RSS Industrial Hygiene 2 — Questions and Answers
Question 1: When conducting personal air monitoring, the sampling device should be positioned:
- On the worker's belt near the waist
- Within 12 inches of the nose and mouth (breathing zone) (Correct answer)
- On the worker's wrist to minimize pump interference
- At workstation height, away from the worker's body
Correct answer: Within 12 inches of the nose and mouth (breathing zone)
Personal air samples must be collected in the breathing zone — within 12 inches of the nose and mouth — to accurately represent the air a worker actually inhales.
Question 2: Which instrument is most appropriate for real-time monitoring of oxygen levels in a confined space?
- Colorimetric detector tube
- Passive diffusion dosimeter
- Direct-reading electrochemical oxygen meter (Correct answer)
- High-volume integrated air sampler
Correct answer: Direct-reading electrochemical oxygen meter
A direct-reading electrochemical oxygen meter provides immediate, continuous measurement of oxygen levels, which is essential for confined space entry decisions.
Question 3: Under OSHA's Noise Standard, the action level that triggers a Hearing Conservation Program is:
- 80 dBA TWA
- 85 dBA TWA (Correct answer)
- 90 dBA TWA
- 95 dBA TWA
Correct answer: 85 dBA TWA
OSHA requires employers to implement a Hearing Conservation Program when worker noise exposures equal or exceed 85 dBA as an 8-hour TWA — the action level.
Question 4: A noise dosimeter reading of 100% corresponds to exposure at:
- 85 dBA for 8 hours
- 90 dBA for 8 hours (Correct answer)
- 95 dBA for 8 hours
- 100 dBA for 8 hours
Correct answer: 90 dBA for 8 hours
A 100% noise dose equals exactly the OSHA PEL of 90 dBA for 8 hours; any reading above 100% indicates an overexposure.
Question 5: Wipe sampling in industrial hygiene is primarily used to assess:
- Airborne particle concentrations
- Surface contamination with hazardous substances (Correct answer)
- Biological metabolite levels in worker urine
- Respiratory protection fit and seal effectiveness
Correct answer: Surface contamination with hazardous substances
Wipe (surface) sampling quantifies contamination on work surfaces with substances such as heavy metals, pesticides, or biological agents.
Question 6: The Wet Bulb Globe Temperature (WBGT) index is primarily used to evaluate:
- Chemical vapor concentration in hot environments
- Heat stress risk to workers (Correct answer)
- Humidity levels in cleanroom facilities
- Thermal comfort in office settings
Correct answer: Heat stress risk to workers
WBGT is the most widely accepted occupational index for assessing heat stress, as it accounts for humidity, radiant heat, and air movement simultaneously.
Question 7: In air sampling, the minimum quantifiable concentration (MQC) represents:
- The highest concentration accurately measurable by the method
- The lowest concentration that can be reliably quantified by the analytical method (Correct answer)
- The concentration at which acute health effects are first observed
- The average background concentration found in uncontrolled environments
Correct answer: The lowest concentration that can be reliably quantified by the analytical method
The MQC is the lowest airborne concentration that can be reliably and accurately quantified using the specific sampling and analytical method employed.
RSS Industrial Hygiene 2
When conducting personal air monitoring, the sampling device should be positioned: