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E-cigarette vapor exposes people sharing a room with an e-cigarette user to contaminants, including nicotine, particulates and hydrocarbons. Variation in product contents, designs and emissions suggests that some produce little toxicant exposure, whereas others may pose greater risks. However, the risks to health appear likely to be far lower than from indoor exposure to tobacco smoke.



E-cigarette use produces a visible vapor that is usually able to be smelled, depending on the flavors and other contents of the fluid. The vapor is discharged into the air only when the user exhales (i.e. there is no sidestream vapor), in contrast to tobacco cigarettes that discharge smoke continuously while kept alight, and when the user exhales.

The emissions discharge water, volatile organic compounds (VOCs) and nicotine into indoor air at levels far lower than found with tobacco cigarettes (Schripp et al., 2013).

Schober et al. (2014) measured levels of potential e-cigarette pollutants in a ventilated room while volunteers consumed e-cigarettes with and without nicotine for two hours and found a change in air quality. The concentration of polycyclic aromatic hydrocarbons (PAH) in the indoor air increased by 20%, while particulate numbers also increased. The authors concluded that exposure to e-cigarette pollutants might be a health concern, as fine and ultrafine particles might be deposited in the lung.

There is a limited body of published research on the health effects of ‘second hand’ exposure to e-cigarette vapor. McAuley et al. (2012) assessed indoor air concentrations of common tobacco smoke by-products (VOCs, carbonyls, PAHs, nicotine, TSNAs, and glycols) emitted by generic e-cigarettes using four different high nicotine e-cigarette liquids (‘e-liquids’), and compared the results with those from analysis of tobacco cigarette smoke tests; they then undertook risk analyses based on dilution into a 40 m3 room and standard toxicological data. This assessment revealed no significant risk of harm to human health from e-cigarette emissions. In contrast, the tobacco smoke analyses mostly exceeded risk limits (McAuley et al., 2012). Flouris et al. (2013) exposed healthy volunteers to ‘second hand’ e-cigarette vapor for one hour and found small increases in serum cotinine but no significant changes in lung function.  No studies have been conducted on the impact of longer second-hand exposures, exposures in children or third-hand exposures.

Any risks to health from second hand e-cigarette vapor are likely to be far lower than from exposure to tobacco smoke, given the constituents, their toxicity and exposure times (Burstyn, 2014).



Burstyn I. Peering through the mist: systematic review of what the chemistry of contaminants in electronic cigarettes tells us about health risks. BMC Public Health. 2014 Jan 9;14(1):18.

Flouris AD, Chorti MS, Poulianiti KP, Jamurtas AZ, Kostikas K, Tzatzarakis MN, Wallace Hayes A, Tsatsakis AM, Koutedakis Y. Acute impact of active and passive electronic cigarette smoking on serum cotinine and lung function. Inhal Toxicol. 2013 Feb;25(2):91-101.

McAuley TR, Hopke PK, Zhao J, Babaian S. Comparison of the effects of e-cigarette vapor and cigarette smoke on indoor air quality. Inhal Toxicol. 2012 Oct;24(12):850-7.

Schober W, Szendrei K, Matzen W, Osiander-Fuchs H, Heitmann D, Schettgen T, Jörres RA, Fromme H. Use of electronic cigarettes (e-cigarettes) impairs indoor air quality and increases FeNO levels of e-cigarette consumers. Int J Hyg Environ Health. 2013 Dec 6. pii: S1438-4639(13)00153-3.

Schripp T, Markewitz D, Uhde E, Salthammer T. Does e-cigarette consumption cause passive vaping? Indoor Air. 2013 Feb;23(1):25-31.

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