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Vibration

Hand and arm vibration

Tingling or numb fingers are the first sign of harm caused by vibration. After a longer period, there is a risk of suffering from “white fingers”, which manifests itself by making your fingers white, cold and numb in cold weather. Only one or two fingers are affected initially, but if you continue to be exposed to vibration, more of your fingers will turn “white” – and possibly on both hands.

Stop work if you have an attack of “white fingers”. There is a greater risk of industrial accidents if your fingers are numb. At the same time, it may be difficult to do work involving fine movements.
Other subsequent effects may include permanent loss of sensation and grip, constant tingling in the fingers, pain in the shoulders and joints and an increased risk of arthritis.

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The risk of vibration injury is dependent upon how much vibration you are exposed to over an eight-hour working day. As a rule of thumb, injury can be avoided if your daily exposure to vibration does not exceed 2.5 m/s².

A vibration load of 2.5 m/s² is equivalent to you being exposed to a constant vibration level of:

  • 2.5 m/s² over 8 hours
  • 3.5 m/s² over 4 hours
  • 5 m/s² over 2 hours
  • 7 m/s² over 1 hour
  • 10 m/s² over 0.5 hour

The daily vibration load must not exceed 5 m/s². This limit is absolute and must not be exceeded. The action value indicates when the employer must act to reduce load. The action value is set to 2.5 m/s². Work may continue with a vibration load of between 2.5 and 5 m/s². However, the reason for the high load must be investigated, and attempts must be made to reduce it as much as possible. This can be achieved by means of planning and by using technical arrangements.
Work must be planned and executed so that nobody is exposed to harmful vibration. Technical arrangements must be used, or the exposure time must be limited.

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The following arrangements may reduce the load:

  • Use methods generating less vibration, e.g. blasting, diamond cutting and water jet cutting.
  • Plan the work to generate as little vibration as possible.
  • Where possible, replace handheld tools, e.g. by using remotely controlled tools/machinery.
  • Apply a set maintenance procedure for tools.
  • Bear in mind the vibration level when purchasing new machinery or tools.

The supplier must provide information on hand/arm vibration in usage instructions, sales documentation, etc. when 2.5 m/s² is exceeded.
Trial several different machines, or where appropriate use a working environment advisor when you want to assess a supplier’s information on the vibration of a machine when you buy new machinery.

Vibration-damping gloves can be used to supplement other vibration-damping measures, although they only have a very limited effect. Gloves only damp high-frequency vibration. Therefore, they will only damp the “whiplash” of the blow from e.g. a drilling hammer, but the risk of white fingers will remain the same. The same is true for most heavy tools in the field of building and construction.

Full-body vibration

Full-body vibration is vibration transmitted to the entire body, risking the health and safety of employees by causing pain in the lumbar region and injury to the spine

Full-body vibration is transmitted to the drivers of mobile machinery through the seat and floor.

The greater the intensity of the vibration and the longer it goes on for, the greater the risk of your body being affected. Rest periods may reduce the effect.

The daily vibration load describes how much vibration a person is exposed to over an eight-hour working day. The daily load is a combination of vibration intensity and the amount of time for which you are exposed to it.

Vibration acceleration is measured in m/s2 in three directions perpendicular to one another.

Avoid unnecessary vibration loads and ensure that the load is as small as possible. There is a full-body vibration limit of 1.15 m/s² which must not be exceeded, as well as an action value A(8) of 0.5 m/s².
The risk of injury increases in fixed working positions and with frequent twisting of your back. The same is true when your muscles are tired, or when your back is compressed following hard physical work. Jolts and unexpected movements caused by factors such as uneven surfaces or minor collisions also increase the risk of injury.

Purchasing machinery

It is important to ensure that the ergonomics in the driver’s cab are in order, that what the operator must see is clearly visible, and that all controls and actuators are positioned in such a way as to allow the operator to do his job without having to twist and turn in his seat.

It is also important to understand that an inefficient machine with not enough capacity for the job will result in longer exposure times. (In general, heavier machinery also vibrates less.)

  • Choose machinery with a low vibration level, but only compare figures from different suppliers if the same measurement method has been used.
  • If possible, buy vehicles with suspension.
  • Where necessary, involve a working environment advisor in your assessment.

Suppliers of machinery are obliged to:

  • Supply machinery with low vibration intensity.
  • Supply vehicles with seats which limit vibration transmitted to the driver as much as is reasonably possible.
  • Provide information on the vibration intensity. If it exceeds 0.5 m/s², the intensity must be stated.

Vibration intensity must be specified in the usage instructions, sales documentation and the technical documentation in general.

Reducing the risk of injury

  • Drive at a speed which is not too high for the surface on which you are driving.
  • Choose and mark out routes which do not have drain covers, holes, cobblestones, driving panels, etc.
  • If possible, even out the sections which are used often.
  • Avoid using solid wheels where possible.
  • Use a seat which is suitable for the vehicle, also taking into account the vibration frequency of the machine. The seat must offer good back support in relation to the movements involved in the work. It must be maintained, easy to adjust and adjusted to suit the driver. The driver must have received thorough instruction on how to adjust the seat.
  • The seat should have settings for forward/backward movement, backrest tilt, the weight of the driver and any variable lumbar support. In particular, good lumbar support and the setting relating to the weight of the driver are particularly important with regard to vibration.
  • Set the steering or controls to suit the driver, where possible.
  • The tyres on the vehicle must be correct and at the right pressure. Make sure that the vehicle’s suspension, shock absorbers, etc. are well maintained.