Which quantity is used to assess oxygen deficiency in confined spaces?

• A. Temperature
• B. Humidity
• C. Oxygen level
• D. Noise

Answer: (C)

In confined spaces, the essential risk is hypoxia from not having enough breathable oxygen, so the quantity you use to assess this hazard is the oxygen level in the air—the concentration of oxygen present. Measuring how much O2 is there tells you whether the environment is safe to enter or if it's deficient, which is critical because low oxygen can quickly lead to dizziness, confusion, loss of consciousness, or death. That’s why oxygen concentration is the standard indicator for oxygen deficiency.

Temperature, humidity, and noise relate to other hazards they can indicate or influence (like heat stress, comfort, or hearing risk), but they don’t tell you whether there’s enough oxygen for breathing. They don’t directly address the hypoxia hazard in confined spaces, which is why they aren’t used to assess oxygen deficiency.