Hydrofluoric Acid and Hydrogen Fluoride

Hazard Summary

Hydrofluoric acid (HF) and Hydrogen Fluoride (HF) are very corrosive, highly irritating and poisonous.  Hydrofluoric acid burns can be severe and extremely painful causing extensive damage to the skin and eyes, and to the mucous membranes as it is breathed in or swallowed.  Workers can die from injuries received in accidents with hydrofluoric acid or hydrogen fluoride.NFPA label for HF

Acute Health Effects

Hydrogen fluoride is an extremely corrosive chemical.  The vapor or liquid can cause severe corrosion of the skin, nose throat and eyes.  Accidental deaths have occurred from single inhalation and splash exposures.  Even weak liquid splashes or vapor exposures can cause severe, insidious and exceptionally painful chemical burns that may have a delayed appearance (see Table 1).

Skin Contact: Produces deep and extremely painful skin burns which take a long time to heal.  Burns from strong solutions are felt immediately but weaker solutions spilled on the skin may not cause pain for several hours (see Table 1).  Workers may have finished work and returned home before the pain hits them and they realize that something is wrong.  Fingernails not properly scrubbed can be a problem.

Even weak solutions of hydrofluoric acid will rapidly penetrate the skin, destroying the soft tissue and bone underneath.  For these reason a neutralizing agent (the calcium gluconate gel), which will also penetrate the skin, needs to be applied after the skin is washed.

Table 1: Time before onset of pain depends on concentration.
HF ConcentrationTime Before Onset of Pain
0 - 20% HF Up to 24 Hours
20 - 50% HF 1 - 8 Hours
50 - 70% HF < 1 Hour
> 70% HF Immediately


Eye Contact: Hydrofluoric acid fumes can dry out the eyes and cause a burning sensation, redness and secretions.  Splashing into the eyes may cause severe and irreversible damage that permanently affects the person's sight.

Inhalation: Fumes are corrosive and irritating to the respiratory tract and all mucosal tissue. Symptoms include lacrimation, cough, labored breathing, and excessive salivary and sputum formation. Excessive irritation causes chemical pneumonitis and pulmonary edema which could be fatal.

Other Long-Term Effects

Fluoride is deposited in the bone (fluorosis), and may cause pain and stiffness in joints and limbs.  There is no evidence that hydrogen fluoride exposure causes cancer.  There is inconclusive animal data about toxic effects to a fetus.

Before any HF Use

  1. All people who will be in the room while HF is in use must have completed training.  File a training documentation form signed by the trainee and by the supervisor noting the date, topics, and duration of the training. A hazard assessment must be completed as well.
  2. All first aid supplies must be acquired, labeled properly, dated, and assembled in the work area.
  3. The following information must be available and prominently posted in the work area:
    • The location of the HF first aid supplies
    • First aid and medical treatment instructions and material safety data sheets for all types of HF present (available as laminated poster from REM).
    • Standard operating procedure for HF use and the associated hazard assessment.

First Aid Supplies

  • Concentrated or anhydrous HF: In any work area where any quantity of HF in concentration ≥40% is to be used, the required first aid supplies are:
    • Benalkonium chloride 0.13% aqueous solution (BA(aq)),refrigerated, minimum two gallons
    • Basin, dishpan, or bowl for soaking body part
    • Gauze or towel soaks
    • Calcium gluconate, 2.5% in surgical lubricant or KY jelly
    • Calcium gluconate, 2.5% in sterile water, sterile container (for nebulizer)
    • Electric nebulizer
    • Two minute availability to ice cubes for soaking container and solution
    • Oxygen
  • Moderate Concentration HF: Where HF ≥ 5% but < 40% is used or stored in any quantity, the first aid requirements are as in A above with these changes:
    • BA(aq) only 1 gal minimum required
    • Nebulizer not required
    • Sterile water solution of calcium gluconate (for nebulizer) not required
    • Oxygen not required unless heating HF
  • Low Concentration HF: Where HF < 5% is used, the first aid supplies requirements are calcium gluconate, 2.5% surgical lubricant or KY jelly.

Personal Protective Equipment (PPE)

  • Lab Coat or acid-resistant clothing made with 0.4 kg (13 ounce) neoprene or polyvinyl chloride (PVC) with a nylon liner is recommended. 
  • The eyes should be protected from liquid splashes with goggles, safety glasses, or face shields, as appropriate.
  • Chemical resistant gloves 
  • Appropriate respiratory protection should be worn whenever vapor concentrations exceed permissible limits.

Good Work Practices

As an employee, you must take reasonable care to protect your own safety and the safety of others in your workplace.  When you are using hydrofluoric acid:

  • Follow your employer's instructions and training in the safe use of the material.
  • Use all of the protective equipment and clothing provided.
  • Tell your employer about any situation that may be dangerous so that something can be done before an accident happens.
  • Report any accidents, spills or leaks immediately.

Disposal and Storage

  • Do NOT store any Hydrofluoric acid in glass containers, use ONLY plastic (most manufacturers recommend less than two years).
  • Do NOT store any Hydrogen Fluoride cylinders for extended periods of time.
    • There is a potential over-pressure hazard with long term storage of carbon steel containers and Hydrogen Fluoride. Hydrogen Fluoride in the carbon steel container reacts very slowly with the iron in the steel to form iron fluoride and hydrogen which builds pressure within the container. Hydrogen Fluoride in carbon steel containers should not be stored for extended periods of time (recommend less than two years). Extreme caution should be taken during the handling of any carbon steel containers storing Hydrogen Fluoride that have been stored for extended periods of time.
    • If you suspect you have an old HF cylinder or lecture bottle, contact REM immediately at (765) 494-0121.
  • Submit a Hazardous Materials Pickup Request to REM to dispose of any unwanted Hydrofluoric Acid or Hydrogen Fluoride.