Published works

The physiological burden of Urban Search and Rescue (USAR) operations in the tropics is poorly understood. Sixteen trained USAR personnel (90.4kg, 1.81m, 39.6yrs) participated in a 24hr simulated exercise conducted during November in Northern Australia. Participants provided written informed consent for this study and were recruited from NT Fire and Rescue and QLD Fire and Emergency Services, resulting in 8 heat acclimatised (HA) and 8 non-heat acclimatised (NHA) responders. Physiological monitoring included core temperature (Tc) through the use of ingestible thermometers based on established protocols1. The initial 4 hour shift (ambient 34.0oC, 48% relative humidity) resulted in 15 of the 16 participants exceeding the ISO9886 Tc safe working limit of 38.5oC. From the 80th minute of the initial shift, HA sustained a significantly (p<0.01) higher Tc (38.6oC) than the NHA cohort (38.1oC) despite both groups perceiving their body temperature equally as hot. Following the initial shift, only 2 participants exceeded Tc 38.5oC, likely due to crews suffering from the heat strain endured during the first 4 hours. Seven (5 NHA, 2 HA) of the 16 participants presented to medical staff during this period with symptoms of headache, nausea and exhaustion. Pacing of effort was apparent for non-heat acclimatised personnel. Year round heat acclimatisation through physical training is likely to improve operational capability of deployed teams. More frequent rotation of crews to permit monitoring through a rehabilitation sector, inclusive of active cooling options, is likely to reduce physiological strain and heat related illness during deployment to tropical regions.