Household smoking and respiratory disease in under-five children

Environmental tobacco smoke is an important respiratory tract irritant in young children. To identify factors associated with respiratory disease and determine the main source of smoking exposure in the household, a cross-sectional study of 2,037 children who were immunized in primary health care clinics was conducted (in a sample of 10 out of 38 clinics with 200 children each). Parents answered a questionnaire about children's birth, passive smoking, former and current respiratory morbidity, socio-demographic characteristics, and living conditions. Analysis was based on hierarchical logistic regression. Prevalence of respiratory symptoms was 59.9% for children who live with smokers. Asthma and bronchitis showed the strongest association with smoking. In multivariate logistic regression, the following variables remained associated with asthma/bronchitis: socioeconomic status (OR = 2.93; 95%CI: 1.57-5.45), maternal schooling (OR = 1.46; 95%CI: 1.08-1.98)] and occupation (OR = 1.68; 95%CI: 1.04-2.74), neighborhood (OR = 1.47; 95%CI: 1.06-2.02), child's age (OR = 3.38; 95%CI: 2.31-4.95) and sex (OR = 1.46; 95%CI: 1.09-1.94), breastfeeding (OR = 1.66; 95%CI: 1.15-2.40), and household smoking (OR = 1.58; 95%CI: 1.18-2.11). Children with lower socioeconomic status and exposed to household smoking showed increased risk of respiratory disease.