Prenatal and postnatal exposure to NO2 and child attentional function at 4-5 years of age

Background: Prenatal and postnatal exposure to air pollution has been linked to cognitive impairment in children, but very few studies have assessed its association with attentional function. Objectives: To evaluate the association between prenatal and postnatal exposure to nitrogen dioxide (NO2) and attentional function in children at 4-5 years of age. Methods: We used data from four regions of the Spanish INMA-Environment and Childhood-Project, a population-based birth cohort. Using land-use regression models (LUR), we estimated prenatal and postnatal NO2 levels in all of these regions at the participants' residential addresses. We assessed attentional function using the Kiddie-Conners Continuous Performance Test (K-CPT). We combined the region-specific adjusted effect estimates using random-effects meta-analysis. Results: We included 1298 children with complete data. Prenatal exposure to NO2 was associated with an impaired standard error of the hit reaction time (HRT(SE)) (increase of 1.12 ms [95% CI; 0.22 a 2.02] per 10 mu g/m(3) increase in prenatal NO2) and increased omission errors (6% [95% CI; 1.01 to 1.11] per 10 mu g/m(3) increase in prenatal NO2). Postnatal exposure to NO2 resulted in a similar but borderline significant increase of omission errors (5% [95% CI; = 0.99 to 1.11] per 10 mu g/m(3) increase in postnatal NO2). These associations did not vary markedly between regions, and were mainly observed in girls. Commission errors and lower detectability were associated with prenatal and postnatal exposure to NO2 only in some regions. Conclusions: This study indicates that higher exposure to ambient NO2, mainly during pregnancy and to a lesser extent postnatally, is associated with impaired attentional function in children at 4-5 years of age.