title: Effect of body size on breathing pattern and fine-particle deposition in children.
abstract: Interchild variability in breathing patterns may contribute to variability in fine particle lung deposition and morbidity in children associated with those particles. Fractional deposition (DF) of fine particles (2-microm monodisperse, carnauba wax particles) was measured in healthy children, age 6-13 yr (n = 36), while they followed a resting breathing pattern previously determined by respiratory inductance plethysmography. Interchild variation in DF, measured by photometry at the mouth, was most strongly predicted by their tidal volume (Vt) (r =0.79, P < 0.001). Multiple regression analysis further showed that, for any given height and age, Vt increased with increasing body mass index (BMI) (P < 0.001). The overweight children (> or =95th percentile BMI) (n = 8) had twice the DF of those in the lowest BMI quartile (<25th percentile) (n = 9; 0.28 +/- 0.13 vs. 0.15 +/- 0.06, respectively; P < 0.02). In the same groups, resting minute ventilation was also significantly higher in the overweight children (8.5 +/- 2.2 vs. 5.9 +/- 1.1 l/min; P < 0.01). Consequently, the rate of deposition (i.e., particles depositing/time) in the overweight children was 2.8 times that of the leanest children (P < 0.02). Among all children, the rate of deposition was significantly correlated with BMI (r = 0.46, P = 0.004). These results suggest that increased weight in children may be associated with increased risk from inhalation of pollutant particles in ambient air.
authors.affiliation: Center for Environmental Medicine, Asthma and Lung Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA. william_bennett@med.unc.edu
authors.forename: William D
authors.initials: WD
authors.lastname: Bennett
authors.forename: Kirby L
authors.initials: KL
authors.lastname: Zeman
mesh_terms: D000293:Adolescent; D000336:Aerosols / Q000493:pharmacokinetics*; D000393:Air Pollutants / Q000493:pharmacokinetics*; D049628:Body Size / Q000502:physiology*; D002648:Child; D005260:Female; D006801:Humans; D019570:Inhalation Exposure; D008168:Lung / Q000502:physiology*; D008297:Male; D010316:Particle Size; D012119:Respiration; D013223:Statistics as Topic
chemical_list: D000336:Aerosols; D000393:Air Pollutants