The effects of firefighting boots and personal protective equipment load on foot thermal comfort

Maintaining foot comfort is important as it influences the overall comfort of the human body. Shoe microclimate and foot skin temperature have been suggested to contribute to the thermal sensation of the foot. Considering the thermal environment and personal protective equipment (PPE) used for structural and proximity firefighting, climatic chamber tests with 13 male participants were conducted during standing and walking. Four test conditions – unloaded with training shoes, loaded with training shoes, unloaded with firefighting boots, and loaded with firefighting boots – were designed to investigate the effects of firefighting boots and PPE load on the thermal comfort of the human foot. Physiological variables of in-shoe and foot skin temperature at the whole and local regions of the foot were measured and subjective responses were gathered using psychological scales. The results showed that wearing firefighting boots may elevate the thermal sensation of wearers. The PPE load increased the in-shoe and foot skin temperature as well as subjective ratings. Subjective sensations of the foot were strongly correlated with in-shoe and skin temperature in the plantar regions. Correlation analysis of thermal sensation at the whole and local foot regions indicated that the sensation at the forefoot was closest to the whole foot, followed by the midfoot and heel. The findings address the relationship of physiological and subjective variables as well as the thermal sensation of whole and local foot regions, which can be considered for footwear design and thermal comfort prediction of the foot and whole body.