What type of air does a Closed-Circuit SCBA use?

A Closed-Circuit Self-Contained Breathing Apparatus (SCBA) uses compressed oxygen to provide the user with a breathable atmosphere in environments that are immediately dangerous to life and health (IDLH). Unlike open-circuit SCBAs, which release exhaled air into the environment, closed-circuit SCBAs recycle the exhaled air by removing carbon dioxide and replenishing the oxygen, ensuring a continuous supply of breathable air.

This system allows firefighters to efficiently use the available air supply, extending their operational time in hazardous conditions. The focus on compressed oxygen emphasizes the need for high-quality air without contaminants that could jeopardize the user's safety and effectiveness in emergency situations.

While compressed air, ambient air, and filtered air may be used in other breathing apparatus systems, they do not meet the specific operational design and safety requirements of closed-circuit systems.