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Evaluating the Impact of Key Parameters on Evaporation of E-cigarette Aerosols

Institution: University of California, Los Angeles
Investigator(s): Liqiao (Vicky) Li,
Award Cycle: 2019 (Cycle 30) Grant #: T30DT1007 Award: $133,674
Subject Area: Environmental Exposure/Toxicology
Award Type: Dissertation Awards

Initial Award Abstract
The unique volatile property of e-cigarette (e-cig) emitted particles might affect the exposure to e-cig aerosols (ECAs) of both mainstream and secondhand vaping (SHV) that are distinctively different from tobacco smoke. The objective of the proposed study is to identify important parameters that affect the evaporation rates of both mainstream and simulated exhaled ECAs. With a rapid growth in the consumption of e-cig among adults and youth in the United States, there is still a lack of knowledge about the exposure and health effects of e-cigs. Unlike tobacco smoke generated by combustion, e-cigs utilize vaporization of the liquid mixture (so-called, e-liquid) to generate aerosols. Thus, the ECAs could be volatile due to the vaporization of propylene glycol with relatively high vapor pressure (i.e., 20 Pa) after heated. The volatile nature of e-cig aerosols would likely affect the exposure mechanisms and health outcomes associated with ECAs. While many existing studies have linked the property of evaporation to aerodynamic behaviors of ECAs, there has been no systematic study that determines to what extent the ECA evaporates with both intrinsic and extrinsic factors. Previous studies have demonstrated the impacts of SHV on indoor air quality, where high volatility has also been observed. However, there is limited information about how the volatility of SHV emissions can be affected. To fill these knowledge gaps, the overarching goal of this project is to identify key parameters (i.e., e-liquid components, and environmental conditions) that affect the evaporation rates of mainstream and mimic exhaled ECAs, respectively. To determine the evaporation rate of ECAs, the real-time measurements of ultrafine particles (UFPs) and fine particulate matter (PM2.5) decays in ECAs as well as di-ethyl-hexyl sebacate (DEHS) aerosols with the least volatility will be conducted in a well-controlled stainless steel chamber. An artificial lung system will be developed to mimic exhaled ECAs, simulating the human respiratory system. This proposed project will provide mechanistic data to better assess the impact of the e-cigs consumption on indoor air quality and potentially provide physical insight into the mainstream ECA exposure for the respiratory system.