Experiments were carried out to determine whether water content-induced airway resistance increase could be potentiated by facial cold or increased by subsequent exposure to increased inspired water content. The result showed: (a) the product airway resistance times intrathoracic gas volume at functional residual capacity (Raw × Vtg) increase with increased inspired water content; (b) the increase in Raw × Vtg was greater on the second exposure to a water content of 16g/m3 (31 °C, 50% relative humidity); (c) superimposition of facial cold application while inhaling air with a water content of 16 g/m3 led to a further increase in Raw × Vtg, and (d) it is suggested that increased inspired water content increases the responsiveness of the tracheobronchial