Ammonia or azane is a compound of nitrogen and hydrogen with the formula NH3. [1] It is a colourless highly irritating gas with a sharp suffocating odour. Ammonia dissolves easily in water to form ammonium hydroxide solution, which can cause irritation and burns. Ammonia gas is easily compressed and forms a clear, colourless liquid under pressure. It is not highly flammable, but containers of ammonia may explode when exposed to high heat. [2] Ammonia gas can be dissolved in water. This kind of ammonia is called liquid ammonia or aqueous ammonia. Once exposed to open air, liquid ammonia quickly turns into a gas. Ammonia occurs naturally and is produced by human activity. It is an important source of nitrogen, which is needed by plants and animals. Bacteria found in the intestines can produce ammonia. [3]


Ammonia is used widely in many areas. It is present in commonly used household and industrial cleaners, bleaching agents and disinfectants. It is used in the preparation of synthetic fibres (e.g. nylons), plastics and explosives, resins, human and veterinary medicines, fertilisers, chemical compounds, fuel cells, rocket fuel, dyes, metal treating operations, refrigeration, and in the petroleum industry.

Sources of Emission [4]

  • Industry sources: Ammonia is released during intensive livestock production, and from humans and pets. Other sources of ammonia emission include the manufacture of basic chemicals, metals, leather products, cement, lime, plaster and concrete products, glass products, ceramics, beverages, cars and car parts, textile products and paper and paper products. In addition, ammonia is produced from mining, electricity supply and petroleum refining activities.
  • Diffuse sources: Human and pet metabolic processes, cigarette smoke and household cleaners are sources of ammonia. Burning, through controlled fires or wildfires, or of other fuels also results in ammonia emissions. Indoor residential levels of ammonia can be significantly higher than outdoor levels.
  • Natural sources: Ammonia is found in the environment, in the air, soil and water, in plants and animals. It is formed naturally by the decomposition of urine and manure. It is a source of nitrogen, which is needed by plants and animals. It has also been observed in outer space and galactic dust clouds.
  • Transport sources: Motor vehicles, through their exhaust, produce ammonia.
  • Consumer products: Many cleaning products, bleaching products and disinfectants contain ammonia.

Sources of Exposure & Routes of Exposure [5]

Sources of Exposure

  • Ammonia is found naturally in the environment. The general population is most likely to be exposed through inhalation of contaminated indoor air, although exposure can also occur through ingestion of contaminated food or water, or through dermal contact.
  • In indoor air, exposure may occur through use of household products such as window cleaners, floor waxes and smelling salts.
  • In outdoor air, exposure may occur as a result of gas leaks and spills at production plants and storage facilities or from pipelines, tank trucks, railcars, ships and barges that transport ammonia.
  • Ammonia is released into the atmosphere naturally by decaying organic matter, animal excreta and volcanic eruptions. It is released anthropogenically through fertiliser usage, spills or leaks, and loss from wastewater effluents.
  • Farmers, cattle ranchers and individuals who raise livestock and/or poultry may be exposed to ammonia from decaying manure.
  • Farmers may also be exposed to ammonia during the application of fertilisers on fields.

Routes of Exposure

  • Inhalation ⁠— Predominant route of exposure for general population
  • Oral ⁠— Minor route of exposure for the general population through ingestion of contaminated drinking water.
  • Dermal ⁠— Minor route of exposure through dermal contact with cleaning products containing ammonia.

Health Effects [4,5]

Exposure to high levels of ammonia can cause irritation and serious burns on the skin, and in the mouth, throat (laryngitis), lungs (pulmonary oedema) and eyes (conjunctivitis). Exposure at very high levels of ammonia can lead to death. Swallowing concentrated solutions of ammonia can cause burns in the mouth, throat and stomach. Splashing ammonia into the eyes can cause burns and blindness. Individuals that may be more sensitive to ammonia are those with reduced liver function, corneal disease, glaucoma or respiratory diseases (e.g. asthmatics). Ammonia has not been classified for carcinogenic effects by the DHHS, or IARC or EPA.

Safety [6]

First Aid Measures

  • Inhalation: Remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention immediately.
  • Ingestion: If swallowed, DO NOT INDUCE VOMITING. Give large quantities of water. Never give anything by mouth to an unconscious person. Get medical attention immediately.
  • Skin Contact: Immediately flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Get medical attention immediately. Wash clothing before reuse. Thoroughly clean shoes before reuse.
  • Eye Contact: Immediately flush eyes with plenty of water for at least 15 minutes, lifting lower and upper eyelids occasionally. Get medical attention immediately.
  • Note to Physician: DO NOT induce emesis, perform gastric lavage or attempt neutralisation after ingestion. Dilution with milk or water may be of benefit. Endoscopic evaluation may be required.

Fire Fighting Measures

  • Explosion: Gives off flammable vapours. Vapours may form explosive mixture with air. Closed containers exposed to heat may explode.
  • Fire Extinguishing Media: Use any means suitable for extinguishing surrounding fire. Water spray may be used to keep fire-exposed containers cool. Do not allow water runoff to enter sewers or waterways.
  • Special Information: In the event of a fire, wear full protective clothing and NIOSH-approved self-contained breathing apparatus with full face-piece operated in the pressure demand or other positive pressure mode.

Exposure Controls & Personal Protection

  • Ventilation System: A system of local and/or general exhaust is recommended to keep employee exposures below the Airborne Exposure Limits. Local exhaust ventilation is generally preferred because it can control the emissions of the contaminant at its source, preventing dispersion of it into the general work area
  • Personal Respirators (NIOSH Approved): If the exposure limit is exceeded, a full face piece respirator with an ammonia/methylamine cartridge may be worn up to 50 times the exposure limit or the maximum use concentration specified by the appropriate regulatory agency or respirator supplier, whichever is lowest. For emergencies or instances where the exposure levels are not known, use a full-face piece positive-pressure, air-supplied respirator.
  • WARNING: Air purifying respirators do not protect workers in oxygen-deficient atmospheres.
  • Skin Protection: Wear impervious protective clothing, including boots, gloves, lab coat, apron or coveralls, as appropriate, to prevent skin contact.
  • Eye Protection: Use chemical safety goggles and/or a full face shield where splashing is possible. Maintain eye wash fountain and quick-drench facilities in work area.

Regulation [3,4,6]

Exposure Limits

  • United States

  • The Food and Drug Administration (FDA): Some restrictions have been placed on levels of ammonium salts allowable in processed foods. FDA states that the levels of ammonia and ammonium compounds normally found in food do not pose a health risk.
  • The Occupational Safety and Health Administration (OSHA) has set an acceptable eight-hour exposure limit at 25 parts of ammonia per one million parts of air (ppm) and a short-term (15 minutes) exposure level at 35 ppm
  • American Conference of Industrial Hygienists (ACGIH): Threshold Limit Value (TLV) 25 ppm (TWA), 35 ppm (STEL).
  • Australia

  • Safe Work Australia: Currently, the eight-hour time weighted average (TWA) exposure limit is 17 milligrams of ammonia per cubic metre of air, and the 15-minute short-term exposure limit (STEL) is 24 milligrams of ammonia per cubic metre of air.
  • Drinking water guidelines: In 2004, the National Health and Medical Research Council (NHMRC) and the National Resource Management Ministerial Council (NRMMC) established the following guideline for acceptable water quality: Maximum of 0.5 milligrams per litre of water. This is based on aesthetic consider.