In Europe the regional air pollution is regulated by a number of protocols under the UNECE CLRTAP (United Nations Economic Commission for Europe Convention on Long Range Transboundary Air Pollution) Convention.

The objectives of the new protocol – the Gothenburg Protocol – is to control and reduce the emissions of SO₂, NO_x, NMVOC and NH₃. In contrary to the former protocols the parties to the convention are not obliged to comply with certain reduction ratios from a baseline year. Instead emission ceilings have been set from the knowledge of critical loads and environmental impact on ecosystems within the geographical area of Europe. The table shows the emission ceilings for Denmark in 2010 together with the emissions in 2009.

The same emission ceilings are given in the following EU directive also called the NEC-directive:
Directive 2001/81/EC of the European Parliament and of the Council of 23 October 2001 on National Emission Ceilings for certain atmospheric pollutants.