Impact Wrench (pneumatic)
93 dB(A)
A typical level for impact wrench (pneumatic) on a UK site, how quickly a day at that level crosses each action value, the hearing protection that fits it, and the controls that reduce it at source.
Hearing protection
Ear defenders (SNR 25+)
Controls at source
- Cordless impact preferred (lower noise).
- Hearing protection mandatory.
- Time limits monitored.
Questions people ask
How long can someone do impact wrench (pneumatic) before it is a problem?
At a typical 93 dB(A), the daily exposure reaches the 80 dB(A) lower action value after 24 minutes, the 85 dB(A) upper action value after 1.3 hours and the 87 dB(A) limit value after 2 hours, if nothing else noisy happens that day. Control of Noise at Work Regulations 2005. Guidance, not legal advice.
What hearing protection is right for this?
Ear defenders (SNR 25+). The protection has to bring the level at the ear under 87 dB(A) without over-protecting to the point where people cannot hear a reversing alarm or a shout. Match the SNR to the level, do not just hand out the heaviest defenders in the van.
Does hearing protection count towards the action values?
No. The 80 and 85 dB(A) action values are assessed at the ear without protection, because the law wants noise reduced at source first. Only the 87 dB(A) limit value takes protection into account.
Why does 3 dB matter so much?
Decibels are logarithmic. Every 3 dB doubles the sound energy, so the time to reach an action value halves. Dropping a task from 95 to 92 dB(A) with a quieter blade or a screen buys twice the working time before the same exposure is reached.
Is a survey needed?
The library level is typical for the activity. If your estimate lands anywhere near 85 dB(A), measure it with a calibrated meter on your site; the actual level depends on the tool, the material and the surroundings. At this level, assume a survey and a hearing protection zone are needed.
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