(288d) Computational Modeling of Ozone Dose Distribution in the Respiratory Tract

The pattern of lung injury induced by inhalation of ozone is believed to depend on the local dose delivered to different tissues in the respiratory tract. To examine the effect of the upper airways on the local dose distribution, we perform numerical simulations of ozone transport and uptake in an anatomically-accurate geometrical model of the respiratory tract of a Rhesus monkey. The model geometry was created using three-dimensional reconstruction of MRI images of the respiratory tract, including the nasal passages, the larynx, and the first thirteen generations of the tracheobronchial tree. Using a quasi-steady diffusion-reaction model for the interaction between O3 and endogenous substrates in the respiratory tract lining fluid, three-dimensional distributions of O3 concentration were obtained through numerical solution of the conservation equations for steady inspiratory and expiratory flows at physiologically relevant Reynolds numbers. The total rate of ozone uptake within each section of the respiratory tract was determined, and hot spots of ozone flux on the walls were identified. The simulation results show that the structure of the upper airways have a significant effect on the distribution of ozone flux on the airway walls, by producing additional hot spots of ozone flux upstream of the trachea at the nasal atrium, middle turbinates, inferior meatus, laryngopharynx and rima glottides. In addition, the presence of the larynx leads to a more uniform wall flux distribution within the trachea, compared to the corresponding simulations in the same airway structure without the larynx.