AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Linking Different Exposure Patterns to Internal Lung Dose for Heterogeneous Ambient Aerosols
CHONG KIM, Jung-il Choi, USEPA
Abstract Number: 546 Working Group: Health Related Aerosols
Abstract Particulate matter (PM) in the ambient air is a complex mixture of particles with different sizes and chemical compositions. Because potential health effects are different for different size particles, specific dose of each size and their combination under realistic exposure conditions would be of interest in health risk assessment. In the present study we investigated deposition characteristics of typical bi-modal distribution aerosols under three different inhalation conditions: resting, mild exercise and moderate exercise. Oro-nasal breathing was used for exercise. The bimodal aerosols are composed of two uni-modal distributions having the mass median diameter of 0.3 um and 5 um with GSD of 1.8 and 2.0, respectively. Mass ratios (MR) between the two distributions were varied to simulate various types of aerosols. Total and compartmental lung deposition (TB and AL) were obtained for three size fractions, Ultrafine (PM0.1), Fine (PM0.1-2.5) and Coarse (PM2.5-10), by dynamic transport mathematical model. Results show that for mass deposition, both F and C deposit together in TB and AL with their absolute doses being approximately following MR. During exercise, deposition increases particularly in TB but shows a slight decrease in AL for C while Fine decreases in both TB and AL. UF’s contribution was minimal. For surface area, F and UF deposit at a ratio of 8:2 in both TB and AL. C can contribute substantially only in TB during exercise at MR< 0.5. For number deposition, both UF and F deposit together in both TB and AL at a ratio of approximately 6:4 regardless of exposure conditions. Absolue doses were higher at rest vs. exercise. Contribution of C was negligible. In conclusion, for typical bimodal aerosols UF, F and C deposit together at the same site with varying proportions. Their interactions may be a factor for altering heath risk outcome for multipollutant mixtures.