The heated tobacco product iQOS is gaining more and more popularity worldwide, due to the industry claims of reduced toxicity. However, a detailed chemical characterization of iQOS emissions is lacking. Moreover, the impact of different smoking parameters on iQOS aerosol composition is still unknown. In this study, emissions from two conventional cigarettes (CCs) and nine iQOS HEETS were compared applying Health Canada Intense (HCI) and a more intense smoking regime.

Emissions were generated deploying HCI or the more intense smoking regime through a linear smoking machine (for CCs) and a linear vaping machine (for iQOS HEETS). HCI puff volume and puff duration were increased in the more intense smoking regime (puff volume from 55mL to 90mL and puff duration from 2s to 4s). All extraction and determination procedures were in accordance with WHO Tobacco Laboratory Network (TobLabNet) Standard Operating Procedures. Nicotine was measured by GC-FID, and tobacco-specific nitrosamines (TSNAs) were quantified with LC-MS.

iQOS HEETS delivered 38% lower nicotine and 95%-98% lower TSNAs levels compared with CCs. A clear topography effect was observed for all products: higher puff volume and puff duration caused a mean 22% increase in nicotine and a mean 21% increase in TSNAs delivery compared with HCI. Of note, emissions from the assessed iQOS HEETS showed significant differences in TSNAs levels: iQOS Amber, Sienna and Teak released the highest TSNAs concentrations, on average 26% higher than the other iQOS HEETS. 

The observed differences in TSNAs delivery from iQOS HEETS might resemble their specific product composition, thus distinct tobacco blends and flavoring additives. The more intense smoking parameters induced higher nicotine and TSNAs release in all the analyzed products. As the more intense smoking regime better mirrors real-life smoking behaviors, this study shows the inadequacy of HCI as standard smoking regime in laboratory settings.