Smoke and Combustion Products

Exposure to smoke and complex combustion products is a major source of death and disease in two major populations: residents of burning structures and firefighters attempting to extinguish them. Seventy-six percent of the people that died in fires in their residential structures in 1990 died from the inhalation of toxic combustion products, not from burns (J. R. Hall and B. Harwood, Smoke or burns—which is deadlier? NFPA J., 38–43 (1995)). This percentage has been rising by about one percentage point per year since 1979. Although total deaths in fires are declining, the percentage attributed to smoke inhalation has increased. The majority of deaths and chronic diseases in residential firefighters have also been attributed to smoke exposure (T. L. Guidotti, Occupational mortality among firefighters: assessing the association. J. Occup. Environ. Med., 37, 1348–1359 (1995)). The area of research termed combustion toxicity has evolved to study the adverse health effects caused by smoke or fire atmospheres. According to the American Society for Testing and Materials (ASTM), smoke consists of “the airborne solid and liquid particulates and gases evolved when a material undergoes pyrolysis or combustion” (Annual Book of ASTM Standards, Vol. 04.07, E176, ASTM, 1996, pp. 496–500) and therefore, includes combustion products. In this chapter, a fire atmosphere is defined as all the effluents generated by the thermal decomposition of materials or products regardless of whether that effluent is produced under smoldering, nonflaming, or flaming conditions. The objectives of combustion toxicity research are to identify potentially harmful products from the thermal degradation of materials, to determine the best measurement methods for the identification of the toxicants as well as the degree of toxicity, to determine the effect of different fire exposures on the composition of the toxic combustion products, to predict the toxicity of the combustion atmospheres based on the concentrations and the interaction of the toxic products, and to establish the physiological effects of such products on living organisms. The ultimate goals of this field of research are to reduce human fire fatalities due to smoke inhalation, to determine effective treatments for survivors, and to prevent unnecessary suffering from cancer and other adverse health outcomes caused by smoke inhalation. Other reviews of various aspects of this subject can be found in the following references: B. C. Levin, Combustion toxicology, in P. Wexler, ed., Encyclopedia of Toxicology, Vol. 1, Academic Press, San Diego, 1998, pp. 360–374. G. L. Nelson, ed., Fire and Polymers II: Materials and Tests for Hazard Prevention, ACS Symposium Series 599, American Chemical Society, Washington, DC, 1995. National Research Council and National Materials Advisory Board, Fire- and Smoke-Resistant Interior Materials for Commercial Transport Aircraft, Publication Number NMAB-477-1, National Academy Press, Washington, DC, 1995. D. Purser, Smoke toxicity, in National Research Council and National Materials Advisory Board, Improved Fire and Smoke-Resistant Materials for Commercial Aircraft Interiors: A Proceedings, Publication Number NMAB-477-2, National Academy Press, Washington, DC, 1995, pp. 175–195. B. C. Levin, New research avenues in toxicology: 7-gas N-gas model, toxicant suppressants, and genetic toxicology. Toxicology 115, 89–106 (1996). Keywords: combustion; fire deaths; firefighters; fire hazard; fire risk; particulates; predictive models; smoke; suppressants; test methods; toxic gases; toxicity assessment; toxic potency