In many countries, including Australia, the use of e-cigarettes is growing, with the highest proportions of users among current smokers. 1-5
18B.3.1 Trends in use of e-cigarettes in Australia
The National Drug Strategy Household Survey asked respondents about e-cigarettes for the first time in 2013, and in 2016 and 2019, asked additional questions about frequency of use. Prevalence of ever-use of e-cigarettes among Australian smokers, non-smokers (including ex- and never smokers) of various age groups and totals for persons 14 years and over and 18 years and over for all three survey years is set out in Table 18B.3.1.
Lifetime e-cigarette use by smoking status and age, 2013 and 2016
Sources: National Drug Strategy Household Surveys 2016 key findings, Table 8 2 and 2019, Table 2.19 1
*Estimate has a relative standard error of 25% to 50% and should be used with caution
# Statistically significant change between 2013 and 2016, or between 2016 and 2019.
^ 2013 survey youngest age group included 12–17-year-olds however 12 & 13-years olds were not surveyed in 2019
(a) Smoked daily, weekly or less than weekly.
(b) Includes both those who have never smoked more than 100 cigarettes and those who have smoked more than 100 cigarettes but report no longer smoking at time of survey
Note: The question about lifetime use of electronic cigarettes was modified in 2016 and may have impacted how people responded question.
About 11% of the general population aged 14 and over reported in 2019 having ever used e-cigarettes. At 26.1%, lifetime use was highest among young adults aged between 18 and 24 years, with lower use among older age groups. Lifetime use of e-cigarettes significantly increased between 2013 and 2016 both among adult smokers (from about 18% to about 31%) and non-smokers (never + ex-smokers; from about 2% to about 5%), and across all age groups except for the oldest. Use between 2016 and 2019 increased further among adult smokers (from about 31% to 38%) and between non-smokers (from about 5% to almost 7%). In 2016, the highest rates of ever use appeared to be among 18–24-year-olds (49.1% and 13.6% of smokers and non-smokers, respectively, compared to 30.8% and 4.7% in the total adult population). In 2019 rates among 18–24-year-olds had increased to 63.9% of smokers and 19.6% of non-smokers.
Frequency of e-cigarette use by smoking status in 2019 is presented in Table 18B.3.2. The overall rate of ever use among never smokers increased between 2016 and 2019, with 94.8% of adult never smokers reporting that they had never tried e-cigarettes in 2019 (compared with 96.1% in 2016 and 98.7% in 2013 6 ). Among ex-smokers, 11.4% reported ever-use, compared with 7.5% in 2016 and 3.1% in 2013. 6
More than one-third of smokers had tried e-cigarettes in 2019, and 7.8% reported current use (daily, weekly, or monthly).
Frequency of e-cigarette use, people aged 14 years or older, 2016 (per cent)
Source: National Drug Strategy Household Survey 2019, Table 2.22 1
*Estimate has a relative standard error of 25% to 50% and should be used with caution
** Estimate has a high level of sampling error (relative standard error of 51% to 90%), meaning that it is unsuitable for most uses
(a) Smoked daily, weekly or less than weekly.
(b) Smoked at least 100 cigarettes (manufactured and/or roll-your-own) or the equivalent amount of tobacco in their life, and reported no longer smoking.
(c) Never smoked 100 cigarettes (manufactured and/or roll-your-own) or the equivalent amount of tobacco
Frequency of current use of e-cigarettes by age group and smoking status in 2016 and 2019 is set out in Table 18B3.3.
Prevalence of current use(a) of e-cigarettes by age, 2016 and 2019 (per cent)
Source: National Drug Strategy Household Survey 2019, Table 2.4 1
*Estimate has a relative standard error of 25% to 50% and should be used with caution.
** Estimate has a high level of sampling error (relative standard error of 51% to 90%), meaning that it is unsuitable for most uses.
# Statistically significant change between 2016 and 2019.
(a) Includes people who reported smoking electronic cigarettes daily, weekly, monthly or less than monthly.
(b) Includes people who reported smoking combustible cigarettes (manufactured and/or roll-your-own) daily, weekly or less than weekly.
(c) Includes those who have never smoked more than 100 combustible cigarettes (manufactured and/or roll-your-own), and those who have smoked this amount of combustible tobacco and report no longer smoking.
Further analysis conducted with data from the 2016 National Drug Strategy Household Survey showed that individuals who were male, younger, had higher psychological stress and were current smokers were more likely to be e-cigarette users. Smoking status had the strongest relationship with e-cigarette use. 7 Another survey, this time looking at young Australian adults (18-25-years-olds), found positive expectancies about e-cigarettes were associated with increased curiosity and intention to use e-cigarettes. 8
An online community survey of adults conducted in New South Wales in early 2016 found that 13% had ever used an e-cigarette and, of those, 34% had used an e-cigarette in the past month. Among ever e-cigarette users, 4.6% reported regular daily use over the previous month. Participants who were younger, as well as current and ex-smokers, were more likely to have used e-cigarettes, while women with higher levels of education and income were less likely. 9
Among Australian secondary school students, in 2017, 14% reported that they had ever used an e-cigarette. Use was higher with age, from 5% of 12-year-olds to 22% of 17-year-olds, and boys were significantly more likely than girls to report ever-use. Of those who had tried e-cigarettes, younger students were more likely to have used them recently. About 37% of 12-to-15-year-old users and 27% of 16-and-17-year-old users reported vaping at least once during the past month. Younger vapers were also more likely to have used e-cigarettes at least three times in the past month (12–15: 16%; 16–17: 10%). 10
In 2016, 3%of all students had used e-cigarettes exclusively, while 11% reported having concurrently used e-cigarettes with tobacco cigarettes and/or shisha-tobacco. Of the 14% of students who had ever used an e-cigarette, 12% used them exclusively, 55% had used shisha-tobacco, and 65% had smoked tobacco cigarettes at least once in their lifetime. Of the 20% of students who had smoked tobacco cigarettes in their lifetime, 47% had ever used e-cigarettes. 11
Researchers have also examined the extent of e-cigarette use and understanding among Australian Aboriginal and Torres Islander smokers, and found that in 2013–14, about one fifth (21%) had tried e-cigarettes. Forty-one per cent had never tried e-cigarettes, and the remaining 38% had not heard of the products. 12
18B.3.2 International trends in use of e-cigarettes
International Tobacco Control (ITC) Surveys data show wide variation in the prevalence of use of e-cigarettes between countries surveyed, which may be attributable to a range of factors, including but not solely differences in regulatory approaches. In a study published in 2014, there was considerable cross-country variation by year of data collection and for self-reports of ever having tried e-cigarettes (Australia, (20% in 2013), Malaysia (19% in 2011), Netherlands (18% in 2013), United States (15% in 2010), Republic of Korea (11% in 2010), United Kingdom (10% in 2010), Mexico (4% in 2012), Canada (4% in 2010), Brazil (3% in 2013), and China (2% in 2009)), and in current use (Malaysia (14%), Republic of Korea (7%), Australia (7%), United States (6%), United Kingdom (4%), Netherlands (3%), Canada (1%), and China (0.05%)). 13 , 14 Another ITC study found that in 2014, prevalence of current e-cigarette use in the UK was more than twice that of Australia (28.2% vs. 11.9%), and prevalence of daily use in the UK was about four times that of Australia (9.2% vs. 2.5%). 15 Findings from the 2016 ITC survey of adult smokers and/or e-cigarette users in the US, England, Australia and Canada showed that 11% were dual users (people who both smoke and use e-cigarettes). 16 The same survey showed that daily vapers most commonly used refillable nicotine vaping products, generally containing flavours and nicotine. 17 Current use of e-cigarettes among adult never-smokers appears to be consistently less common than among smokers, with reported overall prevalence of less than 1% in the UK, 5 Australia, 2 New Zealand, 18 Canada, 19 and the US. 20
In 2016 in the US, 15.4% of adults had ever used an e-cigarette, and 3.2% currently used e-cigarettes; 20 3.8% of men and 2.6% of women reported being a current user. 21 Adults aged 18–24 years were the most likely to have ever used an e-cigarette (23.5%) and to currently use e-cigarettes (4.5%); the percentages declined steadily with age. Across all age groups, fewer than one quarter of adults who had ever used an e-cigarette reported current use. 20 Between 2014 and 2018 the percentage of US adults that had ever used a cigarette increased from 13.0% to 15.7 % 22 In 2015, among current e-cigarette users (3.5%), 58.8% also were current smokers, 29.8% were ex- smokers, and 11.4% were never smokers. Among current e-cigarette users aged 45 or over, almost all (98.7%) were either current or ex-smokers, and 1.3% had never been smokers. In contrast, among current e-cigarette users aged 18–24 years, 40.0% had never been cigarette smokers. 3 Another study found that in 2016, 1.4% of never smokers reported vaping, and of these users, about 60% were young adults aged 18 to 24. 23 Unlike older age groups, where prevalence remained steady, the percentage of current e-cigarette users increased from 5.1% of 18–24-year-olds in 2014 to 7.6% in 2018. 24 , 25 Among current e-cigarette users in 2012-13, one survey found that use was most commonly infrequent (fewer than 4 days per month;38.1%) while 29% reported daily use. 26 Within the US, current e-cigarette use by state was highest in Oklahoma (6.7%) and lowest in DC (2.4%) as of 2016. 27
Despite the sale and advertisement of e-cigarettes being banned in Mexico, a nationally representative survey conducted in 2016 found 1.1% of teenagers, 0.3% of adult non-smokers and 4.5% of adult smokers were current users. 28 In Brazil in 2015, 0.46% of the population were e-cigarette users. 29
In 2015, 13.2% of Canadians aged 15 and over reported having ever tried an e-cigarette; 3.2% had used one in the past 30 days, and 1.0% reported daily use. Use of e-cigarettes increased significantly between 2013 and 2015 (from 8.5% to 13.2%), and prevalence was greater among smokers: 51.0% of current smokers had ever used e-cigarettes in 2015, compared to 7.6% of non-smokers (including ex- and never-smokers); past-month use was 15.5% among current smokers and 1.4% among non-smokers. 19
In the UK in 2019, it was estimated that 7.1% of adults were currently using e-cigarettes, compared with 1.7% in 2012. Of these, just over half (54.1%) were ex-smokers, while 39.8% reported dual use (using both conventional and e-cigarettes). 5 , 30 Adults aged 35–44 years were most likely to be current users (9.5%), followed by 45–54-year-olds (9.3%), 25–34 year-olds (7.8%), 18–24-year-olds (4.3%) and over-55-year-olds (5.6%). 31 In the EU, the prevalence of ever-use of e-cigarettes increased from 7.2% in 2012 to 11.6% in 2014 32 to 14.6% in 2017. 33 In 2017, 1.8% of adults were current regular e-cigarette users; the UK (4.7%) and France (3.7%) had the highest prevalence, while Italy (0.2%) and Bulgaria (0.2%) had the lowest. Almost two in five (37.9%) current smokers reported having tried e-cigarettes, which was higher than for ex-smokers (15.7%) and never smokers (2.7%). 34 In Poland, a 2019 study found 4.0% of participants had used e-cigarettes and 1.4% were current e-cigarette users. 35 In Germany in 2015, 2.9% of 18–64-year-olds reported having used e-cigarettes in the past month. 36
In New Zealand in 2016, ever use and current use of e-cigarettes were estimated to be 17% and 2% respectively. 37 In 2014, prevalence was highest among current smokers (49.9% ever-use and 4.0% current use), followed by ex-smokers (8.4% ever-use and 0.1% current use) and never smokers (3.4% ever-use and 0.1% current use). 38
In Malaysia in 2016, ever-use and current use of e-cigarettes were 11.9% and 3.2% respectively. Prevalence was highest among current smokers (34.3% ever-use, 10% current use), followed by ex-smokers (15.4% ever-use, 4.3% current use) and never smokers (3.1% ever-use and 0.6% current use). 39 E-cigarette use is more common in smokers who are young (18–44-year-old), male, single, students and living in urban areas. 40 , 41
In Korea, between 2013 and 2016, ever use and current use of e-cigarettes were 7.7% and 2.0% respectively. Prevalence was highest among current smokers (28.8% ever use, 8% current use), followed by ex-smokers (7.3% ever use, 1.5% current use) and never smokers (0.4% ever use and 0.1% current use). E-cigarette use was also more common in younger age groups, males and lower socioeconomic groups. 42
In China, a series of city-wide surveys in 2013–14 found 2.9% of respondents had used e-cigarettes and 0.8% were current users, most of whom were tobacco smokers (93.0%). 43 Another study of young adults (19–29 years) in China found 24.5% were e-cigarette users, though only 2.3% were frequent users. 44
Results from the 2016 ITC survey of Australia, England, US and Canada showed that participants with alcohol problems and depression were more likely to be e-cigarette users. 45 Other predictors of e-cigarette use include lifetime mental health conditions and psychological distress. 46 47 Another study showed e-cigarette users had on average higher state-trait anxiety as well as more open and neurotic personality traits compared to a non-user sample. 48 A study of young adults in the US found marijuana and alcohol use, both dually and exclusively, increased likelihood of current e-cigarette use. 49 E-cigarette users are more likely than non-users to engage in high risk behaviour such as the use of non- prescribed pain-killers, sedatives, tranquilizers and Ritalin. 50 Another study of young adults found childhood maltreatment was associated with e-cigarette use. 51 A large US study in 2014-16 found that while smoking is associated with lower socioeconomic status, e-cigarette use showed no association with income or education level. 52 Another study in the US found that white smokers with higher-incomes were more likely to exclusively use e-cigarettes than African American, Hispanic and low-income smokers, who tended to view tobacco smoking as less harmful and more socially acceptable. 53 A survey of young adults in France found that lifetime e-cigarette use was associated with low socioeconomic status, smoking, positive perception of e-cigarettes, asthma, and overweight/obesity, while current use was only associated with smoking and positive perceptions. 54 In Germany in 2015, users were more likely young, male and tobacco smokers. 55
18B.3.3 International trends in use among teenagers
Awareness of and experimentation by children and adolescents are growing in some countries, and it is of note that experimentation with e-cigarettes may be more common among non-smoking youth than among non-smoking adults. A review of e-cigarette use among adolescents found that use was more likely among those who were male, older, had a higher amount of pocket money, and had more tobacco smoking-related characteristics, such as regular and heavier smoking, and having peers who smoke. 56 Another study found adolescents who experience depressive symptoms are more likely to use e-cigarettes and even more so if they have a parents with depression. 57 In Korea and Canada studies found use of e-cigarettes was associated with illicit drugs and alcohol use. 58 , 59
Multiple studies have found the majority of teenage e-cigarette users use flavoured e-liquids/refills, fruit flavours being the most common. 60-62 In the US, past month flavoured e-cigarette use was highest in teenage e-cigarette users (97%), followed by young adult users (96.8%) and adult users (81.2%). 63
National data from the US show that in 2019, e-cigarettes were the most commonly used tobacco product among high school (27.5%) and middle school (10.5%) students. In 2019, 21% of e-cigarette users in high school and 9% of users in middle school reported using e-cigarettes daily. There was a nonlinear increase in e-cigarette use between 2011 and 2019 among middle school (0.6% to 10.5%) and high school students (1.5% to 27.5%). 64-68 Another nationally representative survey in 2019 found even higher rates of current electronic vapor product use among high school students (32.7%), though lower rates of daily use (7.2%) and a frequent use rate of 10.7%. These rates were more than double that of 2017, in which 13.2% of high school student were current users, 2.4% were daily users and 3.3% were frequent users. 69
Though in 2019 overall tobacco use rose to 31.2% of high school students and 12.5% of middle school students due to the increase in e-cigarette use. 64 An analysis of trends from 2011 to 2015 found that in all years, e-cigarette use was associated with use of cigarettes and other tobacco products; however, over time, past month e-cigarette users increasingly comprised those who had never used other tobacco products (from 0.1% in 2011 to 1.8% in 2015 for girls and 0.2% to 2.9% for boys). 70
In the US, use of JUUL branded e-cigarettes (see Section 18B.1) is particularly high among adolescents. In 2018 an estimated 7.6% of 15–17-year-olds and 1.5% of 13–14-year-olds had ever-used a JUUL e-cigarette. 71 In 2019, among current e-cigarette users, an estimated 59.1% of US high school students and 54.1% of middle school students reported JUUL as their usual e-cigarette brand in the past 30 days. 64 A two-wave study found a pattern of graduation in the type of e-cigarettes system used. Most adolescents who used non-rechargeable or refillable in the first wave, progressed to using rechargeable and refillable e-cigarette systems by the second wave. 72
In Canada in 2017, 6.3% of 15–19-year-olds reported having used an e-cigarette in the past 30 days, unchanged from 6.3% in 2015 and greater than the 2.6% in 2013. In 2016-17, 5.4% of Canadian students in grades 7–9 reported having used an e-cigarette in the past 30 days, compared to 3.9% in 2014–15. 73 Data from various surveys of 11–16-year-olds across the UK show that for 2015-16, ever-use of e-cigarettes ranged from 7% to 18%, and regular (at least weekly) use ranged from 1% to 3%. Among never smokers, ever-use ranged from 4% to 10%, with regular use between 0.1% and 0.5%. Among regular smokers, ever-use ranged from 67% to 92% and regular use 7% to 38%. One survey indicated an increase in the prevalence of ever use of e-cigarettes from 7% (2016) to 11% (2017), but the prevalence of regular remained stable at 1%. 74 In 2019 in Great Britain, 2% of 11–18-year-olds reported using e-cigarettes at least weekly, 3% reported using them once a month or less, and 10% had tried them just once or twice. Use increased with age; 8.5%% of 11–15-year-olds and 26.7% of 16–18-year-olds reported having tried an e-cigarette, and at least weekly use increased from 1.1% for 11–15-year-olds to 2.5% of 16–18-year-olds. Six per cent of never smokers reported ever use of e-cigarettes, compared with 46% of former smokers and 76% of current smokers. 75 , 76 Relative to the US and Canada, little increase has been seen between 2017 and 2018 in England. 77
In New Zealand, ever-use of e-cigarettes among teenagers is steadily increasing from 33.3% in 2018 to 37.3% in 2019 and daily use has increased from 1.8% in 2018 to 3.1% in 2019. 78 , 79 A study in Switzerland found that in 2012, 43% of adolescents had ever tried e-cigarettes, with 19% of them being experimenters and 24% users (i.e., used several times or regularly). 80 Awareness and ever-use of e-cigarettes increased significantly among Finnish adolescents from 2013 to 2015; ever-use increased from 17.4% to 25%. 81 In Poland, ever-use and current use of e-cigarettes in teenagers aged 15–19 increased from 16% and 5.5% respectively in 2010–11, to 62% and 30% in 2013–14. Current use of e-cigarettes (use in past 30 days) in teenagers aged 15–19 increased from 5.5% in 2010–11 to 29.9% in 2013–14. 82 Ever use among 15-year-olds in Greece in 2014 was 16.6%, and most of this was experimentation (0.5% reported current e-cigarette use). 83 In Serbia, 6.2% of 13–15-year-olds had recently used e-cigarettes according to a 2017 survey. 84 In Italy the estimated percentage of 13–15-year-olds using e-cigarettes has increased from 7.4% in 2014 to 17.5% in 2018 while the prevalence of tobacco cigarette use has remained about 20%. 85 In 13 Eastern European urban areas, one-third of adolescents had used e-cigarettes, and one in five had used e-cigarettes three or more times; 2.6% of never cigarette smokers had used e-cigarettes at least three times. 86 In 2017, 52% of French 17-year-olds had tried e-cigarettes, and 8% of those who had recently used e-cigarettes had never tried tobacco cigarettes. 87 Over one-quarter (28.6%) of Russian adolescents reported having ever used an e-cigarette in 2015, and 2.2% reported past-month use. Ever smokers were substantially more likely to have tried e-cigarettes. 88
A survey of middle school students in China in 2013–14 found that prevalence of e-cigarette use was 1.2% and prevalence of e-cigarette awareness was 45.0%. 89 A 2017 study of middle and high school students the Zhejiang province, found 2.15% had used e-cigarettes in the past month. 90 In South Korea in 2015, the prevalence of e-cigarette ever and current (past 30 days) use among adolescents was 10.1% and 3.9%, respectively. 91 In Malaysia, a 2019 study of adolescents found 9% had used e-cigarettes in the past month. 92 In Indonesia, a 2018 study of high-school students found 32.2% had used e-cigarettes and 11.8% were current e-cigarette users. 93
Relevant news and research
For recent news items and research on this topic, click here. ( Last updated October 2020)
1. Australian Institute of Health and Welfare. Data tables: National Drug Strategy Household Survey 2019 - 2. Tobacco smoking chapter, Supplementary data tables. Canberra: AIHW, 2020. Available from: https://www.aihw.gov.au/reports/illicit-use-of-drugs/national-drug-strategy-household-survey-2019/data.
2. Australian Institute of Health and Welfare. National Drug Strategy Household Survey 2016 key findings. 2017. Available from: https://www.aihw.gov.au/reports/illicit-use-of-drugs/ndshs-2016-key-findings/contents/summary
3. Centers for Disease Control and Prevention. QuickStats: Cigarette Smoking Status Among Current Adult E-cigarette Users, by Age Group—National Health Interview Survey, United States, 2015. Morbidity and Mortality Weekly Report, 2016; 65:1177. Available from: http://dx.doi.org/10.15585/mmwr.mm6542a7
4. Dai H and Leventhal AM. Prevalence of e-Cigarette Use Among Adults in the United States, 2014-2018. The Journal of the American Medical Association, 2019:1824–1827. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31524940
5. Action on Smoking and Health. Use of e-cigarettes (vapourisers) among adults in Great Britain. 2018. Available from: http://ash.org.uk/download/use-of-e-cigarettes-among-adults-in-great-britain-2017/
6. Centre for Behavioural Research in Cancer. Analysis of Australian Institute of Health and Welfare National Drug Strategy Household Survey, 2013 [computer file; Australian Data Archive, The Australian National University]. 2016.
7. Chan G, Leung J, Gartner C, Yong HH, Borland R, et al. Correlates of electronic cigarette use in the general population and among smokers in Australia - Findings from a nationally representative survey. Addictive Behaviors, 2019; 95:6–10. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30784874
8. Jongenelis MI, Brennan E, Slevin T, Kameron C, Jardine E, et al. Factors associated with intentions to use e-cigarettes among Australian young adult non-smokers. Drug and Alcohol Review, 2019; 38(5):579–587. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31317596
9. Twyman L, Watts C, Chapman K, and Walsberger SC. Electronic cigarette use in New South Wales, Australia: reasons for use, place of purchase and use in enclosed and outdoor places. Australian and New Zealand Journal of Public Health 2018:491–496. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30152006
10. Guerin N and White V. Secondary school students’ use of tobacco, alcohol and other drugs in 2017: Second Edition. Cancer Council Victoria, 2020. Available from: https://www.health.gov.au/resources/publications/secondary-school-students-use-of-tobacco-alcohol-and-other-drugs-in-2017.
11. Williams T and White V. What Factors are Associated with Electronic Cigarette, Shisha-Tobacco and Conventional Cigarette Use? Findings from a Cross-Sectional Survey of Australian Adolescents? Substance Use & Misuse, 2018:1–11. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29336657
12. Thomas DP, Lusis N, Van der Sterren AE, and Borland R. Electronic Cigarette Use and Understanding Among a National Sample of Australian Aboriginal and Torres Strait Islander Smokers. Nicotine & Tobacco Research, 2019; 21(10):1434–1440. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30053109
13. Gravely S, Fong GT, Cummings KM, Yan M, Quah AC, et al. Awareness, trial, and current use of electronic cigarettes in 10 countries: Findings from the ITC project. International Journal of Environmental Research and Public Health, 2014; 11(11):11691–704. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25421063
14. Gravely S, Fong GT, Cummings KM, Yan M, Quah AC, et al. Correction: Gravely, S., et al. Awareness, Trial, and Current Use of Electronic Cigarettes in 10 Countries: Findings from the ITC Project. Int. J. Environ. Res. Public Health 2014, 11, 11691-11704. International Journal of Environmental Research and Public Health, 2015; 12(5):4631–7. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25922990
15. Lee C, Yong HH, Borland R, McNeill A, and Hitchman SC. Acceptance and patterns of personal vaporizer use in Australia and the United Kingdom: Results from the International Tobacco Control survey. Drug and Alcohol Dependence, 2018; 185:142–148. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29448147
16. Borland R, Murray K, Gravely S, Fong GT, Thompson ME, et al. A new classification system for describing concurrent use of nicotine vaping products alongside cigarettes (so-called 'dual use'): findings from the ITC-4 Country Smoking and Vaping wave 1 Survey. Addiction, 2019; 114 Suppl 1:24–34. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30702175
17. O'Connor RJ, Fix BV, McNeill A, Goniewicz ML, Bansal-Travers M, et al. Characteristics of nicotine vaping products used by participants in the 2016 ITC Four Country Smoking and Vaping Survey. Addiction, 2019:15–23. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30701622
18. Li J, Newcombe R, and Walton D. The prevalence, correlates and reasons for using electronic cigarettes among New Zealand adults. Addictive Behaviors, 2015; 45:245–51. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25744712
19. Reid J, Hammond D, Rynard V, Madill C, and Burkhalter R. Tobacco Use in Canada: Patterns and Trends 2017 Edition. 2017. Available from: https://uwaterloo.ca/tobacco-use-canada/sites/ca.tobacco-use-canada/files/uploads/files/2017_tobaccouseincanada_final_0.pdf
20. Centers for Disease Control and Prevention. QuickStats: Percentage of Adults Who Ever Used an E-cigarette and Percentage Who Currently Use E-cigarettes, by Age Group—National Health Interview Survey, United States, 2016. Morbidity and Mortality Weekly Report, 2017; 66:892. Available from: http://dx.doi.org/10.15585/mmwr.mm6633a6
21. Centres for Disease Control and Prevention. QuickStats: Percentage of Adults Aged ≥18 Years Who Currently Use E-Cigarettes, by Sex and Age Group — National Health Interview Survey, 2016. Morbidity and Mortality Weekly Report, 2018; 66:1412. Available from: https://www.cdc.gov/mmwr/volumes/66/wr/mm665152a7.htm?s_cid=mm665152a7_w
22. QuickStats: Age-Adjusted Percentage* of Adults Who Had Ever Used an E-cigarette,(dagger) by Race and Ethnicity - National Health Interview Survey, United States, 2014 and 2018( section sign). Morbidity and Mortality Weekly Report, 2019; 68(47):1102. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31774739
23. Mirbolouk M, Charkhchi P, Orimoloye OA, and et al. E-cigarette use without a history of combustible cigarette smoking among US adults: Behavioral risk factor surveillance system, 2016. Annals of Internal Medicine, 2018:76–79. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30304466
24. Dai H and Leventhal AM. Prevalence of e-Cigarette Use Among Adults in the United States, 2014-2018. JAMA, 2019. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31524940
25. QuickStats: Percentage of Adults Aged 18-24 Years Who Currently Smoke Cigarettes* or Who Currently Use Electronic Cigarettes,(dagger) by Year - National Health Interview Survey, United States, 2014-2018( section sign). Morbidity and Mortality Weekly Report, 2019; 68(39):870. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31581167
26. Parker MA and Villanti AC. Patterns and Frequency of Current e-Cigarette Use in United States Adults. Substance Use & Misuse, 2019:1–7. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31226905
27. Hu SS, Homa DM, Wang T, Gomez Y, Walton K, et al. State-Specific Patterns of Cigarette Smoking, Smokeless Tobacco Use, and E-Cigarette Use Among Adults - United States, 2016. Preventing Chronic Disease, 2019; 16:E17. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30730828
28. Zavala-Arciniega L, Rodriguez-Andrade MA, Reynales-Shigematsu LM, Lozano P, Arillo-Santillan E, et al. Patterns of awareness and use of electronic cigarettes in Mexico, a middle-income country that bans them: Results from a 2016 national survey. Preventive Medicine, 2018:211–218. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30261244
29. Bertoni N, Szklo A, Boni R, Coutinho C, Vasconcellos M, et al. Electronic cigarettes and narghile users in Brazil: Do they differ from cigarettes smokers? Addictive Behaviors, 2019; 98:106007. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31247536
30. No authors listed. Fact sheet: Use of e-cigarettes among adults in Great Britain. Action on Smoking and Health, 2019. Available from: http://ash.org.uk/wp-content/uploads/2019/09/Use-of-e-cigarettes-among-adults-2019.pdf.
31. Action on Smoking and Health. Use of e-cigarettes (vaporisers) among adults in Great Britain. ASH, 2019. Available from: https://ash.org.uk/wp-content/uploads/2019/09/Use-of-e-cigarettes-among-adults-2019.pdf.
32. Filippidis FT, Laverty AA, Gerovasili V, and Vardavas CI. Two-year trends and predictors of e-cigarette use in 27 European Union member states. Tobacco Control, 2017; 26(1):98–104. Available from: https://www.ncbi.nlm.nih.gov/pubmed/27220621
33. Laverty AA, Filippidis FT, and Vardavas CI. Patterns, trends and determinants of e-cigarette use in 28 European Union Member States 2014-2017. Preventive Medicine, 2018:13–18. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30144487
34. Laverty AA, Filippidis FT, and Vardavas CI. Patterns, trends and determinants of e-cigarette use in 28 European Union Member States 2014-2017. Prev Med, 2018. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30144487
35. Pinkas J, Kaleta D, Zgliczynski WS, Lusawa A, Wrzesniewska-Wal I, et al. The Prevalence of Tobacco and E-Cigarette Use in Poland: A 2019 Nationwide Cross-Sectional Survey. International Journal of Environmental Research and Public Health, 2019; 16(23):4820. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31801221
36. Atzendorf J, de Matos EG, Kroger C, Kraus L, and Piontek D. [The use of E-Cigarettes in the German Population: Results of the Epidemiological Survey of Substance Abuse 2015]. Gesundheitswesen, 2019; 81(2):137–143. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29486498
37. Oakly A, Edwards R, and Martin G. Prevalence of e-cigarette use from a nationally representative sample in New Zealand. Addictive Behaviors, 2019; 98:106024. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31233951
38. Li J, Newcombe R, and Walton D. The prevalence, correlates and reasons for using electronic cigarettes among New Zealand adults. Addict Behav, 2015; 45:245–51. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25744712
39. Ab Rahman J, Mohd Yusoff MF, Nik Mohamed MH, Mahadir Naidu B, Lim KH, et al. The Prevalence of E-Cigarette Use Among Adults in Malaysia. Asia-Pacific Journal of Public Health, 2019; 31(7_suppl):9S–21S. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30880403
40. Ho BK, Mohamad Haniki NM, Jamalludin AR, Samsul D, Mira K, et al. Prevalence and characteristics of e-cigarette users among Malaysian current and ex-smokers. Malaysian Family Physician, 2019; 14(2):10–17. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31827730
41. Puteh SEW, Manap RA, Hassan TM, Ahmad IS, Idris IB, et al. The use of e-cigarettes among university students in Malaysia. Tobacco Induced Diseases 2018; 16:57. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31516454
42. Chang Y, Cho S, Kim I, and Khang YH. Socioeconomic Inequalities in e-Cigarette Use in Korea: Comparison with Inequalities in Conventional Cigarette Use Using Two National Surveys. International Journal of Environmental Research and Public Health, 2019; 16(22):4458. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31766232
43. Zhao L, Mbulo L, Palipudi K, Wang J, and King B. Awareness and use of e-cigarettes among urban residents in China. Tobacco Induced Diseases 2019; 17:53. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31582942
44. Wang X, Zhang X, Xu X, and Gao Y. Perceptions and use of electronic cigarettes among young adults in China. Tobacco Induced Diseases 2019; 17:17. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31582928
45. Li L, Borland R, O'Connor RJ, Fong GT, McNeill A, et al. How Are Self-Reported Physical and Mental Health Conditions Related to Vaping Activities among Smokers and Quitters: Findings from the ITC Four Country Smoking and Vaping Wave 1 Survey. International Journal of Environmental Research and Public Health, 2019; 16(8):1412. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31010185
46. Spears CA, Jones DM, Weaver SR, Yang B, Pechacek TF, et al. Electronic nicotine delivery system (ENDS) use in relation to mental health conditions, past-month serious psychological distress and cigarette smoking status, 2017. Addiction, 2018:315–325. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30291763
47. Bianco CL. Rates of electronic cigarette use among adults with a chronic mental illness. Addictive Behaviors, 2019; 89:1–4. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30237110
48. Grzywacz A, Suchanecka A, Chmielowiec J, Chmielowiec K, Szumilas K, et al. Personality Traits or Genetic Determinants-Which Strongly Influences E-Cigarette Users? International Journal of Environmental Research and Public Health, 2020; 17(1):365. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31948125
49. Bluestein M, Kelder S, Perry CL, and Perez A. Exploring associations between the use of alcohol and marijuana with e-cigarette use in a U.S.A. nationally representative sample of young adults. International Journal of Health Sciences, 2019; 13(1):30–39. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30842716
50. Bentivegna K, Atuegwu NC, Oncken C, Mead EL, Perez MF, et al. E-cigarette Use Is Associated with Non-prescribed Medication Use in Adults: Results from the PATH Survey. Journal of General Internal Medicine, 2019; 34(10):1995–1997. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31190256
51. Shin SH, Conley D, Ksinan Jiskrova G, and Wills TA. Adverse Childhood Experiences and E-Cigarette Use During Young Adulthood. The American Journal on Addictions, 2019:303–310. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31069879
52. Friedman AS and Horn SJL. Socioeconomic Disparities in Electronic Cigarette Use and Transitions from Smoking. Nicotine & Tobacco Research, 2019; 21(10):1363–1370. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29917124
53. Harlow AF, Stokes A, and Brooks DR. Socioeconomic and Racial/Ethnic Differences in E-Cigarette Uptake Among Cigarette Smokers: Longitudinal Analysis of the Population Assessment of Tobacco and Health (PATH) Study. Nicotine & Tobacco Research, 2019; 21(10):1385–1393. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29986109
54. Aljandaleh H, Bolze C, El-Khoury Lesueur F, Melchior M, and Mary-Krause M. Factors Associated with Electronic Cigarette Use among Young Adults: The French "Trajectoires EpideMiologiques en POpulation" (TEMPO) Cohort Study. Substance Use & Misuse, 2020; 55(6):964–972. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31997695
55. Atzendorf J, de Matos EG, Kroger C, Kraus L, and Piontek D. [The use of E-Cigarettes in the German Population: Results of the Epidemiological Survey of Substance Abuse 2015]. Gesundheitswesen, 2018. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29486498
56. Perikleous EP, Steiropoulos P, Paraskakis E, Constantinidis TC, and Nena E. E-Cigarette Use Among Adolescents: An Overview of the Literature and Future Perspectives. Frontiers in Public Health 2018; 6:86. Available from: https://www.ncbi.nlm.nih.gov/pubmed/29632856
57. Cho BY. Parent's Depression as a Moderator of the Association Between Offspring's Depressive Symptoms and Use of Combustible Cigarettes and Electronic Vapor Products. The Journal of Behavioral Health Services & Research, 2019; 46(4):648–655. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30868451
58. Lee Y and Lee KS. Association of alcohol and drug use with use of electronic cigarettes and heat-not-burn tobacco products among Korean adolescents. PLoS One, 2019; 14(7):e0220241. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31365564
59. Mehra VM, Keethakumar A, Bohr YM, Abdullah P, and Tamim H. The association between alcohol, marijuana, illegal drug use and current use of E-cigarette among youth and young adults in Canada: results from Canadian Tobacco, Alcohol and Drugs Survey 2017. BMC Public Health, 2019; 19(1):1208. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31477067
60. Schneller LM, Bansal-Travers M, Goniewicz ML, McIntosh S, Ossip D, et al. Use of flavored electronic cigarette refill liquids among adults and youth in the US-Results from Wave 2 of the Population Assessment of Tobacco and Health Study (2014-2015). PLoS One, 2018; 13(8):e0202744. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30138412
61. Cullen KA, Gentzke AS, Sawdey MD, Chang JT, Anic GM, et al. e-Cigarette Use Among Youth in the United States, 2019. The Journal of the American Medical Association, 2019. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31688912
62. Goldenson NI, Leventhal AM, Simpson KA, and Barrington-Trimis JL. A Review of the Use and Appeal of Flavored Electronic Cigarettes. Current Addiction Reports 2019; 6(2):98–113. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31453046
63. Rostron BL, Cheng YC, Gardner LD, and Ambrose BK. Prevalence and Reasons for Use of Flavored Cigars and ENDS among US Youth and Adults: Estimates from Wave 4 of the PATH Study, 2016-2017. American Journal of Health Behavior 2020; 44(1):76–81. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31783934
64. Cullen KA, Gentzke AS, Sawdey MD, Chang JT, Anic GM, et al. e-Cigarette Use Among Youth in the United States, 2019. JAMA, 2019. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31688912
65. Cullen KA, Ambrose BK, Gentzke AS, Apelberg BJ, Jamal A, et al. Notes from the Field: Use of Electronic Cigarettes and Any Tobacco Product Among Middle and High School Students - United States, 2011-2018. Morbidity and Mortality Weekly Report, 2018; 67(45):1276–1277. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30439875
66. Wang T, Gentzke A, Sharapova S, Cullen K, Ambrose B, et al. Tobacco Product Use Among Middle and High School Students — United States, 2011–2017. Morbidity and Mortality Weekly Report, 2018; 67:629–633. Available from: http://dx.doi.org/10.15585/mmwr.mm6722a3
67. Cullen KA, Ambrose BK, Gentzke AS, Apelberg BJ, Jamal A, et al. Notes from the Field: Use of Electronic Cigarettes and Any Tobacco Product Among Middle and High School Students - United States, 2011-2018. MMWR Morb Mortal Wkly Rep, 2018; 67(45):1276-1277. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30439875
68. Miech R, Schulenberg J, Johnston L, Bachman J, O'Malley P, et al. National Adolescent Drug Trends in 2018. Monitoring the Future, 17/12/2018 2018. Available from: http://monitoringthefuture.org/data/18data.html#2018data-drugs
69. Centres for Disease Control and Prevention. Trends in the Prevalence of Tobacco Use National YRBS: 1991—2019, in Youth Risk Behavior Surveillance System (YRBSS)2020. Available from: https://www.cdc.gov/healthyyouth/data/yrbs/index.htm.
70. Chaffee BW, Couch ET, and Gansky SA. Trends in characteristics and multi-product use among adolescents who use electronic cigarettes, United States 2011-2015. PLoS One, 2017; 12(5):e0177073. Available from: https://www.ncbi.nlm.nih.gov/pubmed/28475634
71. McKeganey N and Russell C. Prevalence of Awareness and Use of JUUL E-cigarettes in a National Probability Sample of Adolescents in the United States. American Journal of Health Behavior 2019; 43(3):591–605. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31046889
72. McMillen R, Tanski S, Wilson K, Klein JD, and Winickoff JP. Adolescent Use of Different E-cigarette Products. Pediatrics, 2018. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30201626
73. Reid J, Hammond D, Tariq U, Burkhalter R, Rynard V, et al. Tobacco Use in Canada: Patterns and Trends, 2019 Edition. Waterloo, ON: Propel Centre for Population Health Impact, University of Waterloo., 2019. Available from: https://uwaterloo.ca/tobacco-use-canada/sites/ca.tobacco-use-canada/files/uploads/files/tobacco_use_in_canada_2019.pdf.
74. Bauld L, MacKintosh A, Eastwood B, Ford A, Moore G, et al. Young People’s Use of E-Cigarettes across the United Kingdom: Findings from Five Surveys 2015–2017. International Journal of Environmental Research and Public Health, 2017; 14(9):973. Available from: http://www.mdpi.com/1660-4601/14/9/973
75. Action on Smoking and Health. Use of e-cigarettes among young people in Great Britain. 2018. Available from: http://ash.org.uk/download/use-of-electronic-cigarettes-among-children-in-great-britain/
76. Action on Smoking and Health. Use of e-cigarettes among young people in Great Britain. Fact Sheet, 2018. Available from: http://ash.org.uk/download/use-of-electronic-cigarettes-among-children-in-great-britain/
77. Hammond D, Reid JL, Rynard VL, Fong GT, Cummings KM, et al. Prevalence of vaping and smoking among adolescents in Canada, England, and the United States: repeat national cross sectional surveys. The BMJ, 2019; 365:l2219. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31221636
78. Action for Smokfree 2025. 2018 ASH Year 10 Snapshot; E-cigarettes and Vaping. ASH, 2019. Available from: https://d3n8a8pro7vhmx.cloudfront.net/ashnz/pages/70/attachments/original/1554281098/2018_ASH_Y10_Snapshot_E-cigs_FINAL.pdf?1554281098.
79. Walker N, Parag V, Wong SF, Youdan B, Broughton B, et al. Use of e-cigarettes and smoked tobacco in youth aged 14-15 years in New Zealand: findings from repeated cross-sectional studies (2014-19). Lancet Public Health, 2020:e204–e212. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31981489
80. Suris JC, Berchtold A, and Akre C. Reasons to use e-cigarettes and associations with other substances among adolescents in Switzerland. Drug and Alcohol Dependence, 2015; 153:140–4. Available from: https://www.ncbi.nlm.nih.gov/pubmed/26077606
81. Kinnunen JM, Ollila H, Lindfors PL, and Rimpela AH. Changes in Electronic Cigarette Use from 2013 to 2015 and Reasons for Use among Finnish Adolescents. International Journal of Environmental Research and Public Health, 2016; 13(11):1114. Available from: https://www.ncbi.nlm.nih.gov/pubmed/27834885
82. Goniewicz ML, Gawron M, Nadolska J, Balwicki L, and Sobczak A. Rise in electronic cigarette use among adolescents in Poland. Journal of Adolescent Health, 2014; 55(5):713–5. Available from: https://www.ncbi.nlm.nih.gov/pubmed/25344033
83. Fotiou A, Kanavou E, Stavrou M, Richardson C, and Kokkevi A. Prevalence and correlates of electronic cigarette use among adolescents in Greece: a preliminary cross-sectional analysis of nationwide survey data. Addictive Behaviors, 2015; 51:88–92. Available from: https://www.ncbi.nlm.nih.gov/pubmed/26240943
84. Kilibarda B, Vukovic D, and Krstev S. Prevalence and correlates of concurrent use of cigarettes, electronic cigarettes, and waterpipes among Serbian youth. Tobacco Induced Diseases 2019; 17:66. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31582955
85. Gorini G, Gallus S, Carreras G, De Mei B, Masocco M, et al. Prevalence of tobacco smoking and electronic cigarette use among adolescents in Italy: Global Youth Tobacco Surveys (GYTS), 2010, 2014, 2018. Preventive Medicine, 2020; 131:105903. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31812559
86. Kristjansson AL, Mann MJ, Sigfusson J, Sarbu EA, Grubliauskiene J, et al. Prevalence of e-cigarette use among adolescents in 13 Eastern European towns and cities. Public Health, 2017; 147:66–68. Available from: http://www.ncbi.nlm.nih.gov/pubmed/28404498
87. Chyderiotis S, Spilka S, and Beck F. Use of electronic cigarette in France among adolescents aged 17: Results from the ESCAPAD 2017 survey. Bull Cancer, 2019; 106(12):1132–1143. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31732122
88. Kong G, Idrisov B, Galimov A, Masagutov R, and Sussman S. Electronic Cigarette Use Among Adolescents in the Russian Federation. Substance Use & Misuse, 2016:1–8. Available from: http://www.ncbi.nlm.nih.gov/pubmed/27767370
89. Xiao L, Parascandola M, Wang C, and Jiang Y. Perception and Current Use of E-cigarettes Among Youth in China. Nicotine & Tobacco Research, 2018:1401–1407. Available from: https://www.ncbi.nlm.nih.gov/pubmed/30053201
90. Wang M, Hu RY, Pan J, Wang H, Yu M, et al. Awareness, current use of electronic cigarettes and associated smoking factors in Zhejiang Chinese adolescents. PLoS One, 2019; 14(10):e0224033. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31634360
91. Lee JA, Lee S, and Cho H-J. The Relation between Frequency of E-Cigarette Use and Frequency and Intensity of Cigarette Smoking among South Korean Adolescents. International Journal of Environmental Research and Public Health, 2017; 14(3):305. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5369141/
92. Robert Lourdes TG, Abd Hamid HA, Mohd Yusoff MF, Rodzlan Hasani WS, Mat Rifin H, et al. Factors Associated With E-Cigarette Usage and the Reasons for Initiation Among Malaysian Adolescents. Asia-Pacific Journal of Public Health, 2019:1010539519870663. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31522514
93. Bigwanto M, Nurmansyah MI, Orlan E, Farradika Y, and Purnama TB. Determinants of e-cigarette use among a sample of high school students in Jakarta, Indonesia. International Journal of Adolescent Medicine and Health 2019. Available from: https://www.ncbi.nlm.nih.gov/pubmed/31800392