Vibration

Trykkluftbor_COLOURBOX8156171.jpg Worker using an electric jackhammer. This work causes vibration exposure to his hands and arms. © Colourbox

Health effects of vibrations

Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium. The oscillations or movements may occur in different directions and frequencies, measured by the unit m/s2. In working life, we consider two types of vibration related to health of workers.

a) Hand-arm vibration.

Vibration exposure to the hand and arm is documented as causing specific negative health effects if the exposure is high and takes place for longer periods. The health effects are presented as hand-arm vibration syndrome (HAVS). It can cause three different types of clinical symptoms.

Hand-arm vibration syndrome

a) Disturbed circulation
b) Neurological symptoms
c) Musculoskeletal symptoms

A person with this disease might manifest one type of these symptoms, or all three types. A worker with disturbed circulation experiences “white fingers”; attacks with white, painful fingers. The symptoms are similar as those found among persons with Raynaud’s syndrome. The difference between persons with the Raynaud’s syndrome and the worker with HAVS, is the cause of the problem. Persons with Raynaud’s syndrome often inherit this type of disease; genetic aspects are of importance in the development of the disease. Persons with HAVS, develop this disease because they have been exposed to vibrations in their hands and arms. People who develop HAVS, and continue to work with vibrating tools, may develop other symptoms as well. Neurological symptoms, including numbness, tingling and loss of sensation in the fingers and hands may occur. Also, these patients may develop musculoskeletal symptoms and signs. They can develop pain in hands, elbows and shoulders. They may develop arthrosis of the joints, in particular the shoulder. The mechanism for developing problems from hand-arm vibration is probably related to changes in the small vessels of the affected limb, in addition to effects on the peripheral nerves.

The prevalence of HAVS among European workers who use hand held vibrating tools is relatively high. Mechanics, road construction workers and dentists are among the working groups with high prevalence of this disease. Few studies of this problem exist from developing countries. This is clearly an area for future research.

You can learn more about HAVS by watching this Hand Arm Vibration Safety Video.

b) Whole-body vibration

Vibrations can be experienced by the entire body, such as when you are onboard ships, and this type of exposure is named whole-body vibration. Exposure to whole-body vibration occurs also in vehicles on land and when standing on large machines. Whole-body vibration may cause back pain and different musculoskeletal problems. However it is not clear how this exposure harms the body. One theory is that the vibration causes micro-fractures in the spine.

Traktor_COLOURBOX6314218.jpg A worker experience whole-body vibration when sitting on a tractor. © Colourbox

Regulations

Exposure limits for vibration are established in several countries. However, vibrations are relatively difficult to measure, and require specific instruments and competence in measurement skills. This must be developed in different countries. Exposure limits should be established according to current international knowledge and data. International consensus standards describe useful methods for quantifying vibration severity for whole-body vibration in ISO 2631-1:1997 and for hand-transmitted vibration in ISO 5349:1986. In addition to these standards, other information can apply including information on the assessment of vibration exposure and protective and preventive measures provided for in the Working Environment (Air Pollution, Noise and Vibration) Convention (No. 148), and Recommendation (No. 156), 1977, as well as the ILO code of practice Protection of workers against noise and vibration in the working environment (Geneva, 1984).

Prevention

Employers should be aware of potential health effects from vibrating tools and try to re-design processes to avoid the need of using them. When purchasing equipment and industrial vehicles, employers should ascertain that the vibration exposure to the user is within prescribed national standards and that they do not otherwise pose a significant hazard or risk to the worker’s safety and health.

Manufacturers of vibrating tools should

(a) Provide vibration values for their tools, so the ones with lowest values can be chosen

(b) Provide information to ensure that vibration is controlled by correct installation of equipment

(c) Avoid resonance frequencies of the component parts of machinery and equipment

(d) Use anti-vibration handles; consistent with national laws and
regulations.

Regarding whole-body vibration, seating in vehicles should be designed to minimize transmission of vibration to the rider, and should permit an ergonomically good working position.

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This article is from the free online course:

Occupational Health in Developing Countries

University of Bergen