OHST Industrial Hygiene & Exposure Assessment 1 — Questions and Answers
Question 1: What does the acronym TLV-TWA stand for in industrial hygiene?
- Threshold Limit Value - Time-Weighted Average (Correct answer)
- Total Level Value - Time-Weighted Assessment
- Toxic Limit Value - Time-Weighted Average
- Threshold Level Variable - Time-Weighted Amount
Correct answer: Threshold Limit Value - Time-Weighted Average
TLV-TWA stands for Threshold Limit Value - Time-Weighted Average, representing the average airborne concentration for a normal 8-hour workday published by ACGIH.
Question 2: Which organization publishes Permissible Exposure Limits (PELs) that are legally enforceable in U.S. workplaces?
- ACGIH
- NIOSH
- OSHA (Correct answer)
- EPA
Correct answer: OSHA
OSHA publishes PELs as legally enforceable federal standards under the Occupational Safety and Health Act.
Question 3: What is the purpose of the Short-Term Exposure Limit (STEL)?
- To establish the maximum allowable concentration over an 8-hour workday
- To set the maximum concentration for a 15-minute period not to be exceeded (Correct answer)
- To define the concentration immediately dangerous to life or health
- To specify the minimum detectable concentration of a substance
Correct answer: To set the maximum concentration for a 15-minute period not to be exceeded
The STEL is the maximum concentration to which workers can be exposed for up to 15 minutes without suffering acute adverse effects.
Question 4: The designation 'IDLH' in industrial hygiene represents a concentration that is:
- Immediately Dangerous to Life or Health (Correct answer)
- Indirectly Damaging to Lung Health
- Immediately Detectable at Low Hazard levels
- Intermittently Dangerous at Low Heights
Correct answer: Immediately Dangerous to Life or Health
IDLH (Immediately Dangerous to Life or Health) is a NIOSH value representing the maximum concentration from which one could escape without irreversible health effects.
Question 5: Which route of entry is typically the primary concern for most airborne industrial chemicals?
- Dermal absorption
- Ingestion
- Inhalation (Correct answer)
- Eye contact
Correct answer: Inhalation
Inhalation is the primary exposure route for airborne chemicals because the lungs provide a large surface area and rapid transfer into the bloodstream.
Question 6: An industrial hygienist conducting a 'worst-case' exposure assessment assumes:
- Exposures during the least demanding work tasks
- Average exposures across all routine job tasks
- Maximum anticipated exposures under the most demanding work conditions (Correct answer)
- Minimum detectable exposure levels for regulatory comparison
Correct answer: Maximum anticipated exposures under the most demanding work conditions
Worst-case assessments evaluate peak exposures under the most demanding conditions to ensure controls remain protective even at maximum foreseeable levels.
Question 7: What is the primary purpose of an Occupational Exposure Limit (OEL)?
- To establish legal penalties for employers who exceed exposure standards
- To protect nearly all workers from adverse health effects with repeated daily exposure (Correct answer)
- To define the minimum concentration at which any detectable harm occurs
- To set production quotas for manufacturers of hazardous chemicals
Correct answer: To protect nearly all workers from adverse health effects with repeated daily exposure
OELs are designed to protect the vast majority of workers from adverse health effects when exposed repeatedly over an entire working lifetime.
OHST Industrial Hygiene & Exposure Assessment 1
What does the acronym TLV-TWA stand for in industrial hygiene?