Air pollution mixtures and cognitive outcomes in children: associations with school-age exposure and sex differences

Kou, Xiruo; Canals, Josefa; Arija, Victoria · 2026 · Crossref

DOI: 10.1007/s00431-026-06841-6

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Summary

This study investigates the association between exposure to mixtures of traffic-related air pollutants and cognitive outcomes in preschool-aged children, with a specific focus on potential sex differences. While ambient air pollution is known to impair neurodevelopment, most existing research relies on single-pollutant models that fail to capture the combined effects of co-occurring pollutants. This cross-sectional analysis addresses this gap by evaluating both individual and joint exposures to pollutants including PM2.5, PM10, coarse particulate matter (PMcoarse), nitrogen oxides, and ozone, and their impact on cognitive function. The research utilized data from the ECLIPSES cohort in Tarragona, Spain, comprising 286 children assessed at age four. Air pollution exposure was estimated at school addresses using land use regression models derived from the ESCAPE and ELAPSE projects, temporally adjusted to align with school attendance periods. Cognitive function was measured using the Wechsler Preschool and Primary Scale of Intelligence–IV (WPPSI-IV), which provides indices for verbal comprehension, fluid reasoning, working memory, and processing speed. Statistical analyses included multivariable linear regression for individual pollutants and weighted quantile sum (WQS) regression for mixture effects, adjusting for covariates such as maternal age, socioeconomic status, parental intelligence, and residential greenness. Missing data were handled via multiple imputation. Results indicated that higher exposure to PMcoarse and PM10 was inversely associated with the Working Memory Index (WMI) in the overall population. Sex-stratified analyses revealed stronger negative associations for these pollutants in boys. Specifically, PMcoarse and PM10 showed significant inverse associations with WMI in boys, while PM10 was also associated with lower verbal comprehension and nonverbal indices in boys. In girls, PMcoarse was associated with lower WMI. WQS analysis confirmed a negative association between the overall pollutant mixture and WMI, with PMcoarse identified as the primary contributor. Sex-stratified WQS models suggested that the mixture was associated with lower verbal comprehension in girls and lower working memory in boys, highlighting distinct vulnerability patterns by sex. The findings demonstrate that school-age exposure to air pollution mixtures is associated with reduced cognitive performance in preschoolers, particularly affecting working memory. The study underscores the importance of using multi-pollutant models to accurately assess environmental risks, as single-pollutant approaches may obscure the contributions of specific constituents like PMcoarse. Furthermore, the observed sex-specific differences suggest that boys and girls may exhibit different susceptibility patterns to air pollution-induced neurodevelopmental deficits. These results imply that public health strategies and preventive measures should consider both the complex nature of pollutant mixtures and potential biological differences in sex-specific responses to environmental toxicants.

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• cognitive capacity variation