The term ‘vibrating tools’ refers to all kinds of handheld tools powered by an energy source, such as electricity, air, gas/petrol, ultrasound and water. The list of vibrating tools can be almost infinite.
According to the regulations, all employers must undertake a risk assessment, including assessment of the A(8) vibration exposure. The regulation lists two different possibilities:
Measure the A(8) exposures in the workplace according to standard ISO 5349.
A theoretical estimation based on the declared emission level (acceleration level) for each Tool.
Our recommendation is to implement method 2 for the risk assessment, and only use method 1 for suspected "worst case tools".
It should be noted that high-speed tools or instruments, such as dental drills and ultrasonic instruments, will cause A(8) exposure that is well below the action value (2.5 m/s2) for hand-arm vibration, even though these are potentially very harmful and can cause vibration damages.
1. Measure the A(8) exposure according to ISO 5349
The ISO 5349 standard specifies how to measure and assess the A(8) exposure through real-time tool measurements via a sensor attached to the tool. The emission level is then measured with a measuring device while the tool is powered on and in use
In practice, this method has proved to be both "difficult" and imprecise due to a variety of external factors affecting the measurement results. This includes how you grip the tool, hand size, tool wear, etc.
It is also difficult to replicate the results even if measured with the same person and set up. Furthermore, in many workplaces, it is common to use a large number of tools in one day. Measuring all of these is both time and cost intensive.
2. Theoretical estimation based on declared levels.
Within the EU, all tool manufacturers must declare the vibration levels on their tools according to a given standard (EN 60745, ISO 28 927 or equivalent).
Thus, for this option of Risk Assessment, you can either look in the tool's data sheet, or look in a national database, such as the one maintained by Umeå University.
However, note that new rules for this declaration are valid from December 2009. The new rules require that a tool shall be declared with respect to three acceleration directions instead of one (as specified in the older standard).
The revision of the measurement standard has led to the same tool (in many cases) receiving higher declared vibration levels compared to the older standard. In extreme cases, up to three times as high a level. On the other hand, some tools have got lower values due to changes in the revised test set up.
For employers with risk assessments based on the older vibration data, it may be advisable to conduct a new risk assessment based on latest declared vibration levels.
For those interested, you can read more about vibrations here http://www9.umu.se/phmed/envmed/forskning/vibration/ (page in Swedish)