CHST Confined Space Entry and Rescue 2 — Questions and Answers
Question 1: Under OSHA definitions, 'engulfment' in a confined space refers to:
- An entrant becoming disoriented due to toxic atmospheric conditions
- The surrounding and effective capture of a person by finely divided solids or liquid (Correct answer)
- The collapse of a confined space wall or ceiling onto an entrant
- A rapid drop in oxygen levels that incapacitates an entrant
Correct answer: The surrounding and effective capture of a person by finely divided solids or liquid
OSHA defines engulfment as the surrounding and effective capture of a person by a liquid or finely divided flowable solid, which can cause asphyxiation, strangulation, constriction, or crushing.
Question 2: When a non-permit confined space must be reclassified as permit-required, which condition most commonly triggers this change?
- The space has not been inspected for more than 6 months
- Work activities inside the space create additional hazards such as welding fumes or oxygen displacement (Correct answer)
- More than two workers are required to enter simultaneously
- The space is accessed after normal working hours
Correct answer: Work activities inside the space create additional hazards such as welding fumes or oxygen displacement
When work performed inside a non-permit confined space introduces new hazards—such as welding that generates toxic fumes or displaces oxygen—the space must be reclassified as permit-required.
Question 3: Which type of forced ventilation is most effective for purging a confined space of vapors heavier than air?
- Natural ventilation through the top opening only
- Forced air supply directed through the top of the space
- Forced air supply directed near the bottom of the space (Correct answer)
- Exhaust ventilation from the top of the space only
Correct answer: Forced air supply directed near the bottom of the space
Vapors heavier than air settle at the lowest points of confined spaces; directing forced air supply near the bottom effectively displaces and purges these vapors upward and out.
Question 4: What information is NOT required on an OSHA-compliant confined space entry permit?
- Acceptable entry conditions and atmospheric test results
- The hazards of the permit space and measures to eliminate or control them
- The employer's general liability insurance policy number (Correct answer)
- Authorized entrants and the entry supervisor
Correct answer: The employer's general liability insurance policy number
Entry permits must contain safety and operational information including space identification, hazards, atmospheric test results, authorized personnel, and emergency procedures—not financial or insurance data.
Question 5: A hydrogen sulfide (H₂S) concentration of 300 ppm inside a confined space represents what condition?
- An acceptable level that requires increased monitoring
- A level requiring use of air-purifying respirators
- An IDLH (Immediately Dangerous to Life or Health) condition (Correct answer)
- A level that requires ventilation but permits continued entry
Correct answer: An IDLH (Immediately Dangerous to Life or Health) condition
NIOSH establishes the IDLH for hydrogen sulfide at 100 ppm; a concentration of 300 ppm far exceeds this threshold and represents an immediately life-threatening condition requiring immediate evacuation.
Question 6: In confined space operations involving multiple employers on a construction site, what does OSHA require?
- Only the controlling contractor's safety program applies to all workers
- Employers must coordinate entry operations and share information about space hazards with each other (Correct answer)
- Each employer must establish a completely independent entry program with no coordination
- The employer with the most workers assumes full safety responsibility
Correct answer: Employers must coordinate entry operations and share information about space hazards with each other
Under 29 CFR 1926 Subpart AA, when multiple employers are involved, they must coordinate entry operations and exchange relevant information about space hazards and entry procedures to protect all workers.
Question 7: What is the purpose of 'isolation' as a hazard control step in confined space entry?
- To prevent unauthorized workers from approaching the permit space perimeter
- To physically disconnect energy sources and block introduction of hazardous materials into the space (Correct answer)
- To establish visual barriers around the confined space for emergency access
- To separate the confined space from adjacent work areas using barricade tape
Correct answer: To physically disconnect energy sources and block introduction of hazardous materials into the space
Isolation involves locking out/tagging out energy sources, blanking or blinding pipe connections, and otherwise physically preventing hazardous energy or substances from entering or affecting the space.
CHST Confined Space Entry and Rescue 2
Under OSHA definitions, 'engulfment' in a confined space refers to: