title: Particulate air pollution and vascular reactivity: the bus stop study.
abstract: OBJECTIVE
  Particulate air pollution is associated with cardiovascular morbidity but mechanisms are not well understood. We tested the effects on vascular reactivity of exposure to fine particulates matter mass (PM(2.5)), number of particles <or=1 microm/m(3) (PM(1.0)) and nitrogen dioxide concentration (NO(2)).
  
  
  METHODS
  About 39 healthy volunteers sat outside for 2 h at two different Ottawa bus stops. Flow-mediated vasodilation (FMD) of the brachial artery was then measured by ultrasound and expressed as: (maximum artery diameter after release of a blood pressure cuff inflated above systolic pressure-baseline resting diameter)/baseline resting diameter.
  
  
  RESULTS
  A 30 microg/m(3) increase in PM(2.5) exposure corresponded to a 0.48% reduction in FMD, P=0.05 representing a 5% relative change in the maximum ability to dilate. Results were consistent between the two bus stops and not sensitive to type of analysis. No significant association was found between FMD and NO(2), PM(1.0) or traffic density.
  
  
  CONCLUSIONS
  PM(2.5) may reduce the capacity to vasodilate, a potential explanation for the documented association with cardiovascular morbidity.
authors.affiliation: Health Canada, A.L. 4602C, 400 Cooper Street, Room 2045, Ottawa, ON, Canada K1A 0K9. rdales@ohri.ca
authors.forename: Robert
authors.initials: R
authors.lastname: Dales
authors.forename: Ling
authors.initials: L
authors.lastname: Liu
authors.forename: Mietek
authors.initials: M
authors.lastname: Szyszkowicz
authors.forename: Mary
authors.initials: M
authors.lastname: Dalipaj
authors.forename: Jeff
authors.initials: J
authors.lastname: Willey
authors.forename: Ryan
authors.initials: R
authors.lastname: Kulka
authors.forename: Terrence D
authors.initials: TD
authors.lastname: Ruddy
mesh_terms: D000293:Adolescent; D000328:Adult; D001808:Blood Vessels / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018986:Motor Vehicles; D009864:Ontario; D052638:Particulate Matter / Q000009:adverse effects / Q000032:analysis*; D014505:Urban Population
chemical_list: D052638:Particulate Matter