Atherosclerotic vascular disease is the main cause of mortality attributable to air pollution. This study analyzes, for the first time, the association between levels of fine particulate matter (PM2.5, particles ≤ 2.5μm in diameter) and hospital admissions and in-hospital mortality due to acute myocardial infarction (AMI) in hospitals of the Spanish National Health System.

Data on air pollution, temperature, and humidity were obtained from the Ministry for the Ecological Transition and the Demographic Challenge, covering the period from 2016 to 2021. A total of 122 National Health System hospitals were geographically matched with environmental monitoring stations located within a 10km radius. The study included 115 071 patients aged 18 years or older (mean age, 67 years; 28% women) who were discharged with a diagnosis of AMI during the study period. An autoregressive integrated moving average (ARIMA) model was applied to each hospital, and a meta-analysis was conducted to consolidate the estimates of the association between PM2.5 levels and variations in AMI hospital admissions. The association between PM2.5 pollution and in-hospital AMI mortality was analyzed using logistic regression models.

Maximum 3-day average PM2.5 levels exceeding 10μg/m3 were associated with an additional 21.9 AMI hospital admissions per 1000 (95%CI, 9.1-34.8; P<.001). Furthermore, PM2.5 levels above 25μg/m3 (3-day moving average) were associated with an increased risk of in-hospital mortality due to AMI (OR, 1.14; 95%CI, 1.07-1.23; P<.001).

This study identifies a significant association between elevated PM2.5 levels and increased hospital admissions and in-hospital mortality due to AMI in Spain, highlighting the importance of reducing air pollution as a critical factor in cardiovascular health.