Nicotine is highly involved in the development of cardiovascular disease, especially atherosclerosis. Although tar and other harmful ingredients have been removed in the e-liquid, more work should be done to evaluate its safety, due to the existence of nicotine and other potential hazards such as aerosol particles and different flavor additives in the e-liquid. These may increase the risk of cardiovascular disease. Moreover, the number and size distribution of particles from E-cigarettes are similar to those from traditional cigarettes, and some E-cigarettes produce more particles than traditional cigarettes. Particles may cause lung and systemic inflammation, and increase the risk of cardiovascular disease, respiratory disease and death .