In nearly 40 percent of U.S. homes with parents who smoke, those parents don't have smoke-free rules in place for their kids, a new study finds.

Having a smoke-free home -- where all smoking is done outside -- shields children from exposure to secondhand smoke and also cuts the risk that they'll begin smoking themselves later on, the researchers said.

One expert agreed.

"Smoke-free rules are such an important aspect of tobacco control, particularly for children since they, unlike adults, have less control over their environment," said Patricia Folan, who directs the Center for Tobacco Control at North Shore-LIJ Health System in Great Neck, N.Y.

In the new study, a team led by Ana Martinez-Donate of the University of Wisconsin-Madison looked at data from a 2010-2011 federal government survey. The investigators found that about 60 percent of households with children, and at least one parent who smoked, had a voluntary smoke-free rule in the home.

Such rules were more likely in two-parent homes versus single-parent households, the researchers found. Rules were more likely if parents had a college education, and if household incomes equaled $50,000 or more. Homes with infants were more likely to have smoke-free rules than homes without babies, the study found.

Most parents agreed that smoking should never be allowed inside cars when children are present, including 72 percent of those who did not have a smoke-free rule in their home, the Wisconsin team found.

On the other hand, smoke-free outdoor children's play areas were supported by only 61 percent of parents who did not have a smoke-free rule in their home.

Folan believes more must be done to get smoking parents to think twice about puffing away when kids are near.

"To increase smoke-free rules -- particularly in homes -- a nationwide anti-tobacco media campaign, highlighting the impact of second- and third-hand smoke on children, is needed," Folan said. "An educational campaign in day care centers and schools may also be helpful."

But one other expert believes the real problem is that any parents still smoke at all.

"Although it may sound encouraging that most adults support smoke-free homes, that does not address the role-modeling of the message conveyed by the parents who continue to smoke -- be it inside the home or out," said Dr. Howard Selinger, chair of family medicine at Quinnipiac University School of Medicine in Hamden, Conn.

"What matters is whether these children grow up to be smoking adults or not," he said.
The findings were published June 18 in the journal Preventing Chronic Disease.