For purposes of code compliance, an oxygen-enriched atmosphere is defined as an atmosphere where the total concentration of oxygen exceeds what percentage by volume?

An oxygen-enriched atmosphere is specifically defined as an environment where the concentration of oxygen exceeds 23.5% by volume. This threshold is significant because higher oxygen levels can increase the risk of fire and combustion. In typical atmospheric air, oxygen makes up about 21% by volume. When it exceeds 23.5%, it becomes classified as an oxygen-enriched atmosphere, signaling heightened caution and the need for adherence to safety protocols due to the potential hazards associated with increased oxygen levels. Establishing this standard is crucial for ensuring safe practices in environments where oxygen is used or stored, particularly in medical settings. This definition is consistent with guidelines from organizations such as the National Fire Protection Association (NFPA) and the Occupational Safety and Health Administration (OSHA).