"It's not combustible. You're not grappling with the same toxic chemicals," he said, adding he's so confident that vaping is safe, he does it at home, in front of his two young children.
While public health officials agree that e-cigarettes appear to be far less pernicious than tobacco, they say that the lack of scientific data is the very reason bans are needed.
"Research hasn't kept up with the burgeoning of the trend," said Andrew Hyland, a department chairman at the Roswell Park Cancer Institute in Buffalo, N.Y., a major center for e-cigarette research.
Hyland, who testified in Philadelphia for the 2007 bill banning cigarette smoking in public spaces, said e-cigarettes warrant the same restrictions.
The Food and Drug Administration does not regulate e-cigarettes, but it is in the process of attempting to expand its jurisdiction to cover them. In 2009, the agency tested samples from cartridges and found nitrosamines, a known carcinogen, and other poisonous substances including diethylene glycol, found in antifreeze.
"You don't need thousands of studies to show that there are dangerous chemicals emitted," Hyland said. "Those who think electronic cigarettes are safe are fooling themselves."
In April, when Mayor Nutter signed bills banning the sale of e-cigarettes and similar devices to minors and limiting their use, he said that "erring on the side of caution is important for the health, safety, and welfare of all of our citizens."
In 2010, New Jersey became the first state to ban the use of e-cigarettes in most public places. With its new law, Philadelphia joins major cities such as Boston, Chicago, Los Angeles, and New York.
Pennsylvania doesn't regulate e-cigarettes, and the $2-per-pack cigarette tax that Gov. Corbett is expected to sign to provide revenue for city schools will not apply to the devices.
E-cigarette technology has evolved rapidly since the first patents were issued in 1992. The latest generation of mechanisms was developed in China and came to the United States around 2007. As the trend has taken off, marketing has shifted into high gear.
"Now you can enjoy the full effects of smoking and nicotine without the negative aspects of traditional cigarettes," touts an ad for Regal Cigs. "Most people don't realize that cigarettes contain over 4,000 toxic chemicals and carcinogens. . . . Electronic cigarettes . . . deliver nicotine through water, and allow the user to exhale only vapor. ... Celebrities have realized that Regal Cigs are the leading tobacco alternative to stay looking young, feel great, and reduce serious health risks."
Public health officials worry that teenagers will be seduced by the candy and fruit-flavored e-liquids, which may contain unhealthy compounds and lead to vaping nicotine-based liquids.
However, without more data, they say, there is no way to know if e-cigarettes will turn out to be like Shirley Temples containing Red Dye No. 3 maraschino cherries, or alcopops like Mike's Hard Lemonade.
"Research is trying to keep up, but is not able to move at the pace that capitalist business can," Hyland said.
This year, Cynthia Cabrera, executive director of Smoke Free Alternatives Trade Association, which represents the e-cigarette industry, said some regulation is needed to protect minors. She supports manufacturing standards and childproof packaging with warning labels.
At Love Vape, Chy Kan, 18, a Bartram High School senior who works there as a salesman, doesn't object to banning sales to anyone under 18, "because it does go into your lungs." Still, he said, a lot of teens like him start smoking tobacco in middle school and would be better off using e-cigarettes.
"It feels a lot more safe," he said. "I think of it as the vapor used to help babies feel better."
Nearly all the clients in the shop in early July said they used vaping to wean themselves off nicotine.
Tom Nyeng, a 29-year-old computer technician, said he quit smoking two packs a day when he took up vaping nicotine e-liquids. "I started strong and worked my way down," he said. "I don't do nicotine anymore."
Such anecdotal evidence is common, but not yet supported by scientific studies, said Hyland.
One study, published in May in the journal Tobacco Control, found that secondhand exposure to vaping makes cigarette smokers crave a nicotine fix as much as real tobacco smoke does.
Even if vaping proves to help smokers quit, Hyland said, the benefits might be outweighed by the dangers of marketing them to young people.
"Do you like Peaches and Cream?" a saleswoman at Love Vape asked a young Mount Airy man, who said he was 21.
"I"m trying vaping for the first time," he said. "It looks better than tobacco."
"I think it will be better for you," the saleswoman said, showing him a $100 starter kit. "It's a lot smoother. And you won't smell like an ashtray."