Question 27Safety & Environmental - Assistant Engineer

The correct answer is C) 20.8%. The oxygen level in fresh air is approximately 20.8%. This is the standard oxygen level that is considered safe and normal for human habitation. Before entering any sealed space, the oxygen level should be tested to ensure it is at this normal fresh air level, indicating the space is not oxygen-deficient or oxygen-enriched, which could pose safety hazards. The other answer choices are incorrect because 10.0% is dangerously low, 15.8% is below the normal range, and 25.8% would be considered oxygen-enriched, which also presents safety risks.