San Francisco — This might not help Americans breathe any more freely, but it seems they are not entirely to blame for the chemical smog that hangs over cities along the U.S. West Coast. A new study indicates that about 10 percent of the ozone and other pollutants are arriving from the industrialized nations of East Asia.
“Although Los Angeles can’t blame the bulk of its air problems on Asia, there is definitely some contribution,” says Dan Jaffe, associate professor of science, technology and the environment at the University of Washington, Bothell. “Our results show that Asian pollution is affecting much of the U.S.West Coast, with Washington and Oregon affected slightly more because of wind patterns.”
Jaffe presented his findings at the fall meeting of the American Geophysical Union in San Francisco today (Wednesday, 8:30 a.m. PST). He is the principal investigator on a three-year project to measure pollutants in the atmosphere from the University of Washington’s remote Cheeka Peak research station on the Olympic Peninsula.
Previously Jaffe had proved that wind-borne Asian pollutants can reach as far as Hawaii. His first data from a West Coast site, acquired last May, measured atmospheric levels of pollutants such as nitrogen oxide, carbon monoxide, ozone and hydrocarbons. His collaborator, Terje Berntsen of the University of Oslo, Norway, used these data in a computer model that employs meteorological observations to predict and calculate where and how pollutants move through the atmosphere on any particular day. By combining industry’s known emissions of pollutants with such factors as wind speeds and direction, the computer program indicated that 10 percent of the ozone and carbon monoxide detected at Cheeka Peak had blown across the Pacific Ocean from Asia.
Ozone, which can damage the human respiratory system and destroy vegetation, is the product of nitrogen oxides released from the burning of fossil fuels, and has a long atmospheric life. Carbon monoxide is released directly into the atmosphere from the combustion of fossil fuels. Both, says Jaffe, are atmospheric pollutants that probably would have been considerably lower in Asia just 30 years ago.
Berntsen’s computer model is a simulation of the global atmosphere. It divides the Earth into 24 boxes of latitude and 36 of longitude, all piled nine layers high. In every box, at every moment of time, data on pollutants being released into the atmosphere is fed into the program, including the types of chemicals and their specific reactions. To this is added NASA wind data. In the Pacific, winds generally travel from west to east.
Because wind patterns can vary greatly over the course of a year, researchers typically record intense pollution levels on one day and much lower levels on the next. The computer “smoothes out” this difference by calculating the pollution level in each grid box, similar to taking a snapshot of the globe. To calculate how much of this global pollution originated in Asia, the researchers blank out the boxes over industrialized East Asia, and run the computer program a second time. They then look at the difference in the two simulations.
This is Jaffe’s fourth project investigating the transportation of pollutants through the atmosphere. He has also made measurements on Oki Island off the Coast of Japan and on Shemya at the tip of the Aleutian Islands chain.
All the data analyzed in the computer model, he says, indicates an increasing flow of pollutants from industrialized Asia. “Despite the recent economic problems, Asia is booming, and the spread of its pollutants is rapidly increasing,” he says.
Jaffe is at (425) 352-5357, or firstname.lastname@example.org
He can be reached through the AGU press room, (415) 905-1007
He is staying at the Juliana Hotel, (415) 392-2540