This study was the first to our knowledge to assess country differences in social norms towards smoking and vaping among youth and associations with product use. Overall, youth had more pro-vaping than pro-smoking norms. English youth reported the most pro-smoking and least pro-vaping norms overall. Norms were similar in Canada and the US, except more Canadian than US youth reported friend smoking. Smokers had more pro-smoking norms, vapers had more pro-vaping norms, and there were some cross-product associations between norms and use.

Prevalence of friend use of either product was similar overall, with around half of youth reporting friend smoking (47%) and friend vaping (52%), while perceived peer approval of vaping (44%) was almost twice that of peer approval of smoking (23%). Friend smoking and vaping was greater than previous British (East et al., 2018) and US (Barrington-Trimis et al., 2016; Gorukanti et al., 2017) studies, possibly due to the older age of participants in this study. To our knowledge, perceived peer approval of smoking and vaping have not been simultaneously assessed in other studies. The finding that peer approval of vaping was greater than smoking is perhaps unsurprising given that vaping is less harmful than smoking (McNeill et al., 2015) and may be more appealing to youth than smoking given the novelty and range of products and flavors available.

The high prevalence of friend product use and perceived peer approval of vaping is concerning, particularly given the age of respondents, that the majority had never smoked or vaped, and that norms were associated with use. There are concerns that the popularity of vaping may lead never smoking youth to try nicotine (US Department of Health and Human Services, 2016). Between 2017 and 2018, prevalence of vaping increased in Canada and the US, including among never smokers, but did not change in England (Hammond et al., 2019); this mirrors our findings that vaping norms were most positive in the former two countries. It is important that norms are continuously monitored alongside prevalence to explore whether pro-vaping norms could precede any changes in vaping, or smoking.

Friend smoking and peer approval of smoking were more commonly reported by smokers, adding to the large body of evidence that smoking norms influence smoking behavior (Chang et al., 2006; Chapman and Freeman, 2008; Conner et al., 2017; Lotrean et al., 2013; Van De Ven et al., 2007). Friend vaping and peer approval of vaping were more commonly reported by vapers, also similar to previous studies (Gorukanti et al., 2017; Lozano et al., 2019; Thrasher et al., 2016). Interestingly, there was a strong dose-response association between greater vaping behavior and pro-vaping norms in all countries which was not mirrored for smoking.

Considering cross-product norm-behavior associations, friend smoking, friend vaping, and peer approval of smoking were more common among smokers and vapers, while peer approval of vaping was more common among vapers but less common among smokers. This suggests that associations between norms and behavior may not be product-specific, although generally product-specific associations were stronger than cross-product associations, particularly for friend smoking and vaping. Except the association between vaping and friend smoking (Lozano et al., 2019; Morello et al., 2016; Thrasher et al., 2016), the direction of associations are inconsistent with previous studies (East et al., 2018; Lozano et al., 2019). This, combined with the mixed positive and negative associations between norms towards one product and use of the alternative, precludes any firm conclusions regarding the potential of e-cigarettes to renormalize smoking. Further research assessing specific norm-behavior pathways using longitudinal methodology is needed.

Both friend smoking and vaping were more common among youth who used alcohol monthly and were older, although increases in friend vaping emerged earlier than friend smoking. Both peer approval of smoking and vaping were more common among females, and generally all norms were more positive among marijuana users (except peer approval of vaping) and ethnic minorities. Thus, there may be some shared risk factors for holding positive smoking and vaping norms.

The country differences in smoking and vaping norms were surprising. English youth reported more pro-smoking norms than the US despite similar smoking rates (Hammond et al., 2019) and the US having less comprehensive tobacco control policies (ITC, 2018; WHO, 2017). Moreover, friend smoking was higher in Canada than the US, yet peer approval of smoking was similar, contrary to Canada’s lower smoking prevalence (Hammond et al., 2019; WHO, 2015) and more comprehensive tobacco control policies (ITC, 2018; WHO, 2017). However, the finding that English youth reported more pro-smoking norms than Canadian youth does align with prevalence rates (Hammond et al., 2019; WHO, 2015), Canada’s longer history of tobacco control policies (Hammond et al., 2006; ITC, 2018; WHO, 2017) and a recent study among adult daily smokers (East et al., 2019b).

Canada and the US had more pro-vaping norms than England in adjusted analyses, while Canada and the US did not differ. However, at the time of surveying, Canada had the lowest vaping prevalence among this age group (Hammond et al., 2019) and the most restrictive vaping policies (Gravely et al., 2019; ITC, 2018). These results may suggest that vaping policies or prevalence rates may have less influence on social norms than some might suppose, reflecting findings from a recent study in Europe (East et al., 2019a) yet contrary to findings among adult smokers and ex-smokers in England, Canada, the US, and Australia (Aleyan et al., 2019).

The discrepancy between the unadjusted and adjusted country differences in friend vaping warrants further exploration. Despite the adjusted odds of friend vaping being higher in Canada than England, exclusion of smoking and alcohol use attenuated country differences. However, inclusion of alcohol, and marijuana, use is important in studies assessing youth smoking and vaping, since they may serve as a proxy for risky behavior that confounds apparent associations (Kozlowski and Warner, 2017).

It is important to mention that while tobacco control policies in 2017 were generally least comprehensive in the US, and vaping policies most restrictive in Canada, the detailed picture is more complicated. Canada’s vaping restrictions were generally unenforced (Hammond et al., 2015) and after survey administration Canada implemented a new Vaping Products Act which relaxed many restrictions (Health Canada, 2018). Further, some youth also use vaping devices for marijuana or cannabis oil (Cassidy et al., 2018; Thurtle et al., 2017) and around the time of survey administration recreational marijuana use was legalized in Canada and several US states. Both the new Act and marijuana legalization were widely discussed around the time of this survey and may have influenced vaping norms; however, this is only speculation and would be difficult to assess. In addition to national smoking/vaping policies, Canada and the US also have divergent municipal/state/province-level policies (e.g., smoke free legislation, minimum age for legal purchase of nicotine products (US: 18–21; Canada: 18–19)). Moreover, since these data were collected in 2017, vaping environments have changed in Canada and the US: while Canada has relaxed many restrictions (Health Canada, 2018), the US has launched a national youth vaping prevention campaign (Food and Drug Administration, 2019) and proposed banning vaping in some jurisdictions (City Attorney of San Francisco, 2019). Youth vaping prevalence has also increased in these two countries since 2017 (Hammond et al., 2019). Therefore, while this study provides an overview of norms in each country, they may differ at the municipal/state/province-level and may not be generalizable to more recent years.

The findings from this study must be considered in light of several limitations. First, data were cross-sectional, meaning that directionality cannot be inferred, and there is almost certainly a reciprocal relationship between norms and behavior. Second, smoking norms may confound vaping norms and vice-versa; for example, some youth could have pro-vaping norms because they have anti-smoking norms. Future research could assess within-person differences in smoking/vaping norms and their associations with product use. Third, item wording for friend use does not enable differentiation between those with only one smoking/vaping friend and those among whom all friends smoke/vape. Fourth, data were self-reported and may be subject to recall and social desirability biases, which may be particularly pronounced when asking about peer’s nicotine use and norms. However, the fact that this was an anonymous, self-administered survey may alleviate some of this concern. Fifth, as mentioned above, Canada and the US have differing policies at the municipal/state/province-level which were not accounted for in analyses.

Despite these limitations, this study has important strengths. First, although participants were recruited from non-probability-based commercial samples, sample weights were incorporated to enhance representativeness and both weighted and unweighted estimates were similar to national benchmark surveys in each country (Hammond et al., 2019). Second, the sample was large, allowing for assessment of different user status groups and interactions with country. Third, this study is the first to compare social norms towards smoking and vaping and their associations with product use across countries, providing a novel contribution to the literature.