Deaths Rise with Ground-Level Ozone Warning

Medical Authors and Editors: Barbara K. Hecht, Ph.D. and Frederick Hecht, M.D.

November 17, 2004 -- A new study has found that exposure to ground-level ozone is associated with an increased risk of death in the US. Increases in the ozone contribute to thousands of deaths every year.

The risk of death is similar for adults of all ages but slightly higher for people with respiratory or cardiovascular problems. The increase in deaths occur at ozone levels below the clean air standards of the Environmental Protection Agency (EPA).

Study from Hopkins & Yale

The new study was done by researchers at the Yale University School of Forestry and Environmental Studies and the Johns Hopkins Bloomberg School of Public Health. Their report was published today in the Journal of the American Medical Association.

National air quality and mortality data from 95 large urban areas for the years 1987-2000 were used to investigate whether daily and weekly exposure to ground-level ozone was associated with mortality. The researchers adjusted for particulate matter, weather, seasonality, and long-term trends.

It was discovered that an increase of 10-ppb (10 parts per billion) in the daily ozone levels for the previous week was associated with a 0.52% increase in daily mortality. This corresponds to 3,767 additional deaths annually in the 95 urban areas studied.

Comments on the Study

"Our study shows that ground-level ozone is a national problem, which is not limited to a small number of cities or one region. Everyone needs to be aware of the potential health risks of ozone pollution," said Dr. Francesco Dominici, an author of the study from Hopkins.

"Cars and smokestacks produce gases that then undergo a chemical transformation, becoming ozone in the air," said Dr. Michelle Bell, another author of the study from Yale.