What is the main function of the PBE device?

The primary function of the PBE (Protective Breathing Equipment) device is to protect the user's eyes and lungs from smoke and toxic fumes. This equipment is critical in emergency situations, particularly during in-flight emergencies, where smoke or harmful gases may be present due to an onboard fire or other hazardous situations.

PBE devices are designed to create a safe breathing environment by supplying filtered air and shielding the user's face with a protective hood. This protection is essential for crew members and passengers to safely navigate through smoke-filled areas and evacuate an aircraft or resolve an emergency.

While the other options mention important functions related to cabin safety and emergency response, they do not accurately reflect the specific role of the PBE. Enhancing cabin pressure pertains more to pressure control systems, supplemental oxygen is related to breathing augmentation rather than protection from fumes, and monitoring cabin temperature is conducted by separate systems designed for climate control and safety monitoring within the aircraft. The PBE's unique focus on personal protection from immediate harmful elements makes it vital during emergencies, highlighting why it is the correct choice in this context.