What is vibration?

Vibration is back-and-forth movements and shocks in solid objects, such as motor-driven machines. The magnitude of vibration is expressed as acceleration in the unit m/s² (metres per second squared). Vibration can be continuous or contain shocks.

Vibration is usually divided into two main types:

• Whole-body vibration affects the entire body. It is transmitted when a person stands or sits on a vibrating surface, such as on or in a vehicle or mobile machine.
• Hand-arm vibration occurs when a person works with hand-held machines or tools.

An employee may be exposed to both whole-body vibration and hand-arm vibration at the same time.

Which occupational groups are exposed to vibration?

There are many occupational groups that use vibrating work equipment. Some examples:

• carpenters – jigsaw, circular saw, reciprocating saw, drill, screwdriver
• fitters, welders and mechanics – grinding machine, nut runner, angle grinder, polishing machine
• repairers, bricklayers, plumbers, electricians – chipping machine, hammer drill, screwdriver, reciprocating saw
• sheet metal workers – rivet gun, nibbler
• park and property maintenance workers – brush cutter, lawn mower, chainsaw, grinder
• concrete and construction workers – chipping machine, ground vibrator/compacting machine
• dentists – dental drills with precision grips
• dental technicians – grinding dentures with filing machines
• machine and vehicle drivers – excavators, loaders, forklifts, buses.

When is vibration harmful?

When vibration reaches the body, it is amplified and dampened in different parts of the body. The intensity and frequency of the vibration (how fast the machine moves back and forth) together with the duration of exposure to vibration, determine the exposure value. The exposure values indicate the daily vibration exposure during an 8-hour working day and are designated A(8).

High exposure to vibration over a prolonged period can pose risks to health and increase the likelihood of workplace accidents. It is difficult to specify an exact limit at which vibration from work equipment becomes harmful to people. If the vibration exceeds any of the exposure values specified in our provisions on vibration, they are harmful. However, they can be harmful even below exposure limits, especially if the vibration includes shocks or impacts.

Therefore, there are two exposure values for daily vibration exposure, A(8):

• exposure action value A(8)
• exposure limit value A(8).

The employer must take different measures depending on whether the vibration exposure exceeds the action value or the limit value.

As an employer, you must carefully estimate the vibration exposure from each part of your operation and then analyse the highest values. This will enable you to identify which work equipment and work processes need to be addressed in order to reduce vibration.

Repeated shocks pose a particular risk

In jobs where employees are exposed to repeated shocks, the risks of injury and ill health are often underestimated. When you, as an employer, are conducting a risk assessment for these employees, it is therefore important to be extra observant and cautious.

Examples of occupations involving repetitive shocks:

• Car mechanics, when using various impact or percussive hand-held machines and tools.
• Building and civil engineering workers when using chipping machines and reciprocating saws.
• Sheet metal workers
• Vehicle and machine operators who drive vehicles and mobile machines on uneven surfaces or off-road. Even when the engine is idling, vibration is transmitted through the seat or feet to the entire body.

If the action value is exceeded – reduce exposure and make an action plan

If the vibration exposure for one or more employees exceeds the exposure action value, you as an employer are obliged to take action. The action value differs for different types of vibration:

• whole-body vibration: A(8) = 0.5 m/s²
• hand-arm vibration: A(8) = 2.5 m/s².

The measures must reduce vibration ¬exposure in order to get below the action value.

The employer is also responsible for ensuring that measures that are not implemented immediately are included in a written action plan. The action plan must specify the measures to be implemented, when they are to be implemented and who is responsible for their implementation.

In the case of hand-arm vibration, the employer must also arrange for medical checks for each individual employee whose exposure exceeds the exposure action value.

In the following cases, medical checks must be arranged even if the exposure action value is not exceeded:

• if the vibration exposure occurs in such a way that there may be reason to suspect that harmful health effects may arise, for example if the exposure involves a lot of shocks and impacts
• if the exposure has caused or given rise to suspicion of vibration injuries in another employee who has been exposed in a similar manner.

If the exposure limit value is exceeded – stop exposure immediately

The vibration exposure limit value must never be exceeded. The exposure limit value differs for the different types of vibration:

• whole-body vibration: A(8) = 1.1 m/s²
• hand-arm vibration: A(8) = 5.0 m/s².

If the values are still exceeded, the employer is obliged to

• take immediate measures to reduce vibration exposure to below the exceeded limit value
• investigate the reasons why the limit value has been exceeded
• take measures to ensure that the limit values are not exceeded in future.