Digital Landscape Architecture Lab of Southeast University, Landscape Architecture Department, School of Architecture, Southeast University, Nanjing 210096, China.
Int J Environ Res Public Health. 2021 Sep 15;18(18):9705. doi: 10.3390/ijerph18189705.
Small-scale greenspaces in high-density central urban districts serve as important outdoor activity spaces for the surrounding residents, especially the elderly. This study selects six small-scale, popular greenspaces with distinct characteristics that are jointly situated along the same main urban artery in a high-density central urban district. Field investigations and questionnaires are conducted and combined with statistical analyses, to explore the spatial-temporal distribution and influencing factors of PM2.5 concentrations in these greenspaces. The study finds that the air quality conditions in the sites are non-ideal, and this has potential negative impacts on the health of the elderly visitors. Moreover, the difference values of PM2.5 concentrations' spatial-temporal distributions are significantly affected by vehicle-related emissions, which have significant temporal characteristics. PM2.5 concentration is strongly correlated with percentage of green coverage ( = 0.82, < 0.05), degree of airflow ( = -0.83, < 0.05), humidity and comfort level ( = 0.54, < 0.01 and = -0.40, < 0.01 respectively). Meanwhile, the sites' "sky view factor" is strongly correlated with degree of airflow ( = 0.82, < 0.05), and the comfort level plays an indirect role in the process of PM2.5 affecting crowd activities. Based on this analysis, an optimal set of index ranges for greenspace elements which are correlated with the best reduction in PM2.5 concentrations is derived. As such, this research reveals the technical methods to best reduce their concentrations and provides a basis and reference for improving the quality of small-scale greenspaces in high-density urban districts for the benefit of healthy aging.
高密度中心城区的小规模绿地是周围居民，尤其是老年人重要的户外活动空间。本研究选取了六个具有鲜明特色的小规模、受欢迎的绿地，它们共同位于高密度中心城区的同一条主要城市动脉沿线。通过实地调查和问卷调查，并结合统计分析，探讨了这些绿地中 PM2.5 浓度的时空分布及其影响因素。研究发现，这些地点的空气质量状况不理想，这可能对老年游客的健康产生负面影响。此外，PM2.5 浓度时空分布的差值值受与车辆相关的排放物影响显著，具有明显的时间特征。PM2.5 浓度与绿地覆盖率（ = 0.82，<0.05）、空气流通程度（ = -0.83，<0.05）、湿度和舒适度（ = 0.54，<0.01 和 = -0.40，<0.01 分别）呈强相关。同时，这些地点的“天空视角系数”与空气流通程度呈强相关（ = 0.82，<0.05），舒适度在 PM2.5 影响人群活动的过程中起着间接作用。在此基础上，得出了一组与 PM2.5 浓度最佳降低相关的绿地要素的最佳指标范围。因此，本研究揭示了最佳降低其浓度的技术方法，为改善高密度城市区小规模绿地质量，促进健康老龄化提供了依据和参考。
