Environment/Climate Change
Tree Canopy Surrounding Schools and Standardized Test Scores in a Large Urban School District Mozhgan Naji* Mozhgan Naji Naji Naji Naji Naji Naji Joseph J. Zilber College of Public Health, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
Green space near schools may support academic performance through stress reduction, attention restoration, thermal comfort/air quality, and opportunities for physical activity and social interaction. Tree canopy is a specific and actionable component of green space, with existing epidemiologic evidence limited to one study reporting positive, and two reporting null associations. Given limited evidence from large, racially and economically diverse U.S. urban school districts, we studied Milwaukee Public Schools (MPS), with students from lower-income and historically marginalized racial and ethnic groups. We linked tree canopy, using the 2023 National Land Cover Database within circular buffers around school locations, with English Language Arts (ELA) and Math scores from the Wisconsin Forward Exam, for 25,709 MPS students, grades 3–8, in 2023–2024. We modeled tree canopy in quartile categories because it exhibited better fit than continuous coding and allowed flexible modeling. Multilevel linear regression models with a random intercept for school adjusted for student demographics, mobility, and child residential neighborhood socioeconomic and segregation measures. Unadjusted associations suggested positive impacts but attenuated after adjustment. For the 100m buffer, comparing the top quartile of tree canopy (9 to 20% coverage) to the bottom (0-4%) adjusted results were: ELA: β = -7.6 (95% CI: -14.9, -0.3; mean score = 1,566), and Math: β = -4.1 (95% CI: -12.0, 3.8; mean score = 1,556). Results were similar for buffers of 50, 300, and 500 m, with no clear dose-response or buffer-specific pattern. Overall, school-based tree canopy showed largely null associations with test scores, suggesting it may not benefit academic outcomes in urban settings, but limited exposure contrast or measurement limitations may also explain these findings. Future work will incorporate broader green space measures and home exposures, to inform equitable, place-based interventions.