Effect of environmental tobacco smoke exposure on respiratory symptoms in children. SCARPOL Team. Swiss Study on Childhood Allergy and Respiratory Symptoms with Respect to Air Pollution, Climate and Pollen.

AIMS: This study determines the prevalence of exposure to environmental tobacco smoke and its relation to respiratory and allergic symptoms among schoolchildren in Switzerland.

METHODS: We studied 4470 children aged 6-14 years as part of a multicentre study (SCARPOL study--Swiss Study on Childhood Allergy and Respiratory Symptoms with Respect to Air Pollution, Climate and Pollen) conducted in Switzerland between 1992 and 1993. Environmental tobacco smoke exposure, maternal smoking during pregnancy and respiratory symptoms were assessed by means of a self-administered parental questionnaire.

RESULTS: Forty-seven percent of all children were exposed to environmental tobacco smoke. Sixteen percent of the mothers smoked during pregnancy. Children exposed to environmental tobacco smoke at home had an increased risk of respiratory infections (odds ratio (OR) 1.19, 95% confidence intervals (CI) 1.03, 1.37). The risk increased if they were exposed to maternal smoking (OR 1.25, CI 1.06, 1.48) and if the mother also smoked during pregnancy (OR 1.42, CI 1.14, 1.76). Wheezing (OR 1.36, CI 1.03, 1.80) and repeated coughing (OR 1.36, CI 1.14, 1.61) were only associated with maternal smoking. Children exposed to more than 20 cigarettes per day were at highest risk for respiratory problems.

CONCLUSION: Almost half of all schoolchildren in Switzerland, especially those from lower socioeconomic classes, are exposed to environmental tobacco smoke. Children with environmental tobacco smoke exposure suffer significantly more often from respiratory symptoms. Maternal smoking during pregnancy additional to current smoking further increases the risk of respiratory morbidity. These findings underline the importance of prevention strategies to reduce the prevalence of smoking and its impact on children's health.