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 odds ratio (OR) associated with each 10 mu g/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.Conclusions Air pollution raises the risk of PFLs, whereas greenness could mitigate the adverse effects. Reducing air pollution and enhancing greenness could prevent physical functioning. Graphical Abstract