CIEE Environmental Factors & Human Performance 5

Question 1

A night-shift worker's reaction time is tested at 3 AM and found to be 18% slower than their baseline. Which environmental intervention would most directly counteract this circadian performance trough?

Accepted Answer

Bright light exposure (>2,500 lux) in the first half of the night shift to suppress melatonin and shift circadian phase

Answer

High-intensity bright light during the night shift suppresses melatonin and phase-shifts the circadian clock, improving alertness and reaction time during the biological night.

Question 2

Which approach should an ergonomist use to evaluate 'combined exposure' when workers experience both noise above 85 dBA and whole-body vibration above 0.5 m/s²?

Accepted Answer

Assess each stressor against its own limit and consider synergistic musculoskeletal and auditory risks from simultaneous exposure

Answer

Current standards require independent assessment against each stressor's limit, but ergonomic evaluation must also consider synergistic effects such as vibration-aggravated tinnitus and noise-distracted postural instability.

Question 3

A food processing plant operates at 10°C (50°F). Workers perform standing tasks on concrete floors for 8-hour shifts. Which environmental modification most reduces cold-related musculoskeletal fatigue?

Accepted Answer

Installing anti-fatigue matting with thermal insulation rated for cold environments

Answer

Thermally insulating anti-fatigue matting breaks conductive heat loss through the feet to the cold floor and reduces static leg muscle loading simultaneously, addressing two cold-environment ergonomic hazards.

Question 4

In a measurement of indoor air quality, which variable is most directly linked to Sick Building Syndrome (SBS) symptoms that reduce sustained attention and increase error rates?

Accepted Answer

Total Volatile Organic Compounds (TVOCs) above 300 µg/m³ combined with CO2 above 1,000 ppm

Answer

The combination of elevated TVOC levels from off-gassing materials and CO2 accumulation from inadequate ventilation is most consistently associated with SBS-related cognitive symptoms in office environments.

Question 5

A quality control inspector performs color-critical tasks matching paint samples. Which lighting specification is most important to specify for this workstation?

Accepted Answer

Color Rendering Index (CRI) ≥ 95 with correlated color temperature (CCT) matched to evaluation standard (typically D65, 6500K)

Answer

Color-matching tasks require CRI ≥ 95 (ideally Ra 95–100) under a standardized illuminant (D65) to ensure accurate color perception; other parameters are secondary for color-critical inspection.

(CIEE) Certified Industrial Ergonomic Evaluator Practice Test

(CIEE) Certified Industrial Ergonomic Evaluator Practice Test

CIEE Environmental Factors & Human Performance 5