Figure 1

The long-term impact of smoking and e-cigarette use on public health – year 2050. The risk models are based on assumptions of prevalence of smoking and prevalence of use and harm of electronic cigarettes (EC). Harm of smoking is known to be extremely high; this is our reference. Maximal harm = 100. In a harm reduction perspective the harm of EC-use is estimated as extremely low/very low = 1 or 5. In a public health perspective the harm of EC-use is estimated low/moderate = 10, 15 or 25. Harm reduction perspective: Smoking scenario 1: the theory assumes that smokers are reluctant to quit and smoking rates will remain high (15% smokers, harm =100). E-cigarette scenarios: the theory assumes that harm of EC-use is extremely low/very low and use will be restricted to smokers only. EC-scenario 1: 10% of the population use ECs, harm = 1. EC-scenario 2 (worst case): 20% of the population (primarily smokers) use ECs, harm = 5. Public health perspective: Smoking scenario 2: the theory is that smokers wish to quit and tobacco control efforts are effective. Smoking rates will reduce steadily over the next decades (5% smokers, harm =100). Smoking scenario 3 (worst case): EC-use might undermine smoking cessation and renormalize conventional smoking, and the smoking rates might increase. The harm indicated as squared is the extra harm indirectly caused by ECs (30% smokers, harm = 100). E-cigarette scenarios: according to the theory we might underestimate long-term harm of ECs, and use of ECs might spread to a large part of the population EC-scenario 3: 20% of the population use ECs, harm = 10. EC-scenario 4: 30% of the population use ECs, harm = 15. EC-scenario 5 (worst case): 40% of the population use ECs, harm = 25.