What is the maximum allowable oxygen concentration by volume for an oxygen-enriched atmosphere?

In safety and health contexts, particularly concerning work environments, the standard maximum allowable oxygen concentration for an oxygen-enriched atmosphere is 23.5% by volume. This threshold is crucial because environments with oxygen levels higher than normal atmospheric levels (approximately 21% oxygen) can present significant fire hazards and risks of explosion.

When the oxygen concentration exceeds 23.5%, the risks associated with fire and combustion increase significantly, as higher oxygen concentration can facilitate the rapid ignition and spread of fires. Therefore, 23.5% is established as a limit to ensure safety and minimize hazards associated with oxygen-enriched conditions. Understanding this concentration level is vital for properly assessing and managing risks in workplaces where oxygen levels may be elevated due to various processes or activities.