Air pollution statistics - air emissions accounts

Data from February 2020

Next update of the article: February 2021

Highlights

Between 2008 and 2017, emissions of acidifying gases (sulphur dioxide, nitrogen oxides and ammonia) in the EU decreased by 24 %.

Between 2008 and 2017, emissions of ozone precursors in the EU decreased by 21 %.


Total ozone precursor emissions, EU-27, 2008 - 2017

This article is about emissions of acidifying gases and ozone precursor substances classified by emitting economic activities. Eurostat records and publishes those in air emissions accounts (AEA), one of the modules in the European environmental economic accounts (for which the legal basis is Regulation (EU) No 691/2011). AEA are suited for integrated environmental-economic analyses such as calculating emission intensities or 'footprints'.

In addition, Eurostat disseminates emissions of air pollutants classified by technical processes. These are recorded in so-called emission inventories for air pollutants and form the official data for international policies on transboundary air pollution. Furthermore, Eurostat estimates and disseminates so-called 'footprints' which are emissions of air pollutants classified by final products that are demanded by households or government, or that are invested in or exported.

Full article

General overview

The EU-27 emissions of acidifying gases (sulphur dioxide (SO2), nitrogen oxides (NOx) and ammonia (NH3)) have been continuously decreasing over the past years. In 2017, emissions of NH3 and NOx contributed around 40 % each while sulphur dioxide contributed with 17 % to the total acidifying potential.

The EU-27 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 2017 the main contributors to the tropospheric ozone formation potential were NOx and NMVOC with 56 % and 32 % respectively.

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.).

Figure 1: Emissions of acidifying gases, EU-27, 2008 - 2017
(thousand tonnes of SO2 equivalents) - Source: Eurostat (env_ac_ainah_r2)

In 2017, emissions of ammonia accounted for the highest share of the acidifying potential (41.8 % or 7 million tonnes of SO2-eq.) followed by nitrogen oxides (39.6 % or 6.6 million tonnes of SO2-eq.) and sulphur dioxide (18.6 % or 3.1 million tonnes of SO2-eq.). The emissions of acidifying gases decreased by 24.1 % between 2008 and 2017. This represents a reduction of 5.3 million tonnes of SO2-eq. emissions. Emissions of sulphur dioxide fell by 51.4 %, nitrogen oxides by 22.7 % and ammonia by 1.3 %. (Figure 1).

Acidifying gas emissions by economic activity

Agriculture, forestry and fishing account for the largest share of all industries: in 2017, these activities contributed 43.6 % of total acidifying gases emitted by industries and households (Figure 2). Ammonia was the largest contributor to the acidifying emissions from agriculture, forestry and fishing with 6.4 million tonnes of SO2-eq. (Figure 3).

The second largest production activity in 2017 was transportation and storage with a share of 22.1 % or 3.7 million tonnes of SO2-eq., followed by manufacturing (10.5 % or 1.7 million tonnes of SO2-eq.). While the largest share of emissions in transport came from NOx, in manufacturing SO2 emissions were predominant (Figure 2 and 3).

Figure 2: Emissions of acidifying gases by economic activity, EU-27, 2008 and 2017
(% of total emissions in SO2 equivalents) - Source: Eurostat (env_ac_ainah_r2)

Most activities recorded significant drops in acidifying emissions. The biggest decrease was observed in electricity, gas, steam and air conditioning supply industry, which dropped from 4 to 1.6 million tonnes of SO2-eq. (60 %) between 2008 and 2017. A 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.

Figure 3: Emissions of acidifying gases by economic activity, EU-27, 2017
(thousand tonnes of SO2 equivalents) - Source: Eurostat (env_ac_ainah_r2)

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 presents the intensities for selected industries in comparison to all NACE industries. It shows that all industries managed to reduce their intensity of acidifying gas emissions between 2008 and 2017. The biggest decrease was recorded in electricity, gas and air conditioning supply with more than 60%.

Figure 4: Intensity of acidifying gas emissions by economic activity, EU-27, 2008 and 2017
(grammes of SO2 equivalents per EUR) - Source: Eurostat (env_ac_aeint_r2)

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, for example, 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 2017 for all pollutants (Figure 5). The emissions of NMVOC, NOx, CO and CH4 decreased by 21 % or 5.6 million tonnes of NMVOC equivalents (NMVOC-eq.). The main pollutants contributing to tropospheric ozone formation were NOx and NMVOC with 56.5 % and 32.4 % respectively (Figure 5). Between 2008 and 2017, the emissions of NOx fell by 22.7 % (or in absolute terms 3.4 million tonnes) and the emissions of CO fell by 24.7 % (or 0.7 million tonnes of NMVOC-eq).

Figure 5: Emissions of ozone precursors, EU-27, 2008 - 2017
(thousand tonnes of NMVOC equivalents ) - Source: Eurostat (env_ac_ainah_r2)

Ozone precursor emissions by economic activity

With 25.9 %, private households were the biggest contributor to total emissions of ozone precursors in 2017; closely followed by the transport industry with 24.4 % . The manufacturing industry was the third largest emitter with 17.6 % (Figure 6).

Between 2008 and 2017, the biggest absolute drop occurred in households (1.4 million tonnes of NMVOC-eq. or 21.2 %). For the same period the biggest relative drop was observed in electricity, gas, steam and air conditioning supply with 34 %.

Figure 6: Emissions of ozone precursors by economic activity, EU-27, 2008 and 2017
(% of total emissions in NMVOC equivalents) - Source: Eurostat (env_ac_ainah_r2)

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 presents the intensities for selected industries in comparison to all NACE industries. It shows that all industries managed to reduce their intensity of ozone precursor emissions between 2008 and 2017. The biggest decrease was recorded in electricity, gas, steam and air conditioning supply with 35%.

Figure 7: Intensity of ozone precursor emissions by economic activity, EU-27, 2008 and 2017
(grammes of NMVOC equivalents per EUR) - Source: Eurostat (env_ac_aeint_r2)

Data sources

The basis for Eurostat’s air emissions accounts is Regulation (EU) No 691/2011 on European environmental economic accounts.

Annual data are transmitted by the EU Member States, as well as the European Free Trade Association (EFTA) countries and some candidate countries.

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 calculating SO2 equivalents the following conversion factors are used: nitrogen oxides 0.7, sulphur dioxide 1.0 and ammonia 1.9. For calculating NMVOC equivalents the following conversion factors are used: nitrogen oxides 1.22, non-methane volatile organic compounds 1.0, carbon monoxide 0.11 and methane 0.014.

In air emissions accounts, emission 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.

Three perspectives of emission statistics for air pollutants

Eurostat presents three perspectives of emission statistics for air pollutants:

Perspective Statistical framework Purpose Related data set Related SE article
1. Emissions of air pollutants classified by economic activities Air Emissions Accounts (AEA) by Eurostat tailored for integrated environmental-economic analyses env_air_aa this article
2. Emissions of air pollutants classified by technical processes Emission inventories for air pollutants by UNECE official international reporting framework for CLRTAP env_air_emis link
3. 'footprints' = GHG emissions classified by final use of products Modelling results published by Eurostat one particular analytical application of AEA env_ac_io10 not available

Emissions accounts versus emission inventories

The main differences between air emissions accounts (AEA) and emission inventories for air pollutants are:

Air emissions accounts – air pollutants (residence principle) Emission inventories for air pollutants (territory principle)
Emissions are assigned to the country where the economic operator causing the emission is resident. Emissions are assigned to the country where the emission takes place
Emissions are classified by economic activity, following the NACE classification of the system of national accounts. Emissions are assigned to processes classified according to their technical nature (e.g. combustion in power plants, solvent use).
Emissions from international navigation and aviation are assigned to the countries where the operator of the ship/aircraft is resident, regardless of where the emission takes place. Emissions from international navigation and aviation are assigned to the countries where the associated fuel is bunkered, irrespective of the operator's place of residence.

Note: National and EU totals differ between the two approaches, as different boundaries apply. GHG inventories include international aviation and maritime transport (international bunker fuels) as memorandum items, which mean that they are excluded from national totals reported. However, they are included in air emissions accounts totals. Therefore total emissions reported in GHG inventory databases can differ significantly from the total reported in air emissions accounts for countries with a large international aircraft and/or shipping fleet. AEA reconciles totals with emission inventories through so-called 'bridging items'.

Context

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, the European Commission’s latest initiative, the European Green Deal.

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