Pollutants from vehicle emissions and fossil fuels appear to hinder lung development and limit breathing capacity for a lifetime, according to data from an 8-year study of nearly 2,000 children.
The connection between air pollution and decreased lung function in adults has already been established from previous studies. In this study, researchers looked at 1,759 children as they progressed from 4th to 12th grade to determine what affect, if any, air pollution had on their lung development. The children lived in some of the most polluted areas in the Los Angeles area, as well as several less-polluted communities outside the area.
Beginning in 1993, the children's lung function was tested annually over the eight-year period. During the study, most of the boys doubled their lung function, and girls increased theirs by about two-thirds. However, children living in the most polluted communities had significant reductions in the volume of air that can be exhaled after taking a deep breath (forced expiratory volume) – up to 80 percent less than is expected for their age – even after factoring in their gender, size, medical conditions like asthma, and exposure to tobacco smoke.
This Children's Health Study found that children who grow up breathing polluted air are five times more likely to have low lung function than children living in communities with cleaner air.
For a Lifetime
"Lung development in teenagers determines their breathing capacity and health for the rest of their lives," says Dr. John Peters, Hastings professor of preventive medicine at the Keck School of Medicine. "The potential long-term effects of reduced lung function are alarming. It's second only to smoking as a risk factor for mortality. As lung function decreases, the risk of respiratory disease and heart attacks increases."
Because lung development typically stops at age 18, these children will likely have to live with weaker lungs and reduced breathing capacity for the rest of their lives.
The research team will continue to follow the study participants into their early 20s, when their lungs will be fully mature. They want to find out whether the participants will experience respiratory symptoms, and also if those who moved away from a polluted environment will show some improvement in lung function. Adults begin to lose lung function by one percent each year after age 20.
Researchers are unsure how air pollution may retard lung development. W. James Gauderman, Ph.D., associate professor of preventive medicine at the Keck School and lead author on the study believes chronic inflammation might play a role, with air pollutants irritating small airways on a daily basis. Scientists also suspect that air pollutants might dampen the growth of alveoli – tiny air sacs in the lungs.
Besides being more vulnerable to air pollution because their lungs are developing, children also breathe in more pollution than adults do. They take more breaths per minute and. pound for pound, breathe in more pollutants. Children are typically outdoors more than adults, which also increases their exposure. In addition, children at play often breathe through their mouths, losing the benefit of the filtering benefits of breathing through the nose.
Some Consequences
Deficits in lung function are associated with other short- and long-term effects. "If children or young adults with low lung function were to have a cold, they might have more severe lung symptoms, or wheezing," says Dr. Gauderman. "And they might have a longer disease course, while children with better lung function might weather it much better."
In the long-term, children with decreased lung function might have a higher risk for pneumonia and other respiratory infections than do older adults. |
