Huge Boreal Fires In 2004 Boosted Ozone Levels In Houston - ES&T

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Millions of acres of Alaskan and Canadian forests burned during the summer of 2004. That July, ozone pollution levels in Houston, Texas, skyrocketed. New research published September 26 in the Journal of Geophysical Research—Atmospheres connects the two distant events.

Measurements of optical depth of the air column above Houston on July 19 and 20, 2004, showed high aerosol levels, “some of the highest we saw all summer,” says Gary Morris of Valparaiso University. Morris and his co-workers traced the wind patterns for those days. The wind path led them back to eastern Alaska on July 12 and 13, when forest fires were pumping thick smoke into the air. Using satellite data, the team mapped carbon monoxide levels carried by winds from Alaska and Canada, down the Mississippi River to Dallas, Texas, and finally to Houston.

The large dose of ozone and its precursors from the fire plume magnified Houston’s air pollution. “A number of factors make Houston ripe for ozone production, static meteorology and local sources of both precursor nitrogen oxides and hydrocarbons,” says Morris. “The combination of the transported pollution from the forest fires and the local pollution led to a doubling of ozone levels in the first 5 kilometers” of the atmosphere.

“Ozone transports long distances,” something established even from local fires in Africa and elsewhere that send plumes much farther afield, sometimes across the Atlantic, says Paul Miller, deputy director of NESCAUM, a nonprofit association of air-quality agencies in the northeastern U.S. The new research “reinforces what we see here in the Northeast,” he adds, where the plume comes from fossil-fuel-burning power plants in the west.

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http://pubs.acs.org/subscribe/journals/esthag-w/2006/oct/science/nl_fires.html