Certified Safety Professional Exam Ergonomics and Human Factors 3 — Questions and Answers
Question 1: Which cognitive human factors concept explains why workers make errors even when they know the correct procedure?
- Skill-based behavior slips and lapses (Correct answer)
- Knowledge-based mistakes
- Violation of written procedures
- Fatigue-induced negligence
Correct answer: Skill-based behavior slips and lapses
Reason's GEMS model identifies slips and lapses as automatic, skill-based errors where the correct intention exists but execution fails due to distraction or habit.
Question 2: What is the recommended maximum sustained force for a pushing or pulling task to stay within acceptable ergonomic limits for most workers?
- 10 lbs initial/7 lbs sustained
- 50 lbs initial/35 lbs sustained (Correct answer)
- 100 lbs initial/75 lbs sustained
- 25 lbs initial/15 lbs sustained
Correct answer: 50 lbs initial/35 lbs sustained
NIOSH guidelines suggest push/pull initial forces up to 50 lbs and sustained forces up to 35 lbs for most workers performing occasional material handling tasks.
Question 3: In ergonomic risk assessment, what does the Strain Index (SI) specifically evaluate?
- Whole-body posture during lifting tasks
- Distal upper extremity disorders associated with hand-intensive jobs (Correct answer)
- Lower extremity fatigue in standing workers
- Spinal compressive forces during pulling tasks
Correct answer: Distal upper extremity disorders associated with hand-intensive jobs
The Strain Index assesses risk for distal upper extremity (hand, wrist, forearm) musculoskeletal disorders by evaluating intensity of exertion, duration, frequency, posture, pace, and duration per day.
Question 4: What is the relationship between keyboard height and carpal tunnel syndrome prevention?
- Higher keyboards reduce wrist extension strain
- Keyboards at or slightly below elbow height promote neutral wrist posture (Correct answer)
- Keyboard height has no effect on wrist position
- Wrist rests eliminate the need for proper keyboard height
Correct answer: Keyboards at or slightly below elbow height promote neutral wrist posture
Placing the keyboard at or slightly below elbow height allows the wrist to remain in a neutral, straight position, reducing stress on the carpal tunnel structures.
Question 5: Which ergonomic intervention is most appropriate when the weight of parts in an assembly task exceeds safe manual handling limits?
- Mandatory wrist braces for all workers
- Installation of mechanical assists such as balancers, hoists, or lift tables (Correct answer)
- Job rotation every 30 minutes
- Administrative limit of 2-hour maximum shifts
Correct answer: Installation of mechanical assists such as balancers, hoists, or lift tables
Engineering controls such as mechanical assists eliminate or reduce the manual handling load, addressing the root cause rather than relying on administrative or PPE controls.
Question 6: What is 'neutral posture' in ergonomics?
- The position in which a joint is at maximum extension
- The body position that places minimum stress on joints, muscles, and tendons (Correct answer)
- A completely relaxed, stationary body position
- The posture adopted during maximum-effort exertion
Correct answer: The body position that places minimum stress on joints, muscles, and tendons
Neutral posture keeps joints in their mid-range positions, minimizing musculoskeletal stress and reducing the risk of injury during prolonged or repetitive work.
Certified Safety Professional Exam Ergonomics and Human Factors 3
Which cognitive human factors concept explains why workers make errors even when they know the correct procedure?