DENVER -- They are touted as a safer way to smoke: a tobacco-free, batter-powered cigarette you can smoke anywhere and everywhere to get a nicotine fix.

But are electronic cigarettes an interesting way to kick the habit or an illegal health hazard?

"I've been smoking for 12 years," said Littleton resident Russel Robinson. "I had tried everything."

In spite of the patch, the inhaler and the gum, Robinson could easily go through a pack of cigarettes a day. That is, until he discovered something new.

"I don't even want to smoke now," Robinson said. "And I haven't smoked a cigarette in five months."

Not a traditional cigarette anyway.

Robinson has joined an exploding group of ex-smokers turning to electronic cigarettes.

After Boulder-based Smoker Friendly stores started selling the so called "e-cigs" last month, they have been flying off the shelves.

"All of our stores that have received the product have sold out of it at least two or three times," said Cathi Trail, a store manager who credits cigarette prices hitting new highs and another federal tobacco tax hike happening April 1. "I would say about 80 percent of my customers want to try it."

Smokers could be burned, though.

The American Cancer Society is concerned some of the ingredients in the devices, including nicotine and propylene glycol, aren't safe to inhale.

"It's not worth the risk because, in our opinion, the only cigarette that's safe is the one that you don't smoke," said Dianna Hemphill, with the American Cancer Society.

Because the e-cigs can contain nicotine, the FDA has said they are "new drugs" and need FDA approval "to be legally marketed" in the United States.

The lack of regulation does concern some users, who are quick to point to international tests showing that e-cigs are safer than cigarettes.

For Robinson, what matters are the results.

"Within a couple of weeks, I started feeling better. I could go running and not get a shortness of breath," he said.

Health or not, e-cig users say it's less expensive than real cigarettes, which these days may be the biggest incentive for people tired of seeing their money go up in smoke.

The FDA is investigating why stores are selling e-cigarettes and a spokeswoman said they are seizing shipments in customs because most of the products are made in China.