Thermo-physiological impact of different firefighting protective clothing ensembles in a hot environment

It is currently unclear how the assembly of different fabric layers of personal protective clothing (PPC) contributes to differences in thermal comfort among garments. Therefore, we used two different approaches to investigate the effect of PPC on body heat dissipation: a technical characterization of textiles (using sweating Torso methodology) and thermo-physiological wearing trials. We hypothesized that the technical characterization provides a similar outcome compared to the wearing trials and, thus, proves to have high thermo-physiological relevance. Thirteen different PPC were investigated using the sweating Torso methodology. Three out of these thirteen were then selected for inclusion in a series of human subject trials in a hot environment. Results from human trials and Torso testing were related to each other. The thermal and evaporative properties of the selected PPC typically differed and effects were observed for the thermo-physiological responses of human study participants. Differences in Torso surface temperature of up to 9℃ and moisture accumulation in the protective clothing systems of up to 184 g·m–2 were detected using the sweating Torso methodology. Moderate intensity exercise with the human study participants induced textile-dependent differences of up to 0.9 ± 0.2℃ (P < 0.001) and 1.2 ± 0.2℃ (P = 0.008) for excessive core body and excessive skin temperature, respectively. Using the sweating Torso methodology, physiologically relevant differences in textile performance could be detected among different PPC. Consequently, sweating Torso is a relevant tool to gain insight into human thermo-physiological responses to different PPC with similar end-use based on their dry and wet heat transfer characteristics.