Hand arm vibration syndrome (HAVS)
Introduction
Direct mechanical energies applied to the body can cause serious harm.
- Thus relatively high frequency waves conducted through the air i.e. noise, can cause noise induced hearing loss
- Relatively lower frequencies conducted through solids (vibration) in close contact with the body can transmit their energy to the body and also cause harm. Usually vibration is transmitted through the hand and arm and could cause Hand Arm Vibration Syndrome (HAVS)
- The lowest range of frequencies usually apply to the body as a whole and can cause problems such as motion sickness
This page will give an introduction to Hand Arm Vibration Syndrome - a range of symptoms and signs, which in the past has included terms such as Vibration White Finger (VWF). Hand-arm vibration is vibration transmitted into the hands and arms when using hand-held powered work equipment. Too much exposure to hand-arm vibration can cause hand-arm vibration syndrome (HAVS) and carpal tunnel syndrome. HAVS can be responsible for substantial physical impairment, disability, handicap and distress. The extent of this has only been widely accepted relatively recently.
Other exposures may contribute to increasing the likelihood and/or severity of HAVS - these include cold and tobacco smoking.
Clinical manifestations
The clinical manifestations consist generally of two main aspects:
- Vascular - HAVS affects the nerves, blood vessels, muscles and joints of the hand, wrist and arm. It can become severely disabling if ignored. It includes vibration white finger (a blanching of the fingers) which can cause severe pain in the affected fingers, especially after exposure to cold and with delayed/poor recovery thereafter. There are similarities between these manifestations and Raynaud's disease
- Neurological - Carpal tunnel syndrome is a nerve disorder which may involve pain, tingling, numbness and weakness in parts of the hand, as well as the associated objective neurological sensory deficits. It can be caused by, among other things, exposure to vibration
There may be other manifestations related to the above, e.g. damage to bone and muscle. Dupuytren's contracture (usually affects one of the flexor tendons of the ring finger) might also be the consequence of cumulative trauma to the palm of the hand.
Early signs and symptoms
- Tingling and numbness in the fingers (which can cause sleep disturbance)
- Inability to feel things with the fingers
- Loss of strength in the hands ( may be less able to pick up or hold heavy objects)
- In the cold and wet, the tips of the fingers going white then red and being painful on recovery (vibration white finger)
Continuing to use high-vibration tools will worsen the symptoms, for example:
- The numbness in the hands could become permanent and result in total loss of feeling
- Difficulty picking up small objects such as screws or nails
- The vibration white finger could happen more frequently and affect more fingers
Who is at risk?
Anyone regularly using hand-held or hand-guided power tools and machines such as:
- Concrete breakers or concrete pokers
- Sanders, grinders or disc cutters
- Hammer drills
- Chipping hammers
- Chainsaws, brush cutters, hedge trimmers or powered mowers
- Scabblers or needle guns
Also at risk are workers holding workpieces which vibrate while being processed by powered machinery, such as pedestal grinders.
Legal duties
The Control of Vibration at Work Regulations (2005) require an employer to:
- Assess the vibration risk to employees
- Decide if they are likely to be exposed above the daily exposure action value (EAV) and if they are:
- Introduce a programme of controls to eliminate risk, or reduce exposure to as low a level as is reasonably practicable
- Provide health surveillance (regular health checks) to those employees who continue to be regularly exposed above the action value or otherwise continue to be at risk
- Decide if they are likely to be exposed above the daily exposure limit value (ELV) and if they are:
- Take immediate action to reduce their exposure below the limit value
- Provide information and training to employees on health risks and the actions being taken to control those risks
- Consult the trade union safety representative or employee representative on proposals to control risk and to provide health surveillance
- Keep a record of risk assessment and control actions
- Keep health records for employees under health surveillance
- Review and update the risk assessment regularly
Exposure action value (EAV) and exposure limit value (ELV)
What is the exposure action value?
The exposure action value (EAV) is a daily amount of vibration exposure above which employers are required to take action to control exposure. The greater the exposure level, the greater the risk and the more action employers will need to take to reduce the risk. For hand-arm vibration, the EAV is a daily exposure of 2.5 m/s2 A(8).
What is the exposure limit value?
The exposure limit value (ELV) is the maximum amount of vibration an employee may be exposed to on any single day. For hand-arm vibration, the ELV is a daily exposure of 5 m/s2 A(8). It represents a high risk above which employees should not be exposed.
Further information on HAVS, including health surveillance and prevention, can be found at the Health and Safety Executive website.