Oxygen deficiency hazard in a storage tank

Oxygen Deficiency Hazard (ODH) occurs when the indoor oxygen (O2) content drops to a level that may expose workers to the risk of asphyxiation. ODH is different from traditional chemical air contamination scenarios and typical inhalation exposures because of the following peculiarities that are described throughout the chapter: • There is no consensus on a unique safe exposure limit for the O2 content that can be used for judging the acceptability of exposures. • The O2 reduction and/or depletion can be created by other substances potentially present and/or released in the working environment, which are responsible for the displacement of the O2 available in the air.