Do E-cigarettes Produce Secondhand Smoke, and Is It Harmful?

Do e-cigarettes produce secondhand smoke, and is it harmful? To answer this question, we first need to analyze what secondhand smoke from cigarettes is made of. In fact, cigarette secondhand smoke consists of two types of smoke: one is the smoke exhaled by the smoker, known as mainstream smoke; the other is the smoke produced when the cigarette burns, known as sidestream smoke. Whether sidestream or mainstream smoke, the main components include tar, nicotine, carbon monoxide, and other chemical substances. Among these, tar and carbon monoxide are produced by burning tobacco. The harm of secondhand smoke to the human body is caused by these combustion-related substances.

E-cigarettes directly atomize nicotine, so they do not contain tar or carbon monoxide. As for nicotine itself, it is a naturally occurring alkaloid commonly found in nature; plants such as tomatoes and goji berries also contain nicotine. Nicotine itself can be addictive, but the exact harm caused by inhaling nicotine is still not fully clear. As long as nicotine is used as a raw material, the product contains nicotine. (Of course, some e-cigarettes remove nicotine from the ingredients and use only glycerin and propylene glycol, in which case they contain no nicotine.)

Assuming a cigarette and an e-cigarette contain the same amount of nicotine, which one produces nicotine that is more easily absorbed by others nearby? The answer is the cigarette. The nicotine produced by cigarettes is particulate matter, with particles close to PM2.5, making it difficult to dissipate and easier to absorb. After e-cigarette nicotine is atomized, it forms an aerosol, and that aerosol is quickly diluted in the air. Once diluted, the aerosol is much harder to absorb. Therefore, the vapor produced by e-cigarettes is not the same as cigarette smoke. Finally, the other two main ingredients in e-liquid are propylene glycol and vegetable glycerin, both of which are non-toxic substances, so e-cigarettes do not produce secondhand smoke.

I would also like to correct a few points. The main harmful substances in cigarettes have never primarily been nicotine, but rather carcinogenic substances such as formaldehyde released during combustion. Most people have been misled into thinking nicotine is the main culprit, so in e-cigarettes nicotine naturally becomes the focus of attention as well (if you mind it, you can also choose nicotine-free e-liquid).