Read: The actual harms of vaping

Further galvanizing the e-cigarette debate is the frightening rash of vaping-associated pulmonary injuries. The outbreak started in midsummer and has now afflicted more than 1,400 people, causing 33 deaths. Health officials have traced the majority of these tragedies to vaping with contaminated cannabis products. The FDA has specifically warned against using THC products, especially those purchased on the street, but not against commercial e-cigarettes. Nevertheless, the outbreak has been persistently and wrongly attributed to vaping retail nicotine.

When flavored vapes are no longer available, many nicotine users won’t just quit. Instead, some will use cigarettes. Others will turn to the unregulated black market to continue buying fruit-flavored e-cigarettes, for which adult vapers as well as teens have a strong preference. Politicians who ban flavors should brace for a surge in smoking and the use of questionable bootleg vaping products—not just by adult vapers but by teens, especially those who vape daily.

Why don’t politicians see the damage they are about to inflict? In large part, it is because so many wrongly believe that e-cigarettes are as bad, or worse, than cigarettes.

The difference between conventional, tobacco-burning cigarettes and electronic ones can save lives. Standard cigarettes produce 7,000 chemical compounds, including 70 known human carcinogens. In contrast, electronic cigarettes heat a solution of nicotine, propylene glycol, glycerin, and flavorings. Although the aerosol emitted contains toxins and metals, they are far fewer in number than those found in cigarette smoke and they are present at much lower levels.

When I began following electronic cigarettes in 2014, the technology was being hailed as a major public-health advancement for smokers who could not, or would not, quit. Media coverage was tentatively optimistic. Five years later, vaping’s public image in the United States has changed for the worse.

The relative safety of e-cigarettes has been recognized abroad. Public Health England, the British equivalent of the CDC, has estimated that e-cigarettes are at least 95 percent less hazardous than conventional cigarettes. Some British hospitals house vape shops, and the month-long national anti-smoking campaign, Stoptober, encourages people to vape instead.

The long-term health effects of regularly inhaling propylene glycol, glycerin, and flavors are unknown, so researchers must follow vapers for years to come. But that uncertainty should not discourage smokers who have failed to quit smoking through other means (such as gum, the patch, medications, or behavioral therapy) from switching to e-cigarettes.

Read: Juul’s new marketing is straight out of Big Tobacco’s playbook

The U.S. adult smoking rate has fallen to 14 percent, the lowest ever recorded. Vaping has undeniably helped. Vaping achieved twice the one-year quit rates as gum, patches, and lozenges in a rigorous, randomized clinical trial. Vaping is more popular among would-be quitters than nicotine patches and gum combined, according to research from the CDC. And flavors are key to vaping’s appeal for the country’s 11 million to 14 million vapers. A 2018 preference survey of 70,000 adult vapers found that fruit and dessert flavors are the most popular by far, with only a minority using tobacco flavors. It is virtually inevitable that banning flavors to make e-cigarettes less appealing to teenagers will simultaneously jeopardize adults who vape in place of smoking.