Which type of SCBA allows for the recycling of exhaled air?

A closed-circuit SCBA is designed to recycle exhaled air, which means that the user breathes in oxygen from a reservoir and then, instead of releasing it into the environment, the exhaled air is processed, allowing the carbon dioxide to be filtered out and oxygen to be replenished. This system results in a longer duration of breathable air supply compared to an open-circuit SCBA, which expels exhaled air into the atmosphere and requires the user to carry a larger tank to ensure a sufficient air supply for the duration of use.

This recycling process is essential in environments where extending the operational time of the breathing apparatus is critical, such as in confined spaces or for longer-duration missions. Since a hybrid SCBA typically combines features of both open and closed-circuit systems, and emergency SCBAs are designed for short-term use in critical situations, they do not primarily focus on air recycling. Thus, the closed-circuit SCBA stands out as the only type that actively recycles exhaled air, making it the correct choice in this context.