At room temperature, ammonia is a colourless gas with a strong, pungent odour1. Ammonium ions (NH4+) and hydroxide ions (OH-) are formed when ammonia reacts with water.
Ammonia is used within industry for production of artificial fertilizers, nitric acid, amines, paints, fibres, plastics, nylon and explosives. Ammonia is also used in flue gas treatment for reduction of nitrogen oxides and as cooling agent in refrigeration2. Ammonia is available to the general public through products such as artificial fertilizers and alkali cleaning products (e.g. window cleaners and floor cleaners).
Sources and transportation pathways
Ammonia is both produced synthetically and formed naturally by degradation of organic matter containing nitrogen. Handling of fertilizer within agriculture is the single largest source of ammonia emissions in Sweden3. Ammonia is emitted to air, where it is converted into ammonium (NH4+) and is deposited to land, water and vegetation4. The chemical reaction of ammonia to ammonium may occur before or after deposition5.
Effects on environment and health
Deposition of ammonia results in acidification and eutrophication of land and water6. Acidification harms plants and animals, both on land and in water7. When the ground turns acidic, vital nutrients are leached from the soil, which eventually may result in reduced forest growth. Furthermore, metals are released in the ground that can harm decomposing organisms in the ground as well as birds and mammals higher up in the food chain, including humans8. Eutrophication occurs when there is an excess of nutrients (e.g. nitrogen) in land or water9. The abundance of nutrients threatens biological diversity by allowing species that thrive in a nutrient-rich environment to outcompete species that are adapted to a more nutrient-poor environment10.
In concentrated solution, ammonia is strongly corrosive. Ammonia gas causes severe irritation of eyes and mucous membranes. Inhaling highly concentrated ammonia gas may cause difficulty in breathing and lung damage11.
International agreements and regulations
Ammonia is regulated by the UN Convention on Long-range Transboundary Air Pollution (CLRTAP) as well as by the EU National Emissions Ceilings Directive (2001/81/EC) and the EU Industrial Emissions Directive (2010/75/EU). The UN Protocol on PRTRs and the EU E-PRTR regulation regulate how data on ammonia emissions is made available.