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1 FIRE DEATHS IN THE UNITED STATES SCOPE OF THE PROBLEM As a cause of accidental death in the United States, fire is exceeded only by automobile collisions, falls, and drowning.26 The United States and Canada have the highest absolute numbers of fire-related deaths in the world and fire-death rates generally 2-4 times those in Europe.~98 The United States also has one of the highest per capita fire rates. 2 2 2 U.S. fire deaths have been decreasing for the last 20 years, with an overall decrease of about 35% in that period (Figure 1-1). When adjusted for population, the decrease is even more marked--approximately 42% since the early 1950s (Figure 1-2). Throughout the latter period, fires in the home accounted for an average of more than 75% of all fire deaths (Figures 1-1 and 1-2). Most fire deaths occur in one- or two-family dwellings and apartments (Table 1-1). People are most at risk of dying in a fire when they are sleeping6 2 or when their ability to escape is otherwise impaired. In a common type of residential fire, death occurs at night, 2 6 results from the ignition by cigarette of upholstered furniture or bedding (Table 1-2), and involves intoxicating amounts of alcoholic beverages. 3 5 Although most fire deaths occur in residences (one or two per fire), the fires that seem to attract public attention are the dramatic and catastrophic ones that result in the loss of many lives. According to the National Fire Protection Association (NFPA), reported 15
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16 9 8 ~5 In i. o v, ~ 6 7 art.... /l\\/\l\ \ Total Irk \,~\ Home ~ W/~~ \ 5 _ '\r\/ 4 ~ I 1 1 1 , 1 1 1950 1960 1970 1980 1985 Year FIGURE 1-1 Fire deaths in the United States, 19S0-1980, total and home. (Data do not include transport-related Data from National Center for Health fire deaths.) Statistics. 6 0 Census data for 1968 are missing. multiple-death fires (those which resulted in three or more deaths per fire) caused 16.4% of the fire deaths in 1984. On the basis of NFPA data for 1980-1984, loss of life in multiple-death fires has decreased, owing to a reduction in the number of these incidents, rather than in their severity. 62 CAUSES OF FIRE DEATH Accurate data on the causes of deaths associated with fire are difficult to obtain Autopsy is the only means available to determine the cause of death conclusively (i.e., smoke inhalation versus burns), but it does not always provide more definitive information--e.g., was death due to carbon monoxide (CO), to some other toxicant, or to a combination of toxicants? Finally, autopsy is not usually ordered in cases of fire death.
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17 5 4 o 0 0 o lo - it. ~ ~ \~~.. O L I I I I I I I 1950 ., .. ~ Total Home 1 960 1 970 Year 1980 1 985 FIGURE 1-2 Fire deaths per 100,000 population in the United States, 1950-1980, total and home. (Data do not include transport-related fire deaths.) Data from National Center for Health Statistics.i 6 o Census data for 1968 are missing. It is generally accepted that 70-80% of fire deaths result from smoke inhalation. 3 S ~ 3 5 Smoke, as defined by the American Society for Testing and Materials, 3 is n the airborne solid and liquid particulates and gases evolved when a material undergoes pyrolysis or combus- tion. n Indeed, a comprehensive study of fire deaths, performed by the Applied Physics Laboratory of The Johns Hopkins University on the basis of data from Maryland, found that CO, a toxic gaseous component of smoke, was the cause or a contributing cause of 80% of fire deaths (Table 1-3). Alcohol was involved in 40% of deaths. CO, produced by all fires as a component of smoke, is often considered to be the major toxicant produced by fires; it acts by binding to red blood cells and forming carboxyhemoglobin (COHb), which interferes with oxygen transport. In studies of fire death, COHb concentrations of 50-60% are generally accepted as fatal. 3 5 ~ 9 4 (For a complete discussion of CO toxicity, see Chapter 4.)
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18 TABLE 1-1 Fire Deaths by Property Use, United States, 1984a Property Use Residential (total): One- and two-family dwellings Apartments Hotels and motels Other residential Nonresidential structures Highway vehicles Other vehicles Other Total aData from carter. 5 Estimated Number of Civilian Deaths 4,240 3,290 785 120 45 285 530 100 85 5,240 Fraction of Civilian Deaths, 80.9 62~8 15.0 2.3 O.9 5.4 10.1 1.9 1.6 99.9 Besides CO, smoke contains carbon dioxide and can contain oxides of nitrogen, hydrogen cyanide (HCN), hydrogen chloride, sulfur dioxide, acrolein, benzene, phenol, and other compounds.~9 2 These substances, individually or in combination with each other or with CO, can cause immediate or delayed death. They can also impede escape from fire, and thereby increase risk of death, by obscuring vision as a result of eye irritation and lacrimation, by impairing mobility, or by impairing mental acuity. The possibility that toxic gases other than CO cause fire-related deaths has been investigated in several studies. Analysis of samples from 80 victims of the MOM Grand Hotel fire 3 6 revealed that approximately half the victims had COHb concentrations less than 50%; that raises the question of which other toxic factors might have con- tributed to these deaths. Investigations of a jail fire in Johnson City, Tennessee, 37 and of Maryland fire deaths over a 42-month period 3 5 discovered potentially toxic concentrations of HCN in the blood of a number of victims.
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19 TABLE 1-2 Major Residential Fire-Death Scenariosa Item Ignited Fraction of U.S. Ignition Source Fire Deaths, % Furnishings Smoking 27 Trash, apparel Smoking 4 Furnishings, flammable Open flame 11 liquids, apparel Furnishings, flammable Heating and 13 liquids, apparel, cooking interior finish equipment Structural materials, Electric 4 interior finish equipment Flammable liquids, Other 7 apparel Other scenarios, each Variable less than 2% of total 34 100 aData from Benjamin/Clarke Associates, Inc. 32 High HCN concentrations, however, were always associated with high (not necessarily lethal) CO concentrations. Surveys of fire victims in Glasgow have confirmed this, in that both survivors and nonsurvivors had substantial quantities of cyanide in their blood after the fire. 49 Eighteen of the 23 victims of the Air Canada cabin fire in 1983 had sublethal COHb concentrations (less than 50%). Blood concentrations of HCN, however, were lethal in 14 or 19 of the victims, depending on whether one assumes a fatal concentration of HCN to be 1.0 or 2.0 ~g/ml. 3 8 That a number of survivors breathed through wet towels supports the inference that HCN, a hydrophilic agent, was a major factor in causing death. Breathing through wet fabric can in principle reduce the concen- tration of hydrophilic compounds, but not of CO. However, it is not known how many of those who died also breathed through wet towels. (High fluoride concentrations were also found in the victims' blood. The toxicologic sig- nificance of the observed concentrations, however, was
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20 TABLE 1-3 Causes of Fire Deaths (530 Cases)a Cause of Death CO aloneb CO plus cardiovascular disease Burns Unexplained Total aData from Birky et al.35 bCarboxyhemoglobin content over 50%. Fraction of Deaths, 60 20 11 9 100 not established. Exposure to hydrogen fluoride, a hydrophilic acid gas, could also have been reduced by breathing through wet fabric.) THE CONTEMPORARY FIRE ENVIRONMENT Findings like those just described, combined with a growing public awareness of the toxic hazards associated with fire, have led to the belief that today's fires produce combustion products that are more toxic than the fires of 30 or 40 years ago. Some assume that the increased presence of synthetic materials in the built environment causes fires to burn hotter and faster and to produce more toxic smoke than ever before. Although synthetic materials are more prevalent in our work and residential environments than they were 40 or even 20 years ago (Figure 1-3), the national fire-death rate has decreased over the last 30 years. No single factor can explain this trend. For example, the decrease might reflect recent decreases in fire incidence, improvements in firefighting techniques, changes in building fire codes, and the use of home smoke detectors. Although it is possible to document the cause of death in fire victims and potentially possible to identify through pyrolysis/mass spectrometry3 8 the sources of the combustion products inhaled by victims, such studies are infrequent. And the existing data cannot be used to
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21 2,000 cn o ° 1,000 a . _ . _ _ / // PVF / IMPS: PVC / / // / PVF PS PVC 1950 1960 1970 1980 Year FIGURE 1-3 Production of poly(vinyl chloride), poly- styrene, and polyurethane. PUF = total polyurethane production; data from Society of the Plastics Industry. 2 o 7 PS = molded polystyrene production for selected consumer markets; data abstracted from Modern Plastics. 49-~52 PVC = poly(vinyl chloride) film production for selected consumer markets data abstracted from Modern Plastics. l 4 9 - l 5 2 determine trends, because comparative data from the presynthetic era (before 1950) are not available. Post- mortem examination of fire victims for pathologic evidence of exposure to such irritants as HC1 is a fairly new practice; and some techniques for measurement of combus- tion products, such as atomic-absorption spectroscopy for detection of heavy metals and gas chromatography for measurement of blood cyanide, have become widely available only recently. In view of the lack of comparative-pathology studies and of death-rate trends, there is little evidence that modern fires present a greater risk of death than fires of 30 or 40 years ago--either residential fires or large multiple-death fires, such as the Cocoanut Grove fire of 1943.
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22 The hypothesis of a greater toxic hazard in contempo- rary fires might be tested by collecting prospective epidemiologic evidence and exploring potentially variable postexposure health effects in survivors of fires of different kinds. For example, evidence of a change in smoke toxicity could appear as an increased incidence of some pulmonary complications in those exposed to fires that involved greater amounts of synthetic materials. Data for such a study could be drawn from hospital records, insurance-company records, firefighter- association statistics, and so forth. Many factors impinge on the fire problem in the United States; the change in the fuel load of the built environ- ment is only one of them. However, whatever the cause of death, the United States has the highest fire-death rate in the world. An improved understanding of the hazards associated with fires, including toxic hazards, will certainly assist all who must deal with fire and its consequences, be they fire-safety engineers, firefighters, medical personnel, or those who find themselves threatened by fire.
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