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Nitrous oxide

General Description

  • Synonyms: Dinitrogen monoxide; Hyponitrous acid anhydride; Laughing gas; Nitrogen oxide
  • OSHA IMIS Code Number: 1953
  • Chemical Abstracts Service (CAS) Registry Number: 10024-97-2
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: QX1350000
  • Department of Transportation Regulation Number (49 CFR 172.101) and Emergency Response Guidebook: 1070 122; 2201 122 (refrigerated liquid)
  • NIOSH Pocket Guide to Chemical Hazards, Nitrous oxide: chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

  • OSHA Permissible Exposure Limit (PEL):
    • Construction Industry: 29 CFR 1926.55 Appendix A -- Simple asphyxiants. The limiting factor is the available oxygen which shall be at least 19.5% and be within the requirements addressing explosion in part 1926.
    • Maritime: 29 CFR 1915.1000 Table Z-Shipyards -- Simple asphyxiants. The limiting factor is the available oxygen which shall be at least 18 percent and be within the requirements addressing explosion in subpart B of part 1915.
  • American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 50 ppm, 90 mg/m3 TWA; Appendix A4 - Not Classifiable as a Human Carcinogen
  • National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 25 ppm, 46 mg/m3 TWA over the time exposed. [Note: REL for exposure to waste anesthetic gas.]

Health Factors

  • Carcinogenic Classification:
  • Potential Symptoms: Dyspnea; euphoria, drowsiness; headache; asphyxia; reproductive effects; frostbite (from contact with liquid), lowering of consciousness.
  • Health Effects: Reproductive Hazard (Male and Female) (HE5); CNS effects (HE7); Asphyxiant (HE17); Bone marrow depression (HE12).
  • Affected Organs: Respiratory system, CNS, peripheral nervous system, reproductive system
  • Notes:
    1. OSHA does not have a PEL for nitrous oxide. [See also Waste Anesthetic Gases.]
    2. Occupational exposure to nitrous oxide is primarily via its use in anesthesia and analgesia by health care personnel.
    3. Nitrous oxide is a drug of abuse by inhalation and has caused a number of deaths from asphyxia.
    4. Long-term exposure to nitrous oxide can result in some symptoms of pernicious anemia: megaloblastic bone-marrow depression or peripheral and central neuropathy (tingling, numbness, impairment of equilibrium, difficulty in thinking clearly).
    5. These symptoms result from the inhibition of methionine synthase by the nitrous oxide-induced inactivation of the reduced form of vitamin B12.
  • Literature Basis:
    • NIOSH Pocket Guide to Chemical Hazards: Nitrous oxide.
    • International Chemical Safety Cards (WHO/IPCS/ILO): Nitrous oxide.
    • Pohanish, R.P. (editor): Nitrous Oxide. In, Sittig’s Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 2. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1748-1749.
    • Rowland, A.S., Baird, D.D., Shore, D.L., Weinberg, C.R., Savitz, D.A. and Wilcox, A.J.: Nitrous oxide and spontaneous abortion in female dental assistants. Am. J. Epidemiol. 141(6): 531-538, 1995.
    • Suruda, A.J. and McGlothlin, J.D.: Fatal abuse of nitrous oxide in the workplace. J. Occup. Med. 32(8): 682-684, 1990.
    • Weimann, J.: Toxicity of nitrous oxide. Best Pract. Res. Clin. Anaesthesiol. 17(1): 47-61, 2003.
  • Date Last Revised: 05/30/2007

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):
  • VAPOR-TRAK Nitrous Oxide Monitor
  • maximum time: 16 Hours
  • minimum time: 15 Minutes
  • current analytical method: Infrared; IL33
  • method reference: Follow Manufacturer's Instruction Sheet. The Salt Lake Technical Center has not evaluated this product.
  • method classification: Not Validated
  • note: Analysis performed by manufacturer of badge. Badges are sent to the OSHA Technical Center. The Salt Lake Technical Center has not evaluated this product. CSHO's should consult OSHA instruction CPL 2-2.60 prior to taking any samples where exposure to bloodborne pathogens could occur.
  • Five Layer Aluminized Gas Sampling Bag (5 liter)
  • maximum volume: 5 Liters
  • maximum flow rate: 0.05 L/min
  • current analytical method: Infrared; IL52
  • method reference: OSHA In-House File
  • method classification: Not Validated
Laboratory Sampling/Analytical Method (Wisconsin OHL):
  • sampling media: Evacuated Cans - Back Filled with Nitrogen (Hold button down for a full 10 seconds)
  • maximum volume: 120 mLiters
  • current analytical method: Mass Spectrometry; GC/MS
  • method reference: (WOHL In-House File)
  • method classification: Not Validated
  • note: Call WOHL for instructions and evacuated cans

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