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Hearing Protection

Published: 10th Mar 2011 in OSA Magazine

David Whiting discusses how a strategic risk assessment approach can work best in noisy workplaces.

Setting the scene

It has been known for many years that exposure to sudden loud noises such as gunshots or explosions can cause hearing loss. However, most cases of deafness at work arise from long term exposure to relatively low levels that cause irreparable damage to the cilea, hair cells in the cochlea, which transmit vibrations to the brain.

Current understanding suggests that in general employers, employees, and suppliers do not always engage in good practice for noise control, despite there being plentiful information and advice available on this issue. In addition, evidence suggests a widely held belief that the problem of noise is ‘solved’ with the issuing of personal hearing protection, and that ‘engineering’ noise control is difficult and/or expensive.

There are various factors that may influence the behaviour of employers in managing risks from noise, including behavioural and other human factors, barriers to:

• Uptake of technical / organisational noise control measures

• Use of low noise / low exposure tools/machines

• Appropriate use of hearing protection

• Provision of health surveillance

Legal requirements

While different countries may lay different emphases on Noise at Work Regulations, they all require an employer to control the exposure of their employees to excessive noise levels based on a formal hazard identification and risk assessment process.

There are many differing ways in how this can be achieved and advice varied from my research from one country only having a few pages of documentation
requirements (no red tape there), to well documented and resourced back up facilities. These findings shape the rest of this article.

Most countries have established mandatory action levels ranging from 80 dBa to 85 dBa.

Health considerations

New research now suggests that workplace noise affects heart disease. The National Health and Nutrition Examination Survey 1999-2004 suggested that a persistently noisy workplace more than doubles an employee’s risk of serious heart disease and concludes in the report: “This study suggests that excess noise exposure in the workplace is an important occupational health issue and deserves special attention.”

Various other media articles tell us about teenagers losing their hearing at ear-splitting rock concerts, machinists developing hearing loss from constant exposure to loud noise, people going deaf after an explosion or workers affected because they often work around noisy vehicles and power equipment – and hearing damage also happens on the job when workers are exposed to less intense, but sustained noise over time.

Can you answer ‘yes’ to any of these questions about the noise where you work:

• Is the noise intrusive – like a busy street or a crowded restaurant – for most of the working day?

• Do you raise your voice to have a normal conversation 2m apart for at least part of the day?

• Do you use noisy powered tools or machinery for more than half an hour a day?

• Do you work in a noisy industry, e.g. construction, demolition or road repair; woodworking, plastics processing, engineering, textile manufacture, general fabrication, forging, pressing or stamping, paper or board making, canning or bottling, foundries?

• Are there noises because of impacts (e.g. hammering, drop forging, pneumatic impact tools), explosive sources such as cartridge-operated tools or detonators, or guns?

Effects of exposure to loud noise

Managing noise in the workplace to minimise the risk of damage to employees’ hearing can be a time-consuming task, particularly in large organisations with
myriad sites and working practices. Here’s why it’s worth careful consideration:

• Exposure to loud noise will inevitably cause hearing loss over time

• Loud noise damages or destroys the nerves in the inner ear

• Another effect can be tinnitus, or permanent ringing in the ear

• Once the nerves of the inner ear are destroyed or damaged it is permanent

When is noise too loud?

Noise is measured in units called decibels or dB.

• If two people three feet apart must shout to be heard, the background noise is too loud

• Noise above 140 decibels causes pain and immediate hearing loss

• People with some hearing loss will have difficulty hearing at lower levels of background noise

Long term exposure to noise

• Our ears can recover from short exposure to loud noise, but over time nerve damage will occur

• The longer and louder the noise, the greater chance permanent damage will occur

• People who say they are “used to the noise” often have already lost some of their hearing

Hearing loss from noise exposure

• Exposure is usually not noticed because it is so gradual

• Speech includes higher pitches such as in the letter “s”

• Often the first noticeable effect is difficulty in hearing speech

• Hearing aids only partially help people with severe hearing loss

Tinnitus from noise exposure

• Exposure to high noise levels can also cause permanent ringing in the ear, or tinnitus

• Tinnitus sufferers usually complain of constant whistling, squealing, roaring or buzzing in one or both ears

• Severe tinnitus may disrupt sleep, reduce concentration and cause irritability and depression

Advice on managing tinnitus issued

Tinnitus causes ringing in the ears or head, with the noise generated within the body rather than coming from an external source. The level can range from a light buzzing to a constant roar of sound. It can often be caused by working conditions, particularly among those working with noisy industrial equipment, or in call centres.

Not enough is known about this very complex condition and a lot of research is still ongoing for finding treatments and cures, as well as to keep sufferers up to date on the latest information available. Industry needs to recognise that noise levels cannot be controlled with the use of hearing protection alone, while many employers will also consider further measures to bring down noise exposure to much lower levels as either cost prohibitive, or technically problematic.

The role of hearing protection

Logically, if there is a responsibility to reduce the risk caused by noise exposure and it turns out that persistent noise well below the level of 80dB (A) does indeed present a risk of heart disease, and then surely there is a direct duty to significantly reduce levels well below current best practice.

An added complication is that, according to the guidance regulations, “protectors that reduce the level at the ear to below 70dB should be avoided.” This may sound contradictory to the requirement to reduce noise to as low a level as practical, but hearing protection that provides too high a protection value can ‘mask’ other sounds, such as warnings and alarms.

However, before even thinking of reducing noise to much lower levels, it is essential that companies begin by implementing a hearing conservation programme, as this will form the foundations of any future noise-reduction efforts.

Risk assessment

Assessing the risk of injury to an employee from noise means working out how much noise they are being exposed to – it is as simple as that.

All regulations state the levels of exposure that are known to cause problems but, if there are potential health risks at levels below these thresholds, it is even more important to know what levels workers are exposed to in practice, so that any reductions can be quantified in consideration of all the risks posed by the noise. It is also true that employers may struggle to defend a compensation claim for noise-induced hearing loss without actual measurements in the workplace.

Mistakes

During the course of my research I discovered two mistakes consistently made when reviewing workplace noiseat- work assessments.

The first concerns the measurement position.

Without proper training, there is a strong temptation for employers to produce noise maps as a means of carrying out risk assessment. Noise maps are simply a plan of a workplace with noise levels shown at various points and sometimes with contour lines joining levels of equal loudness together, the idea being to show what noise levels are at any given place in a site.

For risk assessment, measurements should only ever be taken at the operator’s head position at their places of work; noise maps have no place in this process and should only be used if there is a specific need – for example, in noise control when mapping out noise-activated signage.

A second consistent mistake was a lack of understanding what the action values actually mean in practice.

If the noise level is well above 80 or 85dB, but the time spent in that area is only short such that the exposure is below 80dB, then the worker will not exceed the legal exposure level. A further complication is that an employee may work on two or more different processes in one eight hour period.

Noise control

The idea that control is the way to deal with noise in the workplace is implicit in the title of the legislation, and this is also backed up by the fact that hearing
protection must only be considered as a ‘last resort’ measure. Furthermore, it is now suggested that hearing protection alone cannot protect against certain non hearing-related risks associated with noise at work.

Basic safety actions to adopt

Below are some ideas which can yield significant results or others which should be treated with caution:

• Absorption – It’s a lovely thought to put special materials on the walls to ‘absorb’ noise but, in truth, it is rather wishful thinking, as the results will be limited compared with the cost of installation. Absorption has a part to play in a control programme, but should only be used on the advice of a noise-control expert.

• Enclosures – A lot of focus is often put on enclosing machinery to reduce the noise. This can be a very expensive operation and can result in other problems linked to ventilation, ease of access, and ongoing maintenance. For some machinery, enclosures may be the only solution but, once again, these should be specified and installed under professional guidance.

• Air noise – This is an area where major noise-reduction improvements can be made for minimal input. Employers should ensure, among similar actions, which leaks are controlled, low-noise nozzles on blowing lines are being used, and exhaust filters are all working properly. However, it is important that
these measures are kept up to ensure their effectiveness.

• Engineering and maintenance – Well maintained machinery makes less noise, so reducing the inherent noise a machine or process emits will require an engineering approach. Very often, there is a lot that can be done by someone who knows what they are looking for, and this can often be enough to avoid the use of enclosures and absorption methods.

Health surveillance

It is important to remember that there will only ever be a small number of people in any organisation who are truly at risk of suffering noise-induced hearing loss.

Such people may simply be more susceptible to hearing damage. Alternatively, they might not wear hearing protection properly, or they might just be exposed to noise more than anyone realised.

Finding out who among their workforce are at heightened risk will require employers to carry out health surveillance for noise-induced hearing loss, which really amounts to one thing – hearing tests.

Questionnaires and interviews will form part of a comprehensive testing programme, together with audiometry. As well as a person who is competent to conduct the audiometry tests, companies will also need a system for dealing with any results that highlight a potential problem.

Measuring worker exposure

It can be very difficult to measure exposure to noise and the damage it does. Workers in some industries are exposed to noise at varying volumes and durations in an inconsistent pattern throughout the working day. In this instance measuring and assessing is not as straightforward as it would be in a factory. Things can become difficult for the safety practitioner when cases of noise-induced hearing loss (NIHL) are diagnosed and, while the hearing loss
appears to be occupationally related, all the information from the workplace suggests there is no noise over exposure.

A question you must want to ask is what is ‘standard’ working day? What would it look like and how many different kind of exposures could I be exposed to?
That’s why you may need to think about a dosemeter.

How big is the problem?

Occupational Health Practitioners suggest that some hearing loss is a common characteristic and it is now accepted; however, that loss of hearing may result from a single exposure to a very brief impulse noise or explosion – but such traumatic losses are rare.

Make sure your noise and hearing protection training includes:

• The effects of noise on hearing (including both occupational and non-occupational exposures)

• Noise controls used in your workplace

• The purpose of hearing protectors

• The advantages, disadvantages, and attenuation of various types

• Instructions about selecting, fitting, using, and caring for hearing protection

• The purpose and procedures for programme evaluation including audiometric testing and hearing protection auditing when you choose to rely upon auditing

• The employees’ right to access records kept by the employer

• Maintain a written programme describing initial and refresher training

It’s a life cycle thing

Hearing conservation should be viewed as a circular process, in which all the parts highlighted above are interdependent. Surprisingly, there are many companies that don’t have a fully functional line of communication between health and safety and occupational health. The results of audiometric testing should trigger specific assessments, which, in turn, should guide the process of control and the use of PPE.

Other causes

There are two other possible mechanisms to consider with regard to causes of hearing damage.

• Chemical damage – The possible interaction between noise and chemicals is worth deeper examination, especially as many studies of health associate
hearing loss with noise, and pulmonary and cardiac dysfunction with exposure to fire smoke and related toxins.

Currently the combined effect that exposure to chemicals and noise will have on hearing remains poorly understood, and the increase in manufactured
products and nanotechnology has increased the range of chemical exposure appears to enhance the effect noise has on hearing; the focus therefore should
remain on controlling noise exposure.

• Exposure – The second and third mechanisms suggested could be found in any environment where the pattern of noise exposure is inconsistent. However, they are a direct challenge to the principle of equal energy: the direct relationship between the sound pressure level (SPL) and exposure duration.

An examination into a normal working day can identify a number of noise sources and tasks that have a wide variation both in SPL and exposure duration – and this creates a multi-dimensional problem that is difficult to resolve.

Assessing the damage

Consider making a pragmatic approach to assessing noise exposure, which takes into account the potentially disproportional effect high-frequency or short-duration noise episodes might have on hearing and rather than trying to assess noise in relation to a reference eight-hour working day, assess each activity and its potential contribution towards the total daily noise dose.

Effectively set a maximum fractional noise dose that an activity can contribute to an individual’s daily noise dose, either by actual measurement or estimate of exposure.

Should this be exceeded, action must be taken. Any limit would need to be reasonably low; a level of 30 percent of the upper exposure limit action value is suggested as the point for intervention.

Control measures

To develop controls for noise exposure in these circumstances, engineering measures should always be attempted first, but the difficulty is that for the bulk of the working day, hearing protection is not necessary.

Management will have to assess not only the activities that will require measures to control them, but also who will require protection. In some cases it may be just the operator of a noisy tool; in other circumstances all workers in the vicinity will require protection.

Any hearing protection would have to incorporate some form of voice attenuation and this often reduces the protection to the wearer, and means noise levels might not be reduced below the suggested 30 percent threshold, and any debate will have to focus on whether protection from most noise sources is sufficient, if only some protection is afforded against others.

• If control measures can take the ‘edge’ off noise during actual operations, will rigid enforcement of hearing protection measures during training activities be enough to prevent hearing loss?

• Will taking these measures meet the spirit of the law, so far as is reasonably practicable, in circumstances where there is an imperative to act in order to save life and property?

• Finally, will this approach afford sufficient protection to prevent permanent damage?

Unpredictability and work-flow

In any industry generally, the eight hour reference period for noise assessment may only be of use where there are standard working practices that can be measured and assessed against a predictable and repeatable working day.In circumstances where this cannot be achieved, a standard reference period might just be concealing a problem.

Conclusion

In an ideal world it would be possible to establish with confidence the daily or weekly personal noise exposures for each and every member of staff to help target noise-control resources.

The strategies outlined above have been successfully employed by many major organisations and it is hoped that the implementation of similar strategies,
where appropriate, could allow others to avoid the pitfalls identified, and promote a robust and expeditious programme of hearing conservation. 

References:

BMJ-British Medical Journal: Persistently noisy workplace more than doubles heart disease risk

HSE Reducing Noise at Work – Guidance on the Noise at Work Regulations 1989 (L108)

HSE Behavioural & people’s attitudes to wearing hearing protection and how these might be changed

World Health Organisation: Quantifying burden of disease from environmental noise: 2nd report.

World Health Organisation: Prevention of noise-induced hearing loss

Author Details:

David Whiting is the Operations Director of Safety Business Services (SBS) Ltd. Their mantra is “SBS developing Best Practice.” David has been an instigator in Occupational Health and Safety and Risk Management, working with different lead bodies in setting and developing the change agenda.

His presentations and training are energetic, interactive and seminars and workshops have instilled confidence in countless people around the world.

Clients have stated:

• “In short, he helps people exceed their goals and has helped many of us to understand that removing a hazard altogether is better than trying to control it.” (UAE Trainee)

• “The real brilliance of his work is that it is so simple – and that’s what good safety ultimately is.” (Californian delegate)

• “David has this ability to connect and inspire at all levels, his quote “Accidents hurt in many ways - safety doesn’t cost the same” set the tone of the debate. (MEP)

David was recently quoted by a CEO in his annual report as saying: 

“We all have a responsibility to challenge and learn from past practice - we cannot simply accept the status quo and live with it. What we can achieve is to take a more pragmatic approach, addressing things as we find them and seeking to improve them in practical ways, but also bearing in mind the risk and not overdoing it.”

David Whiting, EurOSHM, CMIOSH, MIIRSM, OSHCR, AIEMA, MIFL, is registered to operate in both Europe and internationally. David has led the SBS consultant practice with more than 35 years of occupational health, safety and risk management experience, working with both private and public sector environments. His particular  area of expertise is the implementation of management systems, with experience in developing or delivering training programmes, courses covering general safety management or specific topics, across a broad range of industries.

Currently he is working with Rolls Royce as their Global Resourcing and Development Advisor.

W: http://www.sbs-associates.

E: davwhiting@uwclub.net

www.osedirectory/health-and-safety.php

Published: 10th Mar 2011 in OSA Magazine

Author


David Whiting


David Whiting, Safety Business Services (SBS) Ltd

David Whiting has been an instigator in change in Health and Safety presentations and training. His energetic, interactive seminars and workshops have instilled confidence in countless people around the world. In short, he helps people exceed their goals.

As a charted member of the Institute of Health and Safety (IOSH), and Company Director of Safety Business Services (SBS) Ltd, are a associate consultant service with over 35 years of occupational health, safety, corporate governance, contingency planning, supply chain and risk management experience working in both private and public sector environments.

Particular area of expertise is the implementation of management systems with experience in developing or delivering training programmes, courses covering general safety and risk management or specific topics, across a broad range of industries.

David and his associates are proud to be working in Partnership with IMS Certification FZE and National Academy and can be contacted on their stand at the Intersec trade fair.


David Whiting

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