title: Short-term exposure to air pollution and incidence of stroke and acute myocardial infarction in a Japanese population.
abstract: BACKGROUND
  Exposure to high levels of air pollution can increase the risk of cardiovascular events. However, there is no clear information in Japan on the effect of pollution on the incidence of stroke and acute myocardial infarction (AMI). Therefore, we investigated the effects of air pollution on the incidence of stroke and AMI in a setting where pollutant levels are rather low.
  
  
  METHODS
  Data were obtained from the Takashima Stroke and AMI Registry, which covers a population of approximately 55,000 in Takashima County in central Japan. We applied a time-stratified, bidirectional, case-crossover design to estimate the effects of air pollutants, which included suspended particulate matter (SPM), sulfur dioxide (SO(2)), nitrogen dioxide (NO(2)) and photochemical oxidants (Ox). We used the distributed lag model to estimate the effect of pollutant exposure 0-3 days before the day of event onset and controlled for meteorological covariates in all of the models.
  
  
  RESULTS
  There were 2,038 first-ever strokes (1,083 men, 955 women) and 429 first-ever AMI cases (281 men, 148 women) during 1988-2004. The mean pollutant levels were as follows: SPM 26.9 μg/m(3); SO(2) 3.9 ppb; NO(2) 16.0 ppb, and Ox 28.4 ppb. In single-pollutant and two-pollutant models, SO(2) was associated with the risk of cerebral hemorrhage. Other stroke subtypes and AMI were not associated with air pollutant levels.
  
  
  CONCLUSIONS
  We observed an association between SO(2) and hemorrhagic stroke; however, we found inconclusive evidence for a short-term effect of air pollution on the incidence of other stroke types and AMI.
authors.affiliation: Department of Health Science, Shiga University of Medical Science, Shiga, Japan. turin.chowdhury@ucalgary.ca
authors.forename: Tanvir Chowdhury
authors.initials: TC
authors.lastname: Turin
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Kita
authors.forename: Nahid
authors.initials: N
authors.lastname: Rumana
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Kayo
authors.initials: K
authors.lastname: Ueda
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Takashima
authors.forename: Hideki
authors.initials: H
authors.lastname: Sugihara
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Morita
authors.forename: Masaharu
authors.initials: M
authors.lastname: Ichikawa
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Hirose
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nitta
authors.forename: Akira
authors.initials: A
authors.lastname: Okayama
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Miura
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Ueshima
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000397:Air Pollution / Q000706:statistics & numerical data*; D002543:Cerebral Hemorrhage / Q000453:epidemiology; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology*; D009585:Nitrogen Dioxide; D010083:Oxidants, Photochemical; D052638:Particulate Matter; D020521:Stroke / Q000453:epidemiology*; D013458:Sulfur Dioxide
chemical_list: D010083:Oxidants, Photochemical; D052638:Particulate Matter; D013458:Sulfur Dioxide; D009585:Nitrogen Dioxide