An atmosphere is defined as oxygen deficient if it contains less than what percent oxygen by volume?

An atmosphere is defined as oxygen deficient when the concentration of oxygen by volume falls below 19.5%. This threshold is significant in occupational health and safety standards because oxygen levels below this percentage can lead to physiological effects such as impaired cognitive function, decreased coordination, and potentially life-threatening situations.

In environments where oxygen levels are critically low, workers may be at risk of suffocation or other serious health issues. Therefore, knowing this threshold is crucial for ensuring safety protocols are followed in wastewater collection and other industries dealing with confined spaces or potential oxygen deficiency situations. Maintaining oxygen levels above this minimum is essential to protect workers in such environments, which is why 19.5% is widely recognized as the cutoff for defining an oxygen-deficient atmosphere.