At what oxygen level by volume is oxygen deficiency classified?

Oxygen deficiency is classified when the oxygen level in the air falls below 19.5% by volume. At this threshold, the risk of hypoxia increases, which can lead to symptoms such as dizziness, shortness of breath, and impaired judgment. Below this level, individuals may struggle to function normally, and there’s a heightened risk for serious health issues. Therefore, the specific measurement of 19.5% is significant because it highlights the point at which there is not enough oxygen for safe and efficient biological functioning.

Higher levels, such as 20% or 19.0%, are within the normal range for the atmosphere and do not indicate a deficiency, while 18.5% and lower are increasingly hazardous situations. Understanding this classification is crucial for safety regulations and workplace protocols, especially in environments where oxygen levels can fluctuate.