Does air pollution impact myocardial infarction incidence even in a city with fair air quality? Results from the EPIC-MI (Environmental Pollution and IncidenCe of Myocardial Infarction) Study

Abstract Background In light of recent research highlighting the potential association between air pollution and cardiovascular diseases, there remains a gap in data, particularly in cities characterized by relatively low pollution levels. The EPIC-MI Study endeavors to explore whether, even in a city boasting fair air quality such as our city, there exists a discernible impact of air pollution on the risk of cardiovascular events within an urban setting. Methods We analyzed all consecutive acute myocardial infarction (MI) patients admitted to our city heart center from March 2013 to December 2022. Air pollution data were meticulously gathered from 5 strategically positioned monitoring stations. Utilizing Poisson regression, the associations between these pollutants and the incidence of MI was analyzed. We also investigated the impact of pollution exceedance days and COVID-19 lockdown periods on MI incidence. Results Over nearly a decade, 18.798 MI cases were analyzed. The Poisson regression model revealed a significant independent association between the monthly average MI incidence and pollutant concentrations within the same month. Statistically significant independent effects were observed for CO (p<0.01), O₃ (p=0.03), SO₂ (p<0.01), and relative humidity (p<0.01) on MI incidence (Figure 1). Exceedance days were associated with a significant upswing in daily MI incidence. The MI incidence increased by 3.3% when PM10 exceeded 25 µg/m³ on the same day (5.19 ± 2.49 vs. 5.36 ± 2.50, p=0.03) and remained elevated over three days (5.19 ± 1.42 vs. 5.34 ± 1.46, p<0.01). For PM2.5, there was a 4.2% increase when exceeding 20 µg/m³ on the same day (5.20 ± 2.49 vs. 5.42 ± 2.52, p=0.02) and still elevated over three days (5.20 ± 1.42 vs. 5.40 ± 1.47, p<0.01). During the COVID-19 lockdown periods, a significant decrease was observed in air pollutant levels compared to non-lockdown years within the same timeframe (Figure 2). PM2.5 (9.89 µg/m³ vs. 12.76 µg/m³, p=0.02), PM10 (15.26 µg/m³ vs. 18.7 µg/m³, p<0.01), SO2 (1.16 µg/m³ vs. 1.77 µg/m³, p<0.01), and NO2 (14.42 µg/m³ vs. 19.53 µg/m³, p<0.01) exhibited significant reductions. Concurrently, a 22.5% reduction in daily MI incidence was observed compared to non-lockdown years within the same timeframe (4.16 vs. 5.37, p<0.01). Conclusion The study demonstrates an enduring influence of air pollutants on cardiovascular events, even in a city with fair air quality, such as our city. Elevated concentrations of air pollutants, especially on days with excessive levels, were significantly associated with an increased incidence of MI. The reduction in MI cases observed during the COVID-19 lockdown period underscores the potential cardiovascular benefits associated with improved air quality. These findings emphasize the importance of sustained efforts to mitigate air pollution for the enhancement of cardiovascular health in urban environments.