title: Fine particulate matter exposure and incidence of stroke: A cohort study in Hong Kong.
abstract: OBJECTIVE
  We aimed to assess the association of long-term residential exposure to fine particulate matter (PM) with aerodynamic diameter less than 2.5 μm (PM2.5) with the incidence of stroke and its major subtypes.
  
  
  METHODS
  We ascertained the first occurrence of emergency hospital admission for stroke in a Hong Kong Chinese cohort of 66,820 older people (65+ years) who enrolled during 1998-2001 (baseline) and were followed up to December 31, 2010. High-resolution (1 × 1 km) yearly mean concentrations of PM2.5were predicted from local monitoring data and US National Aeronautics and Space Administration satellite data using linear regression. Baseline residential PM2.5exposure was used as a proxy for long-term exposure. We used Cox proportional hazards to evaluate the risk of incident stroke associated with PM2.5exposure adjusted for potential confounders, including individual and neighborhood factors.
  
  
  RESULTS
  Over a mean follow-up of 9.4 years, we ascertained 6,733 cases of incident stroke, of which 3,526 (52.4%) were ischemic and 1,175 (17.5%) were hemorrhagic. The hazard ratio for every 10 μg/m3higher PM2.5concentration was statistically significant at 1.21 (95% confidence interval [CI] 1.04-1.41) for ischemic and non-statistically significant at 0.90 (95% CI 0.70-1.17) for hemorrhagic stroke in fully adjusted model 3. The estimates for ischemic stroke were higher in older participants (>70 years), less educated participants, and in men for current smokers.
  
  
  CONCLUSIONS
  Long-term PM2.5exposure was associated with higher risk of incident ischemic stroke, but the association with incident hemorrhagic stroke was less clear.
authors.affiliation: From the School of Public Health (H.Q., S.S., H.T., C.-M.W., C.M.S., L.T.), Li Ka Shing Faculty of Medicine, The University of Hong Kong; and Elderly Health Service, Department of Health (R.S.-y.L.), Hong Kong Special Administrative Region, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Qiu
authors.affiliation: From the School of Public Health (H.Q., S.S., H.T., C.-M.W., C.M.S., L.T.), Li Ka Shing Faculty of Medicine, The University of Hong Kong; and Elderly Health Service, Department of Health (R.S.-y.L.), Hong Kong Special Administrative Region, China.
authors.forename: Shengzhi
authors.initials: S
authors.lastname: Sun
authors.affiliation: From the School of Public Health (H.Q., S.S., H.T., C.-M.W., C.M.S., L.T.), Li Ka Shing Faculty of Medicine, The University of Hong Kong; and Elderly Health Service, Department of Health (R.S.-y.L.), Hong Kong Special Administrative Region, China.
authors.forename: Hilda
authors.initials: H
authors.lastname: Tsang
authors.affiliation: From the School of Public Health (H.Q., S.S., H.T., C.-M.W., C.M.S., L.T.), Li Ka Shing Faculty of Medicine, The University of Hong Kong; and Elderly Health Service, Department of Health (R.S.-y.L.), Hong Kong Special Administrative Region, China.
authors.forename: Chit-Ming
authors.initials: CM
authors.lastname: Wong
authors.affiliation: From the School of Public Health (H.Q., S.S., H.T., C.-M.W., C.M.S., L.T.), Li Ka Shing Faculty of Medicine, The University of Hong Kong; and Elderly Health Service, Department of Health (R.S.-y.L.), Hong Kong Special Administrative Region, China.
authors.forename: Ruby Siu-Yin
authors.initials: RS
authors.lastname: Lee
authors.affiliation: From the School of Public Health (H.Q., S.S., H.T., C.-M.W., C.M.S., L.T.), Li Ka Shing Faculty of Medicine, The University of Hong Kong; and Elderly Health Service, Department of Health (R.S.-y.L.), Hong Kong Special Administrative Region, China.
authors.forename: C Mary
authors.initials: CM
authors.lastname: Schooling
authors.affiliation: From the School of Public Health (H.Q., S.S., H.T., C.-M.W., C.M.S., L.T.), Li Ka Shing Faculty of Medicine, The University of Hong Kong; and Elderly Health Service, Department of Health (R.S.-y.L.), Hong Kong Special Administrative Region, China. linweit@hku.hk.
authors.forename: Linwei
authors.initials: L
authors.lastname: Tian
mesh_terms: D000367:Age Factors; D000368:Aged; D000393:Air Pollutants / Q000009:adverse effects*; D002545:Brain Ischemia / Q000453:epidemiology* / Q000628:therapy; D002543:Cerebral Hemorrhage / Q000453:epidemiology* / Q000628:therapy; D004522:Educational Status; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D052638:Particulate Matter / Q000009:adverse effects*; D010343:Patient Admission; D016016:Proportional Hazards Models; D012306:Risk; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology; D020521:Stroke / Q000453:epidemiology* / Q000628:therapy; D013997:Time Factors
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter