Specific air pollutant emissions
Published (reviewed and quality assured)
Justification for indicator selection
Transport is a major contributor to air pollution. In 2010, road transport alone accounts for 42, 16, 15 and 29 % of total NOx, VOC, PM and CO emissions respectively (see TERM 03 - Transport emissions of air pollutants). Advanced after-treatment technology introduced by the automobile industry due to tighter emission limits can therefore result in considerable reduction in specific pollutant emissions.
The specific emissions of air pollutants of passenger and freight transport are determined by the fleet composition (number and type of vehicles), vehicle utilisation (occupancy rates and load factors) and driving characteristics (speeds, distances). This indicator has been selected to monitor the impact of the stricter emission standards on the specific emissions of air pollutants of the various passenger and freight transport modes.
- No rationale references available
- Specific emissions are defined as emissions of pollutants per transport unit (passenger-km or tonne-km), specified by mode (road, rail, inland, maritime, air). The pollutants considered include NOx, VOC, PM and CO.
- For passenger transport, specific emissions are expressed in grams of pollutant (NOx, VOC, PM, CO) per passenger-kilometre. For freight transport, specific emissions are expressed in grams of pollutant (NOx, VOC, PM, CO) per tonne-kilometre.
For passenger transport, specific emissions are expressed in grams of pollutant (NOx, VOC, PM, CO) per passenger-kilometer.
For freight transport, specific emissions are expressed in grams of pollutant (NOx, VOC, PM, CO) per tonne-kilometer.
Policy context and targets
Since specific emissions are expressed per transport unit, occupancy rates and load factors have a considerable effect on specific emissions produced from passenger and freight transport respectively. Reduction of specific emissions can be achieved by increasing occupancy rates and load factors and/or by decreasing the emissions per vehicle-km (e.g. by setting stricter emission standards and introducing more energy efficient technologies such as hybrid, plug-in hybrids, electric vehicles, etc).
No explicit targets exist at European level directly addressing specific emissions. Policy objectives are rather set with respect to the environmental performance of the fleet (see also TERM 34).
Related policy documents
No related policy documents have been specified
Key policy question
Is the reduction in specific emissions consistent with the stricter emission standards?
Methodology for indicator calculation
For passenger transport, the specific emissions are calculated by dividing the pollutant emissions of each mode (i.e. road, rail, maritime and air transport) by the respective passenger-kilometres.
For freight transport, the specific emissions are calculated by dividing the pollutant emissions of each mode (i.e. road, rail, inland shipping and maritime transport) by the respective tonne-kilometres.
Methodology for gap filling
Passenger- and tonne-kilometres and emissions of NOx, VOC, PM and CO are modelled and therefore no gap filling is necessary.
- TREMOVE documentation Specific NOx, VOC, PM and CO emissions data for road, rail and inland shipping transport, 1995-2010 are modelled data from TREMOVE v3.3.1.
EEA data references
- No datasets have been specified here.
External data references
- NOx, VOC, PM and CO emissions, passenger-km and tonne-km from road, rail and inland shipping
- NOx, VOC, PM and CO emissions, passenger-km and tonne-km from air and maritime transport
Data sources in latest figures
Road transport emissions calculated with TREMOVE v3.3.1 are generally underestimated compared to CLRTAP submissions (by about 10 % for CO and NOx and 30 % for PM and CO).
Data sets uncertainty
Since the data on pollutant emissions, passenger-km and tonne-km are modelled rather than measured, the data must be treated as estimates. The uncertainty of emissions and the uncertainty of passenger-km and tonne-km vary significantly among different countries depending on the underlying statistical data used for each country. As an example, the calculated uncertainty (given as the coefficient of variance) for the UK is 69% for the CO emissions, 37% for VOC, 25% for PM, 19% for NOx and 2% for the vehicle-kilometres.
No uncertainty has been specified
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.
Responsibility and ownership
EEA Contact InfoCinzia Pastorello
Frequency of updates
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)