RESUMEN
A study was conducted in two elementary schools in Mexico City to determine values for pulmonary function tests in school-aged residents of Mexico City. The schools were located in Xalostoc, a highly industrialized area of Mexico City, and San Lorenzo, a suburban area of the city. Although data regarding atmospheric pollution were not available, there is an acknowledged higher level of macroenvironmental air pollution in Xalostoc. Pulmonary function tests were performed on 468 children in San Lorenzo and 405 children in Xalostoc. No differences between residents of the two communities for acute or chronic respiratory conditions were detected by questionnaire. The pulmonary function data demonstrate that boys have larger forced vital capacities (FVC) and forced expiratory flows over the middle half of the FVC (FEF25-75) than girls. Slopes of regression lines for FVC but not for FEF25-75 are greater in boys and girls from Xalostoc than in boys and girls from San Lorenzo. This suggests that young children from Xalostoc may experience ill effects of air pollution but develop catch-up growth later. There were no important community or gender effects on slopes of regression lines for height and weight on age. In general, the regression lines for FVC and FEF25-75 were below regression lines reported for children of Mexican ancestry living at sea level.