Many parents and pediatricians worry about the appeal of electronic cigarettes to teenagers. And they are not alone. Back in March 2017, for instance, Terry Gordon was contacted by a high school junior about ideas for a science fair project. At one point, the boy mentioned his concern about vaping in the school's restrooms. "A light bulb went off pretty quickly," recalls Gordon, a professor of environmental medicine at New York University (NYU) Grossman School of Medicine. "We decided to take some air measurements to see if vaping was harmful for kids who do not do it themselves." With support from administrators and teachers, the Board of Education, and the Parent Teacher Association, Gordon's team eventually installed air monitors in the restrooms at one high school and one middle school. The vaping-associated nicotine levels the researchers measured in these restrooms were similar to those in New York City public housing units where residents smoked heavily, says Gordon. 1 The jury is still out on whether e-cigarettes are as effective as, or superior to, nicotine replacement therapy to help quit smoking. 2 To date, no e-cigarette has been approved by the U.S. Food and Drug Administration (FDA) as a smoking cessation aid. 3 Although e-cigarettes may not expose users to all of the toxicants produced by tobacco combustion, the health risks associated with exposure to e-cigarette aerosols are not well characterized. 4 This means harm reduction in smokers who switch to e-cigarettes should be weighed against the potential risk to nonsmokers who find vaping much more appealing-and perceive it as safer-than cigarette smoking. The 2019 outbreak of so-called "e-cigarette, or vaping, product use associated lung injury" (EVALI) in the United States also affected many young individuals; more than half were under age 25. 5 Although likely caused by vitamin E acetate added mainly to THC-containing vapes, 5 the event intensified public concern about a simultaneous youth vaping epidemic, supported by growing scientific evidence that e-cigarettes are far from safe. 6 Combustible Cigarettes vs. E-Cigarettes E-cigarettes contain a battery-powered heating element, usually a metal coil, that heats an "e-liquid" mixture of solvents, nicotine, and flavoring chemicals. Users inhale the resulting aerosols into their lungs. Manufacturers are not required to publicly disclose the ingredients in e-liquids (although they must report them to the FDA), and substantial discrepancies exist between the labeled and actual nicotine content of many brands. 7,8,9,10 E-cigarettes appeared on the U.S. market in 2006. 11 Their designs have changed substantially over time. The first-generation The percentage of high schoolers reporting recent e-cigarette use increased from 1.5% in 2011 to 27.5% in 2019. 26 The rapid increase in youth vaping is one reason the FDA is cracking down on manufacturers targeting young consumers with kid-friendly marketing. Image: CC BY 4.0 (cropped original).