Fire conditions for smoke toxicity measurement

Abstract

This paper identifies those fire conditions most often present when smoke toxicity is the cause of death. It begins with a review of the evidence that smoke-inhalation deaths are in the majority in fire fatalities in the United States. Next, there is an analysis of the evidence from the national fire experience showing the connection between post-flashover fires and smoke-inhalation deaths. Third is a presentation of real-scale fire test results demonstrating that postflashover conditions are necessary to produce enough smoke to cause smoke-inhalation deaths in the cases where they actually occur. The fourth component is a sampling of results from computer simulations of fires, affirming and broadening the results from the fire tests. It is concluded that smoke-inhalation deaths occur predominantly after fires have progressed beyond flashover. This conclusion then provides a focus for smoke toxicity measurement in particular and fire hazard mitigation in general. INTRODUCTION AND PURPOSEFor decades, students of the United States fire problem have known that most fire deaths are due not to burns but to toxic gas effects, oxygen deprivation, and other effects of what has been loosely referred to as 'smoke inhalation'. ' -4 What has been less well understood is the fire circumstances under which smoke-inhalation effects are most important in causing these deaths. This information has considerable potential relevance to an understanding of the relative roles of different products in contributing to lethal conditions in fires. This in turn underlies fire performance evaluation, whether by laboratory testing of products, computer-based calculation or, most likely, a combination of the two.The purpose of this paper is to identify, through analysis of national fire incidence data and the results of fire tests and computer models of fires, those fire conditions most often associated with deaths due to one-time inhalation of fire smoke. (The paper does not address deaths resulting from chronic exposure to smoke.) These diverse sources of information all clearly indicate that in the United States deaths occur predominantly after fires have progressed to or beyond flashover and usually involve victims located in a room other than the room or area where the fire originated. This finding has implications for the fire conditions most relevant to fire toxicity assessment in general and smoke toxicity measurement in particular. BACKGROUND

Fire safety of passenger trains, phase I:

“…Hirschler showed that materials with low HRR also possess low smoke emission [114]. Although examples of typical fire histories demonstrate that fire deaths are primarily caused by toxic gases, the toxicity of the vast majority of common construction materials is similar [115]. Thus, the relative toxicity of combustion gases plays a smaller role than the HRR of a fire.…”

“…HRR is the key indicator of real-scale fire performance of a material or construction, including ignition, flammability [71], and smoke emission generation [115] is the only test method that attempts to replicate end-use conditions.…”

El Diseño Basado en Prestaciones frente al Incendio de las Estructuras de Edificación

“…Las pinturas intumescentes, como único sistema pasivo posible, reaccionan a los incrementos térmicos superiores a los 200º C aproximadamente. El análisis prestacional determina que el colapso de las cerchas de cubierta se puede llegar a producir para unas temperaturas de la estructura inferiores al valor de reacción del producto químico, por lo tura adiabática en una superficie sólida es aquella para la cual el flujo de calor neto es nulo [3].…”

Smoke component yields from Bench-Scale Fire Tests : 4. Comparison with Room Fire Results

“…Furthermore, the generation of carbon monoxide (CO), the most common toxicant, can vary by orders of magnitudes, depending on the fire conditions. 10 An analysis of the U.S. fire fatality data 11 showed that postflashover fires comprise the leading scenarios for life loss from smoke inhalation. Thus, it is most important to obtain data regarding the generation of harmful species under postflashover (or otherwise underventilated) combustion conditions.…”