Coke dust is a fine powder that is produced during the processing of coke, a fuel with few impurities and a high carbon content, usually made from coal. Coke is used as a fuel and as a reducing agent in smelting iron ore in a blast furnace. Coke dust is combustible and can form dust clouds of finely divided, combustible material, which can be an explosion hazard. It is also a source of fine dust that can penetrate the filtering process of the human airway, lodge in the lungs, and cause serious health problems. Coke dust can be produced during the coking of coal, which is the process of driving off smoke-producing constituents from coal. It can also be produced during the handling and storage of petroleum coke, which is a residue high in carbon content and low in hydrogen that is the final product of thermal decomposition in the condensation process in cracking. Coke dust can be found near the origin of an explosion or in a room or wide place where the velocity of the explosion is low and there is insufficient oxygen for complete combustion of the coal dust.