Deposition of monodisperse particles in hollow models representing adult and child-size tracheobronchial airways.
A series of experiments was performed to determine deposition efficiencies of four sizes of radiolabeled monodisperse particles in custom-made hollow tracheobronchial models. The particles had geometric diameters of about 1, 5, 10, and 15 microm. The tracheobronchial models, consisting of a trachea and two or more additional generations, had dimensions representative of a typical adult, a 7-y-old child, and a 4-y-old child; the child-size models were appropriately scaled-down replicas of the adult-size model. Each deposition experiment was conducted using a steady inspiratory airflow representative of low physical activity for the appropriate age of individual: 20 L min(-1) for the adult; 9 L min(-1) for the 7-y-old; 5.5 L min(-1) for the 4-y-old. The results indicate that deposition efficiency of the particles increased substantially (up to 35 times) in all three models as particle diameter increased from 1-15 microm, undoubtedly as a result of particle impaction and sedimentation-related phenomena. An analysis of variance demonstrated the occurrence of statistically-significant (p < 0.05) main effects of hollow model size and particle size; the interaction between the two parameters was also significant. In general, deposition efficiencies of the various sizes of particles were greater in the child-size models than in the adult-size model; this effect may have risk assessment implications. In addition, the results obtained experimentally agreed more closely with those predicted using a radiation-protection mathematical particle deposition formulation as the particle size increased for each of the sizes of models.
Oldham
M J
MJ
Department of Community and Environmental Medicine, FRF, University of California, Irvine 92697-1825, USA.
Mannix
R C
RC
Phalen
R F
RF
D000328:Adult; D000336:Aerosols; D000367:Age Factors; D000396:Air Pollutants, Radioactive / Q000008:administration & dosage* / Q000009:adverse effects*; D001703:Biophysics / Q000295:instrumentation; D001980:Bronchi / Q000033:anatomy & histology* / Q000528:radiation effects*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D008433:Mathematics; D008953:Models, Anatomic; D008954:Models, Biological; D010316:Particle Size; D011835:Radiation Protection; D014132:Trachea / Q000033:anatomy & histology* / Q000528:radiation effects*
D000336:Aerosols; D000396:Air Pollutants, Radioactive