How Deadly Is Air Pollution?
Merline, John, Consumers' Research Magazine
The day before Thanksgiving last year, the Environmental Protection Agency (EPA) made a troubling announcement. Tens of thousands of people each year are being killed by microscopic particles emitted from smokestacks, car exhaust pipes, backyard barbecues, chimneys, and the like.
"The scientific evidence indicates that very small particles pose the greatest risk to human health and are most likely to lead to respiratory complications, including premature death," said EPA head Carol Browner.
The technical term for these particles is PM 2.5. The number refers to the size of the particle measured in microns. For reference, a human hair measures about 70 microns wide. The EPA that day announced plans to set tough new air pollution standards for PM 2.5, adding them to the list of many other air pollutants the EPA regulates--smog, sulfur dioxide, lead, and so on. The new standards, Browner said, would save 20,000 lives a year.
Yet almost as soon as the EPA announced its plans, the American Lung Association (ALA) and environmentalist groups complained that the agency didn't go far enough. In a report released in January, the ALA argued that the new standard "would still leave 89 million people potentially exposed to dangerous levels of deadly particle pollution." The Natural Resources Defense Council claimed that a striking 60,000 people die each year from fine particle air pollution. In other words, the EPA's new rule would save only a third of those killed each year.
Where are these worrisome figures coming from? The EPA and environmentalist groups say that there is a solid wall of scientific evidence proving the deadly effects of relatively low levels of fine particle air pollution. "The scientific findings are clear," Browner said. "The question is not one of science. The real question is one of judgment."
But many scientists have challenged that claim. They've looked at the same data and have concluded that the scientific evidence that PM 2.5 is killing anyone, let alone 60,000 people a year, is weak.
"They are trying to espouse a certainty that is simply not warranted by the science at this time," says Suresh Moolgavkar, a scientist at the Fred Hutchinson Cancer Research Center in Seattle, Wash., who has reviewed some of the air pollution studies.
If these skeptics are right, the EPA's new rules could force consumers to pay billions of dollars each year for little or no health benefit.
The skeptics include the very scientists the agency tapped to review the air pollution studies in the first place. Under the Clean Air Act, Congress requires the EPA to rely on advice from a Clean Air Scientific Advisory Committee (CASAC), which is made up of experts from a wide range of disciplines, drawn from industry and academia. CASAC head George Wolff, an atmospheric scientist with General Motors, says that of the 21 members of the panel, only four "bought into" the results of the studies on the health effects of PM 2.5. "All of the other members were influenced to varying degrees by the many uncertainties and unanswered questions that the studies have generated," he says.
As a result of doubts among several CASAC members, the council couldn't come to any conclusion as to what should be done about these so-called fine particles. In fact, only four members said the allowable level of PM 2.5 should be set as low as the EPA wanted it. The rest said the EPA should either set a less restrictive standard, or didn't answer the question at all.
For example, Roger McClellan, a toxicologist at the Chemical Industry Institute of Toxicology and a CASAC member, says that there is an "absence of solid data on PM 2.5." He thinks the EPA should "put in place a monitoring program...to get research quality data for obtaining the kind of epidemiological data we really need to make what is a multi-billion dollar decision."
According to some members of the CASAC panel, the EPA essentially ignored the doubts of its own science review board and plowed ahead with its new standards. …