The Oxygen Safe Zone is defined as which percentage range?

The Oxygen Safe Zone is defined as which percentage range?

• A. 16% to 20%
• B. 19.5% to 23.5%
• C. 25% to 30%
• D. 15% to 18%

Answer: (B)

The Oxygen Safe Zone is the range where the oxygen level is high enough for normal breathing but not so high that it creates a fire hazard. That safe range is about 19.5% to 23.5% O2. Normal outdoor air is around 20.9% O2, so this window covers typical conditions while guarding against hypoxia (below 19.5%) and oxygen-enriched environments (above 23.5%), which can increase fire risks. So, conditions within 19.5% to 23.5% are considered safe for routine work.

The Oxygen Safe Zone is the range where the oxygen level is high enough for normal breathing but not so high that it creates a fire hazard. That safe range is about 19.5% to 23.5% O2. Normal outdoor air is around 20.9% O2, so this window covers typical conditions while guarding against hypoxia (below 19.5%) and oxygen-enriched environments (above 23.5%), which can increase fire risks. So, conditions within 19.5% to 23.5% are considered safe for routine work.