California Air Resources Board

SACRAMENTO – The landmark Children's Health Study, funded by the California Air Resources Board (ARB), is nearing to a close having produced numerous new findings on the effects of air pollution on children's health. This ten-year, $18 million study produced results showing how air pollution reduces children's lung growth and function, impacts respiratory health in asthmatic children, including new asthma cases and contributes to increased school absences.

ARB Chairman, Dr. Alan Lloyd said, "This study has added greatly to our basic understanding of air pollution's effects on our children's health and reinforced the need to continue our efforts to reduce the pollution affecting millions of children."

The study, conducted by researchers from the University of Southern California (USC), was the nation's first large-scale effort to study the effects of long-term exposure to outdoor air pollution in children, one of our most sensitive populations.

The study followed more than 5,500 children at 52 schools in twelve Southern California communities from elementary through high school to track how different outdoor air pollution exposures affect respiratory health. The majority of children enrolled in the program as fourth-graders and were followed through high school.

The major findings of the study were: 

• Significant lung function deficits are most closely associated with exposure to nitrogen dioxide, atmospheric acidity, PM 2.5 and PM10. This decreased lung development may have permanent adverse effects in adulthood.

• Children living in high ozone communities, who are especially active, are up to three times more likely to develop asthma.   

   

• Children living near roadways with high traffic experienced an increased risk for having been diagnosed with asthma.         

   

• Short-Term exposures to elevated ozone levels are associated with a significant increase (up to 1.3 million per year) in school absences from both upper respiratory illness with symptoms such as runny nose and lower respiratory illnesses such as asthma attacks.

   

• Children who move to cleaner communities with lower levels of PM have improvements in lung function growth rates. This means that even small reductions in air pollution can have immediate benefits to the long-term respiratory health of children living in polluted communities.

   

• Bronchitic symptoms are associated with exposure to nitrogen dioxide and the organic carbon fraction of  PM2.5 in asthmatic children.

   

• The strength of the air pollution effects are generally greater in children who spend more time outdoors, and

   

• Results from the study suggest that boys in general are more susceptible to adverse respiratory symptoms and asthma outcomes than girls. Girls appear to have greater susceptibility for adverse effects on lung function development. There is limited evidence supporting sex differences in responses to ambient air pollutants; however, children of both sexes appear to have adverse respiratory effects of exposure to current levels of air pollution.

Outdoor pollution monitoring tracked levels of ozone, nitrogen oxide, acid vapor and particulate matter over the ten-year study. In addition, limited indoor pollution measurements were taken at schools and in homes. Each spring, the lung function of each child was tested and annual questionnaires collected information about respiratory symptoms and diseases, physical activity, time spent outdoors, and factors such as parental smoking, and mold and pets in the household.

The 12 communities studied were: Atascadero in San Luis Obispo County; Lompoc and Santa Maria in Santa Barbara County; Lake Arrowhead and Upland in San Bernardino County; Lancaster, Long Beach and San Dimas in Los Angeles County; Lake Elsinore, Mira Loma and Riverside in Riverside County; and, Alpine in San Diego County.

A final report of the study is being produced and will be posted to the ARB website for downloading, along with a list of the 72 published scientific papers produced by the USC researchers. The study has been cosponsored by the U.S. Environmental Protection Agency, South Coast Air Quality Management District and other local air pollution control districts.

To view a copy of the report, click here.