Exposure to ambient air pollution and executive function among Chinese primary schoolchildren

Evidence on the associations between particulate matter (PM) and nitrogen dioxide (NO₂) exposure with executive function in children is scarce in developing countries. Moreover, few studies investigated ozone (O₃) and sulfur dioxide (SO₂). This study aimed to investigate the associations between long-term exposure to air pollution and executive function in Chinese children.

In 2017, we randomly recruited 5028 children aged 6-12 years from 5 schools in Guangzhou city, southern China. Each of 5028 children's executive function were assessed using parent filled questionnaire. We further randomly selected 522 children to take computerized tests to assess working memory, inhibitory control, and cognitive flexibility. The 1-year average residence-based exposure to PM with diameters ≤2.5 (PM_2.5) or 10 μm (PM₁₀), NO₂, O₃, and SO₂ exposures were estimated by using an inverse-distance weighting approach. Associations were evaluated by mixed linear regression models.

The 1-year average concentrations of PM_2.5, PM₁₀, NO₂, SO₂, and O₃ was 39.06 ± 1.12 μg/m³, 60.95 ± 3.49 μg/m³, 53.64 ± 4.44 μg/m³, 12.33 ± 0.79 μg/m³, and 90.07 ± 7.96 μg/m³, respectively. Each interquartile range increment in PM_2.5 was associated with 48.04 ms [95% confidence interval (CI): 2.18 to 93.89] increase in inhibitory control and 0.72 (95% CI: -1.14 to -0.29) points decrease in forward recall. PM₁₀ exposure was associated with 0.55 (95% CI: -1.04 to -0.06) and 0.67 points (95% CI: -1.09 to -0.25) reduction in forward and backward recall, respectively. SO₂ exposure was associated with 0.69 (95%CI: 0.37 to 1.02) and 0.73 (95%CI: 0.40 to 1.05) high scores of behavioral regulation index and metacognition index, respectively. Significant association was found between O₃ exposure and metacognition index (estimate, 95%CI: 0.87, 0.45 to 1.29). No associations for cognitive flexibility were observed. Stratified analyses did not yield any significant modification effects of sex, physical activity, screen time, and parental smoking.

Long-term exposures to PM_2.5, PM₁₀, SO₂, and O₃ were associated with poorer performance in working memory, inhibitory control, behavioral regulation, and metacognition in children.