In 2013, over 7,500 firefighters were injured during training related activities, including highrisk, but necessary, live-fire training. Although a standard for live-fire training exists, little physical data have been collected from the thermal environment encountered in this type of training. Acquiring data from live-fire training scenarios would be extremely beneficial to the fire service; it would allow for the evaluation and improvement of live-fire training evolutions as well as testing standards for firefighter personal protective equipment (PPE). In order to gather data from a firefighters immediate thermal environment in a live-fire training exercise, a portable heat flux and gas temperature measurement system was created and integrated into firefighter PPE. The system was tested and calibrated in a laboratory setting at the National Institute of Standards and Technology and then used to measure the ambient temperature and incident heat flux of a firefighters immediate environment in live-fire scenarios. Data were collected from 28 live-fire training evolutions conducted during seven different training scenarios. It was discovered that a mild thermal environment generally contained temperatures between 50C and 75C and heat fluxes around 1 kW/m2, while a severe thermal environment generally contained temperatures between 150C and 225C and heat fluxes between 3 kW/m2 and 6 kW/m2. Additionally, heat flux proved to be a more effective metric than temperature in evaluating the severity of the thermal environment. The portable thermal measurement system has provided new insights into conditions experienced by firefighters, which will greatly improve the safety and health of the US fire service.Ope
