Likewise, the “just say no” campaigns and “scared straight” programs on drug prevention may have done more harm than good. Most studies of the anti-drug program D.A.R.E. have found no benefit to the intervention, and some have even shown that teens who take part in these programs are more likely to smoke and drink, rather than being deterred. So, the net public health impact was negative, despite the well-meaning intentions.

Niaura: A harm reduction approach, which aims to minimize negative consequences rather than promote abstinence, may be more effective than prohibition at addressing certain public health issues. Take sex education as an example. Comprehensive sex education explains that abstinence is the only guaranteed way to prevent pregnancies and STDs, but it also gives guidance on how to reduce risks for teens who choose to be sexually active. Harm reduction can embrace abstinence and give practical advice to those who won’t abstain.

Unfortunately, abstinence-only sex education is still common, and it has consequences. In a recent study, teens who signed a pledge to not have sex before marriage were more likely to contract an STD and get pregnant out of wedlock, a result of abstinence-focused messaging that downplays the effectiveness of condoms and other contraceptives.

A growing body of research points to using harm reduction for smoking cessation. While quitting smoking—or never starting—is ideal, if you’re going to smoke, you can minimize your exposure to the toxins in cigarettes by switching to safer nicotine products like e-cigarettes.

What are the potential consequences of banning e-cigarettes in a city?

Abrams: Smokers would have to use regular cigarettes or go to great lengths and greater expense to get their vape products—for instance, traveling to a nearby town to buy e-cigarettes, or purchasing them from a black market created by a ban. Basically, it would help keep people smoking deadly cigarettes and the little cigars or cigarillos that appeal to teens. That is the opposite of what we want.

Who benefits from an e-cigarette ban? Who loses?

Niaura: Very few teens will benefit. Most teens who do not already use other tobacco products will not vape either.

Abrams: All tobacco smokers lose, especially populations with the highest smoking rates, including those in the LGBTQ+ community, lower income and uninsured groups, substance users, the mentally ill, and others in society who may have no political voice. They all suffer if we take away less harmful products and make them more expensive and harder to get.

The FDA has taken some steps to begin regulating e-cigarettes, although the San Francisco ban seems to be a response to that process moving too slowly. What role can the federal government play here?