Electronic cigarettes, also called vapor cigarettes, are gaining popularity and igniting disputes over whether they're a positive alternative to tobacco. Users inhale nicotine through a liquid that’s heated into vapor, which is a fine mist. The new product, powered by a tiny battery, eliminates deadly tar while offering the sensation of smoking and the stimulation of nicotine -- a natural drug that makes cigarettes addictive. Research suggests that e-cigarettes deliver nicotine faster than gum or lozenges, two smoking habit "cures" that never took off.

Sales of e-cigarettes more than doubled last year from 2012, to $1.7 billion. Even major tobacco firms sell them. Backers see cigarette look-alikes as an advance that could do to cigarettes what computers did to typewriters. Others fear that e-cigarettes may undercut the decline in U.S. smoking. The worry that the socially acceptable gadgets make mock smoking attractive and will introduce teens to the deadly, old-fashioned habit. Critics also worry that adult smokers will stay hooked longer because they can get a nicotine fix at their desks and other spots where smoking is banned or inconvenient, rather than decreasing their dependency as with other methods.

One concern is that students who never smoked are trying the new tools, which are sold online. Liquids that make their vapor come in fruit and dessert flavors like apple pie, banana cream, chocolate, mango, blackberry, watermelon and dozens more. "Middle schoolers are starting off with e-cigarettes and then progressing to conventional cigarettes," warns Dr. Thomas Frieden, director of the federal Centers for Disease Control. Smoking remains the single largest cause of preventable death in America, killing about 480,000 people a year.

Backer says: "The electronic cigarette is the first harm-reduction product to gain serious traction among American smokers. Yet the public health community is not cheering." – Joe Nocera, New York Times columnist

Critic says: "E-cigarettes seem like a good idea, but they aren't." – Stanton A. Glantz, professor of medicine at the University of California-San Francisco

City proposals: New York City and Chicago may add e-cigarettes to their bans on smoking in bars, restaurants and parks.