Study Links Ozone, Mortality in Urban Areas

More people died in urban areas when ground-level ozone was higher during the previous week, researchers at Yale School of Forestry and Environmental Studies and Johns Hopkins report in the November 17 Journal of the American Medical Association.

The study, funded by the United States Environmental Protection Agency (EPA), was conducted from 1987 to 2000 and drew a connection between short-term changes in ground-level ozone, a common outdoor pollutant, and mortality in 95 large urban areas, covering 40 percent of the U.S. population.

“This is one of the largest ozone pollution studies ever conducted,” said Michelle Bell, lead author and assistant professor of environmental health at Yale.

“By linking day-to-day variations in ambient ozone levels and daily number of deaths in each of the urban areas, and pooling the results across the 95 urban areas, this study provides strong evidence of short-term effects of ozone on mortality,” said Francesca Dominici, senior author and associate professor of biostatistics at Johns Hopkins.

Bell said that a reduction of 10 parts per billion, or roughly 35 percent of the average ground-level ozone on any particular day, could save an average of 4,000 lives per year in the 95 urban areas. “This actually underestimates the total impact of ozone on mortality, because it only captures the mortality impact associated with high ozone levels in the past few days, not the impact associated with a lifetime exposure to high ozone levels,” said Bell. “This reduction of ozone is modest given available technology.”

The primary sources of ozone pollution are vehicles, industrial sources and power plants. Bell said by driving less, taking public transportation, reducing energy consumption and staying indoors on hot days when the ozone level is high would lessen ozone-related mortality and improve the health of people who suffer from respiratory illness.

Other authors on the study included Aidan McDermott, Jonathan Samet and Scott Zeger of the Johns Hopkins Bloomberg School of Public Health.

Citation: JAMA Vol. 292 No. 19

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