Fig. 6 displays subjective response of irritations of nose, throat and eyes. Average votes of irritation of nose, throat and eyes were in the range of 0.21–0.68, 0.28–0.62 and 0.25–0.85, respectively. All of them were in the range of No (0) and slight irritation (1). Correlations of SBS with room air temperature and thermal gradient are shown in Table 7. The results showed that subjective response of the irritations was insignificantly affected by thermal gradient. Throat irritation was insignificantly related to room air temperature. On the contrary, irritations of nose and eyes decreased significantly with increase of room air temperature (p ¼ 0:046 and 0.001, respectively). One possible reason is that more moisture is in the air at higher room temperature and tropically acclimatized subjects are used to relatively high moisture content.