The indicator measure the relative change (in %) in the emissions of different pollutants (CO, NOx, NMVOC, SOx, NH3, CH4, N2O, PM10, PM2.5) in the transport sector as a whole and for different subsectors. Relative variations were indexed with respect to year 1990 for all pollutants with the exception of PM that was indexed from year 2000.
For CO, NOx, NMVOC, SOx, NH3, PM10 and PM2.5, data officially reported to the European Monitoring and Evaluation Programme (EMEP)/LRTAP Convention were used. For CH4 and N2O data officially reported under the United Nations Framework Convention on Climate Change (UNFCCC) and also under the Kyoto Protocol (KP) were used.
Where a complete time series of emission data has not been reported for CO, NOx, NMVOC, SOx, NH3, PM10 and PM2.5, 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 1990-2019 under the UNECE's Convention on LRTAP (EEA Technical Report No 5/2021). Similarly, for CH4 and N2O additional information on the gap-filling procedure can be found in the Annual European Union greenhouse gas inventory 1990–2020 and inventory report 2022 Submission to the UNFCCC Secretariat.
The transport sector emits a number of pollutants, which puts significant pressures on the environment and air quality in many parts of Europe. This issue is extensively addressed by policy and this has led to notable improvements in specific sectors. The Air Quality Directives sets limits or target values for concentrations of pollutants in the ambient air, while the NEC Directive sets emission reduction commitments on total emissions (i.e. national totals) for five air pollutants (NOx, SO2, NMVOC, NH3 and PM2.5). Emissions from the road sector are further regulated by vehicle emissions standards and fuel quality requirements. A new emission standard, i.e. Euro 7, for the road sector has just been recently proposed.
Transport emissions of ammonia (NH3) and nitrous oxide (N2O) are increasing and are of concern: NH3 emitted within the cities have a very high impact on air quality; N2O, beside a powerful greenhouse gas, is also currently considered a dominant ozone depleting substance. Both these pollutants are currently unregulated.
For CO, NOx, NMVOC, SOx, NH3, PM10 and PM2.5, data officially reported to the European Monitoring and Evaluation Programme (EMEP)/LRTAP Convention were used. For CH4 and N2O data officially reported under the United Nations Framework Convention on Climate Change (UNFCCC) and also under the Kyoto Protocol (KP) were used.
Where a complete time series of emission data has not been reported for CO, NOx, NMVOC, SOx, NH3, PM10 and PM2.5, 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 1990-2019 under the UNECE's Convention on LRTAP (EEA Technical Report No 5/2021). Similarly, for CH4 and N2O additional information on the gap-filling procedure can be found in the Annual European Union greenhouse gas inventory 1990–2020 and inventory report 2022 Submission to the UNFCCC Secretariat.