What is the minimum air pressure required upon initial entry?

The minimum air pressure required upon initial entry is 5500 psi because this pressure ensures that firefighters are provided with adequate breathing air for their operations in hazardous environments. The high-pressure requirement accounts for the possibility of air consumption during exertion, maintaining a sufficient reserve for safety and emergency scenarios. This level of pressure is designed to enhance the safety protocols that are critical in firefighting, giving responders the necessary time to carry out their duties effectively while having enough air supply to retreat if needed.

The other levels of pressure do not meet the safety standards required for optimal operation under potentially dangerous conditions. Lower pressures could lead to inadequate air supply for the duration of the operation, which is especially crucial considering the physical demands and unpredictability of firefighting situations.