title: Vascular responses to long- and short-term exposure to fine particulate matter: MESA Air (Multi-Ethnic Study of Atherosclerosis and Air Pollution).
abstract: OBJECTIVE
  This study evaluated the association of long- and short-term air pollutant exposures with flow-mediated dilation (FMD) and baseline arterial diameter (BAD) of the brachial artery using ultrasound in a large multicity cohort.
  
  
  BACKGROUND
  Exposures to ambient air pollution, especially long-term exposure to particulate matter <2.5 μm in aerodynamic diameter (PM(2.5)), are linked with cardiovascular mortality. Short-term exposure to PM(2.5) has been associated with decreased FMD and vasoconstriction, suggesting that adverse effects of PM(2.5) may involve endothelial dysfunction. However, long-term effects of PM(2.5) on endothelial dysfunction have not been investigated.
  
  
  METHODS
  FMD and BAD were measured by brachial artery ultrasound at the initial examination of the Multi-Ethnic Study of Atherosclerosis. Long-term PM(2.5) concentrations were estimated for the year 2000 at each participant's residence (n = 3,040) using a spatio-temporal model informed by cohort-specific monitoring. Short-term PM(2.5) concentrations were based on daily central-site monitoring in each of the 6 cities.
  
  
  RESULTS
  An interquartile increase in long-term PM(2.5) concentration (3 μg/m(3)) was associated with a 0.3% decrease in FMD (95% confidence interval [CI] of difference: -0.6 to -0.03; p = 0.03), adjusting for demographic characteristics, traditional risk factors, sonographers, and 1/BAD. Women, nonsmokers, younger participants, and those with hypertension seemed to show a greater association of PM(2.5) with FMD. FMD was not significantly associated with short-term variation in PM(2.5) (-0.1% per 12 μg/m(3) daily increase [95% CI: -0.2 to 0.04] on the day before examination).
  
  
  CONCLUSIONS
  Long-term PM(2.5) exposure was significantly associated with decreased endothelial function according to brachial ultrasound results. These findings may elucidate an important pathway linking air pollution and cardiovascular mortality.
authors.affiliation: Department of Medicine, University of Washington, 4225 Roosevelt Way NE, Seattle, WA 98105, USA. ranjik@u.washington.edu
authors.forename: Ranjini M
authors.initials: RM
authors.lastname: Krishnan
authors.forename: Sara D
authors.initials: SD
authors.lastname: Adar
authors.forename: Adam A
authors.initials: AA
authors.lastname: Szpiro
authors.forename: Neal W
authors.initials: NW
authors.lastname: Jorgensen
authors.forename: Victor C
authors.initials: VC
authors.lastname: Van Hee
authors.forename: R Graham
authors.initials: RG
authors.lastname: Barr
authors.forename: Marie S
authors.initials: MS
authors.lastname: O'Neill
authors.forename: David M
authors.initials: DM
authors.lastname: Herrington
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Polak
authors.forename: Joel D
authors.initials: JD
authors.lastname: Kaufman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects*; D050197:Atherosclerosis / Q000139:chemically induced / Q000208:ethnology*; D016001:Confidence Intervals; D005006:Ethnicity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter / Q000009:adverse effects*; D011446:Prospective Studies; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D014481:United States / Q000453:epidemiology
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter