What limits the application of self-contained breathing apparatus (SCBA) in confined space operations?

The choice indicating that both cylinder size and the duration of air supply limit the application of self-contained breathing apparatus (SCBA) in confined space operations is accurate. SCBA units work by supplying breathable air from a stored source, which is contained in a high-pressure cylinder. The size of this cylinder, particularly in terms of volume and pressure, determines how much air is available for the user.

In confined space scenarios, operations may require extended periods in situations where there are hazardous atmospheres. The duration of air supply becomes a critical consideration, as it dictates how long a user can safely operate within the confined space before needing to exit to avoid running out of breathable air. If the air supply is limited, it restricts the time that responders can spend working in the confined space, potentially impacting their effectiveness and safety.

In summary, the limitations imposed by cylinder size and the duration of air supply are significant factors that affect the practicality and effectiveness of SCBA in confined space operations, aligning with the selected answer.