CIH - Certified Industrial Hygienist Ergonomics and Biomechanics Questions and Answers — Questions and Answers
Question 1: Which of the following is the BEST example of an engineering control implemented to mitigate ergonomic risk factors for an assembly line worker?
- Installing an articulating arm to hold a heavy power tool. (Correct answer)
- Providing annual training on proper lifting techniques.
- Supplying workers with anti-vibration gloves.
- Implementing a job rotation schedule to vary tasks.
Correct answer: Installing an articulating arm to hold a heavy power tool.
An engineering control is a physical modification to the workplace, equipment, or process that eliminates or reduces the hazard. An articulating arm physically supports the tool's weight, removing the static load and awkward posture stress from the worker. Training and job rotation are administrative controls, while gloves are personal protective equipment (PPE).
Question 2: A data entry clerk reports numbness and tingling in their thumb, index, and middle finger after several months of working with their wrists bent upwards in extension. This symptomology is most characteristic of which of the following nerve-related cumulative trauma disorders?
- Thoracic Outlet Syndrome
- Carpal Tunnel Syndrome (Correct answer)
- Raynaud's Syndrome
- Ulnar Nerve Entrapment
Correct answer: Carpal Tunnel Syndrome
Carpal Tunnel Syndrome (CTS) is caused by the compression of the median nerve as it passes through the carpal tunnel in the wrist. The median nerve provides sensation to the thumb, index, middle, and half of the ring finger. Sustained wrist extension increases pressure within the carpal tunnel, leading to CTS symptoms.
Question 3: In a biomechanical analysis of the arm, the elbow acts as the fulcrum. A worker holds a 15 lb tool in their hand, which is 14 inches from the elbow. If the biceps muscle, providing the effort, inserts 2 inches from the elbow, what is the approximate force the biceps must exert to hold the tool steady?
- 30 lbs
- 15 lbs
- 105 lbs (Correct answer)
- 210 lbs
Correct answer: 105 lbs
The forearm acts as a Class 3 lever. The principle of moments states that Effort Force × Effort Arm = Load Force × Load Arm. In this case: (Biceps Force × 2 inches) = (15 lbs × 14 inches). Solving for the Biceps Force gives (15 × 14) / 2 = 210 / 2 = 105 lbs.
Question 4: The Revised NIOSH Lifting Equation is a primary tool used by industrial hygienists to assess the risk of injury for specific tasks. Its application is MOST appropriate for which of the following scenarios?
- Evaluating a worker pushing a heavy cart up a ramp.
- Assessing a seated worker repetitively assembling small parts.
- Analyzing a warehouse worker carrying a box from one pallet to another.
- Calculating the risk for a worker lifting a crate from the floor to a shelf with both hands. (Correct answer)
Correct answer: Calculating the risk for a worker lifting a crate from the floor to a shelf with both hands.
The Revised NIOSH Lifting Equation is specifically designed to assess the risk of low-back injury associated with two-handed manual lifting and lowering tasks. It does not apply to one-handed lifts, carrying, pushing, pulling, or seated work.
Question 5: An industrial hygienist is helping design a new workstation console for a control room that must accommodate a wide range of employees. To ensure all operators can reach a critical emergency shutoff button, the maximum allowable reach distance should be based on which anthropometric value?
- 5th percentile female forward reach (Correct answer)
- 95th percentile male forward reach
- 50th percentile (average) male forward reach
- Average of 5th percentile female and 95th percentile male reach
Correct answer: 5th percentile female forward reach
When designing for reach, the principle is to accommodate the smallest user. Using the 5th percentile female forward reach ensures that 95% of the female population and virtually all of the male population can access the control. Using a larger percentile would place the button out of reach for smaller operators.
Question 6: The Rapid Upper Limb Assessment (RULA) is an ergonomic assessment tool used to screen for risk factors associated with musculoskeletal disorders. The primary focus of the RULA tool is evaluating:
- The metabolic load and heat stress of a task.
- Whole-body exposure to vibration.
- Lower back stress during two-handed manual lifting.
- Postural stress on the neck, trunk, and upper extremities. (Correct answer)
Correct answer: Postural stress on the neck, trunk, and upper extremities.
RULA, or Rapid Upper Limb Assessment, is a screening tool specifically designed to evaluate the exposure of workers to ergonomic risk factors associated with upper extremity musculoskeletal disorders. It assesses the posture of the neck, trunk, and upper limbs (shoulders, elbows, wrists) along with muscle use and force.
CIH - Certified Industrial Hygienist Ergonomics and Biomechanics Questions and Answers
Which of the following is the BEST example of an engineering control implemented to mitigate ergonomic risk factors for an assembly line worker?