AIRWAY RESPONSE TO SHORT-TERM INHALATION OF NO2, O3 AND THEIR MIXTURE IN HEALTHY MEN

One hour inhalation of 0.7 ppm (1.32 mg/m3) of nitrogen dioxide (NO2), 0.7 ppm (1.4 mg/m3) of ozone (O3), and their mixture, 0.5 ppm (0.9 mg/m3) of NO2 and 0.5 ppm (1.0 mg/m3) of O3, and sham inhalation were conducted in five healthy male volunteers through mouth breathing using a multipurpose inhalation apparatus. Airway response was measured by specific airway conductance (Gaw/Vtg) and maximum expiratory flow rate at 50 and 25 percent forced vital capacity (Vmax50, Vmax25). Evaluations by analysis of variance revealed: no significant effect in inhalation of NO2 alone, slight significant transient decrease of Vmax50 in inhalation of O3 alone (0.1>p>0.05), and slight reversible decrease of Gaw/Vtg and Vmax50 in halation of NO2 and O3 combination (0.1>p>0.05). As their variations were within the range of normal diurnal change, these results were considered to be non-adverse effects.