Nasal Contribution to Breathing and Fine Particle Deposition in Children Versus Adults

Both the route of breathing, nasal versus oral, and the effectiveness of the nose to filter inhaled, fine particles may differ between children and adults. This study compared (1) the nasal contribution to breathing at rest and during mild to moderate exercise in children (age 6–10 yr) versus young adults and (2) the nasal deposition efficiency (NDE) of fine particles (1 and 2 μm MMAD, GSD < 1.2) under resting and light exercise breathing conditions in the same children and adults. Nasal contribution to breathing was assessed by respiratory inductance plethysmography and a nasal mask with flow meter during incremental exercise on a bicycle ergometer. Fine particle deposition fractions for nasal and oral breathing were assessed by inhalation of monodisperse carnauba wax particles and laser photometry to determine inhaled/exhaled concentrations. There was a trend for children to have a lesser nasal contribution to breathing at rest and during exercise, but the differences from adults were not statistically ...