Toxic products from fires.

Abstract

The role of toxic combustion products in causing fire deaths has received considerable public attention in recent years. This paper outlines critical aspects of the problem, including the identification of common combustion products, the toxicological effects of these products and the dependence of their formation on the combustion process itself. The significance of escape as the key to survival in a fire is particularly emphasized. This paper then focuses on the development of test methods for assessment of toxic hazards produced by burning materials, with the objective being to enable decisions to be made as to whether the use of one material, as opposed to another, would result in any significant difference in hazard to life safety in a fire. It is argued that smoke toxicity test methods which determine only lethal toxicological potency under “worst case” conditions do not satisfactorily address the critical issue of relative hazard, including time-to-escape and tenability limits resulting from the fire performance of materials under comparable conditions. Since threats to escape from a fire are largely time-dependent, toxic insults produced by burning materials should also be considered as rate processes. Assessment of time thresholds exhibited by burning materials under test conditions to effect performance impairment (incapacitation) of an animal model would appear to be more relevant than lethal toxicological potencies in estimating probability of successful escape from fires. A model is advanced in which intoxication rate thresholds for materials are obtained using a rodent exposure test method. Concentration-time curves, obtained from experimentally derived concentration-time-response surfaces, are the basis for estimating rate thresholds which are distinctively different for each material and which vary as a function of test conditions. It is this performance impairment response surface which is potentially a key to the modeling of toxic hazards of smoke in perspective with other hazards presented by fire. Only when overall hazards are appropriately assessed can smoke toxicity tests be meaningful as tools in choosing materials to reduce risk to life safety in fires.