How should parents protect their children from environmental tobacco-smoke exposure in the home?

Background. Children's exposure to tobacco smoke is known to have adverse health effects, and most parents try to protect their children. Objective. To examine the effectiveness of parents' precautions for limiting their children's tobacco-smoke exposure and to identify variables associated to parents' smoking behavior. Design and participants. Children, 2.5 to 3 years old, participating in All Babies in Southeast Sweden, a prospective study on environmental factors affecting development of immune-mediated diseases. Smoking parents of 366 children answered a questionnaire on their smoking behavior. Cotinine analyses were made on urine specimen from these children and 433 age-matched controls from nonsmoking homes. Results. Smoking behavior had a significant impact on cotinine levels. Exclusively outdoor smoking with the door closed gave lower urine cotinine levels of children than when mixing smoking near the kitchen fan and near an open door or indoors but higher levels than controls. Variables of importance for smoking behavior were not living in a nuclear family (odds ratio: 2.1; 95% confidence interval: 1.1 - 4.1) and high cigarette consumption (odds ratio: 1.6; 95% confidence interval: 1.2- 2.1). An exposure score with controls as the reference group (1.0) gave an exposure score for outdoor smoking with the door closed of 2.0, for standing near an open door + outdoors of 2.4, for standing near the kitchen fan + outdoors of 3.2, for mixing near an open door, kitchen fan, and outdoors of 10.3, and for indoor smoking of 15.2. Conclusion. Smoking outdoors with the door closed was not a total but the most effective way to protect children from environmental tobacco-smoke exposure. Other modes of action had a minor effect.