This guide is for persons conducting a business or undertaking (PCBUs) that carry out work involving machines. It explains how to identify and manage the risks from excessive whole body vibration (WBV).
1.0 Who is this guide for?
WBV occurs when vibration (including bumps, shocks and jolts) passes through someone’s body from the surface they are sitting or standing on.
Workers can be exposed to WBV if they regularly drive, ride in, or operate machines that travel over rough surfaces or have a vibrating function. Examples include tractors and mobile machinery like earth movers and bulldozers.
Long term exposure to excessive WBV could harm workers.
As a PCBU1, you must ensure, so far as is reasonably practicable, the health and safety of workers, and that other persons are not put at risk by your work.
You must manage the health and safety risks to workers and others that arise from being exposed to the work carried out by your business.
2.0 What are the health risks of excessive WBV?
Long term exposure to excessive WBV could harm workers.
Lower back, neck or shoulder pain or other discomfort could be signs that workers are being exposed to excessive WBV. However, there can be other work and non-work factors that could contribute to these symptoms.
People who are exposed to noise and vibration at the same time are more likely to lose their hearing than people who are exposed to noise alone.
For information about vibration noise control, see our website: worksafe.govt.nz
3.0 How can you work out if exposure to WBV is something you need to deal with?
Workers are commonly exposed to WBV when they regularly drive, ride in,
or operate machines:
- off-road (for example, tractors and mobile machinery like earth movers, bulldozers)
- on unsealed or poorly maintained roads
- under conditions the machine is not designed for (for example, driving on-road vehicles off-road).
Workers can be exposed to WBV when using machinery like forklifts, or when riding on machines like trains or on maritime vessels.
Workers can also be exposed by standing on a platform attached to a machine that vibrates (for example, a concrete crushing plant).
Do you need to manage the risks from excessive WBV?
This will depend on how much the machines workers use vibrate, and how long and how often workers are exposed to the vibration.
There is a recommended maximum daily amount of WBV that workers should not exceed.
- We recommend that workers have a maximum daily exposure limit of 1.15m/s2 (8 hour average) or vibration dose value of 21m/s1.75.
- We expect you to put control measures in place if your workers are exposed to ‘the exposure action value’ of 0.5m/s2 (8 hour average) or more, or vibration dose value of 9.1m/s1.75 or more.
See Section 4 for information about monitoring the amount of vibration workers are being exposed to.
There are many factors that can influence the effects of exposure to WBV.
- the condition of the machine
- the vibration intensity
- the duration of exposure (time/day, frequency)
- the design of the cab and seat, or the standing surface
- the type of tyres or tyre pressure
- operator skill
- operator health and medical history.
To work out whether your workers are at risk, think about:
- the machine
- how the work is organised
- the task
- your workers.
You must engage with workers and their representatives when assessing risks to work health and safety (Appendix 4).
Section 4 describes how monitoring can help to identify or confirm health risks from WBV.
What is the vibration level for the machine?
See the manufacturer’s user manual.
Does the machine have suspension systems (for example, for the cab and seat, or standing surface) designed to minimise vibration, shocks and jolts?
Is the machine working optimally?
As a first step, you could seek help from the machine’s importer, supplier, designer or service person to check this.
Is the machine regularly maintained (including suspension systems and seat suspension)?
Machines that are older or that are not well-maintained usually vibrate more
Is the machine the right one for the task? Is it fit-for-purpose?
Using the wrong machine can mean work takes longer, increasing exposure to vibration. Using over-powered machines expose workers to higher levels of vibration.
What is the vibration level for the task?
See the manufacturer’s user manual for vibration data. The higher the vibration, the greater the risk.
How long does the task take?
Have you taken into account cumulative exposure from use of other machines in the same work shift?
The longer workers are exposed to vibration, the more chance of harm from WBV.
Is the machine being used as designed?
Is the machine to be used off-road, on unsealed or poorly maintained roads or under conditions the machine’s not designed for?
The rougher the surface, the more vibration.
Does the machine have suitable tyres for the terrain?
The wrong tyres or the wrong tyre pressure can expose workers to higher levels of vibration.
How hard is the material that machines (such as earth moving vehicles) will work with (for example, is it concrete, is it soft soil)?
The harder the material, the more vibration.
Does the task involve awkward postures or frequent twisting or reaching?
How the work is organised
How long are your workers exposed to the vibration?
- How many hours within the shift involve operating the machine(s)?
- How often do your workers take breaks?
- How long are they exposed to high levels of WBV versus lower levels?
- How often do they operate the machinery? Every day?
The longer workers are exposed to vibration, the more chance of harm from WBV
Do your workers always use the right machine for the job?
Using the wrong machine can mean work takes longer, increasing exposure to vibration.
Have they been trained to properly use the machine including adjusting the seat?
Are they being exposed to WBV above the recommended levels (see the blue box above for recommended levels)
Do they feel that WBV is uncomfortable?
If yes, they could be being exposed to too much WBV. See the next section for information about this.
Are they showing signs of potentially being exposed to excessive WBV (for example, lower back, neck or shoulder pain)?
How is their general health?
Pre-existing injuries can increase the chances of harm from WBV.
4.0 How can monitoring be used to identify health risks and check control measures?
You must ensure, so far as is reasonably practicable,2 the health and safety of workers, and that other people are not put at risk by your work. In some circumstances, this could mean monitoring worker exposure and/or the health of workers.
Exposure monitoring measures and evaluates what your workers are being exposed to while they are at work.
Health monitoring looks at whether a worker’s health is being harmed because of what they are being exposed to while they are at work.
Monitoring should be carried out by a suitably qualified person with sufficient knowledge, skills, training and experience.
Monitoring is not a control measure. It does not replace the need for control measures to eliminate or minimise worker exposure to harm.
For more information about exposure monitoring and health monitoring, read our guidance: Exposure monitoring and health monitoring: Guidance for businesses
Exposure monitoring can be used to:
- identify, assess and confirm health risks
- identify where new control measures are needed
- monitor how well existing control measures are performing, and
- identify when control measures need to be reviewed, updated or removed.
Health monitoring can be used to monitor if workers are experiencing injury or illness from exposure.
As shown in Figure 2, monitoring information – along with verifying that your control measures are working effectively – can be used to continually improve how you are managing health risks.
For more information about managing risk, see Section 5.
When is it recommended to carry out exposure monitoring?
We recommend bringing in a competent person3 (such as an Occupational Hygienist) to assess the risk of WBV to your workers:
- if you are concerned that your workers may be at risk from WBV or
- if you are concerned you are exceeding the recommended values (Section 3).
If you exceed the exposure action value, we recommend:
- implementing control measures first to eliminate/minimise exposure levels (see Section 5 for guidance in this), and
- bringing in a competent person to measure the effectiveness of the control measures (see Section 6).
When is it recommended to carry out health monitoring?
We recommend setting up an early warning system to detect worker discomfort. Then if workers are experiencing discomfort, an assessment can be carried out to establish which work factors (including WBV) and/or non-work factors are causing it.
As described in Table 1, health monitoring is recommended:
- at the start of employment (to identify workers at increased risk, and to get baseline information)
- within six months of commencing work (to identify any early onset of symptoms) and then on a regular basis (for example, yearly).
We also recommend having a system so workers can report new or worsening symptoms to you during the time between the regular questionnaires.
What could exposure monitoring and health monitoring involve?
Table 1 shows examples of exposure monitoring and health monitoring.
|Exposure monitoring||Health monitoring|
|What does it involve?||
Exposure monitoring measures the amount of vibration workers are exposed to using measurement equipment in accordance with standards.
Measuring devices are placed on the seat pan, seat back or floor of the machine. The readings from these devices are then used to calculate the amount of vibration.
Results are measured against the exposure action value and exposure limits value. The risk to worker health is then assessed.
Health monitoring checks for lower back, neck or shoulder pain or other signs of discomfort.
Health monitoring could involve the following:
Note: Workers must give their informed consent(external link) for health monitoring. You must keep any personal information collected during monitoring secure and confidential, and use it for the purposes it has been collected for. For more information: Privacy Act 2020 principles(external link)
|Who carries it out?||
Exposure monitoring should be carried out by a competent person (or person under the supervision of a competent person), such as an Occupational Hygienist.
This person should have sufficient knowledge, skills, and experience in appropriate techniques and procedures, including the interpretation of results.
Health monitoring should be carried out by occupational health practitioners with relevant training, skills and experience in health monitoring.
From the assessments, a competent person can establish which work factors (including WBV) and/or non-work factor(s) are causing the discomfort.
As a result of this assessment, you will receive a recommendation as to whether the worker should continue to work with machines. You should follow this recommendation.
TABLE 1: Examples of WBV exposure monitoring and health monitoring
You should talk to a suitably qualified person with sufficient knowledge, skills, training and experience to confirm if monitoring is appropriate for you (and if so, what type and how often).
You must engage with workers and their representatives when making decisions about monitoring procedures (Appendix 4). Discuss with workers how exposure to excessive WBV can harm them, and how monitoring can be used to manage health risks.
For more information on monitoring, including setting up monitoring programmes and what to do if monitoring results show workers are being harmed or at risk, read our guidance: Exposure monitoring and health monitoring: Guidance for businesses
5.0 How can you manage the health and safety risks from excessive WBV?
If you need to manage the risks from excessive WBV, you could:
- reduce the amount of vibration workers are exposed to
- reduce the time workers are exposed to vibration (over each shift, over the time they work for you)
or ideally both.
You must work with other businesses you share monitoring duties with
You must work together with other PCBUs if you share health and safety duties (this could happen when you share a workplace or you are in a contracting chain). A shared duty could include managing shared risks (including those from WBV) or carrying out monitoring of the same worker. For more information about working with other businesses, see Appendix 3.
You must engage with your workers about health and safety matters
Seek the views of your workers and their representatives when identifying and assessing the risks from exposure to WBV, and when making decisions about the ways to eliminate or minimise those risks. For more information about engaging with workers, see Appendix 4.
What control measures could you consider?
You must first try to eliminate a risk so far as is reasonably practicable.
If it is not reasonably practicable to eliminate the risk, it must be minimised so far as is reasonably practicable.
You can use the hierarchy of control measures to help you to work out the most effective control measures to use.
Figure 3 describes control measures you could use to eliminate or minimise the risks arising from WBV. Multiple control measures may be needed to deal with a given risk. Give preference to control measures that protect many workers at the same time.
Put the control measures in place
As soon as possible after a decision is made about the control measures:
- put the control measures in place
- instruct and train workers (including new workers) about the control measures, including why it is important to use them and how to apply them.
6.0 When should you review and improve your WBV control measures?
Control measures should remain effective, and be fit-for-purpose, suitable for the nature and duration of the work, and used correctly.
With your workers, regularly monitor and review control measures to confirm that the measures are effective.
As discussed in Section 4, exposure monitoring can be used to monitor how well control measures are performing, and to identify when control measures need to be reviewed, updated or removed.
Get advice from a competent person on how often to monitor the effectiveness of control measures.
However you should immediately investigate, and review your WBV control
- the control measure does not control the risk, or
- a new hazard or risk is identified, or
- workers report potential early signs of harm from excessive WBV to you, or
- you receive exposure monitoring or health monitoring results that show your workers are being harmed or at risk from WBV (Section 4), or
- there will be a change in the workplace or work (for example, new equipment, new or changed work processes, increased workload, extended hours or additional/changed shifts), or
- your workers or their representatives indicate a review is necessary or request it.
Use the results of these reviews to continually improve how you manage health risks.
1. PCBUs have duties under the Health and Safety at Work Act 2015 (HSWA). For explanations of HSWA and more information about PCBUs, see Appendix 1.
2. See Appendix 2 for an explanation of what ‘so far as is reasonably practicable’ means.
3. A ‘competent person’ is someone who has sufficient knowledge, skills, training and experience in the appropriate techniques and procedures, including the interpretation of results – such as an Occupational Hygienist for exposure monitoring.