CEA Industrial Ergonomics 3 — Questions and Answers
Question 1: Which factor does the ACGIH Hand Activity Level (HAL) TLV primarily quantify?
- Peak hand force only
- Combined hand activity frequency and exertion pattern (Correct answer)
- Total weight handled per shift
- Duration of grip contact per day
Correct answer: Combined hand activity frequency and exertion pattern
The HAL TLV is based on the frequency of hand motions and duty cycle (exertion-to-rest ratio) to characterize repetitive hand/wrist exposure.
Question 2: A worker experiences hand-arm vibration while operating a grinder. Which health outcome is specifically associated with this exposure?
- Raynaud's phenomenon (vibration white finger) (Correct answer)
- Trigger finger
- Lateral epicondylitis
- Dupuytren's contracture
Correct answer: Raynaud's phenomenon (vibration white finger)
Prolonged hand-arm vibration exposure can cause vibration white finger (VWF), a form of Raynaud's phenomenon involving vascular and neurological damage.
Question 3: In the RULA (Rapid Upper Limb Assessment) method, a score of 7 indicates:
- Acceptable posture, no change needed
- Further investigation may be needed
- Investigate and implement changes soon
- Implement changes immediately (Correct answer)
Correct answer: Implement changes immediately
A RULA grand score of 7 is the highest level, indicating the posture is unacceptable and changes must be implemented immediately.
Question 4: Which design change BEST reduces shoulder loading for overhead assembly work?
- Increasing the grip force required for tools
- Lowering the work surface to increase reach distance
- Using articulating arms or lift assists to bring parts to elbow height (Correct answer)
- Extending shift duration to reduce daily work pace
Correct answer: Using articulating arms or lift assists to bring parts to elbow height
Articulating arms or positioning systems that bring work to elbow height eliminate overhead reach, dramatically reducing deltoid and shoulder muscle loading.
Question 5: What is 'dead man's hand' or 'trigger finger' most associated with in industrial ergonomics?
- Sustained whole-body vibration from forklifts
- Repetitive or sustained flexion of finger tendons combined with high grip force (Correct answer)
- Cold temperature exposure to the lower extremities
- Static elbow flexion beyond 90 degrees
Correct answer: Repetitive or sustained flexion of finger tendons combined with high grip force
Trigger finger (stenosing tenosynovitis) results from repetitive forceful gripping causing tendon sheath inflammation, making finger flexion catching or locking.
Question 6: In ergonomic load assessment, 'moment arm' refers to:
- Duration of lifting during a shift
- Perpendicular distance from the load to the joint's axis of rotation (Correct answer)
- The maximum weight a worker can safely carry
- The time between consecutive lifts
Correct answer: Perpendicular distance from the load to the joint's axis of rotation
Moment arm is the perpendicular distance from the applied force (load) to the joint center, determining torque; a longer moment arm creates greater joint loading.
Question 7: Which ergonomic control is MOST effective for reducing whole-body vibration in forklift operators?
- Providing anti-vibration gloves
- Installing a suspension seat with proper damping characteristics (Correct answer)
- Scheduling more frequent breaks without equipment changes
- Requiring operators to stand rather than sit while driving
Correct answer: Installing a suspension seat with proper damping characteristics
A properly tuned suspension seat with matched damping attenuates vibration at the seat-operator interface, reducing transmission to the lumbar spine.
CEA Industrial Ergonomics 3
Which factor does the ACGIH Hand Activity Level (HAL) TLV primarily quantify?