title: Assessment of personal exposure to ozone in asthmatic children residing in Mexico City.
abstract: OBJECTIVE
  A study was conducted to evaluate personal ozone exposure (O3p) among asthmatic children residing in Mexico City.
  
  
  METHODS
  A total of 158 children were recruited from December 1998 to April 2000. On average, three O3p measurements were obtained per child using passive badges. Time-activity patterns were recorded in a diary. Daily ambient ozone measurements (O3a) were obtained from the fixed station, according to children's residence. Levels of O3a and ozone, weighted by time spent in different micro-environments (O3w), were used as independent variables in order to model O3p concentrations using a mixed-effects model.
  
  
  RESULTS
  Mean O3p was 7.8 ppb. The main variables in the model were: time spent indoors, distance between residence and fixed station, follow-up group, and two interaction terms (overall R(2)=0.50, p<0.05).
  
  
  CONCLUSIONS
  The O3w concentrations can be used as a proxy for O3p, taking into account time-activity patterns and the place of residence of asthmatic Mexican children.
authors.affiliation: Instituto Nacional de Salud Pública, Universidad 655, Cuernavaca, Mexico.
authors.forename: Matiana
authors.initials: M
authors.lastname: Ramírez-Aguilar
authors.forename: Albino
authors.initials: A
authors.lastname: Barraza-Villarreal
authors.forename: Hortensia
authors.initials: H
authors.lastname: Moreno-Macías
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Winer
authors.forename: Pablo
authors.initials: P
authors.lastname: Cicero-Fernández
authors.forename: Ma Guadalupe Doris
authors.initials: MG
authors.lastname: Vélez-Márquez
authors.forename: Marlene
authors.initials: M
authors.lastname: Cortez-Lugo
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Sienra-Monge
authors.forename: Isabelle
authors.initials: I
authors.lastname: Romieu
mesh_terms: D000293:Adolescent; D001249:Asthma; D002648:Child; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D008297:Male; D008800:Mexico; D010126:Ozone / Q000009:adverse effects*; D014505:Urban Population
chemical_list: D010126:Ozone