Inergen is a mixture of nitrogen, argon and carbon dioxide gases and has been specially developed to provide fire protection as a Halon1301 replacement.

Inergen extinguishes fire by reducing the oxygen level in a room to below 15%, the point at which most combustibles will no longer burn. Simultaneously the carbon dioxide in Inergen (IG-541) stimulates the uptake of oxygen by the human body, so protecting anyone who might be trapped in the fire area from the effects of the lowered oxygen levels.