What does Closed-Circuit SCBA primarily reuse from exhaled air?

Closed-Circuit Self-Contained Breathing Apparatus (SCBA) primarily reuses carbon dioxide from exhaled air. In a closed-circuit system, the exhaled air is filtered to remove carbon dioxide and then undergoes rebreathing, allowing the wearer to utilize the oxygen that remains in the air. This is a critical feature of closed-circuit SCBAs, designed for extended operations in environments where oxygen supply may be limited, or environments that are hazardous.

The primary advantage of this system is the efficient use of the available resources, minimizing the need for frequent air supply replacements. While water vapor, oxygen, and nitrogen are part of the exhaled air, the key aspect of the closed-circuit system focuses on the management of carbon dioxide. By addressing carbon dioxide levels effectively, the SCBA helps maintain a breathable environment for the user over extended periods, making it a valuable tool for firefighters and other professionals who may encounter toxic atmospheres.