Among 9,591 participants, a 0.1 unit increase in residential greenness was associated with a 32% reduced risk of .
Higher levels of residential greenness are linked to a significantly reduced risk of both distance and .
For every 10 µg/m³ increase in particulate matter (PM), the risk of distance visual impairment increases by 60%.
Increased exposure to nitrogen oxides (NO) is associated with a higher risk of visual impairment.
The negative effects of air pollution on visual impairment risks are lessened in areas with greater residential greenness.
Air pollution plays a mediating role in the relationship between residential greenness and visual impairment.
Simplified
OBJECTIVE: The aim of this study was to investigate the associations between residential greenness, air pollution (PM, PM, and NO), and the risk of visual impairment in Chinese middle-aged and elderly adults. 2.5 10 2
METHODS: The data were used from the China Health and Retirement Longitudinal Study (CHARLS), focusing on adults aged 45 years and older. Exposure to residential greenness was assessed using the (NDVI), while air pollution exposure (PM, PM, and NO) was estimated from the ChinaHighAirPollutants dataset. Visual impairment was self-reported and categorized as (DVI) and (NVI). Cox proportional hazards models were applied to investigate the associations between residential greenness, air pollution, and visual impairment. Furthermore, we investigated the potential modification and mediation relationship between residential greenness, air pollution and visual impairment. 2.5 10 2
RESULTS: A total of 9,591 participants were included in this study. During a 7-year period, 2,650 cases of DVI and 3,130 cases of NVI were identified. In the single exposure model, a higher level of residential greenness was associated with a significantly reduced risk of both DVI and NVI. Specifically, for every 0.1 unit increase in NDVI, the hazard ratio (HR) was 0.68 (95%CI: 0.65,0.71) for DVI, and 0.67 (95%CI: 0.64,0.69) for NVI. Conversely, exposure to air pollution was positively associated with increased risks for both DVI and NVI. For each 10 µg/mincrease in PM, the HR was 1.60 (95%CI: 1.56,1.65) for DVI and 1.64 (95%CI: 1.60,1.69) for NVI. Similarly, PMand NOexposure showed elevated risks with HR of 1.28 (95%CI: 1.27,1.30) and 1.73 (95%CI: 1.62,1.85) for DVI, and 1.30 (95%CI: 1.28,1.32) and 1.82 (95%CI: 1.72,1.94) for NVI, respectively. The multiple exposure model also showed significant association between residential greenness, air pollution and visual impairment risk. Additionally, the adverse effects of PM, PM, and NOwere attenuated in areas with the highest levels of residential greenness. Mediation analysis revealed that air pollution mediated a significant portion of the association between residential greenness and visual impairment. 3 2.5 10 2 2.5 10 2
CONCLUSION: This study suggests that increased residential greenness may reduce the risk of visual impairment, partially by mitigating air pollution exposure. These findings highlight the environmental benefits to improve air quality and enhance green spaces, thereby promoting visual health in aging populations.
Key numbers
0.68
Decrease in Risk of
Hazard ratio for per 0.1 unit increase in
1.60
Increase in Risk of with PM
Hazard ratio for per 10 µg/m³ increase in PM
1.64
Increase in Risk of with PM
Hazard ratio for per 10 µg/m³ increase in PM
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Declarations. Ethics approval and consent to participate: The data used in this study were approved by the Biomedical Ethics Review Committee of Peking University (Approval Number: IRB00001052-11015). Written informed consent was obtained from all participants. All methods in this study on humans described in the manuscript were performed in accordance with national law and the Helsinki Declaration of 1975. Competing interests: The authors declare no competing interests.
