Mike Hayes was a pack-and-a-half-a-day smoker for 28 years until he found something that made him quit successfully in only two months. Nicotine inhalers, gum, patches and quitting cold turkey didn't work.

What did work was e-cigarettes, something still new enough that no federal regulations are in place because agencies say not enough is known about them.

"I feel like it's saving my life, for sure," said Hayes, a 44-year-old Lowell native now living in Wisconsin.

Smokers like Hayes swear by e-cigarettes, or electronic cigarettes, which are battery-operated and deliver nicotine without tobacco, the odor and the harmful smoke. The nicotine is in liquid form and becomes heated into vapor.

"They are very different than your usual cigarettes," said Dr. Nicholas Hill, the chief pulmonary physician at Tufts Medical Center. "What you get into your lungs is very different."

Though they carry nicotine and tobacco just like cigarettes do, there is no age limit to keep kids from buying them. Many are also marketed toward youths, with colorful packaging and flavors like cherry or chocolate.

They're often also sold as more healthy alternatives to traditional cigarettes, despite reservations from doctors and the Food and Drug Administration and warnings that more study is needed first.

Massachusetts Attorney General Martha Coakley co-sponsored a letter to the FDA last week that was signed by 40 states in all, including all six New England states. The attorneys general urged the FDA to "take all available measures" to issue regulations on advertising, ingredients and sale to minors by an Oct. 31 deadline the FDA set for itself.

There are currently no federal regulations.

"People assume that if they're on the market, they must be safe," Coakley said in an interview.

No Massachusetts regulations are yet in effect either, but state Rep. Jeffrey Sanchez, a Boston Democrat, filed a bill last month that would ban the sale of e-cigarettes to minors and add them to smoking bans in workplaces.

"As the tobacco industry continues to innovate, we must make sure our laws and regulations keep pace," said Sanchez, a co-chair of the Joint Committee on Public Health.

States often lead the way on such regulations, Coakley said. But e-cigarettes have become so common so quickly, it has been hard to keep pace.

"It really is being launched in a really substantial way we haven't seen in other products," she said.

In one year alone, the number of high-school and middle-school students who reported using an e-cigarette doubled, according to a Centers for Disease Control and Prevention study released this month. Among high-schoolers, 10 percent said they tried e-cigarettes.

CDC Director Tom Frieden called the findings "deeply troubling."

"Nicotine is a highly addictive drug," Frieden said. "Many teens who start with e-cigarettes may be condemned to struggling with a lifelong addiction to nicotine and conventional cigarettes."

One in five of middle-schoolers who had smoked e-cigarettes said they never tried traditional cigarettes, which the CDC said raises concerns that e-cigarettes could be an "entry point" for young people to use conventional tobacco products.

Sales of e-cigarettes remain small compared to traditional tobacco products, but this year are projected to hit $1.7 billion, tobacco industry analyst Bonnie Herzog of Wells Fargo Securities has estimated. Much of that will take place online. Sales of e-cigarettes could pass those of traditional cigarettes within a decade, she said.

The FDA intends to expand its jurisdiction over e-cigarettes but hasn't yet done so. The agency said it does not have good information about e-cigarettes because they are largely unregulated, such as the amounts and types of components in the products.

The American Lung Association has also warned against e-cigarettes, saying the unknown about the relatively new product makes it possible that some aspects are more harmful than traditional cigarettes.

Marketing and imaging are as important with e-cigarettes as any other business.

One major e-cigarette maker, White Cloud Electronic Cigarettes, sells cigarette covers and cases for batteries and other accessories in different color combinations said to be for each NFL football team, although the packs carry no team logos. White Cloud comes in apple, coconut, peach and other flavors.

An industry group, the Tobacco Vapor Electronic Cigarette Association, calls the products a "fabulous new technology" and has created a website to respond to what it calls vast amounts of misinformation about e-cigarettes and their health effects.

The medical industry has largely expressed concern while acknowledging e-cigarettes can be a useful way to quit smoking.

Harvey Simon, a Havard Medical School professor and the editor of the magazine Harvard Health, wrote last week that preliminary studies of e-cigarettes "raise concerns."

The products may help smokers quit, he said, but "whether they are a safe way to quit is another question."

Some reasons for concerns, Simon said, include a wide variation in the amount of nicotine delivered in each puff. They may also deliver other harmful chemicals, just as traditional cigarettes do.

"To be sure, the dose of these compounds is generally smaller than found in 'real' cigarette smoke," Simon said. "But it isn't zero."

By simulating the smoking experience, e-cigarettes could also actually reactivate the habit for some, he added. They could also act as a gateway for young people toward becoming hooked on tobacco.

Dr. Hill, the Tufts pulmonologist, said he tells patients that e-cigarettes aren't FDA-approved and their long-term safety is not established. But they can be effective in helping people quit tobacco, he said.

Users say e-cigarettes have done the trick where other methods for quitting failed.

Carmen Ciampa, a 36-year-old construction worker from Tewksbury, smoked two packs a day for 20 years. He tried to quit a few times but finally went for e-cigarettes after his daughter collected cigarette butts outside their home and told him, "Dad, this is disgusting."

A e-cigarette user since last November, he quickly quit tobacco cigarettes.

"I can actually breathe without wheezing or coughing," Ciampa said. He also touts the savings: He used to spend about $20 a day, and now spends only about $4, even though he smokes just as often. Ciampa will occasionally use it in a restaurant, too. Because there is no second-hand smoke, there's no harm to anyone else.

"You get looks," he said, "like, 'Is he really smoking in the restaurant?'"

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