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Environmental Ergonomics Flashcards

7 cards from real CES practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which lighting measure describes the total amount of luminous flux (light) incident on a surface per unit area, and is the primary metric used to evaluate workplace lighting adequacy?

    Answer: Illuminance (lux or foot-candles)

    Illuminance (measured in lux or foot-candles) quantifies the light falling on a work surface and is the standard metric for workplace lighting design compliance.

  2. An ergonomist conducting a vibration assessment measures a hand-arm vibration frequency-weighted acceleration of 4 m/s². According to the EU Vibration Directive, what is the maximum daily exposure time before reaching the exposure limit value (ELV) of 5 m/s² A(8)?

    Answer: 3.1 hours

    Using the A(8) formula, at 4 m/s² the worker reaches the 5 m/s² ELV in approximately 3.1 hours of daily exposure.

  3. In the context of environmental ergonomics, what does the term 'luminance ratio' refer to?

    Answer: The difference in brightness between a task and its immediate surround

    Luminance ratio describes the brightness difference between adjacent visual areas (e.g., task vs. surround); excessively high ratios cause eye strain and visual fatigue.

  4. Carbon dioxide (CO₂) concentration in indoor air is used as an indirect indicator of:

    Answer: Ventilation adequacy and occupant-generated bioeffluents

    CO₂ rises as occupants exhale and falls when fresh air is introduced, making it a practical proxy for measuring whether ventilation is adequate to dilute human bioeffluents.

  5. When assessing noise exposure in a mixed-noise environment where a worker is exposed to different levels for different durations, which calculation method should the ergonomist apply?

    Answer: Dose summation formula (C₁/T₁ + C₂/T₂ + … ≤ 1)

    The noise dose summation formula (Σ Cᵢ/Tᵢ ≤ 1) combines exposures at different levels by expressing each as a fraction of the allowable time, ensuring total dose does not exceed 100%.

  6. Which personal protective approach is considered a last resort in the hierarchy of controls for managing environmental stressors such as extreme heat or noise?

    Answer: Personal protective equipment (cooling vests, earplugs)

    PPE is at the bottom of the hierarchy of controls because it relies on worker compliance and does not reduce the hazard at its source, unlike elimination or engineering controls.

  7. A worker's primary complaint is visual fatigue and headaches after using a computer workstation. The ergonomist identifies a luminance ratio of 10:1 between the screen and the dark background wall behind it. What is the most appropriate corrective action?

    Answer: Add indirect or background lighting to raise the surround luminance and reduce the ratio

    Raising surround luminance with indirect or ambient lighting reduces the brightness contrast between screen and background, lowering the luminance ratio and reducing eye strain.