Indicator air

Ammonia immissions

High concentrations of ammonia cause acute damage to vegetation and lead to acidification and over-fertilisation of soil, which is harmful to ecosystems. In addition, ammonia is an important precursor in the formation of secondary aerosols (fluid particles such as sulphuric acid or nitric acid formed from a chemical reaction with gaseous precursors such as sulphur dioxide or nitrogen oxides). Ammonia is formed when storing farmyard manure/slurry and when applying it to fields. Agricultural livestock management is the principal source.

Assessment of the state
poor poor
Assessment of the trend
unsatisfactory unsatisfactory
rural 2022: 4.99 rural 2021: 4.76 rural 2020: 5.6391135228384 rural 2019: 5.83 rural 2018: 6.0421795068646 rural 2017: 4.77 rural 2016: 4.39 rural 2015: 4.99 rural 2014: 4.4 rural 2013: 4.04 rural 2012: 4.53 rural 2011: 5.24 rural 2010: 4.5 rural 2009: 4.83 rural 2008: 4.31 rural 2007: 4.49 rural 2006: 4.97 rural 2005: 4.57 rural 2004: 4.57

Data for the graph: Excel
Source: FOEN

Source: FOEN

Ammonia levels have scarcely changed over the past ten years and are still significantly above the levels recommended in the Convention on Long-Range Transboundary Air Pollution. Ammonia concentrations are particularly high at locations where large numbers of livestock are kept. In order to achieve a tolerable level in the next few years, ammonia pollution will have to be reduced at a considerably faster rate. In view of this, the trend has to be classified as unsatisfactory.

International comparison

Other European countries also measure ammonia immissions and record similar concentrations.


The concentration of gaseous ammonia (NH3) in the air is determined by means of passive diffusion samplers. The gas is absorbed on an acid-treated filter, and converted thereby into ammonium. The quantity of ammonium retained by the filter can be determined in the laboratory by means of ion chromatography, from which the ammonia concentration can be calculated.

Basis for assessment of the trend
Targeted trend Initial value Final value Variation in % Observed trend Assessment
Decrease Average 2004-2006 Average 2020-2022 9.07% Growth negative*

*Due to the small number of measuring stations and the meteorological influence, it is currently unclear whether the calculated trend is significant. Therefore, the trend is classified as unsatisfactory.

Last updated on: 15.06.2023

Further information




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