Published:16 Oct 2015
The toxic effects of combustion products are a major cause of human morbidity and mortality. We are all exposed, every day, to air pollutants produced by the combustion of organic materials, while significant numbers of people suffer severe injury and death from fires. The hazards range from continuous exposure to low concentrations of toxic vapours and particulates, both outdoors and indoors, throughout our lives, to single short-duration exposures to very high concentrations during fires.
In order to evaluate and find ways to mitigate these hazards it is not sufficient or practical to consider the toxicity of combustion products in isolation, but rather in the context of systems involving the source terms (fires or other combustion processes), the dispersal of effluent plumes and the dynamics of human exposure and toxicity.
In compiling this book we have been very fortunate to obtain chapters contributed by leading international experts in the relevant fields. In addition to benefitting from this eminent multiple authorship we have attempted to provide a comprehensive and coordinated guide, which we hope will be of value both to those wishing to form a general understanding of the subject, and to regulators, forensic investigators, clinicians and engineers involved in practical assessments of hazard and risks from combustion products. Chapter 1 provides an overview of the subjects covered, and throughout the book chapters on specific topics we have provided frequent cross-references to integrate between relevant sections of different chapters.
In the first section of the book we have addressed the formation and dispersal of combustion products. It is a common misconception that one can identify “toxicity” as a discrete property of specific substances such as wood or diesel fumes, but this cannot be farther from the truth. In reality the combustion products from individual fuels consist of a complex mixture of many individual toxic substances in the form of vapours and particulates. The composition of the effluent plume depends partly on the elemental and molecular composition of the burning fuel, but very much upon the combustion conditions, so that the yields and concentrations of key toxic products, such as carbon monoxide, can vary by several orders of magnitude. Both the fire size and combustion conditions change considerably during fire development and the human exposure conditions further depend on the dynamics of air entrainment and plume dispersal. These issues are covered in the first section, including descriptions of fire physics and chemistry, models for the calculation of rates of formation and composition of fire plume from different fuels, and fire conditions and their dispersal both within buildings and in the outside environment.
The effects on exposed subjects in different locations relative to a fire also vary at different locations throughout an exposure. For fire victims inside buildings or vehicles the sequence of toxic hazards usually begins with the immediate pain and incapacitating effects of exposure to visually obscure smoke, containing a range of irritant acid gases and particulates, followed by asphyxiation from gases, including carbon monoxide and hydrogen cyanide, complicated by heat exposure and burns. Following exposure, another set of effects include chemical lung injury, burns, and neurological and cardiovascular effects. Evaluation of these hazards therefore requires assessment of the source term and exposure conditions, as well as the subsequent sequence of physiological and pathological effects. The toxicology of these effects and methods for their assessment are presented in the second section, with clinical aspects of toxicology and management in the third section.
Assessing the effects of exposure to widely dispersed fire effluent plumes or deposited pollutants in the outside environment presents another set of challenges. Unlike the life-threatening effects of exposures during fires inside buildings, the health effects of both single and repeated exposures to dilute smoke plumes or combustion products dispersed into the environment are more subtle, ranging from acute nuisance odour to long term health hazards such as cardio-respiratory diseases and carcinogenicity. Aspects of these are also described in terms of their formation and dispersal in the first section and their toxicity in the second section. The third, fourth and fifth sections discuss aspects of clinical management and assessment, examples of some specific large conflagration incidents and the public health aspects of fire incident management.
With diverse coverage, and edited and authored by recognised experts in the field, it is intended that this book will provide an essential text for those working in toxicology, combustion science, public health, safety engineering, forensic fire investigation and environmental research.