Air Pollution Causes Lung Disease In School-Age Children

Researchers reached that conclusion after evaluating standard chest x-rays of 241 southwest metropolitan Mexico City children and another 19 from a small coastal town. The city children were exposed daily to high levels of a variety of pollutants, compared to the absence of such pollution in the coastal town comparison group.

The new research is being presented Thursday November 29th in Chicago at the 87th Scientific Assembly and National Meeting of the Radiological Society of North America.

The study investigators were led by Dr. Lillian Calderon-Garciduenas from the department of environmental sciences and engineering at UNC-CH and the National Institute of Pediatrics in Mexico City and Dr. Lynn A. Fordham, associate professor and section chief of pediatric imaging at the University of North Carolina at Chapel Hill School of Medicine.

"These were a large number of very healthy, middle-class children who received excellent health care. Dr. Calderon screened out any of the candidate children with asthma," Fordham said. "While I think these are preliminary findings, they appear to have important implications for the effects of air pollution on the lungs of otherwise healthy children."

Fordham points out that the chest x-rays from Mexico were interpreted by radiologists at UNC who had no knowledge of where the children lived. "We looked at the kids in a blinded fashion and with no knowledge of Dr. Calderon's project," she said. "We were able to separate out those who were exposed to air pollution and those who were not."

Excessive inflation (hyperinflation) of both lungs was found in 63 percent of the city group. About 52 percent of the city children showed an abnormal amount of interstitial markings in their lungs, changes that may be predictive of future lung abnormalities.

The study also found abnormalities in CT scans obtained in 25 of the children whose chest x-rays were the most abnormal. Mild wall thickening of bronchial air passages was seen in 10 CT's, four showed unusually prominent central airways, eight children had air trapped in their lungs, and one child had a lung nodule.

Further statistical analysis pointed to a significant link between hyperinflation, interstitial markings and exposure to the polluted atmosphere of southwest metropolitan Mexico City. All children in the Mexico City study group lived within a 10-mile radius of a pollution monitoring station and ozone levels were recorded for the year the children were recruited into the study. On average, during the 20-month study period, ozone levels exceeded air quality standards more than four hours per day. Some small particles of solids, or particulate matter (PM), were above U.S. standards.

"The children studied were very active, and many of them spent hours playing soccer in the later afternoon - when pollutant levels are at their peak," Fordham said. "I think the study may contain findings that are concerning to parents. They indicate that air pollution may cause lung disease in children. Children might be safer staying indoors in the after-school hours on days when ozone levels are high."