AQS Health & Safety Protocols 2 — Questions and Answers
Question 1: Under OSHA's Permissible Exposure Limit (PEL) for respirable crystalline silica, what is the 8-hour TWA limit for general industry?
- 100 μg/m³
- 50 μg/m³ (Correct answer)
- 250 μg/m³
- 25 μg/m³
Correct answer: 50 μg/m³
OSHA's PEL for respirable crystalline silica in general industry is 50 μg/m³ as an 8-hour TWA.
Question 2: Which respiratory protection program element is required by OSHA 29 CFR 1910.134 before an employee uses a tight-fitting respirator?
- Annual industrial hygiene survey
- Medical evaluation by a physician or PLHCP (Correct answer)
- Completion of a Hazard Communication training
- Issuance of a fit-test waiver
Correct answer: Medical evaluation by a physician or PLHCP
OSHA 1910.134 requires a medical evaluation by a licensed physician or other licensed healthcare professional (PLHCP) prior to fit testing or respirator use.
Question 3: A community living near a chemical plant reports frequent headaches and eye irritation. Which acute health endpoint should the air quality specialist prioritize investigating first?
- Mesothelioma incidence
- Irritant gas exposures at ground-level (Correct answer)
- Long-term carcinogen bioaccumulation
- Noise-induced hearing loss
Correct answer: Irritant gas exposures at ground-level
Acute mucous-membrane irritation symptoms (headaches, eye irritation) most directly implicate short-term exposures to irritant gases at breathing level.
Question 4: Which document establishes the hierarchy of controls for occupational air contaminants, from most to least preferred?
- NIOSH Pocket Guide to Chemical Hazards
- OSHA 29 CFR 1910.1000 Table Z-1
- ANSI/AIHA Z10 Occupational Health and Safety Management System standard (Correct answer)
- EPA National Ambient Air Quality Standards
Correct answer: ANSI/AIHA Z10 Occupational Health and Safety Management System standard
ANSI/AIHA Z10 formally establishes the hierarchy of controls (elimination → substitution → engineering → administrative → PPE) for occupational hazards.
Question 5: A worker is potentially exposed to hydrogen sulfide (H₂S) at 20 ppm for a 10-hour shift. What action is most appropriate based on NIOSH guidance?
- No action needed; 20 ppm is below the IDLH
- Provide supplied-air respirator; NIOSH REL ceiling is 10 ppm (Correct answer)
- Issue a half-face particulate respirator rated P100
- Reduce shift length to 6 hours with no other controls
Correct answer: Provide supplied-air respirator; NIOSH REL ceiling is 10 ppm
NIOSH sets a ceiling REL of 10 ppm for H₂S; exposures at 20 ppm exceed this limit and require engineering controls and appropriate respiratory protection.
Question 6: Which type of ventilation system is specifically designed to capture contaminants at the point of generation before they enter the worker's breathing zone?
- General dilution ventilation
- Local exhaust ventilation (LEV) (Correct answer)
- Make-up air system
- Recirculating HVAC
Correct answer: Local exhaust ventilation (LEV)
Local exhaust ventilation captures contaminants at the source, preventing them from dispersing into the general work environment.
Question 7: When conducting confined space entry with potential oxygen deficiency, what minimum oxygen concentration must be maintained for safe work per OSHA standards?
- 16.0%
- 19.5% (Correct answer)
- 21.0%
- 23.5%
Correct answer: 19.5%
OSHA requires a minimum atmospheric oxygen concentration of 19.5% for safe occupancy in a confined space.
AQS Health & Safety Protocols 2
Under OSHA's Permissible Exposure Limit (PEL) for respirable crystalline silica, what is the 8-hour TWA limit for general industry?