Air pollution statistics - air emissions accounts

Data from November 2016. Most recent data: Further Eurostat information, Main tables and Database Next update of the article: January 2018

This article analyses the emissions to air of five acidifying gases and ozone precursor substances in the European Union (EU) in a breakdown by industries and households that are responsible for their generation. The data source is air emissions accounts reported under the Regulation (EU) No 691/2011 on European environmental economic accounts. The article also briefly explains the differences between air emissions accounts and the data reported under the Convention on Long-Range Transboundary Air Pollution (CLRTAP) in so-called national emission inventories.

The EU-28 emissions of acidifying gases (sulphur dioxide (SO2), nitrogen oxides (NOx) and ammonia (NH3)) have been continuously decreasing over the past years. In 2014, emissions of NH3 and NOx contributed roughly 40 % each while sulphur dioxide contributed around 20 % to the total acidifying potential.

The EU-28 emissions of ozone precursors (nitrogen oxides (NOx), methane (CH4), carbon monoxide (CO) and non-methane volatile organic compounds (NMVOC)) have also been falling over the past years. In 2014 the main contributors to the tropospheric ozone formation potential were NOx and NMVOC with 56 % and 32.4 % respectively.

Figure 1: Emissions of acidifying gases, EU-28, 2008 - 2014
(thousand tonnes of SO2 equivalents) - Source: Eurostat (env_ac_ainah_r2)
Figure 2: Emissions of acidifying gases by economic activity, EU-28, 2009 and 2014
(% of total emissions in SO2 equivalents) - Source: Eurostat (env_ac_ainah_r2)
Figure 3: Emissions of acidifying gases by economic activity, EU-28, 2014
(thousand tonnes of SO2 equivalents) - Source: Eurostat (env_ac_ainah_r2)
Figure 4: Intensity of acidifying gas emissions by economic activity, EU-28, 2009 and 2014
(grammes of SO2 equivalents per EUR) - Source: Eurostat (env_ac_aeint_r2)
Figure 5: Emissions of ozone precursors, EU-28, 2008 - 2014
(thousand tonnes of NMVOC equivalents ) - Source: Eurostat (env_ac_ainah_r2)
Figure 6: Emissions of ozone precursors by economic activity, EU-28, 2009 and 2014
(% of total emissions in NMVOC equivalents) - Source: Eurostat (env_ac_ainah_r2)
Figure 7: Intensity of ozone precursor emissions by economic activity, EU-28, 2009 and 2014
(grammes of NMVOC equivalents per EUR) - Source: Eurostat (env_ac_ainah_r2) and (nama_10_a64))
Table 1: Differences between inventories and accounts
Table 2: Calculation of aggregated environmental pressures

Main statistical findings

Acidifying gases

Several air pollutants contribute to the acidification of the environment. The most important ones are discussed in this article and comprise sulphur dioxide (SO2), nitrogen oxides (NOx) and ammonia (NH3). The impact of SO2, NOx and NH3 can be observed in the progressive degradation of soils, water and forests. They also contribute to the formation of fine particles in the air that cause respiratory diseases. The acidifying potential of SO2, NOx and NH3 is commonly measured in SO2 equivalents (SO2-eq.). The conversion factors are shown in Table 2.

In 2014, emissions of ammonia accounted for the highest share of the acidifying potential (39.8 % or 7.5 million tonnes of SO2-eq.) followed by nitrogen oxides (39.4 % or 7.4 million tonnes of SO2-eq.) and sulphur dioxide (20.8 % or 3.9 million tonnes of SO2-eq.). The emission of acidifying gases decreased by 20.2 % between 2008 and 2014. This represents a reduction of 4.9 million tonnes of SO2-eq. emissions. Emissions of nitrogen oxides fell by 23.4 %, ammonia by 2.1 % and sulphur dioxide by 44.2 % (Figure 1).

Acidifying gas emissions by economic activity

Agriculture, forestry and fishing account for the largest share in all industries: In 2014, these activities contributed 41 % of total acidifying potential emitted by industries, compared with 35 % in 2009 (Figure 2). Ammonia is the largest contributor to the acidifying emissions from agriculture, forestry and fishing with 7.5 million tonnes of SO2-eq (Figure 3). Although it has decreased slightly between 2009 and 2014 by 1.5 %, mainly due to the reduction in livestock numbers, changes in the management of organic manures and the decreased use of nitrogenous fertilisers, it has decreased less than most of the other economic activities discussed in this chapter.

The second largest production activity in 2014 was transportation and storage with a share of 20 % or 3.7 million tonnes of SO2-eq., followed by the electricity, gas, steam and air conditioning supply industry (13 % or 2.5 million tonnes of SO2-eq.). While the largest share of emissions in transport came from NOx, in the electricity, gas, steam and air conditioning supply industry SO2 emissions were predominant (Figure 2 and 3).

All activities recorded significant drops in acidifying emissions. The biggest decrease was observed in electricity, gas, steam and air conditioning supply industry, which dropped from 3.7 to 2.5 million tonnes of SO2-eq. (-33.6 %) between 2009 and 2014. The more systematic use of end-of-pipe pollution filters and the use of more efficient combustion technologies in the electricity and heat production are the main contributors to this development.

Intensity of acidifying gas emissions

The ratio of acidifying gas emissions in tonnes of SO2-eq. per million euros of gross value added (GVA) measures the intensity of acidifying gas emissions of industries (Figure 4). In 2014, agriculture, forestry and fishing showed the highest intensity with 39.4 grammes per euro. This is due to the fact that the agriculture, forestry and fishing industry has large emissions of ammonia and has a comparatively low contribution to the GVA of the economy. Compared to the year 2009 the intensity of acidifying gas emissions decreased in all main industries. The biggest decrease was recorded for manufacturing industry (-31.6 %).

Ozone precursors

Tropospheric ozone occurs when so-called ozone precursor substances (i.e. non-methane volatile organic compounds (NMVOC), nitrogen oxides (NOx), carbon monoxide (CO) and methane (CH4)) react in the lower atmosphere in the presence of sunlight. High ozone levels occur during the warmer summer months as the sun makes e.g. exhaust fumes from vehicles react in the lower atmosphere. High ozone levels are known to damage human tissue and are a health risk, especially for people with respiratory problems. Through the National Emissions Ceilings Directive (NECD) and the Gothenburg Protocol under UNECE-CLRTAP, the EU focuses on the emissions of NOx and NMVOC as they are the most relevant of the four pollutants.

Emissions of ozone precursors in the EU fell between 2008 and 2014 for all pollutants (Figure 5). The emissions of NMVOC, NOx, CO and CH4 decreased by 21 % or 6.1 million tonnes of NMVOC equivalents (NMVOC-eq.). The main pollutants contributing to tropospheric ozone formation are NOx and NMVOC with 56 % and 32.4 % respectively (Figure 6). Between 2008 and 2014, the emissions of NOx fell by 30.5 % or 3.9 million tonnes of NMVOC-eq., and CO by 25.3 % or 0.7 million tonnes of NMVOC-eq.

Ozone precursor emissions by economic activity

With 25 % private households have been the biggest contributor to total emissions of ozone precursors in 2014; closely followed by the transport industry with 24 % . The manufacturing industry is the third largest emitter with 19 % (Figure 6).

Between 2009 and 2014, the biggest absolute drop occurred in transport industry (0.9 million tonnes of NMVOC-eq. or -14.1 %).

Ozone precursor emission intensities

Ozone precursor emission intensity is the ratio of ozone precursor emissions in tonnes of NMVOC equivalents per million euros of gross value added (GVA). Figure 7 shows that in 2014 agriculture, forestry and fishing (15.4 grammes NMVOC-eq. per euro) showed the highest intensity, followed by the electricity, gas, and steam industry and the transportation industry. Compared to year 2009 the intensity decreased in all main industries except mining and quarrying. The biggest decrease was observed in transportation and storage (-18.5 %).

Data sources and availability

Compilation approach

The basis for Eurostat’s air emissions accounts is Regulation (EU) No 691/2011 on European environmental economic accounts. These accounts are compatible with the international United Nations system of national accounts (SNA) and its European Union equivalent, the European system of national and regional accounts (ESA). Furthermore, these accounts follow the national accounts residence principle, which implies that emissions by resident economic units are included even if these occur outside the territory (for example, resident airlines and shipping businesses operating in the rest of the world). These two features make air emissions accounts in particular suitable for integrated environmental-economic analyses and modelling, for example of carbon footprints and climate-change modelling scenarios, which is their main purpose.

Air emissions accounts record national economies’ emissions to the atmosphere with an analysis by emitting economic activity compatible with that used in the ESA. Economic activities comprise production and consumption. ‘Air emission’ means the physical flow of gaseous or particulate materials from the national economy (production or consumption processes) to the atmosphere (as part of the environmental system). Annual data are transmitted by the EU Member States, as well as the European Free Trade Association (EFTA) countries and some candidate countries.

Countries use two approaches for compiling air emissions accounts.

  1. The inventory-first-approach starts from existing national emission inventories and re-arranges those data to a format compatible with national accounts. There is a correspondence to NACE and households for each inventory source code: the Selected Nomenclature for sources of Air Pollution (SNAP), the Common Reporting Framework (CRF), and the Nomenclature For Reporting (NFR). However, the correspondence is not always a one-to-one relationship and certain transformations based on models are required.
  2. The energy-first-approach starts from energy statistics/balances which are rearranged to form energy accounts from which air emissions are calculated using emission factors. Each country applies its individual methodological steps depending on the primary statistical sources available.

Emissions accounts versus emission inventories

In the reporting of emissions of air pollutants (as well as greenhouse gases), two different approaches are internationally established: air emissions accounts and national air emission inventories. The latter are used, for example, for reporting obligations under the Kyoto Protocol. Table 2 shows the main conceptual differences between inventories and accounts. Significant differences between the totals for air emission inventories and air emissions accounts may occur in certain countries where very large resident businesses engage in international water and air transport services. For instance, in Denmark, carbon dioxide emissions reported in the accounts are 95 % higher than those reported in inventories. This difference is due to a very large Danish shipping business operating vessels worldwide and hence bunkering most of its fuel and emitting most of its emissions outside Denmark: these emissions abroad are not accounted for in the Danish emission inventory. For the EU as a whole, the differences between totals from air emissions accounts and from emission inventories are much less pronounced.

SO2 equivalent and NMVOC equivalent

Emissions of individual acidifying gases and ozone precursor substances are converted and aggregated to provide information for the environmental pressures 'acidifying potential' and 'tropospheric ozone formation potential'. They use common units (SO2 equivalent and NMVOC equivalent) to allow comparison and combination of the relative effect of different gases – for example, a single kilogram of ammonia has 1.9 times the acidic effect of a kilogram of sulphur dioxide (see Table 2 for more details on the conversion factors employed).

Analysis by economic activity

In air emissions accounts, the emissions data are organised by economic activity, using NACE. This makes it possible to have an integrated environmental-economic analysis to supplement national accounts. Economic activities encompass production by all businesses resident in a country, including those operating ships, aircraft and other transportation equipment in other countries.

Air emissions accounts also include households as consumers. Their emissions are accounted for whenever household consumption is directly responsible for environmental pressures. For example, emissions from a privately owned car are counted under households, whereas cars owned by transport businesses (such as taxis) are counted under transport services.

The following activity groupings are used in this article:

  • agriculture, forestry and fishing — NACE Rev. 2 Section A;
  • mining and quarrying — NACE Rev. 2 Section B;
  • manufacturing — NACE Rev. 2 Section C;
  • electricity, gas, steam and air conditioning supply — NACE Rev. 2 Section D;
  • transportation and storage — NACE Rev. 2 Section H;
  • other services, water supply and construction — NACE Rev. 2 Sections E to G and I to U, in other words all remaining economic activities as defined in NACE;
  • households — households as consumers.


The need to supplement information on the economy with environmental indicators has been recognised in a European Commission Communication titled 'GDP and beyond'COM(2009) 433). Furthermore, similar recommendations have been made within the Report by the Commission on the Measurement of Economic Performance and Social Progress,the so-called Stiglitz report. The recommendations support the expansion of the statistical understanding of human well-being by supplementing economic indicators such as GDP with additional information, including physical indicators related to the environment.

Air emissions accounts measure the interplay between the economy and the environment with respect to air emissions, in order to assess whether current production and consumption activities are on a sustainable path of development. Measuring sustainable development is a complex undertaking as it has to incorporate economic, social and environmental indicators. The data obtained from air emissions accounts may subsequently feed into political decision-making, underpinning policies that target both continued economic growth and sustainable development, for example, initiatives such as the Europe 2020 strategy, which aims to achieve a resource-efficient, low-carbon economy for the EU by 2020.

See also

Further Eurostat information




Dedicated section

Methodology / Metadata

Source data for tables and figures (MS Excel)

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