Health impacts of air pollution on morbidity among children of Ciudad Juárez, Chihuahua, México

Various studies conducted in Latin America provide evidence of the adverse effect of air pollution on health in different population groups. Few studies, however, have focused on young children and none have evaluated the impact of air pollution on groups of children that may be more vulnerable because of poor living conditions. We conducted a study in Ciudad Juárez, Mexico, a city located on the US-Mexico Border in the state of Chihuahua, to determine the impact of the air pollutants PM10 and ozone on the respiratory health of children. One of the main characteristics of Ciudad Juárez is the migratory flow across the border, mainly due to the increasing maquiladora industry and the rapid increase in the population with unplanned settlement. In this study, we observed significant associations between ozone ambient levels and respiratoryrelated emergency visits by children. These associations were present for upper respiratory infections and asthma in all age groups. However, in children aged five years or less, ozone exposure was also related to lower respiratory infections (LRI) with a four-day lag. An increment of 20 ppb in the maximum 8-hr moving average four days prior to the visit was related to a 12.7% increase in the risk of LRI (95% CI 4.2% to 21.9%). Considering an increase of 20 ppb in 1-hr daily maximum over five days prior to the visit, the risk was 15% (95% CI 2.3% to 29.4%). No association was observed with PM10 ambient levels. These results remained similar in multipollutant models including ozone as well as PM10. Overall, ambient air pollutants were not related to respiratory deaths in our population of children. However, there was some suggestion that PM10 ambient levels might increase the risk of respiratory mortality among infants (>1 month to 1 year). When data were stratified by socioeconomic status (SES), an increase in respiratory mortality was observed among infants from the lowest SES group (tables 20-21). Among infants aged one month to one year, a 20 μg/m3 increase in PM10 24-hr average on the previous day was associated with a 62% increase in respiratory mortality (95% CI 10% to 140%). When an increase of 20 μg/m3 was observed on the two previous days, the risk of death was increase by 82% (95% CI 1% to 228%). However, these estimates were based on only 41 deaths. No increased mortality was observed in the higher SES. These results remained similar in multipollutant models including ozone as well as PM10. Mexico, as well as other developing countries, has a large urban population of children who live in poor conditions. Children, in particular young children, are a sector of the population susceptible to environmental threats because of their behavior and a reduced capacity to metabolize toxic substances (21). In addition to physiologic vulnerabilities, many children in Latin America have great social vulnerabilities related to poverty, malnutrition, and poor environment that both increase their exposure to contaminants and their susceptibility to the effects of contaminants (22). In addition, increases of respiratory morbidity and mortality were observed at air pollution levels commonly observed in urban areas in the region. Therefore, our results emphasize the need for the implementation of cost effective interventions to control existing air pollution problems and prevent the existing situation from worsening