Indicator Assessment

Emissions of air pollutants from transport

Indicator Assessment
Prod-ID: IND-112-en
  Also known as: TERM 003
Created 13 Aug 2019 Published 17 Dec 2019 Last modified 17 Dec 2019
9 min read
  • Between 1990 and 2017, the transport sector significantly reduced emissions of the following air pollutants: carbon monoxide and non-methane volatile organic compounds (both by around 87 %), sulphur oxides (66 %) and nitrogen oxides (40 %). Since 2000, a reduction in particulate matter emissions (44 % for PM2.5 and 35 % for PM10) has occurred.
  • Emissions from road transport have declined less than was anticipated over the last two decades and continue to decrease (except emissions of sulphur oxides in recent years). In 2017, emissions were lower than in the previous year: emissions of nitrogen oxides decreased by 3 % and those of carbon monoxide by 3.2 %, those of PM10 and PM2.5 decreased by 1.4 % and 3.6 %, respectively. Emissions of sulphur oxides increased by 2.7 % in 2017, compared with 2016, but it is still less than 1 % of what have been emitted in 1990.
  • Emissions of air pollutants have decreased for all transport modes since 1990, except for shipping, for which nitrogen oxide emissions have increased, and aviation, for which emissions of all pollutants (except non-methane volatile organic compounds) have increased.

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


Trends 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 Figs 1 and 2. Emissions from all transport types have declined since 1990, despite the general increase in activity within the sector. Across the EEA-33 (the 28 EU Member States plus Iceland, Lichtenstein, Norway, Switzerland and Turkey) between 1990 and 2017, emissions of nitrogen oxides (NOx) from transport decreased by 40 %, those of sulphur oxides (SOx) decreased by 66 %, and those of both carbon monoxide (CO) and non-methane volatile organic compounds (NMVOCs) decreased by 87 %. Between 2000 and 2017, emissions of particulate matter with a diameter of 2.5 µm or less (PM2.5) decreased by 44 %.

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 to reducing air quality. Local and regional air quality management plans  including initiatives such as low-emission zones in cities and congestion charges — are now undertaken in many areas where the level of 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 emissions standards (such as Euro emissions standards 1-6) or by setting requirements for fuel quality.

Reductions in emissions from the road transport sector account for the majority of the overall reductions for each pollutant, as shown in Figs 1 and 2. Since 1990, CO emissions from road transport decreased by 88 %, emissions of NMVOCs decreased by 89 %, emissions of NOx decreased by 60 % and emissions of SOx decreased by 99 %. In contrast, since 1990, international and domestic aviation (NOx, SOx, PM2.5 and PM10 for both and CO emissions for international aviation only) and international shipping (CO, NOx and NMVOCs) have been the transport sub-sectors for which emissions of the indicated pollutants have actually increased. Emissions of ammonia (NH3) from road transport have also increased, although they account for only a very small fraction of total NH3 emissions. Emissions of NOx from international aviation have more than doubled (increase of 171 %) since 1990, while NOx, CO and NMVOC emissions from international shipping have increased by around 26 %, 25 % and 20 %, respectively. Since 2000, PM2.5 and PM10 emissions have decreased for all transport types, except international aviation, for which PM2.5 and PM10 emissions have increased by 30 % and 29 %, respectively. As emissions of pollutants such as NOx and SOx from land-based sources decrease, there is growing awareness of the increasingly important contribution that the national and international shipping sectors make to Europe's air quality, with these sectors now being responsible for 23 % and 12 % of all NOx and SOx emissions, respectively.

Transport is responsible for more than two thirds of all NOx emissions and accounts for a significant proportion (around 10 % or more) of the total emissions of other pollutants. Road transport, in particular, continues to account for a significant proportion of emissions of all the main air pollutants (with the exception of SOx). It is widely accepted that 'real-world emissions' of nitrogen oxides, particularly from diesel passenger cars and vans, generally exceed the permitted Euro emissions standard, which defines the acceptable limits for exhaust emissions of new vehicles sold in EU Member States. While emissions from road transport are mostly exhaust emissions arising from fuel combustion, non-exhaust releases contribute to both NMVOC (from fuel evaporation) and primary PM (from tyre - and brake-wear, and road abrasion) emissions. Emissions of primary PM2.5 from road transport have increased by 22 % since 2000 and the relative importance of non-exhaust emissions has increased as a result of the introduction of particulate abatement technologies in vehicles, which has reduced exhaust emissions. In 2017, the non-exhaust emissions of PM2.5 accounted for 46 % of emissions from the road transport sector, compared with 18 % in 2000 (for PM10, the contribution increased from 32 % in 2000 to 63 % in 2017).

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