What is an indication of low air in an SCBA?

A decrease in the air pressure gauge reading is a clear indication of low air in a self-contained breathing apparatus (SCBA). The air pressure gauge is specifically designed to provide real-time feedback on the amount of air remaining in the cylinder. As the air is consumed, the pressure will decrease, reflecting the diminishing supply. This drop in pressure helps firefighters gauge when they need to exit a hazardous environment to refill or replace their SCBA.

While increased heart rate, noise from the air cylinder, and mask vibration can be physiological responses or indicators in other situations, they are not direct, measurable signs of low air in the SCBA system. Therefore, monitoring the air pressure gauge is the most reliable method for ensuring adequate air supply during operations.