Impact of Air Pollution on Myocardial Infarction Incidence in a City with Fair Air Quality - Results from the EPIC-MI (Environmental Pollution and IncidenCe of Myocardial Infarction) Study

Recent research has shown potential associations between air pollution and cardiovascular diseases. However, there is still a lack of data, especially in cities with relatively low pollution levels and among young age populations. The EPIC-MI Study aims to explore whether, even in a city boasting fair air quality such as Bremen, Germany, there is a noticeable impact of air pollution on the risk of cardiovascular events in an urban environment. Additionally, an analysis of different age groups will be performed to further understand these associations.

 

All consecutive patients diagnosed with acute myocardial infarction (MI) and admitted to the heart center in Bremen from 2013 to 2023 were included. Air pollution data, encompassing monthly averages of PM10, PM2.5, NO₂, O₃, SO₂, and CO, were meticulously collected from five strategically positioned monitoring stations. Poisson regression was employed to analyze the associations between these pollutants and MI incidence, adjusting for climate parameters such as relative humidity, temperature, precipitation, and sunshine duration.

Over a decade, analysis of 19 262 MI cases demonstrated a significant independent association between monthly average MI incidence and pollutant concentrations within the same month, even after adjusting for climate parameters (Figure 1). CO (p = 0.009), O₃ (p = 0.017) and SO₂ (p = 0.011) showed statistically significant independent effects on MI incidence. A 0.1 mg/m³ increase in CO corresponded to a 4.7% rise in MI incidence, a 10 µg/m³ increase in O₃ associated with a 3.6% increase, 1 µg/m³ increase in SO₂ and 10 µg/m³ increase in NO₂ were associated with a 5.7% and 7.1% increase in MI incidence respectively.

The Poisson regression analysis among young patients (≤55 years old) demonstrated significant independent associations between monthly average MI incidence and O₃ (p = 0.035), SO₂ (p = 0.033), and NO₂ (p = 0.002) concentrations, while no significant associations were found for CO and PM10. Conversely, older patients (>60 years old) exhibited statistically significant independent associations between monthly average MI incidence and CO (p = 0.02) and SO₂ (p = 0.03) concentrations, with no significant associations observed for O₃, PM10 and NO₂.

In the analysis of seasonal variations in air pollution levels and MI incidence, notable distinctions emerged. During summer significant reductions of air pollutant levels were observed compared to winter with significantly lower mean levels of PM10 (15.76 µg/m³ vs. 19.09 µg/m³, p = 0.01), PM2.5 (9.43 µg/m³ vs. 13.69 µg/m³, p < 0.001), SO₂ (1.50 µg/m³ vs. 1.72 µg/m³, p = 0.21), NO₂ (14.30 µg/m³ vs. 22.81 µg/m³, p < 0.001) and CO (0.16 vs. 0.26, p = 0.01). Concurrently, a 7.8% reduction in MI incidence was found during summer compared to winter (150.93 vs. 163.67, p = 0.02).

The study demonstrates an enduring influence of air pollutants on cardiovascular events, even in a city with fair air quality, such as Bremen. The reduction in MI cases observed during the summer season 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.

 

Figure 1: Association between the monthly average myocardial infarction incidence and pollutant concentrations within the same month.