Fire and Smoke Understanding the Hazards (1986) / Chapter Skim
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4 Hazards Associated with Fires
4 Hazards Associated with Fires
Pages 62-77
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From page 62... ...
Although most fire deaths are due to smoke inhalation, many are caused by burns from the heat of the flame itself .6 3 6 4 2 0 3 A skin temperature of about 45°C is associated with pain. 2 ~ 4 Burn injury caused by the inhalation of air heated to 150 °C or higher is ordinarily confined to the oropharynx and upper airway (above the vocal cords)
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From page 63... ...
, volatilized organic molecules of varied complexity, aerosols, and free radicals. The extent to which these components contribute to the overall hazard associated with smoke is discussed briefly below.
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From page 64... ...
Some investigators believe that such hydrophilic pyrolysates as hydrogen chloride (HC1) can adhere to smoke particles and thus be transported into the tracheorespiratory tree, where they can directly damage membranes and cause edema.58 However, estimates from laboratory modeling suggest that less than 2% of the predicted amount of HC1 produced is adsorbed on soot.~27 How much of this reaches the lower airways is uncertain.
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From page 65... ...
In addition to its effects on the respiratory center, CO2 at sufficient concentrations can cause headache, somnolence, mental confusion, hyporeflexia, lassitude, revere necrologic disturbances, such and eventually more _ as tremors, flaccid paralysis, unconsciousness, and eventually, death.~° 6 Carbon Monoxide Carbon monoxide (CO) is an odorless and colorless gas.
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From page 66... ...
A partial explanation for the wide disparity in the behaviorally disruptive CO threshold is that organisms respond to hypoxia challenge by increasing cerebral blood flow202 and that this compensatory mechanism can sustain function only up to a point, after which a precipitous decline might occur.
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From page 67... ...
In a more extensive examination of human brain injury after various hypoxia insults, Ginsberg 7 concluded that lesions of the white matter were prominent. Monkeys exposed to severe CO intoxication exhibited essentially the same neuropathologic pattern.
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From page 68... ...
are readily absorbed and cause injury to proximal mucosal surfaces and the upper respiratory tract. Deposition of insoluble gases (e.g., some oxides of nitrogen)
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From page 69... ...
A serious but rare complication is bronchiolitis obliterans, in which spontaneous deterioration begins about 4-6 weeks after injury and pulmonary function shows a restrictive or mixed obstructive-restrictive process. Respiratory failure and death can ensue; there are usually permanent residue among those who recover.89 Hyrdrogen Chloride Airborne HCl exists in the anhydrous state and as an aerosol.
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From page 70... ...
There is some evidence, mainly from animal experiments, that a single brief exposure can cause persistent lung damage, such as emphysema and interstitial fibrosis. Severe discomfort with lacrimation, coughing, and respiratory distress is induced by somewhat less intense exposures than those requiring hospitalization, and a milder pulmonary edema with reversible respiratory impairment is possible.~45 Single exposures to NO2 at concentrations that cause slight, but tolerable, discomfort in humans have been shown in animal experiments to cause a reversible increase in susceptibility to respiratory infection and aggravated reactions to allergens.
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From page 71... ...
, subacute exposures cause severe eye and respiratory tract irritation. After a few hours, pulmonary edema might set in.
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From page 72... ...
Other chemicals, such as free radicals, have recently been identified as potentially lethal, but difficulties in detecting them in human victims leave their contribution to fire fatalities uncertain. The most serious potential hazard, of course, is the combination of a mixture of combustion products with high temperatures that can increase their toxicity.
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From page 73... ...
Causes of death at the fire scene include heat, burns, and necrologic and cardiorespiratory collapse 43 79 132 153 154 180 230-232 EARLY POSTEXPOSURE EFFECTS Early postexposure effects are defined as those which are seen after rescue or entry into the emergency care system and in the resuscitation and shock phase -- a period of up to several days. Myocardial infarction can be precipitated by the physical and psychologic stresses of the fire.
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From page 74... ...
Recent animal studies of pulmonary effects of wood smoke and thermal decomposition products of plasticized poly(vinyl chloride) have shown that smoke from Douglas fir diminished ventilatory response to 10% CO2.
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From page 75... ...
Caution needs to be applied, however, in generalizing results from studies in this group, which faces recurrent exposures and different exposures in postfire overhauls, to the population of victims of single exposures. Although a number of studies among firefighters have identified acute pulmonary complications of smoke inhalation, the reported chronic sequelae are variable.
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From page 76... ...
studied the mortality experience of Boston firefighters employed from 1915 to 1975.~ 5 6 The possibility that firefighters have excess cancer risks has been suggested by a number of other epidemiologic studies, with no consistent pattern of excess identified. These studies reported increases in brain cancer and lymphatic and hematopoietic cancers, 44 in lung cancer,70 ~79 and in gastrointestinal cancer.7 6 More recent studies, by Feuer and Rosenman7 6 and N
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From page 77... ...
Some studies have shown an absence of excess cancer risk, 4 2 ~ 5 9 and others have shown excesses of lung, gastrointestinal, hematopoietic, and brain cancers.~° 144 179 SUMMARY The most studied and best recognized chronic sequelae of exposure to fire smoke are in the respiratory system. Smoke inhalation, with and without burn injury, has been demonstrated to cause persistent and sometimes irreversible impairment in pulmonary function.
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