Abstract
<title>Abstract</title> <p>Smoking is a cause of serious disease, with most harm arising from the combustion of tobacco and the inhalation of smoke. In response, there is growing interest in tobacco harm reduction strategies, particularly the substitution of smoking cigarettes with Next Generation Products, such as Electronic Vapour Products. However, concerns about their appeal to youth and non-smoking adults have prompted regulatory proposals to restrict or ban certain features of EVP, particularly non tobacco flavours. Such plans may influence the behaviour of current adult users, generating population level changes in smoking, vaping, and associated health outcomes. In this study, we predict the potential population health impact of a ban on non-tobacco flavoured EVP in the United Kingdom using a previously published dynamic population model projecting smoking and vaping prevalence to 2040. Historical prevalence data (2014–2022) were used to forecast future trends, and potential behavioural responses among current users of non-tobacco flavoured EVP were modelled across a range of scenarios. Mortality outcomes were estimated using excess relative risk assumptions ranging from 5% to 50% for EVP use relative to smoking. Results showed that future EVP prevalence and mortality outcomes were highly dependent on behavioural responses. Relapse to smoking was the dominant driver of harm, whereas switching or cessation produced substantially smaller effects. Overall, the results suggest that behavioural responses to a ban on non-tobacco flavoured EVP, especially the extent of smoking relapse, are likely to be important determinants of its population-level health impact.</p>