What is the primary limiting factor of a Self-Contained Breathing Apparatus (SCBA)?

The primary limiting factor of a Self-Contained Breathing Apparatus (SCBA) is air pressure, specifically the pressure measured in pounds per square inch (psi). SCBAs are designed to provide a supply of breathable air to firefighters and other emergency responders in environments that are immediately dangerous to life or health. The air supply is contained within a cylinder that operates at high pressure.

As firefighters use the SCBA, the pressure in the air cylinder decreases, which directly impacts the duration of air supply available. Once the pressure drops to a certain level, the SCBA becomes ineffective, and the wearer must exit the hazardous area to replenish their air supply. Understanding this limitation is crucial for effective time management and operational safety during firefighting and rescue operations.

While oxygen levels, temperature, and humidity can significantly affect breathing and environmental conditions, they do not directly limit the functionality and duration of the SCBA itself, which relies primarily on the available air pressure within the cylinder.