Residential greenness, air pollution, and incident age-related macular degeneration: A prospective cohort study

Existing evidence suggests residential greenness is beneficial to human, while no research to date explored the associations of greenness with age-related macular degeneration (AMD). To evaluate the association of greenness with AMD, modification and mediation effect of air pollution, we conducted this prospective study. We constructed weighted quantile sum (WQS) index as co-exposure to nitrogen oxides (NO_x), particulate matter <2.5 µm (PM_2.5), particulate matter <10 µm (PM₁₀). Stratified Cox regression models were applied to test the effect of exposure. Effect modification of air pollution was assessed. Stratified Cox models through the indirect method and Aalen additive risk models were used in mediation analysis. Over median follow-up of 11.67 years, 4596 AMD events were ascertained. Hazard ratios (HRs) and 95 % confidence intervals (95 % CIs) of incident AMD for pollution per interquartile range (IQR) increment were 1.10 (1.04-1.16) for nitrogen dioxide (NO₂), 1.09 (1.03-1.15) for NO_x, 1.14 (1.05-1.24) for PM_2.5, 1.13 (1.05-1.21) for PM₁₀. The HR (95 % CI) of AMD associated with greenness 1000 m buffer per IQR increment was 0.91 (0.86-0.97), 300 m buffer was 0.94 (0.89-0.99). The association between greenness 1000 m and AMD was 28.59 %, 44.77 %, 35.59 %, 32.31 % and 27.08 % mediated by the decreased WQS index, NO₂, NO_x, PM_2.5 and PM₁₀, respectively. Increased greenness was associated with lower AMD incidence, and air pollution partly mediate it, which implies that interventions aimed at improving air quality and increasing greenness could have a dual benefit in mitigating AMD risk.