At what oxygen concentration level does disorientation and impaired muscle control begin to occur?

Disorientation and impaired muscle control begin to occur at an oxygen concentration level of 17%. At this concentration, individuals may start to experience noticeable effects due to insufficient oxygen supply for normal brain and muscle function. As the oxygen levels drop below the normal atmospheric concentration of around 21%, the body begins to react adversely, and at 17%, these reactions are particularly pronounced, leading to symptoms like disorientation and a decrease in physical coordination. This understanding is crucial, particularly in emergency response and firefighting situations, where maintaining physical and mental clarity is essential for safety and effective performance.