Your crew is entering a below-grade utility vault for cable installation. The atmospheric testing reveals 19.2% oxygen content. What action should be taken?
Correct Answer
C) Provide continuous forced air ventilation
Oxygen levels between 19.5% and 23.5% are considered safe. At 19.2%, the space is oxygen-deficient and requires continuous forced air ventilation to maintain safe atmospheric conditions before and during entry.
Why This Is the Correct Answer
At 19.2% oxygen, the confined space is oxygen-deficient (below the safe minimum of 19.5%). OSHA requires continuous forced air ventilation to increase and maintain oxygen levels during entry. This is the appropriate first response before considering more restrictive measures like supplied-air respirators or prohibiting entry entirely.
Why the Other Options Are Wrong
Option A: Prohibit entry until oxygen levels are corrected
Supplied-air respirators are not the first required response at 19.2% oxygen. While they may be needed if ventilation fails to restore safe levels, OSHA standards require attempting ventilation first. This oxygen level is deficient but not immediately life-threatening, making ventilation the appropriate initial corrective action.
Option B: Proceed with normal entry procedures
Normal entry procedures cannot be used when oxygen levels are below 19.5%. The 19.2% reading indicates oxygen deficiency, making the space immediately dangerous. Entry without corrective measures would violate OSHA confined space standards and endanger worker safety.
Option D: Require supplied-air respirators for entry
Complete entry prohibition is unnecessarily restrictive at 19.2% oxygen. This level, while deficient, can typically be corrected with proper ventilation. OSHA allows entry with appropriate controls rather than absolute prohibition when atmospheric hazards can be effectively managed through engineering controls like forced air ventilation.
Memory Technique
Remember '19.5 to Stay Alive' - below 19.5% oxygen requires ventilation to survive confined space entry.
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