Estimates suggest that among children who try smoking, between one third and one half are likely to become regular smokers within two to three years. However, young people are now more likely to experiment with e-cigarettes than they are with tobacco cigarettes. For example, a 2014 study found that 22% of children aged 11-15 in England had experimented with e-cigarettes, compared to 18% for tobacco cigarettes.

There is concern that the increasing exposure of children to e-cigarette adverts could be contributing to high rates of experimentation; in the US, adolescents' exposure to e-cigarette adverts on TV more than trebled between 2011 to 2013. E-cigarette brands often market themselves as helping people quit smoking and as healthier and cheaper alternatives to tobacco cigarettes.

In this study from researchers at the Behaviour and Health Research Unit, University of Cambridge, and the University of North Carolina Gillings School of Global Public Health, and published today in the journal Tobacco Control, more than 400 English children aged 11-16 who had never smoked or 'vaped' previously were recruited and randomly allocated to one of three groups. One group was shown ten adverts that depicted e-cigarettes as glamorous, a second group was shown ten adverts that portrayed them as healthy, and a third control group was shown no adverts.

The children were then asked a series of questions aimed at determining their attitudes towards smoking and vaping. Children shown the adverts were no more or less likely than the control group to perceive tobacco smoking as appealing and all three groups understood that smoking more than ten cigarettes a day was harmful. However, both groups of children exposed to the e-cigarette adverts, both healthy and glamorous, were less likely to believe that smoking one or two tobacco cigarettes occasionally was harmful.

Dr Milica Vasiljevic from the Department of Public Health and Primary Care at the University of Cambridge says: "While we can be optimistic that the adverts don't seem to make tobacco smoking more appealing to young people, they do appear to make occasional smoking seem less harmful. This is worrying, as we know that even occasional tobacco smoking is bad for your health, and young people who smoke occasionally believe they are somehow immune to its effects and do not feel the need to quit."

The group of children that were shown adverts depicting e-cigarettes as glamorous also believed e-cigarette vaping to be more prevalent than did the other two groups.

Professor Theresa Marteau, Director of the Behaviour and Health Research Unit and a Fellow of Christ's College, University of Cambridge, adds: "E-cigarette marketing across Europe is regulated under the new EU Tobacco Products Directive, which came into effect on the 20th May this year. The Directive limits the exposure of children to TV and newspaper e-cigarette adverts. However, it does not cover advertising in the form of posters, leaflets, and adverts at point of sale, nor does it cover the content of marketing materials depicting e-cigarettes as glamorous or healthy. The findings from our study suggest these omissions could present a threat to the health of children."

The study was funded by the Department of Health.