WASHINGTON — From 500 miles in space, satellites track brown clouds of dust, soot and other toxic pollutants from China and elsewhere in Asia as they stream across the Pacific and take dead aim at the western U.S.
A fleet of tiny, specially equipped unmanned aerial vehicles, launched from an island in the East China Sea 700 or so miles downwind of Beijing, are flying through the projected paths of the pollution taking chemical samples and recording temperatures, humidity levels and sunlight intensity in the clouds of smog.
On the summit of 9,000-foot Mt. Bachelor in central Oregon and near sea level at Cheeka Peak on Washington state's Olympic Peninsula, monitors track the pollution as it arrives in America.
By some estimates more than 10 billion pounds of airborne pollutants from Asia — ranging from soot to mercury to carbon dioxide to ozone — reach the U.S. annually. The problem is only expected to worsen: Some Chinese officials have warned that pollution in their country could quadruple in the next 15 years.
While some scientists are less certain, others say the Asian pollution could destabilize weather patterns across the North Pacific, mask the effects of global warming, reduce rainfall in the American West and compromise efforts to meet air-pollution standards.
"East Asia pollution aerosols could impose far reaching environmental impacts at continental, hemispheric and global scales because of long-range transport," according to a report earlier this year in the Journal of Geophysical Research. The report said that a "warm conveyor belt" lifts the pollutants into the upper troposphere — the lowest layer of Earth's atmosphere — over Asia, where winds can bring it to the U.S. in a week or less.
The National Academies of Science, at the request of the Environmental Protection Agency, NASA, the National Oceanic and Atmospheric Administration and in consultation with the State Department, has assembled a panel to examine the problem and its impact. Its report is due next summer.
"Everyone realizes this is an issue of growing importance," said Laurie Geller of the National Academies of Science. "This is very challenging science with lots of complexities and a lot of uncertainties."
Though the problem of Asian air pollution has been known for years, no one has a handle on how much is blown in and what it includes. Scientists say Washington state and Oregon might be feeling the brunt of the effects.
"This pollution is distributed on average equally from northern California to British Columbia," said Dan Jaffe, a professor of environmental science at the University of Washington's Bothell campus. "Anyone who has gone out to measure it has found something."
Particulates such as dust and soot, along with heavy metals, pesticides, PCBs, mercury, ozone, carbon dioxide, nitrogen dioxide and sulfur dioxide have all been found. Jaffe said the pollutants can't be tracked to a single source such as a particular coal-burning plant, but their "chemical fingerprints" can point to a specific country.
Viruses, bacteria and fungi also can be transported on dust particles, though, so far, they've been found only on the dust and sand blowing off African deserts, not Asian ones.
Mercury, one of the most hazardous pollutants from the hundreds of coal-burning electricity generating plants in China and elsewhere in Asia, is of particular concern. One study estimated a fifth of the mercury entering Oregon's Willamette River comes from overseas, with China as the mostly likely source.
Jaffe, a member of the National Academies of Science panel studying the issue, is wary of such reports. But he still estimates that as much as 30 percent of the mercury deposited in the U.S. from airborne sources comes from Asia, with the highest concentrations in Alaska and other western states.
"Ten years ago, there was a lot of skepticism," Jaffe said. "People assumed the atmosphere scrubbed itself and didn't believe these pollutants could travel thousands of miles."
The pollution from Asia will only make it increasingly difficult for the U.S. to meet stricter and stricter air quality standards, said Lyatt Jaegle, a professor of atmospheric sciences at the University of Washington in Seattle.
"It is only expected to get worse," Jaegle said of the Asian air pollution reaching the U.S. She added that scientists have discovered the problem isn't unique to the Pacific Rim. "Air pollution is not a local or regional problem, it is a global problem."
Days after a major dust storm in the Gobi Desert in Asia, visibility in the Grand Canyon was obscured. Dust from deserts in North Africa has reached Florida. U.S. air pollution can reach across the Atlantic to Europe, even as pollution from Europe can circle the globe and reach the U.S.
Air can circulate around the world in three weeks or less. The National Academies of Science is not limiting itself to pollution from Asia and will study the phenomenon worldwide.
"It's one atmosphere," said Mark Schoeberl, project scientist for NASA Aura satellite program.
Schoeberl said his and other satellites have "transformed" what scientists know about the Earth and can provide a near real-time snapshot of the track of airborne pollution. When the price of gasoline spikes, Jaffe said satellites can detect an increase in sulfur dioxide levels at Saudi Arabian refineries. They've also helped confirm global dimming as sunlight reaching the planet's surface is decreasing because the airborne pollution reflects it back to space. In some places, like Israel, sunlight has decreased 10 percent, Jaffe said.
The pollution also can mask the effect of global warming by reflecting the sunlight, said Veerabhadran Ramanathan, a climate researcher at the Scripps Institution of Oceanography in California who's heading the team of scientists flying the unmanned aerial vehicles off Korea this summer.
The UAVs started flying as China shut down factories and banned automobiles from Beijing during the Summer Olympics and are still flying as pollution levels increase.
"It's a once in a lifetime opportunity," Ramanathan said.
The reduction in sunlight could be increasing rainfall or it might be decreasing rainfall because of less evaporation off the ocean, Ramanathan said. In addition, the soot falling on mountains in the western U.S. could increase snowmelt, he said.
"There are a lot of questions and few answers," Ramanathan said. "We shouldn't be pointing fingers. Everyone else is some one else's backyard. This is a global problem."
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