GUIDE TO MEASURING AND ASSESSING
WORKPLACE EXPOSURE
TO WHOLE-BODY VIBRATION
This Guide provides information for people involved in the measurement and assessment of workplace
vibration exposures from vibrating plant. Plant includes machinery, equipment, appliances, containers,
implements and tools and components or anything fitted or connected to those things. Plant also includes
items as diverse as lifts, cranes, computers, conveyors, forklifts, vehicles, power tools and amusement
devices.
This Guide should be read and used together with the Guide to managing risks of whole-body vibration in
workplaces.
The Guide forms part of a series of guides that includes information on hand-arm vibration.
What is whole-body vibration?
Whole-body vibration (WBV) is vibration transmitted to the whole body by the surface supporting it, that is,
via a seat or floor. It is commonly experienced by drivers, operators and passengers in mobile plant when
travelling over uneven surfaces and can also be experienced by workers in control rooms of stationary plant.
WBV includes sharp impact-like shocks and jolts.
Key terms used in this Guide
Exposure action value means the level of daily vibration exposure to whole-body vibration (WBV) for any
worker above which steps should be taken to reduce exposure to WBV.
Exposure limit value means the level of daily vibration exposure to WBV for any worker which should not
be exceeded.
Daily vibration exposure A(8) means the quantity of WBV to which a worker is exposed during a working
day, normalised to an 8 hour reference period, which takes account of the magnitude and duration of the
vibration. Daily vibration exposure is derived from the magnitude of the vibration (vibration total value) and
the daily exposure duration.
Vibration dose value is a preferred measurement for exposure to jolts, shocks and intermittent vibration
because it is sensitive to peaks in acceleration levels.
Measuring vibration levels
Measurement of WBV can be difficult and complex. When workers perceive WBV is unpleasant it is likely
their exposure to vibration is reaching levels which could pose a risk to health. This may be used as an
indicator of a WBV problem and controls should be put in place to reduce exposure.
Measurement of WBV by a competent person may be needed when:

no adequate information is available from other sources

the plant is being used differently from the way it was when previously tested, or

there are concerns about whether controls have been effective.
You may choose to make the vibration measurements in-house or to employ a specialist consultant. In either
case, it is important that whoever does the vibration measurements is competent.
Exposure to WBV should be evaluated using the method defined in AS 2670.1. Evaluation of human
exposure to whole-body vibration - General requirements. Detailed practical guidance on using the method
for measurement of vibration at the workplace is given in EN 14253:2003. Mechanical Vibration –
Measurement And Calculation Of Occupational Exposure To Whole-body Vibration With Reference To
Health - Practical Guidance. The detail of how to make measurements of WBV is beyond the scope of this
document.
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There is currently no workplace exposure standard established in Australia for WBV. In order to work out
how much WBV exposure is likely to pose a risk using daily vibration exposure A(8) or vibration dose value it
is useful to make a comparison to an accepted standard.
The European Union has established an exposure action value and exposure limit value for WBV.
Figure 1 EU Directive
Exposure action value and exposure limit value for WBV under the
EU 2002/44/EC Physical Agents (Vibration) Directive
Exposure Action Value
If daily vibration exposure is likely to exceed an A(8) of 0.5 m/s2 or a vibration dose value of 9.1
m/s1.75 action should be taken to reduce exposure to below this value.
Exposure Limit Value
Controls must be put in place to ensure that a worker is not exposed under any circumstances to
a daily vibration exposure A(8) of more than 1.15 m/s2 or vibration dose value of 21 m/s1.75.
EXPOSURE TO WHOLE-BODY VIBRATION
Daily vibration exposure A(8)
Exposure to individual sources of WBV is calculated from the magnitude of vibration expressed as
acceleration in metres per second squared (m/s2) and the length of time of exposure.
The daily vibration exposure A(8), also expressed in m/s2, is the amount of vibration to which a worker is
exposed during a working day, normalised to an 8 hour reference period.
Vibration Dose Value (VDV)
In situations where workers are exposed to intermittent WBV including shocks or jolts rather than constant
vibration an alternative to the daily vibration exposure called the vibration dose value (VDV) gives a more
representative value.
Unlike the vibration magnitude the measured VDV is a cumulative value. That is, VDV increases with
measurement time. It is therefore important to know the length of time of the measurement as well as the
total time a worker is exposed to that source of vibration per day.
Both daily vibration exposure A(8) and vibration dose value measures are dependent on measured actual
vibration values for the item of plant.
Adjustment for extended working days
Longer shifts are already taken into account in the calculation of A(8) so no further adjustment to the
calculation of the daily vibration exposure A(8) is needed for shifts longer than 8 hours.
Calculation of VDV includes time of measurement and time of exposure and as long as the VDV is
calculated taking exposure time into account, there is no need to adjust the value for different shift lengths
Uncertainty in assessment of exposure
Where vibration magnitude and exposure time are measured the uncertainties associated with the evaluation
of daily vibration exposure A(8) can mean the calculated value can be as much as 20 percent above the true
value to 40 percent below. Where either the exposure time or the vibration magnitude is estimated—for
example, based on information from the worker (exposure time) or manufacturer (magnitude)—then the
uncertainty in the evaluation of daily vibration exposure A(8) can be much higher.
Measurement axes
For WBV the axis with the highest average root mean square (RMS) acceleration is used in calculation of the
daily vibration exposure A(8). Figure 2 shows the standard orientation of the x, y, and z axes. The
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measurements taken on the x- and y- axes are given a weighting of 1.4 times the measured value to reflect
their contribution to health effects. This is different from hand-arm vibration assessment in which the vibration
measurement is the triaxial sum of the acceleration experienced by the worker in the three axes.
Figure 2 Vibration measurement axes in both seated and standing positions
Daily vibration exposure A(8)
Exposure to WBV should be evaluated using the methods defined in AS 2670.1 Evaluation of human
exposure to whole-body vibration - General requirements.
The daily vibration exposure A(8) for a worker carrying out one process or operating one item of plant can be
calculated from a magnitude and exposure time using the equation:
𝑇
𝐴(8) = 𝑎𝑤 √
𝑇0
where:

𝑎𝑤 is the vibration magnitude (in m/s²) on the axis which measured highest, including the weighting
factor for the x- and y-axes.

T is the actual duration of exposure to the vibration magnitude 𝑎𝑤 .

T0 is the reference duration of eight hours. Like vibration magnitude the daily vibration exposure A(8)
has units of metres per second squared (m/s²).
The value of 𝑎𝑤 , the vibration magnitude, may come from measured data, manufacturer’s information or
other sources like online databases.
If a person is exposed to more than one source of WBV then partial vibration exposures are calculated from
the magnitude and duration for each source.
The overall daily vibration exposure A(8) can be calculated from the partial vibration exposure values using
the equation:
𝐴(8) = √𝐴1 (8)2 + 𝐴2 (8)2 + …
where A1(8), A2(8), etcetera are the partial vibration exposure values for the different vibration sources.
It is important to work out the daily vibration exposure A(8) separately for each of the three axes, as it is the
total on the highest axis the worker is exposed to which should be compared to the exposure action value
and exposure limit value.
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An easy way of working out the daily vibration exposure A(8) and comparing it to the exposure action value
and exposure limit value is to use an exposure points system (see Table 2). This system can be used
regardless of the source of the vibration magnitude.
Vibration dose value
Vibration dose value is more sensitive to peaks in acceleration than the RMS acceleration and is calculated
as the root mean quad of the acceleration. This gives a result in m/s 1.75. As with the daily vibration exposure
A(8) vibration dose value uses the same weighing factors of 1.4 on the x- and y-axes.
It is unlikely published vibration dose values will be available and measurements will have to be taken to
determine what the vibration dose value is for a particular piece of plant in a workplace. If vibration dose
values are available the daily vibration dose value for single source and multiple sources can be worked out
as below:
Calculation of the Daily VDVexp for each axis can be done using the equation:
𝑉𝐷𝑉𝑒𝑥𝑝,𝑥 = 1.4 𝑉𝐷𝑉𝑥 (
𝑇𝑒𝑥𝑝 1/4
)
𝑇𝑚𝑒𝑎𝑠
where

VDVx is the measured or otherwise found VDV on the x-axis.

Texp is the daily duration of exposure to the source of WBV.

Tmeas is the time over which the VDVx was measured.
An equivalent equation is used on the y-axis, while the equation for z-axis does not have the 1.4 weighting
factor.
If a worker is exposed to more than one source of WBV and vibration dose values are available for use the
total vibration dose value for each axis is calculated using the equation:
4
4
4
𝑉𝐷𝑉𝑥 = (𝑉𝐷𝑉𝑥1
+ 𝑉𝐷𝑉𝑥2
+ 𝑉𝐷𝑉𝑥3
+. . . )1/4
where VDVx1, VDVx2 et cetera are the partial vibration dose values for each source on the x-axis. The
vibration dose value which is highest of the x-, y- and z-axis is the daily vibration dose value.
There is no simple exposure points system for assessing WBV exposures using vibration dose values so
they must be calculated using equations. The Health and Safety Executive (UK) has a downloadable tool to
help with these calculations www.hse.gov.uk/vibration/wbv/wbv.xls.
Manufacturer declared emission values and other data sources
Manufacturer’s data may give a useful indication of the vibration exposure of workers. Where WBV exposure
is dependent on the quality of road surfaces, plant speeds and other factors like how the plant is operated,
and any attachment fitted to the plant, it may be necessary to confirm your initial exposure assessment by
making measurements of vibration magnitudes. A key indicator that WBV is exceeding the exposure limit
value is workers reporting discomfort or temporary lower back pain.
There are other sources of information on WBV magnitudes which are often sufficient to allow you to decide
whether the exposure action value or the exposure limit value is likely to be exceeded. These include
specialist vibration consultants, trade associations and government bodies. Some data can also be found in
various technical or scientific publications and on the Internet. Figure 3 gives some idea of the average and
ranges of vibration magnitudes for some commonly used mobile plant.
Ideally you should use WBV information for the plant—make and model—you plan to use. However, if this is
not available you may need to use information relating to similar plant as a starting point and replacing the
data with more accurate values when this becomes available.
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Figure 3 Examples of vibration magnitude for some common mobile plant 1
When choosing published WBV information the factors you need to take account of in making your choice
include:

the type of plant (e.g. fork-lift truck)

the class of plant (e.g. power or size)
1
From the EU good practice guide on Whole Body Vibration
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
the power source (e.g. electric or combustion engine)

any anti-vibration features (e.g. suspension systems, suspended cab and seats)

the task the plant was used for when producing the vibration information

the speed it was operated at, and

the type of surface it was run on.
When using published vibration data it is good practice to try to compare data from two or more sources.
Duration of Exposure
Before the daily vibration exposure A(8) can be estimated you need to know the total daily duration of
exposure to the vibration from the plant used. You should be careful to use data compatible with your
vibration magnitude data, for example if your vibration magnitude data is based on measurements when the
plant was working then count only the time the worker is exposed to vibration. Plant operators questioned on
their typical daily duration of vibration exposure usually include periods without vibration exposure, for
example standing or leaving the mobile plant altogether.
Usually the vibration occurs when the plant is travelling and will dominate vibration exposures. However,
some exposures are dominated by operations being performed while the plant is stationary like excavators
and tree harvesters.
Work patterns need careful consideration. For example, some workers may only operate plant for certain
periods in a day. Typical usage patterns should be established as these will be an important factor in
calculating a worker’s likely vibration exposure.
Daily vibration exposure using the exposure points system
A simple method for determining daily WBV exposure is the use of a points based system. The exposure
scores corresponding to the exposure action value and exposure limit value are:

exposure action value (0.5 m/s²) = 100 points, and

exposure limit value (1.15 m/s²) = 529 points.
With knowledge of the whole-body vibration acceleration 𝑎𝑤 , which axis it was determined on and the length
of exposure for each WBV activity a worker is exposed to in a day, it is easy to work out how many exposure
points have been accumulated using the exposure points in Table 1.
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Acceleration x k (m/s2)
Table 1 Exposure points2
2
50
100
200
400
600
800
1000
1200
1600
2000
2400
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
45
41
36
32
28
25
21
18
15
13
10
8
6
5
3
2
1
1
15m
90
81
72
64
56
49
42
36
30
25
20
16
12
9
6
4
2
1
30m
180
160
145
130
115
98
85
72
61
50
41
32
25
18
13
8
5
2
1h
360
325
290
255
225
195
170
145
120
100
81
64
49
36
25
16
9
4
2h
540
485
435
385
340
295
255
215
180
150
120
96
74
54
38
24
14
6
3h
720
650
580
510
450
390
340
290
240
200
160
130
98
72
50
32
18
8
4h
905
810
725
640
565
490
425
360
305
250
205
46
125
90
63
40
23
10
5h
1100
970
865
770
675
590
505
430
365
300
245
190
145
110
75
48
27
12
6h
1450
1300
1150
1000
900
785
675
575
485
400
325
255
195
145
100
64
36
16
8h
1800
1600
1450
1300
1150
980
845
720
605
500
405
320
245
180
125
80
45
20
10h
2150
1950
1750
1550
1350
1200
1000
885
725
600
485
385
295
215
150
96
54
24
12h
Daily Exposure Time
Example using the exposure points system
A worker spends:

an hour driving a grader to repair a dirt road, and

then 5 hours ploughing a paddock.
The measured vibration magnitudes were greatest on the z-axis—up and down—for both activities.
Table 2 Calculations using the exposure points system
Activity
Measured vibration
on highest axis m/s2
Exposure time
(hours)
Exposure Points
Grader
1.2 (z)
1
72
Tractor- ploughing
0.8 (z)
5
160
TOTAL
2
232
From the EU good practice guide on Whole Body Vibration.
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The farmer’s total exposure for the day is 232 points. This is between the exposure action value and the
exposure limit value. The farmer should take action to reduce the exposure. This could involve reducing the
amount of time spent ploughing, reducing speed over the rough areas at the end of the paddock or making
adjustments to the tractor’s suspension seat. It is most likely a combination of these will be needed to reduce
exposures to below the exposure action value.
Further information
The following documents and websites may be useful to improve understanding of WBV and help work out
how to control exposure to WBV:

Guide to managing risks of whole-body vibration in the workplace

Safe Work Australia reports on vibration:


o
Implementation and Effectiveness of the European Directive Relating to Vibration in the Workplace
o
National Hazard Exposure Worker Surveillance: Vibration exposure and the provision of vibration
control measures in Australian Workplaces
UK Health and Safety Executive:
o
HSE Information Sheet Whole-body Vibration in Agriculture AIS20 (revision)
o
Control back-pain risks from whole-body vibration - Advice for employers on the Control of Vibration
at Work Regulations 2005 INDG 242
o
Drive away bad backs - Advice for mobile machine operators and drivers IND404
o
Whole-body vibration. Control of Vibration at Work Regulations 2005
Web-based tools:
o

Sources of emissions data:
o

Web-based calculators are available that simplify the process of doing daily vibration exposure
calculations e.g. http://www.hse.gov.uk/vibration/wbv/calculator.htm
http://www.vibration.db.umu.se/HkvSok.aspx?lang=en
Standards for measurement and assessment:
o
AS 2670.1-2001: Evaluation of human exposure to whole-body vibration - General requirements,
and
o
AS 2670.1-2001/Amdt 1-2013 Evaluation of human exposure to whole-body vibration - General
requirements
For further information see the Safe Work Australia website (www.swa.gov.au).
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