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Should You Worry About Breathing Secondhand Vapor?

Jim McDonald
June 9, 2023

Because e-cigarettes have only been available in the United States and Europe for a little over a decade, we don’t fully understand the long-term effects of vaping on users.

However, we do know enough about the likely health risks of vaping—based on the safety profiles of the chemicals involved—to understand that vaping almost certainly doesn’t pose risks to users as great as those of combustible cigarettes.

We may actually know more about the risks to bystanders than to vapers themselves. Based on standards for workplace exposure to inhaled chemicals and metals, scientists can estimate whether the toxic constituents present in “secondhand vapor” might make vaping harmful to “accidental vapers.”

So far, there’s no evidence that secondhand (or passive) vaping is a serious threat to the health of non-vaping bystanders.

What is secondhand vapor?

Secondhand vapor (which is technically an aerosol) is the vapor exhaled into the atmosphere by an e-cig user. Like secondhand smoke, it lingers in the air long enough that anyone in the same room (assuming the room is small enough) is likely to inhale some of the exhaled aerosol. As the name indicates, the bystanders are not inhaling secondhand (or passive) smoke—because secondhand e-cigarette vapor simply isn’t smoke.

Smoke is a product of combustion. Burning any substance with fire—including wood, leaves, a building, or any plant material, including tobacco—produces volatile gasses, carcinogenic solid particles, carbon monoxide, and a mixture of dangerous byproducts that in cigarette smoke is called tar. Secondhand smoke isn’t as dangerous as inhaling directly from a cigarette, but regular and prolonged exposure to it is considered a serious hazard.

E-cigs heat e-liquid with a small metal coil housed in an atomizer, and the heat turns the e-juice into the vapor you see. E-cigarette vapor doesn’t have any carbon monoxide or tar, and the particles in the aerosol are liquid rather than solid. Dangerous chemicals and metals are found in vapor, but only in tiny quantities. The levels of toxicants are minute compared to those found in smoke, which means the dangers of secondhand vaping are less significant.

What’s in secondhand vapor?

If you encounter people vaping inside a house, all of the secondhand vapor you see comes out of the mouths of the vapers in the room. There is no side stream “vape smoke” like there is side stream tobacco smoke from cigarettes—no constant emission of vapor pouring from the device when it’s not being used. The user has to inhale to produce vapor. And by the time the vaper exhales, the vapor contains much less of all the substances that were in the inhaled vapor, because most of it is absorbed by the user’s mouth, throat and lungs. There simply aren’t enough of the already-scarce toxicants left over to make secondhand vapor a concern.

Aside from propylene glycol and glycerin (PG and VG)—the two glycols that make up the base of virtually all e-liquids—what vapers exhale into the air doesn’t contain high levels of anything. According to Drexel University toxicologist Igor Burstyn, while the contents of e-cig vapor inhaled by users “justifies surveillance,” there is so little contamination in exhaled vapor that there is unlikely to be any risk for bystanders.

What isn’t inhaled falls to the ground quite rapidly. Those concerned with “thirdhand nicotine”—the unabsorbed nicotine that lands on floors and furniture—might make a case for not vaping around kids or pets who might lick the surfaces. But there’s not much nicotine left in the settled residue. According to a 2016 University of California-San Francisco study, 93.8 percent of the inhaled nicotine is retained by the user, and is not part of the exhaled vapor.

Even if secondhand vaping can’t be proven harmful to others, the concerns of family and friends need to be respected.

“Nicotine from exhaled vapour can be deposited on surfaces, but at such low levels that there is no plausible mechanism by which such deposits could enter the body at doses that would cause physical harm,” Royal College of Physicians researchers noted in that organization’s comprehensive 2016 review of e-cigarette science.

Particles from vaping, which are liquid rather than solid like smoke particles, don’t seem to affect air quality at all. In a 2017 University of California-San Diego study that analyzed the air in 193 low-income family homes, the researchers found that smoking tobacco or marijuana, cooking, and burning candles all affected particle counts in the homes. But vaping (which was being done in 43 of the homes) had no measurable effect on the indoor air quality.

Even studies of the air in vape shops have shown that levels of toxicants are below occupational exposure limits. In fact, the National Institute for Occupational Safety and Health (NIOSH—a CDC agency) found that even in a shop where 13 customers vaped during the day, the flavoring chemicals and formaldehyde measured in the air were all below the allowable exposure limits, and nicotine was practically absent from the samples.

Is secondhand vapor dangerous?

In Public Health England’s updated 2018 evidence review, the agency’s experts analyzed several new studies of passive exposure that had been published since the original 2015 PHE e-cig report. They concluded—again—that “to date there have been no identified health risks of passive vaping to bystanders.”

Igor Burstyn’s study of the possible dangers of secondhand vaping attempted to “estimate potential exposures from aerosols produced by electronic cigarettes and compare those potential exposures to occupational exposure standards.” His conclusion: “Exposures of bystanders are likely to be orders of magnitude less, and thus pose no apparent concern.”

Orders of magnitude are multiples of 10. Therefore, 10, 100, 1,000, 10,000, and so on. What Burstyn means is that the exposure to toxic chemicals in secondhand vapor is so slight as to pose no real threat. Whatever the risk may be to the users themselves, it is 10 or 100, or even 1,000 or 10,000, times lower for the bystander.

Does that necessarily mean that vapers should feel free to vape everywhere without regard to the wishes of others? No!

Even if secondhand vaping can’t be proven harmful to others, the concerns of family and friends need to be respected. Obviously, if a spouse or visitor objects, vapers should be courteous and thoughtful, and take the vape outside. Clearly, if someone in the home has asthma or another respiratory condition, secondhand vape is best avoided, since we know PG and some flavorings can irritate the airways.

Children, of course, don’t get to make an informed choice about what they breathe, so vapers should use good judgement and be more cautious than they might be around adults. There are no secondhand vapor studies that specifically measure the lung functions of babies or young children after daily vape inhalation. Vapers shouldn’t experiment on their kids.

Smokers created vaping without help from the tobacco industry or anti-smoking crusaders, and I believe vapers have the right to continue innovating to help themselves. My goal is to provide clear, honest information about the challenges vaping faces from lawmakers, regulators, and brokers of disinformation. I’m a member of the CASAA board, but my opinions aren’t necessarily CASAA’s, and vice versa. You can find me on Twitter @whycherrywhy
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Jimbob
Jimbob
5 years ago

Thanks for the informative article. And especially thanks to the smart folks who invented vaping. I was dumb enough to start smoking when I was a teenager. Kept at it for over 20 years, and failed at quitting I don’t know how many times. Decided to grab an e-cig finally a while back once the technology started getting good, and it was one of the best moves I’ve ever made. Started out with a high nicotine liquid and slowly tapered down to no nicotine liquid. Stuck with that for a bit, and one day forgot my vape when I went… Read more »

John Canary
John Canary
5 years ago

I found this very useful! Thanks for taking the time to write this.

George torres
George torres
5 years ago

We all know second hand smoke is no good for you. I can tell you i cant breathe after being in it for very little time. I also believe it is inconsiderate vaping in a room with a non vapor

Alexis
Alexis
5 years ago
Reply to  Jim McDonald

I know by experience that the vape that my son and friends exhales does cause me to cough and it irritates my throat. I also know that it leaves a film on my vehicles windows. If it does this then I would say there is more to it than someone is saying. That also since they’ve been doing it they cough and my sons tonsils [are enlarged] but again no proof, but more research needs to be done before we lead many to the grave or serious medical conditions because of our ignorance.

Holly
Holly
6 years ago

great article

Rose
Rose
5 years ago
Reply to  Jim McDonald

Reading the comments on this article was one laugh riot after another. It’s interesting to see how people react to an article citing facts as a tool for enabling addicts. I’m sorry to say, but if you’re related to or involved with someone who Vapes and they site articles like this to undermine you when you voice your discomfort, that particular vaper is a dick. But the reality is that while that vaper may be being an ass, that doesn’t invalidate what they’re saying or by extent the information source they’re using. Trying to correlate unrelated illnesses with the onset… Read more »

VooDooMamaJuJu
VooDooMamaJuJu
9 months ago
Reply to  Rose

For some reason I read this in Mindy Kaling’s voice. Kuddos, Boss B. I love it.

Non
Non
1 year ago
Reply to  Rose

The article is biased and minimizes the negative effects of vaping to the vaporer & by stander. That stuff is dangerous!

Privatepilot
Privatepilot
1 year ago
Reply to  Jim McDonald

The only thing I hear from that last commenter is crickets. I’m sire they’re just gathering facts.

Andrea
Andrea
5 years ago
Reply to  Rose

Yes!!!!!
Also, in the spirit of lacking….add reading comprehension to your list

Mom2boys
Mom2boys
4 years ago

I wonderd if vaping around my kids would be harmful. Even tho this suggests not i wont. I found this article very interesting.

Jeremy Mann
Staff
Jeremy Mann
4 years ago
Reply to  Mom2boys

Hi Mom2boys, I’ve wondered the same thing a few times. I have two little ones. A toddler and a 1st-grader. I guess parents always worry. 🙂 But as soon as I allow myself to stress about a little bit of vapor, I remember the other things I do. For example: I fry food in my house, which means actual oil is in the air. That’s a common but sketchy thing to do inside.“Such aerosols, containing fatty acids, irritate the airway mucosa, and can cause pneumonia.” And that’s just from short term exposure. I try not to do this often. And… Read more »