From Reason Foundation:

The R Street Institute released an excellent evidence update on tobacco harm reduction encompassing e-cigarettes, heated tobacco products, and the smokeless tobacco snus. Regarding the state of the evidence surrounding these products, authors Carrie Wade and Chelsea Boyd write, “It has been conclusively shown that the profile of dangerous constituents, including particulate matter, lack of carbon monoxide and HPHCs is much more favorable in the ANDS discussed than that of cigarettes.”