http://www.nytimes.com/2002/06/05/science/05PART.html?ex=1023940800&en =e5f0f8e505ec0911&ei=5040&partner=MOREOVER
Data Revised on Soot in Air and Deaths By ANDREW C. REVKIN Revisiting their own data with new methods, scientists who conducted influential studies that linked sooty air pollution with higher death rates have lowered their estimate of the risk posed by bad-air days. The findings do not challenge what is now a well-established link between air pollution and premature death. But the new analysis is highly likely to delay the final review of new regulations on small-particle pollution, officials of the Environmental Protection Agency said yesterday. The review was projected to end, and the new rules to take effect, by the end of next year. "This may clearly push it beyond that," a spokesman for the E.P.A., Joe Martyak, said last night. The fine particles in question come mainly from power plants and diesel engines, and the proposed rules have been at the center of a long legal, political and public-relations battle between private environmental groups and power plant owner and vehicle manufacturers. The researchers, at the Johns Hopkins University, have been distributing their new analysis to scientists and government officials by fax and e-mail. Yesterday, they set up a Web site, biosun01.biostat.jhsph.edu /~fdominic/research.html, that details their new findings. "This is a very important finding that needs to be probed," said Daniel S. Greenbaum, president of the Health Effects Institute, the organization that paid for the work and that was created by the E.P.A. and industry to conduct unbiased studies on contentious pollution issues. The studies in question, using data from 1987 to 1994, analyzed day-to-day small-particle pollution in 90 American cities and compared them to the death rates among the 100 million residents of those cities, accounting for other influences on mortality like weather and time of year. They found a pattern of more deaths, notably deaths from heart and lung problems, in the days after spikes in the concentrations of particles smaller than 10 microns, particles that can be deeply inhaled into the lungs and stay there. In the original analysis, the rise was 0.4 percent above the typical mortality rate for each jump of 10 micrograms of soot per cubic meter of air. In the new analysis, the increase is half that. The researchers said the change was small but significant. The average level in the average city is now about 24 micrograms a cubic meter. The work has been published for several years in a variety of leading journals like The New England Journal of Medicine and The American Journal of Epidemiology. The project, the National Morbidity, Mortality and Air Pollution Study, was given extra weight by policy makers because of the reputation of the Health Effects Institute and the Johns Hopkins group, led by Dr. Jonathan M. Samet, chairman of epidemiology at the public health school there. As part of a continuing effort to check for flaws, those scientists in recent weeks used a new method to look at their figures and obtained different results. They re-examined the original figures and found that the problem lay with how they used off-the-shelf statistical software to identify telltale patterns that are somewhat akin to ripples from a particular rock tossed into a wavy sea. Instead of adjusting the program to the circumstances that they were studying, they used standard default settings for some calculations. That move apparently introduced a bias in the results, the team says in the papers on the Web. The chairman of the Johns Hopkins biostatistics department, Dr. Scott L. Zeger, said other researchers who used the software, S-Plus, should check for similar problems. It is widely used for research in fields like pharmacology, genetics, molecular biology and stock-market forecasting, as well as serving as a mainstay of other environmental studies. Dr. Zeger and Mr. Greenbaum stressed that the new findings did not overturn the basic link between soot and illness. They also pointed to the recent publication of other studies on the long-term effects of soot that do not use the same analytical tools. Still, industry officials said the new findings called into question the validity of some research underlying the new federal standards. "This study is really one of the ones creating the path for the future on air-quality regulation," said Allen Schaeffer, executive director of the Diesel Technology Forum. The new results, Mr. Schaeffer said, show that "particle science is still evolving, and so are the analytical tools to look at it." Scientists involved with the soot standard said that there was much other evidence that pointed to the dangers of soot but that the errors in the Johns Hopkins work were still significant. "It certainly brings into question the precision of the data," said Dr. Jane Q. Koenig, a professor of environmental health at the University of Washington and a consultant involved with the soot review. "That's very unfortunate, because this research was supposed to be the re-analysis that was going to give us a lot of confidence." Senior government officials, including Dr. John D. Graham, President Bush's chief overseer of regulatory effectiveness at the Office of Management and Budget, said they had been told of the problems with the studies. Dr. Graham, who has often questioned the need for some rules, said that the apparent errors would "reduce significantly some benefit estimates fo reducing fine-particle pollution, but they do not call into question any of the key cause-effect relationships between pollution and premature death." ------------------------ Yahoo! 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