Indicator Assessment
Specific air pollutant emissions
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- The specific emissions of air pollutants from passenger and freight transport decreased during the time period 1995-2009 for the majority of transport modes and especially for passenger transport.
- The highest reduction of specific emissions can be observed in the road sector, following the implementation of increasingly strict emission standards.
- Railway and aviation have also recorded reductions, while maritime passenger and freight transport emissions remained approximately constant over the same time period.
- Rail and water transport are still relatively clean forms of transport - compared to road and air transport - but without any regulations on their emissions, these modes might lose this leading position.
Specific emissions of NOx per passenger-km or tonne-km and per mode of transport, 1995-2009
Note: The graph shows development of specific NOx emissions, defined as emissions of NOx per transport unit (passenger-km or tonne-km), by transport mode (road, rail, maritime, inland shipping, air) in 1995 and 2009.
Specific emissions of VOC per passenger-km or tonne-km and per mode of transport, 1995-2009
Note: The graph shows development of specific VOC emissions, defined as emissions of VOC per transport unit (passenger-km or tonne-km), by transport mode (road, rail, maritime, inland shipping, air) in 1995 and 2009.
Specific emissions of PM per passenger-km or tonne-km and per mode of transport, 1995-2009
Note: The graph shows development of specific PM emissions, defined as emissions of PM per transport unit (passenger-km or tonne-km), by transport mode (road, rail, maritime, inland shipping, air) in 1995 and 2009.
Specific emissions of CO per passenger-km or tonne-km and per mode of transport, 1995-2009
Note: The graph shows development of specific CO emissions, defined as emissions of CO per transport unit (passenger-km or tonne-km), by transport mode (road, rail, maritime, inland shipping, air) in 1995 and 2009.
- Road remains by far the most polluting passenger transport mode with respect to CO and VOC specific emissions, even though it recorded the highest decreases (about 85 % for both CO and VOC emissions) from 1995 to 2009 compared to the other modes. As regards NOx and PM specific emissions, road passenger transport specific emissions are comparable with those of air and rail transport. Road is also the most polluting freight transport mode for all pollutants (with the exception of PM), although the specific emissions decreased from 42 % (NOx) to 72 % (PM) over the 1995 to 2009 period.
- Rail is generally the cleanest mode of transport for most pollutants. Specific NOx and PM emissions of rail transport have decreased considerably from 1995 to 2009, mainly due to the trend towards electric powered trains, especially for passenger traffic. Specific emissions from trains depend critically on the technical level and the method of energy production used. The emission factors for electricity production represent the airborne pollutants incurred during the whole production and supply process from fuel extraction to electricity transport to the sub-stations feeding the railway network. This indicates that the focus in the future should be in controlling emissions from power generation, along with implementing the engine economy and emission control technology, which has already advanced.
- Maritime shipping is one of the cleanest mode of freight transport, except for PM and specific sulphur oxide (SOx) emissions, which are the highest for shipping (and aviation), mainly due to the high sulphur content of bunker fuels. However, maritime shipping remains by far the most polluting passenger transport mode with regard to the specific NOx and PM emissions. The emissions generated by the maritime fleet are largely dependent on the quantity of fuel consumed; however, there are several factors besides fuel consumption, which influence the emissions generated. These include the fuel quality and the engine type. In particular, SOx and PM emissions are influenced by the quantity of sulphur within the fuel. In the future, emission reductions are expected from waterborne transport, mainly as a result of improved fuel quality and engine technology. EU legislation (Directive 2005/33/EC) setting more stringent limits for sulphur content in fuel oils will greatly contribute to the expected emission reductions. In addition to this, Commission Recommendation 2006/339/EC aims at promoting of shore-side electricity for use by ships at berth in Community ports.
- Specific emissions of CO and VOC from aviation are generally low, being comparable to those of maritime shipping. The International Civil Aviation Organization (ICAO) has established aircraft engine emission standards for NOx, which resulted in 30 % reductions achieved from 1995 to 2009. Despite this reduction, NOx specific emissions are still 40 to 60 % higher compared to road and rail respectively.
- It should be noted that the significant reductions in the emissions of all pollutants from road transport are mainly attributed to technological improvements and policy measures resulting from the strict emission standards imposed. On the other hand, the emissions from the other modes of transport are not subject to any emission control regulations, which would result in emission reductions similar to those from road transport.
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.
The pollutant emissions for the remaining modes of transport (i.e. rail, inland shipping, maritime and air transport) are calculated using Tier 1 emission factors from the EMEP/EEA air pollutant emission inventory guidebook.
Activity data for inland shipping rail and maritime transport are extracted from PRIMES, Eurostat.
For air transport, the number of total LTOs (from EUROSTAT-avia_tf_aca) is used to calculate the pollutant emissions.
For the calculation of emissions from electric trains, the relevant emission factor from electricity generation (in grams of pollutant per kWh of energy produced) was used. To this aim, the total emissions of each pollutant (data from the EU submission to CLRTAP), were divided by the total electricity production in the European Union (data from EUROSTAT).
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
- EC4MACS documentation Documents / Methodologies
- EMEP/EEA air pollutant emission inventory guidebook (2013) Technical report No 12/2013
Uncertainties
Methodology uncertainty
COPERT 4 is used for road transport emissions calculations in EC4MACS, whereas the Tier 1 method of the EMEP/EEA air pollutant emission inventory guidebook is used for non-road transport modes.
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
Rationale uncertainty
No uncertainty has been specified
Data sources
-
EC4MACS model
provided by The Laboratory for Thermodynamics of the Aristoteles University of Thessaloniki (LAT/AuTh) -
Railway transport measurement
provided by Statistical Office of the European Union (Eurostat) -
Inland waterways transport
provided by Statistical Office of the European Union (Eurostat) -
Railway transport - Total annual passenger transport
provided by Statistical Office of the European Union (Eurostat)
Other info
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
- TERM 028
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For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/specific-air-pollutant-emissions/specific-air-pollutant-emissions-assessment-2 or scan the QR code.
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