Aarhus Universitets segl

No. 488: Annual Danish Informative Inventory Report to UNECE. Emission inventories from the base year of the protocols to year 2020

Nielsen, O-K., Plejdrup, M.S., Winther, M., Mikkelsen, M.H., Nielsen, M., Gyldenkærne, S., Fauser, P., Albrektsen, R., Hjelgaard, K.H., Bruun, H.G. & Thomsen, M. 2022. Annual Danish Informative Inventory Report to UNECE. Emission inventories from the base year of the protocols to year 2020. Aarhus University, DCE – Danish Centre for Environment and Energy, 583 pp. Scientific Report No. 488 http://dce2.au.dk/pub/SR488.pdf


I Background information on emission inventories

Annual report

This report is Denmark’s Annual Informative Inventory Report (IIR) due March 15, 2022 under the UNECE-Convention on Long-Range Transboundary Air Pollution (LRTAP) and Directive (EU) 2016/2284 on the reduction of national emissions of certain atmospheric pollutants. The report contains information on Denmark’s inventories for all years from the base years of the protocols to 2020.

The air pollutants reported are SO2, NOX, NMVOC, CO, NH3, TSP, PM10, PM2.5, BC, As, Cd, Cr, Cu, Hg, Ni, Pb, Se, Zn, PCDD/F, HCB, PCBs, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene and indeno(1,2,3-cd)pyrene.

The annual emission inventory for Denmark is reported in the Nomenclature for Reporting (NFR) 2019 format.

The issues addressed in this report are trends in emissions, description of each NFR category, uncertainty estimates, recalculations, planned improvements and procedures for quality assurance and control. The structure of the report follows to the extent possible the proposed outline.

Information contained in this report is available to the public on the Danish Centre for Environment and Energy (DCE), Aarhus University’s homepage:


This report and the NFR tables are available on the Eionet central data repository:




Responsible institute

DCE-Danish Centre for Environment and Energy, Aarhus University, is on behalf of the Danish Ministry of Environment and Food responsible for the annual preparation and submission of the Annual Informative Inventory Report and the inventories in the NFR format to the UNECE-LRTAP Convention and the European Commission. DCE participates in meetings under the UNECE Task Force on Emission Inventories and Projections and the related expert panels, where parties to the convention prepare the guidelines and methodologies on inventories.

II Trends in emissions

Acidifying gases

In 1990, the relative contribution in acid equivalents was almost equal for the three gases SO2, NOx and NH3. In 2020, the most important acidification factor in Denmark is ammonia nitrogen and the relative contributions for SO2, NOX and NH3 were 4 %, 29 % and 67%, respectively. However, with regard to long-range transport of air pollution, SO2 and NOX are still the most important pollutants.

Sulphur dioxide (SO2)

The main part of the sulphur dioxide (SO2) emission originates from combustion of fossil fuels, i.e. mainly coal and oil, in public power and district heating plants. Since 1990, the total emission has decreased by 95 %. The large reduction is mainly due to installation of desulphurisation and use of fuels with lower content of sulphur in public power and district heating plants. Despite the large reduction of the SO2 emissions, these plants make up 23 % of the total emission. In addition, emissions from industrial combustion plants, non-industrial combustion plants and other mobile sources are important.

Nitrogen oxide (NOx)

The largest sources of emissions of nitrogen oxides (NOx) are road transport followed by other mobile sources and combustion in energy industries (mainly public power and district heating plants). The transport sector is the sector contributing the most to the emission of NOx and, in 2020, 38 % of the Danish emissions of NOx stems from road transport, national navigation, railways and civil aviation. In addition, emissions from national fishing and off-road vehicles contribute significantly to the NOx emission. For non-industrial combustion plants, the main sources are combustion of gas oil, natural gas and wood in residential plants. The emissions from energy industries have decreased by 86 % from 1990 to 2020. In the same period, the total emission decreased by 70 %. The reduction is due to the increasing use of catalyst cars and installation of low-NOx burners and denitrifying units in power plants and district heating plants.

Ammonia (NH3)

Almost all atmospheric emissions of ammonia (NH3) result from agricultural activities. Only a minor part of the total emission originates from stationary combustion (2.0 %), road transport (1.0 %), industrial processes (0.5 %) and waste (0.9 %). The share for road transport was increasing during the 1990’s and early 2000’s due to increasing use of catalyst cars. In recent years, the share has been decreasing due to more advanced catalysts being implement-ed.

The major part of the emission from agriculture stems from livestock manure (43 %) and agricultural soils (52 %). The largest source for manure management is losses of ammonia occur during the handling of the manure in animal housing systems. For agricultural soils, the emissions are mainly stemming from application of mineral fertiliser, application of animal manure and growing crops. The total ammonia emission has decreased by 46 % since 1990.

Due to the action plans for the aquatic environment and the Ammonia Action Plan, a series of measures to prevent loss of nitrogen in agricultural production has been initiated. The measures have included demands for improved utilisation of nitrogen in livestock manure, a ban against field application of livestock manure in winter, prohibition of broadspreading of manure, requirements for establishment of catch crops, regulation of the number of livestock per hectare and a ceiling for the supply of nitrogen to crops. As a result, despite an increase in the production of pigs and poultry, the ammonia emission has been reduced considerably.

Other air pollutants

Non-methane volatile organic compounds (NMVOC)

The emissions of Non-Methane Volatile Organic Compounds (NMVOC) originate from many different sources and can be divided into two main groups: incomplete combustion and evaporation. Small combustion plants (e.g. residential wood burning) is a big source of NMVOC originating from combustion. Other sources are road vehicles and other transport sources such as national navigation vessels contribute approximately 5.6 % of the NMVOC emissions from combustion processes. NMVOC from road transportation vehicles have been decreasing since 1990, due to the introduction of catalyst cars. The evaporative emissions mainly originate from the agricultural sector, use of solvents, and the extraction, handling and storage of oil and natural gas. The total anthropogenic emissions have decreased by 50 % since 1990, largely due to the increased use of catalyst cars and reduced emissions from use of solvents.

Particulate Matter (PM)

The particulate matter (PM) emission inventory is reported for the years 1990 onwards. The inventory includes the total emission of particles TSP (Total Suspended Particles), emission of particles smaller than 10 µm (PM10) and emission of particles smaller than 2.5 µm (PM2.5).

The largest PM2.5 emission source is residential plants (51 %), road transport (10 %) and other mobile sources (8 %). Emissions from residential plants increased by 58 % from 1990 to 2007, followed by a decrease of 56 % from 2007 to 2020. The increase was caused by increasing wood consumption while the decrease has been caused by a slightly lower wood consumption (until 2016) combined with legislative demands on new wood stoves and boilers. From 2016, the wood consumption decreased significantly leading to a significant decrease in emissions. For the road transport sector, exhaust emissions account for less than half (27 %) of the emissions, while the remaining emissions come from tyre and brake wear and road abrasion. For other mobile sources, the most important sources are off-road vehicles and machinery in the industrial sector and in the agricultural/forestry sector (15 % and 36 %, respectively). The PM2.5 emission decreased by 48 % from 1990 to 2020, but most of the reduction has occurred after 2007.

The largest TSP emission sources are agriculture and non-industrial combustion (76 % and 10 % of total TSP emission in 2020, respectively). Residential plants is the largest source in the non-industrial combustion sector, making up 8 % of the national total TSP emission in 2020.The TSP emissions from transport are also important and include both exhaust emissions and the non-exhaust emissions from brake and tyre wear and road abrasion. The non-exhaust emissions account for 88 % of the TSP emission from road transport in 2020.

Black carbon (BC)

The black carbon (BC) emission inventory is reported for the years 1990 onwards. The main sources are residential plants and road transport contributing 39 % and 19 % in 2020, respectively. From 1990 to 2020, the total BC emission decreased by 66 %. The trend for non-industrial combustion is mainly controlled by the trend for the wood consumption in the residential sector.

BC emissions from the transport sector decreased by 83 % from 1990 to 2020, mainly due to implementing of new EURO norms and improved technology. An important factor is the use of particle filters for heavy-duty vehicles and passenger cars, which reduce the BC emission effectively.

BC emissions from fugitive emissions from fuels, which is mainly due to storage of coal, decreased by 89 % from 1990 to 2020, in line with the decrease in the coal consumption within electricity and heat production.

Heavy metals

In general, the most important sources of heavy metal emissions are combustion of fuels and waste. The heavy metal emissions have decreased substantially in recent years, except for Cu. The reductions span from 20 % to 93 % for Zn and Hg, respectively. The reason for the reduced emissions is mainly increased use of gas cleaning devices at power and district heating plants (including waste incineration plants). The large reduction in the Pb emission is due to a gradual shift towards unleaded gasoline, the latter being essential for catalyst cars. The major source of Cu is automobile tyre and break wear (93 % in 2019) and the 23 % increase in total emission from 1990 to 2020 owe to increasing mileage.

III Recalculations and Improvements

In general, considerable work is being carried out to improve the inventories. Investigations and research carried out in Denmark and abroad produce new results and findings, which are given consideration and, to the extent, which is possible, are included as the basis for emission estimates and as data in the inventory databases. Furthermore, the updates of the EMEP/EEA Guidebook, and the work of the Task Force on Emission Inventories and its expert panels are followed closely in order to be able to incorporate the best scientific information as the basis for the inventories.

The implementation of new results in inventories is made in a way so that improvements, as far as possible, better reflect Danish conditions and circumstances. This is in accordance with good practice. Furthermore, efforts are made to involve as many experts as possible in the reasoning, justification and feasibility of implementation of improvements.

In improving the inventories, care is taken to consider implementation of improvements for the whole time series of inventories to make it consistent. Such efforts lead to recalculation of previously submitted inventories. This submission includes recalculated inventories for the whole time series. A description of the recalculations is provided in Chapter 9 and more detail can be found in the sectoral chapters of this report. For sector specific planned improvements, please also refer to the relevant sectoral chapters.