Atmospheric Exposures and Cardiovascular Mortality in U.S. Counties: Formaldehyde and Wet-Bulb Temperature as Leading Predictors

Cardiovascular disease (CVD) is the leading cause of mortality in the United States, yet the role of atmospheric exposures as independent predictors of county-level CVD mortality remains poorly characterized. We integrated satellite-derived atmospheric data alongside socioeconomic, demographic, and livestock predictors across 24,487 county-year observations in the contiguous United States (2012–2019) and applied an XGBoost model with SHAP-based interpretability to identify the leading predictors of county-level CVD mortality (Test R2 = 0.712, RMSE = 29.26 per 100,000). Three of the top ten predictors were atmospheric variables. Ambient formaldehyde exposure frequency ranked second among all 43 predictors, exceeded only by educational attainment and surpassing poverty rate. Wet-bulb temperature, which captures the combined physiological burden of heat and humidity, ranked third. Sulphate aerosol mixing ratio ranked seventh. These atmospheric predictors contributed independently of socioeconomic covariates, indicating that atmospheric exposure carries information about county-level CVD mortality risk not captured by income or education alone. Integrating atmospheric exposure monitoring into county-level CVD surveillance alongside socioeconomic indicators may improve the identification of high-risk geographies.