Since the invention of the electronic cigarette (e-cigarette) in 2003, there has been a shift in global nicotine markets. Instead of smoking tobacco cigarettes, people are increasingly turning to alternative nicotine products that avoid combustion, such as e-cigarettes, heated tobacco, and oral nicotine pouches. This thesis aims to understand (i) how and why people's choices of nicotine products have changed and (ii) what effects these changes have had on cigarette smoking prevalence and public health.
The first five chapters examine the changing patterns of nicotine use in Great Britain from 2016 to 2022. E-cigarettes remain the most popular alternative nicotine product, with few (<0.5%) adults using heated tobacco or nicotine pouches. However, smokers’ perceptions of the harmfulness of e-cigarettes deteriorated following the 2019 outbreak of lung injury linked to cannabis vaping. There were also changes in the types of e-cigarettes people used. Up to 2020, rechargeable e-cigarettes with refillable tanks were the most widely used device type, but the popularity of disposable e-cigarettes grew rapidly from 2021 onwards, especially among young adults. Despite this, the prevalence of any inhaled nicotine use remained relatively stable, both overall and among young adults.
The penultimate chapter reported results of a randomised trial. It found tentative evidence of the effectiveness of providing e-cigarettes alongside varenicline for smoking cessation. However, results were imprecise as the COVID-19 pandemic and recall of varenicline caused the trial to be stopped early. The final chapter reports a systematic review on heated tobacco, which found that switching from cigarettes to heated tobacco substantially lowers exposure to toxicants and carcinogens, but exposure may be higher compared with stopping all tobacco use. It found no randomised trials on heated tobacco for smoking cessation, but there was population-level evidence that declines in cigarette sales accelerated after heated tobacco was introduced in Japan
