SAN FRANCISCO -- Atmospheric pollution from eastern Asia is beginning to have measurable, though still small, effects on air quality in western North America, a researcher from the University of Washington, Bothell, said today. Pollutants traceable to Asia include carbon monoxide, a direct byproduct of combustion; peroxyacetyl nitrate (PAN), indirectly caused by combustion; and particulates, said Dan Jaffe, an associate professor who studies atmospheric chemistry and air pollution.
Jaffe, along with UW research meteorologist Theodore Anderson, UW atmospheric sciences research professor David Covert and several other researchers, are presenting their findings this week during the fall meeting of the American Geophysical Union. The research was discussed at a news conference today, and Jaffe also is coordinating panel presentations on the transportation of pollutants and dust across the Pacific and Atlantic oceans.
The scientists 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 the Aleutian Islands and a high-pressure cell near Hawaii, which remain stable and in place for at least several days, act like twin gears pulling a high-speed conveyor belt laden with Asian air directly across the Pacific Ocean. On average the air reaches the West Coast in about seven days, but it can take as few as four and as many as 10.
"What we know for sure is that we see pollutants coming from Asia under certain specific conditions," Jaffe said.
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.