The Impact of Wildfire Smoke on Acute Cardiovascular and Respiratory Illness in the US

Escalating wildfire frequency increases population exposure to wildfire smoke. To evaluate the association between wildfire-specific particulate matter (PM_2.5) and acute health impacts a retrospective cohort study was conducted utilizing National COVID Cohort Collaborative health records from 109,012 patients across 58 US health systems from 2020 to 2021. County-level wildfire-specific PM_2.5 concentrations were estimated using a fire emissions database and chemical transport modeling. Generalized linear mixed-effects models were used to analyze the association between weekly county-level wildfire-specific PM_2.5 exposure (up to 50 μg/m³) and hospital encounters for a series of cardiac, pulmonary, obstetric and neonatal outcomes. Statistically significant increases in weekly encounters per county of residence were observed for every 10 μg/m³ rise in weekly maximum wildfire-specific PM_2.5 for acute myocardial infarction (0.084, 95% CI, 0.023-0.146), cardiac arrest (0.011, 95% CI, 0.001-0.021), heart failure (0.083, 95% CI, 0.024-0.142), atrial fibrillation (0.115, 95% CI, 0.014-0.216), COPD exacerbation (0.034, 95% CI, 0.001-0.066) and pulmonary embolism (0.048, 95% CI, 0.003-0.094). COVID infection status was not found to have a modifying effect on these relationships. There was no significant increase in COVID pneumonia admissions in response to increasing wildfire smoke. These findings demonstrate quantifiable increases in acute cardiorespiratory morbidity associated with wildfire smoke exposure.