In terms of operation, what is the main role of SCBA (self-contained breathing apparatus)?

The primary function of a self-contained breathing apparatus (SCBA) is to provide firefighters with a safe supply of breathable air while operating in environments that are immediately dangerous to life and health (IDLH), such as areas filled with smoke, toxic gases, or low oxygen levels. The SCBA has a tank that contains compressed air, allowing firefighters to work in hazardous conditions without risking suffocation or inhalation of harmful substances.

While the other options describe features or benefits that may be associated with the respiratory protection system, they do not encapsulate the main operational role of an SCBA. For instance, SCBAs do not directly protect from heat and flames; rather, they protect the respiratory system, allowing firefighters to focus on their tasks in dangerous environments. Similarly, SCBAs do not aid in transportation or climbing; they are designed specifically for respiratory safety. Lastly, although SCBAs may include audible alarms to signal low air levels, this is a secondary feature and not the primary role of the device.