Effects of draught on thermal comfort and respiratory immunity

Draught has been observed to have an effect on human thermal comfort and induce upper respiratory tract infections (URTI), which indicates that it may reduce immunity against respiratory diseases. This study aims to explore the relationship between thermal comfort and respiratory immunity in an air-conditioned environment. Eleven tests were conducted using supply air temperature of 24 °C and supply air velocity of 1 m/s in an environmental chamber. Secretory immunoglobulin A (SIgA) and lysozyme were selected as immune biomarkers, and subjective questionnaires concerning thermal sensation vote and thermal comfort vote (TSV and TCV), draught vote (DV), and air movement acceptability were collected after airflow intervention. The symptoms of URTI were also assessed. The results showed that the lysozyme concentration decreased significantly from 835.01 to 434.16 ng/ml after the tests were conducted (p < 0.01). Furthermore, the lysozyme concentration after the tests showed a significant positive correlation with TSV (Rs = 0.527, p < 0.05). The colder the subjects felt, the greater the decrease in the lysozyme change rate. There was no correlation between SIgA and TSV after the tests (p > 0.05). This study revealed that staying in comfortable conditions contributes to a high level of respiratory immunity.