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Animal Models
Published in Brian J. Lukey, James A. Romano, Salem Harry, Chemical Warfare Agents, 2019
Animal incapacitation or impairment of escape is considered to be among the most important endpoints, as it mirrors human escape capability when exposed to hazardous chemical agents. A number of incapacitation models were developed to study this endpoint in the context of the combustion toxicology of products (Chaturvedi et al., 1993, 1995; Crane et al., 1989; Hartzell, 1989; Hartzell et al., 1985; Levin et al., 1985; Pauluhn, 2004; Speitel, 1995). This field of toxicology is engaged with the hazard and risk assessment of fire effluents, which constitute mixtures of asphyxiant and/or irritant gases (ISO 13571, 2012). Multiple rodent and non-human primate models were devised for the measurement of loss of motor function and consciousness following exposure to the asphyxiant gases carbon monoxide (CO) and hydrogen cyanide (HCN). The decline in behavioral task performance from multiple models has been compared in detail elsewhere (Pauluhn, 2016a,b; Speitel, 1995). Equation 38.1 simulates the impact of increased CO2 on the impairment of escape as conceptualized and modified by Speitel (1995).
Occupational respiratory diseases
Published in Louis-Philippe Boulet, Applied Respiratory Pathophysiology, 2017
Louis-Philippe Boulet, Marc Desmeules
Asphyxia is an acute clinical process that induces hypoxia or anoxia, a defect in oxygenation of cells of the organism. There are two types of asphyxiant gases: simple and bioactive. Simple asphyxiant products such as nitrogen, CO2, methane, and anesthetic gases remove oxygen from inhaled air. They do not have a specific toxicity. They cause a fall in the inspired PO2 and arterial hemoglobin desaturation. If the individual survives, asphyxia can leave some sequelae, neurological mainly, according to its duration, to the severity of hypoxia and extension of tissue damage.
Oxygen deficiency hazard in confined spaces in the steel industry: assessment through predictive models
Published in International Journal of Occupational Safety and Ergonomics, 2021
Elena Stefana, Filippo Marciano, Paola Cocca, Diana Rossi, Giuseppe Tomasoni
In addition to the confined space size, another aspect determining the criticality of an O2-deficient atmosphere regards the characterization of different potential releases. Safety managers should focus on their flow rates, duration and occurrence. Higher asphyxiant gas flow rates may result in more severe cases and scenarios. This severity increases mostly if accidental leaks occur in a confined space. Indeed, this type of release is often sudden, inadvertent and uncontrolled, producing a rapid O2 decrease. Moreover, confined spaces typically present in the steel industry often lack ventilation and/or extraction systems, increasing the probability of O2 deficiency and reducing the possibility to restore a safe indoor air composition. The release duration should also be analysed in order to comprehend its nature, i.e., whether it can be instantaneous, temporary or continuous. In this article, we investigated continuous releases and thus the O2 reduction is gradual. In the case of a leak that instantaneously releases a gas volume similar to the total volume released during a continuous leak, ODH can occur rapidly, exposing workers to an immediate asphyxiation risk. For instance, if the flow rate leaked accidentally for 1 h in Scenario 2 was instantly released in 1 s at the beginning of the exposure period (assuming a release volume equal to 12.5 m3 with a probability of 0.15), the operator would be subjected to air containing an O2 level of only 10.20%. Therefore, in all these situations, leak prevention and detection should be matters of priority. In the scenarios presented in this article, undetected releases and leakages are assumed. Their early detection could prevent or interrupt the exposure, and thus modify the simulation results.