The manual summarizes technical information that will assist in identifying and controlling hydrogen fluoride release hazards specific to the South Coast Air Quality Management District (SCAQMD) of southern California. The SCAQMD has considered a strategy for reducing the risk of a major accidental air release of toxic chemicals. The strategy includes monitoring the storage, handling, and use of certain chemicals and provides guidance to industry and communities. Anhydrous hydrogen fluoride, a corrosive liquid that boils at room temperature, rapidly absorbs moisture to form highly corrosive hydrofluoric acid. Hydrogen fluoride gas has an IDLH (immediately dangerous to life and health) concentration of 20 ppm, which makes it a substantial acute toxic hazard. Reducing the risk associated with an accidental release of hydrogen fluoride involves identifying some of the potential causes of accidental releases that apply to the processes that use hydrogen fluoride in the SCAQMD. The manual identifies examples of potential causes as well as measures that may be taken to reduce the accidental release risk.