Risk-benefit analysis of the association of ambient fine particulate matter pollution and physical activity with age-related cataract: A prospective cohort study

The aim of this study was to examine the associations of fine particulate matter (PM2.5) and physical activity (PA) with age-related cataract and its subtypes, and to explore potential interactions between PM2.5 and PA. A total of 291,627 participants enrolled in the UK Biobank cohort during 2006–2010 was included. The annual mean concentration of PM2.5 at each participant's residential address was estimated using Land Use Regression models. PA was measured using the International Physical Activity Questionnaire. Cox proportional hazards model was used to examine the associations of PM2.5 and PA with incident age-related cataract, and to assess their interactions on additive and multiplicative scales. We identified 12,826 incident cases of age-related cataract, including 7686 cases of nuclear cataract and 5140 cases of non-nuclear cataract. Higher PM2.5 exposure was associated with a higher risk of age-related cataract [HR = 1.140; 95% CI: 1.105, 1.177; per 1 μg/m3 increase], and the association was stronger for non-nuclear cataract than for nuclear cataract. There was a negative association between PA and cataract [HR = 0.925; 95% CI: 0.879, 0.974; comparing high to low level]. No clear evidence of the interactions between PM2.5 and PA was found. Our findings indicated that high PM2.5 exposure and low levels of PA were independently associated with increased risks of incident age-related cataract.