Study Links Air Pollution and Asthma

SACRAMENTO -- January 31, 2002. A 10 year study of children funded by the California Environmental Protection Agency's Air Resources Board (ARB) and conducted by the University of Southern California (USC) has produced the strongest evidence to date that ozone, commonly know as smog, can cause asthma in children.

ARB Chairman Dr. Alan Lloyd said, "We've known for some time that smog can trigger attacks in asthmatics. This study has shown that ozone can cause asthma as well." Previous evidence has shown that ozone, one of the most health-damaging air pollutants, can aggravate existing cases of asthma. The new ARB-USC study, however, points strongly to ozone as a cause in the development of asthma in young people who did not previously have the disease.

The study compared new asthma cases in 3,535 children who were followed over five years in 12 Southern California communities to determine the potential health damage caused by growing up in polluted air. Six of the communities had higher than average ozone concentrations while six had lower than average concentrations. Researchers further refined the study by looking at children who played up to three team sports.

The study showed that children in the high ozone communities who played three or more sports developed asthma at a rate three times higher than those in the low ozone communities. Because participation in some sports can result in a child drawing up to 17 times the "normal" amount of air into the lungs, young athletes are more likely to develop asthma. This link to asthma follows additional results of an eight-year, $18 million study released early last month. The previously released results found that most children who moved to communities with higher levels of particulate matter (measuring less than 10 microns in diameter- PM10) showed decreased rates of lung function growth compared to those who moved to communities with lower levels of PM10.

After reviewing the study, Dr. Lloyd noted recent efforts to weaken some environmental regulations. "This study illustrates the need not to retreat but to continue pushing forward in our efforts to strengthen air pollution regulations," Dr. Lloyd said. In order to combat air pollution, the ARB has adopted environmental justice policies which will help strengthen outreach and education efforts in all communities, especially low-income and minority communities, so that all Californians can fully participate in the public processes and share in the air quality benefits.

For more information about the Children's Health Study see:

For explanation about how asthma works, see