AbstractIntroductionIn the course of their duties, firefighters risk heat stroke and other medical conditions due to exertion in high-temperature environments. Infrared tympanic temperature measurement (T_Tym) is often used by Emergency Medical Services (EMS) to assess the core body temperature of firefighters. The accuracy of T_Tym in this setting has been called into question.Hypothesis/ProblemThis study aimed to examine the accuracy of T_Tym for core body temperature assessment at emergency firefighting events compared with gastrointestinal temperature measurement (T_GI) as measured by ingestible thermometers.MethodsForty-five (42 male, three female) professional urban firefighters from an Australian fire service completed two 20-minute work periods in a 100°C (± 5°C) heat chamber while wearing personal protective clothing (PPC) and breathing apparatus (weighing approximately 22 kg). Measurements were taken immediately before entering, and on exiting, the heat chamber. Tympanic temperature was assessed by an infrared tympanic thermometer and T_GI was measured by ingestible sensor and radio receiver.ResultsComplete data were available for 37 participants. Participant temperatures were higher on exiting the heat chamber than at baseline (T_Tym: 35.9°C (SD=0.7) vs 37.5°C (SD=0.8); T_GI: 37.2°C (SD=0.4) vs 38.6°C (SD=0.5)). Tympanic temperature underestimated T_GI on average by 1.3°C (SD=0.5) before entering the chamber and by 1.0°C (SD=0.8) following the exercise. Using pooled data, the average underestimation was 1.2°C (SD=0.7).ConclusionTympanic thermometers cause an unreliable measure of core body temperature for firefighters engaged in fire suppression activities. Accurate and practical measures of core body temperature are required urgently.KeeneT, BrearleyM, BowenB, WalkerA. Accuracy of tympanic temperature measurement in firefighters completing a simulated structural firefighting task. Prehosp Disaster Med. 2015;30(5):461–465.