HSE Occupational Health and Industrial Hygiene 5 — Questions and Answers
Question 1: Which ACGIH exposure limit category represents a concentration that should not be exceeded even instantaneously?
- Ceiling (C) (Correct answer)
- TLV-TWA
- TLV-STEL
- Excursion limit
Correct answer: Ceiling (C)
The ACGIH Ceiling (C) value is the concentration that should never be exceeded at any time during the workday, regardless of how brief the exposure.
Question 2: A new chemical process introduces hydrogen sulfide gas. Workers report detecting a rotten egg odor during startup, then losing the ability to smell it. What phenomenon explains this?
- Olfactory fatigue (odor paralysis) (Correct answer)
- Habituation to background odors
- Oxidation of the odorant by nasal enzymes
- Inadequate concentration to stimulate olfactory receptors
Correct answer: Olfactory fatigue (odor paralysis)
Hydrogen sulfide rapidly paralyzes the olfactory nerve at concentrations above about 100 ppm, causing workers to lose the warning signal precisely when danger is greatest.
Question 3: Under OSHA's hearing conservation program (29 CFR 1910.95), at what action level must employers enroll workers in annual audiometric testing?
- 85 dBA TWA (Correct answer)
- 90 dBA TWA
- 80 dBA TWA
- 95 dBA TWA
Correct answer: 85 dBA TWA
OSHA requires employers to implement a hearing conservation program, including audiometric testing, when worker noise exposure reaches or exceeds an 85 dBA 8-hour TWA action level.
Question 4: Which type of air-purifying respirator provides protection against both particulates and organic vapors simultaneously?
- Combination cartridge respirator (Correct answer)
- N95 filtering facepiece
- PAPR with HEPA filter only
- Supplied-air respirator
Correct answer: Combination cartridge respirator
Combination cartridges contain both a particulate filter and a sorbent bed for organic vapors, providing dual protection in environments with both hazard types.
Question 5: A company's industrial hygienist conducts exposure monitoring and finds results consistently below 50% of the PEL. Under OSHA guidelines, what is the minimum recommended reassessment interval?
- Every year or when process changes occur (Correct answer)
- Every 6 months
- Every 5 years
- No reassessment required if below 50% PEL
Correct answer: Every year or when process changes occur
Industry guidance recommends annual reassessment or whenever process, material, or control changes could affect exposure, even when results are well below the PEL.
Question 6: Which musculoskeletal disorder risk factor is most directly associated with performing tasks requiring sustained awkward wrist postures?
- Carpal tunnel syndrome (Correct answer)
- Rotator cuff tendinitis
- Trigger finger
- De Quervain's tenosynovitis
Correct answer: Carpal tunnel syndrome
Sustained flexion or extension of the wrist compresses the median nerve within the carpal tunnel, contributing to carpal tunnel syndrome.
Question 7: What does the term 'bioaccumulation' mean in occupational toxicology?
- The progressive accumulation of a substance in an organism over time because intake exceeds elimination (Correct answer)
- The breakdown of a toxicant into less harmful metabolites
- The absorption of a chemical through intact skin
- The sudden release of a stored chemical during illness
Correct answer: The progressive accumulation of a substance in an organism over time because intake exceeds elimination
Bioaccumulation occurs when a substance (e.g., organochlorine pesticides, heavy metals) is absorbed faster than it can be metabolized or excreted, increasing body burden over time.
HSE Occupational Health and Industrial Hygiene 5
Which ACGIH exposure limit category represents a concentration that should not be exceeded even instantaneously?