The acute lethality of thermal decomposition products of various polymeric materials was investigated using bioassay procedures and a small scale combustion apparatus. The concentrations of pertinent fire gases individually and in various combinations and the amount of combusted material needed to cause 50% lethality (LC 50 ) during a planned 30 minute exposure and 10 minute recovery period were determined along with the lethal blood cyanide and carboxyhemoglobin (COHb) concentrations. Also, the results of controlled pure gas experiments with CO, HCN, CO 2 , or low O 2 singly or in combination are used in an attempt to explain their role during intoxication by smoke from a variety of polymeric materials, particularly those containing nitrogen and yielding HCN during thermal decomposition. These data gathered in controlled and combustion experiments using mice are compared to toxicological findings in human fire fatalities in an attempt to establish a threshold value for fatal cyanide concentrations in the blood of fire fatalities.

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