The health risk reduction of PM_2.5 via a green curtain system in Taiwan

Green infrastructure can release oxygen, and capture particulate matter (PM), which can improve urban air quality and heat islands. This study aims to develop a green curtain to reduce PM_2.5 through three-dimensional greening with a low preparation cost, low maintenance cost, high efficiency, and readily replaceable types. In this study, a green curtain system (GCS) was installed on a balcony with three plants, Chlorophytum comosum, Nephrolepis exaltata, and Nephrolepis pendula (Raddi) J. Sm, Another balcony without GCS was used as a control group for the study. The experiment demonstrated the efficacy of Greening Curtain Systems (GCS) on balconies in reducing PM_2.5 exceedance time, particularly with 60 pots containing a mix of three plants, where Chlorophytum comosum showed notable effectiveness as a single protective plant. Leaf capture efficiency remained relatively unchanged even after 17 days without washing, attributed to the humidity of winter evenings and the evapotranspiration effect of the plants. Additionally, a health risk assessment, employing an attributable risk approach, was conducted to validate the effectiveness of PM protection measures in lowering occupants' health risks. Utilizing data on the correlation between all-cause mortality risk in individuals aged 65 and above and considering the delayed impact of atmospheric factors on human health, we employed a delayed nonlinear model to explore the exposure-response relationship. The results revealed that GCS successfully reduced the duration of high PM_2.5 concentration during air pollution episodes by 15–18 μg/m³, thereby mitigating potential health risks associated with successive air pollution episodes.