Comparing the improve effect of local cooling on worker’ thermal comfort, EEG, and salivary IgA concentration in hot environments

Fan cooling (FC) is widely used by factory workers when air-conditioning is unavailable, while wearable cooling garments (CG) offer a better choice in personal thermal management. In this study, the effect of FC and CG on thermal comfort, electroencephalography (EEG) signals, and respiratory immune function were compared in hot environments. Experiments were conducted in climate chamber involving twenty participants. Participants performed packing activity and experienced three experimental conditions including the WS (wearing working suits without any local cooling), FC, and CG condition. During the experiments, EEG, skin temperature, local skin heat flux, and salivary secretory immunoglobulin A (S-IgA) were measured. Subjective responses about thermal comfort, thermal sensation, perceived air quality were collected. Results revealed that the FC and CG conditions affected the mean EEG power and S-IgA-C (S-IgA concentration) significantly. Compared to the WS condition, the mean EEG power was reduced by 22.9 % and 44.5 % under the FC and CG conditions, respectively. Meanwhile, the dimensionless S-IgA-C was increased by 75.5 % and 131.9 %, respectively. In warm or neutral state, the S-IgA-C reached to the highest level, and the mean EEG power tended to be the lowest. The CG were more effective than the FC in improving thermal comfort, reducing mean EEG power, and enhancing S-IgA-C. By direct contact, CG increased temperature difference between the body and surrounding, and thus enhanced heat transfer from the body greatly. The fan improves convective and evaporative heat transfer coefficient, while this effect becomes limited in hot environments.