Claims of “Passive Vaping Danger” Irritate Scientists

May 21, 2024

We’re facing a “New Danger of Passive Vaping,” according to a recent article in the Economic Times of India. It’s far from alone in flagging this threat, which has also been raised by various researchers, by the likes of the American Heart Association and, and—naturally—by the World Health Organization.

“E-cigarette emissions typically contain nicotine and other toxic substances that are harmful to both users and non-users who are exposed to the aerosols second-hand,” states the WHO, which is known for its anti-vaping stance.

People who vape “could pose serious health risks” to bystanders “exposed to vapors laden with hundreds of toxic chemicals” including carcinogens, states the Economic Times piece.

India has banned nicotine vapes since 2019; in an environment where tobacco harm reduction voices are censored, articles like this support the status quo.

As well as adding to the general, worldwide clamor against harm reduction products, the “passive vaping” narrative has specific implications for policies about whether people can vape in public spaces, and for child protection laws. It is illegal to vape in a car with a child present in jurisdictions as far apart as Alabama and New Zealand.

But a number of scientific experts say the risk has been grossly exaggerated.

“Exhaled vaping aerosol is very diluted (vapers retain 90 percent of the inhaled aerosol) and volatile. Its droplets readily evaporate and gas disperses in a very short time.”

“The chemical emissions from combustion-free nicotine delivery technologies, such as e-cigarettes, are substantially less toxic than the smoke from traditional combustible cigarettes,” Dr. Riccardo Polosa, professor of internal medicine at the University of Catania, Italy, told Filter.

“Additionally, e-cigarette aerosols disperse more quickly in the environment, which results in shorter exposure times,” he added, contrasting this with prolonged exposure from not only tobacco smoke, but also aerosols from everyday products like cooking oils.

So what exactly are the chemicals involved in second-hand vapor, and should we be at all worried?

Dr. Roberto Sussman, a senior researcher and lecturer at the Institute of Nuclear Sciences, National Autonomous University of Mexico (UNAM), is a physicist who has done substantial work around passive vaping.

Sussman told Filter the so-called particles from vapes are liquid droplets made “almost 100 percent of the main compounds propylene glycol (PG) and vegetable glycerin (VG), nicotine and water.”

PG droplets rapidly evaporate, whereas VG and nicotine evaporate at a slower rate, he explained, so VG tends to concentrate terminally in the droplets and PG in the gas from evaporation.

“Exhaled vaping aerosol is very diluted (vapers retain 90 percent of the inhaled aerosol) and volatile,” Sussman continued. “Its droplets readily evaporate and gas disperses in a very short time (under one minute). In such diluted concentrations, VG, PG and nicotine are not toxic to bystanders,” he said, referencing a study about the influence of vaping on indoor pollutants and particles.

“What is missing to make the 100 percent are about 10-20 byproducts,” Sussman said, “in negligible concentrations.”  

The presence of potentially harmful chemicals in trace amounts does not in itself demonstrate harms, when the dose makes the poison. Any purported harms from passive vaping would also need to be set against the public health benefits of making vaping readily accessible to people who’ve switched from smoking, which is exponentially more harmful.

“I am truly concerned that the media is disseminating scaremongering stories about passive vaping, despite the lack of scientific evidence supporting such claims.”

“Unlike passive exposure to side-stream smoking, it’s unsurprising that there is no substantial evidence to suggest that passive inhalation of e-cigarette aerosols poses significant health risks,” Polosa said. “I am truly concerned that the media is disseminating scaremongering stories about passive vaping, despite the lack of scientific evidence supporting such claims.”

Sussman dismissed the Economic Times article as just an “opinion piece.” He noted its lack of scientific references and its reliance on the WHO, which he described as a “massive” source of misinformation on vaping, given that organization’s numerous misleading claims.

The article, Sussman said, made no distinction between particulate matter (PM) from air pollution and exhaled vapor. “The author’s statements are completely in contradiction with the known physical-chemical properties of exhaled vape ‘particles,’ which are liquid droplets … whose physical and chemical properties are completely distinct from those of air pollution PM,” he said. In contrast to the byproducts of vaping, “air pollution PMs originate from combustion sources, stay in the environment (do not evaporate), and their chemical composition is very complex and highly toxic.”

Sussman again referenced the study in explaining how non-vape pollutants in indoor spaces vary, but typically comprise carbon-based compounds categorized as polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). These appear in negligible concentrations in clean or well-ventilated settings.

“In a vaping atmosphere, these compounds appear together with the three compounds inherent [to] vaping,” he continued. “The difference in concentrations among almost all the non-vaping compounds (PAHs and VOCs) between the vaping and non-vaping atmospheres is so small that it is hard to distinguish them from those daily fluctuations of indoor pollution when there is no vaping.”

Independent evidence reviews, published by Public Health England in 2014 and 2015, found ​​”no evidence of harm to bystanders from exposure to e-cigarette vapor and the risks to their health are likely to be extremely low.”

“Public vaping should be treated by vapers as a matter of etiquette and good manners.”

The United Kingdom’s National Health Service is more cautious, stating that “limited evidence available suggests that any risk from passive vaping to bystanders is small relative to tobacco cigarettes,” but advising that “as a precaution, it’s best not to vape around babies and children if you can avoid it.”

Cancer Research UK meanwhile states: “There is no good evidence that second-hand vapor from e-cigarettes is harmful.” The organization notes a lack of research on long-term exposure, but says even this “is unlikely to be harmful.”

As such, and because the odor of vaping, say, might cause annoyance to some people, tobacco harm reduction advocates contend that whether to vape indoors or in public spaces should be seen as a question of considerate personal conduct, rather than something to be legislated against—when bans are liable to target populations that are already disproportionately policed.

“Public vaping should be treated by vapers as a matter of etiquette and good manners,” British advocate Clive Bates, of Counterfactual Consulting, told Filter, “with the decision about whether to allow vaping in a particular place left to owners as they see fit.”

Sussman agreed, likening public vaping to an activity like playing music, with the potential to irritate rather than harm. He said the UK landscapewhere owners of bars and other premises, not the state, decide if vaping is allowed there—represents a good approach. 



Photograph by Vaping360 via Flickr/Creative Commons 2.0

Both The Influence Foundation, which operates Filter, and the Center of Excellence for the acceleration of Harm Reduction, founded by Dr. Polosa, have received grants from Global Action to End Smoking.

Kiran Sidhu

Kiran is a tobacco harm reduction fellow for Filter. She is a writer and journalist who has written for publications including the Guardian, the Telegraph, I Paper and the Times, among many others. Her book, I Can Hear the Cuckoo, was published by Gaia in 2023. She lives in Wales. Kiran's fellowship is supported by an independently administered tobacco harm reduction scholarship from Knowledge-Action-Change—an organization that has separately provided restricted grants and donations to Filter.

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