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. Author manuscript; available in PMC: 2023 Jan 18.
Published in final edited form as: Circulation. 2022 Jan 18;145(3):219–232. doi: 10.1161/CIRCULATIONAHA.121.056777

Figure 1: First to Fourth Generation e-Cigarette Devices.

Figure 1:

From left to right: first generation (“cig a-likes”), second generation (“vape pens”), third generation (“tanks” and “mods”), and fourth generation (“pod mods”) e-cigarette devices. First and second generation e-cigarette devices were tubular and inefficient in nicotine delivery when compared to combustible tobacco products. Third generation devices were customizable and contained larger tanks with larger, higher voltage batteries and were comparable to conventional cigarettes in nicotine delivery efficiency. Fourth generation (e.g. JUUL, PuffBar) devices have smaller tanks (pods) and batteries with decreased nicotine delivery efficiency. However, fourth generation e-cigarettes compensated for lost efficiency by switching from freebase nicotine (used in first-third generation devices) to higher concentrations of nicotine salt, along with benzoic acid. These devices are available in reusable (left) and disposable (right) forms.