[Cigarette smoking of mothers in pregnancy and environmental tobacco smoke as factors of increasing susceptibility of older children to acute respiratory infections].

The purpose of the study was to compare the susceptibility to respiratory morbidity in a cohort of 1129 9-years old children being exposed to congenital and postnatal environmental tobacco exposure with that of not exposed cohort. Results of the study provides strong evidence that older children who were exposed to ETS in their home environment were considerable more susceptible to acute respiratory tract illnesses than unexposed ones. As there was a dose-response relationship between degree of exposure (for lower ETS exposure OR = 1.32; for higher ETS exposure OR = 1.74) and excess rates of respiratory episodes this supports the existence of a causal explanation for the association observed. The significant trend of increased susceptibility in children to respiratory infections with the level of ETS exposure after exclusions of allergy and smoking in pregnancy suggests the existence of direct effect of ETS exposure on the child's respiratory health that is independent of atopy and in utero exposure to tobacco smoke products.