Quantifying the influence of a permanent shade pavilion structure on WBGT and activity modification

Abstract Exposure to solar radiation significantly elevates heat stress during outdoor physical activity, increasing the risk of exertional heat illness. This study quantified the operational impact of a permanent, full-coverage shade pavilion on wet-bulb globe temperature (WBGT) and evaluated how shade-induced cooling modifies activity-restriction thresholds in a recreational sport setting. In Athens, Georgia, USA, we collected 309 paired sun–shade observations across a wide, representative range of humid subtropical summer conditions, comparing a sun-exposed grass field with the shaded pavilion area. WBGT values were classified according to Georgia High School Association (GHSA) heat-safety guidelines. The pavilion reduced WBGT by an estimated 4.1°C relative to the sun-exposed grass site under mean observed meteorological conditions, although the magnitude of this cooling varied with sky cover, with larger reductions under sunnier skies. In full sun, only 36% of observations fell into the no modification category, and 15% reached the most restrictive thresholds. Under the pavilion, 96% of observations required no modification, and none reached the highest activity restriction categories. These shifts in activity-modification categories translate into substantially longer durations of unrestricted activity under the pavilion, corresponding to approximately 6.7 versus 2.5 h during a standardized 9 a.m. to 4 p.m. period in shaded and sun-exposed areas, respectively. These findings demonstrate that permanent shade infrastructure can serve as an effective heat mitigation tool for schools, parks, and municipalities. The exact reductions in WBGT and associated changes in activity modification decisions, however, may vary depending on the specific shade structure design and regional climate setting.