NEW YORK - Smoking is prohibited in 43 square miles of parks, public plazas, beaches, and boardwalks in New York City under a new law that went into effect last month.

The law, with a $50 fine attached, aims to protect New Yorkers from secondhand smoke in often elbow-to-elbow environments. But some health experts question whether the smoke poses a serious danger in open spaces, and critics say the city is trampling on civil liberties.

The New York City Council approved the ban in February. The first day it kicked in felt more like a public-awareness campaign than a strictly enforced, punitive law.

A government ban on smoking is nothing new in New York. The city outlawed smoking in restaurants, bars, and other public indoor spaces in 2002.