Asian Air Pollution Recorded In U.S.

Monitor Wire Services

Two separate studies presented earlier this month at the American Geophysical Union conference recorded substances linked to burning, such as carbon monoxide, peroxyacetyl nitrate (PAN), and sulfur, could now be traced to Asia. In their aerosol form of tiny particles of liquids and solids, they can reflect a portion of the sun's radiation back into space. Sulfates also contribute to air pollution and acid rain.

Researchers Dan Jaffe and Theodore Anderson of University of Washington found that Asian pollution travels to North America in the troposphere, at a maximum altitude of about 10,000 feet, when meteorological conditions are just right. A low-pressure system over Alaska and a high-pressure cell near Hawaii can act like twin gears, pulling a high-speed conveyor belt laden with Asian air directly across the Pacific. The air usually reaches the West Coast in about seven days, but it can take as few as four.

In some instances, such as a major Gobi Desert dust storm earlier this year, pollution from Asia could have health implications on the West Coast. Still, on days of high air pollution levels in metropolitan areas such as San Francisco, Seattle and Los Angeles, the Asian factor is very small, Jaffe said.

"We're still talking about a relatively small part of the pollution, but with the rapid industrial growth taking place in Asia we expect that the impacts will increase," he explained.

As yet, the source of pollution is unknown. "In this suite of measurements, we don't yet have enough data to say it's coal burning in China or an oil source in Tokyo. But we're moving in that direction," Jaffe said.

A different study from the National Center for Atmospheric Research found more than half of all sulfur high over the Pacific Northwest comes from Asia. In contrast, most sulfates in Europe primarily come from European sources.

"It's widely recognized that sulfate aerosols are playing a major role in the climate system," says Jeffrey Kiehl, head of NCAR's Climate Modeling Section. Part of their goal is to learn more about natural and industrial sulfur high in the atmosphere, along with the interaction between sulfate aerosol particles and clouds, which have the ability to remove sulfates from the air.