title: The exposure-dependent effects of aged secondhand smoke on endothelial function.
abstract: OBJECTIVE
  The aim of this study was to investigate whether exposure to a range of relatively low concentrations of aged secondhand smoke (SHS), similar to those encountered commonly in the community, would impair endothelial function in a concentration-dependent manner.
  
  
  BACKGROUND
  Exposure to SHS impairs endothelial function in humans. The concentration-dependent relationship for aged SHS effects on endothelial function after an exposure of short duration is unknown.
  
  
  METHODS
  Thirty-three healthy nonsmokers were exposed to 1 of 2 low levels of aged SHS or to conditioned filtered air for 30 min. The primary end point was change in maximal percent brachial artery flow-mediated dilation after exposure.
  
  
  RESULTS
  In a linear regression model for each increase in SHS exposure by 100 μg/m(3) respirable suspended particles, the absolute maximal percent brachial artery flow-mediated dilation was reduced by 0.67%. We did not find evidence of a threshold for the effect of SHS on flow-mediated dilation.
  
  
  CONCLUSIONS
  Short-term exposure to real-world levels of aged SHS for 30 min resulted in a concentration-dependent decrease in endothelial function as measured by flow-mediated dilation.
authors.affiliation: Division of Cardiology, San Francisco General Hospital, San Francisco, CA 94110, USA.
authors.forename: Paul F
authors.initials: PF
authors.lastname: Frey
authors.forename: Peter
authors.initials: P
authors.lastname: Ganz
authors.forename: Priscilla Y
authors.initials: PY
authors.lastname: Hsue
authors.forename: Neal L
authors.initials: NL
authors.lastname: Benowitz
authors.forename: Stanton A
authors.initials: SA
authors.lastname: Glantz
authors.forename: John R
authors.initials: JR
authors.lastname: Balmes
authors.forename: Suzaynn F
authors.initials: SF
authors.lastname: Schick
mesh_terms: D000328:Adult; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000503:physiopathology*; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D014028:Tobacco Smoke Pollution