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

Abstract

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 significant. Children did, however, have significantly decreased NDE for 2-μm particles under light exercise breathing conditions compared to adults, suggesting less efficient nasal filtering for larger particles and higher flow conditions. These results suggest that the lungs of children may be exposed to higher concentrations of inhaled, ambient particles than adults.

Supported by U.S. EPA Cooperative Agreement 824915/ 829522.

This study was performed in laboratories of the U.S. Environmental Protection Agency. The views expressed in this article are those of the authors and do not not necessarily reflect the views or policies of the agency and no official endorsement should be inferred. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.