The Management of Heat Stress for the Firefighter: A Review of Work Conducted on Behalf of the Toronto Fire Service

Abstract

This report provides a summary of research conducted through a grant provided by the Workplace Safety Insurance Board of Ontario. The research was divided into two phases; first, to define safe work limits for firefighters wearing their protective clothing and working in warm environments; and, the second, to examine strategies to reduce the thermal burden and extend the operational effectiveness of the firefighter. For the first phase, subjects wore their protective ensemble and carried their self-contained breathing apparatus (SCBA) and performed very light, light, moderate or heavy work at 25°C, 30°C or 35°C. Thermal and evaporative resistance coefficients were obtained from thermal manikin testing that allowed the human physiological responses to be compared with modeled data. Predicted continuous work times were then generated using a heat strain model that established limits for increases in body temperature to 38.0°C, 38.5°C and 39.0°C. Three experiments were conducted for the second phase of the project. The first study revealed that replacing the duty uniform pants that are worn under the bunker pants with shorts reduced the thermal strain for activities that lasted longer than 60 min. The second study examined the importance of fluid replacement. The data revealed that fluid replacement equivalent to at least 65% of the sweat lost increased exposure time by 15% compared with no fluid replacement. The last experiment compared active and passive cooling. Both the use of a mister or forearm and hand submersion in cool water significantly increased exposure time compared with passive cooling that involved only removing most of the protective clothing. Forearm and hand submersion proved to be most effective and produced dramatic increases in exposure time that approximated 65% compared with the passive cooling procedure. When the condition of no fluid replacement and passive cooling was compared with fluid replacement and forearm and hand submersion, exposure times were effectively doubled with the latter condition. The heat stress wheel that was generated can be used by Commanders to determine safe work limits for their firefighters during activities that involve wearing their protective clothing and carrying their SCBA.

Development of a perceptual hyperthermia index to evaluate heat strain during treadmill exercise

“…30 Thermal insulation and evaporative resistance increases the physiological and psychological strain on the wearer. 44 These conditions can occur during both prolonged light work and shorter bursts of high intensity work. Ambient conditions may impose another strain on the wearer in addition to that of the protective clothing.…”

Microstructured Arrayed Microfluidic Waveguide Structure for Infrared Radiation Focusing and Transfer

“…One-and two-dimensional interferometric lithography processes have successfully been used to fabricate microfluidic channels of cross-section areas as small as 10x10 µm 2 . High-resolution imprint lithography has recently emerged as a very promising technology for the fabrication of Integrated Circuits (ICs) and nanofluidic devices [7].…”

“…The heat removal problem affects a number of important occupations throughout the world, including the military, mining industry and fire service, all which require a workforce to wear protective clothing not conducive to sweat evaporation [2,3,4,5]. Indeed, the creation of a practical heat removal device for these workers has challenged scientists to date.…”

Protective clothing ensembles and physical employment standards

“…Current work and rest schedules for the Toronto Fire Service (McLellan and Selkirk 2006) were established using 38.5°C as the ceiling for the core temperature increase while wearing firefighting PCE. Higher limits of 39.0°C were used to establish similar guidelines for personnel wearing military nuclear, biological, and chemical PCE (Aoyagi et al 1994).…”

“…As a result, the added heat strain of wearing PCE could be a daily occurrence that would impact the manner that recruits or incumbents conduct job-related tasks. One option to manage this heat strain of wearing PCE is to develop specific work and rest guidelines, which has been done for firefighter (McLellan and Selkirk 2006) and military (Aoyagi et al 1994) PCE. These guidelines, however, are based on mean responses generated from both sedentary and very active participants (Aoyagi et al 1994;Selkirk and McLellan 2004) and may overestimate work times for the less aerobically fit individual.…”