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| MODULE: INTRODUCTION TO ERGONOMICS |
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The Rapid Upper Limb Assessment (RULA) is an ergonomic technique used to evaluate exposures to posture, forces and muscle activities that have been shown to contribute to repetitive strain injuries. The ergonomic evaluation results in a risk score between one and seven, where higher scores signify greater levels of apparent risk.
The RULA tool was developed to detect work postures or risk factors that need further attention. This tool requires no equipment and provides a quick assessment of the postures of the neck, trunk and upper limbs along with muscle function and the external loads experienced by the body. A coding system is used to generate an action score, which indicates the level of loading experienced by the different body parts. The final score is then used as a guideline for the level of intervention required to reduce the risks of injury due to physical loading on the operator. The risk factors assessed are external load factors which include the number of movements, static muscle work, force, work posture determined by the equipment and time worked without a break.
Links to the form and RULA tool are as follows:
http://ergo.human.cornell.edu/Pub/AHquest/CURULA.pdf
http://www.ergonomics.co.uk/Rula/Ergo/index.html
Example of Ergonomic risk assessment: the Rapid Upper Limb Assessment (RULA) technique was used to assess the tablet packaging task of filling blisters.
See also this link for other tools: Analysis Tools for Ergonomists
Vibrating hand tools transmit vibrations to the holder and depending on the vibration level and duration factors, may contribute to Raynaud’s syndrome or vibration induced white finger disorders (hand-arm vibration syndrome).
The Specific Performance Approach to analyzing vibration can be found on page 6 of the Hazard Zone Checklist*. This simple method bypasses the need to measure the vibration transmitted to the hand. It depends on the vibration reported by the manufacturer and is only as accurate as their claimed value. Care should be taken in using such values since they may be measurements taken under favourable conditions.
A task cycle time of less that 30 sec has been considered as "repetitive". Motions performed every few seconds may produce fatigue and muscle-tendon strain. Without sufficient recovery, time for repair there is an increased risk of tissue damage.
How much is too much? There is no consensus at to what repetition rates increase the risk factor for MSDs. Tray 6-B is a possible guideline published by A. Kilbom.
| Body Part | Repetitions per minute |
|---|---|
| Shoulder | More than 2½ |
| Upper arm/elbow | More than 10 |
| Forearm/wrist | More than 10 |
| Finger | More than 200 |
| From Kilbom, A. Repetitive work of the upper extremity; Part II; The scientific basis for the guide: Int,.J. Ind. Erg. 14 59-86 | |
Frequency and duration of exposure from "Cumulative trauma disorders of the upper extremities" by Anil Mital state that:
Proactive ergonomics:NIOSH- Elements of an Ergonomics Programme Tray 9 A - 9F
Evaluating control effectiveness: Examples from the NIOSH - Elements of an Ergonomics programmes Tray 7 A - B.
* Permission pending
