Agent Name
Hydrogen chloride
Alternative Name
Hydrochloric acid
Major Category
Toxic Gases & Vapors
Synonyms
Hydrochloric acid; Muriatic acid; [NIOSH]; Anhydrous hydrogen chloride; Anhydrous hydrochloric acid; HCl; Hydrochloride; [CHEMINFO] UN1050; UN1789; UN2186
Category
Acids, Inorganic
Description
Colorless to slightly yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.] [NIOSH]
Sources/Uses
Sold as muriatic acid for a variety of household and construction purposes, e.g., scale remover; used to clean, pickle, and electroplate metal; also used in oil well activation, ore reduction, leather tanning, swimming pool cleaning, and refining of edible oils; [ACGIH] Used as a wet etchant in semiconductor manufacturing at a standard concentration of 36%; [CSH, p. 46]
Comments
Liquid causes second degree burns after contact for a few minutes; [CHRIS] Hydrogen chloride is highly corrosive; Muriatic acid (37% HCl) is highly corrosive; HCl solution < 30% is corrosive; [Quick CPC] Listed as one of "major irritant airborne toxicants"; [LaDou, p. 563] Possible frostbite from contact with liquid; [NIOSH] The following chemicals can release HCl when spilled in water: Acetyl chloride, Boron trichloride, Chloroacetyl chloride, Chromyl chloride, Dichloroacetyl chloride, Phosphorus trichloride, Phosphorus pentachloride, Phosphorus oxychloride, Titanium tetrachloride, Aluminum chloride, Chlorosulfonic acid, Silicon tetrachloride, CHLOROSILANES, Surfuryl chloride, Thionyl chloride, and metal alkyl and aryl halides. [ERG 2016] See the Process, "Toxic Gas from Spilling Chemical in Water." Hydrogen chloride is fibrogenic to the lungs in the context of an acute inhalation exposure complicated by bronchiolitis obliterans.
Skin Designation (ACGIH)
No
PEL (OSHA)
Ceiling(OSHA) = 5 ppm
Excerpts from Documentation for IDLHs
Other human data: It has been reported that 50 to 100 ppm for 1 hour is barely tolerable and that 35 ppm causes irritation of the throat [Henderson and Haggard 1943]. It has also been reported that work is impossible at 50 to 100 ppm but is difficult but possible at 10 to 50 ppm [Flury and Zernik 1931].
Odor Threshold Low
0.25 ppm
Odor Threshold High
10.06 ppm
Lethal Concentration
LC50 (rat) = 3,124 ppm/1 hr
Explanatory Notes
Odor threshold from AIHA; The Guide from the Emergency Response Guidebook is for "Hydrogen chloride, anhydrous."
IARC Carcinogen
Not classifiable
ACGIH Carcinogen
Not Classifiable
Diseases
Occupational diseases associated with exposure to this agent:
Processes
Industrial Processes with risk of exposure:
Activities
Activities with risk of exposure: