Department of Urban Planning and Design, Xi'an Jiaotong-Liverpool University, Suzhou 215123, China.
Department of Public Health, Environment and Society, London School of Hygiene and Tropical Medicine, 15-17 Tavistock Place, London WC1H 9SH, UK.
Environ Int. 2024 Sep;191:108950. doi: 10.1016/j.envint.2024.108950. Epub 2024 Aug 13.
While vegetation type, population density and proximity to greenspaces have been linked to human health, what type and location of greenspace matter most have remained unclear. In this context, there are question marks over investment-style metrics.
This paper aims at establishing what vegetation type may matter most in modifying heat-mortality associations, and what the optimal buffer distances of total and specific types of greenspace exposure associated with reduced heat-related mortality risks are.
We conducted small-area analyses using daily mortality data for 286 Territory Planning Units (TPUs) across Hong Kong and 1 × 1 km gridded air temperature data for the summer months (2005-2018). Using a case time series design, we examined effect modifications of total and specific types of greenspaces, as well as population-weighted exposure at varying buffer distances (200-4000 m). We tested the significance of effect modifications by comparing relative risks (RRs) between the lowest and highest quartiles of each greenspace exposure metric; and explored the strength of effect modifications by calculating the ratio of RRs.
Forests, unlike grasslands, showed significant effect modifications on heat-mortality associations, with RRs rising from 0.98 (95 %CI: 0.92,1.05) to 1.06 (1.03, 1.10) for the highest to lowest quartiles (p-value = 0.037) The optimal distances associated with the most apparent effects were around 1 km for population-weighted exposure, with the ratio of RRs being 1.424 (1.038,1.954) for NDVI, 1.191 (1.004,1.413) for total greenspace, and 1.227 (1.024,1.470) for forests. A marked difference was observed in terms of the paired area-level and optimal distance-based exposure to total greenspace and forests under extreme heat (p-values < 0.05).
Our findings suggest that greenspace, particularly nearby forests, may significantly mitigate heat-related mortality risks.
虽然植被类型、人口密度和与绿地的接近程度与人类健康有关，但哪种类型和位置的绿地最重要仍不清楚。在这种情况下，投资风格的指标存在疑问。
本文旨在确定植被类型在改变热死亡率关联方面可能最重要的因素，以及与降低与热相关的死亡率风险相关的总绿地和特定类型绿地暴露的最佳缓冲距离。
我们使用香港 286 个地区规划单元（TPU）的每日死亡率数据和 2005-2018 年夏季的 1×1 公里网格化空气温度数据进行小区域分析。使用病例时间序列设计，我们检验了总绿地和特定类型绿地以及不同缓冲距离（200-4000 米）的人口加权暴露的效应修饰。我们通过比较每个绿地暴露指标的最低和最高四分位数之间的相对风险（RR）来检验效应修饰的显著性；并通过计算 RR 的比值来探索效应修饰的强度。
与草原不同，森林对热死亡率关联有显著的效应修饰，RR 从最高四分位到最低四分位从 0.98（95%CI：0.92，1.05）上升到 1.06（1.03，1.10）（p 值=0.037）。与最明显效应相关的最佳距离约为 1 公里，人口加权暴露的 RR 比值为 1.424（1.038，1.954），NDVI 为 1.191（1.004，1.413），总绿地为 1.227（1.024，1.470），森林为 1.227（1.024，1.470）。在极端高温下，总绿地和森林的配对区域水平和最佳距离暴露存在显著差异（p 值<0.05）。
我们的研究结果表明，绿地，特别是附近的森林，可能显著减轻与热相关的死亡率风险。
