A 29-story office building at 123 Mission St. in San Francisco illustrates the policy puzzles that fester because of these facts: For centuries, tobacco has been a widely used legal consumer good that does serious and often lethal harm when used as it is intended to be used. And its harmfulness has been a well-established and widely publicized scientific proposition for generations.

The building is the headquarters of Juul, a large company that markets vaping products — electronic cigarettes — that has been running full-page ads in major newspapers ostensibly attempting to limit sales of its product: "Youth vaping is a serious problem" that justifies "cracking down on underage sales at retail stores" and removing from stores "flavored products." Juul's flavors include mint, mango, fruit and cucumber. Other companies' flavors have included "Unicorn Puke" and "Zombie Juice." The target audience is not mature.

This city, Juul's host, recently banned such products from being sold in stores or online and delivered to city addresses. Its purpose is to limit cigarette smoking, the nation's foremost cause of preventable death. Well.