Abstract Body: Introduction
We previously reported that acute exposure to fine particulate matter (PM_2.5) within one day before the onset (lag days 0-1) is linked to ischemic stroke events. This study aimed to examine the association between specific components of PM_2.5 and the occurrence of ischemic stroke.
Methods
Toral of 5,872 patients with acute ischemic stroke enrolled in a multicenter, hospital-based stroke registry in Fukuoka, Japan. All patients were previously independent and were hospitalized within 24 hours of stroke onset between November 2013 and September 2019. We collected data on daily mean concentrations of PM_2.5 and its specific chemical components that were measured aerosol speciation analyzers (ACSA, Kimoto Electric Co., Ltd) within Fukuoka city —including optical black carbon, water-soluble organic compounds, nitrate ion, and sulfate ion. The time of symptom onset was confirmed, and the association between these specific PM_2.5 components and ischemic stroke occurrence was analyzed using a time-stratified case-crossover design and a conditional logistic regression model.
Results and Conclusions
Ambient PM_2.5 at lag days 0 to 1 was not associated with the subsequent occurrence of ischemic stroke (percent increase for ischemic stroke per 10 μg/m³ PM_2.5 [95% confidence interval]: 2.7 [-2.7 to 8.3]), after adjusting for ambient temperature, humidity, influenza epidemics, and PM_2.5 at lag days 2 to 3 and lag days 4 to 6. No significant association was found between the specific chemical components of PM_2.5 and ischemic stroke occurrence, either in a single-component model (percent increase for ischemic stroke [95% confidence interval]: optical black carbon, -7.3 [-24.7 to 14.2]; water-soluble organic carbon, -2.6 [-13.6 to 9.8]; nitrate ion, -3.6 [-9.5 to 2.7]; sulfate ion, -0.3 [-3.0 to 2.5]) or in a multicomponent model (percent increase for ischemic stroke [95% confidence interval]: optical black carbon, 0.6 [-23.7 to 32.6]; water-soluble organic carbon, 5.1 [-14.8 to 29.7]; nitrate ion, -6.5 [-16.3 to 4.4]; sulfate ion, 5.1 [-3.1 to 4.0]). These results were consistent across different age groups, sexes, and ischemic stroke etiologies.
In conclusions, these findings suggest that short-term exposure to specific chemical components of PM_2.5 within 1 day before onset is not associated with the subsequent occurrence of ischemic stroke. Further studies are warranted to clarify the effects of PM_2.5 on ischemic stroke occurrence.