Scientists Find New Dangers in Tiny but Pervasive Particles in Air Pollution
Share with others:
Fine atmospheric particles -- smaller than one-thirtieth of the diameter of a human hair -- were identified more than 20 years ago as the most lethal of the widely dispersed air pollutants in the United States. Linked to both heart and lung disease, they kill an estimated 50,000 Americans each year. But more recently, scientists have been puzzled to learn that a subset of these particles, called secondary organic aerosols, has a greater total mass, and is thus more dangerous, than previously understood.
A batch of new scientific findings is helping sort out the discrepancy, including, most recently, a study led by scientists at the University of California, Irvine, and the Pacific Northwest National Laboratory in Richland, Wash., that is scheduled to be released on Tuesday. It indicates that the compounds' persistence in the atmosphere was under-represented in older scientific models.
"If the authors' analysis is correct, the public is now facing a false sense of security in knowing whether the air they breathe is indeed safe," said Bill Becker, of the National Association of Clean Air Agencies.
Taken together, the findings of the new study and of a handful of others published in the past two years could mean that two decades' worth of pollution-control strategies -- focused on keeping tiny particles from escaping into the atmosphere -- have addressed only part of the problem.
Scientists and regulators say that new models, strategies and technologies would be needed to address the secondary organic aerosol particles, which are formed not during combustion but later, in the wake of interactions between pollutants and natural chemical compounds.
Paul Shepson, a professor of analytical and atmospheric chemistry at Purdue University and one of the reviewers of the Irvine paper, called it "highly significant in scientific terms," adding that current models of fine particulates "grossly underpredict" their density, "sometimes by as much as a factor of 10."
A former regulator agreed. "There's no doubt this is important stuff," said Jeffrey R. Holmstead, who ran the Environmental Protection Agency's air and radiation program during the administration of President George W. Bush. "It may be harder than we thought" to clean the fine particles out of the air and protect public health, he said, "but if we really know what's causing it, we can focus our efforts more."
First Published February 19, 2012 12:01 am
