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Assessing E-cigarette Aerosol Physical and Chemical Changes Post-emission Using an Idealized Physical Throat Model
KAITLYN SUSKI, Zarina Munshi, Raj Rao, Brad Ingebrethsen, Bryan Toth, Won Choi, Hosna Mogaddedi, JUUL Labs
Abstract Number: 596
Working Group: Health-Related Aerosols
Abstract
E-cigarette aerosol is composed of only a few chemical compounds. Nevertheless, it is a complex system that undergoes rapid and constant chemical and physical change once emitted from devices due to its hygroscopic nature and range of component volatilities. During inhalation, volatile aerosol components deposit by a combination of vapor and particle deposition and the extent to which these deposition modes occur depends on particle size and number concentration as well as the vapor pressures of the volatile components in the aerosol. The vapor pressure of nicotine from e-liquids and how it changes based on e-liquid composition is not well characterized. This work aims to link changes in aerosol chemistry as e-cigarette particles travel through the respiratory tract to the vapor pressures of those components by measuring deposition rates in an idealized model airway.
The experiments presented here estimate deposition of e-liquid constituents using a humidified tube (RH ≈ 100%, 40 °C) with the same internal volume as the oropharyngeal region of the respiratory tract in an average adult male. E-cigarette aerosols were drawn through this model airway using a simulated human puff and inhalation flow sequence. Aerosol was collected and characterized ex-device and ex-airway via light scattering, gravimetric weighing, and gas and liquid chromatography. The light scattering and gravimetric results indicate rapid e-cigarette aerosol growth in the airway model due to water uptake. Additionally, there was greater removal of the more volatile components compared to lower volatility components based on the chromatography data. These results show that idealized model airways provide a relatively simple and low-cost approach to assess e-cigarette aerosol transport in human airways. While these experiments are limited to a physical model of the oropharyngeal region, similar water uptake kinetics and volatile component deposition processes would be expected to take place in more complex ways throughout the respiratory system, which will be explored by combining these results with modeling.