Oxygen is safe or normal under what conditions?

Oxygen is considered safe and normal at a concentration range of 19.5% to 23%. This range is established based on the understanding that atmospheric air contains approximately 21% oxygen. Levels below 19.5% indicate a deficiency that could lead to hypoxia, which is a state of insufficient oxygen for human breathing and can result in harmful effects. Conversely, levels above 23% increase the risk of fire and explosion, as high concentrations of oxygen can enhance combustion. Therefore, maintaining oxygen levels within this specified range ensures a safe environment for breathing as well as minimizing the risk of fire hazards. This understanding is essential for safety in environments such as industrial workplaces where the oxygen concentration can vary.