Co-op and condo boards in Riverdale are fighting new regulations that would block smoking in residential buildings' common areas like lobbies, hallways and elevators.

Public health advocates point to the dangers of secondhand smoke. But opponents of the ban say it could lead to other restrictive rules -- ranging to cover things like noise, children, appliances or even carpeting.

City Council passed the smoking ban bill unanimously, but Mayor Bill de Blasio has not yet signed it into law.

If he does approve it, it would take effect next year.