Associations of air pollutant exposures with Cardio-Kidney-Metabolic syndrome in Chinese middle-aged and older adults: a cross-sectional study based on CHARLS.

BACKGROUND

Cardio-Kidney-Metabolic (CKM) syndrome is a prevalent systemic disorder, but evidence linking it to air pollution is scarce. We investigated the association between long-term exposure to multiple air pollutants and CKM syndrome severity in Chinese adults.

METHODS

In this cross-sectional study of 3,937 participants from the China Health and Retirement Longitudinal Study (CHARLS), we estimated long-term (2013-2015) residential exposures to PM₁, PM₂.₅, PM₁₀, NO₂, O₃, and SO₂. CKM syndrome was staged per American Heart Association criteria. We used ordered logistic, Weighted Quantile Sum (WQS), and restricted cubic spline regression to assess associations.

RESULTS

After full adjustment, each one-standard-deviation (SD) increase in pollutant concentration was significantly associated with higher odds of a more advanced CKM stage. The association was strongest for PM₁₀ (per 33.3 µg/m³ SD increase; OR = 1.16, 95% CI: 1.07-1.27), with significant positive associations also found for SO₂, PM₂.₅, NO₂, and O₃. The overall pollutant mixture was also positively associated with CKM progression (OR = 1.20, 95% CI: 1.02-1.41 per quartile increase in the WQS index). Older adults (≥ 60 years) and residents of eastern China were identified as particularly susceptible subgroups (P for interaction < 0.05).

CONCLUSION

Long-term exposure to ambient air pollutants, individually and as a mixture, is associated with advanced CKM syndrome in Chinese adults. Our findings identify air pollution as a critical modifiable factor and underscore the need for targeted public health interventions to mitigate the burden of this multisystem disease, especially for vulnerable populations.