An theoretical and empirical evaluation of confounding mechanisms in the analysis of the health effects associated with long-term exposure to air pollution, with a case-study example using the UK Biobank cohort. This repository stores the updated R code to reproduce the analysis presented in the article: Vanoli J, et al. Confounding issues in air pollution epidemiology: an empirical assessment with the UK Biobank cohort. International Journal of Epidemiology. 2025;54(5):dyaf163. DOI: 10.1093/ije/dyaf163.