Arrests have fallen in the past year. More than 26,000 people were arrested in 2014 for criminal possession of marijuana in the fifth degree, which included openly burning a joint and possessing more than 25 grams, according to the New York State Division of Criminal Justice Services. Through September of this year, about 12,500 had been arrested, according to the division’s data. A decision to end the stop-and-frisk policing policy last year may also have contributed to the drop. By comparison, summonses for possession have risen, with the total for this year already surpassing the total for all of last year.

On message boards and blogs, people note that the scent can peak in parts of Brooklyn as the morning commute gears up, with smokers taking drags between sips of coffee. In the spring, Fox News broadcast a report noting the stench on the jogging paths of Carl Schurz Park on the Upper East Side of Manhattan, right next to Gracie Mansion, the mayoral residence. Outside Eataly, the sprawling Italian marketplace in the Flatiron district, the smell from a joint on a recent weekday battled the aroma of espresso beans.

While some New Yorkers’ behavior may have changed, the consequences for possessing a lit joint are still the same — it is a misdemeanor offense punishable by a fine and up to 90 days in jail.

But New Yorkers say it is undeniably in the air.

“Long time ago they used to hide and do it, and now they are doing it out in the open,” Tanya Polite, 49, said as she delivered sandwiches to preschoolers in Williamsburg, Brooklyn. “I smell it a lot. I smell it and go, ‘Pee-ew!’ The smell is so powerful, when you inhale it you get like a contact — a dizzy spell.”

To Ms. Polite and others, open-air marijuana smokers do so to thumb their noses at the police. Others, like Anne Collins, who has lived in Williamsburg for many years, say it is a symptom of an influx of outsiders who bring their values with their suitcases.

“It’s not that it’s New York is a pothead county, or city, it’s you’ve got all these people coming from other places,” Ms. Collins, 53, said. “French, German, Chinese, they are all here. Not to mention all of the Californian yuppies. They carry on their lives as they did where they were.”