What percentage of oxygen concentration is considered oxygen deficient according to OSHA?

The correct choice indicates that a concentration of oxygen at 19.5% or lower is considered oxygen-deficient according to the Occupational Safety and Health Administration (OSHA). This threshold is critical for ensuring worker safety in environments where oxygen levels can be altered due to various factors, such as chemical reactions or confined spaces.

Normal atmospheric air contains approximately 21% oxygen. When oxygen levels drop to 19.5%, individuals may start to experience symptoms of hypoxia, which can include difficulty breathing, diminished cognitive function, and increased heart rate. OSHA has established this percentage as the minimum level required to maintain health and safety in the workplace. Therefore, when working in environments where oxygen may be displaced or consumed, it is essential for safety protocols to monitor and manage oxygen concentrations, keeping them above this critical level to avoid dangerous situations.

Other percentages listed in the options either fall within the normal range of atmospheric oxygen or are not recognized as thresholds for oxygen deficiency within relevant safety regulations and guidelines. This makes the 19.5% figure a key standard for safety in occupational settings.