CHST Confined Space Entry and Rescue 1 — Questions and Answers
Question 1: Which OSHA standard specifically governs confined spaces in construction?
- 29 CFR 1910.146
- 29 CFR 1926 Subpart AA (1926.1200-1213) (Correct answer)
- 29 CFR 1926.502
- 29 CFR 1926.650
Correct answer: 29 CFR 1926 Subpart AA (1926.1200-1213)
OSHA's 29 CFR 1926 Subpart AA (1926.1200-1213) specifically addresses confined spaces in construction, establishing requirements for permit spaces, entry procedures, training, and rescue.
Question 2: What oxygen concentration range is considered acceptable for entry into a confined space?
- 14.5% to 23.5%
- 19.5% to 23.5% (Correct answer)
- 16% to 21%
- 18% to 25%
Correct answer: 19.5% to 23.5%
OSHA defines the acceptable oxygen range as 19.5% to 23.5%; below 19.5% is oxygen-deficient and above 23.5% is oxygen-enriched, both requiring special precautions.
Question 3: Before an authorized entrant enters a permit-required confined space, which atmospheric tests must be conducted?
- Oxygen content only
- Flammable gases only
- Oxygen content, flammable gases, and toxic contaminants (Correct answer)
- Carbon monoxide only
Correct answer: Oxygen content, flammable gases, and toxic contaminants
OSHA requires testing for oxygen content, flammable gases/vapors, and potential toxic air contaminants before entry to ensure all atmospheric hazards are identified.
Question 4: At what percentage of the Lower Explosive Limit (LEL) must workers immediately evacuate a permit-required confined space?
- 5% LEL
- 10% LEL (Correct answer)
- 15% LEL
- 25% LEL
Correct answer: 10% LEL
OSHA requires evacuation when flammable gas concentrations reach 10% of the LEL, providing a safety margin well below the actual explosive threshold.
Question 5: Who has the authority and responsibility to cancel a confined space entry permit if conditions become unsafe?
- The authorized entrant
- The entry supervisor (Correct answer)
- The attendant
- The company safety director
Correct answer: The entry supervisor
The entry supervisor has the authority and responsibility to cancel the entry permit if conditions change or a hazard develops that makes the space unsafe for entry.
Question 6: What is the primary role of the confined space attendant during entry operations?
- To assist entrants with work tasks from just inside the entrance
- To remain outside, monitor entrants and conditions, and initiate rescue if needed (Correct answer)
- To continuously test the atmosphere inside the confined space
- To document entry procedures for compliance records
Correct answer: To remain outside, monitor entrants and conditions, and initiate rescue if needed
The attendant must remain outside the permit space, continuously track entrants, maintain communication, monitor for hazards, and initiate emergency rescue procedures without entering the space.
Question 7: A confined space is classified as 'permit-required' when it meets the definition of a confined space AND:
- Has a volume of less than 300 cubic feet
- Contains or has the potential to contain a serious safety or health hazard (Correct answer)
- Requires more than one worker to perform tasks inside
- Is located below grade or underground
Correct answer: Contains or has the potential to contain a serious safety or health hazard
A confined space becomes permit-required when it contains or has the potential to contain a serious atmospheric, engulfment, entrapment, or other recognized serious safety or health hazard.
CHST Confined Space Entry and Rescue 1
Which OSHA standard specifically governs confined spaces in construction?