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Studies Bolster Dirty Air's Ill Effects on Health

Clean measures cut death rate, living near traffic raises it

THURSDAY, Oct. 17, 2002 (HealthDayNews) -- Long after the noise of nearby traffic fades into toleration, busy roads continue to take their toll on human health.

Dutch scientists report in this week's issue of The Lancet that living near heavy traffic seems to increase the risk of early death from heart and lung disease, thanks to pollutants in auto exhaust.

The good news, experts say, is that cleaning up the air appears to pay off in fewer pollution-related deaths almost immediately. An unrelated study appearing in the same issue of the journal showed that a 1990 ban on coal sales in Dublin, Ireland, was followed by 10 percent to 15 percent drops in fatal heart and lung ailments, even after accounting for a general trend toward better health nationally.

While there have been studies that documented the damage pollution has caused, there has been little research to show that cleaning up the air can save lives, says Douglas Dockery, a co-author of the paper and an environmental health expert at the Harvard School of Public Health in Boston. "Within a few months we can see a reduction in death rates."

The link between smoggy skies and human disease has become increasingly clear.

One recent study of city dwellers showed that every 10-microgram elevation in "fine particulate matter" -- bits about the size of red blood cell -- pushed up the overall risk of death as much 4 percent. Deaths from cardiopulmonary disease rose 6 percent, while lung cancer mortality rose 8 percent.

Another study found that even two hours spent breathing heavy loads of ozone and fine-particle pollution can narrow the arteries of healthy people by between 2 percent and 4 percent.

In the Dutch work, a team led by Gerard Hoek, an environmental health expert at Utrecht University, looked for the effects of traffic pollution in 5,000 Dutch men and women between 1986 and 1994. Those who lived within 50 meters of a major thoroughfare and 100 meters of a freeway had nearly twice the risk of dying of heart and lung-related illness during the period than others in the study, even after accounting for factors such as smoking history and social and economic status.

The overall risk of death also seemed somewhat higher for people living near traffic, though the increase wasn't statistically significant.

Hoek and his colleagues point out that despite the impact of pollution on health, the risk of premature death from smoking is far higher. Even so, they wrote: "Long-term exposure to traffic-related air pollution may shorten life expectancy."

C. Arden Pope III, an economist at Brigham Young University who studies pollution, says the Dutch work suggests that "we may be underestimating the amount of mortality risk that can be explained by spatial differences in pollution."

Pope, co-author of an editorial accompanying the journal articles, calls both reports "fascinating" and says the link between dirty air and poor health "can't be explained away as some spurious set of associations because it holds up so many places using so many different study designs."

In the Irish study, researchers in that country and the United States analyzed rates of respiratory and cardiovascular deaths before and after the 1990 ban on the sale and distribution of bituminous coal burned for heat. Coal smoke is rich in soot and sulfur oxides, which irritate the lungs.

In the six years after the law passed, the amount of black smoke clouding the Emerald Isle's capital city fell 70 percent, compared with a six-year period leading up to the ban. At the same time, rates of deaths from all non-traumatic causes dropped by nearly 6 percent; those from heart and lung ailments fell 10 percent and 15 percent, respectively. In other words, the researchers say, 116 fewer Dubliners were dying each year from respiratory distress and 243 heart deaths were spared since the law was enacted.

Dr. Norman H. Edelman, a consultant for the American Lung Association and dean of State University of New York-Stony Brook School of Medicine, says the latest research supports the mounting evidence that "particulates have a major impact on excess mortality." The situation is akin to the early skepticism that smoking was a health hazard, Edelman adds. "It was pooh-poohed at first, but now it's incontrovertible."

Edelman calls the Dutch traffic study "compelling and important," but says that current policies in the United States are making the problem worse. Environmentalists have accused the Bush administration of diluting the Clean Air Act in favor of industrial polluters, and have lamented the classification of sport utility vehicles as light trucks instead of cars, exempting them from stricter fuel economy laws.

What To Do

For more on healthy breathing, try the American Lung Association. Learn about pollution from the Environmental Protection Agency or the National Resources Defense Council.

SOURCES: Douglas Dockery, D.Sc., professor, environmental epidemiology, Harvard School of Public Health, Boston; C. Arden Pope III, Ph.D., professor, economics, Brigham Young University, Provo, Utah; Norman H. Edelman, M.D., scientific consultant, American Lung Association, vice president, Health Science Center, and dean, State University of New York-Stony Brook School of Medicine; Oct. 19, 2002, The Lancet
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