Robert Hitchcock
As Southern California faces more frequent and intense heat waves, a new Chapman University study finds that some students may be spending their school days on campuses that become dangerously hot during extreme heat events. Researchers found that outdoor surfaces at some Orange County public schools reached nearly 122 degrees Fahrenheit — conditions that can affect students during recess, physical education and other activities held outdoors.
The study, published in the American Geophysical Union journal GeoHealth, led by Chapman University researchers, and funded by NASA, examined all 615 public K-12 schools in Orange County and found that campuses serving lower-income communities and larger proportions of racially and ethnically diverse students tended to experience hotter outdoor conditions. Those schools also were more uniformly hot, indicating that there may be fewer places for students to seek refuge. The findings highlight disparities in the environments where nearly 450,000 students learn and play.
Using high-resolution thermal data collected by NASA’s ECOSTRESS instrument aboard the International Space Station, researchers measured outdoor surface temperatures across school campuses during the hottest days of late summer 2023. Average campus surface temperatures exceeded 104 degrees Fahrenheit (40 degrees Celsius), with some areas reaching nearly 122 degrees Fahrenheit (50 degrees Celsius).
“We know that outdoor play and recreation are a critical part of our children’s school day, including time outdoors for recess, physical education and after-school activities,” said Gregory R. Goldsmith, Ph.D., associate professor in Chapman’s Schmid College of Science and Technology and the study’s corresponding author. “As extreme heat becomes more common, understanding which students are exposed to the hottest conditions can help inform decisions about investments in school infrastructure.”
Researchers say these temperature patterns may reflect differences in campus design and infrastructure investments, including tree canopies and other outdoor spaces providing shade, the availability of grassy areas, and the types of materials used for playgrounds, walkways and other surfaces that absorb and retain heat. For students, fewer shaded or cooler areas can mean greater exposure to extreme heat during the school day.
Researchers emphasize that the study measured surface temperatures — the heat absorbed by playgrounds, asphalt, grass and other outdoor materials — rather than the air temperature students experience. However, the satellite measurements closely tracked air temperatures recorded at local weather stations, making them a useful way to compare heat exposure across campuses.
The findings have important implications for student health and learning. Previous research has shown that extreme heat can reduce children’s physical activity during recess, increase the risk of heat-related illness and make it more difficult for students to concentrate. Because California requires elementary students to spend time outdoors for recess, many children may encounter these conditions during the hottest days of the year.
Researchers say the findings point to practical solutions, including planting more trees, expanding natural or artificial shade, increasing grass cover and using cooler pavement and playground materials. These investments could help schools create safer and more comfortable outdoor spaces as extreme heat becomes more common.
