Researchers Recommend Planting Trees to Increase Outdoor Play Among Kids

As temperatures rise, children seek shade and spend less time in outdoor activity

Colorful school playground with blue sky in background
A strong body of research indicates adequate access to greenspace is associated with health benefits.
Kevin Lanza, PhD
Kevin Lanza, PhD

Following a study of children’s outdoor activity at three Texas elementary schools, researchers from UTHealth Houston recommend changes to playground design and play schedules. Citing evidence that children engage in less physical activity outdoors in higher temperatures and humidity, the researchers advocated for adding more shade and shifting schedules to include outdoor time during cooler hours. The study is the subject of a new paper published in December in the Journal of Physical Activity and Health.

Lead author Kevin Lanza, PhD, assistant professor of epidemiology, human genetics, and environmental sciences at UTHealth Houston School of Public Health, and his team partnered with three elementary schools and the Parks and Recreation Department in Austin, Texas, for the Green Schoolyards Project, a study looking at the impact of green features in schoolyards (trees, gardens, nature trails, etc.) on the physical activity of children. A strong body of research indicates adequate access to greenspace is associated with health benefits. In Texas, where autumn air temperatures can reach the 90s and relative humidity often exceeds 60%, outdoor activity can be uncomfortable and even dangerous.

The three elementary schools in the study serve primarily economically disadvantaged Latino households in Austin. As in communities across the United States, access to safe greenspace in Austin isn’t equal, with communities of color and low-income communities facing particularly difficult barriers.

The parks are located in areas with relatively low nature access and are comparable in terms of size and amenities, including playgrounds, multipurpose fields, running tracks, and basketball courts covered by artificial shade structures. One park, with little tree canopy cover, was designated a “low-green park,” while another, with nearly twice the shade, was designated a “high-green park.” A third park was recently updated with new green features, including planted tree saplings, a wildflower meadow, a nature trail, a rain garden and water cistern, and an outdoor classroom.

Researchers equipped third- and fourth-grade students at the schools with activity monitors and GPS devices during daily recess to measure their physical activity levels and time spent under shade. Data on air temperature, relative humidity, and available shade were also collected. Temperatures ranged from 52 to 95 F during the study, conducted in September and November 2019.

The research showed that the children spent less time in moderate to vigorous physical activity and more time under shade as the temperature increased. When temperatures reached 91 F, the children spent more time under shade than out and engaged in physical activity. In the park with the most tree canopy (the “high-green park”), children spent the most time in moderate to vigorous physical activity.

“Children are spending more time than ever indoors,” Lanza said. “They are missing out on the positive effects of nature on their physical and mental health.” 

The researchers concluded the paper with recommendations that schools and school districts schedule recess at cooler times of day and develop contingencies for extreme heat days. Additionally, researchers recommended providing shade in outdoor areas intended for physical activity, with priority given to planting trees for their ability to lower air temperatures and potentially encourage physical activity.

“Planting trees and adding other natural elements in schoolyards, and doing so in environmentally and socially responsible ways, has the opportunity to help our youth and planet,” Lanza said.

According to Texas State climatologist John Nielsen-Gammon, average temperatures in the state may rise by two to three degrees Fahrenheit over the next half-century, and The Texas Demographic Center projects the state’s population growth to exceed 26% over the same period of time. Researchers hope that continued research and planning may mitigate future challenges to greenspace access, and safe, comfortable parks for all Texans.

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