title: Acute changes in vascular function among welders exposed to metal-rich particulate matter.
abstract: BACKGROUND
  Although welding fume exposure is associated with adverse cardiovascular outcomes, the mechanisms remain unclear. To investigate the role of vascular function, we assessed levels of the augmentation index (a correlate of arterial stiffness) after short-term exposure to welding-derived fine particulate matter (PM2.5).
  
  
  METHODS
  In a panel study, we monitored 26 male welders over 24 hours on a welding day (n = 25), a non-welding day (n = 15), or both (n = 14). Augmentation index (expressed as a percent) was obtained in the morning before exposure (baseline) and after exposure in the afternoon and the following morning. Personal PM2.5 exposure was measured over 6 hours of welding or an equivalent non-welding period. We used linear mixed models adjusting for baseline augmentation index, smoking, age, and time to evaluate the effects of welding (binary) and PM2.5 (continuous) on augmentation index levels. We also assessed modification by welding exposure the day before monitoring (binary).
  
  
  RESULTS
  Welding was associated with a 2.8% increase in afternoon augmentation index (95% confidence interval = -1.4 to 7.0) and a 2.4% decrease (-6.9 to 2.2) in next-morning augmentation index. Additional exposure the day prior to monitoring was associated with a greater afternoon increase (5.1%; 0.8 to 9.5). Using PM2.5 concentration, a positive association was observed in the afternoon and an inverse association the next morning; results differed by previous day's welding status after excluding outliers.
  
  
  CONCLUSIONS
  Subsequent to welding fume exposure, there is an increase in afternoon augmentation index and a decrease in next-morning augmentation index, with greater changes after consecutive days of exposure. These results suggest that exposure to the PM2.5 component of welding fume elicits acute adverse vascular responses.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA.
authors.forename: Shona C
authors.initials: SC
authors.lastname: Fang
authors.forename: Ellen A
authors.initials: EA
authors.lastname: Eisen
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Cavallari
authors.forename: Murray A
authors.initials: MA
authors.lastname: Mittleman
authors.forename: David C
authors.initials: DC
authors.lastname: Christiani
mesh_terms: D000328:Adult; D000395:Air Pollutants, Occupational / Q000009:adverse effects*; D001158:Arteries / Q000503:physiopathology*; D001794:Blood Pressure; D001900:Boston / Q000453:epidemiology; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D004784:Environmental Monitoring / Q000379:methods; D062665:Epidemiological Monitoring; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D010316:Particle Size; D052638:Particulate Matter / Q000009:adverse effects*; D012307:Risk Factors; D014661:Vasoconstriction; D014896:Welding
chemical_list: D000395:Air Pollutants, Occupational; D052638:Particulate Matter