In Duluth, people puffing on electronic cigarettes will face the same restrictions as those smoking their traditional, tobacco counterparts. The City Council on Monday approved laws prohibiting e-cigarettes in public places, further flaming an already heated debate about how to regulate the quickly growing industry.

“Generation after generation” allowed harmful cigarettes to go unregulated, said Jennifer Julsrud, a City Council member who introduced the ordinances. “Why not do it the right way this time around with e-cigarettes and put in place reasonable, common-sense restrictions?”

Cities across Minnesota that are considering their own rules about how e-cigarettes are sold and smoked have watched as anti-smoking advocates and e-cigarette supporters bombarded Duluth officials with calls, letters and hours of testimony about the battery-powered devices that trade smoke for a vapor mist often tinged with nicotine. One City Council member got e-mails from as far as England.

Fans of “vaping,” the e-cigarette equivalent to lighting up, say it’s a healthier alternative to smoking that’s helping many people quit. One memo to the City Council called e-cigarettes “one of the most significant public health innovations of the last half-century.” But while health experts acknowledge that the lack of secondhand smoke is a plus, they argue that much more research is needed on whether e-cigarettes offer an effective and safe way to stop smoking.

The rules come less than a week after news that the share of middle- and high-school students who have used e-cigarettes more than doubled in just one year — from 4.7 percent in 2011 to 10 percent in 2012. That new data, released Thursday by the Centers of Disease Control and Prevention, alarmed public health officials who worry that advertisements aimed at young people are undoing decades of work to keep children from smoking.

The Minnesota Department of Health supported Duluth’s ordinances and is discussing whether Minnesota ought to regulate e-cigarettes at a statewide level, said Dr. Edward Ehlinger, health commissioner. State law already prohibits their sale to minors.

“There are so many unanswered questions that I would rather take a precautionary approach,” Ehlinger said. But “we’re not quite there yet” on the specifics of such a strategy, he added.

Some cities have restricted the sale of e-cigarettes, much like conventional ones. Last spring, the St. Paul City Council thought about going further — forbidding e-cigarettes in indoor public spaces — but later dropped the idea. Minneapolis has not floated such a proposal, Council Member Elizabeth Glidden said Tuesday.

“I’m sure with Duluth taking action, cities are going to continue to looking at restrictions on e-cigarettes,” said Glidden, who heads the council’s Regulatory Energy & Environment Committee.

“But [there’s] no whisper of that yet in Minneapolis.”

E-cigarettes are not restricted under the Minnesota Clean Indoor Air Act, but restaurants, businesses and agencies have adopted their own rules. Metro Transit recently banned e-cigarettes from buses, light-rail cars and its property, a spokesman said. Hennepin County restricts their use on county property.

The Minneapolis-St. Paul International Airport is discussing whether to ban them in areas not leased by airlines or other businesses, which set their own rules.

Target Field tweaked its “no smoking” policy this year to include e-cigarettes. Twins President Dave St. Peter said that “our staff found they created confusion and customer service challenges in the sense that it was very difficult to distinguish … between traditional cigarettes and e-cigarettes.”

An e-juice bar

A dozen e-cigarette specialty shops now dot the metro area, and many tobacco shops now offer e-cigarettes, too. When the Uptown Vapor Shoppe in Minneapolis opened in April, three to 10 customers came by each day. Now, the Minneapolis store averages 50-plus buyers on weekdays and “even more on weekends,” said owner Sina War.

The bright, art-covered space features a “juice bar” where customers sample “e-juice,” the liquid solution that’s heated to create a vapor mist, in flavors ranging from menthol to root beer.

Megan Spence and her mother, Loni, who stopped by Tuesday afternoon, are trying to kick their cigarette habit. Most customers — from 20-somethings to grandmas — are looking to quit, said War, whose business idea began with her own switch to electronic.

“Someone will come in and say, ‘I haven’t had a real cigarette in 10 days,’ and we’ll give him a big high-five,” she said. “They tell us stories about how it’s changed their lives.”

The Consumer Advocates for Smoke-Free Alternatives Association points to studies that show e-cigarettes can help people quit. Another, published in the journal Tobacco Control, concluded that “e-cigarettes as a harm reduction strategy among smokers unwilling to quit, warrants further study.”

Gregory Conley, legislative director for the group, flew in from New Jersey to testify against the new ordinances, saying that they “discourage smokers from switching to lower-risk alternatives.”

Studies have shown “conflicting” results, said Ehlinger. One recent study, in which e-cigarettes were shown to help people quit, was highly supervised. He worries that somebody just going out and buying an e-cigarette, without knowing how to control the levels of nicotine, is “really problematic.”

But even if they’re helping smokers quit, there is growing worry that they might be encouraging nonsmokers to start. Ehlinger would like to see studies on whether e-cigarettes act as a gateway to other tobacco products. “We have millions of students nationwide using something that delivers an addictive product,” he said. “I don’t think that’s a good thing.”

If the medical community later comes to the consensus that e-cigarettes don’t cause harm and help people quit, Duluth can reverse its restrictions, said Julsrud, the council member.

“And if the doctors find it’s not safe,” she added, “then we did the right thing by being cautious.”

Staff writer Michael Rand contributed to this report.