A refuse dump near Naco, Sonora, Mexico, caught fire and burned from December 1 to December 5, 2001. The fire, which consumed large quantities of household refuse, also generated a large quantity of smoke. During this period, considerable smoke was intermittently present in Naco, Arizona. This report summarizes the events that occurred during the fire and analyzes the data collected by the Arizona Department of Health Services and the Arizona Department of Environmental Quality to determine the extent of the public health threat from the fire.