Associations of Fine Particulate Matter Components With Acute Aortic Dissection: A Time‐Stratified Case‐Crossover Study

Background Acute aortic dissection (AAD) is among the most life‐threatening cardiovascular emergencies. Ambient exposure to fine particulate matter (PM 2.5 ) has been linked with AAD, particularly in urban areas. Yet the associations of key PM 2.5 components with specific AAD subtypes remain insufficiently understood. Methods We used a time‐stratified case‐crossover design (2015–2023) in Hangzhou, China, investigating associations of major PM 2.5 components with AAD and its Stanford subtypes. Conditional logistic regression and weighted quantile sum models were applied to explore associations of single and joint exposure to PM 2.5 components with AAD, respectively. Stratified analyses based on age, sex, lifestyle factors, and existing comorbidities were performed. Results At lag 0 to 1 days, black carbon, organic matter, and sulfate were significantly associated with AAD, especially type A, while positive but nonsignificant associations were observed for type B. An interquartile range increase in black carbon, organic matter, and sulfate was associated with a 42% (odds ratio, 1.42 [95% CI, 1.15–1.75]), 35% (odds ratio, 1.35 [95% CI, 1.10–1.64]), and 36% (odds ratio, 1.36 [95% CI, 1.09–1.69]) increased risk of type A AAD, respectively. The weighted quantile sum model revealed significant joint associations of coexposure to major PM 2.5 components with AAD and its type A, with black carbon contributing >50% to the joint associations. Age, smoking, alcohol consumption, and hypertension modified the PM 2.5 components–AAD associations. Conclusions Precise regulation of ambient PM 2.5 components, particularly black carbon, is necessary to mitigate AAD risk. Tailored clinical management is critical for susceptible populations during high‐pollution periods.