AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
An Aerosol Sampler to Estimate Regional Deposition within the Human Respiratory Tract
KIRSTEN KOEHLER, John Volckens, Colorado State University
Abstract Number: 526 Working Group: Aerosol Exposure
Abstract This work describes the development of an aerosol sampler to mimic regional particle deposition in the human respiratory tract. The motivation for this research is to improve our ability to estimate inhaled aerosol dose. Current methods for aerosol measurement and exposure/risk assessment are based on particle aspiration (i.e., inhalable PM) or on penetration to various regions of the respiratory system (i.e., PM10). However, a large proportion of inhaled aerosol is subsequently exhaled and does not contribute to the dose. Furthermore, regional deposition can also drive the incidence of certain health outcomes (e.g., sinusitis vs. bronchitis vs. pneumonia). Therefore, the goal of this work was to develop an aerosol sampler capable of estimating particle deposition to three regions of the human respiratory tract. The International Commission on Radiological Protection (ICRP) has developed a model that estimates particle deposition, as a function of particle aerodynamic diameter, to three main regions: head airways, tracheobroncial, and alveolar. We developed a semi-empirical model to design substrates capable matching the ICRP-defined deposition to these regions. These substrates, made from polyurethane foam and mesh screen, have specific dimensions (i.e., length, diameter, fiber size) and operating conditions (e.g., face velocity) necessary to reproduce the aerodynamics of aerosol deposition in the human respiratory tract. The substrates are placed in series within a sample holder that operates at 16.7 liters per minute of flow. Performance of the sampler was evaluated using test aerosols ranging in size from 0.01 to 10 microns. These results show good agreement with the ICRP convention for regional lung deposition. Comparing two direct-reading PM10 mass samplers, one with regional deposition sampler placed upstream and the other as total PM10 reference, we evaluated the overestimation of lung deposition as a function of time for ambient aerosols. Substantial differences between PM10 intake and deposition were observed.