title: A comparison of proximity and land use regression traffic exposure models and wheezing in infants.
abstract: BACKGROUND
  We previously reported an association between infant wheezing and residence < 100 m from stop-and-go bus and truck traffic. The use of a proximity model, however, may lead to exposure misclassification.
  
  
  OBJECTIVE
  Results obtained from a land use regression (LUR) model of exposure to truck and bus traffic are compared with those obtained with a proximity model. The estimates derived from the LUR model were then related to infant wheezing.
  
  
  METHODS
  We derived a marker of diesel combustion--elemental carbon attributable to traffic sources (ECAT)--from ambient monitoring results of particulate matter with aerodynamic diameter < 2.5 microm. We developed a multiple regression model with ECAT as the outcome variable. Variables included in the model were locations of major roads, bus routes, truck traffic count, and elevation. Model parameter estimates were applied to estimate individual ECAT levels at infants' homes.
  
  
  RESULTS
  The levels of estimated ECAT at the monitoring stations ranged from 0.20 to 1.02 microg/m(3). A LUR model of exposure with a coefficient of determination (R(2)) of 0.75 was applied to infants' homes. The mean (+/- SD) ambient exposure of ECAT for infants previously categorized as unexposed, exposed to stop-and-go traffic, or exposed to moving traffic was 0.32 +/- 0.06, 0.42 +/- 0.14, and 0.49 +/- 0.14 microg/m(3), respectively. Levels of ECAT from 0.30 to 0.90 mug/m(3) were significantly associated with infant wheezing.
  
  
  CONCLUSIONS
  The LUR model resulted in a range of ECAT individually derived for all infants' homes that may reduce the exposure misclassification that can arise from a proximity model.
authors: Department of Environmental Health, University of Cincinnati Medical Center, Cincinnati, Ohio 45267, USA. patrick.ryan@uc.edu
authors: Patrick H
authors: PH
authors: Ryan
authors: Grace K
authors: GK
authors: Lemasters
authors: Pratim
authors: P
authors: Biswas
authors: Linda
authors: L
authors: Levin
authors: Shaohua
authors: S
authors: Hu
authors: Mark
authors: M
authors: Lindsey
authors: David I
authors: DI
authors: Bernstein
authors: James
authors: J
authors: Lockey
authors: Manuel
authors: M
authors: Villareal
authors: Gurjit K
authors: GK
authors: Khurana Hershey
authors: Sergey A
authors: SA
authors: Grinshpun
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002244:Carbon / Q000032:analysis / Q000737:chemistry; D015331:Cohort Studies; D004781:Environmental Exposure; D004784:Environmental Monitoring; D006798:Housing; D006801:Humans; D007223:Infant; D008954:Models, Biological; D008956:Models, Chemical; D010316:Particle Size; D012044:Regression Analysis; D012135:Respiratory Sounds / Q000209:etiology*; D012307:Risk Factors; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D001335:Vehicle Emissions; D002244:Carbon