Starting in late May, it will be illegal in St. Paul to sell electronic cigarettes to those under 18, or for minors to possess them — the same as with tobacco cigarettes.

But e-cigarette use will remain permissible indoors as well as out, unlike smoking.

The City Council last week unanimously approved an ordinance regulating the sale of e-cigarettes, battery-powered devices that look like cigarettes but deliver nicotine through vapor rather than smoke. Some are said not to contain nicotine.

An earlier proposal would have put e-cigarettes under the city's indoor smoking restrictions. That was stripped from the ordinance last month, bringing city code into line with state law.

E-cigarette use is rising, driven in part by claims that it's a safe alternative to tobacco and may actually help smokers kick the habit. However, antismoking groups warn that the health effects are still largely unknown and that inhaling the tobacco-free vapor may expose the user to harmful chemicals.