  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.
