Long-term exposure to ultrafine particles and its association with cardiometabolic diseases, chronic obstructive pulmonary disease, and cardiometabolic biomarkers: A cross-sectional analysis of the German National cohort (NAKO)

There is limited epidemiological evidence regarding the health effects of ultrafine particles (UFP; particles with an aerodynamic diameter of 10-100 nm). This study investigated whether long-term exposure to total particle number concentration (PNC), used as a surrogate for UFP, is associated with cardiometabolic diseases, chronic obstructive pulmonary disease (COPD), and cardiometabolic biomarkers. Our cross-sectional study included 27,390 participants of the NAKO study centers in Augsburg and Regensburg in Southern Germany. Health outcomes included self-reported, physician-diagnosed diseases such as hypertension, myocardial infarction, or COPD, alongside blood biomarkers such as glucose. Annual PNC averages for 2014 were estimated using supervised land use regression models and linked to participants' home addresses. We also obtained annual averages of further pollutants (e.g., particulate matter ≤ 2.5 µm (PM_2.5)) for 2010. We applied covariate-adjusted logistic and linear regression models to examine associations between PNC and health outcomes. Additionally, we assessed interdependencies between pollutants using two-pollutant models. Long-term exposure to PNC was associated with increased odds of hypertension and myocardial infarction, and COPD, as well as elevated glucose and leukocyte levels. For example, the odds ratio for hypertension was 1.03 (95% confidence interval: 1.01;1.05) for each increase in PNC by 1000 particles/cm³. Two-pollutant models did not substantially change the results for PNC but led to slightly wider confidence intervals. In conclusion, our study suggests that long-term exposure to PNC, as a surrogate for UFP, contributes to the risk of hypertension, myocardial infarction, COPD, and elevated blood glucose and leukocyte levels in adults. These results highlight the role of UFP within the broader mixture of ambient air pollution and underscore the need for strategies to reduce UFP exposure to prevent adverse cardiometabolic and pulmonary health effects.