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May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

Hydrogen fluoride (as F)

CAS number: 7664–39–3

NIOSH REL: 3 ppm (2.5 mg/m3) TWA, 6 ppm (5 mg/m3) 15-minute CEILING

Current OSHA PEL: 3 ppm TWA

1989 OSHA PEL: 3 ppm TWA, 6 ppm STEL

1993-1994 ACGIH TLV: 3 ppm (2.6 mg/m3) CEILING

Description of Substance: Colorless gas or fuming liquid (below 67°F) with a strong, irritating odor.

LEL:. . Nonflammable Gas/Noncombustible Liquid

Original (SCP) IDLH: 30 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] that 24 mg/m3 (30 ppm) was tolerated by animals for a total of 41 hours without a fatality [Machle et al. 1934]. A concentration of 50 ppm is obviously too high to be selected as the IDLH, because Deichmann and Gerarde [1969] stated that 50 ppm may be fatal when inhaled for 30 to 60 minutes.

Existing short-term exposure guidelines: National Research Council (NRC) Emergency Exposure Limits (EELs) recommended to military and space agencies [Smyth 1966]

10-minute EEL: 20 ppm

30-minute EEL: 10 ppm

60-minute EEL: 8 ppm


Lethal concentration data:


SpeciesReferenceLC50 (ppm)LCLo (ppm)TimeAdjusted 0.5-hr LC (CF*)Derived value
RatDarmer et al. 1972 1,276-----1 hr1,799 ppm (1.41)180 ppm
MonkeyMacEwen & Vernot 1970 1,774-----1 hr2,501 ppm (1.41)250 ppm
RabbitTreon et al. 1950 -----3137 hr1,171 ppm (3.74)117 ppm
G. pigWohlslagel et al. 1976 4,327-----15 min3,072 ppm (0.71)307 ppm

*Note: Conversion factor (CF) was determined with "n" = 2.0 [ten Berge et al. 1986].

Other animal data: Guinea pigs and rabbits survived exposures to 30 ppm for 41 hours, but exposures to 300 ppm for 2 hours or more were fatal [Machle et al. 1934].

Human data:

It has been stated that 50 ppm may be fatal when inhaled for 30 to 60 minutes [Deichmann and Gerarde 1969]. Volunteers tolerated concentrations as high as 4.7 ppm for 6 hours per day for 10 to 50 days without severe adverse effects [Largent 1961].


Revised IDLH: 30 ppm [Unchanged]

Basis for revised IDLH: Based on acute inhalation toxicity data in humans [Deichmann and Gerarde 1969; Largent 1961] and animals [Machle et al. 1934], the original IDLH for hydrogen fluoride (30 ppm) is not being revised at this time.


1. Darmer KI Jr, Haun CC, MacEwen JD [1972]. The acute inhalation toxicology of chlorine pentafluoride. Am Ind Hyg Assoc J 33:661-668.

2. Deichmann WB, Gerarde HW [1969]. Hydrofluoric acid (hydrogen fluoride, HF). In: Toxicology of drugs and chemicals. New York, NY: Academic Press, Inc., pp. 317-318.

3. Largent EJ [1961]. Fluorosis. The health aspects of fluorine compounds. Columbus, OH: Ohio State University Press, pp. 34-39, 43-48.

4. MacEwen JD, Vernot EH [1970]. Toxic hazards research unit annual report: 1970. Wright-Patterson Air Force Base, OH: Aerospace Medical Research Laboratory, AMRL-TR-70-77.

5. Machle W, Thamann F, Kitzmiller K, Cholak J [1934]. The effects of the inhalation of hydrogen fluoride. I. The response following exposure to high concentrations. J Ind Hyg Toxicol 16(2):129-145.

6. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 842.

7. Smyth HF Jr [1966]. Military and space short-term inhalation standards. Arch Environ Health 12:488-490.

8. ten Berge WF, Zwart A, Appelman LM [1986]. Concentration-time mortality response relationship of irritant and systematically acting vapours and gases. J Haz Mat 13:301-309.

9. Treon JF, Dutra FR, Cappel J, Sigmon H, Younker W [1950]. Toxicity of sulfuric acid mist. AMA Arch Ind Hyg Occup Med 2:716-734.

10. Wohlslagel J, Dipasquale LC, Vernot EH [1976]. Toxicity of solid rocket motor exhaust: effects of Hcl, HF, and alumina on rodents. J Combustion Toxicol 3:61-70.

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