Powered by GoogleTranslate

Hydrazoic Acid

General Description

  • Synonyms: Azoimide; Diazoimide; Hydrogen Azide; Hydronitric acid; Hydrozoic Acid (Var.); Triazoic Acid; stickstoffwasserstoffsaeure
  • OSHA IMIS Code Number: 2243
  • IMIS Name History: Sodium Azide prior to 9/1/89; Sodium Azide (as HN3) from 9/1/89 to 8/25/04
  • Chemical Abstracts Service (CAS) Registry Number: 7782-79-8
  • Chemical Description and Physical Properties:
    • liquid
    • molecular weight: 43.03
    • molecular formula: HN3
    • boiling point: 37°C
    • melting point: -80°C

Exposure Limits

  • American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 0.11 ppm Ceiling; Appendix A4 - Not Classifiable as a Human Carcinogen (TLV listed under Sodium azide as Hydrazoic acid vapor)
  • National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 0.1 ppm Ceiling; Skin; (REL listed under Sodium Azide (as HN3))

Health Factors

Potential Symptoms: Irritation of eyes, skin, respiratory tract; headache, dizziness, nausea, vomiting, diarrhea; lassitude (weakness, exhaustion); blurred (or temporary loss of) vision; low blood pressure, collapse; palpitation, tachycardia; kidney changes (decreased plasma creatinine); nasal stuffiness; cough, shortness of breath; chills, fever; AT DOSES >10 mg/kg: Convulsions, coma, pulmonary edema, flaccidity, severe hypotension (shock) , metabolic acidosis, arrhythmia, bradycardia, asystole

Health Effects: Acute CNS and blood pressure effects (HE4); Irritation-Eyes, Nose, Throat, Skin---Moderate (HE15); Mutagen (HE2); Explosive (HE18)

Affected Organs: Eyes, skin, CNS, cardiovascular system, kidneys


  1. Hydrazoic acid is formed from dry sodium azide when it contacts water. Its formation is favored in acidic solutions. OSHA does not have a PEL for either chemical.
  2. NIOSH does not have an IDLH level for hydrazoic acid. The LC50 (inhalation, mouse) is 34 mg/m3 of air and the LD50 (oral, rat) is 33 mg/kg of body weight.
  3. The CDC has received no reports of sodium azide exposure following automobile airbag deployment, but cautions that the stomach contents of a person who has ingested sodium azide and is vomiting may be producing a toxic gas, i.e., hydrazoic acid.
  4. Red blood cells, perhaps via the enzyme catalase, can convert azide to nitric oxide, a potent vasodilator.

Literature Basis:

  • CDC Emergency Preparedness & Response: Facts About Sodium Azide.
  • Fisher Scientific UK: Material Safety Data Sheet: Sodium Azide.
  • NIOSH Pocket Guide to Chemical Hazards: Sodium azide.
  • International Chemical Safety Cards (WHO/IPCS/ILO): Sodium azide.
  • Chang, S. and Lamm, S.H.: Human health effects of sodium azide exposure: a literature review and analysis. Int. J. Toxicol. 22(3): 175-186, 2003.
  • Miljours, S. and Braun, C.M.J.: A neuropsychotoxicological assessment of workers in a sodium azide production plant. Int. Arch. Occup. Environ. Health 76(3): 225-232, 2003.
  • Pohanish, R.P. (editor): Hydrazoic Acid. Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 1. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1269-1270.
  • Shahidullah, M., et al.: Role of catalase in the smooth muscle relaxant actions of sodium azide and cyanamide. Eur. J. Pharmacol. 435(1): 93-101, 2002.
  • Trout, D., Esswein, E.J., Hales, T., Brown, K., Solomon, G. and Miller, M.: Exposures and health effects: an evaluation of workers at a sodium azide production plant. Am. J. Ind. Med. 30(3): 343-350, 1996.
  • Weiss, J.S.: Reactive airway dysfunction syndrome due to sodium azide inhalation. Int. Arch. Occup. Environ. Health 68(6): 469-471, 1996.

Date Last Revised: 08/02/2004

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):
  • 37 mm PVC filter and Coated Silica Gel Tube connected in series
  • minimum time: 5 Minutes
  • maximum flow rate: 1.0 L/min (Ceiling)
  • current analytical method: Ion Chromatography; IC/UV
  • method reference: OSHA Analytical Method (OSHA ID-211)
  • method classification: Fully Validated
  • note: The silica gel is coated with a reactive substrate. After collection submit samples to the laboratory using normal shipping procedures as soon as possible. At the lab, refrigerate samples until analysis.
  • note: The TLV-Ceiling for sodium azide is 0.29 mg/m3 measured as sodium azide, and it is 0.11 ppm measured as hydrazoic acid vapor. The basis for this dual TLV is that sodium azide has high solubility in water and will form hydrazoic acid in water, that hydrazoic acid vapor is present where sodium azide is handled, and that sodium azide is used to produce hydrazoic acid. The same sampling method (OSHA ID-211) is used for both substances and it is possible that both chemicals will be present in the same sample. The analytical method cannot differentiate between the two chemicals, and the section of the sampler where the substance is found serves as the basis for identification of the chemical substance. Analytical results are usually expressed as sodium azide. It is essential that analytical results be expressed as only one of the two chemical substances so that sample results can be compared to the appropriate TLV-Ceiling.

** All Trademarks are the property of their respective owners.

Back to Top

Thank You for Visiting Our Website

You are exiting the Department of Labor's Web server.

The Department of Labor does not endorse, takes no responsibility for, and exercises no control over the linked organization or its views, or contents, nor does it vouch for the accuracy or accessibility of the information contained on the destination server. The Department of Labor also cannot authorize the use of copyrighted materials contained in linked Web sites. Users must request such authorization from the sponsor of the linked Web site. Thank you for visiting our site. Please click the button below to continue.