Halon is a “Clean Agent.” The National Fire Protection Association defines, a “Clean Agent” as “an electrically non-conducting, volatile, or gaseous fire extinguishant that does not leave a residue upon evaporation.”
Halon is a liquefied, compressed gas that stops the spread of fire by chemically disrupting combustion. Halon 1211 (a liquid streaming agent) and Halon 1301 (a gaseous flooding agent) leave no residue and are remarkably safe for human exposure. Halon is rated for class “B” (flammable liquids) and “C” (electrical fires), but it is also effective on class “A” (common combustibles) fires. Halon 1211 and Halon 1301 are low-toxicity, chemically stable compounds that, as long as they remain contained in cylinders, are easily recyclable.