Abstract
One reason riders fail to wear a helmet properly in summer is the sense of discomfort when a helmet is worn. We investigated the major factors in head discomfort when a helmet is worn in the summer season. The experiments were conducted under two conditions : with and without wind.
Despite finding no significant difference in humidity inside the helmet with and without wind, and only a slight difference of 0.43-0.47°C in temperature, wind lessened head discomfort compared with the no-wind condition. The results of a cluster analysis showed that subjective symptoms in the head region and the level of carbon dioxide inside the helmet were in the same cluster, suggesting a close relationship between head discomfort and the level of carbon dioxide inside the helmet. In addition to the factors of heat and humidity that have been used as indicators of head discomfort, it appears that the carbon dioxide level, as an indicator for ventilation inside the helmet, can also be used.
