What percentage of oxygen in the air is categorized as oxygen-rich and may pose a fire risk?

Oxygen-rich environments are typically defined by the concentration of oxygen in the air being significantly higher than the normal atmospheric level, which is approximately 21% oxygen. When the percentage of oxygen in the air exceeds 23.5%, it is considered a fire risk because increased oxygen can enhance combustion processes. At this concentration, materials that normally do not burn easily may ignite more readily, and existing fires can become more intense.

Understanding the implications of different oxygen levels is crucial for firefighters and those operating in hazardous materials environments, as it directly relates to safety practices and firefighting strategies. Recognizing that oxygen concentrations above 23.5% can lead to an increased risk of fires helps responders take necessary precautions when entering such environments.