Communicating the relative health risks of E-cigarettes: An online experimental study exploring the effects of a comparative health message versus the EU nicotine addiction warnings on smokers' and non-smokers' risk perceptions and behavioural intentions

Introduction: This study investigated the effects of the European Union Tobacco Products Directive [EU-TPD] Article 20 E-cigarette (EC) health warnings ("This product contains nicotine which is a highly addictive substance [It is not recommended for non-smokers.]") and a comparative harm message ("Use of this product is much less harmful than smoking" [COMP]) on smokers' and non-smokers' perceptions and behavioural intentions. Methods: 2495 UK residents (1283 smokers and 1212 non-smokers) self-reported perceived harm, addictiveness, EC effectiveness, social acceptability, and intentions to purchase and use EC, and in smokers, intentions to quit and intentions to use EC in future quit attempts. These were measured before and after exposure to EC images containing either the TPD, COMP, TPD + COMP or no message. Results: Non-smokers had higher harm, addictiveness and lower social acceptability perceptions. TPD presence increased, whilst COMP decreased, harm and addictiveness perceptions in both groups. For smokers only, harm perceptions were lower following exposure to COMP alone vs. no message. For non-smokers the TPD increased harm perceptions vs. no message. There were no effects on social acceptability, EC effectiveness or use intentions. In smokers only, purchase and quit intentions were higher following exposure to the COMP alone. Conclusion: TPD messages may be effective smoking prevention tools, although the COMP message was more effective in reducing harm perceptions and increasing use intentions in smokers. That COMP did not increase use intentions in non-smokers suggest that such exposures may potentially act as an effective harm reduction tool without resulting in increased uptake among non-smokers.