This Nov. 26, 2013 photo shows Jesse Forsblade, left, and Mark Bartholomew smoking and drinking coffee at the Smokeless Smoking electronic cigarette store in Woodbury, Minn. Stores that sell increasingly popular e-cigarettes are popping up around the Twin Cities, highlighting both a lack of regulation and new state cigarette taxes that went into effect in July, pushing the cost of a pack to about $7.50. Chris Polydoroff / St. Paul Pioneer Press via AP 2013

Minneapolis City Council members Friday voted to ban the use of electronic cigarettes in the city's public indoor spaces, including bars, stores and commercial workplaces.

E-cigarettes have become popular alternatives to conventional cigarettes in recent years. The devices vaporize nicotine, which users inhale, rather than burning tobacco. Supporters say it's harmless and a far cry from conventional smoking.

Critics, however, say there are no long-term studies on e-cigs and the long-term health effects are unknown. They also cite data showing 28 percent of high school students and 8 percent of middle school students in Minnesota have tried them.

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The new Minneapolis ordinance prohibits electronic cigarette use in all indoor public places in the city. Stores, restaurants and other places of employment can be fined for allowing indoor use, although city officials noted the new rules don't restrict e-cigarette sampling in "exclusive" tobacco or e-cig shops that restrict people under the age of 18 from entering.

Officials say the city's health department will provide businesses with free window decals indicating that smoking, including e-cigarettes, is prohibited indoors.

Minneapolis joins Duluth, Bloomington and Edina in Minnesota in banning the devices in indoor public places. Boston, Chicago and Los Angeles have imposed similar restrictions.