RESULTS
This study comprised 5,965 children aged 12 years in TCHS; data of 3233 children from cohort 1 were collected in 2007, and data of 2732 children from cohort 2 were collected in 2012 (Table 1). The BMI and prevalence of active asthma were similar among the two cohorts. In total, 43.2% of the children reported exposure to household cigarette smoking, and nearly half of the children were breastfed.