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A silent killer

Monday, May 26, 2008

postcard_final.jpgIn 2002, when EWG was first to report that state scientists estimated airborne dust and soot causes more deaths of Californians each year than AIDS, homicide and traffic accidents combined, the press, politicians and even some other environmental groups were skeptical. Surely that's too high, they said; you can't count every person whose life may be shortened a few months or years by breathing dirty air.

Six years later, reams of new evidence show that the estimate was indeed off. The actual number is three times higher. That means that airborne dust and soot – the kind of particulate pollution scientists call PM 2.5 – is responsible for the deaths of more than 24,000 Californians a year.

"Particle pollution is a silent killer," state Air Resources Board Chairwoman Mary Nichols said after reading the ARB staff's latest report.

There's a clear link between levels of the tiny particles – 2.5 microns or less, much thinner than a human hair – and cardiovascular deaths, Marla Cone reported in the LA Times.

The studies, including one by USC tracking 23,000 people in greater Los Angeles, and another by the American Cancer Society monitoring 300,000 people across the United States, have found rates of heart attacks, strokes and other serious disease increase exponentially after exposure to even slightly higher amounts of metal or dust. It is difficult to attribute individual deaths to particulate pollution, [said Bart Croes, chief researcher for the California Air Resources Board], but he said long-term studies that account for smoking, obesity and other risks have increasingly zeroed in on fine particulate pollution as a killer.

"There's no death certificate that says specifically someone died of air pollution, but cities with higher rates of air pollution have much greater rates of death from cardiovascular diseases," he said.

Californians exposed to high levels of fine particulates had their lives cut short on average by 10 years, the board staff found. Researchers also found that when particulates are cut even temporarily, death rates fall. "When Dublin imposed a coal ban, when Hong Kong imposed reductions in sulfur dioxide, when there was a steel mill strike in Utah . . . they saw immediate reductions in deaths," Croes said.

But there is good news, reported Jane Kay in the San Francisco Chronicle:

The drop in fine particulates statewide in the last decade, particularly in cities, has been 30 percent. One region that saw even greater improvement, the San Joaquin Valley, decreased 45 percent over the same time period due to new regulations, according to state air officials.

California already has the world's strictest standards for particulate pollution, although they're only non-binding goals. The same day the state's report was issued, the Air Resources Board met in Fresno and adopted a plan to push the San Joaquin Valley to meet those goals. But air quality activists are worried that the state's plan relies too much on voluntary reductions of diesel emissions by the trucking industry, and in light of the sharply higher death estimate they urged the state to go even further.

"Send this plan back to be strengthened or do it yourself," said Melissa Kelly-Ortega, program coordinator for the Merced-Mariposa Asthma Coalition. "You [ARB] will be saving lives."

That's no longer in dispute. The only question is how many lives the state is determined to save.

You can read the state's study here.