The vaping-related illnesses that have garnered headlines and prompted the regulatory actions appear not to implicate standard vaping but rather the use of black-market liquids containing THC, the active ingredient in cannabis.

The problem with the flavor bans — and especially a San Francisco-style outright ban — is its effect on adult e-cigarette users.

About 11 million adults vape, and some percentage of them are former smokers or would be smoking in the absence of e-cigarettes. A robust study in the United Kingdom found that vaping is twice as effective as other common nicotine replacements in getting smokers to quit. The flavors, according to surveys of users, are a big draw for smokers quitting traditional cigarettes.

It’s manifestly absurd to ban vaping products and leave cigarettes, including flavored cigarettes, on the market.