What type of respiratory protection is required when the atmospheric oxygen level in a confined space is 16%?
Correct Answer
C) Supplied-air respirator or SCBA
When oxygen levels fall below 19.5%, the atmosphere is considered oxygen-deficient and requires supplied-air respirators or self-contained breathing apparatus (SCBA). Air-purifying respirators cannot add oxygen to deficient atmospheres.
Why This Is the Correct Answer
When atmospheric oxygen levels drop below 19.5%, the environment is classified as oxygen-deficient per OSHA standards. At 16% oxygen, workers face serious health risks including impaired judgment, increased heart rate, and potential unconsciousness. Only supplied-air respirators or self-contained breathing apparatus (SCBA) can provide a reliable source of breathable air independent of the surrounding atmosphere. Air-purifying devices cannot increase oxygen concentration in deficient environments.
Why the Other Options Are Wrong
Option A: Air-purifying respirator
Air-purifying respirators only filter contaminants from ambient air but cannot add oxygen to oxygen-deficient atmospheres. They rely on the surrounding air having adequate oxygen levels (19.5% or higher) to function safely.
Option B: Powered air-purifying respirator
Powered air-purifying respirators, while providing forced air circulation, still draw from the ambient atmosphere and cannot supplement oxygen levels. They are ineffective in oxygen-deficient environments below 19.5%.
Option D: No respiratory protection needed
Respiratory protection is absolutely required when oxygen levels fall below 19.5%. At 16% oxygen, workers face immediate danger to life and health (IDLH) conditions requiring the highest level of respiratory protection.
Memory Technique
Remember '19.5 to Stay Alive' - below this oxygen level, you need supplied air to survive, not filtered air.
Reference Hint
OSHA 29 CFR 1926.95 (Personal Protective Equipment) and 29 CFR 1926.1200 series (Confined Space standards)
More Project Mgmt Questions
What is the minimum R-value required for wall insulation in Florida Climate Zone 2?
A subcontractor brings a new chemical product to your jobsite. Under the Globally Harmonized System (GHS), what information must be immediately available to workers?
A construction site has a trench that is 8 feet deep in Type B soil. What is the maximum allowable slope ratio for the trench walls without protective systems?
A detail drawing shows a scale of 3/4" = 1'-0". If a dimension measures 2.25 inches on the drawing, what is the actual dimension?
What is the maximum recommended spacing between drywall screws when attaching to wood studs?
People Also Study
Business & Financial Management
120 questions · 70% to pass
Contract Administration
60 questions · 70% to pass
Previous Question
In steel framing, what type of weld is most commonly used for connecting steel beams to columns?
Next Question
You receive shop drawings for custom millwork that show different wood species than specified. The substitution offers better durability but costs 15% more. What should you do?