The Impact of Air Pollution on Physical Functioning Decline and the Benefits of Greenness: Evidence from a Nationwide Cohort Study.

BACKGROUND: Physical functional limitations (PFLs) increase the vulnerability of adults, but their pathogenesis remains unclear.

METHODS: We conducted a nationwide longitudinal study on 62,749 records from 18,878 adults (aged ≥45) from 28 provinces in China. Risk of PFLs was assessed using a validated 9-item questionnaire. Exposure levels of air pollutants (PM10, PM2.5, and PM1) and greenness (Normalized Difference Vegetation Index, NDVI) were estimated using a satellite-based spatiotemporal model. We used the cumulative link mixed effects model to estimate the associations between short-term and long-term exposure to air pollutants, greenness, and risk of PFLs. We employed the interaction effect model to evaluate interactions between air pollutants and greenness.

RESULTS: Participants were 60.9 ± 9.6 years, with an average follow-up of 5.87 (1.65) years. Exposure to air pollution was significantly associated with a higher risk of PFLs. For instance, the OR associated with each 10 μg/m3 higher in 6-month averaged PM10, PM2.5 and PM1 were 1.025 (95% CI: 1.015- 1.035), 1.035 (95% CI: 1.018- 1.054), and 1.029 (95% CI: 1.007- 1.050), respectively. Conversely, exposure to greenness was associated with decreased risk of PFLs, the OR associated with each 1-unit higher in 1-year averaged NDVI was 0.724 (95% CI: 0.544- 0.962). Furthermore, higher greenness levels were found to mitigate the adverse effects of 1-year, 6-month, 1-month averaged PM10 and 1-year averaged PM2.5 on the risk of PFLs.

CONCLUSION: Air pollution raises the risk of PFLs while greenness could mitigate the adverse effects. Reducing air pollution and enhancing greenness could prevent physical functioning.