Jennifer Vanos with the Climate Science Center led the team that found very hot temperatures on playgrounds.
In warmer climates, where 90- and 100-degree air temperatures are the norm for several months of the year, unshaded playground equipment can reach temperatures that cause burns to children. But a pilot study and paper published this past fall could be the first step toward improving safety at playgrounds throughout the country with a simple, obvious solution – providing a little shade.
The study is from Jennifer Vanos, an assistant professor in the atmospheric science group in the Department of Geosciences and a faculty associate with the Texas Tech Climate Science Center, and her colleagues at Arizona State University.
“We need to provide comfortable spaces, especially in urban areas so kids can go out and play,” said Vanos, whose area of specialty is the impact of weather and climate on humans. “During the summer, those spaces often aren't available. But we were able to show that even on extremely hot days, a park that had a shade sail was safe to play in considering heat exposure and burning potential.”
Vanos, along with Arizona State professors Ariane Middel and Benjamin Ruddell, studied a playground in the Phoenix suburb of Gilbert, Arizona, which had areas of sun where surface temperatures reached near-boiling point levels but where shade made a significant difference.
The study showed even a little shade on the equipment, whether by an artificial shade sail or by natural means such as trees, had a huge impact on the safety and comfort of not only the playground equipment but also the natural and artificial surfaces on which the playgrounds were constructed.
“This is all probably common sense to a lot of people,” Vanos said. “Essentially we're showing by just providing the mechanism of shade in the playground it brought temperatures into safe values so kids could actually play. In hotter temperatures they're not going to play and have a high likelihood of burning their skin.”
What Vanos and her colleagues found was striking. For example, the rubber surface on which the playground was constructed, which was soft to cushion falls and colored green and black, was recorded at 87.2 degrees Celsius in the sun at noon, less than 13 degrees below the boiling point of water. In the shade of a tree, that same surface was recorded at 42.2 C, and under the shade sail was measured at 46.7 C, both much closer to the air temperature of 41.6 C.
In terms of equipment, a green, molded plastic slide with a high-density polyethylene coating was measured at 71.7 C in the sun and 43.9 C under the tree shade. A beige-colored slide of the same material and coating was measured at 63.9 C in the sun and 40.6 C under the shade tree.
For a point of reference, the burn threshold for the slide's material is made is one minute at 60 C, five seconds at 74 C and just three seconds at 77 C, meaning a child's skin does not have to contact the surface for very long in the sun to be burned.
“There are so many reports you can find of kids burning themselves on playgrounds that are just too hot, yet there is little in the way of guidelines from the National Program for Playground Safety (NPPS),” Vanos said. “But this paper is showing there is a good solution.”
But Vanos and her colleagues haven't relied just on temperatures taken at the state.
Since the paper was published, further research has focused on taking microscale data from the children themselves. Vanos said an additional step has been taken where researchers assess how microscale weather variables, such as temperature or radiation, can impact a child's thermal comfort level, i.e., how hot or cold they are.
Another pilot study has bene undertaken collecting “individually experienced exposures” of temperatures and ultraviolet-b (UVB) radiation and children's heart rates while playing, and the impact that surface type and shade cover have on children's exposures to both parameters.
“With our microclimate weather station, we get a sense for the full playground's environment, but with the personal sensors, we can see the fine-scale environment experienced by each and every child,” Vanos said. “The data can help provide the evidence base needed for designers of playgrounds to use when thinking about the impacts of shade, surface type and overall weather parameters on children's activity levels, health, well-being and behavior.”
With the continued warming of the planet, temperatures are only going to rise, making playgrounds hotter and the need for shade greater.
“Urban climates also warm with growing urban areas due to the urban heat island effect. That's cumulative with the increasing temperature due to climate change,” Vanos said. “We need to be able to make sure kids can still play and not be stuck inside all the time, especially in warmer climates, because we know it happens. Providing shade is something Lubbock could easily do. We've started this pilot study in Phoenix because that's the hottest city in the U.S., but we want to expand it to other cities and climate zones.”
This study is one of the first done on the subject, so little information exists on playground surface temperatures. Vanos is hopeful this study begins the discussion to add heat stress and temperature-related guidelines to construction standards for current and future playgrounds.
“Playgrounds are one of the only places kids get a chance to be creative and play and be kids,” Vanos said. “To be able to freelance and play and be creative, it's a really important aspect of kids' lives. We need to make sure we provide a good environment process for that.”