Assessment of Thermal Discomfort when Wearing Bicycle Helmets – A Modelling Framework

Excessive sweating is a major ergonomic concern in bicycle helmet use and low wearing rates are suspected to originate, at least partly, from impaired thermal comfort due to accumulated sweat increasing skin wettedness at the head region. As a development from COST Action TU1101 WG4, we introduce a modelling framework for assessing the thermal comfort of bicy-cle helmet use. We predicted local sweat rate (LSR) at the head region as ratio to gross sweat rate (GSR) of the whole body and also based on sudomotor sensitivity (SUD), which relates the change in LSR to the change in body core temperature (ΔTre). We coupled those local models with models of thermoregulation predicting ΔTre and GSR, thus modelling head sweating in re-sponse to the characteristics of the thermal environment, clothing, level of activity, and expo-sure duration. We then validated the predictions of several local models (SUD, LSR/GSR) com-bined with different whole-body models against head sweat rates measured in the laboratory. Eventually, we developed thermal comfort criteria from head LSR by relating skin wettedness to the thermal properties of bicycle helmets. We discuss the potential of this approach as well as needs for further research.