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Mercury (Vapor) (as Hg)

General Description

  • Synonyms: Quicksilver; Metallic mercury
  • OSHA IMIS Code Number: 1631 (IMIS Name History: Mercury, Inorganic [as Hg] prior to 9/1/89)
  • Chemical Abstracts Service (CAS) Registry Number: 7439-97-6
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: OV4550000 (metal)
  • Department of Transportation Regulation Number (49 CFR 172.101) and Emergency Response Guidebook: 2809 172 (metal)
  • NIOSH Pocket Guide to Chemical Hazards, Mercury Compounds [except (organo) alkyls] (as Hg): Physical description, chemical properties, potentially hazardous incompatibilities, and more
  • U.S. Environmental Protection Agency (EPA) Hazard Summary, Mercury: Uses, sources and potential exposure, acute and chronic health hazard information, and more

Exposure Limits and Health Effects

Exposure Limit Limit Values HE Codes Health Factors and Targets Organs

OSHA Permissible Exposure Limit (PEL) - General Industry

See 29 CFR 1910.1000 Table Z-2

(See also Z37.8-1971)

1 mg/10m3 Ceiling

HE3 Gingivitis, stomatitis
HE3 Kidney effects - proteinuria, nephritic syndrome
HE7 Erethism*
HE11 Mercurial pneumonitis
HE14 Dermatitis

OSHA PEL - Construction Industry

See 29 CFR 1926.55 Appendix A

0.1 mg/m3


HE3 Gingivitis, stomatitis
HE3 Kidney effects - proteinuria, nephritic syndrome
HE7 Erethism*
HE11 Mercurial pneumonitis
HE14 Dermatitis

OSHA PEL - Shipyard Employment

See 29 CFR 1915.1000 Table Z-Shipyards

0.1 mg/m3


HE3 Gingivitis, stomatitis
HE3 Kidney effects - proteinuria, nephritic syndrome
HE7 Erethism*
HE11 Mercurial pneumonitis
HE14 Dermatitis

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)

0.05 mg/m3 TWA


HE3 Gingivitis, stomatitis accompanied by excess salivation or a metallic taste
HE3 Kidney damage (nephritic edema, nephritic syndrome, renal failure)
HE7 Erethism* and micromercurialism**
HE10 Respiratory effects - pneumonitis, bronchitis, chest pains, dyspnea, coughing
HE14 Dermatitis, grayish-brown or yellow haze on hte lens of the eye

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV)

0.025 mg/m3

A4; Skin; BEI

HE3 Gingivitis, stomatitis, ocular and vision changes, hearing loss
HE3 Kidney effects
HE5 Teratogenic effects
HE7 Central nervous system changes resulting in tremors, emotional instability and irritability, peripheral neropathy

0.025 mg/m3 TWA

0.1 mg/m3 Ceiling

HE5 Reproductive effects

* Erethism is a central nervous system disorder characterized by irritability, weakness, sensitivity to stimulation, shyness, depression, insomnia, and eventually memory loss and tremors.

** Micromercurialism is a form of mercury poisoning caused by long-term exposure to low doses of mercury, resulting in erethism or a subclinical form of erethism.

  • National Toxicology Program (NTP) carcinogenic classification: Not listed
  • International Agency for Research on Cancer (IARC) carcinogenic classification: Group 3 (not classifiable as to its carcinogenicity to humans [mercury and inorganic mercury compounds])
  • EPA carcinogenic classification: Not classifiable as to human carcinogenicity
  • EPA Inhalation Reference Concentration (RfC): 3x10-4mg/m3
  • Agency for Toxic Substances and Disease Registry (ATSDR) Inhalation Minimal Risk Level (MRL): 0.0002 mg/m3 (chronic)
  • NIOSH Immediately Dangerous To Life or Health Concentration (IDLH): 10 mg Hg/m3
  • Notes:
    1. Exposure to mercury vapor may be a cause of Kawasaki disease (WHO/IPCS 1991).
    2. Several accounts of death have been reported following acute mercury vapor exposure, and they have all been attributed to respiratory failure (ATSDR 1999).
    3. Exposure to metallic mercury can result in decreased central auditory processing (Dutra et al. 2010).
    4. Insulin resistance increases with blood mercury level, and individuals with higher blood mercury levels are at an increased risk for insulin resistance (Chang et al. 2011).
    5. Color vision may be impaired following long-term exposure to mercury vapor (Feitosa-Santana et al. 2010).
    6. Mercury alters the immune system and may play a role in autoimmune diseases (Gardner et al. 2010).
    7. Exposure to mercury vapor has been shown to have a negative impact on the thymus gland, resulting in a significant reduction in thymulin hormone, possibly mediated through the nitric oxide pathway (Farahat et al. 2009).
    8. The EPA reference concentration is based on hand tremor, increases in memory disturbance; slight subjective and objective evidence of autonomic dysfunction observed in workers at 0.025 mg/m3 (EPA 1995).
  • Literature Basis:
    • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Mercury, all forms except alkyl. 2001.
    • ANSI: American National Standard Acceptable Concentrations of Inorganic Mercury and Non-Alkyl Organo Compounds. 1972.
    • ATSDR: Toxicological Profile for Mercury (PDF). 1999.
    • Chang, J.W., Chen, H.L., Su, H.J., Liao, P.C., Guo, H.R., Lee, C.C.: Simultaneous exposure of non-diabetics to high levels of dioxins and mercury increases their risk of insulin resistance. J Hazard Mat. 185(2-3):749-55, January 30, 2011.
    • Dutra, M.D., Monteiro, M.C., Camara, Vde.M.: Evaluation of central auditory processing in adolescents exposed to metallic mercury. Pro Fono. 22(3):339-44, July-September 2010.
    • EPA IRIS: Mercury, 1995.
    • Farahat, S.A., Rashed, L.A., Zawilla, N.H., Farouk, S.M.: Effect of occupational exposure to elemental mercury in the amalgam on thymulin hormone production among dental staff. Toxicol Ind Health. 25(3):159-67, April 2009.
    • Feitosa-Santana, C., Bimler D.L., Paramei, G.V., Oiwa, N.N., Barboni, M.T., Costa, M.F., Silveira, L.C., Ventura, D.F.: Color-space distortions following long-term occupational exposure to mercury vapor. Opthalmic Physiol Opt. 30(5):724-30, September 2010.
    • Gardner, R.M., Nyland J.F., Silva, I.A., de Souza, J.M., Silbergeld, E.K.: Mercury exposure, serum antinuclear/antinucleolar antibodies and serum cytokine levels in mining populations in Amazonian Brazil: A cross-sectional study. Environ Res. 110(4): 345-354, May 2010.
    • NIOSH/IPCS: International Chemical Safety Cards - Mercury. April 22, 2004.
    • NIOSH: Criteria for a Recommended Standard - Occupational Exposure to Inorganic Mercury. 1973.
    • NIOSH: Occupational Health Guideline for Inorganic Mercury. 1978.
    • WHO/IPCS: Environmental Health Criteria 118 - Inorganic Mercury. pp. 13-21, 68-83, 1991. Fawer, R.F., U. DeRibaupierre, M.P. Guillemin, M. Berode and M. Lobe. 1983. Measurement of hand tremor induced by industrial exposure to metallic mercury. J. Ind. Med. 40: 204-208.
    • Piikivi, L. and U. Tolonen. 1989. EEG findings in chlor-alkali workers subjected to low long term exposure to mercury vapor. Br. J. Ind. Med. 46: 370-375.
    • Piikivi, L. and H. Hanninen. 1989. Subjective symptoms and psychological performance of chlorine-alkali workers. Scand. J. Work Environ. Health. 15: 69-74.
    • Piikivi, L. 1989. Cardiovascular reflexes and low long-term exposure to mercury vapor. Int. Arch. Occup. Environ. Health. 61: 391-395.
    • Ngim, C.H., S.C. Foo, K.W. Boey and J. Jeyaratnam. 1992. Chronic neurobehavioral effects of elemental mercury in dentists. Br. J. Ind. Med. 49: 782-790.
    • Liang, Y-X., R-K. Sun, Y. Sun, Z-Q. Chen and L-H. Li. 1993. Psychological effects of low exposure to mercury vapor: Application of a computer-administered neurobehavioral evaluation system. Environ. Res. 60: 320-327.
  • Date Last Revised: 12/11/2012

Monitoring Methods used by OSHA

Laboratory Sampling/Analytical Method:
  • Hydrar or Hopcalite tube (200 mg) SKC brand with a prefilter/cassette
  • maximum volume: 96 Liters
  • minimum volume: 3 Liters
  • maximum flow rate: 0.2 L/min (TWA)
  • current analytical method: Atomic Absorption Spectroscopy; AAS/Cold vapor
  • method reference: OSHA Analytical Method (OSHA ID140)
  • method classification: Fully Validated
  • note: A prefilter, consisting of a mixed cellulose ester filter in a polystyrene cassette, is used with the active sampler. The prefilter assembly should be connected to the sampling tube with the minimum amount of Tygon tubing necessary. The filter of the sampler will be analyzed separately and reported as (Aryl and Inorganic) (as Hg) IMIS Code M111 based on the collection of particulate Mercury. The Hydrar or Hopcalite sorbent material will be analyzed and reported as Mercury (Vapor) (as Hg) IMIS Code 1631. These two results could then be combined to evaluate the transitional limit of TWA total Mercury, 1 mg/10m3, (Vapor and particulate).
On-Site Sampling Techniques/Methods:
  • Detector Tube
  • manufacturer: AUER/MSA
  • model/type: Hg-0.01, MSA P/N 497663, AUER P/N 5085-843
  • sampling information: follow manufacturer's instructions
  • upper measurement limit: 0.8 mg/m3
  • detection limit: approximately 0.005 mg/m3
  • overall uncertainty: unknown
  • method reference: on-site air secondary (manufacturer)
  • Detector Tube
  • manufacturer: Dräger
  • model/type: Mercury Vapour 0.1/b, order no. CH 23101
  • sampling information: 1 to 40 strokes
  • upper measurement limit: 2 mg/m3
  • detection limit: approximately 0.02 mg/m3
  • overall uncertainty: approximately 50%
  • method reference: on-site air secondary (manufacturer)
  • Detector Tube
  • manufacturer: Gastec
  • model/type: 40
  • sampling information: 0.5 to 5 strokes
  • upper measurement limit: 13.2 mg/m3
  • detection limit: 0.01 mg/m3
  • overall uncertainty: 16% for 0.25 to 2 mg/m3, 8% for 2 to 6 mg/m3
  • method reference: on-site air secondary (manufacturer)
  • Detector Tube
  • manufacturer: Matheson-Kitagawa
  • model/type: 8014-142S
  • sampling information: 1 or 5 strokes
  • upper measurement limit: 10 mg/m3
  • detection limit: approximately 0.05 mg/m3
  • overall uncertainty: unknown
  • method reference: on-site air secondary (manufacturer)

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