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NH3, ammonia gas, aqueous ammonia or ammonium hydroxide (when dissolved in water)

SPRI Emission Reporting Threshold
1,000 Kg/yr Pollutant Emissions to Air
20.0 Kg/yr Pollutant Emissions to Waste Water
20.0 Kg/yr Pollutant Emissions to Water
This sheet is a generic summary, designed to give the reader a basic level of background information about the substance in question. Great care has been taken to represent as effectively and correctly as possible the broad range of (not necessarily consistent) information which is available from a variety of sources. The reader must accept therefore that this sheet has no legal status and cannot be relied upon in any legal proceedings. SEPA disclaims any responsibility or liability whatsoever for errors and omissions in this sheet.
What is it?
Ammonia is a common naturally occurring substance. It is also manufactured by man. At normal environmental conditions, pure ammonia is a colourless, pungent-smelling, caustic (corrosive) gas. It is stored under high pressure as a liquid. It is highly soluble in water and reacts with acids to form ammonium salts.
What is it used for?
Ammonia is used in a variety of ways: for bleaching or cleaning, in the production of fertilisers, plastics, pharmaceuticals, rubber and petrochemicals and as an anti-fungal agent for foodstuffs.
Where does it come from?
The main sources of ammonia are natural: from decaying organic matter and from the excreta of humans and animals. Man-made sources (such as from the use of fertilisers and waste disposal sites or industrial processes) are smaller.
How might it affect the environment?
The main local problem of ammonia released into air is the unpleasant odour, which is detectable even at low concentrations. At particularly high concentrations it can also harm vegetation. The harm caused by ammonia in water bodies is more serious, because it is very toxic to aquatic organisms. Low concentrations of ammonia in soil are natural and actually essential for plant nutrition. Over-fertilisation can however lead to excessive concentrations which result in leaching to water bodies. On a wider scale, ammonia plays a role in the transportation and enhanced deposition of acidic pollutants - resulting in acidification of ground and water bodies, which can harm plant and animal life.
How might exposure to it affect human health?
Exposure to ammonia at environmental concentrations is unlikely to have adverse effects on health. However, exposure to high concentrations following an accidental release or in occupational settings could cause irritation of the eyes, nose and throat as well as burning the skin where there is direct contact.
What steps are being taken to limit the potential impacts?
UK (including Scottish) releases of ammonia are controlled under the Pollution Prevention and Control (PPC) regulations; and regulations on releases to surface waters. European laws also control releases to air and water; releases from industrial plants (84/360/EEC); and ammonia pollution of the aquatic environment (76/464). Internationally, the UK is a signatory to the international UNECE Convention on Long-Range Transboundary Air Pollutants (LRTAP); and the Gothenburg UN/ECE Protocol to abate acidification, eutrophication (where over-fertilisation causes water bodies to become "choked" with weeds) and formation of ground level ozone.