By Linda Carroll

(Reuters Health) – Elementary schools with the greatest proportions of poor children may have the least amount of shade in their schoolyards where kids spend their recess, a new U.S. study finds.

Researchers analyzing available shade in St. Louis elementary schools found a steady decrease in the amount of shade, especially from trees, with an increase in the number of children who qualified for subsidized lunches, according to the results in JAMA Dermatology.

And that means poor kids are more exposed to the sun’s damaging rays, said the study’s lead author, Jolee Potts, a medical student at Washington University School of Medicine in St. Louis.

“Shade on playgrounds is important because UV exposure is cumulative – meaning as you age, all of the sun exposure over your entire life adds up and contributes to your risk of getting skin cancer, including melanoma,” Potts said in an email. “About half of lifetime UV exposure occurs in childhood, making this time especially important for prevention. Adequate playground shade can also help immediately protect kids that are especially susceptible to the sun, including those with very fair skin, kids with conditions like lupus, or kids taking medications that make them more sensitive to the sun.”

Potts and coauthor Dr. Carrie Coughlin analyzed data from 174 elementary schools, including 139 in St. Louis County and 35 in the city of St. Louis.

They used subsidized school lunches as a proxy for household income and socioeconomic status. Their data on free and reduced-price lunches came from the Missouri Department of Elementary and Secondary Education’s Comprehensive Data System.

To estimate available shade for each school, the researchers turned to Google Earth Pro. With the satellite data and imagery provided by that software, they were able to visualize and measure the area of each school playground along with the shade cover from trees and shade structures.

“Trees provided 97% of the shade we measured and stand-alone structures made to provide shade made up the other 3%,” Potts said. “This is important because trees lose their leaves in the fall, but the sun emits dangerous UV rays during every season.”

Among the 174 schools, the average amount of shaded playground was 7.6%. Half of schools had 5.6% or less shaded area and 21 schools had no shade at all. The proportion of children getting subsidized lunches at individual schools ranged from 6.1% to 94.9%.

The researchers found that the amount of shade in playgrounds decreased as the number of children receiving subsidized lunches increased. More specifically, there was a decrease of approximately 22 square feet of shade with every 1% increase in the proportion of children getting a subsidized lunch.

The lack of shade adds to a long list of disparities between high- and low-income school districts, said Joyce Pressley, an associate professor of epidemiology and health policy at the Mailman School of Public Health at the Columbia University Medical Center in New York City.

“Higher-income school districts have better playground equipment, more updated playground equipment and more appropriate groundcover,” Pressley said. “The fact that there is not as much shade in the lower-income school districts is not surprising.”

The dearth of trees in many school playgrounds is unfortunate because “trees also are important for heat moderation in the summer,” Pressley said. “And that can make a difference in terms of dehydration and heat exposure.”

School districts that want to improve the situation by adding greenery might consider partnering up with forestry programs and public gardening clubs, Pressley said. “There are ways this could be done less expensively,” she added.

SOURCE: JAMA Dermatology, online August 14, 2019.