5.2 Vibration

Effects on the body

There are two types of vibration: whole-body vibration (WBV) and hand-arm vibration (HAV). The damage vibration does to the body depends on:

• the length of exposure
• the frequency, meaning the rate at which the surface or tool vibrates, measured in vibrations per second, or hertz (Hz)
• the amplitude, meaning the size of the vibration, which can be measured as acceleration, speed or distance covered

Hand-arm vibration. Long-term exposure from hand-held tools such as pneumatic tools (for example concrete breakers), chainsaws and grinders causes a range of conditions and diseases, including:

• white finger, also called "dead finger": damage to the hands that makes the fingers white and painful
• carpal tunnel syndrome
• sensory nerve damage
• muscle and joint damage in the hands and arms, such as tennis elbow

These conditions can have very serious consequences and can be permanently disabling after only a few years of uncontrolled exposure.

Whole-body vibration. Vibration and shocks transmitted through vehicle seats or platforms can contribute to back pain, particularly with poor posture and other physical demands. Back pain has many possible causes, and exposure does not by itself establish a diagnosis. Motion and shocks can also affect comfort and the ability to control a vehicle. HSE guidance focuses on back-pain risk; the broad organ-damage claims sometimes attributed to WBV should not be treated as established outcomes of ordinary occupational exposure.

The longer a worker is exposed to WBV, the greater the risk of health effects and muscular disorders.

When exposure should be assessed

National vibration requirements differ, while recognised measurement standards support assessment, including ISO 5349 for hand-arm vibration and ISO 2631 for whole-body vibration. Use a competent method appropriate to the equipment, real exposure and applicable law. To start a risk assessment:

• find out from employees and supervisors which processes, if any, involve regular exposure to vibration
• see whether equipment handbooks give any warnings of vibration risks
• ask employees whether they have any WBV or HAV symptoms, and whether the equipment produces high vibration or uncomfortable strain on the hands and arms

The exposure action value (EAV) is a daily amount of vibration exposure above which employers must act to control exposure. The higher the exposure, the greater the risk and the more action the employer needs to take. In Great Britain, the hand-arm vibration EAV is 2.5 m/s² A(8).

There is also a level that must not be exceeded. The exposure limit value (ELV) is the maximum 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.

Summary notes for Element 5 · Cheat sheet · Glossary. A study aid, not published or endorsed by NEBOSH.