Air Pollution Linked to Lung Disease in Children
X-rays reveal abnormalities in Mexico City kids
WEDNESDAY, Nov. 28, 2001 (HealthDayNews) -- American researchers who found inflammation and irregularities in lung X-rays of schoolchildren in Mexico City believe they've found the culprit: air pollution.
And they say the findings suggest otherwise healthy, middle-class children in part of that city face a higher risk of lung disease.
Lead investigator Dr. Lynn Fordham, chief of pediatric imaging at the University of North Carolina, says the findings, while preliminary, may be a wake-up call to parents and public policy makers. Fordham presents the findings at today's 87th Scientific Assembly and National Meeting of the Radiological Society of North America, in Chicago.
The researchers enrolled 260 healthy Mexican children, none of whom had asthma or other risk factors for respiratory problems, such as exposure to tobacco smoke in their homes. The children were from middle-class families, had nutritious diets, access to health care and were normal weight at birth -- all of factors that made lung problems unlikely.
"They ought to be healthy, and they ought to be normal, but they're not," says Fordham.
Of the 260 children, 241 came from southwest metropolitan Mexico City, a region known for its high daily levels of air pollutants, and within 10 miles of a pollution monitoring station, which recorded ground-level ozone levels while the children were enrolled.
During the 20-month study, ozone levels exceeded U.S. National Air Quality Standard levels for 4.75 hours each day. Levels of particulate matter small enough to lodge in the lungs also were above U.S. standards.
The 241 children from the city were compared to 19 children from a small, relatively unpolluted coastal town in Mexico.
Chest X-rays of all the children were examined by two experts specializing in children's X-rays who scored the images using standardized scales of lung expansion and marks within the lungs.
Children whose X-rays showed the most obvious abnormalities underwent computed tomography (CT) scans, which use very focused X-ray beams to take pictures inside the body.
The regular X-rays found children living in Mexico City were far more likely to have abnormal X-rays: 151 showed over-expansion (hyperinflation) of the lungs, and 126 had abnormally high levels of markings in their lungs.
Of the 25 children who were given a CT scan, 10 had mild wall thickening of the bronchial air passages; four had abnormally prominent central airways, and eight had air trapped by inflammation in sections of their lungs. One child had a lung nodule.
"It suggests that air pollution can cause lung disease in these kids. These kids might go on to have long-term lung disease, like chronic obstructive pulmonary disease," says Fordham.
She says pollution peaks generally occur in late afternoon while "the kids are out of school, and they're outside playing soccer. They're really getting a significant exposure."
She says several regions of the United States, including southern California, the Northeast corridor and Ohio River Valley cities, all have high pollution levels. "You have to wonder what's happening to the kids here in the United States." She says parents may want to consider keeping their children indoors during afternoons when ozone levels are high.
Dr. Carol Rumack, professor of radiology and pediatrics at the University of Colorado Health Sciences Center, in Denver, says while the data doesn't allow scientists to draw a direct line between air pollution and lung disease in children, "you could assume that what's happening is when they're exercising, they're taking in the polluted air." She says if the children are playing, they are most likely breathing deeply through their mouth, which is much less efficient than the nose at filtering out particulate pollution.
"We don't actually know what it will lead to, but at some threshold they're going to have potentially more wheezing, more coughing -- chronic lung disease symptoms. They might have more potential to be an asthmatic," Rumack says.
Fordham also raises questions about a pollution link to the growing number of children with asthma. She notes that American children are also exposed to more indoor air pollution, such as tobacco smoke, molds and mildews.
Fordham says her findings raise the issue of how public policy should tackle air pollution levels. "Despite the cost, we need to focus on efforts to reduce air pollution. It's going to be a huge, long-term impact on society."
She says since the study looked at middle-class children, who have health advantages, "you have to be very concerned about how low-income kids will handle the air pollution exposure."
Rumack says, "the concern would be about children in inner cities, where there's a lot of traffic and high pollution."