What is the upper bound of the safe oxygen level range?

What is the upper bound of the safe oxygen level range?

• A. 20%
• B. 22%
• C. 24%
• D. 26%

Answer: (B)

Balancing life support with fire safety is the key idea. In shipboard damage-control training, the breathable atmosphere in damaged spaces is kept within a safe window, typically from about 19.5% up to around 22%. Going higher increases the risk of ignition and rapid fire spread, so 22% is used as the upper limit in this context. Twenty percent is safe but not the ceiling, while 24% and 26% exceed the recommended ceiling and raise fire hazards. Therefore, the upper bound is about 22%.

Balancing life support with fire safety is the key idea. In shipboard damage-control training, the breathable atmosphere in damaged spaces is kept within a safe window, typically from about 19.5% up to around 22%. Going higher increases the risk of ignition and rapid fire spread, so 22% is used as the upper limit in this context.

Twenty percent is safe but not the ceiling, while 24% and 26% exceed the recommended ceiling and raise fire hazards. Therefore, the upper bound is about 22%.