More significant is the observation that the laser through-put drops dramatically as a result of broad-band absorption by the halon mixture (halons 1301 and 1211). The decrease in transmitted laser through halon vapor is so severe that CO and CO2 concentrations could not be measured. Because halon 1301 is used onboard aircraft to suppress fires, it will be present after a fire is detected and the agent is released. The ability of the fire sensor system to continue monitoring the cargo compartments after the release of extinguishing agents could be compromised.