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

Abstract

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 4-5years 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 1.12ms [95% CI; 0.22 a 2.02] per 10μg/m³ increase in prenatal NO₂) and increased omission errors (6% [95% CI; 1.01 to 1.11] per 10μg/m³ 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 10μg/m³ 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 4-5years of age.

Keywords: Air pollution; Attention deficit disorder with hyperactivity; Child development; Cognition; Environmental pollution; Neuropsychological test.