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to nicotine smoke as well as illicit drugs. Having said that, more research is needed in the area of substance use via alternative drug delivery systems, in order to clearly understand the mechanisms of their use as well as the risks posed by e-cigarettes. The present study also showed that marijuana users were significantly more likely to be past 30-day e-cigarette users, compared to non-users. Some studies suggest that vaping of cannabis extracts is becoming more common among marijuana users [19, 35, 36] due to its perception of being less harmful than the traditional burning to smoke methods [4], being easier to disguise due to reduced odours [35], and stimulating less throat irritation upon smoking [37]. Additionally, it is important to note that the current study utilizes results from a survey conducted in 2017, when cannabis was still considered an illegal substance in Canada. In October of 2018, the Cannabis Act legalized the possession and use of cannabis across the nation. This may have implications for the association between marijuana and e-cigarette use in the coming years, and the authors predict that this association will become exacerbated with time. Finally, the association between using alcohol and e-cigarettes has also been noted in other studies [20–22]. However, it is unclear what underlies this association. Hershberger et al. (2016) suggests that the combined use might exist to offset the sedating effects of alcohol via nicotine, while increasing the dopaminergic reward system stimulation through the combination of both substances [38]. While substance use and e-cigarette use were common in the current study, more studies are required to assess the temporal order of these two behaviors. Among the tobacco exposure and use variables, those who had one or more smokers in their household were significantly more likely to have used e-cigarette in the past 30-days, as compared to those belonging to non-smoking households. This is in line with the longitudinal study conducted by Gorini et al. (2016), which found that children and adolescents who belonged to smoking households were two times more likely to become cigarette smokers as young adults, as compared to those who belonged to smoke free households while growing up [39]. It is then possible that witnessing smoking behaviors by close family members might normalize smoking related behaviours, leading to an increased uptake of e-cigarette smoking among younger populations [40]. Furthermore, it is also plausible that exposure to second hand smoke may itself play a role in uptake of e-cigarettes [41]. Those who reported being current tobacco smokers were significantly more likely to be e-cigarette users. These results were expected and are similar to other studies that have found that the combined use of the traditional cigarette and e-cigarettes is common among adolescents and young adults [42–44]. Although, the reasons for the combined use of traditional cigarettes and e-cigarettes are unknown in this study, a study conducted by Kong et al. (2015) among young adults and adolescents, found that commonly stated reasons for using e-cigarettes along with traditional cigarettes included their affordability, the belief that they had reduced health risks, availability of different flavours and the ability to use them in different settings [45]. Among the demographic and health related variables, youth aged 15–17 and those aged 18–21 were significantly more likely to be past 30-day e-cigarette users as compared to those aged 22–24. Findings from Reid et al. (2015) were consistent with our findings and also showed that prevalence of e-cigarette was the highest among young Canadians, particularly between the ages of 15–19 and reported that this association subsequently decreased with increasing age [46]. Similar trends have also been seen in the United States. A study by Cullen et al. (2018) reported one in every five high school students in United States had tried e-cigarettes in the past 30 days in 2018. Following such reports, the U. S Surgeon General, Jerome Adams, declared e-cigarette use among youth an ‘epidemic’ in the country and pushed for higher officials to take action [47]. Adolescents’ perceptions of e-cigarettes’, especially flavored e-cigarettes, as being less harmful and not containing nicotine, combined with a greater propensity of experimentation and risk taking behaviors associated with adolescence, may explain the higher rates of e-cigarettes use among minors seen in this study [27, 48]. Among other sociodemographic and health related factors, males were more likely to have used e-cigarettes in the past 30-days as compared to females. Many studies have also shown similar results [21, 42, 49]. While the reasons for this finding could be multifaceted, a study conducted in the United States by Coleman et