Secondhand vaping: the studies

I've done a deep dive into the science of 'secondhand vaping' on my Substack (which you should subscribe to if you haven't already). I look at all the studies that the UK government's vaping ban Impact Assessment refers to, directly or indirectly. Here's the conclusion...

 

Most of the studies are from researchers who are actively looking for risks and who write up their work in a way that emphasises the “potential” harm. They generally fail to provide adequate context by referring to typical readings among active vapers, let alone active smokers, and they rarely refer to the safe thresholds of the substances they are examining (the 2021 study by Amalia et al is one of very few exceptions). That is because the levels recorded are generally considered safe by regulators in workplaces and outdoors (which is where the regulations tend to be applied). Unable to show that the measurements are unsafe or abnormal, the researchers focus instead on an increase in one substance - usually cotinine - and imply that any increase above the baseline must be hazardous.

It should be noted that these are the studies mentioned by organisations such as the WHO who want vaping banned indoors. Weak as it is, they presumably think that it is the best evidence to support their position, but other evidence is available. For example, when the U.S. Department of Health and Human Services sampled the air in a vape shop (where e-cigarette use was obviously heavy in a confined space) it found that all chemicals in the air were below the occupational exposure limit. It expressed concerns about detectable levels of two chemicals (diacetyl and 2,3-pentanedione), but both of these are banned for use in e-cigarette fluids in the UK (and EU).

Similar studies have found that even in very high exposure conditions in a small, non-ventilated vape shop, nicotine concentrations in the air were undetectable and those chemicals that were detectable were at very low (and legal) levels.

A systematic review of the evidence found “no evidence of potential for exposures of e-cigarette users to contaminants that are associated with risk to health at a level that would warrant attention if it were an involuntary workplace exposures” and “no evidence that vaping produces inhalable exposures to contaminants of the aerosol that would warrant health concerns by the standards that are used to ensure safety of workplaces.” And that is to the users of e-cigarettes! “Exposures of bystanders are likely to be orders of magnitude less, and thus pose no apparent concern.”

Public Health England said in 2016 that “there is no evidence of harm to bystanders from exposure to e-cigarette vapour and the risks to their health are likely to be extremely low.” They also said that “e-cigarette use is not covered by smokefree legislation and should not routinely be included in the requirements of an organisation’s smokefree policy”. Why? Because there is no risk to bystanders and vaping bans discourage smoking cessation.

As Prof Peter Hajek, Director of the Tobacco Dependence Research Unit at Queen Mary University of London (QMUL) says:

“While health risks of e-cigarettes to vapers themselves have been estimated at up to 5% of health risks of smoking, health risks to bystanders are most likely reduced by a much bigger margin, and most likely altogether. This is because e-cigarettes release no chemicals into the environment themselves, only what users exhale, and such exhalation has so far not been shown to generate any toxicants at levels that could conceivably affect the health of bystanders.”

There has been a concerted effort by anti-vaping academics to find evidence that ‘secondhand vapour’ is harmful to bystanders. Despite using a variety of methods, they have come up empty-handed, with the partial exception of a few studies that have looked at air quality in unrealistic laboratory conditions. The levels of chemicals measured in the atmosphere and in the bodies of people ‘exposed’ to vaping in everyday situations are not only vastly lower when compared to tobacco smoke, but are lower when compared to everyday activities such as cooking and are consistently below the safe level for indoor and outdoor air quality.

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