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September 21, 2008

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HAVS risk assessment guide

David Wilson explains how to conduct a risk assessment for Hand Arm Vibration Syndrome from  the perspective of a power-tool purchaser, and stresses the importance of maintaining tool appendages in the fight against HAVS and related illnesses.

Hand-arm vibration affects thousands of UK workers each year, and causes both short and long-term medical afflictions, such as carpal tunnel syndrome and vibration white finger, known collectively as hand-arm vibration syndrome (HAVS).

HAVSAccording to the HSE, there are up to 5 million workers using hand-held or hand-guided power tools in the UK, with 2 million of these exposed to levels of vibration that could result in ill health.1 Industries where workers are most at risk include construction, rail, mining, maintenance, estate management, public utilities, manufacturing, and engineering. HAVS may manifest itself as: loss of strength in the hands; inability to, or reduced, grip; and numbness in the fingers, especially in the tips. HAVS sufferers can also end up with painful joints and permanent damage to bones in their hands and arms.

Mitigating the risks of vibration exposure requires careful management, effective training, and a good dose of common sense. There is a number of factors that employers must consider, in order to comply with the law and provide a safe system of work — not to mention so they can be confident they are in a position to successfully defend any potential claims for compensation from employees working with tools.

The Control of Vibration at Work Regulations 2005 set an Exposure Action Value (EAV) — the daily amount of occupational exposure a machine user can absorb, above which employers are required to take action — and an Exposure Limit Value (ELV), which must not be exceeded. Employers must also now identify the vector sum for tools on the market with different appendages in typical site-based materials. This can be done by accessing actual working figures from organisations that are independent of manufacturers, such as the Industrial Noise and Vibration Centre, or the Off-Highway Plant and Equipment Research Centre (OPERC) (see pp 59-60) for more explanation). Such ‘real-life’ data means that tools used on site have been tested outside of simulated factory settings, which is important, as how many end-users use equipment in sterile test conditions?

Users must also be able to differentiate between tools that are best for productivity versus those with the lowest possible HAV ratings — as an item of equipment that records a lower vibration impact could, in fact, lead to increased overall exposure for the user if the task takes twice as long.

So, when buying or hiring new tools, try to find equipment with the lowest vibration but also with a good performance rating. Think about who will use it, and what they need to know in terms of how long they can use it for, and the best way of holding it while in use, as this can affect the vibration emissions. Trade associations and government bodies are useful resources for non-partisan information.

HAVS Risk Assessment: The questions to ask

Before any HAV work is undertaken, as with any manual work, a risk assessment must be performed by a competent person. That person will investigate the task at hand and provide answers to such questions as:

* Does this work need to be done?

* What equipment will be required?

* Is the nominated person qualified to use the equipment?

* What are the hazards? and

* How can any foreseeable risks be eliminated and/or reduced in severity or likelihood?

The risk assessment may factor in the following:

* Duration of exposure and frequency are determinants for HAV measurement and output. Any vibration frequency from 1—1500Hz is potentially hazardous, becoming increasingly more so if the frequency reduces to 1—50Hz. This, combined with the period of time for which the item is in use, determines the amount of exposure the user receives;

* Frequency of exposure — is the equipment used hourly/daily/

weekly? Remember: exposure is measured by trigger time, not how long users may be working on a job in total;

* The force of contact — how hard does the user have to grip, or how much pressure must they exert on the equipment?

* Circulation — is the working temperature warm enough? If not, do workers need protective clothing or gloves to help keep hands warm and blood circulating? Remember, also, that smoking affects circulation.

For both employers’ and employees’ records, risk assessments must be recorded and filed, as well as revised if workers’ job descriptions change significantly.

Further considerations

The Control of Vibration at Work Regulations 2005 highlight several other considerations that must form part of any HAV risk assessment. These include:

* The magnitude, type and duration of exposure;

* Effects of vibration on the workplace and equipment, including proper handling of controls;

* Information supplied by the equipment manufacturer;

* The availability of replacement equipment to reduce vibration exposure — or, alternatively, ongoing maintenance to ensure vibration effects remain low;

* Any extension of exposure at the workplace to whole-body vibration beyond normal hours;

* Any specific working conditions, such as low temperatures; and

* Health-surveillance information.

It should also go without saying that training is necessary for anyone using powered equipment. Operators should understand the health effects of HAV, as well as the risks; how to calculate their EAV allowance; and the measures that must be taken to minimise vibration exposure. Training will also help inform workers of the importance of equipment selection, how to maintain it, and how to record its usage. Once new or improved working habits have been planned, introduced, and successfully implemented, it is critical that they are adhered to, and regularly reviewed, so that any previous bad habits do not resurface.

Controlling exposure to HAVS

Once a risk assessment has been completed, it is absolutely essential to act on any areas of concern, always returning to the key question: does this job require vibrating equipment? If the answer is yes, then procedures must be taken immediately to control risk.

One way to minimise exposure to vibration is to rotate jobs among users, and factor this in to any project-management timeframe. After all, one person with one drill will not break up a football pitch’s worth of concrete in a day, so make sure you plan ahead. Ideally, there will be a number of trained people available to use vibrating equipment, especially if the job is particularly labour-intensive, in order to limit the amount of time employees are exposed to vibration. Remember, however, that exposure will not be limited if operatives simply move from using one powered item to another, i.e. switching from a drill hammer to a breaker does not minimise HAV exposure.

Exposure figures must also be gauged against the individual and the tasks they are carrying out. While the OPERC database figures may give fairly accurate measurements, a consideration of personal factors, such as the operator’s technique and physical strength, and the material being processed, will help determine where exposure can be controlled and minimised.

Impaired efficiency

Using properly maintained equipment from reputable suppliers, as well as holding the equipment properly, and for the specified safe amount of time, are all critical factors. After all, the correct application of all the manufacturer’s and trainer’s advice becomes redundant if auxiliary items are left to deteriorate.

The subject of appendage maintenance is rarely talked about in health and safety circles. One reason for this could be that it is perceived as a given, i.e. everyone does it and, therefore, industry professionals choose not to comment on it.

From the sheer number of worn-down tools I see on an all-too-regular basis, this is not necessarily the case. On the contrary, I believe it has been passed over as a niche vibration-related subject because the effects of poorly-maintained tools are less obvious. Everyone can see, for example, when a petrol-breaker needs fixing because it might not start on the first, second, or third attempt. However, it is not so clear with worn tools and, for those who don’t know any better, they may not think they could cause any adverse effects. This could not be further from the truth.

A new tool appendage loses condition after its very first use. Blunt and eroded tools are prone to increasing the amount of vibration absorbed by the user significantly, as they produce more friction and impair efficiency, as the task takes longer to complete. The result for employers is that their risk-assessment data, which has been gained from using new equipment, becomes distorted.

In short, you can complete all the necessary risk assessments, complete all the training, and have in place excellent health-surveillance processes, but if you don’t maintain the tools, and especially the drill bits and appendages, people will still be left vulnerable to risk.

Data distortion

It is also important to remember that most of the current published data on HAV levels has been obtained when using tools at optimum condition. Blunt tools can also get hotter at the core, and stresses can lead to cracking in the tool. Worn-down appendages, such as chisels, drill bits, or blades, can significantly increase the reverberations from powered equipment, which render any previous EAV calculations inaccurate.

The fall-back is that increased emissions brought about by using blunt tools may be picked up through your health-surveillance programme, but, by then, it could be too late. So, starting a job with a sharp, good-quality tool is absolutely paramount, as is using appendages that have been correctly sharpened and tempered. For drill bits, make sure that they are diamond or carbide-tipped, and, when using saws, good-quality cutting discs must always be used.

If professional tool maintenance isn’t possible within the company, invest in a well-respected maintenance channel partner, who will re-sharpen tools to the correct angles.

Any professional tool-maintenance company will carry out the following procedures:

* heat and re-forge the tools back to their original specification; and

* harden and then re-temper the tool in an oil-quench bath.

It should also go without saying that any new appendages must be those recommended by the manufacturer, and that reconditioning must be carried out in conjunction with the manufacturer’s guidelines.

Remember, also, that keeping appendages well maintained is the job of both the employer and the employee. Employers must keep records of how regularly they recondition appendages, while employees should alert their supervisors when their tools start to become worn. Employers should also provide their employees with extra appendages so they can change them when they start to lose their edge.


Tool maintenance is an important, albeit highly-specific, area in the fight against HAVS-related health problems. Sharper, precision-cut tools are more effective and reduce the amount of vibration the operator is exposed to, so appendage maintenance should be factored in to all risk assessments and equipment overhauls.

Ideally, an appendage maintenance programme should be implemented by all UK companies. More people who work in those industries at most risk from vibration emissions need to stand up and take note. By doing so, employers will increase productivity, protect their workers, and protect themselves from days lost at work due to illness and compensation claims.

Engineering firm failed to properly assess vibration risk

A Hampshire engineering firm has been fined £10,500 for failing to protect a worker from exposure to vibration in the workplace between March 2003 and March 2006.

Aldershot Magistrates’ Court heard how Tews Engineering Ltd employed Bill Leonard to remove surplus metal from a thick metal profile using a hand-held grinder.

In May 2005, just after he began complaining of pains in his hands and difficulty in gripping the grinder, his job title was changed to deburrer/sawyer, but his daily tasks remained largely unchanged.

After he was diagnosed with hand-arm vibration syndrome (HAVS) and realised the gravity of his problems, Leonard complained to the HSE about having to use vibrating tools excessively at the profiles department at Tews’ premises in Petersfield.

Ray Kelly, the HSE inspector who investigated and prosecuted the case, told SHP that the problem had been building up over a period of three years: “During the first two years of his employment, there was no assessment of the risks Leonard was exposed to at all, but most of the damage was done during this time. It should have been done before he started work, not two years in.”

Kelly went on to say that a general vibration risk assessment for the department did not go far enough in assessing how much vibration Leonard was being exposed to, and for how long. The firm introduced some very simple control measures, such as anti-vibration gloves and changing his grinding wheel to a flap wheel, made from softer material, but the damage had already been done.

Leonard is unlikely to work again, as he has irrevocably lost the strength of his grip, as well as his dexterity. He has periods of complete numbness and permanently painful hands.

On 6 August this year, Tews Engineering pleaded guilty to contravening s2(1) of the HSWA 1974 by failing to protect the health of employees; and reg.3(1) of The Management of Health & Safety at Work Regulations 1999 for failing to carry out a proper risk assessment. The company was fined £8500 for the first offence and £2000 for the second, plus costs of £10,500.



David Wilson is group health, safety, environment & quality manager for HSS Hire.


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15 years ago

Vibration white finger
the vibration white finger is the injury from which lots of workers are suffering….one of my frnd use to work in the rail track construction… he suffered the same disease… the fault was in the tools he was using….