An atmosphere is considered oxygen-enriched if concentrations of oxygen are greater than:

An atmosphere is considered oxygen-enriched when the concentration of oxygen exceeds 21%, which is the normal atmospheric level. Specifically, a concentration above 23.5% is generally recognized as an oxygen-enriched environment. At this level, the potential for increased fire hazards and combustion risks significantly escalates, as oxygen supports and enhances combustion processes. Therefore, recognizing a threshold of 23.5% is crucial for safety in environments where flammable materials may be present. Understanding these thresholds is essential for Hazmat technicians, as it informs their decision-making and safety protocols while responding to incidents involving hazardous materials.