'Ammonia (total)' refers to the mixture of two different, but related compounds: ammonia (NH3) and the ionised form (NH4+). The NH3 compound is the volatile, potentially hazardous substance present in the mixture.
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.
Substance name: Ammonia
CASR number: 7664-41-7
Molecular formula: NH3
Synonyms: anhydrous ammonia, aqueous ammonia, ammonium hydroxide, aqua ammonia, ammonia water
Ammonia is a colourless gas with a distinct, pungent odour that is distinctive of drying urine. It is easily liquefied under pressure.
Specific Gravity: 0.7714
Melting Point: -77.7°C
Boiling Point: -33.3°C
Relative Vapour Density: 0.5967
Ammonia is alkaline and corrosive. It reacts strongly with oxidisers, acids, halogens, and attacks copper, aluminium, silver, zinc and their alloys. It is corrosive to copper. Liquid ammonia will attack some forms of plastics, rubbers and coatings. It is very soluble in water, chloroform and ether, and is moderately soluble in alcohol. Ammonia is a good solvent.
The National Pollutant Inventory (NPI) holds data for all sources of ammonia emissions in Australia.
Exposure to typical environmental concentrations of ammonia will not affect humans. Ammonia has been used for a long time in human and veterinary medicine and in smelling salts.
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).
Entering the body
Everyone is exposed to low levels of naturally-occurring ammonia in air, food, water and soil. Exposure to higher levels of ammonia can be from inhaling fumes, from splashing ammonia onto the skin, or from consuming ammonia. It is most likely that ammonia will be inhaled rather than from being absorbed through the skin. Most ammonia inhaled is rapidly exhaled. Ammonia that has been absorbed or ingested is rapidly converted to other non-harmful substances. Remaining ammonia is passed in the urine within a couple of days.
Ammonia is made by humans and nature. Exposure to low levels of ammonia occurs regularly. Exposure to unnaturally high levels of ammonia would result from human activity.
In the workplace, exposure to ammonia can result from use of cleaning products or ammonia fertilisers or from enclosed areas that contain lots of animals (from their wastes), or by leaks and spills at production plants and storage facilities, tank trucks, rail cars, ships and vehicles that transport ammonia.
Workplace exposure standards
Safe Work Australia sets the workplace exposure standard for ammonia through the workplace exposure standards for airborne contaminants:
- Maximum eight hour time weighted average (TWA): 25 parts per million (17 mg/m3)
- Maximum short term exposure limit (STEL): 35 parts per million (24 mg/m3)
These standards are only appropriate for use in workplaces and are not limited to any specific industry or operation. Make sure you understand how to interpret the standards before you use them.
Drinking water guidelines
The Australian Drinking Water Guidelines include the following guidelines for acceptable water quality:
- Maximum of 0.5 milligrams per litre of water for aesthetic considerations
Nitrogen is essential for all forms of life, and ammonia is one of the many forms that nitrogen exists in the environment. At high levels of ammonia, toxic effects can be observed. These may include the death of animals, birds, fish and death or low growth rate in plants. Ammonia (total) refers to the sum of ammonia (NH3) and the ionised form (NH4+). The toxicity is due to the presence of NH3, which increases in concentration with increasing pH levels.
Therefore ammonia is more toxic in more alkaline waters. It is also more toxic under decreased oxygen concentrations. Under normal conditions (temperature and pH), ammonia has moderate toxicity to aquatic life. The short term effects of total ammonia in plants, birds and land animals are not fully known.
Long term effects may include shortened lifespan, reproductive problems, lowered fertility, and changes in appearance or behaviour. These may be seen long after the first exposure to ammonia. Under normal temperature and pH conditions, ammonia has moderate long term toxicity to aquatic life.
Entering the environment
Ammonia occurs naturally in the environment, and is present in air, soil, water, plants and animals. Bacteria in human and animal intestines can produce ammonia. Large concentrations of ammonia can be transported by a number of pathways, by air, water, soil, plants and animals.
Where it ends up
Ammonia is rapidly taken up by plants, bacteria and animals. It is recycled naturally, and nature has many ways of incorporating and transforming ammonia. It does not bioaccumulate in the food chain, but is a nutrient for plants and bacteria.
In 2000, the Australian and New Zealand Environment and Conservation Council (ANZECC) and the Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ) established trigger levels of 320-500 micrograms of ammonia per litre of water.
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. Ammonia is also produced from mining, electricity supply and petroleum refining activities.
Diffuse sources, and industry sources included in diffuse emissions data
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.
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.
Motor vehicles, through their exhaust, produce ammonia.
Many cleaning products, bleaching products and disinfectants contain ammonia.
Sources used in preparing this information
- Agency for Toxic Substances and Disease Registry (ASTDR), ToxFAQs: Ammonia, accessed February 2007.
- Australian and New Zealand Environment and Conservation Council (ANZECC) and Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ) (2000), Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Volume 1, The Guidelines, accessed February 2007.
- Environment Writer Chemical Backgrounder: Ammonia (anhydrous), accessed February 2007.
- Merck and Co. 2001, Merck Index, 13th Edition, USA
- National Pollutant Inventory (1999), Contextual Information.
- Scorecard. Chemical profiles: Ammonia, accessed February 2007.
- Technical Advisory Panel 1999, Final Report to the National Environment Protection Council.
- United Nations, International Chemical Safety Cards: Ammonia (anhydrous), accessed February 2007.
- Safe Work Australia, Workplace exposure standards for airborne contaminants, accessed June 2021.
- National Health and Medical Research Council (NHMRC), Australian Drinking Water Guidelines (2011) - Updated October 2017, accessed May 2018