Emissions of air pollutants from transport in Europe

With the introduction of policy measures in recent decades, the emissions of most air pollutants from transport in the EU-27 have decreased. Reductions in the road transport sector account for the greatest progress. However, the largest increases came from international aviation and navigation, with emissions of nitrogen oxides, sulphur oxides, particulate matter, ammonia and nitrous oxide rising in aviation, and methane emissions increasing in navigation. Most pollutants have rebounded since 2020, when they fell together with transport volumes during the COVID-19 pandemic.

Figure 1. Emissions of pollutants from transport in EU-27

Pollutants emitted by transport activities contribute to ambient air pollution and put significant pressure on the environment and human health. European policy efforts in recent decades have addressed transport-related air pollution in road, rail, aviation and maritime modes of transport, leading to some notable improvements.

Together, such policies have delivered progress in reducing the emissions of many pollutants from the transport sector. Across the EU-27 Member States, between 1990 and 2023, emissions of nitrogen oxides (NO_x) from transport decreased by 53%, sulphur oxides (SO_x) by 82%, and carbon monoxide (CO) by 90%. Methane (CH₄) and non-methane volatile organic compounds (NMVOCs) by 76% and 91%, respectively.

In the same time frame, EU-27 transport emissions of particulate matter with a particle diameter of 10µm (PM₁₀) and 2.5µm (PM_2.5) or less, including non-exhaust emissions, decreased by 47% and 59%, respectively. While a significant reduction can be seen for both PM₁₀ and PM_2.5, the non-exhaust fraction of these emissions, from brake and tyre wear or road abrasion for example, is increasing in percentage. This constituted 77% and 60% of PM₁₀ and PM_2.5 emissions from road transport in 2023 and is expected to become even more relevant with the progressive decarbonisation of the sector and increases in vehicle mass due to greater prevalence of heavier electric vehicles within fleet composition.

Between 1990 and 2023, transport emissions of ammonia (NH₃) increased by 123% while nitrous oxide (N₂O) increased by 34%. The increases of these two air pollutants are concerning. NH₃ emitted in cities has a very high impact on air quality, due to its role in the formation of particulate matter, including ultrafine particles (0.1µm or less in diameter). Ultrafine particles are critical in terms of health effects, as they constitute the largest part of the inhalable fraction of particulate matter. Meanwhile, N₂O, a powerful greenhouse gas, is also currently considered a dominant ozone depleting substance. In road transport, the growth of NH₃and N₂O is mostly due to the use of selective catalytic systems for the reduction of NO_x in diesel engines and the use of enriched fuel mixtures to control NO_x at high load in petrol engines.

Figure 2. Variations (1990-2023) in the emissions of pollutants from transport by mode in EU-27

Total emissions from the aviation sector (both domestic and international) increased for most pollutants (except CH₄, CO, and NMVOCs), with growth since 1990 ranging from 80% and 140% depending on the compound considered. Emission trends from international aviation are higher than those from domestic aviation for several pollutants, namely NO_x, SO_x, PM, NH₃ and N₂O. This is mostly driven by increasing activity levels and inherently greater emissions per flight.

In the navigation sector, emissions from domestic navigation have fallen since 1990 for all the pollutants considered except NH₃, which increased by 28%. The reductions range from 8.2% to 90.1% depending on the compound considered. International navigation has also seen a reduction in several air pollutants, including NH₃, NO_x, PM₁₀, PM_2.5 and SO_x, between 1990 and 2023. Others have increased over the same time period, with CH₄ emissions rising by 109%, mainly due to the widespread adoption of LNG-fueled engines in internatinal shipping, which produce significant methane slip.

Supporting information

Definition

The indicator measures the relative change (in %) in the emissions of different pollutants (CO, NO_x, NMVOCs, SO_x, NH₃, CH₄, N₂O, PM₁₀, PM_2.5) in the transport sector as a whole and for different subsectors. Relative variations were indexed with respect to year 1990 for all pollutants.

List of abbreviations

PM_2.5/ PM₁₀: particulate matter with aerodynamic diameter of 2.5μm/10μm or less respectively, including non-exhaust emissions.
NMVOCs: non-methane volatile organic compounds
SO_x: sulphur oxides
NO_x: nitrogen oxides
CO: carbon monoxide
NH₃: ammonia
CH₄: methane
N₂O: nitrous oxide

Methodology

For CO, NO_x, NMVOCs, SO_x, NH₃, PM₁₀ and PM_2.5, data officially reported to the European Monitoring and Evaluation Programme (EMEP)/LRTAP Convention were used. For CH₄ and N₂O data officially reported under the United Nations Framework Convention on Climate Change (UNFCCC) and also under the Kyoto Protocol (KP) were used.

Where a complete time series of emission data has not been reported for CO, NO_x, NMVOCs, SO_x, NH₃, PM₁₀ and PM_2.5, data have been gap filled according to the methodologies of the European Environment Agency's (EEA's) European Topic Centre on Air and Climate Change (ETC/ACC). Details of the gap-filling procedure for the air pollutant data set are described in the EU emission inventory report under the UNECE's Convention on LRTAP. Similarly, for CH₄ and N₂O additional information on the gap-filling procedure can be found in the Annual European Union greenhouse gas inventory and inventory document.

Policy/environmental relevance

The mobility system contributes to overall air pollution emissions and air quality deterioration across Europe. Additional information on its relative contribution to the overall situation in Europe can be found by consulting the EEA interactive data viewer, while up-to-date information on air quality in Europe can be found in the EEA interactive maps.

For instance, since 2008, the Ambient air quality Directive has set limits or target values for concentrations of pollutants in the ambient air, while the NEC Directive has set emission reduction commitments since 2016 for total national emissions for five air pollutants (NO_x, SO₂, NMVOCs, NH₃ and PM_2.5). Recently, the European Commission proposed a revision of the Ambient air quality Directive, to more closely align air quality standards with WHO guidelines, while putting the EU on a trajectory to achieve the zero pollution ambition by 2050.

Emissions from the transport sector are further regulated by vehicle emissions standards (for new cars and light commercial and heavy-duty vehicles) and fuel quality requirements. Local and regional air quality management plans, including initiatives such as low-emission zones and congestion charges in cities, are active in many areas. SO_x and NO_x emissions from international shipping are regulated by Annex VI to MARPOL Convention of the International Maritime Organisation. SO_x requirements are transposed in EU law by the Directive on sulphur content in certain liquid fuels including marine fuels. Aviation emission of NO_x and nvPM are regulated at ICAO level.

Transport emissions of ammonia (NH₃) and nitrous oxide (N₂O) are increasing and are of concern: NH₃ emitted within the cities have a very high impact on air quality; N₂O, beside a powerful greenhouse gas, is also currently considered a dominant ozone depleting substance.

Accuracy and uncertainties

For CO, NO_x, NMVOCs, SO_x, NH₃, PM₁₀ and PM_2.5, data officially reported to the European Monitoring and Evaluation Programme (EMEP)/LRTAP Convention were used. For CH₄and N₂O data officially reported under the United Nations Framework Convention on Climate Change (UNFCCC) and also under the Kyoto Protocol (KP) were used.

Where a complete time series of emission data has not been reported for CO, NO_x, NMVOCs, SO_x, NH₃, PM₁₀ and PM_2.5, data have been gap filled according to the methodologies of the European Environment Agency's (EEA's) European Topic Centre on Air and Climate Change (ETC/ACC). Details of the gap-filling procedure for the air pollutant data set are described in the EU emission inventory report 1990-2022 under the UNECE's Convention on LRTAP. Similarly, for CH₄ and N₂O additional information on the gap-filling procedure can be found in the Annual European Union greenhouse gas inventory 1990–2022 and inventory document 2024, First submission under the Enhanced Transparency Framework of the Paris Agreement.

Data sources and providers

Metadata

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Emissions of air pollutants from transport in Europe

Figure 1. Emissions of pollutants from transport in EU-27

Figure 2. Variations (1990-2023) in the emissions of pollutants from transport by mode in EU-27

Supporting information

Metadata

References and footnotes