A worker needs to enter a confined space that has been tested and shows 19% oxygen content. What action should be taken?
Correct Answer
C) Entry is prohibited until oxygen level is corrected
OSHA requires oxygen levels between 19.5% and 23.5% for safe confined space entry. At 19%, the space is oxygen-deficient and entry is prohibited until corrected.
Why This Is the Correct Answer
OSHA defines an oxygen-deficient atmosphere as one with less than 19.5% oxygen by volume. At 19%, the space is below this threshold and entry is prohibited until the condition is corrected (typically through forced-air ventilation). No respirator alone authorizes entry when the problem is atmospheric composition — the atmosphere itself must be brought into the safe range before entry. Note: the safe range is 19.5% to 23.5% oxygen.
Why the Other Options Are Wrong
Option A: Entry is permitted with emergency escape respirator
An emergency escape respirator (EEBA) is designed for emergency egress from a space already entered, not for planned entry into an oxygen-deficient environment. Using an escape respirator as entry equipment violates OSHA confined space rules.
Option B: Entry is permitted with supplied-air respirator
While a supplied-air respirator (SAR) can protect workers in some atmospheric hazard scenarios, OSHA's confined space standard requires that the atmosphere be brought into acceptable levels before entry when feasible. A SAR does not eliminate the underlying hazard and introduces additional risks (hose entanglement, equipment failure). Entry with SAR requires specific permit procedures, not standard practice.
Option D: Entry is permitted with standard PPE
Standard PPE (hard hat, gloves, safety glasses, boots) provides no respiratory protection whatsoever. Entering an oxygen-deficient atmosphere without respiratory protection at 19% O2 can cause rapid loss of consciousness — at 16% oxygen, workers lose consciousness without warning.
Memory Technique
The oxygen safe zone: 19.5% to 23.5%. Think of 19.5 as the 'floor' — below it, no entry, period. At 19%, you are below the floor. No equipment substitutes for correcting the atmospheric condition first.
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