Researchers at the Harvard School of Public Health have concluded that people living in more air-polluted areas have a 15 to 17 percent higher risk of death than those living in less polluted areas.

The study, published last week in the American Journal of Respiratory and Critical Care Medicine, took over a decade to complete and included pollution data from over 500,000 residents in 151 U.S. cities.

"The bottom line is that there is a substantial increase in the risk of cardiopul-monary-disease-related death in polluted cities," said co-author, who was a visiting scientist at the School of Public Health at the time of the study and is a professor at Brigham Young University.

According to Douglas W. Dockery, associate professor of environmental epidemiology at the School of Public Health, the study confirms scientists' previous suspicions about air pollution.

The results expand on findings from the Harvard Six City Study, a smaller air pollution study conducted by Pope and Dockery in December 1993.

The earlier study, published in The New England Journal of Medicine after 18 years of research, found high mortality rates due to air pollution in six cities: Topeka, Kansas; Portage, Wisconsin; Watertown, Massachusetts; Kingston, Tennessee; St. Louis, Missouri; and Stoubinville, Ohio.

"[The recent study] confirms the results of the earlier study by extending the data to all the major U.S. cities," Pope said. "The study is so large that it controls for such confounding factors as sex, race and age."

Dockery said their findings may help the Environmental Protection Agency (EPA) set new pollution standards.

"The EPA has been aware of four studies for quite a long time," Dockery said. "As the EPA undergoes its next review and reevaluation, the recent findings on measurable health effects will be evidence suggesting the need for new standards."

The two researchers plan to continue their work in this field by getting "a better feel for the biological mechanisms involved in these associations," said Pope.