Influence of machine-based puffing parameters on aerosol and smoke emissions from next generation nicotine inhalation products.

There is increasing diversity of nicotine inhalation products worldwide. Next Generation Products (NGP) such as e-cigarettes, have gained mass popularity, and there is increasing use of electrical and carbon-based Tobacco-Heating Products (e-THP and c-THP respectively). Recently, emission levels from these products have been compared to conventional cigarettes (CC); however, few formal laboratory testing standards exist, and inconsistent puffing parameters have been used. We investigated the impact of how a number of NGPs, including two e-cigarettes, a carbon-heated THP, and both pulse- and continuously-heated e-THPs, are puffed on the magnitude of their emissions, examining the influence of puff profile, volume, frequency and duration, in comparison to standard CCs. Our findings demonstrated that for each NGP choice of puffing parameters has a substantial impact on the magnitude of aerosol and smoke emissions, and that significant differences exist between different types of NGP. With e-cigarettes and pulse-heated e-THPs puff duration is the most important puffing parameter influencing yields. In contrast, for CCs, c-THPs and continuously-heated e-THPs, puff volume and puff frequency were the critical parameters. For e-cigarettes, there was no significant difference in emissions between rectangular and bell-shaped profiles. Our study has also shown that these different behaviours are a result of how heat-management within different NGPs, from heat-source to the nicotine- and aerosol-releasing substrates, is a vital mechanistic factor impacting aerosol generation. These findings point the need for detailed real-world e-cigarette and THP puffing topography data in order to identify the most appropriate puffing parameters for laboratory testing; our findings will help focus these studies on the most important parameters and can thereby support the future development of robust standardised NGP testing regimes.