Ambient air pollution and glaucoma among middle-aged and older adults in China: Evidence from the China health and retirement longitudinal study.

Glaucoma is a leading cause of irreversible blindness globally. While age and genetics are established risk factors, environmental exposures like air pollution are increasingly implicated. This study investigated the association between long-term exposure to various ambient air pollutants and the risk of glaucoma in a middle-aged and older Chinese population. Data from the China Health and Retirement Longitudinal Study (CHARLS) were analyzed, including information from 33,147 participants over four waves (2011, 2013, 2015, and 2018). Annual average concentrations of six key air pollutants, including carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), particulate matter with diameters ≤10 μm (PM10) and ≤2.5 μm (PM2.5), and sulfur dioxide (SO2), were linked to participants' residential locations using data from the China High Air Pollutants (CHAP) dataset. Among the 33,147 participants, 369 (1.11%) were identified with glaucoma. Ambient PM10 and PM2.5 concentrations in the Q2 and Q3 quartiles were associated with a higher prevalence of glaucoma in the study population. For O3 and NO2, concentrations in the Q3 quartile were associated with increased glaucoma risk. Restricted cubic spline (RCS) plots revealed potential inflection points or thresholds for the concentrations of all six pollutants, along with changes in glaucoma probability before and after these points. CO and SO2 demonstrated complex patterns of association with glaucoma probability, though neither showed significant non-linear relationships. This study provides robust evidence that long-term exposure to specific ambient air pollutants, such as PM10, PM2.5, O3, and NO2, is significantly associated with an elevated risk of glaucoma in China. Complex dose-response patterns were identified, indicating potential threshold effects. These findings underscore the importance of considering air pollution as an environmental risk factor for glaucoma and inform public health strategies for disease prevention and control.