Repeated and excessive contact with vibrating tools, equipment and materials will over time cause symptoms of ill-health known as HAVS or VWF (vibration white finger). These affect nerves, joints, muscles, blood vessels or connective tissues of the hand and forearm.
The symptoms may be:
· A tingling whiteness or numbness in the fingers affecting nerves and blood vessels. Initially the symptoms may be hardly noticeable and in mild cases affect only the tips of the fingers. But as the condition develops the whole finger down to the knuckles may become white. Feeling may also be lost.
· Fingers change colour as the blood vessels are affected. With continued exposure periodic attacks may occur in which the fingers turn white or blue when exposed to cold or vibration. Initially the fingers rapidly become pale and feeling is lost. After warming up or at an indeterminate time blood circulation will resume and the fingers may show an intense red flush. This phase is often associated with uncomfortable throbbing, pins and needles and sometimes acute pain.
· In more severe forms there may be a loss of dexterity. Attacks may occur frequently in cold weather, both at work and during leisure activities, such as gardening, car washing and watching outdoor sports. Theyl may last for up to an hour causing considerable, loss of dexterity and reduced grip.
The effect of vibration is cumulative. When symptoms first appear, they may disappear after a short time. If exposure to vibration continues over months or years, the symptoms worsen and become permanent.
The Health and Safety Executive (HSE) estimates that around five million workers in the UK are exposed to hand-arm vibration in the workplace. Around 40% of those exposed, 2 million workers, are exposed to levels of vibration where there are clear risks of developing disease.
It’s not all gloom and doom though – HAVS is preventable. But once damage is done it is permanent and the costs to employees and to employers of inaction could be high. In many cases employees who have developed work related symptoms have claimed damages from their employers, receiving on average £20,000 per successful claim
In 2002, in response to a European Directive requiring action to reduce the risks of exposure to excessive vibration at work the UK introduced The Control of Vibration at Work Regulations 2005. The regulations introduced action and limit values for hand-arm vibration, (similar to the approach to the control of noise) and require action if these values are reached or exceeded:
· Exposure Action Value (EAV) of 2.5m/s2 averaged over 8 working hours is the level at which employers should introduce technical and organisational measures to reduce exposure.
· Exposure Limit Value (ELV) of 5.0m/s2 averaged over 8 working hours is the level which should not be exceeded.
The Regulations are designed to protect against risks to health and safety from hand-arm vibration syndrome (HAVS), and from carpal tunnel syndrome in people exposed to vibration, and in situations where vibration might affect a person’s ability to safely handle controls or read indicators, or where it might interfere with the stability or security of structures.
They require employers to manage the risks from exposure to HAV when measured against the Exposure Action and Exposure Limit values. Inevitably this means that risk assessment is required and the first step is to consider whether work activities involve exposure to vibration. If they do the exposure levels must be measured or calculated.
To assess the daily exposure to vibration of a worker (or a group of workers doing similar work) it is necessary to know:
· Which tasks expose them to vibration.
· What equipment they use.
· What they use it for.
· The total time they are in contact with the equipment while it is operating – often referred to as ‘trigger time’.
To be relevant, the vibration information you use in your vibration assessment needs to match as closely as possible the likely vibration performance of the equipment you plan to use in the way you plan to use it. This can be quite an easy task where the exposure is due to the use of hand held tools and equipment. The suppliers technical information should include details of vibration exposure to the operator and this will be of help. But remember that these measurements are of new equipment in laboratory conditions; they can understate in use exposure by as much as 50%.
There are however web-based databases, including www.vibration.db.umu.se/HavSok.aspx?lang=en (sponsored by the EU) and http://www.operc.com/pages/havteclogin.asp which give measurements for a wide range of tools by manufacturer and model. This level of detail is important because the vibration created by portable tools can vary between make and model; hammer drills, for example, range between 6 m/s2 to 18 m/s2.
Where the exposure to vibration is through contact with a workpiece or other fixed equipment there will be little alternative to measuring an employee’s actual exposure through the working day. An accelerometer is used for the purpose.
Where exposure is at or above the Exposure Limit or Action Value the work process needs to be modified or adapted to reduce exposure. Actions that will succesfully reduce exposure will be explained in the next edition of Bottom Line Express.
Because the effects of exposure are irreversible and cumulative employers are also required to provide health surveillance for those likely to be exposed to vibration at or above the action level. Ideally health surveillance should be provided at lower levels too because some employees with existing health problems may be susceptible to lower levels of HAV. In every case it is vital to recognise and respond to early signs of damage.
The HSE recommends a simple approach to health surveillance. Their system starts at a level that can be delivered and checked in house escalating to formal medical consultations where the initial in-house assessments indicate a potential or real health problem. It links the level of surveillance required to the level of risk and will be cost effective. This tiered system works as follows:
· Tiers 1 & 2 – short questionnaires used as a first check for people moving into jobs involving exposure to vibration, and then annually for employees exposed to vibration risks. Analysis of these replies will show either that no further action is required or that a Tier 3 assessment is required.
· Tier 3 – an assessment by an occupational health nurse or similarly qualified person. If the assessment shows that the employee has HAVS Tier 4 will apply.
· Tier 4 – a formal diagnosis carried out by a doctor qualified in occupational health. The doctor will advise on the employees fitness for work.
· Tier 5 is optional and involves referral of the employee for specific tests for HAVS. The results may help the doctor assess fitness for work.
Note that the HSE recommends that an employee exposed to HAV should have a Tier 3 assessment once every 3 years even where Tiers 1 and 2 assessments reveal no problems. This provides an opportunity to identify symptoms that may not have been revealed in the tier 1 or 2 checks.