Short-Term Exposure to Ambient Ozone and Fine Particulate Matter and Its Components Increases the Risk of In-Hospital...

Although exposure to ozone (O₃) and fine particulate matter with a diameter of ≤2.5 μm (PM_2.5) has been associated with increased cardiovascular events and hospitalizations, their association with in-hospital outcomes among patients with acute myocardial infarction remains uncertain.

A time-stratified case-crossover study was conducted using patients with acute myocardial infarction admitted to hospitals in Beijing from 2013 to 2019. Daily levels of O₃ and PM_2.5 and its components (sulfate, nitrate, ammonium, organic matter, and black carbon) were assessed. Conditional logistic regression estimated exposure-response relationships between pollutants and in-hospital death. The relative excess risk due to interaction was used to quantify interactions between O₃ and each PM_2.5 component.

O₃ exhibited a threshold effect: When the concentration on the admission day exceeded 90 μg/m³, in-hospital mortality risk increased significantly. PM_2.5 and each component showed linear exposure-response relationships. At a 2-day moving average, each 10 μg/m³ increase in PM_2.5 was associated with a 1.4% (95% CI, 0.9%-1.9%) increase in in-hospital death. Significant positive multiplicative interactions were observed between O₃ and all PM_2.5 components, with notable synergistic effects for O₃-organic matter (relative excess risk due to interaction, 0.155 [95% CI, 0.053-0.258]) and O₃-black carbon (relative excess risk due to interaction, 0.137 [95% CI, 0.033-0.240]). The effects of O₃ were stronger in summer, while the effects of PM_2.5 components were more pronounced in winter. Joint exposure resulted in a higher mortality burden than single-pollutant exposure.

Short-term exposure to O₃ and PM_2.5 components increases in-hospital mortality risk in patients with acute myocardial infarction, with synergistic effects between ozone and organic matter or O₃ and black carbon.