The Effect of Nasal Passage Characteristics on Particle Deposition

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Abstract
This study determined the effect of nostril dimensions, nasal passage geometry, and nasal resistance (R) on particle deposition efficiency (PDE) in 40 healthy, nonsmoking adults (24 male, 16 female) at a constant flow rate. An aerodynamic particle sizer measured the diameter and concentration of a polydispersed (1−10-μm diameter) aerosol drawn unidirectionally into the nose and out the mouth. For each particle size, the concentration of particles entering the nose (Cin) and leaving the mouth (Cout) was measured. Nasal PDE, defined as (Cin − Cout)/Cin*100, was calculated for bilateral and unilateral flow. A mixed, nonlinear model was used to fit the PDE to two models based on two sets of specifications. The geometric model included particle aerodynamic diameter (da), nostril dimensions, and minimum nasal cross-sectional area (Amin); the resistance model included particle da and R. Left and right nasal passage PDE significantly correlated for 2- to 6-μm diameter particle sizes. The results showed that in both bilateral and unilateral geometric models, particle da, Amin, and nostril length to width ratio (E) significantly affected the PDE. In the resistance model, particle da significantly affected both unilateral and bilateral PDE; however, R significantly affected only unilateral PDE. The results showed that both models can be used to predict the PDE; however, the nasal passage geometry information is easier to obtain than the resistance information.