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Effects of Device Type, Liquid Composition, and Emission Level on Characteristics of Aerosol Generated from Tank-Style E-cigarettes and JUUL Pods
YUENING GUO, Liqiao Li, Yi Luo, Yifang Zhu, University of California, Los Angeles
Abstract Number: 261
Working Group: Aerosol Exposure
Abstract
E-cigarettes are increasingly popular among adolescents in recent years. Tank devices and JUUL pods are the newest and most widely-used e-cigarette devices. However, there are substantial differences between their device structures and e-liquid compositions. The characteristics of aerosols generated from these two devices warrant better understanding and cross-comparisons for future human exposure studies and policy making. This work compared the relative effect of device type (Vapor-fi Volt II tank device vs. JUUL pods), type of nicotine used in e-liquids (freebase nicotine vs. nicotine benzoate salt), and emission level (i.e., one and three 4-second puffs) on the characteristics of mainstream e-cigarette aerosols. The e-cigarette aerosol was introduced into a 460-L mixing chamber and then measured for particle number concentration (PNC), PM2.5 mass concentration, size distribution, and evaporative properties (i.e., particle lifetime and volatility). The results suggested similar PNC level between tank and JUUL devices. Nevertheless, JUUL generated more than twice of ultrafine particles (da < 0.1 μm) than tank devices. PM2.5 in tank aerosols were more than two times higher than JUUL aerosols. Bimodal size distribution was observed in all samples, with the first mode at 0.06-0.09 μm, and second mode at 0.27-0.31 μm. The change of nicotine type shifted the first mode of size distribution. Device type was a significant indicator for PM2.5 (p < 0.05) but not for PNC. Nicotine type was only a significant indicator for PNC in 1-puff samples, and it had almost no effect on PM2.5. Aerosols generated from tank devices were significantly less volatile than JUUL (p < 0.05), while volatility for the two nicotine types has no significant difference. Switching device brought more dramatic effects to aerosol characteristics than switching nicotine source in e-liquids. Future studies on e-cigarette exposures are suggested to treat tank devices and JUUL pods as two distinct emission sources.