What is the cutoff percentage for an atmosphere to be classified as oxygen deficient?

What is the cutoff percentage for an atmosphere to be classified as oxygen deficient?

• A. 20%
• B. 21%
• C. 19.5%
• D. 18%

Answer: (C)

An atmosphere is classified as oxygen deficient when the oxygen concentration drops below 19.5%. This threshold is significant because normal atmospheric air contains approximately 21% oxygen. Levels below 19.5% can impair physical and mental performance and pose serious health risks to individuals exposed to such environments for extended periods. This classification is critical, especially in fire service operations, as familiarity with oxygen levels directly relates to personnel safety during emergency response situations. Understanding these limits helps firefighters assess the safety of their operating environments, ensuring that proper precautions are taken to prevent asphyxiation or other hazardous conditions.

An atmosphere is classified as oxygen deficient when the oxygen concentration drops below 19.5%. This threshold is significant because normal atmospheric air contains approximately 21% oxygen. Levels below 19.5% can impair physical and mental performance and pose serious health risks to individuals exposed to such environments for extended periods. This classification is critical, especially in fire service operations, as familiarity with oxygen levels directly relates to personnel safety during emergency response situations. Understanding these limits helps firefighters assess the safety of their operating environments, ensuring that proper precautions are taken to prevent asphyxiation or other hazardous conditions.