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.
The depleted air cylinders within the breathing apparatus must be replaced and refilled throughout the incident.
Air and light units are highly customizable and can vary significantly between departments.
Units may typically supply electrical power in an emergency to a shelter, base camp, or medical facility.
[citation needed] In the United States, Chapter 24 of National Fire Protection Association Regulation 1901 outlines specifications for any air system mounted on firefighting apparatus.