Yesterday San Francisco became the first major city in the United States to ban the sale of e-cigarettes, a decision that undermines public health in the name of protecting it. Supporters of the new ordinance, which was unanimously approved by the Board of Supervisors, offered two main rationales, both of which sound sensibly cautious but neither of which makes sense after a moment's thought, which apparently was more than San Francisco's supposedly enlightened and progressive leaders could spare.

First, the supervisors worry that e-cigarettes "have not been reviewed by the FDA to determine if they are appropriate for the public health." Neither have conventional cigarettes, which are indisputably much more hazardous and will nevertheless continue to be legally sold by San Francisco merchants. If the supervisors were truly concerned about public health, they would not be favoring a form of nicotine delivery that exposes consumers to the products of tobacco combustion over competing products that do not. They would recognize, as the FDA has, that e-cigarettes offer smokers an alternative that can save their lives by dramatically reducing the toxins and carcinogens they inhale along with nicotine.

Second, the supervisors worry about "the widespread use of e-cigarettes by youth." To prevent underage consumption, they reason, sales to adults must be prohibited. The same logic, of course, applies to combustible cigarettes, alcohol, and any other potentially dangerous product that minors are not legally allowed to buy. Yet with these other products, the supervisors recognize that enforcing the minimum purchase age is a more appropriate response than treating adults like children. The decision to ban e-cigarette sales in the name of limiting youth access is inconsistent not only with the city's treatment of conventional cigarettes and alcoholic beverages but also with the ordinance itself, which allows e-cigarette sales to resume after the products have passed FDA review. The FDA's stamp of approval will not make underage consumption magically disappear.

Nor will San Francisco's ban do anything to mitigate the problem identified at the beginning of the ordinance: the "countless human beings whose lives are forever devastated by the irreparable loss of a loved one caused by tobacco use, and the inevitable rupture of family that follows such a loss." To the contrary, the e-cigarette ban will contribute to that problem by making it harder for smokers to obtain products that deliver nicotine without tobacco or combustion.

"On the face of it, it's ludicrous that we would ban e-cigarettes, but permit the sale of tobacco and cannabis," Steven Schroeder, a professor of health at the University of California, San Francisco, told The New York Times. "It's really smart politics but dubious public health."

University of Michigan tobacco researcher Ken Warner likewise questioned the public health rationale for the e-cigarette ban, noting that increased vaping has been associated with an accelerated decline in smoking. "We have this very big increase in quitting in the U.S.," he told the Times. "We need to keep our eye on the prize, which is the reduction in cigarette smoking. That's what's killing people."

While the ban may be welcomed by middle-class parents worried about adolescent vaping, Schroeder said, it will hurt people with less political influence who could benefit by substituting e-cigarettes for the conventional kind. "Who are the smokers who could benefit?" he said. "They are the downtrodden: the homeless, the HIV positive, substance abusers, prisoners, who have no constituency politically."

Furthermore, relatively affluent smokers can better afford to stock up on e-cigarette pods before the ordinance takes effect in seven months. They will find it easier to evade the ban by ordering e-cigarettes and e-liquid online, a potentially more expensive option that requires a fixed address. (Juul, which is based in San Francisco and accounts for about 70 percent of the market, charges for shipping on orders of less than $50.) Middle-class smokers also can more readily buy e-cigarettes in other cities, since they are more likely to have cars and flexible work schedules.

Although the Times says the e-cigarette ban fits San Francisco's "long history of using ordinances to push progressive causes," there is nothing progressive about it. The ordinance represents the worst sort of "public health" meddling: progressive on its face but regressive in practice, politically appealing but scientifically uninformed, paternalistic yet damaging to the people it supposedly helps, and inimical to the avowed goals of its advocates.