Guidance on measurement and monitoring
Monitoring employees' exposure to vibration
Monitoring hand-arm vibration exposure all the time is probably not a good use of resources and monitoring alone is not enough to control risk. You still have to show that you have reduced vibration risk to as low as is reasonably practicable.
If you are using a monitoring system to prevent employees from reaching a set limit, be aware that retrospective recording can result in employees exceeding the set limit before you know they have done so.
If you choose to use a monitoring system, be sure you are using it correctly. Logbooks, data loggers and tool timers can be used to monitor and estimate hand-arm vibration exposure. However, HSE has found that different electronic monitoring systems can vary by up to 20% when monitoring the same task.
Do not confuse electronic monitoring systems with vibration measurement systems. Some electronic monitoring systems can calculate hand-arm vibration exposures. Be sure the vibration magnitude data you input into the device represents the tool in use, including a suitable margin to account for variability.
If you use calculated hand-arm vibration exposure data from an electronic monitoring system in your risk assessment, results must be in m/s2 A(8) or ‘exposure points’ so you can make valid comparisons with the Exposure Action and Limit Values.
Monitoring can help you make an initial assessment of exposure, or limit exposure to those employees identified as high risk by your occupational health provider.
You might carry out a period of monitoring exposure times to ensure that work has not changed or make periodic random sampling of exposures to verify that control measures are effective. You should not need to monitor daily vibration exposures.
Workplace vibration measurements
You only need to measure vibration magnitudes if you cannot get suitable data for your risk assessment from alternative sources.
If you want to obtain vibration measurements for your own tools you will need to arrange for a competent person to carry out measurements for you using specialised equipment.
Measurement results can be highly variable, depending on many factors, including the operator's technique, the condition of the work equipment, the material being processed and the measurement method.
The competence and experience of the person who makes the measurements is important so that they can recognise and take account of uncertainties in producing representative vibration data. The resources and advice below helps with this:
- appendix 2 of L140 and BS EN ISO 5349-2 should be used for guidance on measurement
- instrumentation should meet the specification for the measurement of hand-transmitted vibration given in BS EN ISO 8041. Accelerometers (vibration transducers) and the accessories and methods for mounting them should be carefully selected
- transducers should be mounted rigidly to the vibrating surface, as close as possible to where the vibration enters the hand. If fixed mounting systems are not feasible Appendix D of BS EN ISO 5349-2 gives advice on use of hand-held adaptors
- measurement results are unlikely to be representative if you measure away from the palm of the hand or use a measurement position that is on the fingers, back of the hand or wrist