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When is a workplace noise risk assessment required?
When should noise assessments be carried out?
This is a question that often comes up. Businesses are normally aware of The Control of Noise at Work Regulations 2005and of the general requirement to conduct risk assessments. They are also aware that there are ‘Exposure Action Values’or‘Exposure Limit Values’ within those regulations.
In addition, they often have an awareness of how noise measurements are taken i.e. using some kind of instrumentation. But when is a survey needed? Noise (along with a lot of the hazards that Occupational Hygienists are called into to help quantify) is a tricky one. For two main reasons:-
Noise levels often fluctuate over time and from location to location – the larger the uncertainty, the harder it is to know what is going on.
- Noise is measured using units of measurement which are not intuitive. Noise is measured in decibels and often expressed in terms of a ‘dose equivalence’– an Leq value. Again, this is not something that is immediately easy to grasp for non-specialists.
The easy answer to the question of ‘When are noise risk assessments are required?’ is to say – when you know that noise is a hazard that is present, but you can’t decide on the level of risk using pertinent knowledge or experience. So really the main point of a noise risk assessment is to remove uncertainty and to allow the employer to make a valid decision about whether employees are at risk.
Other reasons that noise assessments are required
Having shown there is a risk, to help understand how to prevent or adequately control that exposure.
To demonstrate that control is being maintained.
Measuring noise and using the rule of thumb
The degree to which there is variation in noise levels over time or from location to location will dictate how you measure noise. Three examples are shown below.
From left to right:
Steady noise – an example might be standing in a boiler room with plant operating
Cyclical noise – an example could be a machine like a press going through repeated operations
Variable noise – an example could be noise in a woodworking shop as different equipment gets used.
Where the noise is limited in variation (short periods with limited equipment) it might be possible to use rules of thumb to assess how close you might be to an action limit and therefore whether quantification is needed. The following are based on guidance from the HSE.
- Lower exposure action value – daily or weekly personal noise exposure (LEP,d or LEP,w) of 80dB. As a general rule of thumb, the noise level is probably 80db or more if the noise is intrusive but a normal conversation is possible between people 2 m apart – comparable to a busy street, a typical vacuum cleaner or a crowded restaurant.
- Upper exposure action value – daily or weekly personal noise exposure (LEP,d or LEP,w) of 85dB. As a general rule of thumb, the noise level is probably 85 dB or more if it is necessary to shout to talk to someone 2 m away, for more than about two hours per day in total.
For the examples given for steady or cyclical noise, these rules of thumb could help you complete a risk assessment.
However, where is significant variation over time or location (where people are working in different areas or using multiple noise-generating equipment), noise is generated over extended periods, hearing protection is used for control or there have been staff complaints, a noise survey would be recommended to more accurately estimate the exposure levels.
Where noise assessment are completed it is important to plan out in advance what is required to obtain the best data in a limited amount of time.
The information required at this stage includes the number of exposed workers, the characteristics of their activities and the identification of any noise sources, the way in which the activities are organised and how they change as a function of time.
Once a plan is in place surveying starts. A simplistic breakdown would be to allow for:-
- Measuring point sources using a sound level meter – this can be used to develop a noise map across a site as well as identifying the potential contribution from one source/activity to someone’s noise dose over a day or week.
- Using personal dosimeters on key staff to show how a person or group’s exposure may vary for a ‘typical’ day. Dosimeters are particularly useful when workers undertake a lot of different activities or work in different locations frequently.
Once the data is obtained an analysis is conducted to estimate where the employer sits in terms of compliance. If diary data is available on work patterns, this can be used to build up a clearer picture of what happens or might happen on other days. Recommendations are made to indicate where the action is required to meet the regulations e.gl. noise reduction, the provision of adequate hearing protection, the need for health surveillance or for improved training of staff.
In House can provide Workplace Noise Surveys and Management for your business premises in any industry sector.
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