American Journal ol Epidemiology Copyright © 1992 by The Johns Hopkins University School of Hygiene and Pubic Hearth All rights reserved
Vol. 136, No. 12 Printed in U.S.A.
Air Pollution and School Absenteeism among Children in Mexico City
Isabella Romieu,1 Marlene Cortes Lugo,2 Silvia Ruiz Velasco,3 Sergio Sanchez,4 Fernando Meneses,5 and Mauricio Hernandez8
To determine the acute effects of ozone exposure, the authors conducted a short follow-up study of respiratory illness in a population of 111 preschool children frequently exposed to ozone levels that regularly exceed 0.120 parts per million (ppm). The children attended a private kindergarten in the southwestern part of Mexico City. Parents completed a questionnaire on demographic data, medical history, and potential sources of indoor air pollution. To determine the relation of ozone and respiratoryrelated school absenteeism, the authors used a logistic regression model for longitudinal data. During the 3-month follow-up, 50% of the children had at least one respiratoryrelated absenteeism period, and 11.7% had two or more. Children exposed for 2 consecutive days to high ozone levels (>0.13 ppm) had a 20% increment in the risk of respiratory illness. For children exposed for 2 consecutive days to a high ozone level and the previous day to low temperature (0.13 ppm). There was a significant interaction between high ozone exposure and low temperature (0.13 ppm) had a 20 percent increment in the risk of respiratory TABLE 3. Effect of a single day of ozone exposure on school absenteeism recorded among 111 preschool children of the southwestern part of Mexico City, 1990 Variable
Age Sex Passive smokingt Temperature}: Ozone§ Ozone x temperature
OR*
95% CI*
0.91 0.92 1.19 1.15 1.14 1.21
0.67-1.25 0.43-1.96 0.56-2.50 1.08-1.24 1.10-1.18 1.11-1.32
* OR, odds ratio ol school absenteeism tor respiratory Illness, estimated with model from Lang and Zeger approach; CI, confidence Interval. t At least one parent smoking at home. t Temperature Is a categorical variable (s5 1°C, >5.1°C); exposure on the previous day. § Ozone Is a categorical variable (5.1°C); exposure on the previous day. § Ozone Is a categorical variable (
Vol. 136, No. 12 Printed in U.S.A.
Air Pollution and School Absenteeism among Children in Mexico City
Isabella Romieu,1 Marlene Cortes Lugo,2 Silvia Ruiz Velasco,3 Sergio Sanchez,4 Fernando Meneses,5 and Mauricio Hernandez8
To determine the acute effects of ozone exposure, the authors conducted a short follow-up study of respiratory illness in a population of 111 preschool children frequently exposed to ozone levels that regularly exceed 0.120 parts per million (ppm). The children attended a private kindergarten in the southwestern part of Mexico City. Parents completed a questionnaire on demographic data, medical history, and potential sources of indoor air pollution. To determine the relation of ozone and respiratoryrelated school absenteeism, the authors used a logistic regression model for longitudinal data. During the 3-month follow-up, 50% of the children had at least one respiratoryrelated absenteeism period, and 11.7% had two or more. Children exposed for 2 consecutive days to high ozone levels (>0.13 ppm) had a 20% increment in the risk of respiratory illness. For children exposed for 2 consecutive days to a high ozone level and the previous day to low temperature (0.13 ppm). There was a significant interaction between high ozone exposure and low temperature (0.13 ppm) had a 20 percent increment in the risk of respiratory TABLE 3. Effect of a single day of ozone exposure on school absenteeism recorded among 111 preschool children of the southwestern part of Mexico City, 1990 Variable
Age Sex Passive smokingt Temperature}: Ozone§ Ozone x temperature
OR*
95% CI*
0.91 0.92 1.19 1.15 1.14 1.21
0.67-1.25 0.43-1.96 0.56-2.50 1.08-1.24 1.10-1.18 1.11-1.32
* OR, odds ratio ol school absenteeism tor respiratory Illness, estimated with model from Lang and Zeger approach; CI, confidence Interval. t At least one parent smoking at home. t Temperature Is a categorical variable (s5 1°C, >5.1°C); exposure on the previous day. § Ozone Is a categorical variable (5.1°C); exposure on the previous day. § Ozone Is a categorical variable (
