Seven adult male healthy volunteer subjects were exposed to 0.15 ppm each of O3, SO2 and NO2 alone and in combination, with intermittent light exercise for two hours. Three of the 7 subjects developed cough during deep inspiration and one subject had chest pain during exposure to O3 alone. Among the various indices of pulmonary function tests, specific airway conductane (Gaw/Vtg) was the most sensitive index to examine the changes produced by the exposure to O3 and other pollutants. Significant decrease of Gaw/Vtg in comparison with control measurements was observed in 6 of 7 subjects during exposure to O3 alone, and in all subjects during exposures to the mixture of O3 and other pollutants. However, no significant enhancement of effect was observed in the mixture of O3 and other pollutants, although a slightly greater decrease of Gaw/Vtg was observed for the mixture of O3 and other pollutants than for O3 alone.