Indicator Assessment

Emissions of air pollutants from transport

Indicator Assessment
Prod-ID: IND-112-en
  Also known as: TERM 003
Published 12 Dec 2014 Last modified 11 May 2021
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The latest year’s available data show a continuation of the general trend for decreases in air pollutant emissions from transport: all transport-derived pollutants decreased between 2011 and 2012 (by 6 % in the case of NOx, 7 % for SOx, and by 6 % and 7 % in the case of PM10 and PM2.5, respectively). The latest data show that non-exhaust emissions are 46 % of the exhaust emissions of primary PM10 in 2012, and 31 % of the exhaust emissions of primary PM2.5.

Aviation is the only subsector where emissions have increased in the last year available, by 7 % for NH3 and by 9 % for SOx emissions. Aviation and shipping are the two sectors where increases in activity since 1990 have offset reductions elsewhere, in particular for SOx but also for NOx and PM. Road transport and aviation have also increased NH3 emissions significantly over the last two decades, but while road transport has recently reduced its emissions, aviation has not yet been able to do so.

In general terms, the transport sector achieved important reductions in the period 1990 through 2012: reductions in CO and non-methane volatile organic compounds (NMVOCs) (both 81 %), but also in NOx (33 %), SOx (26 %) and particulates (by 23 % in the case of PM2.5 and by 18 % for PM10).

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


Trend in emissions of air pollutants from transport


Significant 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 sectors are shown in the above figures. Emissions from all transport sectors have declined since 1990 despite the general increase in activity within the sector since this time. Across the EEA-33, transport emissions of NOwere reduced between 1990 and 2012 by 33 %, PM2.5 by 23 %, SOx by 26 %, CO by 81 % and NMVOCs by 81 %.

The scale of policy actions undertaken in Europe to specifically address issues concerning air pollution has increased over the past years. Local and regional air quality management plans including initiatives such as low-emission zones in cities or congestion charges are now undertaken in areas of high air pollution from transport. The different legal mechanisms for air quality management related to traffic comprise 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 emissions standards (like EURO 1-6) or by setting requirements of fuel quality.

Reductions achieved in the road transport sector are responsible for the vast majority of the overall reductions shown in Figure above for each pollutant. In contrast, international aviation and shipping (excepting SOx for the latter) are the only transport sub-sectors where emissions of each pollutant have actually increased since 1990. For example, NOx emissions from international aviation have almost doubled (+93%) since 1990, while NOx and NMVOCs from international shipping have both increased by around 30 %, and PM2.5 by 51 %. As emissions of pollutants such as NOx and SOx from land-based sources decreases, 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 19 % and 18 % of NOx and SOx emissions, respectively.

Transport is responsible for more than half of NOx emissions, and contributes significantly (around 15 % or more) to the total emissions of the other pollutants. Road transport in particular makes 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). While emissions of primary PM2.5 from road transport have declined since 1990 (by 44 %) the relative importance of the non-exhaust emissions has increased, as the introduction of vehicle particulate abatement technologies has reduced exhaust emissions. In 2012, the non-exhaust emissions of PM2.5 constituted 31 % of the emissions from the road transport sectors, compared to just 13 % in 1990 (for PM10 the contribution has increased from 21 % in 1990 to just below 46 % in 2012).

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