What are the limits for noise at work?
In a noise assessment, we are comparing the noise levels faced by staff to the limits set by the HSE in the Noise Regs.
There are different limits for average and peak noise, called dB(A) and dB(C), where the A is the average over a shift, and the C is peak or impact noise.
When the noise assessment identifies the workplace noise is reaching one or more of the limits, then several requirements kick-in for the employer.
A good noise assessment should make it clear what the workplace noise is and also make it clear for the employer what is needed next.
Some additional explanation
If you are new to noise assessment and noise safety, some of the terms may not make absolute sense initially, so this may help.
Who is at work?
The Noise Regs and the noise limits apply to people who are at work. So that is paid employees, but also people such as volunteers - being ‘at work’ doesn’t automatically mean being paid. For example, volunteers in a local theatre are ‘at work’ on the evenings they are there.
The Noise Regs do not apply to social noise, so for example people attending music event. The paying public are not at work so the Noise Regs do not apply, however the people running the event are at work so the Regs and noise limits do apply to them.
Averages versus peaks in noise assessment
Remember, the dB(A) limits of 80 and 85 are averages for a day, not peaks. So if it is 88 dB(A) for ten minutes and quiet otherwise, then you are fine.
If you are curious, the Noise Exposure Calculator on this site can show how time impacts the noise exposure level. Enter the noise level and exposure time and it will calculate the daily noise exposure for you.
dB(C) is however instantaneous - duration doesn’t matter.
Levels are before hearing protection is taken into account
The 80 and 85 dB(A) and the 135 and 137 dB(C) limits mean the noise in the workplace, not the noise people receive underneath any hearing protection.
If you are close to the 80 dB(A), do a noise assessment
The HSE say that if you think your noise levels may be close to the 80 dB(A) limit, so maybe 78 or 79 dB(A), then you should do a noise assessment anyway as daily variations can easily be such that the noise is higher on some days.
If close to 85dB(A) assume it is over
Similarly, as noise is not a fixed point and does vary, the Noise Regs say that if a noise assessment identifies a noise exposure to be close to the 85 dB(A) limit then it should be treated as meeting it.
80 dB(A) or 135 dB(C)
This is a raised eyebrow and a 'we may have a bit of a problem here'. (The HSE didn't use that precise wording which is their loss 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.
Give employees training about noise including what the noise levels are.
Provide hearing protection but the employees can choose whether to use it.
Sign the areas as optional hearing protection.
Reduce noise levels where is a practical or possible to do so.
85 dB(A) or 137 dB(C)
This is the biggie and again applies if the noise assessment identifies the levels reach either one of them, not necessarily both.
Eliminate or reduce the noise levels by means such as engineering the noise out, or limiting exposure times via things such as job rotation.
Hearing protection is now mandatory - everyone exposed must wear it.
Use of hearing protection must be monitored and enforced. Issuing it and telling employees to wear it is not sufficient to meet the employer’s legal duties.
You need to do audiometric testing (health surveillance). This must be done in work-time and it cannot be optional, employees must attend.
87dB(A)
I will mention this fifth number as it is a specific limit but don't get too excited and distracted by it as it almost never applies.
87dB(A) is the absolute maximum noise level a worker may experience under the hearing protection.
This one is the level they actually hear under the hearing protection, whereas the other limits are the noise itself and are before the impact of hearing protection is considered.
But, and this is not just 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 up to 87dB(A) under the protection.
In reality there are very very few instances where this fifth limit is applied. Put it this way, in my 30-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.