The city has launched a new smoking law for apartment buildings.

According to the city, all residential buildings with more than three units must post an official smoking policy for their building.

The law took effect on August 28.

City officials say landlords must post or create a policy on smoking and disclose it to tenants and prospective tenants.

Building owners who fail to create and disclose a policy on smoking will be subject to $100 fines, officials say.

According to the health department, more than half of New Yorkers living in apartments report smelling cigarette smoke from other units inside their buildings.