The relationship between short-term variations of air pollutants concentrations and occurrence of ST-elevated myocardial infarction (STEMI) remains controversial. Most studies have been performed in highly polluted areas.

To analyze the association between air pollutant concentrations and admission for STEMI in a low-to-average polluted urban area.

We reviewed the medical data of the prospective SCALIM registry to identify all patients (n=631) admitted between 06/2011 and 12/2018 for STEMI in our department living in the urban area of Limoges, France, and matched them with daily and hourly averaged concentrations of air pollutants (particulate matter ≤2.5μm, PM_2.5, and ≤10μm PM₁₀, nitrogen dioxide, NO₂, and ozone, O₃) monitored in the same area. Each patient was his/her own control in this study with four control periods in the past month preceding the STEMI case.

The risk of STEMI was 30.5% higher with every 10-units PM₁₀ peak concentration increase in the two hours preceding STEMI symptoms (P<0.001). This association remained valid despite adjustment for every cardiovascular risk factor, as well as in patients without severe coronary artery disease, or those with ≤2 cardiovascular risk factors and those with history of MI. A 10-unit increase in PM_2.5 median concentration in the six hours preceding symptoms was also significatively associated with STEMI but only for patients with ≤2 cardiovascular risk factors. The O₃ and NO₂concentrations were not associated with STEMI.

The PM₁₀ pollution level was associated with the risk of STEMI, even in an area not considered as highly polluted.