Abstract Vaping is promoted as a healthier alternative to smoking over the recent years, and e-cigarette (EC) users are considered to affect air quality (and thus contribute to passive smoking) much less than tobacco cigarette (TC) smokers. Here we test this hypothesis, by comparing measurements of the size distributions of particles and the levels of Volatile Organic Compounds (VOCs) exhaled by both EC and TC users. A total of 26 individuals (16 EC users and 10 TC users) provided exhaled air samples that were analyzed using the same protocol. Our measurements show that the particle number concentration emitted by both EC and TC users are comparable, but the size distributions of the particles emitted by the former exhibit significantly higher variability compared to those from the latter. The burden of the VOCs was much higher in the exhaled air of TC smokers compared to that of EC users. Although some of the VOCs measured in the exhaled air of EC users were expected, as they are used directly in the e-liquids, the collected mixtures were highly variable (i.e., varying significantly from case to case) with only 8 compounds being common among all individuals participating in the study. In contrast, we identified 65 compounds among the TC smokers that were common among the participants. Toxic compounds (e.g., benzene, acetaldehyde, toluene, xylenes, styrene, phenol, naphthalene, etc.) were also present in the exhaled air of EC users. The high variabilities observed in the size distributions of the exhaled particles and the levels of VOCs from different EC users (i.e., due to different devices, operational settings and liquids) warrants for further research in order to fully understand the main- and side-stream effects of EC use in the human micro-environment. Despite that, the high particle emissions and the presence, even at trace levels, of toxic VOCs in the exhaled air of EC users that are reported in this study, suggests that ECs should not be considered as harmless substitutes of TCs.

中文翻译：

---

电子烟和卷烟用户呼出的粒度分布和挥发性有机化合物的比较

摘要 近年来，电子烟被推广为一种更健康的吸烟替代品，并且电子烟 (EC) 用户被认为对空气质量的影响（从而导致被动吸烟）远小于烟草卷烟 (TC) 吸烟者。在这里，我们通过比较颗粒尺寸分布的测量值和 EC 和 TC 用户呼出的挥发性有机化合物 (VOC) 的水平来检验这一假设。共有 26 人（16 名 EC 用户和 10 名 TC 用户）提供了使用相同协议进行分析的呼出空气样本。我们的测量表明，EC 和 TC 用户排放的粒子数浓度是可比的，但与后者相比，前者排放的粒子的尺寸分布表现出明显更高的可变性。与 EC 使用者相比，TC 吸烟者呼出的空气中 VOC 的负担要高得多。尽管在 EC 用户呼出的空气中测得的一些 VOC 是预料之中的，因为它们直接用于电子烟油，但收集的混合物变化很大（即，因情况而异），其中只有 8 种化合物是常见的所有参与研究的人。相比之下，我们在 TC 吸烟者中确定了 65 种化合物，这些化合物在参与者中很常见。有毒化合物（如苯、乙醛、甲苯、二甲苯、苯乙烯、苯酚、萘等）也存在于 EC 用户呼出的空气中。在呼出颗粒的尺寸分布和来自不同 EC 用户的 VOC 水平中观察到的高度可变性（即，由于不同的设备，操作设置和液体）需要进一步研究，以充分了解 EC 在人类微环境中使用的主流和侧流影响。尽管如此，本研究报告的 EC 使用者呼出的空气中存在高颗粒物排放和即使是痕量水平的有毒 VOC，表明 EC 不应被视为 TC 的无害替代品。