Indicator Assessment

Emissions of air pollutants from transport

Indicator Assessment
Prod-ID: IND-112-en
  Also known as: TERM 003
Published 05 Dec 2017 Last modified 11 May 2021
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  • Between 1990 and 2015, the transport sector significantly reduced emissions of certain air pollutants: carbon monoxide (CO) and non-methane volatile organic compounds (NMVOCs) (both by around 85%), sulphur oxides (SOx) (49 %), nitrogen oxides (NOx) (41 %). Since, 2000 a reduction in particulate matter emissions (42 % for PM2.5 and 35 % for PM10) has occurred.
  • Emission reductions from road transport have been lower than originally anticipated over the last two decades. This is partly because transport has grown more than expected and, for certain pollutants, partly owing to the larger than expected growth in diesel vehicles, which produce higher NOx and PM emissions than petrol-fuelled vehicles. Furthermore, it is widely accepted that 'real-world emissions' of NOx, particularly from diesel passenger cars and vans, generally exceed the permitted European emission (Euro) standards, which define the acceptable limits for exhaust emissions of new vehicles sold in the EU Member States.
  • Emissions of all pollutants decreased in 2015 compared with the previous year. NOx emissions decreased by 1 %, SOby 12 %, and PM10 and PM2.5 by 4 % and 5 %, respectively. The latest data show that non-exhaust emissions of primary PM10 and PM2.5, such as from tyre- and brake-wear, make up 55 % and 37 % of total transport emissions of these pollutants, respectively. 
  • All transport modes have reduced their emissions since 1990, except for international aviation and shipping for which CO, NOx and SOx emissions of each pollutant have increased.

Contribution of the transport sector to total emissions of the main air pollutants


Trend in emissions of air pollutants from transport

Transposed table

Progress has been made since 1990 in reducing the emissions of many air pollutants from the transport sector.

The relative changes in emissions of pollutants from the transport sector are shown in the above figures. Emissions from all transport types have declined since 1990, despite the general increase in activity within the sector since this time. Between 1990 and 2015, emissions of NOx from transport declined by 41 %, those of SOx by 49 %, CO by 85 % and NMVOCs by 86 %, across the EEA-33. By 215, emissions of PM2.5 had decreased by 42 % from 2000 levels.

The scale of policy actions undertaken in Europe to specifically address transport-related air pollution has increased over recent years, reflecting the important contribution that transport still makes in relation to poor air quality. Local and regional air quality management plans  including initiatives such as low-emission zones in cities or congestion charges — are now undertaken in many areas where air pollution from transport is high. Different European legal mechanisms are used to address air quality (including that influenced by traffic related sources). These include the setting of limit or target values for ambient concentrations of pollutants, limits on total emissions (e.g. national totals) and regulating emissions from the traffic sector either by setting emission standards (like EURO 1-6) or by setting requirements for fuel quality.

Reductions from the road transport sector contribute to the majority of the overall reductions for each pollutant, as shown in the figures above. In contrast, since 1990, international aviation (except NMVOC emissions) and shipping (except PM10 emissions) are the only transport sub-sectors for which emissions of each pollutant have actually increased. Emissions of NH3 from road transport have also increased, although they contribute only a very small fraction of total NH3 emissions. Emissions of NOx from international aviation have more than doubled (+123 %) since 1990, while NOx and NMVOC emissions from international shipping have both increased by around 19 % and 13 %, respectively and PM2.5 emissions have declined by 26 % since 2000. As emissions of pollutants such as NOx and SOx from land-based sources decrease, there is a growing awareness of the increasingly important contribution made to Europe's air quality by the national and international shipping sectors, which now are responsible for 24 % and 20 % of NOx and SOx emissions, respectively.

Transport is responsible for more than half of all NOx emissions and contributes significantly (around 13 % or more) to the total emissions of the other pollutants. Road transport, in particular, continues to make a significant contribution to emissions of all the main air pollutants (with the exception of SOx). While emissions from road transport are mostly exhaust emissions arising from fuel combustion, non-exhaust releases contribute to both NMVOCs (from fuel evaporation) and primary PM (from tyre- and brake-wear, and road abrasion). Also, while emissions of primary PM2.5 from road transport have declined by 50 % since 2000, the relative importance of non-exhaust emissions has increased as a result of the introduction of vehicle particulate abatement technologies, which have reduced exhaust emissions. In 2015, the non-exhaust emissions of PM2.5 constituted 37 % of emissions from the road transport sector, compared with just 1 % in 2000 (for PM10 the contribution increased from 29 % in 2000 to 55 % in 2015).

Supporting information

Indicator definition

This indicator is based on the assessment of emissions trends of CO, NOx, NMVOCs, SOx and primary particulates. 


Emissions are expressed as a percentage of 1990 levels (except for PM emissions, which are expressed as a percentage of 2000 levels).


Policy context and targets

Context description

Directive 2008/50/EC (EC, 2008) sets limit values for the atmospheric concentrations of the main pollutants, including sulphur dioxide (SO2), nitrogen dioxide (NO2), airborne PM (PM10 and PM2.5), lead, CO, benzene and ozone (O3) for EU Member States. These limits are related to transport implicitly, but the introduction of progressively stricter Euro emissions standards and fuel quality standards has led to substantial reductions in air pollutant emissions. Policies aimed at reducing fuel consumption in the transport sector, to cut greenhouse gas emissions, may also help to further reduce air pollutant emissions.

Iceland, Liechtenstein, Norway, Switzerland and Turkey are not members of the EU and hence have no emission ceilings set under the revised National Emission Ceilings Directive (NECD), Directive (EU) 2016/2284. As well as most of the EU Member States, Norway and Switzerland have ratified the 1999 United Nations Economic Commission for Europe (UNECE) Convention on Long-Range Transboundary Air Pollution (LRTAP) Gothenburg Protocol, which required them to reduce their emissions to the agreed ceiling, specified in the protocol, by 2010. Liechtenstein has also signed, but has not ratified, the protocol.


Both the NECD and the Gothenburg Protocol set reduction targets for SO2, NOx, NMVOCs and NH3 for the EEA-33 member countries. There are substantial differences in emission ceilings and, hence, emission reduction percentages for different countries, due to the different sensitivities of the ecosystems affected and the technical feasibility of making reductions.

Related policy documents



Methodology for indicator calculation

For air pollutants, data officially reported to the European Monitoring and Evaluation Programme (EMEP)/LRTAP Convention have been used. According to reporting requirements, emission figures for all pollutants are available from 1990, and for PM2.5, PM10 and total suspended particles (TSP) from 2000.

Methodology for gap filling

Where a complete time series of emission data has not been reported, 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 1990-2017 under the UNECE's Convention on LRTAP (EEA Technical Report No 8/2019).

Methodology references

  • EU emission inventory report European Union emission inventory report 1990-2017 under the UNECE Convention on Long-range Transboundary Air Pollution (LRTAP) , EEA Technical report No 8/2019.


Methodology uncertainty

Interpolation/extrapolation procedures are used to gap fill the underlying emission data set.

Data sets uncertainty

For the quantification of uncertainty, the EU LRTAP emissions inventory requires that Member States provide detailed information on uncertainties related to reported emissions data.

Rationale uncertainty

No uncertainty has been specified

Data sources

Other info

DPSIR: Pressure
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • TERM 003
Frequency of updates
Updates are scheduled once per year
EEA Contact Info


Geographic coverage

Temporal coverage