An electronic cigarette (e-cig) generates aerosols by vaporizing the e-liquid, which mainly consists of propylene glycol (PG), vegetable glycerin (VG), and nicotine. Understanding the effects of e-liquid main compositions on e-cig aerosols is important for exposure assessment. This study investigated how the PG/VG ratio and nicotine content affect e-cig aerosol emissions and dynamics. A tank-based e-cig device with 10 different flavorless e-liquid mixtures (e.g., PG/VG ratios of 0/100, 10/90, 30/70, 50/50, and 100/0 with 0.0% or 2.4% nicotine) was used to puff aerosols into a 0.46 m³ stainless steel chamber for 0.5 h. Real-time measurements of particle number concentration (PNC), fine particulate matter (PM_2.5), and particle size distributions were conducted continuously throughout the puffing and the following 2-h decay period. During the decay period, particle loss rates were determined by a first-order log-linear regression and used to calculate the emission factor. The addition of nicotine in the e-liquid significantly decreased the particle number emission factor by 33%. The PM_2.5 emission factor significantly decreased with greater PG content in the e-liquid. For nicotine-free e-liquids, increasing the PG/VG ratio resulted in increased particle loss rates measured by PNC and PM_2.5. This pattern was not observed with nicotine in the e-liquids. The particle loss rates, however, were significantly different with and without nicotine especially when the PG/VG ratios were greater than 30/70. Compared with nonvolatile di-ethyl-hexyl subacute (DEHS) aerosols, e-cig particle concentration decayed faster inside the chamber, presumably due to evaporation. These results have potential implications for assessing human exposure to e-cig aerosols.

Copyright © 2020 American Association for Aerosol Research

电子烟（e-cig）通过蒸发电子液体产生气溶胶，该电子液体主要由丙二醇（PG），植物甘油（VG）和尼古丁组成。了解电子液体主要成分对电子烟气溶胶的影响对于暴露评估很重要。这项研究调查了PG / VG比例和尼古丁含量如何影响e-cig气溶胶的排放和动力学。基于罐的电子烟设备，具有10种不同的无味电子液体混合物（例如PG / VG比率为0 / 100、10 / 90、30 / 70、50 / 50和100/0，分别为0.0％或2.4％尼古丁）用于将气雾剂喷入0.46 m ³不锈钢室中0.5小时。实时测量颗粒数浓度（PNC），细颗粒物（PM _2.5），并且在整个膨化过程中以及随后的2小时衰减时间内连续进行粒度分布。在衰减期间，通过一阶对数线性回归确定颗粒损失率，并将其用于计算排放因子。在电子液体中添加尼古丁可将颗粒数排放因子显着降低33％。随着电子液体中PG含量的增加，PM _2.5排放因子显着降低。对于不含尼古丁的电子液体，提高PG / VG比例会导致PNC和PM _2.5测得的颗粒损失率增加。在电子液体中，尼古丁没有观察到这种模式。然而，有和没有尼古丁的情况下，颗粒损失率有显着差异，尤其是当PG / VG比大于30/70时。与不挥发的二乙基己基亚急性（DEHS）气溶胶相比，电子烟颗粒浓度在室内的衰减更快，可能是由于蒸发造成的。这些结果对于评估人类对电子烟气溶胶的暴露具有潜在的影响。

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