Friday, 25 March 2011 05:38


Written By: Griffin, Michael J.
Rate this item
(1 Vote)

Vibration is oscillatory motion. This chapter summarizes human responses to whole-body vibration, hand-transmitted vibration and the causes of motion sickness.

Whole-body vibration occurs when the body is supported on a surface which is vibrating (e.g., when sitting on a seat which vibrates, standing on a vibrating floor or recumbent on a vibrating surface). Whole-body vibration occurs in all forms of transport and when working near some industrial machinery.

Hand-transmitted vibration is the vibration that enters the body through the hands. It is caused by various processes in industry, agriculture, mining and construction where vibrating tools or workpieces are grasped or pushed by the hands or fingers. Exposure to hand-transmitted vibration can lead to the development of several disorders.

Motion sickness can be caused by low frequency oscillation of the body, some types of rotation of the body and movement of displays relative to the body.


Oscillatory displacements of an object involve alternately a velocity in one direction and then a velocity in the opposite direction. This change of velocity means that the object is constantly accelerating, first in one direction and then in the opposite direction. The magnitude of a vibration can be quantified by its displacement, its velocity or its acceleration. For practical convenience, the acceleration is usually measured with accelerometers. The units of acceleration are metres per second per second (m/s2). The acceleration due to the Earth’s gravity is approximately 9.81 m/s2.

The magnitude of an oscillation can be expressed as the distance between the extremities reached by the motion (the peak-to-peak value) or the distance from some central point to the maximum deviation (the peak value). Often, the magnitude of vibration is expressed in terms of an average measure of the acceleration of the oscillatory motion, usually the root-mean-square value (m/s2 r.m.s.). For a single frequency (sinusoidal) motion, the r.m.s. value is the peak value divided by √2.

For a sinusoidal motion the acceleration, a (in m/s2), can be calculated from the frequency, f (in cycles per second), and the displacement, d (in metres):


This expression may be used to convert acceleration measurements to displacements, but it is only accurate when the motion occurs at a single frequency.

Logarithmic scales for quantifying vibration magnitudes in decibels are sometimes used. When using the reference level in International Standard 1683, the acceleration level, La, is expressed by La = 20 log10(a/a0), where a is the measured acceleration (in m/s2 r.m.s.) and a0 is the reference level of 10-6 m/s2. Other reference levels are used in some countries.



The frequency of vibration, which is expressed in cycles per second (hertz, Hz), affects the extent to which vibration is transmitted to the body (e.g., to the surface of a seat or the handle of a vibratory tool), the extent to which it is transmitted through the body (e.g., from the seat to the head), and the effect of vibration in the body. The relation between the displacement and the acceleration of a motion are also dependent on the frequency of oscillation: a displacement of one millimetre corresponds to a very low acceleration at low frequencies but a very high acceleration at high frequencies; the vibration displacement visible to the human eye does not provide a good indication of vibration acceleration.

The effects of whole-body vibration are usually greatest at the lower end of the range, from 0.5 to 100 Hz. For hand-transmitted vibration, frequencies as high as 1,000 Hz or more may have detrimental effects. Frequencies below about 0.5 Hz can cause motion sickness.

The frequency content of vibration can be shown in spectra. For many types of whole-body and hand-transmitted vibration the spectra are complex, with some motion occurring at all frequencies. Nevertheless, there are often peaks, which show the frequencies at which most of the vibration occurs.

Since human responses to vibration vary according to the vibration frequency, it is necessary to weight the measured vibration according to how much vibration occurs at each frequency. Frequency weightings reflect the extent to which vibration causes the undesired effect at each frequency. Weightings are required for each axis of vibration. Different frequency weightings are required for whole-body vibration, hand-transmitted vibration and motion sickness.


Vibration may take place in three translational directions and three rotational directions. For seated persons, the translational axes are designated x-axis (fore-and-aft), y-axis (lateral) and
z-axis (vertical). Rotations about the x-, y- and z-axes are designated rx (roll), ry (pitch) and rz (yaw), respectively. Vibration is usually measured at the interfaces between the body and the vibration. The principal coordinate systems for measuring vibration with respect to whole-body and hand-transmitted vibration are illustrated in the next two articles in the chapter.


Human responses to vibration depend on the total duration of vibration exposure. If the characteristics of vibration do not change with time, the root-mean-square vibration provides a convenient measure of the average vibration magnitude. A stopwatch may then be sufficient to assess the exposure duration. The severity of the average magnitude and total duration can be assessed by reference to the standards in the following articles.

If the vibration characteristics vary, the measured average vibration will depend on the period over which it is measured. Furthermore, root-mean-square acceleration is believed to underestimate the severity of motions which contain shocks, or are otherwise highly intermittent.

Many occupational exposures are intermittent, vary in magnitude from moment to moment or contain occasional shocks. The severity of such complex motions can be accumulated in a manner which gives appropriate weight to, for example, short periods of high magnitude vibration and long periods of low magnitude vibration. Different methods of calculating doses are used (see “Whole-body vibration”; “Hand-transmitted vibration”; and “Motion sickness” in this chapter).



Read 4928 times Last modified on Tuesday, 26 July 2022 21:41
More in this category: Whole-Body Vibration »

" DISCLAIMER: The ILO does not take responsibility for content presented on this web portal that is presented in any language other than English, which is the language used for the initial production and peer-review of original content. Certain statistics have not been updated since the production of the 4th edition of the Encyclopaedia (1998)."


Part I. The Body
Cardiovascular System
Physical, Chemical, and Biological Hazards
Digestive System
Mental Health
Mood and Affect
Musculoskeletal System
Nervous System
Renal-Urinary System
Reproductive System
Respiratory System
Sensory Systems
Skin Diseases
Systematic Conditions
Part II. Health Care
First Aid & Emergency Medical Services
Health Protection & Promotion
Occupational Health Services
Part III. Management & Policy
Disability and Work
Education and Training
Case Studies
Ethical Issues
Development, Technology, and Trade
Labour Relations and Human Resource Management
Resources: Information and OSH
Resources, Institutional, Structural and Legal
Community level
Regional and National Examples
International, Government and Non-Governmental Safety and Health
Work and Workers
Worker's Compensation Systems
Topics In Workers Compensation Systems
Part IV. Tools and Approaches
Biological Monitoring
Epidemiology and Statistics
Goals, Principles and Methods
Physical and Physiological Aspects
Organizational Aspects of Work
Work Systems Design
Designing for Everyone
Diversity and Importance of Ergonomics
Occupational Hygiene
Personal Protection
Record Systems and Surveillance
General Principles of Toxicology
Mechanisms of Toxicity
Toxicology Test Methods
Regulatory Toxicology
Part V. Psychosocial and Organizational Factors
Psychosocial and Organizational Factors
Theories of Job Stress
Chronic Health Effects
Stress Reactions
Individual Factors
Career Development
Macro-Organizational Factors
Job Security
Interpersonal Factors
Factors Intrinsic to the Job
Organizations and Health and Safety
Part VI. General Hazards
Barometric Pressure Increased
Barometric Pressure Reduced
Biological Hazards
Disasters, Natural and Technological
Heat and Cold
Hours of Work
Indoor Air Quality
Indoor Environmental Control
Radiation: Ionizing
Radiation: Non-Ionizing
Visual Display Units
Part VII. The Environment
Environmental Health Hazards
Environmental Policy
Environmental Pollution Control
Part VIII. Accidents and Safety Management
Accident Prevention
Audits, Inspections and Investigations
Safety Applications
Safety Policy and Leadership
Safety Programs
Part IX. Chemicals
Using, Storing and Transporting Chemicals
Minerals and Agricultural Chemicals
Metals: Chemical Properties and Toxicity
Part X. Industries Based on Biological Resources
Agriculture and Natural Resources Based Industries
Farming Systems
Food and Fibre Crops
Tree, Bramble and Vine Crops
Specialty Crops
Beverage Crops
Health and Environmental Issues
Beverage Industry
Food Industry
Overview and Health Effects
Food Processing Sectors
Livestock Rearing
Paper and Pulp Industry
Major Sectors and Processes
Disease and Injury Patterns
Part XI. Industries Based on Natural Resources
Iron and Steel
Mining and Quarrying
Oil Exploration and Distribution
Power Generation and Distribution
Part XII. Chemical Industries
Chemical Processing
Examples of Chemical Processing Operations
Oil and Natural Gas
Pharmaceutical Industry
Rubber Industry
Part XIII. Manufacturing Industries
Electrical Appliances and Equipment
Metal Processing and Metal Working Industry
Smelting and Refining Operations
Metal Processing and Metal Working
Microelectronics and Semiconductors
Glass, Pottery and Related Materials
Printing, Photography and Reproduction Industry
Part XIV. Textile and Apparel Industries
Clothing and Finished Textile Products
Leather, Fur and Footwear
Textile Goods Industry
Part XV. Transport Industries
Aerospace Manufacture and Maintenance
Motor Vehicles and Heavy Equipment
Ship and Boat Building and Repair
Part XVI. Construction
Health, Prevention and Management
Major Sectors and Their Hazards
Tools, Equipment and Materials
Part XVII. Services and Trade
Education and Training Services
Emergency and Security Services
Emergency and Security Services Resources
Entertainment and the Arts
Arts and Crafts
Performing and Media Arts
Entertainment and the Arts Resources
Health Care Facilities and Services
Ergonomics and Health Care
The Physical Environment and Health Care
Healthcare Workers and Infectious Diseases
Chemicals in the Health Care Environment
The Hospital Environment
Health Care Facilities and Services Resources
Hotels and Restaurants
Office and Retail Trades
Personal and Community Services
Public and Government Services
Transport Industry and Warehousing
Air Transport
Road Transport
Rail Transport
Water Transport
Part XVIII. Guides
Guide to Occupations
Guide to Chemicals
Guide to Units and Abbreviations

Vibration References

Alexander, SJ, M Cotzin, JB Klee, and GR Wendt. 1947. Studies of motion sickness XVI: The effects upon sickness rates of waves and various frequencies but identical acceleration. J Exp Psy 37:440-447.

American Conference of Governmental Industrial Hygienists (ACGIH). 1992. Hand-arm (segmental) vibration. In Threshold Limit Values and Biological Exposures Indices for 1992-1993. Cincinnati, Ohio: ACGIH.

Bongers, PM and HC Boshuizen. 1990. Back Disorders and Whole-Body Vibration at Work. Thesis. Amsterdam: University of Amsterdam.

British Standards Institution (BSI). 1987a. Measurement and Evaluation of Human Exposure to Vibration Transmitted to the Hand. BS 6842. London: BSI.

—. 1987b. Measurement and Evaluation of Human Exposure to Whole-Body Mechanical Vibration and Repeated Shock. BS 6841. London: BSI.

Council of the European Communities (CEC). 1989. Council Directive of 14 June 1989 on the approximation of the laws of the Member States relating to machinery. Off J Eur Communities L 183:9-32.

Council of the European Union. 1994. Amended proposal for a Council Directive on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents. Off J Eur Communities C230 (19 August):3-29.

Dupuis, H and G Zerlett. 1986. The Effects of Whole-Body Vibration. Berlin: Springer-Verlag.

Griffin, MJ. 1990. Handbook of Human Vibration. London: Academic Press.

Hamilton, A. 1918. A Study of Spastic Anemia in the Hands of Stonecutters. Industrial Accidents and Hygiene Series no. 19. Bulletin No. 236. Washington, DC: Department of Labor Statistics.

Hasan, J. 1970. Biomedical aspects of low-frequency vibration. Work Environ Health 6(1):19-45.

International Organization for Standardization (ISO). 1974. Guide for the Evaluation of Human Exposure to Whole-Body Vibration. Geneva: ISO.

—. 1985. Evaluation of Human Exposure to Whole-Body Vibration. Part 1: General Requirements. ISO 2631/1. Geneva: ISO.

—. 1986. Mechanical Vibration-Guidelines for the Measurement and the Assessment of Human Exposure to Hand-Transmitted Vibration. ISO 5349. Geneva: ISO.

—. 1988. Hand-Held Portable Power Tools - Measurement of Vibrations at the Handle. Part 1: General. ISO 8662/1. Geneva: ISO.

ISSA International Section for Research. 1989. Vibration At Work. Paris: INRS.

Lawther, A and MJ Griffin. 1986. Prediction of the incidence of motion sickness from the magnitude, frequency and duration of vertical oscillation. J Acoust Soc Am 82:957-966.

McCauley, ME, JW Royal, CD Wilie, JF O’Hanlon, and RR Mackie. 1976. Motion Sickness Incidence: Exploratory Studies of Habituation Pitch and Roll, and the Refinement of a Mathematical Model. Technical Report No. 1732-2. Golets, Calif: Human Factors Research.

Rumjancev, GI. 1966. Gigiena truda v proizvodstve sbornogo shelezobetona [Occupational hygiene in the production of reinforced concrete]. Medicina (Moscow):1-128.

Schmidt, M. 1987. Die gemeinsame Einwirkung von Lärm und Ganzkörpervibration und deren Auswirkungen auf den Höverlust bei Agrotechnikern. Dissertation A. Halle, Germany: Landwirtschaftliche Fakultät der Martin-Luther-Universität.

Seidel, H. 1975. Systematische Darstellung physiologischer Reaktionen auf Ganzkörperschwingungen in vertikaler Richtung (Z-Achse) zur Ermittlung von biologischen Bewertungsparametern. Ergonom Berichte 15:18-39.

Seidel, H and R Heide. 1986. Long-term effects of whole-body vibration: A critical survey of the literature. Int Arch Occup Environ Health 58:1-26.

Seidel, H, R Blüthner, J Martin, G Menzel, R Panuska, and P Ullsperger. 1992. Effects of isolated and combined exposures to whole-body vibration and noise on auditory-event related brain potentials and psychophysical assessment. Eur J Appl Physiol Occup Phys 65:376-382.

Stockholm Workshop 86. 1987. Symptomatology and diagnostic methods in the hand-arm vibration syndrome. Scand J Work Environ Health 13:271-388.