Dec. 14 (HealthDay News) -- Children with asthma who are exposed to traffic pollution are at increased risk for respiratory problems and reduced lung volumes, says a study that looked at children in the Mexican border town of Ciudad Juarez, a crossing point into the United States.

"Major cities along the northern and southern U.S. borders often have high levels of vehicular traffic flows, especially at the border crossing points. Vehicular traffic emissions from the high density of border crossing traffic may be negatively affecting the health of populations who live in nearby areas," study lead author Dr. Fernando Holguin, assistant professor of pulmonary medicine at Emory University School of Medicine, said in a prepared statement.

Holguin and colleagues recruited 200 asthmatic and non-asthmatic children, ages 6 to12 years, who lived in Ciudad Juarez. For one year, the researchers measured traffic density and traffic-related pollutants near the children's homes and schools. For four months, they evaluated each child's lung function and respiratory symptoms.

The researchers found that children with asthma -- but not those without asthma -- were affected by living in homes in areas with heavy traffic. These children had higher levels of exhaled NO, as well as reductions in both lung volume and airflow.

Living within 50 meters of a road with heavy traffic increased the risk of respiratory symptoms in asthmatic children by more than 50 percent, the researchers concluded.

"Our results show that close proximity to vehicular traffic-related emissions, either at home or at school, can lead to chronic effects in the respiratory health of children with asthma," Holguin said.

The findings "may have implications for asthmatic children residing in these conditions -- especially among those who may not be adequately controlled with medications -- for they may be more susceptible to vehicular emissions."

The study was published in the second issue for December of the American Journal of Respiratory and Critical Care Medicine.

SOURCE: American Thoracic Society, news release, Dec. 14, 2007