Rapid increases in nitrogen oxides are associated with acute myocardial infarction: A case-crossover study

AimsHigh concentrations of air pollutants are associated with increased risk for myocardial infarction. The European Union has defined statutory limits for air pollutants based on upper absolute concentrations. We evaluated the association between rapid changes in air pollutants and the risk of myocardial infarction independently of absolute concentrations.Methods and resultsUsing a hospital-based case-crossover study, effects of 24h changes of nitrogen oxides (NOX/2), particulate matter (PM10), and ozone on the risk of myocardial infarction was assessed in 693 patients. In the overall population, increases of NOX of more than 20 µg/m3 within 24 h were associated with an increase in the risk of myocardial infarction by up to 121% (odds ratio (OR) 2.21, 95% confidence interval (CI) 1.19–4.08). Comparably, rapid increases of NO2 of more than 8 µg/m3 tended to increase myocardial infarction risk by 73% (OR 1.73, 95% CI 0.91–3.28) while myocardial infarction risk decreased by 60% after a decrease of NO2 conce...