MSD Art Tool - Frequently asked questions
- Why is ART not suitable for use in DSE assessment?
- When should you use MAC and when should you use ART?
- Why doesn't ART consider the individual differences?
- How much force is a 'high force' or 'strong force'?
- What other tools or techniques are available to help determine the level of hand force?
- Why doesn't ART provide specific joint angles beyond which the posture should be considered awkward?
Why is ART not suitable for use in DSE assessment?
ART does not assess the frequency or repetition of finger movements, such as those involved in keyboard or mouse work. There are other methods that have been designed specifically for DSE assessment; for example, HSE's DSE workstation checklist. This will be better at pointing the way to risk reduction measures for DSE work.
When should you use MAC and when should you use ART?
There is no firm boundary to define when MAC should be used instead of ART. Instead, there is quite a bit of overlap in terms of when the two methods can be used.
However, it is important to know that a MAC assessment primarily focuses on risks to the lower back. An ART assessment primarily focuses on risks to the upper limbs.
Consider making a MAC assessment as well as an ART assessment where a repetitive task involves manual handling of loads weighing more than about 8kg.
The methods can identify common risk factors (such as reaching away from the body). However, they might also identify some different risk factors as well. Using both methods will ensure you have considered the risks to both the back and the upper limbs.
Why doesn't ART consider the individual differences?
ART does not include a separate risk factor for individual factors. However, individual differences are considered implicitly during an ART assessment. For example:
- The assessment of force and work pace risk factors requires you to speak to workers about how they perceive the work;
- The assessment of posture is influenced by differences in the size and shape of workers;
- The assessment of many factors will be influenced by differences in skill and competence.
To account for individual difference as much as possible, be sure to observe and speak to several workers of different size, age, level of experience, and level of skill.
How much force is a 'high force' or 'strong force'?
There is no simple answer because the level of force depends on many factors, including:
- The weight of an object;
- How the force is applied;
- The strength and capabilities of the person who applies the force;
- The physical properties that affect grip, such as the size and texture of the object and any gloves that are worn.
Other risk assessment checklists in the literature have used the following criteria to define a high level of force:
- Pinching an unsupported object weighing 2 pounds (about 1 kg) or more per hand, or using an equivalent pinching force
- Gripping an unsupported object weighing 10 pounds (about 4 kg) or more per hand, or using an equivalent gripping force
However, always confirm the level of force with the workers.
What other tools or techniques are available to help determine the level of hand force?
Sometimes it can be difficult to determine whether the hand force involved in the task is light, moderate, strong or very strong. There are other tools and techniques available to help make a more accurate assessment of the level of force exerted with each hand.
Borg CR10 Scale®
Some people may be familiar with the Borg CR10 Scale®. When using ART, the Borg CR10 Scale can also help determine the level of force exerted with each hand.
When using the Borg CR10 Scale:
- a rating of 2 or less corresponds to a light force on ART
- a rating of 3 or 4 corresponds to a moderate force
- a rating of 5 or 6 corresponds to a strong force
- a rating of 7 or more corresponds to a very strong force
More information on the design and use of the Borg CR10 Scale is found at the following link:
Why does ART not provide specific joint angles beyond which the posture should be considered awkward?
The assessment of awkward postures is intended to be a subjective assessment. Without measurement devices (eg goniometers), we must rely on observation and it is very difficult for us to make absolute judgements about joint angles for the upper limbs.
However, ISO 11228-3 (2007), "Ergonomics -- Manual handling -- Part 3: Handling of low loads at high frequency" ISBN 978 0 580 50582 9 does provide some joint angles beyond which upper limb posture is considered awkward.