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Transport emissions of air pollutants

Indicator Specification Created 04 Jan 2011 Published 12 Jan 2011 Last modified 04 Sep 2015, 06:59 PM
Topics: , ,
Indicator codes: TERM 003

Assessment versions

Published (reviewed and quality assured)


Justification for indicator selection

This indicator analyses the transport emissions of CO,  NOx, NMVOCs, PM10, PM2.5 and SOx over time. The pollutants can be grouped into acidifying substances, particulates and ozone precursors. Transport contributes significantly to emissions of NOx, NMVOC, PM and CO. NOx contributes to acidification, formation of ground level ozone and particulate formation.

Acidifying substances: Acidification of soils and waters is caused by emissions of nitrogen oxides (NOx), sulphur oxides (SOx) and ammonia (NH3) into the atmosphere, and their subsequent chemical reactions and deposition on ecosystems and materials. Deposition of acidifying substances causes damages to ecosystems, buildings and materials (corrosion).

Particulate Formation: Airborne particulate matter (PM) has adverse effects on human health and can be responsible and/or contribute to a number of respiratory problems. In this assessment, ‘particulate formation’ refers to primary emissions of PM10, PM 2.5 and emissions of precursors (NOx, SOx and NH3) leading to the secondary physico-chemical production of inorganic particulate matter in the atmosphere (secondary PM). A large fraction of the urban population is exposed to levels of fine particulate matter in excess of air quality limit values set for the protection of human health.

Ozone precursors: Emissions of non-methane volatile organic compounds (NMVOC), nitrogen oxides (NOx), carbon monoxide (CO) and methane (CH4) contribute to the formation of ground-level (tropospheric) ozone which has adverse effects on human health and ecosystems.


Scientific references

  • No rationale references available

Indicator definition

The indicator is based on the emission trend assessment of CO, NOx, NMVOCs, SOx and primary particulates. 


Emissions are expressed as percentage over the 1990 levels.

Policy context and targets

Context description

Directive 2008/50/EC (EC, 2008) sets LVs for the atmospheric concentrations of main pollutants, including sulphur dioxide (SO2), nitrogen dioxide (NO2), airborne particulate matter (PM10, PM2.5), lead, carbon monoxide (CO), benzene, and ozone (O3) for EU Member States. These limits are related to transport implicitly, but the introduction of progressively stricter Euro emission 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 further reduce air pollutant emissions.
Iceland, Liechtenstein, Norway, Switzerland and Turkey are not members of the European Union and hence have no emission ceilings set under the National Emission Ceilings Directive (NECD) 2001/81/EC. As well as most of the EU Member States, Norway and Switzerland have ratified the 1999 United Nations Economic Commission for Europe Convention on Long-range Transboundary Air Pollution (UNECE Trend in emissions of air pollutants from transport in EEA-33 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 Gothenburg protocol set reductions targets for sulphur dioxide, nitrogen oxides and non-methane volatile organic compounds and ammonia for the 33 EEA member countries. There are substantial differences in emission ceilings, and hence emission reduction percentages for different countries, due to the different sensitivities of the affected ecosystems and technical feasibility for reductions.

Related policy documents

  • 1999 Protocol to Abate Acidification, Eutrophication and Ground-level Ozone
    Convention on Long-range Transboundary Air Pollution 1999 Protocol to Abate Acidification, Eutrophication and Ground-level Ozone, amended on 4 May 2012.
  • Council Directive 96/61/EC (IPPC)
    Council Directive 96/61/EC of 24 September 1996 concerning Integrated Pollution Prevention and Control (IPPC). Official Journal L 257.
  • Directive 98/70/EC, quality of petrol and diesel fuels
    Directive 98/70/EC of the European Parliament and of the Council of 13 October 1998 relating to the quality of petrol and diesel fuels and amending Directive 93/12/EEC
  • Directive 2001/80/EC, large combustion plants
    Directive 2001/80/EC of the European Parliament and of the Council of 23 October 2001 on the limitation of emissions of certain pollutants into the air from large combustion plants
  • Directive 2001/81/EC, national emission ceilings
    Directive 2001/81/EC, on nation al emissions ceilings (NECD) for certain atmospheric pollutants. Emission reduction targets for the new EU10 Member States have been specified in the Treaty of Accession to the European Union 2003  [The Treaty of Accession 2003 of the Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Malta, Poland, Slovenia and Slovakia. AA2003/ACT/Annex II/en 2072] in order that they can comply with the NECD.


Methodology for indicator calculation

For air pollutants officially reported data to EMEP/LRTAP has been used. Please refer to indicators CSI002 and CSI003

Methodology for gap filling

Where a complete time series of emissions data has not been reported, data has been gap-filled according to EEA ETC/ACC methodologies. Details of the gap-filling procedure for the air pollutant data set are described in the European Union emission inventory report 1990–2008 under the UNECE Convention on Long-range Transboundary Air Pollution (LRTAP) (EEA Technical Report No 7/2010).

Methodology references

No methodology references available.

Data specifications

EEA data references

  • No datasets have been specified here.

Data sources in latest figures


Methodology uncertainty

Interpolation/extrapolation procedures are used for gap-filling of the underlying emissions dataset.

Data sets uncertainty

A quantification of uncertainty in the European Union LRTAP emission inventory requires the provision of detailed underpinning information on emission uncertainties from Member States.

Rationale uncertainty

No uncertainty has been specified

Further work

Short term work

Work specified here requires to be completed within 1 year from now.

Long term work

Work specified here will require more than 1 year (from now) to be completed.

General metadata

Responsibility and ownership

EEA Contact Info

Cinzia Pastorello


European Environment Agency (EEA)


Indicator code
TERM 003
Version id: 2
Primary theme: Transport Transport


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Frequency of updates

Updates are scheduled once per year


DPSIR: Pressure
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)

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