Emissions of air pollutants from transport

Indicator Specification
Indicator codes: TERM 003
Created 04 Jan 2011 Published 12 Jan 2011 Last modified 04 Oct 2018
6 min read
Topics: , ,
This indicator is based on the emissions trend assessment of CO, NO x , NMVOCs, SO x and primary particulates. 

Assessment versions

Published (reviewed and quality assured)


Justification for indicator selection

This indicator analyses the emissions of CO, NOx, NMVOCs, PM10, PM2.5 and SOx over time from transport. These pollutants can be grouped into acidifying substances, particulates and ozone precursors. Transport contributes significantly to emissions of NOx, NMVOCs, 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. The deposition of acidifying substances causes damage to ecosystems, buildings and materials (corrosion).

Particulate Formation: Airborne particulate matter (PM) has adverse effects on human health and can be responsible for and/or contribute to a number of respiratory problems. In this assessment, 'particulate formation' refers to primary emissions of PM10, PM2.5 and emissions of precursors (NOx, SOx and NH3), which lead 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 (NMVOCs), 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

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


Emissions are expressed as the percentage over 1990 levels (PM as percentage over 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 particulate matter (PM10 and 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, in order 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 European Union and hence have no emission ceilings set under the revised National Emission Ceilings Directive (NECD) 2016/2284/EU. 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 the Gothenburg protocol set reduction targets for sulphur dioxide, nitrogen oxides, non-methane volatile organic compounds and ammonia 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

Key policy question

Are emissions of acidifying substances, particulates and ozone precursors from transport decreasing?


Methodology for indicator calculation

For air pollutants, officially reported data to the European Monitoring and Evaluation Programme (EMEP)/LRTAP have been used. According to reporting requirements, emission figures for all pollutants are available from 1990, and for PM2.5, PM10 and 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 EEA's European Topic Centre for Air and Climate Change (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

  • EC emission inventory report European Community emission inventory report 1990-2015 under the UNECE Convention on Long-range Transboundary Air Pollution (LRTAP) , EEA Technical report No 9/2017.

Data specifications

EEA data references

Data sources in latest figures


Methodology uncertainty

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

Data sets uncertainty

The quantification of uncertainty in the European Union LRTAP emissions inventory requires that Member States provide detailed underpinning information on emissions uncertainties.

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

Federico Antognazza


European Environment Agency (EEA)


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

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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Data used

Latest figures and vizualizations

Relevant policy documents

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