Hand-arm vibration (HAV) is the vibration that is transmitted from a work process into the workers’ hands and arms. This can be caused by operating hand-held power tools, hand-guided equipment, or by holding materials that are processed by machines.
Several studies have shown that frequent as well as regular exposure to HAV can result in permanent adverse health effects. These are most likely to occur when contact with a vibrating tool or work process is a frequent and significant part of an individual’s job. Hand-arm vibration can cause a lot of conditions collectively known as hand-arm vibration syndrome or HAVS.
The three main components of HAVS
1. Peripheral neuropathy of the hands that produce tingling, numbness or both in a glove distribution. Also, there may be a loss of dexterity.
2. Secondary Raynaud’s phenomenon of the hands, seldom referred to as vibration white finger (VWF). This is the most dramatic manifestation, producing intermittent blanching of the fingers starting at the distal tip of one or more digits. Furthermore, as the disease progresses, the pallor extends more proximately to involve the length of the fingers, sometimes extending into the palm. However, the thumbs are the least affected.
3. Musculoskeletal problems. These are the least distinct manifestations and can include complaints of discomfort, weakness and pain in the hands, wrists, forearms as well as elbows.
Raynaud’s phenomenon and peripheral neuropathy may occur independently but usually happen together. Symptoms tend to be bilateral, and it is unusual for more advanced symptoms to affect only a single digit. In such a case, other diagnoses such as hammer syndrome, as well as the vascular injury of the palmar arches or digital arteries, should be considered.
Conditions such as bone cysts and carpal tunnel syndrome, changes of the elbows, wrist, and hand are associated with exposure to hand-arm vibration. Still, it is difficult to separate the contribution of vibration to these conditions from the ergonomic risk factors commonly encountered with hand-held power tool usages. Some of them are forceful static postures, prolonged awkward postures, repetitive movements, as well as trauma.
Types of hand-held power tools and equipment
- hand-held grinders
- impulse tools
- powered lawn mowers
- ratchet screwdrivers
- concrete breakers
- cut-off saws
- hammer drills
- impact wrenches
- pedestal grinders
- brush/weed cutters
- power hammers
- power chisels
- powered sanders
Miners, fallers, buckers, glaziers as well as auto mechanics are the industrial groups most commonly diagnosed with HAVS. The main risk factor for HAVS is a combined exposure of thousands of hours of intense vibration from tools such as grinders, chainsaws, jackhammers and impact tools. Contributing risk factors include smoking, age and pre-existing medical conditions that lead to neuromuscular pathology.
Doctors should consider the diagnosis of HAVS for any of their patients who complain of peripheral neuropathy or Raynaud’s phenomenon of the hands and also, who use power tools on a regular basis in the workplace. An occupational medicine specialist assesses all the HAVS claims. Once the diagnosis is confirmed, there is an evaluation for workers for a permanent functional impairment based on the severity of symptoms and signs of their disease. Those with more advanced disorders are always advised to stop work with hand-held power tools. Those with an undue risk of impairment may be eligible for rehabilitation.
Those who have mild diseases and workers who choose to continue working with hand-held power tools should reduce exposure to hand-arm vibration as much as possible. This can be done by using low-vibration tools, wearing vibration-reducing gloves as well as adjusting work schedules to reduce the duration of the exposure. Such workers should be monitored regularly for the progression of their disease.
Possible controls to eliminate or reduce HAVS risk exposure
- Train operators/ staff to avoid unnecessary exposure to vibration hazards.
- If possible, increase the productivity of the present device to reduce exposure time.
- Consider changing to other tools or equipment, which can perform the same job with less exposure to vibration hazards. The crucial thing is to look for equipment or devices that produce less vibration or that can do the same job faster. Furthermore, the power-to-weight ratio should be as high as possible.
- Use and purchase tools with optimal ergonomic design. This includes an optimal angle of the main handle, an excellent grip comfort as well as a small distance between the support handle and the front of the device, if used in a horizontal orientation.
- Check the air installation to ensure proper pressure and flow.
- Make sure that you are using the most effective tool for the task performed.
- Use job rotation to decrease exposure time.
- Change the design of the product to decrease the need for tasks involving exposure to vibration, or change the process entirely to get rid of the vibrating task.