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Associations of Particulate Matter With Stroke Mortality: A Multicity Study in Japan

Yorifuji, Takashi MD; Kashima, Saori PhD

Journal of Occupational and Environmental Medicine: July 2013 - Volume 55 - Issue 7 - p 768–771
doi: 10.1097/JOM.0b013e3182973092
Original Articles

Objective: Evidence linking short-term exposure to outdoor air pollution with hemorrhagic stroke is inconclusive.

Methods: We evaluated the effects of suspended particulate matter (SPM) on cardiovascular disease mortality, focusing on types of stroke, from March 2005 to December 2010, in five selected prefectures in western Japan. A multicity time-series analysis was used, and Asian dust was adjusted in the models.

Results: Even after adjusting for Asian dust, the same-day SPM was positively associated with several types of stroke mortality. Following a 10-μg/m3 increase in SPM, rate ratios were 1.014 (90% confidence interval [CI]: 1.002 to 1.026) for stroke, 1.030 (90% CI: 1.004 to 1.056) for intracerebral hemorrhage, and 1.016 (90% CI: 1.003 to 1.030) for ischemic stroke mortality.

Conclusions: Short-term exposure to outdoor air pollution may increase the risks of hemorrhagic stroke as well as ischemic stroke mortality.

From the Department of Human Ecology (Dr Yorifuji), Okayama University Graduate School of Environmental and Life Science, Kita-ku, Okayama, Japan; and Department of Public Health and Health Policy (Dr Kashima), Institute of Biomedical and Health Sciences, Hiroshima University, Minami-ku, Hiroshima, Japan.

Address correspondence to: Takashi Yorifuji, MD, Department of Human Ecology, Okayama University Graduate School of Environmental and Life Science, 3-1-1 Tsushima-naka, Kita-ku, Okayama, 700-8530, Japan (

This study was supported by Grant-in-Aid for Young Scientists (B) No 23790663 and Grant-in-Aid for Scientific Research (C) No 24510033 from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

Authors Yorifuji and Kashima have no relationships/conditions/circumstances that present potential conflict of interest.

The JOEM editorial board and planners have no financial interest related to this research.

Copyright © 2013 by the American College of Occupational and Environmental Medicine