Why is hydrofluoric acid so dangerous? there are about 3 damages: (1) hydrofluoric acid has two mechanisms that cause tissue damage, corrosive burns from free hydrogen ions and chemical burns from tissue penetration of the fluoride ion. (2) Fluoride ions penetrate and form insoluble salts with calcium and magnesium. (3) Soluble salts are also formed with other cations but dissociate rapidly. Consequently, fluoride ions release, and further tissue destruction occurs.

Fire and explosion hazard: Hydrogen fluoride is non-combustible, but may create irritating and corrosive fumes of fluorides when heated or in combination with steam or water. Since hydrogen fluoride does not burn, use an extinguishing agent suitable for surrounding fire. Use water to absorb fumes and keep containers cool. Heat released when water or steam combines with hydrogen fluoride or hydrofluoric acid could be hazardous. For fires involving hydrofluoric acid, apply water in flooding quantities. Hydrofluoric acid and various metals may form hydrogen (extremely flammable gas) creating a fire hazard.Symptoms of hydrofluoric acid burns:The Hydrogen Fluoride molecule is so mobile that it may easily pass through the skin. Because Fluorine has an extremely high affinity for Calcium, bones will be attacked, and this may result in hypocalcaemia. There may be no pain immediately after the burn, leading the injured person to believe that they are not indanger. 

Concentrations less than 20% - Erythema (skin redness) and pain may be delayed up to 24 hours, often not reported until tissue damage is extreme. In one study, 7% hydrofluoric acid produced symptoms in 1 to several hours, 12%hydrofluoric acid in less than one hour, and 14.5% hydrofluoric acid immediately. Concentrations 20 to 50% - Erythema and pain may be delayed from 1 to 8 hours, and is often not reported until tissue damage is extreme. Concentratins greater than  50% - Produces immediate burning, erythema, and tissue damage.

Hydrofluoric acid accidents: 1981 – At the Sullivan Park Research Facility of Corning, Inc., an hydrofluoric acid tank leaked. A clean-up crew went in without proper respirators and 2 workers died. 1994 – A lab tech in Western Australia died from burns sustained when he accidentally spilled concentrated (70%) hydrofluoric acid on himself. 1996 – A NYC sanitation worker died of toxic fumes released when hydrofluoric acid blew up in the back of his truck.