According to OSHA's hazardous material definition, which atmospheric condition is considered safe?

In the context of OSHA's definition of hazardous materials, the standard atmosphere for safe working conditions is primarily the percentage of oxygen in the air. Normal atmospheric air contains approximately 20.8% oxygen. This level allows for proper respiratory function and minimizes the risk of hypoxia (oxygen deficiency) in workers.

When the oxygen concentration drops below 19.5%, environments can begin to pose health risks, as lower levels of oxygen can impair physical and mental performance and can be life-threatening. Therefore, the percentage of 20.8% is recognized as safe and represents typical atmospheric conditions.

Although other oxygen levels provided in the options may seem close to the optimal level, they either present potential hazards or do not reflect the preferred atmospheric condition for safety in workplaces involving hazardous materials.