Ergonomics and manual handling
What this domain tests
This domain - ergonomics and manual handling - tests how work is fitted to people: posture, force, repetition, duration and recovery, and the assessment of manual handling and display screen work. Questions often ask whether a lifting task is acceptable or which control changes risk most.
Core rules
- MSD risk factors. Force, awkward posture, repetition, vibration, contact stress and insufficient recovery interact. Duration multiplies risk.
- Assessment tools. The NIOSH lifting equation estimates a recommended weight limit for two-handed manual lifting under defined assumptions. RULA and REBA screen postures but do not by themselves prescribe controls. Anthropometric data help set work heights and reaches.
- Manual handling controls. Eliminate handling, mechanise, reduce load weight and size, improve grip, adjust height, reduce carrying distance, and plan team lifting only when coordinated.
- Display screen equipment. Adjust chair, screen height, keyboard, mouse, lighting and breaks; encourage posture variation rather than one perfect posture.
- Worker involvement. Workers know the actual task; their input exposes awkward reaches, poor grips and workarounds that observation alone misses.
Worked example
A two-handed lift has a 15 kg load, horizontal distance 30 cm, vertical height 75 cm, vertical travel 50 cm, frequency 1 lift per minute, no asymmetry and a good grip. The NIOSH recommended weight limit is 23 x (25/30) x (1 - 0.003|75-75|) x (0.82 + 4.5/50) x 1 x 0.75 x 1. That is 23 x 0.833 x 1 x 0.91 x 1 x 0.75 x 1, about 13.1 kg. The lifting index is 15/13.1, about 1.14, so the task exceeds the recommended limit. The best control is to reduce the load or raise the pick-up height, not merely to instruct workers to bend their knees.
Traps that cost marks
- Treating RULA or REBA as a control measure rather than a screening tool.
- Applying NIOSH outside its assumptions, such as one-handed or seated lifts.
- Ignoring frequency, duration and recovery time.
- Assuming team lifting halves individual risk.
- Adjusting only the chair and ignoring task design.
- Recording a posture score without the exposure duration.