The use of electronic cigarettes (vaping) carries many health risks, especially for children, young adults, and pregnant women. The risk depends on the composition of electronic cigarette aerosol and varies according to the contents of the liquid, the physical and electrical design of the device, and user behavior. As of 2019, the long-term risks of vaping are uncertain because it is a relatively new technology, although the long-term risks of some individual substances in vaping aerosols have been studied. In United Kingdom vaping is considered to be around 95% less harmful than tobacco in a landmark review by Public Health of England. E-cigarette vapor has a different composition than cigarette smoke, and can have lower levels of some toxic chemicals. E-cigarettes reduce lung function, reduce cardiac muscle function, and increase inflammation. Traditional cigarettes have a higher damage record than vaping but inhaling nicotine has its own consequences. The deadly 2019–20 vaping lung illness outbreak in North America was likely primarily caused by vitamin E acetate in THC-containing vaping liquid. Other unidentified chemicals may also cause vaping-associated pulmonary injury. The relationship between nicotine vaping and tobacco smoking is an area of active study and debate; including the relative health risk, whether electronic cigarettes should be promoted as a less harmful alternative to smoking or as a means to quit nicotine entirely, and whether or not the availability of electronic cigarettes recruits more people into nicotine dependence. Nicotine vaping produces more carcinogens and toxic substances than a medically-approved nicotine inhaler. Health concerns extend to nearby people inhaling the vapor exhaled by others, in the same way as second-hand smoke. E-cigarettes create vapor that consists of fine and ultrafine particulate matter, propylene glycol, glycerin, nicotine, flavors, small amounts of toxicants, carcinogens, heavy metals, and metal nanoparticles. The harmful effects of nicotine itself can include cardiovascular disease, possible birth defects, and poisoning. E-liquid can be contaminated by various substances introduced during manufacturing, or by metal particles from the container. Carbonyl compounds such as carcinogenic formaldehyde can inadvertently be produced if nichrome wire heating element becomes too hot. This is more of a concern with higher voltage (5.0 V) vaping devices, which can generate equal or higher levels of formaldehyde compared to smoking and during "dry-puffing". Aside from toxicity exposure in normal use, there are also risks from misuse or accidents. Such accidents can be through nicotine poisoning (especially among small children), contact with liquid nicotine, fires caused by vaporizer malfunction, and battery explosions resulting from extended charging, unsuitable chargers, design flaws, or user modifications.
Safety of electronic cigarettes
Positions of medical organizations on electronic cigarettes
Road traffic safety
Construction of electronic cigarettes
Electronic cigarette and e-cigarette liquid marketing
Bicycle safety
Personal health application
Modesty in medical settings