When factories, power plants or automobiles spew pollutants into the air, these emissions take to the wind and travel wherever it blows. A toxic blend of soot, ash, acids and other airborne particles crosses borders and oceans—polluting faraway places and affecting climate, rainfall and causing acid rain.
An international consortium of researchers from three different projects are investigating one of the world's most potent sources of air pollution: the so-called "Asian Express," created over the last decade by rapid Asian industrialization, which is driving changes in the Earth's atmosphere.
A series of recent studies tracked the brown pollution cloud along its annual transpacific migration. Each spring, strong winds blow east from Central China, gathering dust which acts like a sponge, soaking up pollution from East Asia's thick blanket of smog.
Traveling Particulate Stew
This dirty particulate stew most directly threatens Japan, Korea and Taiwan. But this brown cloud can blow eastward across 6,000 miles of ocean to the United States in only four to 10 days—too little time for the air to be cleansed over the sea.
Given the pass-along nature of pollution, however, researchers point out that every region of the world makes its contribution.
"The amount of pollution we get from Asia is probably not dramatically different from what we send to Europe, and Europe sends to Asia," says Barry Joe Huebert, an atmospheric chemist at the University of Hawaii in Honolulu. "We have to think of atmosphere chemistry and its impact on air quality and climate as global issues."
Huebert and other authorities on wind borne pollution presented their findings in December at the annual meeting of American Geophysical Union. Their research identified the major sources of pollution and quantified how much reaches North America.
"The ultimate use of this data will be for setting policy for the use of fossil fuels and other pollutants we put into the atmosphere," said Huebert.
During spring 2001 and 2002, hundreds of scientists from 13 countries joined forces to study air pollution from Asia. The international team tracked and sampled dust plumes from ground stations, aircraft, ships and by satellite.
Atmospheric Aerosols
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