Differential impact of acute fine particulate matter exposure on risk of stroke by stroke subtype, age, sex, and race: a case-crossover study

Objective: Association between acute ambient fine particulate matter (PM2.5, aerodynamic diameter less than 2.5 and cardiovascular events are well documented. However, it remains unclear whether acute exposure to PM2.5 acts as a trigger for hemorrhagic (intracerebral or subarachnoid hemorrhage) or non-hemorrhagic (infarct or transient ischemic attack) stroke onset. We, therefore, examined the association between ambient PM2.5 and stroke onset, and whether this relationship differs by stroke subtype, age, sex, and race. Methods: We used a time-stratified case-crossover design to examine the association between exposure to PM2.5 and stroke onset for the calendar year 2010. Data were collected from the Greater Cincinnati Northern Kentucky Stroke Study. We included patients 20 years and older, initially ascertained through hospital ICD-9 discharge codes. Daily ambient concentrations of PM2.5 were estimated from the patient's residential addresses using a spatiotemporal model. Conclusion: Our findings suggest that short-term PM2.5 exposure, particularly at three days before the event, is associated with stroke onset but varies according to stroke subtype, age, sex, and race.