Assessment of personal exposure to ozone in asthmatic children residing in Mexico City.
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.
Ramírez-Aguilar
Matiana
M
Instituto Nacional de Salud Pública, Universidad 655, Cuernavaca, Mexico.
Barraza-Villarreal
Albino
A
Moreno-Macías
Hortensia
H
Winer
Arthur M
AM
Cicero-Fernández
Pablo
P
Vélez-Márquez
Ma Guadalupe Doris
MG
Cortez-Lugo
Marlene
M
Sienra-Monge
Juan José
JJ
Romieu
Isabelle
I
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
D010126:Ozone