title: Short-term effects of fine particulate air pollution on cardiovascular hospital emergency room visits: a time-series study in Beijing, China.
abstract: BACKGROUND
  The link between particulate matter (PM) and cardiovascular morbidity has been investigated in numerous studies. Less evidence exists, however, about how age, gender and season may modify this relationship. The aim of this study was to evaluate the association between ambient PM2.5 (PM ≤ 2.5 µm) and daily hospital emergency room visits (ERV) for cardiovascular diseases in Beijing, China. Moreover, potential effect modification by age, gender, season, air mass origin and the specific period with 2008 Beijing Olympic were investigated. Finally, the temporal lag structure of PM2.5 has also been explored.
  
  
  METHODS
  Daily counts of cardiovascular ERV were obtained from the Peking University Third Hospital from January 2007 to December 2008. Concurrently, data on PM2.5, PM10 (PM ≤ 10 µm), nitrogen dioxide and sulfur dioxide concentrations were obtained from monitoring networks and a fixed monitoring station. Poisson regression models adjusting for confounders were used to estimate immediate, delayed and cumulative air pollution effects. The temporal lag structure was also estimated using polynomial distributed lag (PDL) models. We calculated the relative risk (RR) for overall cardiovascular disease ERV as well as for specific causes of disease; and also investigated the potential modifying effect of age, gender, season, air mass origin and the period with 2008 Beijing Olympics.
  
  
  RESULTS
  We observed adverse effects of PM2.5 on cardiovascular ERV--an IQR increase (68 μg/m(3)) in PM2.5 was associated with an overall RR of 1.022 (95% CI 0.990-1.057) obtained from PDL model. Strongest effects of PM2.5 on cardiovascular ERV were found for a lag of 7 days; the respective estimate was 1.012 (95% CI 1.002-1.022). The effects were more pronounced in females and in spring. Arrhythmia and cerebrovascular diseases showed a stronger association with PM2.5. We also found stronger PM-effects for stagnant and southern air masses and the period of Olympics modified the air pollution effects.
  
  
  CONCLUSIONS
  We observed a rather delayed effect of PM2.5 on cardiovascular ERV, which was modified by gender and season. Our findings provide new evidence about effect modifications and may have implications to improve policy making for particulate air pollution standards in Beijing, China.
authors.affiliation: Institute of Epidemiology II, Helmholtz Zentrum München - German Research Center for Environmental Health, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany. suchang1986@gmail.com.|School of Public Health, Peking University Health Science Center, Beijing, China. suchang1986@gmail.com.
authors.forename: Chang
authors.initials: C
authors.lastname: Su
authors.affiliation: Institute of Epidemiology II, Helmholtz Zentrum München - German Research Center for Environmental Health, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Breitner
authors.affiliation: Institute of Epidemiology II, Helmholtz Zentrum München - German Research Center for Environmental Health, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Schneider
authors.affiliation: School of Public Health, Peking University Health Science Center, Beijing, China.
authors.forename: Liqun
authors.initials: L
authors.lastname: Liu
authors.affiliation: Core Facility Studies, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Franck
authors.affiliation: Institute of Epidemiology II, Helmholtz Zentrum München - German Research Center for Environmental Health, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Peters
authors.affiliation: School of Public Health, Peking University Health Science Center, Beijing, China.
authors.forename: Xiaochuan
authors.initials: X
authors.lastname: Pan
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000392:Air Movements; D000397:Air Pollution / Q000009:adverse effects / Q000706:statistics & numerical data*; D000068476:Beijing; D002318:Cardiovascular Diseases / Q000209:etiology / Q000628:therapy*; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D004781:Environmental Exposure / Q000009:adverse effects / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009585:Nitrogen Dioxide / Q000633:toxicity; D010316:Particle Size; D052638:Particulate Matter / Q000633:toxicity*; D012621:Seasons; D012737:Sex Factors; D013458:Sulfur Dioxide / Q000633:toxicity; D013997:Time Factors
chemical_list: D052638:Particulate Matter; D013458:Sulfur Dioxide; D009585:Nitrogen Dioxide
keywords: Cardiovascular diseases; Emergency room visits; Fine particulate matter; Polynomial distributed model; Time-series study