Public Release: 

Study discovers a way to keep infants safe from second-hand smoke

Dana-Farber Cancer Institute

BOSTON - Using a form of counseling aimed at motivating rather than preaching, researchers at Dana-Farber Cancer Institute helped smokers reduce by nearly one-third the amount of dangerous second-hand smoke their young children were exposed to, according to a new study.

The results of the Project KISS study (Keeping Infants Safe from Smoke) are encouraging and show that even addicted smokers can change their behavior when they are part of an intervention that provides objective information about the risk that smoking poses for them and their families.

The study's lead author Karen M. Emmons, Ph.D., of Dana-Farber Cancer Institute says the report being published in the July 5 issue of journal Pediatrics is the first to yield objective evidence that an effort to reduce healthy children's second-hand smoke could lead to a significant reduction exposure in children.

"We think a 30-percent reduction in exposure is quite meaningful,'' says Emmons, adding that the scientists are now conducting analysis of the children's health data for the year following the trial to determine whether their health improved. Overall, those involved in the study began smoking outside or using other strategies to lower nicotine levels in the rooms where the children spent most of their time. The improvement in the air quality lasted at least six months, the length of the follow-up period.

In a key part of the experiment, the researchers used monitors to detect nicotine in the air of the families' homes, giving the smokers an objective readout of the extent to which their indoor air was contaminated.

The intervention proved more effective than a set of "self-help'' materials given to a comparison group of smoking parents. In those smokers' homes, nicotine levels actually rose during the study. "There haven't been many previous studies on reducing second-hand smoke, and virtually none of them showed a reduction in healthy kids' exposure using objective measures of exposure,'' says Emmons.

Young children exposed to passive, or second-hand, smoke have a higher risk of ear infections, asthma, bronchitis and pneumonia than children of non-smokers. In the United States, surveys show that almost 40 percent of children under five live with a smoker. Yet there have been few studies of ways to protect children from the harmful effects of tobacco smoke, Emmons remarks.

Project KISS focused on low-income parents of young children, because that socioeconomic group has the highest rate of smoking. The researchers recruited 291 parents or caregivers of children younger than three years through community health centers in Boston and Providence, R.I.

The parents in the study group received a 30-to 45-minute "motivational interviewing'' session at their home with a health educator, and four follow-up counseling calls over the duration of the project. A comparison group was mailed a smoking cessation manual and a passive smoke reduction tip sheet, but received no personal counseling.

"Motivational interviewing'' is a style of counseling that emphasizes personal responsibility for decisions and changes, and helps people identify steps they might want to take. Rather than trying to persuade the smokers to change their behavior, the motivational interview "is a more-respectful strategy that says, 'we can't make this choice for you, but here is some information that might be of use to you','' says Emmons.

The health educators used the readouts of nicotine-sensing air samplers to give the participants an objective measurement of air quality in their home. The message is "we measured the nicotine level in your home and it's about the same as in the bar down the street','' Emmons says. That might help the parent understand why her child has so many respiratory symptoms, she continues. "Then we would ask, "What do you think you might do?''

The same health educator made four following-up counseling calls to check in on the participants' progress and to offer help in meeting the goals the parents had set. Repeat air measurements at the end of six months found that nicotine. Nicotine had actually risen, though not by a statistically significant amount, in the homes of the comparison group. Despite the improvement in air quality in the study group's homes, the researchers

noted that the average nicotine level was still higher than in a typical smoke-free home, leaving the children with some residual risk for passive smoke-related disease. The results suggest that a supportive counseling style, emphasizing a problem-solving approach, may be the best in this situation. Longer-term studies are needed to find out whether the parents can maintain their improved air quality.


Dana-Farber Cancer Institute is a principal teaching affiliate of the Harvard Medical School and is among the leading cancer research and care centers in the United States. It is a founding member of the Dana-Farber/Harvard Cancer Center (DF/HCC), a designated comprehensive cancer center by the National Cancer Institute.

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