How Science Is
When the U.S. Environmental Protection Agency proposed tougher regulations seven years ago for tiny soot and smog particles known as airborne particulate matter, it knew solid research would be needed to back up the new rules. Not only did the Clean Air Act require EPA to review the current knowledge on air pollution every five years, the agency was also sure to face -- as is often the case with new regulations -- opposition from groups crying foul. Already, EPA had estimated from epidemiological studies that more than 15,000 premature deaths a year would be prevented by targeting smaller-sized particles. Still, much uncertainty remained about the relationship between particles and human health.
Agreeing that more research was needed, Congress directed the agency to seek guidance from the National Research Council on the matter, which convened a committee to issue a series of reports that EPA has relied upon to help set its particulate matter research priorities.
Recently issuing the fourth and final report of the series, the committee said that research confirms asthmatics and others with pre-existing respiratory ailments are more susceptible to complications caused by exposure to particulate matter -- in fact, studies have shown more particles deposit in their lungs than in those of healthy individuals. And new findings suggest that other groups may be at increased risk as well, including diabetics, seniors, and people with heart conditions.
"It's time to shift the focus from studying whether particulate matter causes adverse health effects to studying how the particles trigger injury, how people are exposed, and how much particulate matter is inhaled before adverse effects occur," said committee chair Jonathan Samet from the Bloomberg School of Public Health at Johns Hopkins University in Baltimore. Doing so will require EPA and others to develop better ways of tracking and characterizing the particles being emitted by different sources -- electric power plants, cars and trucks, industrial manufacturing, forest fires, and soil erosion are all culprits. Computer models that link pollution sources to atmospheric particulate matter levels in specific regions are needed too. EPA also should sponsor research aimed at understanding which chemical components of particulate matter are most hazardous, especially when mixed with other airborne pollutants.
"A lot has been learned in recent years," said Samet. "We can build upon that to reduce uncertainties further, keep decision-makers informed, and complete the foundation of evidence needed to protect public health." -- Bill Kearney
Research Priorities for Airborne Particulate Matter: IV. Continuing Research Progress. Committee on Research Priorities for Airborne Particulate Matter, Board on Environmental Studies and Toxicology, Division on Earth and Life Studies (2004, approx. 256 pp.; ISBN 0-309-09199-3; available from the National Academies Press, tel. 1-800-624-6242; $42.00 plus $4.50 shipping for single copies).
The committee was chaired by Jonathan Samet, professor and chair, department of epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore. The study was funded by the U.S. Environmental Protection Agency.