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Noise is defined as "unwanted sound" and in the workplace, is produced by a wide variety of activities, plant, machinery and equipment. In situations where this exceeds 85db(A), it is necessary to make assessments of employees daily exposure levels. Where these exceed the ''action levels'' contained within current regulations, action to control exposure to noise must be taken. This document is intended to provide guidance on preventing hearing damage and complying with legal requirements.
Levels of noise in excess of 85dB(A) can cause irreversible hearing damage. When people are exposed to high noise levels for even short periods, they may experience temporary hearing loss, but after returning to a normal environment, this soon recovers. However, when employees are exposed to high noise levels every working day for many years, they slowly develop a permanent hearing loss. It is a cumulative process that worsens with time and its affects may not be appreciated until years later. The risks become greater with both increases in sound level and the time spent in a noisy environment. Some very high levels of impulsive noise, lasting only a fraction of a second, can cause instantaneous damage.
High levels of noise can also have other effects on employees and has been shown to increase stress, blood pressure and tiredness. It can also cause other psychological effects, interfere with communication and reduce the efficiency of those exposed.
Employers must identify noisy areas, take measurements, make assessments and then carry out a programme of work that will depend on the level of exposure, or ''action level'' to reduce noise exposure.
Current regulations require employers to identify noisy activities and areas where employees are likely to be exposed to levels of noise above 85 dB(A). Three action levels are specified:
Employers must also keep records of assessments, provide ear protection, where required, identify hearing protection zones, and reduce noise at source where the second action level is exceeded.
As a rough guide, any area where it is difficult to hold a conversation without raising voices, or where it is necessary to shout to someone at a distance of about 2 metres, should be investigated more thoroughly.
Where a potential problem has been identified, measurements of noise using a suitable, properly calibrated, sound level meter must be made to accurately determine the problem that exists.
Assessments of "peak" pressure are most likely to be needed where workers are exposed to loud noises from exploding sources (e.g. cartridge tools). Care must be taken when measuring peak levels because many sound level meters are not capable of measuring this value. Meters with only a "Fast" or "Impulse" capability do not have a quick enough response to accommodate measurements of "peak" levels.
The purpose of the assessment is to:
The person undertaking the assessment must be competent.
Assessments will have to be reviewed whenever changes occur. These may include:
Although there may not have been any obvious changes, workplaces should be checked at least every two years. Levels can creep upwards without being noticed e.g. as the result of machine wear.
Suitable records of assessments should be kept. These will include details of the workplaces, areas or jobs assessed and what the results were and when the assessments were made.
In addition it is advisable to:
Exposure Level between 85-90 dB(A)
It is not compulsory to wear ear protection when exposure is between the first and second action levels but is compulsory to:
Exposure Level above 90 dB(A) or a Peak of 200 pascals
Ear protection is compulsory when the exposure exceeds the second action level of 90 dB(A) or the peak action level of 200 pascals. In addition, it is also necessary for the employer to:
Where noise levels have the potential to cause injury, reasonable steps should be taken to reduce the noise to the lowest practical level. The following measures form the hierarchy of noise control:
Choosing a Suitable Type of Protector
Any hearing protection issued should be adequate enough to provide sufficient attenuation to maintain values below the second and peak action levels. It should be of a suitable fit and be compatible with any other protective equipment or special clothing that is worn.
Individuals differ in what they find comfortable and should preferably be given a choice.
Equipment provided should remain personal and not be passed from one person to another. For hygiene reasons, ear plugs should not be issued to persons who are subject to ear infections.
Areas where the second or peak action levels are exceeded must be designated hearing protection zones. These zones should be clearly demarcated and the entrances to the zone marked with appropriate safety signs i.e. blue circular mandatory signs with relevant pictogram.
No employee should be permitted to enter a hearing protection zone without wearing hearing protection. Where it is not practical to mark hearing protection zones, for example, where noise sources are portable and are moved to different locations, it would be necessary to make alternative arrangements. This could include attaching signs to tools, warning that protectors must be worn when used, or by giving written instructions designating particular tasks or operations as ones where protectors must be used.
All equipment used for noise protection should be maintained.
These should be maintained in a clean, serviceable condition and kept in a clean locker or cupboard when not in use. They should be regularly examined for damage.
Where disposable protectors are used, dispensers should be topped up regularly to ensure that supplies are continuously available. Re-useable plugs should be kept in a clean storage place when not in use.
Silencers or noise enclosures that are provided as control measures must be maintained in a good condition. Spot checks should be made to monitor their effectiveness.
Designers, manufacturers, importers and suppliers of plant and machinery for use at work have a legal obligation to provide articles that are safe and without risks to health and to provide information needed for their safe use, including information on noise emission.
Information should therefore be obtained on noise emitted by machinery, plant or equipment, prior to its purchase.
These duties also mean that if a machine is likely to produce noise capable of harming health, action will need to be taken to:
Current regulations require all employees subject to the 85 dB(A) exposure level to be provided with information, instruction and training.
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