Associations between air pollution and surrounding greenness with internalizing and externalizing behaviors among schoolchildren

Abstract

Air pollutants; Child mental health; Green spaces

Contaminantes del aire; Salud mental infantil; Espacios verdes

Contaminants de l'aire; Salut mental infantil; Espais verds

Background Air pollution and greenness are emerging as modifiable risk and protective factors, respectively, in child psychopathology. However, research shows inconsistencies. Here, we examined associations between air pollution and surrounding greenness with internalizing and externalizing behaviors. In addition, the potential modifying role of the genetic susceptibility for these traits and socioeconomic status (SES) was explored. Methods This population-based study included 4485 schoolchildren aged 5–18 years from Spain. Internalizing and externalizing behaviors were assessed using the Child Behavior Checklist (CBCL). Average air pollution (NO2, PM2.5, PM10, PMcoarse, and PM2.5 absorbance) and surrounding greenness (NDVI within 100-m, 300-m, and 500-m buffers) school exposure were estimated for 12 months before outcome assessment. Genetic liability was assessed by computing polygenic risk scores (PRS) and SES was calculated using the Hollingshead Four-Factor Index. Associations were analyzed using negative binomial mixed-effects models. Results Although no associations survived multiple testing, we found that increases of 5.48 μg/m3 in PM10 and 2.93 μg/m3 in PMcoarse were associated with a 6% (Mean Ratio (MR) = 1.06; 95% CI: 1.01–1.12) and a 4% (MR = 1.04; 95% CI: 1.00–1.09) increase in internalizing behavior scores. A 0.1 increase in NDVI within a 100-m buffer was associated with a 6% decrease in externalizing behavior (MR = 0.94; 95% CI: 0.89–0.99). Neither differences by sex or age, or moderation effects by PRS or SES, were observed. Conclusions We found preliminary evidence of detrimental effects of air pollution on internalizing behavior and protective effects of greenness on externalizing behavior, which were not modified by sex, age, SES, or genetic liability. If confirmed, these results reinforce the need for improving air quality, especially around schools, as part of preventive strategies focused on childhood psychopathology.

This work was supported by the Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR, 2017SGR-1461, 2021SGR-00840), the Instituto de Salud Carlos III (PI19/01224, PI20/00041, PI22/00464 and PI23/00404, PI23/00026, PI24/00195 and FI18/00285 to L.V.R), the Network Center for Biomedical Research (CIBER) to J.C.D.; the European Regional Development Fund (ERDF); the ECNP Network ‘ADHD across the Lifespan’; ‘La Marató de TV3’ (202228-30 and 202228-31), Fundació ‘la Caixa’, Diputació de Barcelona, ‘Pla Estratègic de Recerca i Innovació en Salut’ (PERISSLT006/17/285); ‘Fundació Privada d'Investigació Sant Pau’ (FISP); and Ministry of Health of Generalitat de Catalunya. SA and MSA acknowledge their Miguel Servet contracts (CP22/00026 and CP22/00128, respectively) awarded by the Instituto de Salud Carlos III and cofunded by the European Union Found: Fondo Social Europeo Plus, FSE +. The genotyping service was carried out at the Genotyping Unit-CEGEN in the Spanish National Cancer Research Centre (CNIO), supported by Instituto de Salud Carlos III (ISCIII), Ministerio de Ciencia e Innovación. CEGEN is part of the initiative IMPaCTGENóMICA (IMP/00009) cofunded by ISCIII and the European Regional Development Fund (ERDF).