SAF Workplace Ergonomics & Health 3 — Questions and Answers
Question 1: In NIOSH's revised lifting equation, what does the Recommended Weight Limit (RWL) represent?
- The maximum weight any worker may ever lift
- The weight a healthy worker can lift over an 8-hour shift without elevated risk of low-back injury (Correct answer)
- The weight limit set by OSHA for all manual handling tasks
- The average load handled during a workday
Correct answer: The weight a healthy worker can lift over an 8-hour shift without elevated risk of low-back injury
The RWL is the load a healthy worker can lift repeatedly under specified task conditions without substantially increasing the risk of low-back disorder.
Question 2: What does a Lifting Index (LI) value greater than 3.0 indicate according to NIOSH guidelines?
- The task is safe for all workers
- Minor ergonomic concerns that should be monitored
- Significant risk; the task should be redesigned immediately (Correct answer)
- The task requires only a lumbar support belt
Correct answer: Significant risk; the task should be redesigned immediately
An LI above 3.0 represents a substantially elevated risk of low-back injury and requires immediate ergonomic redesign of the lifting task.
Question 3: Which of the following best describes 'contact stress' as an ergonomic risk factor?
- Stress caused by interpersonal conflict at work
- Pressure on soft tissue from a hard edge or surface during work tasks (Correct answer)
- Thermal stress from hot or cold contact surfaces
- Mental stress from customer-facing roles
Correct answer: Pressure on soft tissue from a hard edge or surface during work tasks
Contact stress occurs when a hard edge (e.g., desk edge, tool handle) presses on soft tissue, restricting blood flow and compressing nerves.
Question 4: A forklift operator reports lower back pain that worsens during the work shift. Which ergonomic hazard is the PRIMARY contributor?
- Awkward posture from seat adjustment
- Whole-body vibration (WBV) transmitted through the vehicle seat (Correct answer)
- Repetitive finger motion on controls
- Contact stress from the steering wheel
Correct answer: Whole-body vibration (WBV) transmitted through the vehicle seat
Whole-body vibration from industrial vehicles is a well-established risk factor for lumbar spine disorders among forklift and heavy equipment operators.
Question 5: When performing a workstation assessment, which tool uses a systematic body-part scoring method to estimate postural risk levels for upper limbs?
- NIOSH Lifting Equation
- RULA (Rapid Upper Limb Assessment) (Correct answer)
- Snook Tables
- JSI (Job Strain Index)
Correct answer: RULA (Rapid Upper Limb Assessment)
RULA evaluates postures of the neck, trunk, and upper limbs using scored body-part diagrams to produce an overall risk level.
Question 6: What is the primary purpose of an anti-fatigue mat in a standing workstation?
- To prevent slip-and-fall incidents only
- To reduce static muscle loading in the legs and lower back by encouraging micro-movements (Correct answer)
- To provide insulation from cold concrete floors only
- To delineate safe walking zones in a warehouse
Correct answer: To reduce static muscle loading in the legs and lower back by encouraging micro-movements
Anti-fatigue mats reduce discomfort and musculoskeletal fatigue by promoting subtle shifting of weight and stimulating leg muscle contractions.
Question 7: According to ergonomics best practices, the top of a computer monitor should be positioned at or slightly below which anatomical reference point?
- Top of the user's head
- Eye level (Correct answer)
- Chin level
- Shoulder level
Correct answer: Eye level
Placing the monitor top at eye level minimizes neck flexion and extension, keeping the cervical spine in a neutral position.
SAF Workplace Ergonomics & Health 3
In NIOSH's revised lifting equation, what does the Recommended Weight Limit (RWL) represent?