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University of Southern California Children's Health Study
Summary
A team at the Keck School of Medicine, University of Southern California, has been conducting the Children's Health Study (CHS) since the early 1990's. The study's research findings on long-term effects of air pollution on children's lungs, coupled with USC's public outreach efforts, have led to broader public awareness and public health actions to protect children's health.
The CHS involves 11,000 children and is aimed at investigating the causes of childhood respiratory diseases, emphasizing the long-term health effects of air pollution. Key research findings show that:
Current levels of air pollution have chronic, adverse effects on lung growth leading to clinically significant deficits in 18-year-old children.
Air pollution affects both new onset asthma and asthma exacerbations.
Living in close proximity to busy roads is associated with increased risks for prevalent asthma.
Residential traffic exposure is linked to deficits in lung function growth and increased school absences.
Differences in genetic makeup affect these outcomes.
Results
The findings demonstrated an association between breathing polluted air in Southern California and significant chronic deficits in lung function among adolescent children. Researchers observed air pollution effects on lung function level at study entry (youngest age 10yrs), on 4-year lung function growth (age 10-14 years), on 8-year lung function growth (age 10-18 years), and on the maximum rate of lung function growth during adolescence (over the study period).
Air pollution exposure over the 8-year (from fourth grade to twelfth grade) study period was also linked to clinically significant deficits below 80% predicted] in lung function at age 18 years.
There were three to five times more children with clinically significant deficits in lung function living in communities with high outdoor air pollution levels compared to communities with low pollution levels. In a subset of children who moved away from their original study community.
There were consistent associations of changes in lung function growth rates with corresponding changes in ambient air pollution exposure between childrens’ former and current communities of residence.
The pollutants most closely associated with lung function deficits were NO2, acids (either inorganic, organic, or a combination of the four acids monitored), PM10, and PM2.5.
Asthma
The study demonstrated the effects of air pollution on both new onset asthma and asthma exacerbations. Prior to the performance of the CHS, the prevailing scientific view was that air pollution made existing asthma worse but that it did not cause new cases to develop.
Study data showed that new cases of asthma are much more likely to occur in high ozone communities, especially among those children who exercise regularly and at elevated levels.
The analyses regarding exposure to traffic-related air pollution have found associations between proximity to high traffic density (a marker for pollutant exposure) and increased risks for prevalent asthma among children.
The study demonstrated that air pollution is related to bronchitis symptoms and that asthmatics are more likely to be affected than non-asthmatics.
Conclusions
Current levels of air pollution in Southern California are associatedwith several serious health effects that are costly to children’s health and to the state.
Lung function was found to be consistently associated with a package of highly correlated pollutants that include particulates, NO2, and acids, but not ozone.
The impact of vehicle-related pollution on children’s lung function is likely to have life-long adverse health.
There is strong evidence linking ozone exposure to new cases of asthma (the most common chronic disease of childhood) and these associations extend to pollution levels below current ambient air standards and may exert significant health effects.
Taken as a whole, the results from the Children’s Health Study should provide scientific support for aggressive and accelerated efforts to achieve clean air for our children to breathe.
Online documents:
About the Childrens Health Study Word 03.doc
Effect of traffic exposure on lung development in The Lancet.doc
Exposure to Traffic and Onset of Myocardial Infarction.doc
Southern California Environmental Health Science Center Word 03.doc
USC Childrens Environmental Health Center Word 03.doc
Children’s Health Study Final Report
California Air Resources Board
Smog May Cause Lifelong Lung Deficits (from USC Children’s Health Study)
New England Journal of Medicine