Regional deposition and clearance of particles in the human nose

Abstract

The sites of particle deposition and clearance rates in the human nose have been investigated for inhaled monodisperse particles in the size range 2–10 μm. At least 45 per cent of the retained material was deposited in the anterior region of the nasal passages and the site of maximum deposition was 2–3 cm behind the tip of the nose. Although clearance of particles from this region was very variable, a long-term retention with a biological half-life greater than 3 hr was always observed. In approximately half the experiments, the site of maximum deposition in the nose was in the region of the junction between the ciliated and nonciliated epithelia: particles deposited on the ciliated epithelium were rapidly removed by the mucociliary clearance mechanism, while particles deposited in the unciliated region were removed relatively slowly. In some cases, as much as 60 per cent of the particles initially deposited in the anterior region were removed with half-lives of less than 20 min.