Question 17Safety & Environmental - 1st Asst/Chief

The correct answer is C) 20.8%. The oxygen level in fresh air is approximately 20.8%. This is the standard level of oxygen that should be present in a space before it is entered. If the oxygen level in a sealed space is below 20.8%, it indicates that the oxygen has been depleted and the space may not be safe to enter without proper ventilation and testing. The other answer choices are incorrect because 10.0% is dangerously low, 15.8% is below the normal fresh air level, and 25.8% is abnormally high and could indicate the presence of enriched oxygen, which could also be hazardous.