Noise

Over 1 million employees in Great Britain are exposed to levels of noise which put their hearing at risk.

Loud noise at work can permanently and irreversibly damage your hearing, particularly if it is excessive, or of prolonged duration. Therefore it is important that the University controls the exposure to noise of its employees and anyone else affected by it.

The Control of Noise at Work Regulations 2005 introduced a reduction in the action levels for noise at work and a change of emphasise towards controlling noise at source, wherever reasonably practicable, rather than relying on mitigating the effects of noise at the human ear. These changes will require Departments to re-evaluate their approach to sources of noise at work.

Departments and Institutions have a duty to:

• Assess the risks from noise at work, identify areas and people at risk
• Take action to reduce the noise exposure that produces those risks
• Reduce the noise by engineering controls wherever reasonably practicable
• Provide employees, students and visitors with hearing protection if the noise exposure can not be reduced by other methods
• Make sure the legal limits on noise exposure are NOT exceeded
• Provide employees, students and visitors with information, instruction and training
• Carry out health surveillance, including audiometry, wherever there is a risk to health

Exposure to noise at work is assessed as a function of both how 'loud' the noise is (measured in deci-Bels, dB) and how long an individual is exposed to that noise. Exposure to noise at work above the Regulation's lower action level of 80 dB (A), averaged over eight hours a day, will require actions to be taken by the Department or Institution to protect those exposed. The relationship of noise level and exposure time is such that if louder noises are experienced for shorter times the averaged first action level may still be exceeded (see below).

As a rough guide:

* This is the approximate time that the law allows an unprotected person to work in this level of noise each day, 5 days a week. However it does not mean that there is absolutely no risk to any persons hearing below the 80 dB (A) action level upon prolonged and repeated exposure.

The figures in the above table are approximations for a range of equipment types and are NOT a substitute for a professional noise survey of the actual equipment in use in the workplace.

Individual equipment will vary depending upon a range of factors including its make, model, age, condition, how well it has been maintained, what it is doing /how it is being used, which type and size of material it is working on/with etc.

If there are additional sources of noise in the work place, at the same time as a particular piece of equipment is in use, the noise level at the ear will be higher and the approximated exposure times shown above may be reduced.

Furthermore, if a person's exposure to noise were to reach their daily exposure limit in less than 8 hrs, they could only continue to work that day in an area below 68 dB for the rest of the day. Noise below 68 dB would not significantly add to the day's average exposure level (function of the logarithmic dB scale).

If a Department or Institution suspects it may have a problem associated with exposure to noise at work they should contact the Health and Safety Office to arrange a professional noise survey immediately.

Note: Some work environments within the University may have levels of noise which are a genuine 'nuisance' and may cause stress to the individuals being exposed to them, but are below the statutory action levels and therefore NOT covered by the Control of Noise at Work Regulations, 2005.

The Control of Noise at Work Regulations, 2005

The Regulations impose a hierarchy of control measures triggered by action values:

Lower Exposure Action values:

Daily exposure of 80 dB(A): as an average over 8 hrs.

Peak sound pressure of 135 dB(C): maximum single event noise level.

If either of these values is exceeded the Regulations require the noise to be controlled at source where reasonably practicable. If the control measures do not reduce the noise below the action values then hearing protection must be offered to those exposed. The University would expect hearing protection to be used and maintained in accordance with the Regulations.

Upper Exposure Action values:

Daily exposure of 85 dB(A): as an average over 8 hrs.

Peak sound pressure of 137 dB(C)): maximum single event noise level.

If either of these values is exceeded the Regulations require a formal program to control the noise at source where reasonably practicable. If the control measures do not reduce the noise below these action values then hearing protection must be used by those exposed above the upper action values.Furthermore the areas concerned must be delineated with warning signs as a compulsory hearing protection zone, and health surveillance provided through the University's Occupational health service for those at risk. The University would expect hearing protection to be used and maintained in accordance with the Regulations.

Note: You might just notice a 3 dB change in noise level because of the way the ears work. Yet every 3 dB increase doubles the noise; so what seems like small differences in deci-Bel numbers can be quite significant.

Noise Surveys:

As a rule of thumb: "If a person has to raise their voice to carry out a 'normal conversation' with a person 2 metres away, then the level of noise is excessive, and a noise survey is required".

As well as providing professional noise surveys and advice on control measures, the Health and Safety Office can carry out an 'Octave band Analysis' which will enable Departments and Institutions to select the appropriate hearing protection for the task. Octave band analysis is required since noise is made up of a spectrum of sound frequencies at different intensities. Attenuation across this sound spectrum is dependent upon the specific capabilities of the hearing protection under consideration. Attenuation data/information is supplied with the hearing protection and should be retained by the user (usually found on packaging or as a leaflet).

Control measures and/or hearing protection should reduce the noise at the ear to below 80 dB. Hearing protection should not completely attenuate all sound. If all sound were to be removed from the ear the individual would be unaware of audible safety warnings and unable to communicate efficiently. Octave band analysis will enable the residual sound level at the ear to be calculated for the specific hearing protection being considered.

Health surveillance:

Health surveillance in the form of audiometry (a hearing test) is available from the University's Occupational Health Service. It is required for anyone likely to be regularly exposed above the Upper Exposure Action Values or at risk for any reason eg: they have already suffered hearing loss, are particularly sensitive to damage or are working with ototoxic chemicals that exacerbate noise induced hearing loss. Annual health surveillance warns when a person is suffering from the early signs of irreversible damage and gives the opportunity to introduce further control measures where necessary. Records of health surveillance should be kept, made available to the employee and used to review the effectiveness of control measures.

Training:

Those potentially exposed to noise above the first action level should be given information, instruction and training including:

• The potential noise exposure and its risk to hearing
• What needs to be done to control exposure
• Where and how to obtain hearing protection
• How to correctly use and maintain hearing protection
• Their duty to wear it at all times in a designated hearing protection zone; even small exposure times can give large noise doses at high levels
• The health surveillance system.

Control Measures:

Controlling noise at source is preferable to mitigating its effects at the ear through hearing protection.

This can often be achieved by one or more of the following:

• Buying / using quieter equipment ie: having a 'buy quiet policy'.
• Using a different and quieter process.
• Introduce engineering controls.

Engineering controls can include:

• Avoid metal on metal impacts
• Add vibration damping panels
• Use vibration isolation mountings
• Fit silencers
• Fit sound proof enclosures around equipment
• Put workers in sound proof booths
• Erect sound barriers and screens
• Increase the spatial separation of noise and workers
• Fit sound absorbing material in workplace
• Limit time in noisy areas, halving time halves exposure
• Limit number of people in noisy areas

Further information:

HSE publications:

Controlling Noise at Work, Guidance on Regulations, L108, ISBN 0 7176 6164 4

Noise at Work (leaflet), INDG362(rev1), ISBN 0 7176 6165 2.