LONG–TERM EXPOSURE TO PARTICULATE MATTER AND THE INCIDENCE OF METABOLIC SYNDROME AND ITS COMPONENTS: A PROSPECTIVE COHORT STUDY IN EASTERN CHINA

Objective: We conducted this prospective cohort study to investigate the associations of long–term exposure to particulate matter (PM) including of PM2.5 and PM10 with the incidence of metabolic syndrome (MetS) and its components, and explore the associations of exposure to PM2.5 and PM10 with the continuous metabolic indicators of MetS.Design and method: We utilized follow–up data collected from a cohort in Eastern China, encompassing 44,720 individuals between 2014 and 2021. Residential exposures to fine particles (PM2.5) and inhalable particles (PM10) for each participant were predicted using a satellite–based model with a spatial resolution of 1×1 km. We employed generalized estimation equations model to assess the associations of long–term PM exposures with incident MetS and its components, as well as the continuous metabolic indicators related to MetS. We also depicted the exposure–response (E–R) relationship curve to illustrate the relationship. Results: For each 10 μg/m3increase in annual average concentration of PM2.5, there was significant increases in the incidence of MetS (Relative risk: 1.173, 1.1–1.3), elevated triglycerides (TG) (1.170, 1.100–1.244), decreased high–density lipoprotein cholesterol (HDL–C) (1.182, 1.105–1.265), elevated fasting blood glucose (FBG) (2.046, 1.941–2.156), and elevated blood pressure (BP) (1.296, 1.169–1.437). The RR associated with PM10 were smaller compared to PM2.5 but still statistically significant. The analyses of continuous metabolic indicators indicated that long–term exposure to PM was positively associated with FBG and systolic BP, and inversely associated with HDL–C. Conclusions: This cohort study provides valuable evidence of the increased risk of MetS and its components associated with long–term exposure to PM in areas with high pollution levels. Furthermore, the effect of PM on elevated FBG, one of the components of MetS, is the most pronounced. Additionally, non–smokers and those with lower educational attainment demonstrated higher vulnerability to PM exposure. These associations were robust to the adjustment for gaseous pollutants. We also found significant positive associations between long–term exposure to PM2.5 and PM10 with FBG and SBP, along with a significant inversely association between long–term exposure to PM2.5 with HDL–C. These findings are valuable for revising air quality guidelines/standards and for targeted prevention for MetS.