CEA Ergonomic Tool & Equipment Selection 3 — Questions and Answers
Question 1: A dental hygienist reports thumb fatigue from hand scaling. Which instrument modification addresses the root cause?
- Switching to a heavier instrument for inertia assistance
- Using a large-diameter, textured, lightweight handle to reduce grip force (Correct answer)
- Adopting a shorter instrument to improve control
- Applying a rubber band wrap for cushioning
Correct answer: Using a large-diameter, textured, lightweight handle to reduce grip force
Large-diameter lightweight handles reduce the pinch and grip forces needed for control, directly addressing thumb and finger muscle fatigue in precision tasks.
Question 2: Which standard is MOST relevant when specifying the maximum vibration exposure allowed for operators of hand-held power tools?
- ANSI/ASSE Z365
- ISO 5349-1 for hand-arm vibration measurement (Correct answer)
- OSHA 29 CFR 1910.95 for noise
- NIOSH lifting equation
Correct answer: ISO 5349-1 for hand-arm vibration measurement
ISO 5349-1 specifies how to measure and report hand-arm vibration, providing the foundation for exposure limits and equipment selection decisions.
Question 3: When choosing a mouse for a user with carpal tunnel syndrome, which design feature is MOST protective?
- Wireless connectivity to reduce cable drag
- A vertical mouse that keeps the forearm in a pronation-neutral handshake position (Correct answer)
- Extra buttons for shortcut assignment
- Optical sensor for precision on multiple surfaces
Correct answer: A vertical mouse that keeps the forearm in a pronation-neutral handshake position
A vertical mouse holds the forearm in a neutral handshake orientation, eliminating forearm pronation and reducing pressure on the carpal tunnel.
Question 4: For overhead assembly tasks lasting more than 1 hour, which tool support system MOST reduces shoulder load?
- Lighter tool materials such as titanium alloy
- Counterbalance arm or spring balancer suspending the tool (Correct answer)
- Extended handle to keep elbows closer to the body
- Tool belt holster for quick retrieval
Correct answer: Counterbalance arm or spring balancer suspending the tool
A counterbalance arm or spring balancer offloads the tool's weight from the shoulder, dramatically reducing static muscle loading during overhead work.
Question 5: A quality inspector examines small parts under magnification for 6 hours daily. Which equipment addition MOST reduces neck strain?
- Brighter LED illumination for the inspection area
- A tilted workbench surface angled toward the user
- A binocular stereo microscope with adjustable stand positioned at eye level (Correct answer)
- Anti-fatigue matting to reduce leg fatigue
Correct answer: A binocular stereo microscope with adjustable stand positioned at eye level
A stereo microscope with an adjustable stand positioned at eye level allows inspection without sustained neck flexion, the primary driver of neck strain in this task.
Question 6: What is the primary ergonomic disadvantage of bent-handle tools compared to straight-handle tools in horizontal surface work?
- Bent handles weigh more due to additional material
- They restrict the range of force application angles
- They are designed for vertical, not horizontal, work orientations (Correct answer)
- Bent handles typically have smaller grip diameters
Correct answer: They are designed for vertical, not horizontal, work orientations
Bent-handle tools achieve wrist straightening in vertical work orientations; on horizontal surfaces a straight handle is already neutral, making bent handles counter-productive.
Question 7: For a nurse performing medication preparation at a medication cart, which cart feature MOST reduces low-back risk?
- Locking wheels to prevent cart movement
- Adjustable-height work surface positioned at elbow height (Correct answer)
- Stainless steel top for easy cleaning
- Modular drawer inserts for organization
Correct answer: Adjustable-height work surface positioned at elbow height
An adjustable-height surface set at the nurse's elbow height eliminates trunk flexion during preparation tasks, which is the primary low-back risk factor.
CEA Ergonomic Tool & Equipment Selection 3
A dental hygienist reports thumb fatigue from hand scaling.
Which instrument modification addresses the root cause?