2021 Yes https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-020-10128-2 Lanza, Kevin North America Observational Students Elementary (K-5) Temperature Humidity Health equity School physical activity Climate change adaptation Urban heat islands Temperature Playgrounds Joint-use parks Outdoor nature play In September 2019, average daily heat index ranged 2.0 °F among park sites, and maximum daily heat index ranged from 103.4 °F (air temperature = 33.8 °C; relative humidity = 55.2%) under tree canopy to 114.1 °F (air temperature = 37.9 °C; relative humidity = 45.2%) on an unshaded playground. 10.8% more girls and 25.4% more boys interacted with trees in September than in November. We found extreme heat conditions at select sites within parks, and children positioning themselves under trees during periods of high heat index.