Fire smoke toxicity

ABD 0031 Airbus Directives (ABD) and Procedures for Fire-Smoke-Toxicity (FST). Airbus Industries. 

FIGURE 17.5 Diagram of fire smoke toxicity test based on NBS smoke chamber. (From Hull, T.R. and Paul. K.T., Fire Saf. /., 42, 349, 2007. With permission.)... 

K.T. Paul, T.R. Hull, K. Lebek, and A.A. Stec, Fire smoke toxicity The effect of nitrogen oxides, Fire Safety Journal, 43, 243-251, 2008. 

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. 

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 ... 

LEVIN GANN Toxic Potency of Fire Smoke... 

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. 

It is well known that hydrogen cyanide can be liberated during combustion of nitrogen containing polymers such as wool, silk, polyacrylonitrile, or nylons (1, 2). Several investigators have reported cyanide levels in smoke from a variety of fires (3, 4, 5). The levels reported are much below the lethal levels. Thus the role of cyanide in fire deaths would seem to be quite low. However, as early as 1966 the occurence of cyanide in the blood (above normal values) of fire victims was reported (6). Since then many investigators have reported elevated cyanide levels in fire victims (7-13). However, it has been difficult to arrive at a cyanide blood level which can be considered lethal in humans. In this report the results of cyanide analysis in blood of fire victims are reported as well as the possibility that cyanide may, in some cases, be more important than carbon monoxide as the principal toxicant in fire smoke. 

With so many other toxicants present in fire smoke there must be some which reduce the toxicity of HCN. Similar findings were also found for cynomolgus monkeys exposed to smoke containing HCN vs. HCN alone (14). 

General Principles of Fire Hazard and the Role of Smoke Toxicity... 

Fire hazard is a combination of several properties, including ignitability, flammability, flame spread, amount of heat released, rate of heat release, smoke obscuration and smoke toxicity. 

Thus, smoke toxicity is often very closely associated simply with the mass loss rate, since the toxicity in a fire scenario will be primarily a function of the mass ofsmoke per unit volume and per unit time being emitted into the ambient atmosphere. 

Fire safety in a particular scenario is improved by decreasing the corresponding level of fire risk or of fire hazard. Technical studies will, more commonly, address fire hazard assessment. Fire hazard is the result of a combination of several fire properties, including ignitability, flammability, flame spread, amount of heat released, rate of heat release, smoke obscuration and smoke toxicity. 

Jones, W. W., A Model for the Transport of Fire. Smoke and Toxic Gases (FASTI NBSIR 84-2934, Natl Bur. Stands (September), 1984. 

Fire hazard is associated with a variety of properties of a product in a particular scenario [1]. It is determined by a combination of factors, including product ignitability, flammability, amount of heat release on burning, rate at which this heat is released, flame spread, smoke production and smoke toxicity. 

Techniques are available to quantify the generation of smoke, toxic and corrosive fire products using the NBS Smoke Chamber (15), pyrolysis-gas chromatography/mass spectrometry (PY-GC-MS) (J 6), FMRC Flammability Apparatus (2,3,5,17,18), OSU Heat Release Rate Apparatus (13) and the NIST Cone Calorimeter (JJO. Techniques are also available to assess generation of 1) toxic compounds in terms of animal response (19), and 2) corrosive compounds in terms of metal corrosion (J 7). In the study, FMRC techniques and AMTL PY-GC-MS techniques were used. 

Generation of Smoke, Toxic and Corrosive Fire Products. Smoke, toxic and corrosive products are generated in fires as a result of vaporization, decomposition and combustion of materials in the presence or absence of air. 

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). 

Address the issue of PVC fire properties, including smoke toxicity and hydrogen chloride decay. 

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