Particulate matter (PM2.5) and its components have been studied widely around the world and are associated with many adverse health events (e.g. cardiovascular diseases and death). Flow-mediated dilation (FMD) is a non-invasive assessment that is able to detect endothelial damage at an early stage, therefore, improving the prognosis of atherosclerotic cardiovascular disease. The current study used data from Shanghai to explore the relationship between PM2.5 and its components and FMD using multiple statistical models. The results of the analysis of 812 patients' data (age ≥ 65) suggested that as PM2.5 level rises, endothelial function reduces. Among the five PM2.5 components included in this study, black carbon was shown by both models to be the dominating factor three days post-exposure (lag3). However, results from lag4 and lag5 were inconclusive in the two models with some evidence proposing the significance of sulphate, organic matter, and ammonium. Our results are in concordance with previous literature and further prove the significance of black carbon as an individual pollutant in the atmosphere. More research is needed to confirm the role of sulphate, organic matter, and ammonium as independent pollutants in relation to health.Copyright © 2023 Elsevier B.V. All rights reserved.