Early life exposure to fine particulate matter and fine motor function, attentional function, and working memory among Spanish school-aged children

Background: Evidence of the association between fine particulate matter (PM2.5) exposure and child neuropsychological function is equivocal. We examined early life PM2.5 exposure in relation to fine motor function, attention, and working memory in early childhood. Methods: We used data from the Spanish INfancia y Medio Ambiente Project, 2003-2008. Exposure to PM2.5 (μg/m3) was assessed using spatiotemporal land-use random forest models and assigned based on residential address histories. Around age six, children completed the finger tapping test, attentional network test (ANT), and n-back task to evaluate fine motor speed, attention, and working memory, respectively. A total of 1,310 children had data from at least one neuropsychological assessment. General linear models were applied to assess associations between average prenatal and postnatal PM2.5 with each outcome. Distributed lag nonlinear models were used to explore refined periods of susceptibility to PM2.5. We reported β estimates and 99% credible intervals (CrI) representing the change in each outcome per 5-μg/m3 increase in PM2.5. Results: Prenatal PM2.5 exposure was associated with decreased mean hit reaction time (HRT) (β = -21.82; 99% CrI = -64.1, 20.4) and HRT-standard error (β = -9.7; 99% CrI = -30.3, 10.9) on the ANT but estimates were imprecise. Postnatal PM2.5 was associated with reduced mean HRT on the n-back task (β = -39.4; 99% CrI = -115.1, 26.3). We observed sensitive periods of exposure in the postnatal period associated with both better and worse performance on the finger-tapping test and ANT. Conclusions: We found limited evidence to support an association between PM2.5 exposure and fine motor function, attentional function, or working memory in school-aged children.