Secondhand Aerosol From Electronic Cigarettes

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UPDATE: Recent illnesses have been associated with use of e-cigarettes (vaping). Since the specific causes of these lung injury cases are not yet known, the Centers for Disease Control and Prevention (CDC) recommends refraining from all vaping products.

The clear risks associated with secondhand smoke have led state legislatures throughout the United States to ban smoking in public places. But what about electronic cigarettes and vaping?

Secondhand smoke kills tens of thousands of people every year in the United States alone. It can cause sudden infant death syndrome and lung issues in children. In adults, it can lead to serious health conditions later in life, such as stroke, heart disease, and lung cancer—even in people who never smoked themselves.

There’s still a lot we don’t know about the harms of secondhand vaping, but research suggests that bystanders who breathe in the aerosol might be exposed to many of the same toxins found in e-cigarettes and even some found in traditional tobacco.

woman smoking vape reads tablet

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Secondhand Vaping

Just like people around smokers can breathe in cigarette smoke, it’s possible to breathe in e-cigarette aerosol if you’re around someone vaping. This is called secondhand vaping, and there isn't a lot of published research yet on how inhaling this aerosol affects the body, especially among adolescents.

About a quarter of middle and high school students surveyed in 2017 said they had been around someone vaping at least once in the past 30 days. Some of them used electronic cigarettes themselves, but roughly one in five didn’t.

Toxins Found in Vaping Aerosol 

Vaping doesn’t produce as many harsh chemicals as smoking, but research suggests it still likely contains pollutants.

Some ingredients found in vaping aerosol include:

  • Formaldehyde: This is a compound created when solvents like propylene glycol and glycerin are heated up by the vaping device. It’s readily absorbed by the lungs and can be toxic—possibly even cancer-causing—in high doses.
  • Acrolein: This is a compound made when glycerin is heated by the coils in an e-cigarette. It can irritate the respiratory tract, including the delicate tissue of the lungs.
  • Benzene: This is a colorless, sweet-smelling, organic compound that can irritate the lungs. It is also found in car exhaust.
  • Diacetyl: This is a common food additive that is sometimes included in vaping fluids to add a rich, buttery flavor (for example, butterscotch or caramel). It’s been linked to a serious lung disease known as “popcorn lung,” which was first seen in individuals working in a popcorn factory where diacetyl was used.
  • Heavy metals: Ingredients such as lead, nickel, or tin can occur. E-cigarette devices use metal coils to heat the vaping fluid, and over time, small amounts of metals can sometimes get into the aerosol after repeated use at high temperatures.

While the person vaping will breathe in the full brunt of these toxins, some will be exhaled into the air.

Factors Affecting Secondhand Vaping

The amount and type of toxins released into the air around vapers can depend on a variety of factors, including the brand of vaping fluid, the voltage of the vaping device, the number of people vaping at the same time, and how frequently or intensely they’re vaping.

For a long time, e-cigarettes and other electronic aerosolizers weren’t regulated by the Food and Drug Administration (FDA). They only came under the purview of the FDA in 2016, after they had been on the market for nearly a decade. Prior to that, it was the Wild West, where a variety of companies started making and selling products with their own personal spin.

As a result, there are a lot of differences among the various devices and fluid containers. These variations include:

  • Device design: How the devices and e-fluids are made, such as what metals they use for the heating coils, and how likely that metal is to leech into the aerosol
  • Voltage: How hot the devices get when activated, which can affect what kind of and how many compounds appear in the aerosol
  • E-fluid composition: What flavoring ingredients, solvents (which create the white, cloud-like “vapor”), and additives (such as nicotine or THC) are used

The makeup of these devices—combined with individual or group vaping patterns—can significantly impact what pollutants get into the air and how many.

One study, for example, found that under most conditions, someone vaping at home all day didn’t change the air quality a terrible amount unless they vaped intensely at a high voltage. At that point, levels of formaldehyde exceeded limits set by the California Office of Environmental Health Hazard Assessment (OEHHA), though other compounds didn’t come close.

However, when they looked at other scenarios, such as bar settings where many people were vaping, the researchers found that the concentration of toxins in the air was generally much higher than residential settings. The more people were vaping and the higher voltages were used, the worse the air quality. In some scenarios, levels of both formaldehyde and acrolein were above OEHHA safety standards for bar employees.

Other studies suggest that while using e-cigarettes sends pollutants into the air, the concentration of these toxins drops quickly after someone stops vaping (much faster than cigarette smoke), but that doesn’t mean that the risk has gone away. Once out in the air, not all of these toxins will act the same way. Some, for example, will settle on surfaces, such as carpets or furniture, where small children might touch them or inadvertently ingest them when placing contaminated objects in their mouths.

Potential Health Effects of Secondhand Vaping

It’s still not clear how the toxins found in vaping can affect the health of non-vapers, especially long-term. The limited research available so far has largely focused on immediate health effects. That said, there are some concerns about how repeatedly inhaling e-cigarette aerosol over an extended period of time could affect bystanders’ long-term lung function and risk of allergic reactions.

Secondhand Vaping and Lung Function  

Short-term studies haven't found evidence that exposure to secondhand aerosol from e-cigarettes hurts lung function, with one notable exception. Researchers found that people who were around vaping aerosol showed increases in the serum cotinine, which is a marker that someone was exposed to nicotine (an ingredient often found in e-cigarettes). Given the long list of health risks posed by nicotine, more research needs to be done on how this exposure could affect someone’s lungs long-term like it can with secondhand smoke.


Another potential risk posed by vaping indoors is allergic reactions, especially among children. According to research, roughly 8% of kids in the United States have food allergies. Nuts (a common food allergy) are sometimes used to make added flavors in vaping fluids. If a child ingests or touches fluids with an allergen in it, they could have a reaction. This, however, is only a theoretical risk for now, as little research has been done on the topic.

Likewise, the U.S. government has taken steps to restrict most flavored vaping products, effective in 2020. While this should reduce the number of flavored cartridges available in the United States, the guidelines are limited to products submitted for market authorization and don’t include those made at home or purchased online from other countries.

Secondhand Vaping as a Gateway 

In addition to the still uncertain health risks associated with breathing in e-cigarette aerosol, being around people who vape could have other consequences—particularly for adolescents who are more likely to be influenced by social norms and visual cues. A concern among some public health professionals is that seeing other people vape could encourage young people to take up vaping themselves and possibly help to renormalize tobacco use in general.

A Lot of Unknowns 

Researchers spent decades studying the health consequences of secondhand smoking. It might be a while before we have a clear picture of how secondhand vaping can impact a person’s long-term health, especially for young children.

While research shows the concentrations of formaldehyde and other substances likely fall below OEHHA standards inside the home, the levels set by these safety standards are designed for healthy adults in a workplace—not children, pregnant women, older adults, or people with chronic health issues. What might be considered safe for the average workplace employee could still pose serious health risks for more medically vulnerable populations.

Laws Banning Vaping in Public Places

To lower the potential risks posed by secondhand aerosol exposure from vaping, some U.S. states, territories, and cities have started restricting where people can vape. According to the American Nonsmokers’ Rights Foundation, as of January 2020, 19 states and over 900 municipalities have included e-cigarettes and other electronic smoking devices in their laws and policies banning smoking in certain environments, such as schools or workplaces.

Some of these laws offer exceptions. For example, in New York and Vermont, vaping is prohibited in all smoke-free venues (like workplaces, bars, restaurants, and gambling facilities) except e-cigarette stores.

A Word From Verywell

There isn’t a lot of research done on the health harms of exposure to secondhand aerosol from vaping. Early studies suggest that the risks posed by secondhand vaping are substantially lower than secondhand smoking, but that's a low bar considering how hard cigarette smoke is on the body. The aerosol produced by electronic cigarettes and other aerosolizers can still contain potentially dangerous toxins, including nicotine. We don’t yet know how these toxins affect the body long-term, particularly for young children who are exposed to vaping aerosol for many years and during crucial periods of development.

If you or someone you know is addicted to vaping, talk to a healthcare provider right away about what might help you quit or reduce how much you use electronic cigarettes.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Robyn Correll, MPH
Robyn Correll, MPH holds a master of public health degree and has over a decade of experience working in the prevention of infectious diseases.