experience under the hearing protection. But, and this is not a big 'but' but is a bloody huuuuuuge 'but', exceeding the standard 85dB(A) limit under the protection is only allowed where there is absolutely no other way of reducing the noise experienced by the worker - so where there are no options for limiting exposure time, there are no engineering options available, no more powerful hearing protection is available, etc. Only where all these are met can a worker be exposed to up to 87dB(A) under the protection.
What happens if there is absolutely no way to reduce noise levels via engineering or exposure time controls and there are no hearing protectors on the market which are more powerful than the ones being worn and the employee is still being exposed to 88dB(A) or above under the protection? The answer is harsh but simple, the job cannot be done.
In reality there are very very few instances where this fifth limit is applied. Put it this way, in my 20-odd years working on noise issues including hundreds of different workplaces I've never come across a situation which met the criteria where the noise was so high there was no way to get the noise exposure under the protection back down to a safe level.