title: Synergistic effects of exposure to concentrated ambient fine pollution particles and nitrogen dioxide in humans.
abstract: BACKGROUND
  Exposure to single pollutants e.g. particulate matter (PM) is associated with adverse health effects, but it does not represent a real world scenario that usually involves multiple pollutants.
  
  
  OBJECTIVE
  Determine if simultaneous exposure to PM and NO₂ results in synergistic interactions.
  
  
  METHODS
  Healthy young volunteers were exposed to clean air, nitrogen dioxide (NO₂, 0.5 ppm), concentrated fine particles from Chapel Hill air (PM(2.5)CAPs, 89.5 ± 10.7 µg/m³), or NO₂+PM(2.5)CAPs for 2 h. Each subject performed intermittent exercise during the exposure. Parameters of heart rate variability (HRV), changes in repolarization, peripheral blood endpoints and lung function were measured before and 1 and 18 h after exposure. Bronchoalveolar lavage (BAL) was performed 18 h after exposure.
  
  
  RESULTS
  NO₂ exposure alone increased cholesterol and HDL 18 h after exposure, decreased high frequency component of HRV one and 18 h after exposure, decreased QT variability index 1 h after exposure, and increased LDH in BAL fluid. The only significant change with PM(2.5)CAPs was an increase in HDL 1 h after exposure, likely due to the low concentrations of PM(2.5)CAPs in the exposure chamber. Exposure to both NO₂ and PM(2.5)CAPs increased BAL α1-antitrypsin, mean t wave amplitude, the low frequency components of HRV and the LF/HF ratio. These changes were not observed following exposure to NO₂ or PM(2.5)CAPs alone, suggesting possible interactions between the two pollutants.
  
  
  CONCLUSIONS
  NO₂ exposure may produce and enhance acute cardiovascular effects of PM(2.5)CAPs. Assessment of health effects by ambient PM should consider its interactions with gaseous copollutants.
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA. huang002@mc.duke.edu
authors.forename: Yuh-Chin T
authors.initials: YC
authors.lastname: Huang
authors.forename: Ana G
authors.initials: AG
authors.lastname: Rappold
authors.forename: Donald W
authors.initials: DW
authors.lastname: Graff
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Ghio
authors.forename: Robert B
authors.initials: RB
authors.lastname: Devlin
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000633:toxicity*; D001145:Arrhythmias, Cardiac / Q000139:chemically induced; D001273:Atmosphere Exposure Chambers; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D002317:Cardiovascular Agents / Q000633:toxicity*; D002319:Cardiovascular System / Q000187:drug effects* / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D004357:Drug Synergism; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006937:Hypercholesterolemia / Q000139:chemically induced; D045022:Lactate Dehydrogenases / Q000378:metabolism; D008297:Male; D009585:Nitrogen Dioxide / Q000633:toxicity*; D009657:North Carolina; D052638:Particulate Matter / Q000633:toxicity*; D055815:Young Adult; D000515:alpha 1-Antitrypsin / Q000378:metabolism
chemical_list: D000393:Air Pollutants; D002317:Cardiovascular Agents; D052638:Particulate Matter; C043392:SERPINA1 protein, human; D000515:alpha 1-Antitrypsin; D002784:Cholesterol; D045022:Lactate Dehydrogenases; D009585:Nitrogen Dioxide