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Noise control in the workplace. Protect Your Employees

Hearing protection matters

What is noise

A subjective definition of noise could be ‘unwanted sound’. What is noise to one person is just entertainment to another. Ask two persons of different ages what they think about Rap music, for instance.

From a scientific perspective, noise is a series of pressure waves.

From a legal standpoint the definition of noise is different: the best practice exposure level is 85 db for all workers averaged over an eight hour period.

The decibel scale is a logarithmic scale, which means that the scale is not linear, and we really have a hard time relating to the numbers. For example, an increase in the noise level of 10 db means a tenfold increase in the actual noise level.

Inside the ear

Noise erodes the small hair cells inside the cochlea of the human hearing organ. It is normally a very gradual process, and not a very noticeable one in the early stages. The damage that occurs on a daily basis is at first only temporary hearing loss. With repeated noise exposure the temporary damage turns into a permanent damage. At this stage the damage is irreversible.

How can you prevent this from happening to you or your employees?

Noise control measures should come first. Get rid of the noise whenever possible. When all measures have been taken to improve the environment, so far as is reasonably practicable, then we should consider hearing protection.

An average ear muff or ear plug will reduce noise on average by about 20 to 29 db. Considering that every 3 db cuts the noise in half, you can get a lot of protection from an ear muff or ear plug. But hearing protection has to be used correctly or it will lose a great proportion of its effectiveness.

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“the best practice noise exposure level is 85 db for all workers averaged over an eight hour period”

The louder the noise, the more damage it can cause, and much of it? could be long term damage. We need to address what measures are to be taken to reduce the risk of exposure, in turn preventing long term damage to the employees.

By contrast, some damage can be caused immediately, when people are exposed to peak sound waves produced by loud noises such as explosions or cartridge-operated tools.

Anyone can be exposed to excessive noise levels. However, those working in noisy workplaces, factories, foundries, working with power tools, plant and machinery, and in noisy environments such as construction sites are among those most at risk.

What do employers need to do?

It is the obligation of the employer to ensure that every effort has been made to protect staff at risk of noise in the workplace. General Health and Safety legislation covers all employers and workplaces - specifically, the Control of Noise at Work Regulations 2005 in the UK, which are a good source of guidelines in the absence of local law.

These regulations require employers to take action if daily or weekly exposure to noise is at, or in excess of certain Exposure Action Levels.

These are the specific steps an employer is recommended to follow in order to protect their staff:

  • Conduct a Noise Assessment. This assessment should cover both loudness, {db (A)} and frequency, {Hz} in order to plan the correct controls
  • Take steps to prevent or control the risks. For example engineering controls through design and layout of the workplace. Implementing procedural controls for the employees affected by the noise can also reduce risk, e.g. only allowing the minimum number of essential staff into the effected area
  • Where possible, eliminate exposure to noise at the source by changing the process or equipment
  • Control exposure to noise - limiting time/duration of exposure by changing the process for the affected employees
  • Provide Personal Protective Equipment (PPE) - consultation with your PPE supplier will quickly show that there are noise protection solutions for virtually all work situations
  • Provide information and training to educate the workforce as to the danger and required precautions
  • Regularly monitor and review the effectiveness of the measures - for example by measurement of noise levels and conducting health surveillance on those identified as being at significant risk from the noise problem

The Exposure Action Levels are referenced in the Regulations in decibels (db).

  • The lower exposure action value is termed as daily or weekly personal noise exposure of 80db (A), or a peak sound pressure/impact noise of 135db (C)
  • The upper exposure action value is daily or weekly personal noise exposure of 85db (A), or a peak sound pressure/impact of 137db (C)

There is always an upper limit of exposure and there are levels of noise that must not be exceeded. These are called Exposure Limit Values and take into account reductions provided by hearing protection:

  • Daily or weekly exposure of 87db (A)
  • Peak action level - peak sound pressure/impact of 140db (C)

There is a general rule (the ‘two metre rule’) which can be used to simplify this and to put it into context. For example, the noise level is about 85db (A) if people have to raise their voices to be heard at a distance of about two metres from the source of the noise.

“noise erodes the small hair cells inside the cochlea of the human hearing organ. The damage that occurs on a daily basis is at first only temporary hearing loss. With repeated noise exposure the damage turns permanent”

Once a noise assessment has been completed this should not just be filed away. The noise assessment is just the start of the process, not the end. They should be used to assist the employer to carry out their duties to reduce the risk of hearing loss and control noise exposure.

At the Lower Action Values, employers should:

  • Assess the noise exposure
  • Eliminate noise exposure at source or reduce to a minimum level
  • Provide information, instruction and training on risks and how to minimise risk, including how they can obtain hearing protection, if the workers wish to use it
  • Ensure that all necessary maintenance is carried out to hearing protection and equipment

At the Upper Action Values, employers must do all the above and also:

  • Mark hearing protection zones with prominent notices
  • Provide everyone exposed with suitable hearing protection and ensure that it is wornSafe place versus safe person

Safe Place versus safe person

Employers must first try to eliminate or reduce noise in the workplace by means other than hearing protection. PPE should only be considered as a last resort and even then selected carefully.

All hearing protection is relatively poor at low frequency noise reduction, but certain models which are specifically designed for this type of noise are far better than non-specialised hearing protection.

As with all control strategies, we should consider making the? workplace safe before we start to look at handing pieces of safety equipment on to the workforce, the so-called safe place strategy being preferable to the safe person strategy.

In all workplaces, it may be worth considering the design and layout of the premises. Perhaps there could be a designated area, away from the noise, in which the affected staff could take their breaks, ensuring that they have a complete rest from the exposure.

The length of time that employees are exposed to such levels of noise is just as important as the volume itself. It is worth encouraging staff to take regular breaks and to spend time in designated quiet areas.

Quite often, noise control requires more than one solution, as noise will be produced from a number of sources.

Good practices

Reducing and eliminating sources of noise

There are many ways to reduce noise levels which are outlined below. A good guideline would be first to introduce methods and practices which protect the maximum number of the exposed staff.

These may include:

  • Careful selection of equipment to ensure it is the quietest available. This will mean introducing a low-noise purchasing policy for new equipment
  • Implementing a quieter way or process of doing the work
  • Improving maintenance procedures - good maintenance can reduce noise from friction and moving parts
  • Fitting silencers to exhausts
  • Isolating or damping vibrating machinery by fitting anti-vibration mounts
  • Adding sound absorbing material to vibrating panels to reduce vibration
  • Enclosing noisy machinery in acoustic booths
  • Erecting barriers and screens around noisy machinery and processes
  • Positioning noisy machinery and processes well away from workers
  • Using sound absorbing materials to reduce reflection of sound within buildings
  • Limiting access by keeping people out of noisy areas
  • Limiting time spent in noisy areas

PPE - Hearing protection

Hearing protection should only be considered as a temporary measure, or as a last resort where a risk remains after steps have been taken to reduce noise levels. PPE should not be seen as a quick fix for a serious risk. It is not an alternative to controlling noise by technical and organisational means, but for tackling the immediate risk while other control measures are being developed.

“there are many ways to reduce noise levels, a good guideline would be first to introduce methods and practices which protect the maximum number of the exposed staff”

In the longer term, it should be used in tandem with technical and organisational changes and can even provide additional protection beyond what has been achieved through noise control.

Protective equipment should be made available to employees where they are exposed to levels of noise.

Where noise exposure exceeds the upper action value, employers should:

  • Provide hearing protection to everyone exposed, and ensure it is used
  • Identify Hearing Protection Zones with signs to show where hearing protection must be worn
  • Provide information, instruction and training on how to use and take care of hearing protection
  • Make sure that hearing protection is properly maintained

Choosing the right type of hearing protection

Ensuring that the right type of hearing protection is used is vital in the process. There are two main types - those which cover the ear and those which are inserted into the ear.

The Noise Assessment should indicate which sort of equipment is the most suitable for the circumstances. The reduction of noise when using these different types of equipment varies. As a rough guide, in-ear plugs can reduce the noise level by 10-15 db (A) and ear muffs which cover the ear can reduce noise levels by 20-25 db (A), provided that they are fitted correctly.

Of course, account must be taken of the frequency as well as the ‘loudness’ when considering which protective equipment is the most appropriate solution.

This is an important factor, as not all types of equipment are suitable or offer the correct level of protection for every type of noise. For full guidance and advice, a specialist PPE supplier must be consulted.

When supplying hearing protection, it is the responsibility of the employer to ensure that the equipment is compatible with other types of equipment already in use by the employee. Regular checks to ensure that the equipment is being used correctly, and that the equipment is in good working condition should also be a priority of the employer.

Important factors to consider in the selection and use of hearing protection include:

  • Types of protector, and suitability for the work being carried out
  • Noise reduction offered by the protector, including taking account of ‘real-world’ factors, and also ensuring that not too much protection is provided, so the worker is now isolated from what is happening around them
  • Compatibility with other safety equipment
  • Pattern of the noise exposure
  • The need to communicate and hear warning sound
  • Environmental factors such as heat, humidity, dust and dirt
  • Cost of maintenance or replacement
  • Comfort and user preference
  • Medical conditions the wearer may have

Selection of the type

Ear muffs and banded ear plugs are especially recommended in cases where the hearing protection must be taken off frequently due to repeated short term noise exposure, in cases where the user has narrow ear canals and in cases of inflammation of the ear canal.

Ear plugs are recommended at workplaces with continuous noise, in case of extreme sweating under ear muffs, in case of simultaneous wearing of spectacles, goggles or if other personal protective equipment is worn. Ear plugs can be reusable or disposable. The reusable type must be kept scrupulously clean to avoid ear infections.

Banded ear plugs are suitable in changing and less high noise situations, where they must be worn and taken off frequently. They shouldn’t be worn if sound pressure peaks can occur due to contact of the band - at a welder’s screen, for example.

"hearing checks should be conducted by a competent person where employees are regularly exposed to noise levels above the action values"

Custom moulded ear plugs are individually fitted, offer a high level of wearer’s comfort and a high level of safety if the function (fitting) is checked when the plugs are delivered, and after that at regular intervals. They are often used if the worker has the beginnings of hearing damage, to ensure a reliable sound attenuation.

Ear muffs and ear plugs with electro-acoustical equipment (level dependent hearing protection) are good to use in intermittent noise situations in the workplace if a good speech perception is required.

Communication ear muffs or ear plugs can promote or allow communication in noisy areas.

Ear-muffs with integrated entertainment facilities like FM radio are suitable particularly for workplaces with monotonous tasks in noisy areas. A check for the intelligibility of warning signals at the work place is necessary in each case.

What do employees need to do?

Once the employer has taken their responsibility for assessing and providing appropriate equipment, the employee also needs to comply. For example, employees must take all reasonable steps to ensure that any protective equipment used is returned to the accommodation provided for it after use. This applies unless the employee removes the equipment from the workplace. Examples of this type of equipment could include footwear or clothing.

The employee should also examine any safety equipment before use to spot any loss or obvious defect, which of course must be immediately reported to their supervisor. Importantly, the employee should not be carrying out any sort of maintenance of the equipment, unless trained and authorised to do so.

Employees should not intentionally vandalise the equipment provided - this is a particular problem associated with the use of ear muffs in hot weather, such as the summer months in the Gulf, which can result in workers drilling ventilation holes in the muffs.

Hearing checks (health surveillance)

Office workers are encouraged to have eyesight checks if they are using display screen equipment regularly and are deemed to be at significant risk. Similar guidelines can transfer to workplaces affected by noise. Rather than eyesight checks, hearing checks.

These should be carried out if there is a risk that noise levels could damage hearing. This will warn of any employees who may be suffering from early symptoms of hearing loss. It also allows employers to check that noise controls are adequate and update the levels of protection accordingly.

Best practice states that health surveillance be implemented for all workers at or above the Upper Exposure Action Value.

Hearing checks should be conducted by a competent person where employees are regularly exposed to noise levels above the action values. Once the employer has a baseline figure for each employee it is important that regular checks are conducted on their hearing. The interval between hearing checks will depend on a number of factors, including the level of risk and whether the checks show that hearing loss is evident.

In order to establish a start point or datum, it is good practice to carry out hearing checks for new employees in noisy workplaces. Such datum can be used to monitor any possible future loss or hearing ability.

Training

Good noise management all comes down to training, which is the most vitally important component in health and safety. This should include ongoing training to existing staff and introductory training for new starters. A designated member of each team should be responsible for communicating to the rest, perhaps via regular tool box talks.

If equipment is used to protect staff, this needs to be done consistently and correctly across the board, with regular checks for adequacy, cleanliness and use.

Reviewing how the changes have affected staff needs to be regularly completed. This will be an indication of how well the noise controls put into place are working. Spot checks of equipment in usage and checks of the noise levels will demonstrate how effective these implementations have been and demonstrate management commitment.

In summary, noise can be harmful, either causing short term or acute damage from excessively high levels of exposure to impact noise, or more commonly by progressive harm caused by regular exposure to much lower noise levels.

As mentioned above, we should always try to make the workplace as safe as we can before we consider making the worker as safe as possible, by using PPE or other similar controls.

When specifying personal protective equipment as the solution to a noise problem, always consult the specialist suppliers to ensure the best solution in terms of both loudness, db and frequency, HZ.

Published: 01st Apr 2011 in Health and Safety International

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Pat McLoughlin has more than 27 years experience in health and safety, developed after a practical grounding of 10 years in Engineering at Land Rover. He was with ROSPA for six years before forming British Safety Services in the Sultanate of Oman, with his bus...
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