Cardiopulmonary hospitalization risks from wildfire-specific and non-wildfire PM_2.5 in 20 US states

Increasing wildfire activity in the US has made wildfire-specific fine particulate matter (PM_2.5) an important and growing source of air pollution, yet its long-term health impacts and relative toxicity compared with non-wildfire PM_2.5 remain unclear. Using a self-controlled design, we examine associations between 2-year average wildfire-specific and non-wildfire PM_2.5 and cardiopulmonary hospitalization risks across 20 US states during 2006-2019. Per 1 µg/m³ increase, wildfire-specific PM_2.5 is associated with significantly higher hospitalization risks for all cardiopulmonary diseases, with relative risks ranging from 10% for heart failure to 16% for asthma. In contrast, a 1-µg/m³ increase in non-wildfire PM_2.5 is associated with smaller risk elevations, ranging from 4.7% for chronic obstructive pulmonary disease to 8.5% for hypertension. Stronger associations for both wildfire-specific and non-wildfire PM_2.5 are observed among minorities, metropolitan residents, those with fewer years of education, and more deprived communities. Overall, at an equivalent concentration increase, long-term exposure to wildfire-specific PM_2.5 poses greater cardiopulmonary hospitalization risks than non-wildfire PM_2.5, underscoring wildfire smoke as a growing public health threat that requires targeted mitigation alongside conventional air quality control strategies.