Few followup studies to characterize the nature and extent of chronic sequelae have been performed; 74 interpretation of those which have been done is limited by problems related to selected populations selected with respect to types of exposures and extent of illness at presentation for medical carevariability of follownp intervals and measured outcomes, and loss of subjects to followup.
Those larger than 10 Am in diameter are too large to reach the alveoli, so their role in causing parenchymal lung injury is debatable.
Some recover fully within weeks with no permanent sequelae, whereas others have a spontaneous, usually mild, recurrence of pneumonitis several weeks after the exposure. Highly water- soluble gases, if they are also highly reactive with surface components e. The concentration of COHb achieved in blood depends on both the concentration of CO in inhaled air and the duration of exposure.
The impairment is predominantly obstructive, but isolated restrictive and mixed deficits have also been observed. It is the major product of combustion that has been clearly established as contributing to death in fires.
Acute inhalation of HF at lOO ppm can cause death in only a few minutes. Sloughing of the bronchial mucosa can also occur. A wide range of particle sizes, from 0. In sum, the data available are inconsistent and contradictory and show no convincing pattern of excess risk of cancer at specific sites.
But neuropatho- logic examination of human fatalities and the results or animal studies suggest that some brain regions are more vulnerable than others to CO-induced hypoxia insult. The main nonlethal effects of HCl are irritation of the mucous membranes that results in breathing difficulty and lacrimation that obstructs vision, both of which can cause panic.
It can be produced at appreciable concentrations only if the fuel contains both carbon and nitrogen. The extent to which the decrease in visibility caused by particles and soot is a hazard in real fires is, like incapacitation, strongly suspected from anecdotal evidence, but its exact role is largely undetermined.
Even lower concentrations, at or below the threshold of sensory perception and below the current 71 federal occupational standard 5 ppmcan cause reversible impairment of respiratory functions.
This deteriora- tion was characterized by disorientation, confusion, excitement, restlessness, defective motor control, and even frank psychosis.
Ginsberg 7 reviewed the neuropathologic consequences of cyanide intoxication. Smoke consists of particles sootgases e. Chronic pulmonary function changes attributed to s repeated smoke exposure have been found in three studies of firefighters.
That shifts the oxyhemo- globin dissociation curve to the left; as a result, tissue O2 tensions must fall to lower than normal for the O2 to be released from hemoglobin. 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.
Neuropathologic examination of his brain showed marked destruction of several cortical layers and damage to the hippocampus, basal ganglia, and cerebellum. After a few hours, pul- monary edema might set in.
Recent reviews contain more detailed and comprehensive treatments of the subject. Among patients with both smoke inhalation and surface burns, the pul- monary function abnormalities were more severe than in those with either alone, and decrements of function were still resolving at the 5-month followup.
The most serious potential hazard, of course, is the combination of a mixture of combustion products with high temperatures that can increase their toxicity. The lesions produced in the brain closely resemble those seen after CO exposure.
Firefighters have been a useful cohort for investigations of respiratory morbidity. CO2 also contributes to an abnormal acid-base balance when inhaled at the concentra- tions and for the durations common in fires.
The authors reported that CO at 5, ppm was lethal in 30 min. Inhalation of HCN can be rapidly fatal. Similarly, although data are insufficient for drawing firm conclusions, the combination of numerous respiratory irritants can be expected to induce toxic pulmonary effects not anticipated on the basis of the effects induced by exposure to any single toxicant at lower concentrations.
Excess cancer risk has been suggested in studies of firefighters who sustained chronic exposures, but, although plausible, remains unmeasurable among single-episode victims.
The relative contribution of each to the overall hazard depends on the physical charac- teristics of the fire, namely, heat release rate, fuel source, and oxygen supply.
Associated symptoms dyspnea at rest and on exertion and disability can be severe.Hazards of combustion products: Toxicity, opacity, corrosivity, and heat release: to develop a coherent and comprehensive set of fire safety standards and guidance documents for life safety. Shaoxiang Li, Yuanxiang Gu, Influence of ferric hydroxide on smoke suppression properties and combustion behavior of intumescent flame retardant.
(5) Toxicity of combustion product gases Toxic hazards are listed last because of the time factor involved in physiological dam- age. hazards to survival in airplane crashes studied the factors that affect passengers under fire conditions by conducting full-scale crashes of transport and cargo airplanes.
CHEMICAL AND GAS HANDLING The generation of flammable vapours during cargo transfer Chapter 41 - Fire BASIC CONCEPTS Dougal Drysdale The Chemistry and Physics of Fire Fire is a manifestation of uncontrolled combustion It involves combustible.
Read chapter 4 Hazards Associated with Fires: Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book.
Fire Protection Research Foundation report: "Fire Hazards of Exterior Wall Assemblies Containing Combustible Components" (PDF) Author: Nathan White, CSIRO, Highett, VIC Australia and Michael Delichatsios, FireSERT, University of Ulster, Jordanstown, Northern Ireland Date of issue: June Introduction.
Many combustible materials are used today in commercial wall assemblies to improve. ENVIRONMENTAL EFFECTS AND HAZARDS IN COMBUSTION Combustion is a hazard, and, besides the many services it provides to humankind, it may cause nuisance (e.g.
noise, smoke), damage to property (deformations, loss of strength, burnings and explosions), and damage to .Download