Speaker
Description
The intensifying global warming, coupled with urban heat island phenomena, have brought a wide range of health issues related to humid heat exposure, particularly in densely populated urban areas of tropical and subtropical regions (Zhang et al., 2023). Our prior research has demonstrated that humid heat exposure significantly jeopardizes adolescents’ sleep health, with wet bulb temperatures ranging from 25-30 °C causing a three to sixfold increase in the risk of sleep disorders, markedly higher than when considering dry bulb temperatures alone (Gao et al., 2025). These findings underscore the urgent need for planning interventions.
Urban Green Space (UGS) mitigates heat in surrounding areas through enhanced evaporation, provision of shade, and improved air circulation (Gunawardena et al., 2017). Trees, grass, and soil can absorb excess heat and moisture, regulating air temperature and humidity, as demonstrated a crucial pathway to reduce urban humid heat in a recent global scale work (Yang et al., 2024). While several studies have examined specific UGS types and their cooling effects in relation to landscape features and neighboring land uses (Aram et al., 2019), few have assessed the cooling potential of UGS in conjunction with public health benefits or explored the spatial mismatches from a regional scale, hampering effective planning.
Our study utilized survey data from over 100,000 adolescents across six cities in China’s Greater Bay Area, alongside land use data (30m resolution) and monthly climate data (1km resolution). We applied a random forest method to develop an atmospheric temperature prediction model, incorporating land use, NDVI, and various climate indicators, achieving an average accuracy exceeding 0.9. We evaluated four distinct planning approaches for introducing new UGS: expanding existing large UGS, expanding existing small UGS, establishing new large UGS, and creating new small UGS. All proposed UGS were based on patches that were bare ground during the survey period, with their average NDVI values equal to the existing UGS. We integrated simulated scenarios with the temperature prediction model and linked these to a nonlinear regression model analyzing sleep disorder risks. Our findings indicated that adding approximately 2.3 square kilometers of new UGS significantly reduced the risk of sleep disorders for about 50% of the sampled adolescents. Expanding existing large UGS benefited the largest number of samples, while expanding existing small UGS yielded the lowest Gini coefficient for sleep disorder risks across all samples, indicating the most equitable outcomes. Establishing new small UGS had the least impact on cooling and health benefits, likely due to their location in suburban areas.
The four scenarios we analyzed highlight the common trade-offs between economic and social factors in urban planning. In China, the hierarchical breakdown of land use indicators at the provincial, municipal, and county levels serves as a widely utilized policy tool often accompanied by mandatory UGS requirements (Lin et al., 2023). Selecting small, low-value bare land patches to meet these requirements is cost-effective and minimizes social issues; however, it may lead to inefficient resource use considering climate and public health benefits. Conversely, expanding existing large UGS in city centers incurs high development costs due to premium land values, presenting potential challenges. As public health and its equity in the planning and development of UGS has often been neglected in past practices, it is essential to prioritize these factors to attain more effective and sustainable outcomes.
References
Aram, F., García, E. H., Solgi, E. & Mansournia, S. (2019). Urban green space cooling effect in cities. Heliyon, 5(4).
Gao, Y., et al. (2025). Humid heat’s nonlinear influence on adolescents’ sleep disorder: Evidence from tropical urban areas. Working Paper.
Gunawardena, K. R., Wells, M. J. & Kershaw, T. (2017). Utilising green and bluespace to mitigate urban heat island intensity. Science of the Total Environment, 584, 1040-1055.
Lin, J., Gao, Y. & Zhao, Y. (2023). Exploration of national territory spatial governance from the perspective of spatial development rights. Journal of Natural Resources, 38(6), 1393-1402. [in Chinese]
Sun, Y., Xie, S. & Zhao, S. (2019). Valuing urban green spaces in mitigating climate change: A city-wide estimate of aboveground carbon stored in urban green spaces of China's Capital. Global Change Biology, 25(5), 1717-1732.
Wu, Y., et al. (2025). How small green spaces cool urban neighbourhoods: Optimising distribution, size and shape. Landscape and Urban Planning, 253, 105224.
Yang, Y., et al. (2024). Regulation of humid heat by urban green space across a climate wetness gradient. Nature Cities, 1-9.
Zhang, K., et al. (2023). Increased heat risk in wet climate induced by urban humid heat. Nature, 617(7962), 738-742.
| Keywords | Urban Green Space; Sleep Disorder; Cooling Effect; Social Equity |
|---|---|
| Best Congress Paper Award | Yes |
