What is the safe breathing level of oxygen in the atmosphere?

The safe breathing level of oxygen in the atmosphere is typically considered to be around 20.5%. This figure reflects the normal concentration of oxygen in the air we breathe, which is approximately 21% under standard atmospheric conditions. Levels at or above this concentration are deemed safe and adequate for human respiratory needs.

When providing context, oxygen levels lower than 19.5% can lead to oxygen deficiency and adversely affect physical and mental functioning. Conversely, levels significantly higher than the normal range can create potential hazards, as an increase in oxygen concentration may promote combustion or lead to other safety concerns. Therefore, while 21% oxygen is typical, 20.5% is recognized as a safe threshold to ensure proper oxygenation without elevated risks.

Maintaining this concentration is crucial in various environments, especially in occupational settings related to wastewater treatment, where monitoring air quality is essential for worker safety and health.