What is the minimum concentration of oxygen required by law for safe breathing?

The minimum concentration of oxygen required for safe breathing, as specified by regulations, is 19.5%. This standard is established to ensure that individuals in environments such as mines can breathe safely without risking hypoxia or other health hazards associated with oxygen deficiency.

At levels below 19.5%, individuals may experience increasing risks, including impaired cognitive and physical performance, which can lead to dangerous situations, especially in the confined and potentially hazardous environments of a mine. Therefore, maintaining oxygen levels at or above this percentage is critical for occupational safety and health.

While other options may seem close, they do not meet the legal requirement set forth for safe breathing environments.