Vegetation and vehicle emissions around primary schools across urban Australia: associations with academic performance.

BACKGROUND: Evolving evidence suggests that vegetation surrounding schools is beneficial to children's academic performance, however vehicle emissions are adversely related. Little is known about concurrent impacts of vegetation and vehicle emissions on academic performance. This study examined associations of vegetation and vehicle emissions near urban Australian primary schools with children's academic performance. METHODS: Vegetation within schoolyards and Euclidean buffers (100, 300 and 1000 m) was assessed using the Normalized Difference Vegetation Index (NDVI). Weighted road density (WRD) was computed for each buffer as a vehicle emissions proxy. Cross-sectional associations and mediating pathways between vegetation and vehicle emissions and standardized average academic scores in Literacy (Reading, Writing, Language Conventions) and Mathematics for Grades 3 and 5 attending 3745 primary schools in urban areas (population ≥10,000) of Australia in 2018 were assessed using generalised linear models adjusted for school socio-educational status. RESULTS: Significant positive associations were found between vegetation and Reading in Grades 3 and 5, Mathematics in Grade 3 (all buffers), Writing in Grade 3 (100 and 300 m), and Language Conventions in Grades 3 and 5 (most buffers). Increased vehicle emissions were negatively associated with Reading and Mathematics in Grades 3 and 5 (most buffers), and Language Conventions in Grade 3 (300 and 1000 m) and Grade 5 (100-1000 m). Within 300 m, vehicle emissions partially mediated associations between vegetation with Mathematics in Grade 3 (proportion mediated, 21%), Reading and Language Conventions in Grade 5 (15%, 37% respectively). CONCLUSIONS: Our findings contribute to growing evidence that vegetation around primary schools is associated with higher achievement in Literacy and Mathematics, with partial mediation by vehicle emissions. Future studies should conduct on-site measurement of vehicle emissions and audit vegetation around schools to confirm findings and inform urban/school planners and school leaders on designing and modifying school environments to support learning.