# Fighting wild fires with sub zero air

I understand this is probably too costly to be practical, but was intrigued how one might use the mechanism of fire combustion against itself. Fires produce their own retardants (water and carbon dioxide). If you could cool this with quantities of subzero air (e.g. from above) would the dense air attack the flow mechanism that feeds the fire (the oxygen intake at ground requires the upward escape of combustion products). If you had a mobile store of liquid nitrogen and a high-throughput turbine & heat exchanger, using the heat of vaporisation and heat capacity of liquid N2, could you 'hose' down a fire using subzero air?

• @JKB Nitrogen would put it out. So would any not-very-reactive gas. Fire needs three things: fuel, $O_2$ and ignition temp. You first have to cut off the oxygen to stop the combustion reaction and then cool the fuel below the ignition point so that it doesn't flare up again when the $O_2$ comes back. That's how $CO_2$ extinguishers work. – Oscar Bravo Feb 6 at 19:40