Recent WUI fires include the 2002 Hayman Fire, the 2000 Los Alamos Fire and the 1991 Oakland Hills Fire. The devastation caused by these fires is massive; the Hayman Fire in Colorado burned 137,000 acres and destroyed over 600 structures. As a consequence, fires in the WUI can have a devastating effect on human life, property loss, and local economies. Embers or firebrands are produced as trees and other objects burn in these fires. These firebrands are entrained in the atmosphere and may be carried by winds over long distances. Hot firebrands ultimately come to rest and may ignite surfaces far removed from the fire, resulting in fire spread.
Due to the sheer complexity involved, it is useful to delineate the firebrand problem into three main areas: the generation from vegetation and structures, subsequent transport through the atmosphere, and the ultimate ignition of fuels after firebrand impingement. Of these processes, firebrand transport has been investigated most extensively. Models have generally assumed firebrand sizes to perform transport calculations, since little quantitative data exists with regard to firebrand size or firebrand mass produced from vegetation and structures. The general lack of knowledge of the type of firebrands that are produced as well as the type of materials that may be ignited has greatly hampered further understanding of this problem. Experimental research opportunities exist to investigate firebrand generation from vegetation and probe ignition of fuel beds due to contact by firebrands.