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Associations of outdoor air pollution with hemorrhagic stroke mortality
Takashi Yorifuji1, Ichiro Kawachi, Tetsuro Sakamoto
1Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8558, Japan. yorichan@md.okayama-u.ac.jp
Objective:
Evidence linking short-term exposure to outdoor air pollution with hemorrhagic stroke is inconsistent.
Methods:
We evaluated the associations between outdoor air pollution and specific types of stroke in Tokyo, Japan, from April 2003 to December 2008. We obtained daily counts of stroke mortality (n = 41,440) and concentrations of nitrogen dioxide as well as particles less than 2.5 μm in diameter. Time-series analysis was employed.
Results:
Although same-day air pollutants were positively associated with ischemic stroke and intracerebral hemorrhage mortality, both air pollutants were more strongly associated with subarachnoid hemorrhage mortality: rate ratio was 1.041 (95% confidence interval: 1.011-1.072) for each 10 μg/m3 increase in the previous-day particles less than 2.5 μm.
Conclusions:
This study suggests that short-term exposure to outdoor air pollution increases the risks of hemorrhagic stroke mortality as well as ischemic stroke mortality.
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