Thursday, 17 December 2009

Noise: just a nuisance or damaging to your health?

Noise can be a nuisance affecting your concentration and causing you to get annoyed, i.e. noisy neighbours, roadworks or passing vehicles; disrupting your relaxation, reading, watching the television or sleep. However noise, particularly in the work-place, can actually have a severe impact on your health, causing temporary or permanent damage to your hearing. Also, working in high levels of noise can impact general safety, by interfering with communications particularly safety warnings for example fire alarms.

Under the regulations of the HSE Noise Regulations 2005 there is a duty for employers to protect the hearing of their workers.

A risk assessment must be carried out to determine the levels and duration of noise. Action must be taken to reduce the exposure to noise by choosing quieter equipment and machinery, installing noise dampening insulation wherever possible or provide different types of hearing protection.

The noise must be assessed using the following criteria:

• Is the noise intrusive i.e. similar level to a busy street, a vacuum cleaner or a crowded restaurant for most of the working day?
• Do your employees have to raise their voices to carry out conversation when approximately 2 metres apart for at least part of the day?
• Are your employees engaged in using or being in close proximity to noisy powered tools or machinery for more than 30 minutes in a day?
• Is your industry noisy, i.e. construction, demolition, road repair, textiles, engineering, forging, pressing, bottling, canning or paper manufacture?
• Are their impact noises; hammering, drop forging, pneumatic drilling or explosive sources such as cartridge operated tools, detonations or guns?

How is noise measured?

The measurement unit for noise is decibels (dB). An ‘A-weighting’ ‘dB(A)’ is used to measure average noise levels and a ‘C-weighting’ ‘dB(C) measures peak, impact or explosive noises.
A 3dB increase in noise level is generally noticeable but in fact doubles the noise level, therefore relatively small differences in the numbers can be significant.

Typical Noise Levels

Action Levels and Limit Values

Certain actions must be taken when the levels of exposure are averaged over a working day or working week and also the maximum noise (peak sound pressure) to which employees are exposed to in a working day.

There are two values:
• Lower exposure action values
o Daily or weekly exposure of 80dB
o Peak sound pressure of 135dB
• Upper exposure action values
o Daily or weekly exposure of 85dB
o Peak sound pressure of 137dB

There are also levels of noise that must not be exceeded
• Exposure limit values
o Daily or weekly exposure of 87dB
o Peak sound pressure of 140dB

Reducing noise levels

There are ways of reducing noise levels and exposure, redesigning the workplace and the work patterns can be useful.

• Use quieter processes and equipment
o Can you do work in some other quieter way?
o Can you replace whatever is causing the noise with something less noisy?
o Introduce a low-noise purchasing policy for machinery and equipment
• Introduce engineering controls
o Avoid metal on metal impacts e.g. line impact points with rubber or reduce drop heights
o Dampen vibration on machine panels
o Use anti vibration mounts or flexible couplings
o Fit silencers to exhausts and nozzles
• Modify the paths by which noise travels through the air
o Erect enclosures around machines
o Use barriers or screens to block the direct path of sound
o Position noise sources further away from workers
• Design and layout the workplace to reduce noise emission
o Use absorptive materials within the building to reduce sound reflection i.e. open cell foam or mineral wool
o Keep noisy machinery away from quiet areas
o Design the workflow to keep noisy machinery out of highly populated areas
• Limit the time spent in noisy areas
o Halving the time in a noisy area will reduce noise exposure by 3dB
• Maintain the machinery
o Have a planned maintenance schedule
o Replace worn parts immediately

Hearing Protection

If the noise levels cannot be reduced to a level that is acceptable then hearing protection must be issued to employees. Once issued it is mandatory to ensure that they are used properly. Hearing protection zones must be indentified and clearly marked. The employees must be trained and given information on how to use them and care for them.

There are some do’s and don’ts listed below:

• Make sure that the protectors give enough protection – aim to reduce levels to 85dB at the ear
• Target the use of protectors to noisy tasks in a working day
• Select protectors that are suitable for the environment in which they are being used – consider how comfortable and hygienic they are
• Think about how they will be worn and interact with other protective equipment (hard hats, respiratory protection and eye protection
• Provide a range of protectors so that employees have a choice on what is suitable for themselves.

• Provide protectors that cut out too much sound – this can cause isolation or lead to an unwillingness to wear them.
• Make the use of hearing protectors compulsory where the law does not require it.
• Have a blanket approach to the use of hearing protection - it is better to target its use to where it is needed.

There are different items that can be used for hearing protection:

Ear plugs are inserted to block the ear canal. They may be pre-moulded (preformed) or mouldable (foam ear plugs). Ear plugs are sold as disposable products or reusable plugs. Custom moulded ear plugs are also available.

Semi-insert ear plugs which consist of two ear plugs held over the ends of the ear canal by a rigid headband.

Ear muffs consist of sound-attenuating material and soft ear cushions that fit around the ear and hard outer cups. They are held together by a head band.
Different levels of protection are available it is important that you choose the correct level.

All hearing protection should comply to the following EN Standards:

EN352-1 Muffs and Headband
The section of the standard deals with head fasteners and establishes requirements in terms of manufacture, design and performance, test methods, instructions relating to marking and information intended for users.

EN352-2 Plugs and Bands
This part of the standard also deals with individually moulded ear plugs and devices connected by bands

EN352-3 Muffs and Helmet mounted
The present section of the standard stipulates requirements in terms of manufacture, design and performance, test methods, instructions relating to head fastener marking and information intended for head fastener users, when the latter are fixed on protective industrial helmets.

Ranges of hearing protection products including Peltor and Sordin brands are available on the Granite Workwear website under Ear Protection and Forestry Tools and Accessories; they offer various levels of protection covering all uses.

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