Smoke toxicity measurement

Gann, R., Babrauskas, V., Peacock, R., and Hall, J., Fire conditions for smoke toxicity measurement. Fire and Materials 1994, 18, 193-199. 

Consequently, smoke toxicity measurements are often of minimal consequence to fire-hazard assessment. 

Hirschler, M.M., Smoke toxicity measurements made so that the results can be used for improved fire safety, J. Fire Sci. 9, 330-47 (1991). 

As these strategies are brought to fruition, there remains one related issue the determination of a smoke s potential harm per mass of material burned, i.e., the toxic potency of smoke. Accurate measurement of this key characteristic of fire smoke permits a more quantitative determination of the fire s toxic hazard which includes other factors as discussed below. Toxic potency assessment also tells us whether a small fire will produce smoke so toxic that only a small amount will kill. The presence of such "supertoxicants" has been a major topic of discussion within the fire community. 

Knowing the impact of smoke toxic potency on escape from a fire is of sufficient importance that it has been the subject of research for over twenty years. As a result, we now have a realistic picture of proper contexts for the use of toxic potency data and a series of first-generation tools for measuring it. We also have a vision of the key technical issues to be resolved developing a proper small-scale fire simulator, relating rodent results to people, and validating the small-scale data. 

During the 1970 s and early 1980 s a large number of test methods were developed to measure the toxic potency of the smoke produced from burning materials. The ones most widely used are in refs. 29-32. These tests differ in several respects the conditions under which the material is burnt, the characteristics of the air flow (i.e. static or dynamic), the type of method used to evaluate smoke toxicity (i.e. analytical or bioassay), the animal model used for bioassay tests, and the end point determined. As a consequence of all these differences the tests result in a tremendous variation of ranking for the smoke of various materials. A case in point was made in a study of the toxic potency of 14 materials by two methods [33]. It showed (Table I) that the material ranked most toxic by one of the protocols used was ranked least toxic by the other protocol Although neither of these protocols is in common use in the late 1980 s, it illustrates some of the shortcomings associated with small scale toxic potency of smoke tests. 

In recent years there has been much controversy surrounding the impact of smoke toxicity following a fire. This has included discussions regarding means to measure toxic potency, by one of a variety of small-scale methods, and how to use these results to evaluate fire hazard. There has been, in particular, much speculation regarding the hazards due to certain plastics, typically poly(vinyl chloride) (PVC). 

ASTM E 1678 Standard Test Method for Measuring Smoke Toxicity for Use in Fire Hazard Analysis. ASTM International, West Conshohocken, PA. 

ASTM E1678 Standard method for measuring smoke toxicity for use in fire hazard analysis. 

This chapter explains the meaning of the above statements. It describes flammability and smoke/toxic gases evolntion at burning of wood compared to wood-plastic composite (WPC) materials and products of different compositions and profiles. It also explains flammability and fire ratings and indexes as quantitative measures for fire hazard and fire safety, and fire performance characteristics in general of wood and composites. 

Toxicity of smoke is measured by analytical or biological methods [133], and is defined as the action of some agents upon an unprotected individual, which impairs the vital... 

CAL 133. California Technical Bulletin 133 is a test of the fire hazard associated with upholstered furniture (22). The test is carried out by igniting a standard fire source directiy on the piece of furniture being tested. In the most recent version of the test, the fire source is a gas flame. Smoke, heat, and toxic gas emissions are measured dufing the test. A related test, BS 5852, uses various wooden cribs as the fire source (23). 

Over the years plastics users have demanded progressively improving fire performance. By this is meant that plastics materials should resist burning and in addition that levels of smoke and toxic gases emitted should be negligible. That a measure of success has been achieved is the result of two approaches ... 

All fire smoke is toxic. In the past two decades, a sizable research effort has resulted in the development of over twenty methods to measure the toxic potency of those fire smokes (6). Some methods have been based on determinations of specific chemical species alone. Values for the effect (e.g., lethality) of these chemicals on humans are obtained from (a) extrapolation from preexisting, lower concentration human exposure data or from (b) interpretation of autopsy data from accident and suicide victims. The uncertainty in these methods is large since ... 

A second approach to the problem of toxic potency measurement has been to expose laboratory animals, usually rodents, to the smoke from the combustion of small samples of a burning material. Measurement of their response to the smoke leads to one of several biological endpoints, such as the LC50 (the concentration of smoke lethal to 50% of the test animals). In this approach, the animals respond to all the toxicants that are present in the smoke. It presumes that rodent mortality can be related to human mortality or, more simplistically, that the relative toxicity of the smokes will be similar in humans and rodents. However, since the relative contributions of the individual toxic chemicals in the smoke are not determined, a quantitative relationship between man and rodent is impossible using this approach. 

A large number of small-scale tests have been designed to measure the toxic potency of the smoke of materials. These tests differ in many respects the consequence of this is that the relative toxic potencies of smoke resulting from these various tests are different. The tests are not useful,... 

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