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. MATERIAL AND METHODS: A total of 158 chil-dren 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 childrens 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 R²=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.
Main Authors: | , , , , , , , , |
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Format: | Digital revista |
Language: | English |
Published: |
Instituto Nacional de Salud Pública
2008
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Online Access: | http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0036-36342008000100013 |
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Summary: | OBJECTIVE: A study was conducted to evaluate personal ozone exposure (O3p) among asthmatic children residing in Mexico City. MATERIAL AND METHODS: A total of 158 chil-dren 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 childrens 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 R²=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. |
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