A ban on electronic cigarettes has come into effect in New York restaurants, bars, parks, beaches and other public places.
The new law, passed by the city council on December 19 and signed by former mayor Michael Bloomberg, adds to a strict ban on tobacco smoking in public places in the metropolis, where even some residential buildings don't allow tenants to light up.
In a further unprecedented move for a major US city, retailers as of May 18 will no longer be allowed to sell tobacco products or e-cigarettes to anyone under 21.
Restrictions on the use of the battery powered devices in most indoor public places in Chicago also went into force on Tuesday.
In Los Angeles, meanwhile, lawmakers voted in March to ban e-cigarette use in public places where tobacco smoking is prohibited.
Marketed as aids to quit smoking, e-cigarettes allow users to inhale a nicotine-laced vapor. But experts say not enough is known about the effect of chemicals involved, both on smokers or those around them.
