Mucociliary clearance from the lungs of rabbits following single and intermittent exposures to ozone

This study examined the effects of ozone (O3) inhalation on mucociliary clearance from the tracheobronchial tree. Rabbits were exposed for 2 h at 0.1, 0.25, and 0.6 ppm or for 2 h/d for 14 consecutive days at 0.25 and 0.6 ppm. Clearance was assessed by measuring the retention of radioactivity tagged, inert tracer particles inhaled immediately after the single 2-h exposure, or 24 h after 2, 7, or 14 of the daily exposures. Single exposures resulted in a concentration-related trend toward retarded particle clearance, with a statistically significant difference occurring after exposure to 0.6 ppm. Intermittent exposures produced no significant change in clearance rate, although there was a suggestion of retarded clearance at early time points at both 0.25 and 0.6 ppm.