No one under 21 would be able to buy cigarettes in New York City, under a proposal unveiled Monday to make it the most populous place in America to set the minimum age that high.

Extending a decade of moves to crack down on smoking in the nation’s largest city, the measure aims to stop young people from developing a habit that remains the leading preventable cause of death, City Council Speaker Christine Quinn said as she announced the plan. Eighty percent of the city’s smokers started lighting up before they were 21, officials say.

But the proposal may face questions about its effectiveness and fairness. A retailers’ representative suggested the measure would simply drive younger smokers to neighboring communities or corner-store cigarette sellers instead of city stores, while a smokers’ rights advocate called it “government paternalism at its worst.”

Under federal law, no one under 18 can buy tobacco anywhere in the country. Four states and some localities have raised the age to 19, and at least two communities have agreed to raise it to 21.

A similar proposal has been floated in the Texas Legislature, but it’s on hold after a budget board estimated it would cost the state more than $42 million in cigarette tax revenue over two years.

Several New York City smoking regulations have survived court challenges. But a federal appeals court said last year that the city couldn’t force tobacco retailers to display gruesome images of diseased lungs and decaying teeth.