title: Residential traffic-related pollution exposures and exhaled nitric oxide in the children's health study.
abstract: BACKGROUND
  The fractional concentration of nitric oxide in exhaled air (FeNO) potentially detects airway inflammation related to air pollution exposure. Existing studies have not yet provided conclusive evidence on the association of FeNO with traffic-related pollution (TRP).
  
  
  OBJECTIVE
  We evaluated the association of FeNO with residential TRP exposure in a large cohort of children.
  
  
  METHODS
  We related FeNO measured on 2,143 children (ages 7-11 years) who participated in the Southern California Children's Health Study (CHS) to five classes of metrics of residential TRP: distances to freeways and major roads; length of all and local roads within circular buffers around the home; traffic densities within buffers; annual average line source dispersion modeled nitrogen oxides (NOx) from freeways and nonfreeway roads; and predicted annual average nitrogen oxide, nitrogen dioxide, and NOx from a model based on intracommunity sampling in the CHS.
  
  
  RESULTS
  In children with asthma, length of roads was positively associated with FeNO, with stronger associations in smaller buffers [46.7%; 95% confidence interval (CI), 14.3-88.4], 12.4% (95% CI, -8.8 to 38.4), and 4.1% (95% CI, -14.6 to 26.8) higher FeNO for 100-, 300-, and 1,000-m increases in the length of all roads in 50-, 100-, and 200-m buffers, respectively. Other TRP metrics were not significantly associated with FeNO, even though the study design was powered to detect exposures explaining as little as 0.4% of the variation in natural log-transformed FeNO (R2 = 0.004).
  
  
  CONCLUSIONS
  Length of road was the only indicator of residential TRP exposure associated with airway inflammation in children with asthma, as measured by FeNO.
authors.affiliation: University of Southern California, Los Angeles, California, USA. eckel@usc.edu
authors.forename: Sandrah P
authors.initials: SP
authors.lastname: Eckel
authors.forename: Kiros
authors.initials: K
authors.lastname: Berhane
authors.forename: Muhammad T
authors.initials: MT
authors.lastname: Salam
authors.forename: Edward B
authors.initials: EB
authors.lastname: Rappaport
authors.forename: William S
authors.initials: WS
authors.lastname: Linn
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Bastain
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.forename: Frederick
authors.initials: F
authors.lastname: Lurmann
authors.forename: Edward L
authors.initials: EL
authors.lastname: Avol
authors.forename: Frank D
authors.initials: FD
authors.lastname: Gilliland
mesh_terms: D000397:Air Pollution; D001249:Asthma / Q000453:epidemiology / Q000209:etiology; D002648:Child; D004781:Environmental Exposure / Q000009:adverse effects; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis* / Q000378:metabolism; D009585:Nitrogen Dioxide / Q000032:analysis / Q000378:metabolism; D001335:Vehicle Emissions / Q000633:toxicity
chemical_list: D001335:Vehicle Emissions; D009569:Nitric Oxide; D009585:Nitrogen Dioxide