Light and air unit

An air and light unit, also known as a breathing support unit or mobile air unit, is a specialized firefighting apparatus used by first responders to provide supplemental lighting and self-contained breathing apparatus cylinders and cylinder filling services at the scene of an emergency.^[1] During prolonged incidents surrounding an immediate danger to life or health environment, first responders working in unsafe environments wear a self-contained breathing apparatus. The depleted air cylinders within the breathing apparatus must be replaced and refilled throughout the incident.^[2] The air and light unit can refill the cylinders while in the field using an onboard air compressor and cascade system.^[1]

In the United States, Chapter 24 of National Fire Protection Association Regulation 1901 outlines specifications for any air system mounted on firefighting apparatus.^[3]