Hand Arm Vibration (HAVs)

HAV was first listed as a prescribed disease in the United Kingdom in 1985 and in 1997 the High Court awarded £127,000 in compensation to seven coal miners for vibration white finger – a physical manifestation of HAVS.

Any equipment that vibrates and is held by hand poses a level of risk to the operator dependant on the magnitude of vibration and the duration of exposure. Amplitudes can vary significantly with tool design (the HSE gives the example of a hammer drill which can vary from 6 m/s² to 25 m/s²) but certain assumptions can be made to determine how long a worker can be exposed to particular vibration levels. Two limits apply to HAV exposure:

1. ELV – The limit above which workers cannot be exposed.
2. EAV – The limit above which the company is required to take certain actions.

Quantifying the level of risk can be very complex but the HSE provide guidance that simplifies the process. The first stage is to determine the vibration magnitude of the equipment. The following table shows typical values for equipment commonly used:

These values should be cross referenced with exposure times using either the ready reckoner or HAV calculator on the HSE website:

http://www.hse.gov.uk/vibration/hav/readyreckoner.htm

http://www.hse.gov.uk/vibration/hav/vibrationcalc.htm

Where the ELV is likely to be exceeded, work shall not go ahead. Alternative work methods must be considered.

Where the EAV is likely to be exceeded, actions should be taken to reduce the exposure to a level as low as reasonably practicable through actions in the following hierarchy:

1. Implement other working methods to eliminate or reduce exposure
2. Choose alternative equipment with lower vibration characteristics
3. Maintain equipment appropriately
4. Train employees to use equipment in a manner to reduce risk
5. Limit duration of work
6. Adjust work periods
7. Provide clothing to keep employees warm and dry

Staff who are likely to exceed the EAV or ELV should also be subject to regular health surveillance to detect any signs of Hand Arm Vibrations Syndrome (HAVS).

The following points should be considered when assessing the risk from HAV: 

1. Anti vibration gloves provide little or no protection from HAV and in some cases make exposure worse. They should be avoided with preference given to the provision of warm gloves during cold weather to promote circulation to the hands.
2. Vibration magnitudes quoted by manufacturers should be considered ‘best case scenario’ and is unlikely to reflect real world use. Unless alternate data such as direct measurement can be found, the HSE suggest doubling the magnitude quoted to achieve a realistic rating. The previous guidance table given by the HSE reflects this concern.
3. Exposure throughout the day should be summed together where different pieces of equipment are used. The HSE calculator should be used in these cases.
4. Tarmac is lower than concrete in terms of vibration magnitude.
5. Different tool bits give different characteristics and magnitude increases as they become worn. As an example a moil point is lower magnitude than a chisel point.
6. Smoking increase the risk of HAVS as it constricts the flow of blood to the hands
7. Certain medical condition such as diabetes increase the risk of HAVS as they reduce the flow of blood to the hands