The Chemical Transformation and Related Cytotoxicity of Vaping Emissions under the Indoor Atmospheric Aging Process

LINHUI TIAN, Wonsik Woo, Ying-Hsuan Lin, University of California, Riverside

     Abstract Number: 72
     Working Group: Indoor Aerosols

Abstract
E-cigarette emissions, containing various harmful substances, significantly contribute to indoor air pollution and raise concerns about secondary exposure to vaping byproducts. The chemical transformation of e-cigarettes during the vaping process is known to generate new compounds in both the gas and particle phases. While the chemical composition of fresh vaping emissions is well-characterized, the chemical aging products generated by ambient oxidants in the indoor environment are yet to be elucidated. The common flavors in e-liquid are terpenes, which are actively reacted with indoor O3 to chemically age e-cigarette aerosols and produce new oxidation products. In this work, e-liquid mixtures composed of propylene glycol (PG), vegetable glycerin (VG), and terpenes were injected into a 2 m3 FEP chamber. For the aging process of e-cigarette aerosols, 100 ppb O3 was introduced into the chamber, and the reaction lasted for one hour. After aging, more oxidized species, including various carbonyls, organic acids and possible organic peroxides, were observed in aged aerosols, mainly generated from the ozonolysis of terpenes and terpenoids. In addition, the aging process induced an increase in both particle concentration and particle size, as well as their lifetime in the atmosphere of fine particles. Furthermore, we observed that the aged e-cigarette aerosols with a higher degree of oxygenation and a higher potential for particle generation in both concentration and size resulted in greater cytotoxicity through both the lactate dehydrogenase (LDH) cytotoxicity assay and XTT assay. This work highlights the indirect danger of vaping in indoor environments with high ambient oxidant levels and provides a perspective that characterizes second-hand vaping exposure as a significant health risk.