Use of electronic cigarettes (e-cigarettes) impairs indoor air quality and increases FeNO levels of e-cigarette consumers

https://doi.org/10.1016/j.ijheh.2013.11.003Get rights and content

Abstract

Despite the recent popularity of e-cigarettes, to date only limited data is available on their safety for both users and secondhand smokers. The present study reports a comprehensive inner and outer exposure assessment of e-cigarette emissions in terms of particulate matter (PM), particle number concentrations (PNC), volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH), carbonyls, and metals. In six vaping sessions nine volunteers consumed e-cigarettes with and without nicotine in a thoroughly ventilated room for two hours. We analyzed the levels of e-cigarette pollutants in indoor air and monitored effects on FeNO release and urinary metabolite profile of the subjects. For comparison, the components of the e-cigarette solutions (liquids) were additionally analyzed.

During the vaping sessions substantial amounts of 1,2-propanediol, glycerine and nicotine were found in the gas-phase, as well as high concentrations of PM2.5 (mean 197 μg/m3). The concentration of putative carcinogenic PAH in indoor air increased by 20% to 147 ng/m3, and aluminum showed a 2.4-fold increase. PNC ranged from 48,620 to 88,386 particles/cm3 (median), with peaks at diameters 24–36 nm. FeNO increased in 7 of 9 individuals. The nicotine content of the liquids varied and was 1.2-fold higher than claimed by the manufacturer.

Our data confirm that e-cigarettes are not emission-free and their pollutants could be of health concern for users and secondhand smokers. In particular, ultrafine particles formed from supersaturated 1,2-propanediol vapor can be deposited in the lung, and aerosolized nicotine seems capable of increasing the release of the inflammatory signaling molecule NO upon inhalation. In view of consumer safety, e-cigarettes and nicotine liquids should be officially regulated and labeled with appropriate warnings of potential health effects, particularly of toxicity risk in children.

Introduction

Environmental tobacco smoke (ETS) is by far the most significant indoor air quality issue, bearing a health risk by inducing lung cancer and cardiovascular disorders in non-smokers (IARC, 2004, US, 2006). It is also considered as important risk factor for asthma, respiratory infections and sudden infant death syndrome in children (EPA, 1992, EPA, 1997, Raupach et al., 2008). National regulators in USA and Europe have progressively banned tobacco smoking from public buildings, bars, cafés and restaurants which led to improved indoor air quality in these buildings (Bohac et al., 2010, Gleich et al., 2011). The smoke-free policies and constantly surging tobacco prices prompted consumers to look for alternatives to conventional smoking. New products, especially electronic nicotine delivery systems also known as electronic cigarettes or e-cigarettes, have become popular in spite of insufficient data on their safety for both users and secondhand smokers (Etter et al., 2011).

E-cigarettes do not burn tobacco but produce a respirable aerosol without smoke or flame from a battery-powered heater and liquid-containing cartridges (Trtchounian et al., 2010). Depending on the brand, the liquids usually contain nicotine in different concentrations (8.5–22.2 mg/ml) (Cameron et al., 2013), humectants to produce the vapor (especially 1,2-propanediol) and flavors (e.g. tobacco, vanilla, cherry). Despite the growing popularity of e-cigarettes, consumers do not have valid information on the chemical content of liquids or on their safety. In particular, liquids labeled as nicotine-free may contain low levels of nicotine (FDA, 2009), and the risk of impurities (e.g. nitrosamines) is of major concern to health care authorities (FDA, 2009). There is not only a lack of internationally certified manufacturing sites, and liquids freely available via the Internet are not subject to official quality control.

Because e-cigarettes are marketed for delivering nicotine and sometimes other substances, there is a need for regulation, as for other drug delivery devices. Thus far there has been a wide range of responses across countries and states, ranging from no regulation to complete bans (Etter et al., 2011). The empirical basis for these decisions is uncertain, and more research on the health effects of and risks from e-cigarettes must be conducted to ensure that the decisions of regulators, health care providers and consumers are based on scientific evidence.

The aim of our study was to perform a comprehensive exposure assessment by analyzing the indoor air concentration of e-cigarette emissions in terms of particulate matter (PM), particle number concentrations (PNC), volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH), carbonyls, and metals. For this purpose, we simulated a real-world scenario (café-like setting) in an environmentally controlled room with predetermined occupancy density and air exchange rate. Before and after the vaping sessions, the concentrations of exhaled carbon monoxide (eCO) and nitric oxide (FeNO) were measured to reveal acute effects of e-cigarette use on physiological parameters. FeNO has already been used in a previous study on e-cigarettes (Vardavas et al., 2012) and is sensitive to a number of factors including eosinophilic inflammation, airway caliber, mucus production, oxidative stress, and enzyme activity, all of which might be affected by e-cigarettes. Additionally, the uptake of nicotine and other VOC was investigated by analysis of urinary nicotine metabolites and mercapturic acids. To support consumer protection, we furthermore analyzed the chemical composition of the e-cigarette liquids and checked for the presence of impurities (nitrosamines).

Section snippets

Study design

The study was carried out in a room in the office building of the Bavarian Health and Food Safety Authority in Munich, Germany. Room size was 18 m2 and its volume 45 m3. The room contained three tables and a wardrobe (café-like setting), and was operated at an average air exchange rate of 0.56 h–1. The measurements were taken on seven days in July 2012 at the same time of the day. On the first day (control day) the air was monitored without vaping activities and on the following six days with

Results

Table 1 gives the results of the liquid analysis in terms of humectants, nicotine, and other (volatile) organic compounds. All liquids consisted to >90% of the humectants 1,2-propanediol (mean ± SD, 559.2 ± 51.5 g/l) and glycerine (480.3 ± 41.0 g/l). Nicotine levels (22 ± 0.8 mg/ml) were on average 22% above the manufacturers’ declaration of 18 mg/ml, but liquids labeled as nicotine-free had no nicotine present. All e-cigarette solutions contained small amounts of sensitizing chemicals including

Discussion

Since tobacco smoking is being progressively banned from public places worldwide, electronic cigarettes (e-cigarettes) show a rapidly growing market share, although data on their safety for users and secondhand smokers are limited. The present study offers a comprehensive exposure assessment by analysis of the effects of e-cigarettes on indoor air quality in terms of PM, PNC, VOC, PAH, carbonyls, and metals. FeNO levels of the subjects were measured to determine acute effects of e-cigarette

Conflict of interest statement

The authors declare that there are no conflicts of interest.

Acknowledgments

The authors thank all volunteers for participation in the study. The excellent technical assistance of Beate Emmelot and Ludwig Fembacher is greatly appreciated. The study was funded by the Bavarian State Ministry of Health and Cure.

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