New Findings Link Reduced Lung Growth and Air Pollution

This page updated October 7, 2002

An analysis of recent data from the Children's Health Study (CHS) has again shown that the lungs of children in high-pollution communities develop more slowly and do not move air as efficiently. The recent data are published in the American Journal of Respiratory and Critical Care Medicine July 1, 2002 (Volume 166 Pages 76- 84).

The CHS annually measured the lung function of 1,700 fourth-graders enrolled in 1996, monitored the communities' air pollution for four years until 2000, and analyzed the relationships between their lung function growth and the levels of six pollutants.

The new findings of slower lung growth in more polluted communities generally agree with the lung growth findings for the first group of fourth-graders the CHS enrolled in 1993. The analysis found that higher exposures to acid vapor, ozone, nitrogen dioxide, very small particles that can be breathed deeply into the lungs, and elemental carbon in very small particles significantly decreased measures of lung growth and functioning.

Acid vapor was most consistently associated with slower growth and decreased lung function in both groups of children.

The lungs of children in the 1993 group were, surprisingly, not affected significantly by ozone; in contrast, children in the 1996 group with higher ozone exposures exhaled at significantly lower maximum rates during testing.

The slower lung growth associated with higher exposures to elemental carbon may indicate a specific respiratory effect of diesel exhaust; diesel engines are a major source of elemental carbon in very small particles in Southern California.

The negative effects of pollution exposures were stronger in the group of children who spent more time outdoors in the afternoon, compared to children who spent less time outdoors, which is further evidence of the relationship between exposures and adverse effects. Children who spend more time outdoors in high-pollution communities are more likely to experience short-term exposures to high concentrations of pollutants.

Slower lung growth over a period of several years, now confirmed in two different groups of children, is the strongest evidence of a chronic effect of air pollution on children's respiratory health. Lung function reaches a maximum in young adults; children whose lungs have grown more slowly may have lower maximum lung function, a question of intense interest to respiratory researchers.

Adults with lower maximum function may be more susceptible to respiratory diseases and chronic problems as they age. The Children's Health Study investigators will be following the children into young adulthood to obtain valuable data on maximum lung function.

Children's health Study