At least 27 lawsuits have been filed since 1991 over smoking in multiunit housing, and judges have often sided with the nonsmoker, Mr. Sweda said.

But many in the real estate industry believe that banning smoking in such buildings would be discriminatory and therefore illegal. When asked by residents to enact a smoke-free policy, property managers often say they cannot because of federal fair housing laws.

In fact, the federal Fair Housing Act protects nonsmokers in cases where people have breathing disabilities aggravated by smoke.

In the summer of 2006, First Centrum, based in Virginia, adopted a smoke-free policy for more than 5,000 units at its 46 apartment communities for older residents in Illinois, Maryland, Michigan, North Carolina, Tennessee and Virginia, said Robert Couch, president of the company’s management division.

Over the last seven years, Guardian Management, which is based in Oregon, has banned smoking in units at five properties, and in August extended that policy to 8,000 rental units at 100 properties in Idaho, Montana, Oregon, Texas and Washington, said Tom Brenneke, the company president.

“It was an easy decision,” Mr. Brenneke said. He said Guardian was motivated primarily by health and financial considerations, and he pointed out that a smoker’s apartment cost $1,500 to clean when a tenant vacated, compared with $400 for a nonsmoker’s.

Cities in California have taken the lead in adopting smoke-free housing ordinances.

On May 8, Temecula passed an ordinance that applies to apartment buildings with 10 or more units. The law requires landlords to designate at least 25 percent of their units, including balconies and patios, as nonsmoking. The ordinance is being phased in over five years.