Effects of Air Pollutants on Mortality of Chronic Kidney Disease Patients with Green Spaces Exposure: A Large Observational Study

With increasing air pollution, the association between green space exposure and health outcomes is a global health concern. The relationship between air pollution and the survival of patients with chronic kidney disease (CKD) who are exposed to residential greenness is yet to be elucidated. This study aimed to determine this relationship in Seoul between 2002 and 2015. A time-varying survival analysis was conducted to investigate the association between long-term exposure to air pollutants and mortality in 29,602 patients with CKD living in residential environments with small and large green infrastructure. The low and high index groups were defined using continuous and percentile thresholds of the satellite data—the derived average Normalized Difference Vegetation Index within 250 m and 1,250 m of residence, respectively. During the observation, 3,863 (14%) deaths occurred. The effect of air pollution exposure on mortality was worse in the low index group than in the high index group. Particularly, exposure to SO 2 was associated with increased mortality risk, regardless of the greenness threshold. Consistent results were observed in co-pollutant models. High greenery exposure significantly reduced the risk of air pollution related mortality. Our results emphasize the need for creating environmental infrastructures that include green spaces.