title: Validity of a traffic air pollutant dispersion model to assess exposure to fine particles.
abstract: BACKGROUND
  Fine particles (PM(2.5)) are an important component of air pollution. Epidemiological studies have shown health effects due to ambient air particles, particularly allergies in children. Since the main difficulty is to determine exposure to such pollution, traffic air pollutant (TAP) dispersions models have been developed to improve the estimation of individual exposure levels. One such model, the ExTra index, has been validated for nitrogen oxide concentrations but not for other pollutants. The purpose of this study was to assess the validity of the ExTra index to assess PM(2.5) exposure.
  
  
  METHODS
  We compared PM(2.5) concentrations calculated by the ExTra index to reference measures (passive samplers situated under the covered part of the playground), in 15 schools in Bordeaux, in 2000. First, we collected the input data required by the ExTra index: background and local pollution depending on traffic, meteorology and topography. Second, the ExTra index was calculated for each school. Statistical analysis consisted of a graphic description; then, we calculated an intraclass correlation coefficient.
  
  
  RESULTS
  Concentrations calculated with the ExTra index and the reference method were similar. The ExTra index underestimated exposure by 2.2 microg m(-3) on average compared to the reference method. The intraclass correlation coefficient was 0.85 and its 95% confidence interval was [0.62; 0.95].
  
  
  CONCLUSIONS
  The results suggest that the ExTra index provides an assessment of PM(2.5) exposure similar to that of the reference method. Although caution is required in interpreting these results owing to the small number of sites, the ExTra index could be a useful epidemiological tool for reconstructing individual exposure, an important challenge in epidemiology.
authors: Laboratoire Santé Travail Environnement (LSTE), EA 3672, ISPED-Université Victor Segalen Bordeaux 2, Case 11, 146 Rue Léo Saignat, 33076 Bordeaux Cedex, France. Aude.Kostrzewa@isped.u-bordeaux2.fr
authors: Aude
authors: A
authors: Kostrzewa
authors: Patrice
authors: P
authors: Reungoat
authors: Chantal
authors: C
authors: Raherison
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002648:Child; D003627:Data Interpretation, Statistical; D004784:Environmental Monitoring / Q000379:methods* / Q000706:statistics & numerical data; D005602:France; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis*; D008962:Models, Theoretical; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D015203:Reproducibility of Results; D012107:Research Design; D012574:Schools / Q000592:standards
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter