ADAPTATIONS TO OZONE IN REFERENCE TO MUCOCILIARY CLEARANCE

Adaptation to [the air pollutant] O3 in respiratory tract mucociliary clearance was investigated. Rats (80) inhaled insoluble radioactively labeled particles to permit monitoring of clearance. The respiratory tract and the feces were counted for radioactivity at fixed intervals to determine clearance rates. A brief challenge to 1.2 ppm of O3 following particle deposition caused a substantial delay in rapid (mucociliary) clearance. This delay (or O3 effect) was eliminated by brief pre-exposure to 0.8 ppm of O3 3, days prior to deposition of particles. When a 13-day period intervened between the O3 pre-exposure and challenge, a substantial delay (or O3 effect) was seen again. The pre-exposure to O3 appeared to afford essentially complete protection at 3 days and no protection by 13 days.