When ozone goes up in cities, even for short periods at levels below current regulatory standards, so does the death rate, according to an article in Wednesday’s Journal of the American Medical Association.

The study, looking at 95 large urban communities over a 14-year period, is one of the largest to investigate the relationship between ozone and mortality, Dr. Michelle L. Bell told AMN Health.

Bell, at Yale University in New Haven, Connecticut, and colleagues at Johns Hopkins University in Baltimore, obtained data from the National Center for Health Statistics from 1987 to 2000, and air-pollution data on ozone from the US Environmental Protection Agency.

A 10 part-per-billion (ppb) increase in daily ozone levels over a previous week was associated with an average increase of 0.52 percent in daily non-injury-related deaths, the team reports.

That figure translates to an additional 319 premature deaths annually for New York City, the region with the highest ozone-related mortality, for each 10 ppb increase in ozone, and an increase of 3767 deaths annually for all 95 urban areas.

There appear to be regional variations, Bell pointed out. “We need to look at this in more depth to see if ozone has stronger effects in some parts of the country than in others.”

It may be, she said, that certain factors specific to different cities, such as income levels, racial distributions, or even the use of air conditioning could affect the mortality risk associated with ozone pollution.

The investigators noted that death rates increased at ozone pollution levels below current regulatory cut-offs. Bell pointed out that the EPA, a co-sponsor of this study, is mandated by the Clean Air Act to periodically review air pollution standards. The results of her team’s study and others may induce the agency to strengthen its ozone standards.

SOURCE: Journal of the American Medical Association, November 17, 2004.