Human-greenspace interactions with outdoor air: Landscape metric and PLS-SEM approach

Air pollution poses a significant global challenge, impeding the realization of sustainable development goals, especially in urban areas. Within built environment, the intricate interplay of human and greenspace primarily influences outdoor air quality. Therefore, to facilitate effective urban planning, the study investigates their complex interactions during the wet (May to October) and dry (November to April) seasons. This research employs landscape metrics to assess greenspace configurations within various buffers around 73 in-situ air quality moniroting stations accross Taiwan. These landscape metrics, anthorpogenic variables were utilized to construct the dimension of greenspace (GS) and anthoropogenic component (AC), respectively. Recorded air quality data were used to define the dimensions of outdoor air (OADs), encompassing air temperature (TEMP), wind speed (WS), relative humidity (RH), particle pollutant (PP), gaseous pollutant (GP), and OZONE. Subsequently, Partial Least Squares - Structural Equation Modeling was employed to explore the hypothesized relationships among these eight dimensions for each buffer and season. Results show that the AC exerts a more pronounced influence on the OADs compared to the GS. The GS shows greater effectiveness in mitigating the PP than the GP, while the AC substantially amplifies the GP during the two seasons. The GS and AC exhibit contrasting effects on the TEMP, RH, and GP. The GS exclusively affects the PP, while its effects on the OZONE and WS are insignificant during both seasons. Conversely, the AC has a negligible effect on the PP, but significantly impacts the OZONE, and WS. Through the GS, the AC indirectly influences the RH, PP, and GP during the two seasons, along with the TEMP during the wet season. Notably, the seven landscape metrics are identified for the GS, providing potential indicators for urban green planning to maximize its ecosystem services.