Noise at Work Regulations: Measuring Noise on Site

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To measure noise on a construction site, you estimate or measure how loud each noisy task is and how long each worker is exposed to it, then combine the two into a daily personal noise exposure. You compare that figure with the limits in the Control of Noise at Work Regulations 2005: action values of 80 and 85 dB(A), an exposure limit of 87 dB(A), and peak values of 135, 137 and 140 dB(C). Measurement is done with an integrating sound level meter or a personal noise dosemeter, although HSE is clear that a reliable estimate from good data is often enough.

If your team needs a grounding in the risks and the rules before you start, our Noise Awareness e-learning module covers the simple science, the main laws and the noise level limits in under an hour.

What are the noise limits under the Noise at Work Regulations?

The Control of Noise at Work Regulations 2005 replaced the Noise at Work Regulations 1989 and came into force for most industries on 6 April 2006. They require employers to act at levels 5 dB(A) lower than the old rules. Regulation 4 sets three levels, each with a daily or weekly exposure value and a peak value:

Level	Daily or weekly exposure	Peak sound pressure	What the employer must do
Lower exposure action value	80 dB(A)	135 dB(C)	Assess the risk, give information, instruction and training, and make hearing protection available to anyone who asks for it
Upper exposure action value	85 dB(A)	137 dB(C)	Run a planned programme of noise control, provide hearing protection and make sure it is worn, mark hearing protection zones with signs, and provide hearing checks
Exposure limit value	87 dB(A)	140 dB(C)	Must not be exceeded. This is the only level where the protection given by hearing protectors is taken into account

The A-weighted figures describe exposure averaged over a working day (or a week, where exposure varies markedly from day to day). The C-weighted figures describe peak sound pressure, the sudden bangs from impacts, cartridge-operated tools and breakers. Both must be assessed.

Do you have a noise problem on site?

Before buying or hiring any equipment, run the simple checks in HSE construction noise guidance. You will probably need to do something about noise if workers:

have to raise their voices to talk while about 2 metres apart for at least part of the day
use noisy powered tools or machinery for more than half an hour a day
are exposed to impact noise, such as breakers or pneumatic drills, or explosive sources such as cartridge-operated tools

HSE lists concrete breakers, pokers, compactors, sanders, grinders, disc cutters, hammer drills, chipping hammers, cartridge tools, scabblers and needle guns as the tools that put workers at higher risk, along with anyone working close to heavy plant. HSE guidance L108 also gives a quick rule of thumb for whether a risk assessment is needed:

What you notice	Probable noise level	Assessment needed if it lasts more than
Noise is intrusive but normal conversation is possible	80 dB(A)	6 hours
You have to shout to talk to someone 2 m away	85 dB(A)	2 hours
You have to shout to talk to someone 1 m away	90 dB(A)	45 minutes

Sound level meters vs dosimeters

If you cannot get reliable figures from manufacturers, similar sites or published data, you will need to measure. HSE guidance L108 describes two main instruments:

	Integrating sound level meter	Noise dosemeter (dosimeter)
How it is used	Hand held by the person measuring, who follows the worker	Worn on the worker, with the microphone on the shoulder
Best for	Fixed tasks and work locations you can stand next to	Highly mobile workers, hard to reach areas and whole shift measurements
Standard to look for	BS EN 61672-1 Class 1 or 2	BS EN 61252
Peak readings	Set to C-weighted peak to measure LCpeak	If it shows a peak action value exceeded, check with a sound level meter

Whichever you use, a few rules from HSE keep the results reliable:

Check the meter with its matching sound calibrator before and after measuring. The reading should stay within 1 dB.
If the meter or calibrator is more than two years old, it should have passed a verification test within the last two years.
With a sound level meter, measure where the worker’s head would be, on the louder side, and no closer than 15 cm to their head.
Measure long enough to be representative: short for steady noise, three or more cycles for cyclic work, and until the reading settles for changing noise.
Do not rely on smartphone apps. HSE warns they cannot meet the instrument standards and can be more than 10 dB out.

Using the HSE noise calculator

A reading in decibels is not your exposure. Daily personal noise exposure (LEP,d) combines how loud each task is with how long the worker spends on it. HSE publishes free noise exposure calculators and ready-reckoners: enter the noise level and duration of each task to get a daily figure, or use the weekly version where exposure varies markedly from day to day. HSE also provides hearing protection calculators to check that the protectors you choose are good enough.

Two points catch people out. First, do not make any allowance for hearing protection when you estimate exposure against the action values. Second, time matters less than you might think: HSE notes that a quiet refuge used for half a shift achieves no more than a 3 dB reduction in a worker’s exposure, so reducing noise at source usually does more than shortening the task.

What to do with the results

Under regulation 5, you must record the significant findings of your risk assessment and the measures you have taken or plan to take. On a construction site, HSE suggests controls such as:

using quieter methods, such as block splitters instead of cut-off saws, or bursting and crushing instead of pneumatic drilling
choosing low noise tools and fitting mufflers, silencers and sound panels
putting up temporary barriers, using noise exclusion zones and keeping walkways away from noisy work
rotating workers and planning quieter days to limit exposure
providing hearing protection as a last line of defence, not instead of noise control, and avoiding overprotection so people can still hear warnings and traffic

Hearing checks are needed for workers regularly exposed above the upper action value or at particular risk. HSE suggests checks annually for the first two years and then every three years. Review the assessment when the work changes, and do not leave it more than about two years without checking. The general duties behind all of this come from the Act explained in our guide to what the Health and Safety at Work Act 1974 covers.

Building noise awareness in your team

The law requires information, instruction and training for everyone exposed at or above the lower action value. Our Noise Awareness module takes 55 minutes and shows how dangerous noise can be in the workplace, the main laws and noise level limits, the specific health risks, and how risk assessments, action plans and the right personal protective equipment reduce them. It sits alongside more than 180 on demand e-learning courses, and managers can track their team’s progress and results.

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FAQs

What is the legal noise limit at work in the UK?

The exposure limit value is a daily or weekly personal noise exposure of 87 dB(A), or a peak of 140 dB(C), taking account of hearing protection. Action is required from 80 dB(A) and 135 dB(C), with stricter duties from 85 dB(A) and 137 dB(C).

How do you measure decibels at work?

Use an integrating sound level meter to Class 1 or 2 of BS EN 61672-1, or a personal dosemeter to BS EN 61252, calibrated before and after use. Then combine the levels with exposure times, for example in the HSE noise exposure calculator.

Can I use a phone app to measure noise levels at work?

Not for compliance. HSE says smartphone apps cannot meet the standards for sound level meters and, depending on the app and the noise, can be more than 10 dB out.

What is the difference between dB(A) and dB(C) in the noise regulations?

The dB(A) values apply to daily or weekly average exposure. The dB(C) values apply to peak sound pressure from sudden, impulsive noise such as hammering or cartridge tools.

When must hearing protection be worn on site?

Where exposure is likely to reach the upper action value of 85 dB(A) or 137 dB(C), the employer must provide hearing protection, ensure it is used and mark the area as a hearing protection zone. Below that, from 80 dB(A), it must be available on request.

How often should a noise risk assessment be reviewed?

Whenever the work changes or there is reason to think it is no longer valid. HSE advises not to leave it for more than about two years without checking.

Measuring noise properly starts with people who understand why it matters. Give your team the essentials with our Noise Awareness e-learning module, or call 0333 444 0018 to talk to our team about training for your site.