Noise

Introduction

The Control of Noise at Work Regulations 2005 apply to all places of work and require employers to carry out assessments of the noise level and take appropriate preventive action where necessary.

Noise can damage a person's hearing, causes stress and can contribute to accidents by causing communication difficulties. The Control of Noise at Work Regulations require action to be taken where noise exceeds prescribed levels of:

• Daily noise of exposure of 80dB(A) (lower action value) & 85dB(A) (upper action value);
• Peak noise action values of 135 dB(C) (lower action value) and 137 dB(C) (upper action value); and
• Noise exposure limits of 87dB(A) and 140dB(C).

The designer should attempt to eliminate noisy equipment and noisy processes from the design.

The employer/contractor should attempt to eliminate the noise or contain the noise by acoustic cladding, enclosures, etc. before resorting to the supply of hearing protection.

If a prescribed operation necessary for the construction process exceeds these levels it should be clearly specified in the Pre-Tender and Construction Health and Safety Plans.

Those affected

Under the regulations employers are required to safeguard both their own employees and other workers not employed by them who are exposed to noise caused by their activities.

Action and Limit Values

The Control of Vibration at Work Regulations specify Exposure Action Values (EAV) and Exposure Limit Values (ELV).

Noise lower exposure action values

• a daily or weekly personal noise exposure of 80 dB (A-weighted); and
• a peak sound pressure of 135 dB (C-weighted).

Noise upper exposure action values

• a daily or weekly personal noise exposure of 85 dB (A-weighted); and
• a peak sound pressure of 137 dB (C-weighted).

Noise exposure limit values

• a daily or weekly personal noise exposure of 87 dB (A-weighted); and
• a peak sound pressure of 140 dB (C-weighted).

Where the exposure of an employee to noise varies markedly from day to day, an employer may use weekly personal noise exposure in place of daily personal noise exposure for the purpose of compliance with the Regulations.

In applying the exposure limit values, but not in applying the lower and upper exposure action values, account shall be taken of the protection given to the employee by any personal hearing protectors provided by the employer in accordance with regulation 7(2). (Without prejudice to the provisions of regulation 6, if an employer is unable by other means to reduce the levels of noise to which an employee is likely to be exposed to below an upper exposure action value, he shall provide personal hearing protectors to any employee who is so exposed)

The exposure action values are the levels of exposure to noise at which you are required to take certain actions. The exposure limit values are the levels of noise above which an employee may not be exposed to. Your risk assessment should include an assessment of the likely noise exposure of your employees for comparison with these exposure action and exposure limit values. A formula for calculating daily exposure is shown in 1 Part 1 and for peak sound pressure in Schedule 2 to the Control of Noise at Work Regulations.

Weekly exposure

Regulation 4(4) allows you to calculate exposures over a week rather than over a day in circumstances where noise exposure varies markedly from day to day. The formula for calculating weekly exposure is shown in Schedule 1 Part 2 to the Noise Regulations.

Use of weekly exposure might be appropriate in situations where noise exposure varies markedly from day to day, e.g. where people use noisy power tools on one day in the week but not on others. It is only likely to be appropriate where daily noise exposure on one or two working days in a week is at least 5 dB higher than the other days, or the working week comprises three or fewer days of exposure.

When considering whether to use weekly averaging it is important to:

• ensure there is no increase in risk to health. It would not, for example, be acceptable to expose workers to very high noise levels on a single day without providing them with hearing protection. There is an overriding requirement to reduce risk to as low a level as is reasonably practicable;
• consult the workers concerned and their safety or employee representatives on whether weekly averaging is appropriate;
• explain to workers the purpose and possible effects of weekly averaging.

Taking account of hearing protection

Note that the requirements in the Control of Noise at Work Regulations relating to assessment of risk and exposure, actions to take to reduce risk and exposure, and the levels at which they are required to be taken, do not allow you to take account of the reduction of noise provided by wearing hearing protection.

Regulation 4(5) explains that the only exception when this reduction can be taken into account is in relation to the exposure limit values. The reduction is likely to be an estimate based on the information provided by the manufacturer of the particular hearing protection device used. Whether the exposure limit values are complied with will depend, not only on the reduction provided by the hearing protectors, but also on whether the hearing protection is in good working order, is appropriate for the type of noise and is properly worn.

In any event employers have a duty to reduce the risk of noise related hearing damage to the lowest level reasonably practical.

Protective Measures

There are 4 main ways of limiting or controlling noise:

• Reduction of the noise at source
• Isolation of the source of the noise
• Hearing protection for workers at risk of exposure
• Reduction of the exposure time

All possible means should be used to control noise at source. However, should it prove impossible or impracticable to reduce noise levels sufficiently, then it is necessary to provide persons at risk with some form of hearing protection.

Protective Equipment

Hearing protection equipment is simple and inexpensive and its use in areas of high noise may prevent hearing impairment. There are three forms generally available:

• Ear plugs.
• Ear muffs.
• Helmets.

Each form of protection has its own characteristics but all should be comfortable and safe to use, not produce a toxic reaction in the wearer, not impair vision or speech communication and provide the proper level of noise attenuation.

Noise Reduction

Attempts should be made to reduce noise by use of the following means:

• Can the work be done in another way which does not involve the use of noisy equipment?
• If this is not possible can a quieter item of equipment be used?
• When buying or hiring equipment choose the quietest model available.
• Try and carry out noisy jobs well away from other workers or move workers away whilst noisy operations are being carried out.
• Try and reduce the noise at source by fitting mufflers to breakers, drills etc.
• Keep covers closed on compressors, most modern ones are designed to run with the covers closed even in hot weather.
• Ensure the exhausts of compressors generators and other plant are directed away from work areas and place screens faced with sound absorbent material around plant. It is possible to use spoil heaps or materials stores as sound barriers around noisy plant.

Such measures can prove to be very effective if carried out and maintained.

Health Surveillance

Health surveillance must be provided for all employees who are likely to be regularly exposed above the upper exposure action values, or are at risk for any reason, e.g. they already suffer from hearing loss or are particularly sensitive to noise.

The purpose of health surveillance is to:

• warn the employer when employees might be suffering from early signs of noise damage;
• give the employer an opportunity to do something to prevent the damage getting worse;
• check that control measures are working.

The employer should consult with trade union safety representative, or employee representative and the employees concerned before introducing health surveillance. It is important that the employees understand that the aim of health surveillance is to protect their hearing.

The employer will need the employees' understanding and co-operation if health surveillance is to be effective.

Health surveillance for hearing damage usually means:

• regular hearing checks in controlled conditions (audiometric);
• telling employees about the results of their hearing checks;
• keeping health records;
• ensuring employees are examined by a doctor where hearing damage is identified.

Ideally health surveillance should commence before people are exposed to noise (i.e. for new starters or those changing jobs), to give a baseline. It can, however, be introduced at any time for employees already exposed to noise. This would be followed by a regular series of checks, usually annually for the first two years of employment and then at three-yearly intervals (although this may need to be more frequent if any problem with hearing is detected or where the risk of hearing damage is high). series of checks, usually annually for the first two years.

The hearing checks need to be carried out by someone who has the appropriate training. The whole health surveillance programme needs to be under the control of an occupational health professional (for example a doctor or a nurse with appropriate training and experience). You, as the employer, have the responsibility for making sure the health surveillance is carried out properly.

Information Sources

• The Building Research Establishment has a helpful web site and a help sheet: 'Improving Sound Insulation in Homes'.
• The Association of Noise Consultants will give you a list of accredited acoustic experts.

Local Authorities

Particular measures may be required depending on the location of the works. The local authority may impose restrictions on work days or hours and / or on noise levels where the work is adjacent to hospitals or residential homes for example.