COHN Ergonomics and Physical Hazards 3 — Questions and Answers
Question 1: A construction worker is exposed to whole-body vibration from operating a jackhammer daily. The primary long-term health risk is:
- Noise-induced hearing loss
- Low back degeneration and disc disorders (Correct answer)
- Occupational asthma
- Contact dermatitis
Correct answer: Low back degeneration and disc disorders
Prolonged whole-body vibration is strongly associated with accelerated lumbar disc degeneration, low back pain, and spinal disorders.
Question 2: The Rapid Upper Limb Assessment (RULA) tool generates a grand score. A score of 7 indicates:
- Acceptable posture; investigate only if discomfort is reported
- Further investigation and change soon
- Immediate investigation and implementation of change (Correct answer)
- Low risk; no action required
Correct answer: Immediate investigation and implementation of change
A RULA grand score of 7 (the maximum) indicates the highest action level, requiring immediate investigation and ergonomic change.
Question 3: When assessing thermal stress in a hot outdoor environment, which index accounts for humidity, radiant heat, and air movement?
- Heat index
- Wet Bulb Globe Temperature (WBGT) (Correct answer)
- Discomfort index
- Apparent temperature
Correct answer: Wet Bulb Globe Temperature (WBGT)
WBGT integrates dry bulb, wet bulb, and globe temperature readings to reflect the combined thermal stress of humidity, radiation, and air movement on a worker.
Question 4: A COHN is designing a workstation for data entry. The recommended elbow angle for keyboard use to minimize upper extremity strain is approximately:
- 45–60 degrees
- 70–90 degrees (Correct answer)
- 100–120 degrees
- 130–150 degrees
Correct answer: 70–90 degrees
A 90-degree (roughly neutral) elbow angle with the forearm parallel to the floor minimizes static load on shoulder and forearm muscles during keyboard tasks.
Question 5: Which of the following best describes the purpose of a job hazard analysis (JHA) in an ergonomics program?
- To calculate the workers' compensation premium
- To systematically identify ergonomic risk factors for each job task (Correct answer)
- To document worker medical histories
- To determine PPE reimbursement procedures
Correct answer: To systematically identify ergonomic risk factors for each job task
A JHA breaks each job into tasks and analyzes the ergonomic risk factors (force, repetition, posture, vibration, contact stress) associated with each task.
Question 6: Laser radiation in the workplace is classified by Class. A Class 3B laser poses primary risk to which tissue?
- Skin only
- Eyes only, with hazardous diffuse reflections possible
- Both eyes and skin from direct beam only (Correct answer)
- No tissue risk; Class 3B is non-hazardous
Correct answer: Both eyes and skin from direct beam only
Class 3B lasers are hazardous to the eye and skin from direct beam and specular reflections, but diffuse reflections are generally not hazardous.
Question 7: A nurse reports tingling and numbness in the thumb, index, and middle fingers that worsens at night. The COHN suspects carpal tunnel syndrome. The most appropriate next action is:
- Immediately reassign the nurse to a non-clinical role
- Refer for medical evaluation and nerve conduction study (Correct answer)
- Issue wrist splints without further evaluation
- Document the complaint and monitor without intervention
Correct answer: Refer for medical evaluation and nerve conduction study
Referral for formal medical evaluation, including nerve conduction studies, is the appropriate step to confirm the diagnosis before initiating treatment or job modification.
COHN Ergonomics and Physical Hazards 3
A construction worker is exposed to whole-body vibration from operating a jackhammer daily.
The primary long-term health risk is: