What is the minimum oxygen partial pressure (ATA) required to sustain human life?

The minimum oxygen partial pressure required to sustain human life is 0.16 ATA. This level corresponds to approximately 16% oxygen in the atmosphere, which is the threshold below which hypoxia, or insufficient oxygen, becomes life-threatening. At this partial pressure, humans can survive, but it represents a critical limit for safe functioning. Environments with oxygen partial pressures below this level can result in impaired cognitive and physical abilities, and prolonged exposure can lead to unconsciousness or death.

Understanding this threshold is crucial in diving and rescue operations, where maintaining an appropriate oxygen mix is essential for the safety of individuals at depth. While 0.2 ATA and higher levels provide comfortable living conditions and active functioning, levels below 0.16 ATA put individuals at significant risk, highlighting the importance of monitoring environmental gas compositions in rescue scenarios.