:Light and air unit
{{Short description|Specialized firefighting apparatus}}
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.{{cite web|title=Light Air 1|url=http://www.sbcfire.com/wp-content/uploads/2012/05/Light-Air1.pdf|website=Santa Barbara County Fire|access-date=25 March 2015}} 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.{{cite web|title=Apparatus|url=http://lafd.org/about/apparatus|website=Los Angeles Fire Department|access-date=25 March 2015|date=2014-08-05}} The air and light unit can refill the cylinders while in the field using an onboard air compressor and cascade system. It also carries a supply of spare air cylinders. Air and light units are highly customizable and can vary significantly between departments.{{cite web|title=Air & Light Unit |url=https://www.e-one.com/products/rescues-and-command-center/air-light-unit |publisher=E-One |access-date=7 April 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150227085049/http://www.e-one.com/products/rescues-and-command-center/air-light-unit |archive-date=27 February 2015 }} Units are also equipped with diesel generators, which supply electricity to power portable lights and overall scene illumination equipment.{{cite journal|last1=Peters|first1=William|title=Apparatus Purchasing: Back to Basics|journal=Fire Engineering Magazine|date=9 January 2012|volume=165|issue=6|url=http://www.fireengineering.com/articles/print/volume-165/issue-6/apparatus-supplement/apparatus-purchasing-back-to-basics.html|access-date=7 April 2015}} This is usually done via a roof-mounted telescoping light bank. Units may typically supply electrical power in an emergency to a shelter, base camp, or medical facility.{{Citation needed|date=April 2024}}
In the United States, Chapter 24 of National Fire Protection Association Regulation 1901 outlines specifications for any air system mounted on firefighting apparatus.{{citation|title=Standard for Automated Fire Apparatus (NFPA 1901)|chapter=24 - Air Systems|edition=2009|pages=92–100|publisher=National Fire Protection Association}}
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| File:Santa Monica Fire Department Air & Light apparatus.jpg
| alt1=A Santa Monica Fire Department Air and Light unit
| A Santa Monica Fire Department Air and Light unit
| File:Santa Monica Fire Department Air & Light apparatus rear.jpg
| alt2=The SCBA bottle filler on the back of SMFD Air and Light 1
| The SCBA bottle filler on the back of SMFD Air and Light 1
| File:Toronto Fire Services Air Light.jpg
| alt3=A Toronto Fire Services Air and Light unit
| A Toronto Fire Services Air and Light unit
}}