An experimental study was conducted to evaluate changes in pulmonary reactivity resulting from repeated vanadium pentoxide (V2O5) dust inhalation. The study assessed pulmonary reactivity to V2O5 through the use of provocation challenges, and compared V2O5 reactivity before and after subchronic V2O5 exposure. A total of 24 adult, male cynomolgus monkeys (Macaca fascicularis) were exposed by inhalation for 6 h per day, 5 days per week, for 26 weeks. Two V2O5-exposed groups (n = 8 each) received equal weekly V2O5 exposures (concentration x time) with different exposure profiles. One V2O5-exposed group received 0.1 mg V2O5 m-3 on Mondays, Wednesday and Fridays, with a twice-weekly peak exposure of 1.1 mg V2O5 m-3 on Tuesdays and Thursdays, and was included to investigate the influence of an exposure regimen with peaks on the development of pulmonary hyper-reactivity. The other V2O5-exposed group received a constant daily concentration of 0.5 mg V2O5 m-3. A control group (n = 8) received filtered, conditioned air. Pre-exposure challenges with V2O5 produced a concentration-dependent impairment in pulmonary function, characterized by airway obstructive changes (increased resistance and decreased flow). Analysis of respiratory cells recovered from the lung by bronchoalveolar lavage demonstrated that airway obstruction was accompanied by a significant influx of inflammatory cells into the lung. Subchronic V2O5 inhalation did not produce an increase in V2O5 reactivity in comparison to the control group, and cytological, immunological and skin test results indicate the absence of allergic sensitization. Instead, a trend toward decreased pulmonary reactivity was found following subchronic V2O5 inhalation.(ABSTRACT TRUNCATED AT 250 WORDS)