The rapid combustion of a dispersion of combustible airborne dust particles within a confined space. Dust can arise from many processes and include materials such as coal, flour, metals, custard powder, and sawdust, and form an explosive suspension in air (oxygen). Within the confined space, the dispersion of particles collectively have a very high surface area to volume ratio. Typical ignition sources include open flames, electrical static discharge, or arcing in process equipment, hot surfaces, and friction.