Short‐Term Associations Between Ambient Ozone and Acute Myocardial Infarction Onset Among Younger Patients: Results From the VIRGO Study

The association between ambient ozone (O₃) and acute myocardial infarction (AMI) onset is unclear, particularly for younger patients and AMI subtypes. This study examined the short-term association of O₃ with AMI onset in patients aged 18-55 years and explored differences by AMI subtypes and patient characteristics. We analyzed 2,322 AMI patients admitted to 103 US hospitals (2008-2012). Daily maximum 8-hr O₃ concentrations estimated using a spatiotemporal deep learning approach were assigned to participants' home addresses. We used a time-stratified case-crossover design with conditional logistic regression to assess the association between O₃ and AMI, adjusting for fine particulate matter, air temperature, and relative humidity. We conducted stratified analyses to examine associations for AMI subtypes and effect modification by sociodemographic status, lifestyle factors, and medical history. An interquartile range (16.6 ppb) increase in O₃ concentrations was associated with an increased AMI risk at lag 4 days (odds ratio [OR] = 1.21, 95% confidence interval [CI]: 1.08-1.34) and lag 5 days (OR = 1.11, 95% CI: 1.00-1.24). The association was more pronounced for non-ST-segment elevation AMI and type 2 AMI compared with ST-segment elevation AMI and type 1 AMI, respectively. Stronger O₃-AMI associations were observed in non-Hispanic Blacks than in non-Hispanic Whites. Our study provides evidence that short-term O₃ exposure is associated with increased AMI risk in younger patients, with varying associations across AMI subtypes. The effect modification by race/ethnicity highlights the need for population-specific intervention strategies.