The output of E-cigarettes is huge. The policies and intensity of control are quite different due to the variation in their classification among different countries. At present, there are four main types of policy for the control of E-cigarettes. The first one is prohibition, which means prohibition of the import, sale, usage, advertisement, and public consumption, as well as the sale of E-cigarettes to minors. The second type of policy is to control E-cigarettes as drugs or medical products. The third one is to control E-cigarettes as tobacco products. The final category of policy is to regulate E-cigarettes as electronic products and ordinary consumer goods . The distribution of different E-cigarette control policies in the world are shown in Figure 2 .