To ensure safe human respiration, continuous work inside an enclosed space requires a constant oxygen level of:
Direct Answer
Option D: 21% oxygen concentration
Standard atmospheric oxygen levels are approximately 21%. When working in enclosed spaces, any deviation from this level (e.g., lower due to consumption/rusting, or higher/lower due to gases) poses a health risk; 21% is the requirement for safe breathing.
All Options
Detailed Explanation & Context
Standard atmospheric oxygen levels are approximately 21%. When working in enclosed spaces, any deviation from this level (e.g., lower due to consumption/rusting, or higher/lower due to gases) poses a health risk; 21% is the requirement for safe breathing.
Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • Personal Safety & Social Responsibilities (PSSR).
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