Dangerously hot playground temperatures explored by researcher

The sun.

Especially in the South and Southwest, where 90- and 100-degree air temperatures are the norm for several months of the year, unshaded playground equipment can reach temperatures that can cause burns to children. Yet according to one Texas Tech University atmospheric science researcher, minimal rules exist in the governing body's guidelines to mitigate this.

That's why a pilot study and paper published this week could be the first step toward improving safety at playgrounds across the country with a simple, obvious solution -- providing a little shade. This 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 in terms of heat exposure and burning potential."

Vanos, along with professors Ariane Middell and Benjamin Ruddell at Arizona State, studied a playground in Gilbert, Arizona, a suburb of Phoenix, that 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."

Collecting data Temperatures were taken from two different sources. The first involved an airplane flying over the playground using remote sensing equipment to take readings at both the neighborhood and microscale resolutions to provide a thermal infrared spectrum. The second involved researchers traveling the neighborhood on a golf cart with a full suite of meteorological instruments and using a hand-held infrared thermometer to measure surface temperatures up close, or in situ.

The in situ readings were necessary because the airborne data sensing equipment is only able to measure the temperatures of things it can see from the air with coarse resolution. Aircraft readings were unavailable for items that might have been hidden under shade, whether it was natural or artificial.

"We got all the temperatures, the slide, the handle bars, different playsets, all the various surfaces, and tried to get them in the sun and in different types of shade to see what the influence of shade was," Vanos said. "Then we related it to the type of shade, how much of the sky is viewed by the surface, how much energy from the sun is hitting the surface, and the material and type of equipment. What you expect is, in any shade situation, the surface temperature will be equal to the air temperature in most situations. We used that as a reference point to see how far away from the air temperatures objects were."

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 from the boiling point of water. In the shade of a tree however, 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 material of which the slide 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."

Implementing the solution The solution sounds so simple -- shade. Whether it's from natural sources such as trees or construction shade sails over playground equipment, such as there are in Phoenix, doing so can dramatically improve the safety of playgrounds and reduce the burning potential for children.

Yet there are minimal guidelines for parks and recreation directors to follow on this issue. Vanos, became a Certified Playground Inspector with the NPPS over the summer to understand how inspectors were trained on safety issues and whether there was information in training literature about surface temperatures and materials when it comes to shade. There was not.

"There are dangers in a playground that are more important than just burning hands and feet and all that, but heat stress is a big issue, too," Vanos said. "Kids are so much more vulnerable than adults for burning and overheating, and understanding heat stress is a big issue. Kids get overlooked a lot in that sense."

This is where Vanos' work in climate change comes into effect. 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.

Not all playgrounds will need year-round shade as the one in Gilbert, however. In Lubbock, Vanos said, shade would be necessary for many months, but the temperature variation of the South Plains would necessitate any artificial shade be removable to allow sunshine to blanket the playground during the cold or winter months.

Deciduous trees can provide shade in the summer and shed their leaves in the winter, providing the same effect. However, permanent artificial shade makes more sense in Phoenix, with deciduous trees for places that get cold in the winter, such as Chicago or New York.

Vanos and her fellow researchers also would like to expand the study in order to develop an algorithm using satellite imagery to predict what the temperature of playground surfaces or equipment will be at certain times of day in various climates in order to increase safety measures and awareness.

Above all else, with the concern about childhood obesity in the country, the objective is to make playgrounds as safe as possible so children will utilize them more to exercise not only their bodies but their minds as well.

"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."