title: Effects of particulate air pollution on blood pressure in a highly exposed population in Beijing, China: a repeated-measure study.
abstract: BACKGROUND
  Particulate Matter (PM) exposure is critical in Beijing due to high population density and rapid increase in vehicular traffic. PM effects on blood pressure (BP) have been investigated as a mechanism mediating cardiovascular risks, but results are still inconsistent. The purpose of our study is to determine the effects of ambient and personal PM exposure on BP.
  
  
  METHODS
  Before the 2008 Olympic Games (June 15-July 27), we examined 60 truck drivers and 60 office workers on two days, 1-2 weeks apart (n = 240). We obtained standardized measures of post-work BP. Exposure assessment included personal PM(2.5) and Elemental Carbon (EC, a tracer of traffic particles) measured using portable monitors during work hours; and ambient PM(10) averaged over 1-8 days pre-examination. We examined associations of exposures (exposure group, personal PM(2.5)/EC, ambient PM(10)) with BP controlling for multiple covariates.
  
  
  RESULTS
  Mean personal PM(2.5) was 94.6 μg/m(3) (SD = 64.9) in office workers and 126.8 (SD = 68.8) in truck drivers (p-value < 0.001). In all participants combined, a 10 μg/m(3) increase in 8-day ambient PM(10) was associated with BP increments of 0.98 (95%CI 0.34; 1.61; p-value = 0.003), 0.71 (95%CI 0.18; 1.24; p-value = 0.01), and 0.81 (95%CI 0.31; 1.30; p-value = 0.002) mmHg for systolic, diastolic, and mean BP, respectively. BP was not significantly different between the two groups (p-value > 0.14). Personal PM(2.5) and EC during work hours were not associated with increased BP.
  
  
  CONCLUSIONS
  Our results indicate delayed effects of ambient PM(10) on BP. Lack of associations with exposure groups and personal PM(2.5)/EC indicates that PM effects are related to background levels of pollution in Beijing, and not specifically to work-related exposure.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Baccarelli
authors.forename: Francesco
authors.initials: F
authors.lastname: Barretta
authors.forename: Chang
authors.initials: C
authors.lastname: Dou
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhang
authors.forename: John P
authors.initials: JP
authors.lastname: McCracken
authors.forename: Anaité
authors.initials: A
authors.lastname: Díaz
authors.forename: Pier Alberto
authors.initials: PA
authors.lastname: Bertazzi
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.forename: Sheng
authors.initials: S
authors.lastname: Wang
authors.forename: Lifang
authors.initials: L
authors.lastname: Hou
mesh_terms: D000328:Adult; D001794:Blood Pressure; D002318:Cardiovascular Diseases / Q000139:chemically induced*; D002681:China; D002947:Cities; D004781:Environmental Exposure; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D052638:Particulate Matter / Q000032:analysis / Q000633:toxicity*; D013997:Time Factors; D055815:Young Adult
chemical_list: D052638:Particulate Matter