The annual European Union emission inventory report 1990-2015 under the The United Nations Economic Commission for Europe (UNECE) Convention on Long-range Transboundary Air Pollution (LRTAP) shows that NH3 emissions fell by 23 % between 1990 and 2015, but increased in the EU-28 between 2014 and 2015 by 1.8 %. The other main pollutants covered by the LRTAP Convention have dropped considerably since 1990, including the three air pollutants primarily responsible for the formation of ground-level ozone (O3). Carbon monoxide (CO), non-methane volatile organic compounds (NMVOCs) and nitrogen oxides (NOx) were reduced by 68%, 61 % and 56 % respectively. Around 94 % of ammonia emissions in Europe stem from agriculture, mainly from activities such as manure storage, slurry spreading and the use of inorganic nitrogen fertilizers. Ammonia contributes to eutrophication — an oversupply of nitrogen — and acidification of ecosystems. It also forms particulate matter in the atmosphere which has adverse effects on human health.