RSS Industrial Hygiene 1 — Questions and Answers
Question 1: What does TLV-TWA stand for in industrial hygiene?
- Time-Limit Value - Total Workplace Average
- Toxic Level Verification - Time-Weighted Analysis
- Threshold Limit Value - Time-Weighted Average (Correct answer)
- Toxic Limit Value - Total Work Assessment
Correct answer: Threshold Limit Value - Time-Weighted Average
TLV-TWA (Threshold Limit Value - Time-Weighted Average) is the ACGIH-defined concentration for a normal 8-hour workday and 40-hour workweek to which workers may be repeatedly exposed without adverse effects.
Question 2: Which sequence correctly describes the industrial hygiene paradigm?
- Control, Evaluate, Recognize
- Recognize, Evaluate, Control (Correct answer)
- Evaluate, Recognize, Control
- Recognize, Control, Evaluate
Correct answer: Recognize, Evaluate, Control
The industrial hygiene paradigm follows Recognize, Evaluate, and Control — you must first identify a hazard, then assess its magnitude, before implementing controls.
Question 3: OSHA's Permissible Exposure Limit (PEL) for occupational noise is:
- 85 dBA as an 8-hour TWA
- 90 dBA as an 8-hour TWA (Correct answer)
- 95 dBA as an 8-hour TWA
- 100 dBA as an 8-hour TWA
Correct answer: 90 dBA as an 8-hour TWA
OSHA's PEL for occupational noise exposure under 29 CFR 1910.95 is 90 dBA as an 8-hour time-weighted average.
Question 4: Which type of ventilation captures contaminants at their source before they disperse into the work environment?
- General dilution ventilation
- Natural ventilation
- Local exhaust ventilation (Correct answer)
- Supply air ventilation
Correct answer: Local exhaust ventilation
Local exhaust ventilation (LEV) captures contaminants at or near their point of generation, preventing them from entering the workplace atmosphere.
Question 5: ACGIH Biological Exposure Indices (BEIs) are used to:
- Set maximum airborne chemical concentrations
- Evaluate biological monitoring results from worker specimens (Correct answer)
- Determine the lethal dose for 50% of a test population
- Establish minimum detectable concentrations for air samples
Correct answer: Evaluate biological monitoring results from worker specimens
BEIs are reference values for evaluating biological monitoring results, representing determinant levels expected in specimens from healthy workers exposed at the TLV.
Question 6: The term 'LD50' in toxicology refers to:
- The lethal dose that kills 50% of a test population (Correct answer)
- The lowest documented dose causing 50% organ impairment
- The lethal duration of 50 minutes at maximum concentration
- The lethal dose for 5% of subjects, scaled by a factor of 10
Correct answer: The lethal dose that kills 50% of a test population
LD50 (Lethal Dose 50) is the amount of a substance required to kill 50% of a test animal population, used as a standard measure of acute toxicity.
Question 7: Which sampling strategy provides the most accurate full-shift TWA exposure assessment?
- Grab sampling
- Short-term exposure limit sampling
- Full-period consecutive sampling (Correct answer)
- Peak concentration sampling
Correct answer: Full-period consecutive sampling
Full-period consecutive sampling collects the air sample throughout the entire work shift with no gaps, providing the most accurate time-weighted average exposure.
RSS Industrial Hygiene 1
What does TLV-TWA stand for in industrial hygiene?