What is the minimum oxygen level required for a safe atmosphere?

A minimum oxygen level of 19.5% is required for a safe atmosphere because this percentage is recognized as the threshold below which the atmosphere can become hazardous to health. At this level, individuals may start to experience symptoms of oxygen deficiency, which can lead to impaired cognitive and physical functions. In work environments, particularly those where employees might be exposed to confined spaces or specific tasks that could deplete oxygen, knowing this threshold is crucial for safety regulations and procedures.

The 21% mark represents the standard concentration of oxygen in the atmosphere, but safety regulations set the minimum safe limit at 19.5% to ensure that individuals can operate without adverse effects. Levels of oxygen below this can be considered unsafe and may pose serious risks.