Within- and between-study site variations in ambient air pollution exposure at ages 9–10 years in the Adolescent Brain Cognitive Development (ABCD) Study

Background: Minority and socioeconomically disadvantaged children face disproportionate air pollution burdens, yet the geographic heterogeneity and intersectional structure of these disparities remain poorly characterized in pediatric populations. Methods: Using baseline data (2016–2018) from the Adolescent Brain Cognitive Development Study, the largest longitudinal study of child brain development in the United States, we estimated residential fine particulate matter (PM 2.5 ) and nitrogen dioxide (NO 2 ) among 9- to 10-year-olds across 21 sites spanning 19 metropolitan areas. We employed an intersectional analytic approach to examine race/ethnicity and socioeconomic effects jointly, and a two-stage meta-analytic design to explicitly model between-site heterogeneity. Results: Hispanic/Latinx and Black children experienced higher average PM 2.5 and NO 2 than white peers overall, but intersectional analyses revealed that Hispanic/Latinx preadolescents from the lowest income households bore the greatest PM 2.5 burden, and higher educated Black families showed increased NO 2 exposure relative to those with high school diplomas. Site-specific analyses revealed substantial geographic heterogeneity in disparity magnitude, challenging the assumption of homogeneous national patterns. Conclusion: These findings underscore the need for locally targeted interventions. Nearly all participants exceeded World Health Organization air quality guidelines despite meeting Environmental Protection Agency thresholds, highlighting a regulatory gap with particular relevance to children’s developing neurological systems.