Numerical assessment of ambient inhaled micron particle deposition in a human nasal cavity

Understanding the particle exposure characteristics in human respiratory airways plays important roles in assessing the therapeutic or toxic effects of inhaled particles. In this study, numerical modelling approach was used to investigate micron-sized particle deposition in an anatomically realistic human nasal cavity. Flow rate of 15 L/min representing typical normal breathing rate for an adult was adopted, and particles were passively released from the ambient air adjacent to the nostrils. Through introducing a surface mapping technique, the 3D nasal cavity was "unwrapped" into a 2D planar domain, which allows a complete visual coverage of the spatial particle deposition in the intricate nasal cavity. Furthermore, deposition enhancement factor was applied to extract regional deposition concentration intensity relative to background intensity of the whole nasal passage. Results show that micron particle exposure in the nasal cavity is closely associated with nasal anatomical shape, airflow dynamics, and particle inertia. Specifically, the main passage of the nasal cavity received high particle deposition dosage, especially for larger micron-sized particles due to increased particle inertia. The nasal vestibule exhibited limited particle filtration effect and most deposited particles in this region concentrated posteriorly.