“Why so many public health groups are trying to block them is beyond me,” said Siegel. “Cigarettes are highly toxic and kill 400,000 people a year, while e-cigarettes are not particularly harmful and they’re helping many people quit.”

During his medical internship at Berkshire Medical Center in Pittsfield, Mass., Siegel saw that most people are admitted to the hospital for preventable reasons: smoking, alcohol, drugs, poor diet, and lack of exercise. “We can counsel every patient who walks in the door about smoking,” he said, “but wouldn’t it be more effective to have mass public health campaigns that reduce smoking? You’ll have a much larger impact on the public’s health.”

That’s what led him to a fellowship in the Centers for Disease Control and Prevention’s Office on Smoking and Health after residency. “That experience convinced me that I wanted to pursue an academic career in public health.” But smoking cessation had been Siegel’s passion since he was an undergraduate at Brown. There he lobbied to make Rhode Island the 13th state to ban smoking in the workplace. During medical school, he lobbied for tobacco control laws in Connecticut.

Siegel believes that e-cigarettes can make the big public health impact he’s been waiting for. Users inhale vaporized liquid nicotine from the battery-operated devices that sometimes resemble cigarettes. Nothing burns. There is no tobacco, no smoke, only vapor. Hon Lik, a Chinese pharmacist and former heavy smoker, invented e-cigarettes as a smoking cessation device in 2003 after his father died of lung cancer. Since the products came to the United States in 2007, the FDA has regulated them as tobacco products. A misnomer, Siegel laments, that undermines the good the products could do.

“More than 90 percent of smokers who try to quit fail. E-cigarettes work for them because they simulate actual smoking behavior—the hand motion, the throat hit, the holding of the cigarette, even some of the social aspects. You can [vape] with others in a group,” Siegel said.

But the devices are not FDA-approved for smoking cessation, so ads can’t say that vaping is safer than smoking or that e-cigarettes help smokers quit.

“You have a product that could help the public, and you’re not allowed to tell them what it does,” Siegel said. “No one is arguing that e-cigarettes shouldn’t be regulated. The question is, How?”

To sell their wares, e-cigarette makers resort to the same advertising themes that tobacco companies use—sex, freedom, and independence. This, said Siegel, tells smokers who might otherwise try e-cigarettes that these devices are just more of the same.

Labeling e-cigarettes as tobacco products, Siegel worries, amounts to a missed opportunity for smokers. “The best thing is to quit smoking completely, but very few people are able to do that.” For the rest, Siegel argues, e-cigarettes are far less harmful than tobacco cigarettes. “You’re no longer inhaling tens of thousands of chemicals from tobacco smoke, including more than 60 known human carcinogens.”

Siegel doesn’t argue that the products are completely harmless. Nicotine alone may pose heart risks. It’s about harm reduction for those who would otherwise smoke for life, he said. A 2015 review published in BMC Medicine cites emerging evidence that smokers who switch to e-cigarettes show improvement in airway function and respiratory symptoms. A recent study in the International Journal of Environmental Research and Public Health showed similar outcomes in smokers with asthma who switched to vaping.

“There is a deeply entrenched ideology in tobacco control that, one, anything that looks like smoking could not possibly be endorsed, and two, any addiction is terrible,” Siegel said.

This makes would-be vapers think, “Why bother?” Siegel adds.

Perhaps the only issue on which Siegel and his colleagues see eye to eye is kids. E-cigarette opponents argue that the products should be banned or tightly regulated so that kids don’t take them up. “I’m sure they will ban the sale of these products to minors, and to me, that’s a no-brainer. It makes sense.”

But that’s where Siegel’s and his peers’ common ground ends. E-cigarette opponents argue that vaping breeds nicotine addiction and is a gateway to smoking. “The majority of youth who use e-cigarettes are already smokers. There are some who are nonsmokers who are just experimenting with these products.”

Siegel’s adversaries want to keep e-cigarettes from kids by hiding them from view completely. Siegel said just quit telling kids e-cigarettes are sexy and tell them what they really are.

“You don’t see kids using nicotine patches and nicotine gum. That’s because they know that these are for smoking cessation. And that’s not a cool thing.”