Low-Income, Minority-Serving Public Schools in Southern California Have Disproportionately High Surface Temperatures.

Extensive evidence demonstrates that people from minority backgrounds often face unequal exposure to extreme heat and have less access to green space that can provide cooling relief. What is less clear is whether these inequities extend to students on school playgrounds, where high temperatures can affect physical health, social and emotional well-being, and learning. We paired high resolution, satellite remote sensing surface temperature data for all 615 of the public schools in Orange County, California (serving ca. 450,000 students) with data on neighborhood household income, race/ethnicity of school enrollment, distance from the coast, and Normalized Difference Vegetation Index as a measure of landscape greenness. Based on >47,000 observations from the hottest late summer days, we observed mean school surface temperatures in excess of 40°C, with temperatures at some schools reaching nearly 50°C on some days. Higher school ground surface temperatures were significantly correlated with low household income (ρ = -0.36) and racially/ethnically diverse student populations (ρ = 0.37). These same schools also exhibited less variation in temperature across their grounds, which may indicate fewer spaces for students to seek relief. Greener school landscapes were weakly correlated with lower school ground surface temperatures and this was independent of socioeconomics. Our findings provide robust evidence of links between school surface temperatures and school demographics, and they highlight the growing potential of satellite remote sensing to assess heat exposure within and across schools.