It's not clear how much safer heated tobacco products (such as IQOS) are than traditional cigarettes. Most studies are sponsored by the tobacco industry.

https://www.sciencedirect.com/science/article/abs/pii/S07618...

> Of the 100 papers published in 2008–2018, 75 have authors affiliated or linked to TI [tobacco industry]. Emissions contain gases, droplets and solid particles, so are smokes. The main products are: THS2.2 (Iqos®) which heats mini-cigarettes at 340 °C, the THP1.0 (Glo®) which heats at 240 °C sticks delivering about half as much nicotine, Ploom® which uses reconstituted tobacco microcapsules heated at 180 °C. Under the experimental conditions, there is a reduction of toxic emissions and biological effects, but the expected risk reduction is not demonstrated. Symptoms related to passive smoking are described. The 4 epidemiological articles report that heated tobacco is used in 10 to 45% of cases by non-smokers and demonstrate the effectiveness of TI promotion campaigns. Thus, the THS2.2 is more a gateway to smoking (20%) than an exit door (11%); moreover, it is not expected risk reduction among the 69% who are mixed users.