Assessment of regional deposition of inhaled particles in human
lungs by serial bolus delivery method.
Kim, Chong S., S. C. Hu, P. Dewitt, and T. R. Gerrity.
Human Studies Division,National Health and Environmental Effects
Research Laboratory U.S. Environmental Protection Agency, Research
Triangle Park, NC 27711 and Center for Environmental Medicine and
Lung Biology, University of North Carolina, Chapel Hill, NC 27599
APStracts 3:0342A, 1996.
Detailed regional deposition of inhaled particles was investigated in
young adults (N=11) using a serial bolus aerosol delivery technique.
A small bolus (45 ml half width) of monodisperse aerosols (Dp =1, 3
and 5 [mu]m dia.) was delivered sequentially to a specific volumetric
depth of the lung (Vp=100-500 ml with a 50 ml increment), while the
subject inhaled clean air via a laser aerosol photometer (25 ml dead
volume) with a constant flow rate (Q=150, 250 and 500 ml/s) and
exhaled with the same flow rate without a pause to the residual
volume. Deposition efficiency (LDE) and deposition fraction (LDF) in
ten local volumetric regions as well as total deposition fraction
(TDF) of the lung were obtained. LDE was found to increase
monotonically with increasing lung depth for all three Dps used. LDE
was greater with smaller Q values in all lung regions. Deposition was
distributed fairly evenly throughout the lung regions with a tendency
for an enhancement in the distal lung regions for Dp = 1 [mu]m.
Deposition distribution was highly uneven for Dp = 3 and 5 [mu]m and
the region of the peak deposition shifted toward the proximal regions
with increasing Dp. Surface dose was 1 - 5 times greater in the small
airway regions and 2 - 17 times greater in the large airway regions
compared with the alveolar regions. The results suggest that local or
regional enhancement of deposition occurs in healthy subjects and
that the local enhancement can be an important factor in health risk
assessment of inhaled particles.
Received 3 November 1995; accepted in final form 18 June 1996.
APS Manuscript Number A1161-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996