Particle deposition in the guinea pig respiratory tract

Abstract

Equations relating particle size of aerosols to deposition by impaction, diffusion and sedimentation are applied to a previously established model of the guinea pig lung using a tidal volume of 4.44 cm 3 and a respiratory rate of 60 breath min −1. These calculated deposition values are combined with measured values of nasal deposition to give an estimate of the particle deposition characteristics of the guinea pig respiratory tract. The nasopharyngeal-tracheobronchial (NP-TB) region removes 99% of unit density spherical particle 10 μm or more in diameter. Deposition in this region reaches a minimum of 10% at a particle diameter of 0.8 μm. For particles less than 0.8 μm, deposition increases because of diffusion. Deposition in the pulmonary region is about 17% for particle diameters from 0.08 to 4 μm. For typical polydisperse aerosols with mass median diameters above 1 μm, a greater fraction of the mass than of the count is deposited in the NP-TB region, while a smaller fraction of the mass than of the count is deposited in the pulmonary region. Aerosol clouds with mass median diameters less than 0.1 μm deposit a greater fraction of the count than of the mass in the NP-TB region and a smaller fraction of the count than of the mass in the pulmonary region.