Background: The objective of the study was to describe the prevalence of obesity among Mexican children and its impact on ventilatory lung function.
Methods: We studied cross-sectionally 6784 students between 8 and 20 years of age attending schools located <2 km away from ten air pollution monitors located throughout metropolitan Mexico City. The comparison group was made up of 1924 Mexican-Americans of the same age, studied during the NHANES-III examination, which included information on spirometry and body mass index (BMI).
Results: Of all our subjects, 9.7% had a BMI >95(th) percentile of CDC growth charts (compared to 15.1% in Mexican-Americans) and 6.6% fulfilled the obesity criteria of the International Obesity Task Force (vs. 12.2%). Obesity was related to male gender, asthma and passive smoking. At the same height and gender, lung function was higher in Mexicans than in Mexican-Americans, perhaps due to altitude. In children 8-11 years of age, lung function increased in heavier subjects but, in older children and youths, function reached a plateau and decreased among children with highest BMI (inverted U pattern, seen in adults).
Conclusions: Obesity is higher in Mexican-American children and youths than in Mexicans. Spirometric function is affected adversely by obesity, especially in young people.