title: Residential traffic and children's respiratory health.
abstract: BACKGROUND
  Living near traffic has been associated with asthma and other respiratory symptoms. Most studies, however, have been conducted in areas with high background levels of ambient air pollution, making it challenging to isolate an independent effect of traffic. Additionally, most investigations have used surrogates of exposure, and few have measured traffic pollutants directly as part of the study.
  
  
  OBJECTIVE
  We conducted a cross-sectional study of current asthma and other respiratory symptoms in children (n = 1,080) living at varying distances from high-traffic roads in the San Francisco Bay Area, California, a highly urbanized region characterized by good regional air quality due to coastal breezes.
  
  
  METHODS
  We obtained health information and home environmental factors by parental questionnaire. We assessed exposure with several measures of residential proximity to traffic calculated using geographic information systems, including traffic within a given radius and distance to major roads. We also measured traffic-related pollutants (nitrogen oxides and nitrogen dioxide) for a subset of households to determine how well traffic metrics correlated with measured traffic pollutants.
  
  
  RESULTS
  Using multivariate logistic regression analyses, we found associations between current asthma and residential proximity to traffic. For several traffic metrics, children whose residences were in the highest quintile of exposure had approximately twice the adjusted odds of current asthma (i.e., asthma episode in the preceeding 12 months) compared with children whose residences were within the lowest quintile. The highest risks were among those living within 75 m of a freeway/highway. Most traffic metrics correlated moderately well with actual pollutant measurements.
  
  
  CONCLUSIONS
  Our findings provide evidence that even in an area with good regional air quality, proximity to traffic is associated with adverse respiratory health effects in children.
authors.affiliation: Office of Environmental Health Hazard Assessment, Air Pollution Epidemiology Section, Oakland, California, USA.
authors.forename: Janice J
authors.initials: JJ
authors.lastname: Kim
authors.forename: Karen
authors.initials: K
authors.lastname: Huen
authors.forename: Sara
authors.initials: S
authors.lastname: Adams
authors.forename: Svetlana
authors.initials: S
authors.lastname: Smorodinsky
authors.forename: Abby
authors.initials: A
authors.lastname: Hoats
authors.forename: Brian
authors.initials: B
authors.lastname: Malig
authors.forename: Michael
authors.initials: M
authors.lastname: Lipsett
authors.forename: Bart
authors.initials: B
authors.lastname: Ostro
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D002648:Child; D003430:Cross-Sectional Studies; D006801:Humans; D015999:Multivariate Analysis; D012129:Respiratory Function Tests; D001335:Vehicle Emissions
chemical_list: D000393:Air Pollutants; D001335:Vehicle Emissions
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