In this volume are assessed the risks to human health and the environment of Vanadium, a soft silvery-grey metal that can exist in a number of different oxidation states. The most common commercial form is vanadium pentoxide, and this exists in the pentavalent state as a yellow-red or green crystalline powder. It is mined in South Africa, Russia, and China, and is also produced by solvent extraction from uranium ores. About 90% of the approximately 64 000 tons of vanadium that are emitted to the atmosphere each year from both natural and anthropogenic sources comes from oil combustion. Irritation of eyes, nose, and throat, and wheeze and dyspnea are commonly reported in workers exposed to vanadium pentoxide dust and fume.