Aim: The aim of this paper is to present the state of the art on toxicity assessment of combustion products which may occur during indoor fire development. The authors described the results of studies carried out by research institutions all over the world, with a particular focus on the determination of combustion products and parameters measured during such studies which have an impact on human life and the environment. An outline was also presented of the fundamental and theoretical aspects of mechanisms of toxic combustion product formation and certain factors contributing to such formation during combustion processes as well as critical parameters which may prove essential for the assessment of combustion product toxicity.
Introduction: Most of deaths caused by fires result from the impact of toxic gases on the human body. Gaseous combustion products, such as, carbon monoxide and hydrogen cyanide, are the major components of lethal toxins. The combustion products also include other asphyxiant or irritant gases. Their action in the respiratory system, in contrast to carbon monoxide, consists mainly in causing difficulty of breathing as a result of the produced mucus. And their eye-irritating effect makes it difficult to escape from the place of the fire given the limited visibility caused by smoke. Due to the above, there is a need for detailed research on the toxicity of combustion products of specific construction materials and products that are commonly used in architecture and construction. The materials and construction products in question include electric cables, whose external coatings often contain a whole range of polymers and other plastics. Each fire is characterised by specific stages of development. The first of them will almost always be a slow thermal breakdown. The temperature at which the material is subjected to thermal decomposition is also important for the type and amount of chemicals released.
Methodology: The paper was prepared on the basis of the state of the art taken from the available literature and research results on determination methods of toxic combustion products in particular during indoor fire development.
Conclusions: A large number of known irritant chemicals have been found in the fire environment. Irritant chemicals are formed during the pyrolysis and oxidation of materials, and the combustion products of various materials are often very similar. For many organic materials, and especially for simple hydrocarbon polymers, such as polypropylene or polyethylene, the main pyrolysis products consisting of various hydrocarbon fragments are harmless. Polypropylene pyrolysis products include ethylene, ethane, propene, cyclopropane, formaldehyde, butane, acetaldehyde, toluene and styrene are formed, which do not affect primates. When products are oxidised during flameless decomposition in the air, some of them are transformed into very irritating products. Such an atmosphere proved strongly irritating to mice and primates. In addition to toxic fire gases, the loss of basic vital functions in humans during a fire can also be caused by smoke. It not only limits visibility, but also contains fragmented matter, which is small enough to pose a threat to the respiratory system. The particle size distribution depends on the material, temperature and stage of the fire. The typical size of spherical droplets for smoldering is 1 μm, while irregular soot particles are considerably larger, harder to identify and heavily dependent on the measurement and sampling methods.
Keywords: fire toxicity, combustion products, fire effluents
Type of article: review article