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December 06, 2000


Home > chemicals > Ammonia

Ammonia (Anhydrous) Chemical Backgrounder


Ammonia (CAS# 7664-41-7) is a colorless gas with a pungent, suffocating odor. It is used as a refrigerant, a cleaning and bleaching agent, and a household cleaner. It is used to produce fertilizers, plastics, explosives, and pharmaceuticals, and to control fungal growth on grapefruit, lemons, and oranges. It is also used as a preharvest cotton defoliant, and in metal treating operations such as nitriding, carbo-nitriding, bright annealing, furnace brazing, sintering, sodium hydride descaling, and atomic hydrogen welding. It is used as a chemical intermediate for urea, ammonium nitrate, ammonium salts, adipic acid for nylon, hexamethylenediamine for nylon, acrylonitrile for fibers and plastics, caprolactam for nylon, isocyanates for plastics, and hydrazine. It is used as a catalyst in phenol-formaldehyde condensation and in urea-formaldehyde condensation to make synthetic resin.

Dissociated ammonia is used as a convenient source of hydrogen for the hydrogenation of fats and oils. The petroleum industry uses anhydrous ammonia to neutralize the acid constituents of crude oil and to protect equipment such as bubble plate towers, heat exchangers, condensers, and storage tanks from corrosion. It is used in the rubber industry for stabilization of raw latex to prevent coagulation during transportation and storage.

Ammonia may be added to water before (preammoniation) or after (postammoniation) addition of chlorine. Preammoniation can prevent formation of tastes and odors that are caused by reaction of chlorine with phenols and other substances. Postammoniation is the most often used ammonia-chlorine water treatment process.

Chemical properties:

Ammonia is alkaline and caustic, and is a powerful irritant. It is incompatible or reactive with strong oxidizers, acids, halogens, salts of silver, and zinc. It is corrosive to copper and galvanized surfaces; liquid ammonia will attack some forms of plastics, rubber, and coatings. It is highly water-soluble and soluble in chloroform and ether. It is easily liquefied under pressure.

Synonyms for ammonia are anhydrous ammonia, ammonium hydroxide, aqua ammonia, ammonia gas, ammonia water, and aqueous ammonia.


Health effects:

Exposure to ammonia can cause lacrimation, burning sensation, swelling of larynx, spasm of glottis, asphyxia, conjunctivitis, laryngitis, severe pulmonary and gastrointestinal irritation, nausea, vomiting, diarrhea, abdominal pains, pulmonary edema, dyspnea, bronchospasm, chest pain, vesiculation, wheezing, cold and clammy skin, convulsions, collapse, coma, and even death from acute laryngeal edema. Milder exposure may predispose to bronchopneumonia following a chemical pneumonitis.

Because is it highly water-soluble, ammonia can cause extensive damage to mucous membranes of the eyes, nose, oropharynx, larynx, and tracheobronchial tree. When ingested, ammonia can cause corrosive esophagitis, sometimes with an associated gastritis. Inhaling ammonia can cause secretion of saliva and retention of urine. Inhaling anhydrous ammonia gas can produce acute, chronic respiratory disease; diffuse tracheobronchitis with severe bronchoconstruction; and bronchorrhea.

Anhydrous liquid ammonia produces second-degree burns on the skin and extensive destruction of the anterior chamber in the eye. If extensive, these lesions can cause edema and sloughing of the airway epithelia, which result in acute upper airway obstruction. Massive exposures can override the absorptive surface area of the upper respiratory tract and result in extensive injury to the lower airways and alveoli. Liquid ammonia can freeze the surface of the skin, causing thrombosis of surface vessels, ischemia, and necrosis.

Ammonia gas releases heat as it dissolves and can cause thermal injury. Exposure to high concentrations of ammonia produces severe burns of the cornea and upper airway, respiratory distress, blood-tinged sputum, and stridor.

Toxic doses of ammonia acutely affect cerebral energy metabolism, localized at the base of the brain.

Ammonia toxicity is a major factor in the pathogenesis of hepatic encephalopathy associated with chronic liver disease.

Populations at special risk of exposure to ammonia include individuals with reduced liver function, corneal disease, glaucoma, or chronic respiratory diseases.

Exposure Values:


U.S. manufacturers of ammonia are Agrium US Inc., Borger, TX; Air Products and Chemicals, Inc., East Pace, FL; Allied-Signal Inc, Hopewell, VA; Borden Chemicals and Plastics Operating Limited Partnership, Geismar, LA; CF Industries Inc., Donaldsonville, LA; Chevron Products Corporation, El Segundo, CA; Richmond, CA; Coastal Chem, Inc., Cheyenne, WY; Coastal Refining and Marketing, Inc., St. Helens, OR; Cytec Industries, Westwego (Avondale), LA; Dakota Gasification Company, Beulah, ND; DuPont, Beaumont, TX; Farmland Industries, Inc., Beatrice, NE; Dodge City, KS; Enid, OK; Fort Dodge, IA; Lawrence, KS; Pollock, LA; Green Valley Chemical Corporation, Creston, IA; IMC-Agrico Company, Donaldsonville, LA; IMC Nitrogen Company, East Dubuque, IL; Koch Nitrogen Company, Sterlington, LA; LaRoche Industries Inc, Cherokee, AL; Mississippi Chemical Corporation, Yazoo City, MS; Monsanto Company, St. Louis, MO; St. Louis, MO; Luling, LA; PCS Nitrogen Fertilizer, L.P., Augusta, GA; Clinton, IA; Geismar, LA; La Platte, NE; Memphis, TN; PCS Nitrogen Ohio, L.P., Lima, OH; J R Simplot Company, Pocatello, ID; Terra Industries Inc., Sergeant Bluff, IA; Woodward, OK; Terra Nitrogen, Limited Partnership, Blytheville, AR; Triad Nitrogen, Inc., Donaldsonville, LA; Ultramar Diamond Shamrock Corporation, Dumas, TX; Unocal Corp, Finley, WA; Kenai, AK; and Willard Grain and Feed, Pryor, OK.


The Occupational Safety and Health Administration (OSHA) issues permissible exposure limits for ammonia of 50 ppm, or 35 mg/m3, time-weighted average, and 35 ppm, or 27 mg/m3, short-term exposure. Ammonia as a Highly Hazardous Chemical under the Process Safety Management Standard at a threshold quantity of 10,000 pounds.

Ammonia is regulated under the Clean Water Act; Comprehensive Environmental Response, Compensation, and Liability Act; and the Emergency Planning and Community Right-to-Know Act.

Under Section 302 of the Emergency Planning and Community Right to Know Act of 1986, ammonia is listed as an Extremely Hazardous Substance and has a threshold planning quantity of 10,000 lbs.

Under Section 313 of the Emergency Planning and Community Right to Know Act of 1986 releases of more than one pound of ammonia into the air, water, and land must be reported annually and entered into the Toxic Release Inventory (TRI).

Facilities having a threshold quantity of 10,000lbs of ammonia are subject to the Risk Management Program Rule (RMP), Section 112r of the Clean Air Act. Ammonia has a toxic endpoint of 0.14 mg/L.

National Overview of 1998 Toxic Release Inventory

In 1998, 2,967 facilities released 195,393,942 pounds of ammonia. Of those releases, 155,287,825 pounds were air emissions; 7,498,260 pounds were surface water discharges; 25,790,588 pounds were released by underground injection; 4,592,711 pounds were released to land; and, 2,224,558 pounds were transferred off-site for disposal. Total emissions for 1998 represented a decrease from 1997 emissions, which totaled 199,993,873 pounds; and increase from 1996 emissions, which totaled 194,924,868 pounds; and an decrease from 1995 emissions, which totaled 199,039,536 pounds.

In 1998, 953,071,723 pounds of ammonia waste were managed; 355,672,768 pounds were recycled on-site; 10,368,349 pounds were recycled off-site; 103,213,467 pounds were used for energy recovery on-site; 209,549 pounds were used for energy recovery off-site; 271,379,931 pounds were treated on-site; 16,979,770 pounds were treated off-site; and 195,257,889 pounds were released on-and off-site.

The 10 states in which the largest amounts of ammonia were released in 1998 were Louisianna (27,5668,618 pounds); Texas (25,830,267 pounds); Ohio (13,064,381 pounds); Virginia (8,209,540 pounds); Tennessee (8,157,257 pounds); California (8,047,178 pounds); Georgia (8,029,556 pounds); Florida (7,024,936 pounds); Illinois (6,981,562 pounds); and Iowa (6,005,707 pounds).

The 10 facilities releasing the largest amounts of ammonia in 1998 were: IMC-Agrico Co. Faustina Plant, Saint James, LA (6,435,064 pounds); CF Inds. Inc., Donaldsonville, LA (5,203,700 pounds); PCS Nitrogen Fertilizer L.P., Millington, TN (4,923,721 pounds); Alliedsignal Inc. Hopewell Plant, Hopewell, VA (4,874,000 pounds); Elkem Metals Co., Marietta, OH (3,878,000 pounds); Solutia - Chocolate Bayou, Alvin, TX (3,801,390 pounds); ADM Bioproducts, Decatur, IL (3,500,000 pounds); Sterling Chemicals Inc., Texas City, TX (3,443,440 pounds); Triad Nitrogen Inc., Donaldsonville, LA (3,327,926 pounds); and Du Pont Beaumont Plant, Beaumont, TX (3,243,411 pounds).


The NIOSH recommended exposure limits (RELs) are time-weighted average (TWA) concentrations for up to a 10-hour workday during a 40-hour workweek. A short-term exposure limit (STEL) is designated by "ST" preceding the value; unless noted otherwise, the STEL is a 15-minute TWA exposure that should not be exceeded at any time during a workday. A ceiling REL is designated by "C" preceding the value. Any substance that NIOSH considers to be a potential occupational carcinogen is designated by the notation "Ca."

The OSHA permissible exposure limits (PEL) are found in Tables Z-1, Z-2, and Z-3 of the OSHA General Industry Air Contaminants Standard (29 CFR 1910.1000). Unless noted otherwise, PEL are TWA concentrations that must not be exceeded during any 8-hour workshift of a 40-hour workweek. A STEL is designated by "ST" preceding the value and is measured over a 15-minute period unless noted otherwise. OSHA ceiling concentrations (designated by "C" preceding the value) must not be exceeded during any part of the workday; if instantaneous monitoring is not feasible, the ceiling must be assessed as a 15-minute TWA exposure. In addition, there are a number of substances from Table Z-2 (e.g., beryllium, ethylene dibromide, etc.) that have PEL ceiling values that must not be exceeded except for specified excursions. For example, a "5-minute maximum peak in any 2 hours" means that a 5-minute exposure above the ceiling value, but never above the maximum peak, is allowed in any 2 hours during an 8-hour workday.

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