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May 28, 2018
Maintenance managers and health and safety executives that learn to protect their workers from Hand Arm Vibration Syndrome (HAVS) will increase the company productivity, profits and reputation.
Does your organization perform intensive jobs such as shut downs in oil and petrochemical refineries, assembling large pipe elements into a liquid or gas pipeline, or tightening metallic structures in buildings and infrastructure?
Do operators use vibrating hand tools such as grinders or impact wrenches for long periods in a day, day-in, day-out, all year as shown in the table below? Do operators sometimes complain about numbness or white fingers after using hand tools, or pains in their hand after temperature change?
If so, then workers are at risk of HAVS and it’s time to take action before it’s too late.
The Hand Arm Vibration Syndrome is recognized as a serious work-related disorder, which is affecting thousands of industrial workers. It is represented by damage to blood vessels, nerves, muscles and joints of the wrist and arm caused by intensive and repeated vibration exposure. This exposure comes from working with vibrating tools or holding shaking materials. The repeated hits on the fingers and hands at certain frequencies constitute a risk for the workers. There is no certainty about how this happens exactly, but numerous studies show damage to the very fine blood vessels in the hands as one probable contributor to the syndrome.
• Early symptoms: Repeated loss of feeling, numbness, in the fingertips and sensation of needles in the fingers, tingling, are early indicators. These sensations can come and go and are not proof of HAVS, but should be seen as early warnings.
• Later symptoms: Later, more severe symptoms are often felt like permanent numbness of fingers, causing difficulties in daily life when handling small objects or when buttoning for example.
When getting cold or wet, the fingers will often react by becoming white, then red while being painful. This is called the Raynaud's phenomenon, and is also common in hand arm vibration syndrome cases.
All frequent users of power tools that vibrate during usage could be affected. Vibration level and trigger time per work shift are the key factors that together give an indication if the person is at risk. According to a Japanese long-term study on forest workers using chainsaws (Nagoya, 1994), there is a strong relation between the number of years of exposure and the prevalence of HAVS. Among the workers over 50 years of age, 38% showed signs of this syndrome. US National Safety Council estimates that about 2 million U.S. workers are exposed to hand-arm vibration today, and as many as half could develop HAVS (read full article). HAVS is preventable, but once the damage is done, it is often permanent.
Many measures can be taken to reduce risk. Limiting time of vibration exposure being clearly the most important one, some other key points can be taken into account to protect yourself, your colleagues or your employees:
There are two things to consider to identify if workers are at risk: the tool’s level of vibration and the time of exposure.
| Vibration Magnitude, m/s² | Daily exposure action value: If reached, technical and organizational actions must be taken to reduce vibration exposure |
Daily exposure limit value: Should never be exceeded |
| 2.5 | 8 hours | >24 hours |
| 5 | 2 hours | 8 hours |
| 10 | 30 minutes | 2 hours |
| 15 | 13 minutes | 53 minutes |
| 20 | 8 minutes | 30 minutes |
It’s worth noting that manufacturer values of vibration magnitude are indicative only and they should always be measured in the application’s real conditions. This may not always be possible, and if this is the case then a safety coefficient multiplier should be applied to the manufacturer’s value and Standard ISO5349 referred to for further information on measuring the vibration level.
Let’s take a look at Joe’s situation:
According to the Directive, for a vibration of 15 m/s², the action value is at 13 minutes. Since Joe’s tool has a slightly lower vibration than that, there is no risk. There is a larger margin to the limit value, which he would reach after about one hour.
However, if the situation was to change and he was required to loosen many more bolts per shift, he would be at risk of exceeding the action value and the employer would need to take steps to reduce this. Some examples might be:
In operations with vibration exposure, prioritize best practices by ensuring all employees use safety equipment, maintain tools properly, and keep hands warm to prevent injuries.
Disclaimer: This article is neither a magnum opus control exposure to hand-arm vibration nor legal advice for your company to use in complying with your local regulations. Instead, it provides background information to help you better understand how to address some important points. This information is not the same as legal advice, where an attorney applies the law to your specific circumstances, so we insist that you consult an attorney if you’d like advice on your interpretation of this information or its accuracy. In a nutshell, you may not rely on this paper as legal advice, nor as a recommendation of any particular legal understanding.
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