title: Fine particulate matter air pollution, proximity to traffic, and aortic atherosclerosis.
abstract: BACKGROUND
  The initiation and acceleration of atherosclerosis is hypothesized as a physiologic mechanism underlying associations between air pollution and cardiovascular effects. Despite toxicologic evidence, epidemiologic data are limited.
  
  
  METHODS
  In this cross-sectional analysis we investigated exposure to fine particulate matter (PM2.5) and residential proximity to major roads in relation to abdominal aortic calcification, a sensitive indicator of systemic atherosclerosis. Aortic calcification was measured by computed tomography among 1147 persons, in 5 US metropolitan areas, enrolled in the Multi-Ethnic Study of Atherosclerosis. The presence and quantity of aortic calcification were modeled using relative risk regression and linear regression, respectively, with adjustment for potential confounders.
  
  
  RESULTS
  We observed a slightly elevated risk of aortic calcification (RR = 1.06; 95% confidence interval = 0.96-1.16) with a 10 microg/m contrast in PM2.5. The PM2.5-associated risk of aortic calcification was stronger among participants with long-term residence near a PM2.5 monitor (RR = 1.11; 1.00-1.24) and among participants not recently employed outside the home (RR = 1.10; 1.00-1.22). PM2.5 was not associated with an increase in the quantity of aortic calcification (Agatston score) and no roadway proximity effects were noted. There was indication of PM2.5 effect modification by lipid-lowering medication use, with greater effects among users, and PM2.5 associations were observed most consistently among Hispanics.
  
  
  CONCLUSIONS
  Although we did not find persuasive associations across our full study population, associations were stronger among participants with less exposure misclassification. These findings support the hypothesis of a relationship between particulate air pollution and systemic atherosclerosis.
authors.affiliation: Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada. allenr@sfu.ca
authors.forename: Ryan W
authors.initials: RW
authors.lastname: Allen
authors.forename: Michael H
authors.initials: MH
authors.lastname: Criqui
authors.forename: Ana V
authors.initials: AV
authors.lastname: Diez Roux
authors.forename: Matthew
authors.initials: M
authors.lastname: Allison
authors.forename: Steven
authors.initials: S
authors.lastname: Shea
authors.forename: Robert
authors.initials: R
authors.lastname: Detrano
authors.forename: Lianne
authors.initials: L
authors.lastname: Sheppard
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Wong
authors.forename: Karen Hinckley
authors.initials: KH
authors.lastname: Stukovsky
authors.forename: Joel D
authors.initials: JD
authors.lastname: Kaufman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000032:analysis*; D001012:Aorta, Abdominal / Q000503:physiopathology*; D050197:Atherosclerosis / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011859:Radiography; D018570:Risk Assessment; D014481:United States / Q000453:epidemiology; D001335:Vehicle Emissions
chemical_list: D000393:Air Pollutants; D001335:Vehicle Emissions