Hand Arm Vibration
Hand arm vibration is vibration transmitted into the hands and arms when using handheld powered work equipment. Regular users of handheld or hand-guided power tools and machines are at risk. Workers holding work-pieces which vibrate while being processed by powered machinery such as pedestal grinders are also at risk.
Hand Arm Vibration Syndrome (HAVS) affects the nerves, blood vessels, muscles and joints of the hand, wrist and arm. It includes vibration white finger (VWF), which can cause severe pain in the affected fingers. HAVS can also cause carpal tunnel syndrome – a nerve disorder which may involve pain, tingling, numbness and weakness in parts of the hand.
Risk factors:
- Frequency of the vibration – 2 to 1,500 Hz is potentially damaging, 5 to 20 Hz is most dangerous
- Magnitude of the energy measured in m/s2
- Strength of the grip and other forces necessary to hold or guide the tool or work-piece
- Duration of exposure
- Frequency of exposure
- Low temperature
- Individual factors, e.g. smoking, susceptibility to vibration energy, age, health and general well-being
Exposure Action Value (EAV), above which employers are required to act to control exposure:
- 2.5 m/s2 A(8)
Exposure Limit Value (ELV), which is the maximum amount of vibration an employee may be exposed to on any single day:
- 5 m/s2 A(8)
Controls:
- Eliminate the need for a worker to hold vibrating equipment, e.g. automate a process
- Minimise the required force or grip on the tool or work piece
- Provide suitable low vibration tools
- Ensure the right tool is used for each job
- Ensure tools have been properly maintained to avoid increased vibration caused by faults or general wear, and keep cutting tools sharp so that they remain efficient
- Reduce the amount of time vibrating tools are used (work scheduling / job rotation / rest breaks)
- Use of dose monitors / limiters
- Keep workers warm and dry (provide gloves, a hat, waterproofs and heating pads if required)
- Provide workers with information and training on the risks and precautions
Whole Body Vibration (WBV)
Whole-body vibration is the shaking or jolting of the human body through a supporting surface (usually a seat or the floor), e.g. when driving or riding a vehicle along an unmade road.
Regular operators and drivers of off-road machinery e.g. construction, mining and quarrying machines and vehicles, tractors and other agricultural and forestry machinery.
Some short-term symptoms are back pain, abdominal pain or general feeling of discomfort, including headaches, chest pain, nausea and loss of balance. Some long-term symptoms are disc displacement, degenerative spinal changes, lumbar scoliosis, degenerative disorders of the spine and disorders of the gastrointestinal system.
The HSE view is that WBV is unlikely on its own to cause back pain but can aggravate a back problem caused by another activity, e.g. a muscle strain caused by an accident
The risk factors are unusually high vibration or jolting or the vibration is uncomfortable for a long time on most working days
Exposure Action Value (EAV), above which employers are required to take action to control exposure:
- 0.5 m/s2 A(8)
Exposure Limit Value (ELV), which is the maximum amount of vibration an employee may be exposed to on any single day:
- 1.15 m/s2 A(8)
Controls:
- Select vehicles and machines with the appropriate size, power and capacity for the work and the ground conditions
- Maintain vehicle suspension systems correctly (e.g. cab, tyre pressures, seat suspension)
- Make sure that paved surfaces or site roadways are well maintained, e.g. potholes filled in, ridges levelled, rubble removed
- Train and instruct operators and drivers to be able to adjust seat positioning and driver weight setting on suspension seats