Deposition Simulator for Tobacco Aerosol in the Human Respiratory System

AKINA MORI, Shigeaki Ito, Takashi Sekine, Japan Tobacco Inc.

     Abstract Number: 564
     Working Group: Health-Related Aerosols

Abstract
The assessment of the health impact of tobacco aerosol requires an understanding of the aerosol behavior and deposition amount in the human respiratory tract. Computer fluid dynamics (CFD) modeling has generally been adopted to predict such information. However, the CFD modeling of tobacco aerosol has a high calculation cost and is not conducted for the whole airway system owing to the complex nature of tobacco aerosol and the respiratory system. To assess a number of chemical constituents and mixtures in the overall respiratory system, we modified the existing multiple-path particle dosimetry (MPPD) model, which is a non-CFD deposition simulator of aerosol. Our new version of the MPPD model accounts for the mixing of the puff in the oral cavity and deep lung and the air–tissue interaction of constituents in the gas phase. Considering the aerosol properties, constituents’ physicochemical properties, and user topography, the model estimates the change in the droplet diameter through the respiratory tract and the deposition fraction of chemical constituents of interest in one puff of a tobacco product, such as a conventional cigarette or electronic nicotine delivery system. Sensitivity analysis reveals that known important parameters (e.g., the vapor pressure, particle diameter, and activity coefficient) work properly in our model, and the changes in the aerosol deposition due to changes in the parameters are consistent with previous knowledge. Importantly, the prediction was carried out within 3 minutes even with 10 constituents, demonstrating the successful reduction of the calculation cost and time. The new version of the MPPD model is thus a time-saving and effective tool with which to estimate the multi-constituent aerosol especially for tobacco products.