BACKGROUND: This study investigated the relationship between long-term low-level ozone (O METHOD: Between 2010 and 2020, the Guizhou Population Health Cohort Study (GPHCS) enrolled 9280 participants, who were followed up from 2016 to 2020. A total of 7317 participants (aged 18-95 years, mean 43.70 ± 14.89 years) were included in the final analysis. Time-dependent Cox regression models were used to evaluate the hazard ratios (HRs) between O RESULTS: During a median follow-up period of 6.58 (6.25, 8.42) years, 763 participants were diagnosed with T2DM. For every 1 standard deviation (SD) increase in O CONCLUSION: This study provides robust evidence that even long-term exposure to low-level O