What physical factor can increase stress while using an SCBA?

The weight of the cylinder is a significant physical factor that can increase stress while using a self-contained breathing apparatus (SCBA). When firefighters wear SCBAs, the added weight from the air cylinder can lead to fatigue and discomfort, especially during prolonged use or in physically demanding situations. This added weight requires more energy to carry, which can raise the heart rate and oxygen consumption, enhancing the physical stress placed on a firefighter's body.

While the weight of the harness and the volume of air contained in the SCBA also play roles in overall comfort and usability, the cylinder's weight is particularly impactful due to its direct contribution to the overall load the firefighter must manage. A heavy cylinder can significantly affect mobility and endurance, factors that are crucial in high-stress environments typical of firefighting situations.