That's a good overview of papers in favour of vaping -- but note there's some conflict of interest concerns: > Conflict of interest statement: Riccardo Polosa.

That's a good overview of papers in favour of vaping -- but note there's some conflict of interest concerns: > Conflict of interest statement: Riccardo Polosa... has served as a consultant for Pfizer and Arbi Group Srl (Milano, Italy), the distributor of Categoria™ e-Cigarettes. > Konstantinos Farsalinos ... has received financial compensation from electronic cigarette companies for the studies’ cost. And some bold statements like this point that seems to be strongly contradicted by the chart at the top of the OP: > Regulatory authorities have expressed concern about EC use by youngsters or by never-smokers, with ECs becoming a gateway to smoking or becoming a new form of addiction. However, such concerns are unsubstantiated; research has shown that EC use by youngsters is virtually nonexistent unless they are smokers. All that said, this review does provide some evidence that vaping is less harmful -- however I'd take it with a pinch of salt. For example, these two papers on negative effects of vaping on gene expression in the immune system have since been published: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4819171/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4819171/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5436899/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5436899/ (Reported in the popular science press e.g. here: https://www.sciencedaily.com/releases/2016/06/160620141317.htm https://www.sciencedaily.com/releases/2016/06/160620141317.h...)