Specific air pollutant emissions

Assessment versions

Published (reviewed and quality assured)

• Specific air pollutant emissions (TERM 028) - Assessment published Jan 2011
• Specific air pollutant emissions (TERM 028) - Assessment published Sep 2010
• Specific air pollutant emissions (TERM 028) - Assessment published Apr 2009

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.

Scientific references:

• No rationale references available

Indicator definition

• 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.

Units

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

Context description

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).

Targets

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

Methodology

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. 

Methodology references

• 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.

Data specifications

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

Uncertainties

Methodology uncertainty

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.

Rationale uncertainty

No uncertainty has been specified