High concentrations of ammonia (NH3) 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.
Emissions are determined by multiplying the annual human activity rates by pollutant-specific emission factors. Data are gathered by means of surveys, modelling and calculations.