And the rapidly changing climate in northern latitudes makes it likely such fires will have increasingly serious ramifications for air quality all along the West Coast of North America, said Dan Jaffe, an environmental scientist at the University of Washington, Bothell.
"In the past, we haven't considered that long-range transport can bring in pollution levels that are significant," Jaffe said. "What we're finding is that these events can bring in significant levels of pollution, even to urban areas where the levels already are relatively high."
In the spring and summer of 2003, Siberian forest fires consumed 46.7 million acres, or nearly 73,000 square miles an area slightly larger than the state of Washington. That was more than twice the annual average from 1996 until 2003. The fires burned most intensely during May and June, and the smoke plume was tracked by satellites and detected during a research flight off the Washington coast on June 2.
Between May 27 and June 9, air quality monitors in British Columbia and Washington detected levels of ozone that were higher than average for that period. Previous daily data had been gathered from May through September in 1996 through 2003. Ozone readings during that time varied according to temperature, but generally ranged from a low of a few parts per billion by volume to around 80 parts per billion. Between June 1 and June 6, the monitor sites recorded ozone nine to 17 parts per billion by volume higher than normal, and the surface monitoring suggested a continual influence from the Siberian fires, as did the June 2 research flight.
On June 6, the ozone-monitoring site at Enumclaw, Wash., about 30 miles southeast of Seattle, registered an eight-hour average of 96 parts per billion by volume. The U.S. Environment
Contact: Vince Stricherz
University of Washington