mpact of assignment, suppression tactics on thermal burden
Firefighters’ thermal burden is generally attributed to high heat loads from the fire and metabolic heat generation, which may vary between job assignments and suppression tactic employed. Utilising a full-sized residential structure, firefighters were deployed in six job assignments utilising two attack tactics (1. Water applied from the interior, or 2. Exterior water application before transitioning to the interior). Environmental temperatures decreased after water application, but more rapidly with transitional attack. Local ambient temperatures for inside operation firefighters were higher than other positions (average ~10–30 °C). Rapid elevations in skin temperature were found for all job assignments other than outside command. Neck skin temperatures for inside attack firefighters were ~0.5 °C lower when the transitional tactic was employed. Significantly higher core temperatures were measured for the outside ventilation and overhaul positions than the inside positions (~0.6–0.9 °C). Firefighters working at all fireground positions must be monitored and relieved based on intensity and duration.
Heat stress is one of the most common challenges that firefighters routinely encounter. Because firefighters perform strenuous work while wearing heavy, insulating personal protective equipment (PPE), a rise in body temperature almost always accompanies firefighting activity. High heat loads from the fire can also add to the heat stress experienced by firefighters. The physiological and thermal strain of firefighting activities have been documented based on simulated fireground work. The change in core temperature associated with firefighting activities has been reported by several research groups.
Firefighting involves strenuous work that leads to maximal or near-maximal heart rates (HR) and, in some cases, rapid changes in core temperature, reported average changes of 0.70 °C during short bouts of firefighting activity typical of residential ‘room and contents’ fires. The researchers noted that repeated bouts of firefighting or the use of multiple cylinders of air is associated with further increases in body temperature.
It is important to note, however, the vast majority of work that has been done characterising the thermal stress of firefighting has occurred during training fires or in controlled laboratory conditions. Training fires differ considerably from residential fires in terms of the geometry of the structure, building materials and fuel loads. Because of these factors, firefighters may experience different thermal environments, as well as different chemical exposures, during actual fires in residential buildings than in a training burn. Recent measurement of ambient temperatures inside common structure fires have further detailed risks posed by firefighting activities in modern structure fires. However, these studies have not included human subjects. Portable thermal data acquisition systems carried by firefighters have been used to characterise risks faced by firefighters in ive-fire training scenarios and historically for firefighting activities that were largely exterior focused. However, to date, these data acquisition systems have not been deployed in structure fire scenarios with typical residential fuel packages or linked to data from physiological status monitoring.