Scientists using NASA satellites and other data including computer models and ground sensors have demonstrated that pollutants traveling even thousands of miles can impact air quality.
The study concludes that ozone pollution levels increased significantly in the air above Houston on July 19 and 20, 2004. Researchers attribute this increase in part as a result of smoke transported into the area over the course of a week from forest fires raging in Alaska and Canada. The study is one of only a few that has quantitatively examined the impact of remotely generated pollutants on air quality in the lower atmosphere.
As part of a NASA-led field research project in the summer of 2004, researchers sampled a variety of trace gases and aerosols -- tiny particles suspended in the air -- across North America. During the time of the study, forest fires in western Canada and eastern Alaska were consuming more acres than at any time during the last 50 years. Meteorological conditions carried smoke from these intense fires eastward and southward to the U.S. Gulf Coast.
"The combination of our balloon-borne ozone data and observations by NASA satellites, aircraft, and a network of ground stations provided unprecedented insight into the origins of locally poor air quality in Houston on those two days," said study lead author Gary Morris of Valparaiso University, Valparaiso, Ind.
The researchers relied on imagery from NASA's Moderate Resolution Imaging Spectroradiometer on the Terra satellite, aerosol data from the Total Ozone Mapping Spectrometer satellite, and carbon monoxide data from the Atmospheric Infrared Sounder on the Aqua spacecraft to track the an air mass from the region of forest fires in western Canada and eastern Alaska on July 12-13, 2004. The air mass traveled across Canada, through the mid-western United States, and all the way to Houston, arriving there on July 19.