Previous studies suggest that lung function tests using monodisperse aerosols can help to identify early stages of lung diseases. We investigated intrapulmonary particle loss and aerosol bolus dispersion-a marker of convective gas transport-in 32 women with asymptomatic nonspecific bronchial hyperresponsiveness (BHR) compared with 60 women without BHR. Deposition of inhaled particles (0.9 micrometer mass median aerodynamic diameter [MMAD]) was calculated from particle losses of inhaled aerosol boluses consisting of di-2-ethylhexyl sebacate droplets. Convective gas mixing was assessed by the aerosol bolus dispersion method. Women with BHR, nonsmokers as well as smokers, showed significantly increased deposition of aerosol particles (nonsmokers: 45.6 +/- 8.8%; smokers: 49.2 +/- 5.4%; mean +/- SD) compared with the control group of female nonsmokers without BHR (38.2 +/- 9.1%; mean +/- SD) (p < 0.01). Aerosol bolus dispersion values showed a trend for higher values in subjects with BHR (nonsmokers: 572 +/- 122 cm3; smokers: 587 +/- 85 cm3) compared with the control group (542 +/- 88 cm3) (p = 0.2). Also, the maximal expiratory flow at 25% vital capacity (MEF25) showed a trend for decreased values in nonsmokers with BHR compared with nonsmokers without BHR (64 +/- 16% of predicted versus 78 +/- 24% of predicted; p = 0.03). These results suggest that deposition of inhaled particles (0.9 micrometer MMAD) administered by the aerosol bolus technique is a sensitive index of peripheral lung injury that is usually not assessable by conventional methods.