Exceedances of air quality objectives due to traffic

Indicator Assessment
Prod-ID: IND-106-en
Also known as: TERM 004
Created 11 Nov 2013 Published 15 Mar 2016 Last modified 15 Mar 2016, 03:33 PM
Topics: , ,
Achieving levels of good air quality in Europe is still a challenge, especially in urban areas with high volumes of traffic. Despite considerable improvements over recent decades, air pollution is still responsible for more than 400 000 premature deaths in Europe each year. It also continues to damage vegetation and ecosystems. Transport contributes significantly to the emissions of many air pollutants and the resulting poor air quality, particularly in urban areas with high traffic volumes. The annual EU limit value for NO 2 , one of the main air quality pollutants of concern and typically associated with vehicle emissions, was widely exceeded across Europe in 2013, with 93 % of all exceedances occurring at road‑side monitoring locations. In 2013, about 17 % of the EU‑28 urban population was exposed to PM 10 above the EU daily limit value. In 2013, transport also contributed to 13 % and 15 % of the total PM 10 and PM 2.5 primary emissions, respectively, in the EU Member States. Non-exhaust emissions are estimated to equal about 50 % of the exhaust emissions of primary PM 10  and about 22 % of those of primary PM 2.5 .

Key messages

  • Achieving levels of good air quality in Europe is still a challenge, especially in urban areas with high volumes of traffic.
  • Despite considerable improvements over recent decades, air pollution is still responsible for more than 400 000 premature deaths in Europe each year. It also continues to damage vegetation and ecosystems.
  • Transport contributes significantly to the emissions of many air pollutants and the resulting poor air quality, particularly in urban areas with high traffic volumes.
  • The annual EU limit value for NO2, one of the main air quality pollutants of concern and typically associated with vehicle emissions, was widely exceeded across Europe in 2013, with 93 % of all exceedances occurring at road‑side monitoring locations.
  • In 2013, about 17 % of the EU‑28 urban population was exposed to PM10 above the EU daily limit value. In 2013, transport also contributed to 13 % and 15 % of the total PM10 and PM2.5 primary emissions, respectively, in the EU Member States. Non-exhaust emissions are estimated to equal about 50 % of the exhaust emissions of primary PM10 and about 22 % of those of primary PM2.5.

Is the transport sector's contribution to air pollution being reduced?

Annual mean NO2 concentrations observed at traffic stations

Note: The figure shows the annual mean of nitrogen dioxide (NO2) observed at traffic stations in 2013.

Data source:
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Annual mean NO2 concentrations observed at background stations

Note: The figure shows the background concentrations of nitrogen dioxide (NO2) observed at background stations in 2013.

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Annual mean PM10 concentrations observed at traffic stations

Note: The figure shows the annual mean of particulate matter (PM10) observed at traffic stations in 2013. The two highest PM10 concentration classes (dark orange and light orange) correspond to the 2005 annual limit value (40 μg/m3) and to a statistically derived level (31 μg/m3) corresponding to the 2005 daily limit value. The lowest class corresponds to the WHO air quality guideline for PM10 of 20 μg/m3.

Data source:
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Annual mean PM10 concentrations observed at background stations

Note: The figure shows the background concentrations of PM10 observed at traffic stations in 2013. The two highest PM10 concentration classes (dark orange and light orange) correspond to the 2005 annual limit value (40 μg/m3) and to a statistically derived level (31 μg/m3) corresponding to the 2005 daily limit value. The lowest class corresponds to the WHO air quality guideline for PM10 of 20 μg/m3.

Data source:
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Annual mean PM2.5 concentrations observed at traffic stations

Note: The figure shows the annual mean concentrations of particulate matter (PM2.5) observed at traffic stations in 2013.

Data source:
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Annual mean PM2.5 concentrations observed at background stations

Note: The figure shows the annual mean concentrations of particulate matter (PM2.5) observed at background stations in 2013.

Data source:
Downloads and more info

Air quality in urban areas is significantly influenced by local traffic. While considerable progress has been made over the past twenty years in improving urban air quality, a number of issues remain. Despite considerable improvements, air pollution is still responsible for more than 400 000 premature deaths in Europe each year. It also continues to damage vegetation and ecosystems. Since the late 1990s, concentrations of nitrogen dioxide (NO2) and particulate matter (PM10) in urban areas have not been declining in line with emissions trends. Although emissions from transport have been declining, there are still many areas where limit values for NO2 and PM10 are exceeded across Europe, mainly due to road traffic.

For example, the annual EU limit value for NO2, one of the main air quality pollutants of concern and typically associated with vehicle emissions, was widely exceeded across Europe in 2013, with 93 % of all exceedances occurring at road‑side monitoring locations. Also, in 2013, about 17 % of the EU‑28 urban population was exposed to PM10 above the EU daily limit value.

The disparity between trends in emissions estimates and ground level concentration of these pollutants can at least partly be explained by the difference between the laboratory and the real‑world emissions performance of vehicles. However, there are further specific features of the traffic and urban environment that add to this disparity. In addition to this, an increase in NO2 emitted directly into the air from diesel vehicles (the proportion of NO2 in the nitrogen oxides (NOx) emissions of a diesel vehicle is far higher than the proportion of NO2 in the NOx emissions of a conventional-petrol vehicle) has been reported. Mainly due to the increasing number of diesel vehicles, some cities in Europe showed an increase in concentrations of NO2 measured close to traffic.

Moreover, vehicle composition in urban areas is generally different to the national composition. Actions to improve air quality need to take account of the local composition to ensure targeted measures are implemented. For example, buses, mopeds and motorcycles make up a higher proportion of vehicle composition in urban areas than they do nationally. Buses can emit high levels of NOx and PM unless measures are taken that ensure that they meet strict emission standards. Mopeds and motorcycles are high emitters of carbon monoxide (CO) and volatile organic compounds (VOC), particularly older models.

In addition, 'slow, stop and start' congested urban traffic conditions and frequent short journeys can result in higher emissions per kilometre compared to free-flowing longer journeys. This is a consequence of increased cold engine operation, higher fuel consumption and less efficient performance of exhaust emission abatement systems. Measures that reduce traffic congestion may therefore benefit air quality in the immediate area, although the full impacts need to be assessed over a wider area to ensure that traffic and emissions are not simply moved elsewhere.

Other characteristics of the urban environment can increase the impact of traffic emissions on air quality. For example, the presence of high buildings on either side of the road, common in many city centres, creates a 'street canyon', which reduces the dispersion of the emitted pollutants from traffic sources and can lead to significantly higher concentrations locally.

The monitoring data reported by the countries (Air Quality e-Reporting Database (http://www.eea.europa.eu/data-and-maps/data/aqereporting)) provide the basis for estimating the exposure of the urban European population to exceedances of the most stringent European air quality standards and WHO guidelines. The exposure is estimated based upon measured concentrations at all urban and suburban background monitoring stations for most of the urban population, and at traffic stations for populations living within 100 m of major roads. The methodology is described by the EEA (Exceedance of air quality limit values in urban areas (Indicator CSI 004)).

Indicator specification and metadata

Indicator definition

This indicator compares concentrations of pollutants at background stations to those at traffic stations. This comparison provides an estimate of the increased levels of air pollution that the population is exposed to in areas with increased road traffic. It also provides a measure of the impact of the technical and non-technical measures adopted to reduce the contribution of the road transport sector to the observed concentrations. 

The indicator makes use of the data submitted to Airbase. Data permitting, a pan-European coverage is attempted and the indicator focuses on selected station pairs (traffic and urban background stations) from capital cities across Europe. Where data in capital cities is not available the next largest city is chosen.

Units

The units used in this indicator are the average yearly, daily and weekly variations of the concentrations at traffic and urban background stations, measured in micrograms per cubic metre (mg/m3).


Policy context and targets

Context description

This indicator provides information relevant for current European air quality legislation related to the setting of national emissions targets (National Emission Ceiling Directive 2001/81/EC), the reduction of transport related emissions (discussed in detail in TERM 34) and the protection of human health from harmful air pollutant levels (Directives 1999/30/EC for sulphur dioxide, nitrogen dioxide and particulate matter and 2002/3/EC for ozone, both discussed in detail in CSI 004). The Directive on ambient air quality and cleaner air for Europe (Directive 2008/50/EC) also sets target and limit values for PM2.5 (particulate matter that passes through a size-selective inlet with a 50 % efficiency cut-off at 2.5 micrometers aerodynamic diameter), since 2010.

Targets

EU limit values on concentrations of nitrogen dioxide in ambient air

Both limit values had to be met by 1 January 2010:

  • In the Council Directive 1999/30/EC (section 1 of Annex II), an annual mean limit value for nitrogen dioxide of 40 mg NO2/m3 has been set for the protection of human health.
  • An hourly limit value of 200 mg NO2/m3, not to be exceeded more than 18 times per calendar year, has also been set.

 

EU limit values on concentrations of PM10 in ambient air

Both limit values had to be met by 1 January 2005:

  • a limit value for PM10 of 50 mg/m3 (24 hour average, i.e. daily), not to be exceeded more than 35 times per calendar year, has been set for the protection of human health in Council Directive 1999/30/EC (Annex III).
  • a limit value of 40 mg/m3, as annual average, has also been set.

 

EU limit values on concentrations of other pollutants:

- sulphur dioxide

Two limit values have been set for the protection of human health. Both limit values had to be met by 1 January 2005

  • a limit value of 125 mg SO2/m3, as a daily average not to be exceeded more than three times a calendar year, has been set for the protection of human health in the adopted Daughter 1999/30/EC, Section I of Annex I.
  • an hourly limit value for the protection of human health has been set at 350 mg

 

- ozone 

A combined ozone and acidification abatement strategy has been developed by the European Commission, resulting in a new Ozone Daughter Directive (2002/3/EC) and a National Emission Ceiling Directive (2001/81/EC). In this legislation, target values for ozone levels and for precursor emissions have been set.

  • The Ozone Daughter Directive sets a target value for the protection of human health of 120 mg O3/m3, as a maximum daily 8 hour mean, not to be exceeded more than 25 days per calendar year, averaged over three years. This target should be met in 2010.
  • The Ozone Daughter Directive has also set a long-term objective of 120 mg O3/m3, as a maximum daily 8 hour average not to be exceeded on any day within a calendar year.

Related policy documents

  • COM(2001) 245 final. The Clean Air for Europe (CAFE).
    The Clean Air for Europe (CAFE) Programme: Towards a Thematic Strategy for Air Quality COM(2001) 245 final
  • Council Directive 96/62/EC of 27 September 1996
    Council Directive 96/62/EC of 27 September 1996 on ambient air quality assessment and management.
  • Council Directive 1999/30/EC of 22 April 1999
    Council Directive 1999/30/EC of 22 April 1999 Relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air
  • Directive 2001/81/EC, national emission ceilings
    Directive 2001/81/EC, on nation al emissions ceilings (NECD) for certain atmospheric pollutants. Emission reduction targets for the new EU10 Member States have been specified in the Treaty of Accession to the European Union 2003  [The Treaty of Accession 2003 of the Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Malta, Poland, Slovenia and Slovakia. AA2003/ACT/Annex II/en 2072] in order that they can comply with the NECD.
  • Directive 2002/3/ EC...ozone in ambient air
    Directive 2002/3/ EC of the European Parliament and of the Council of 12 February 2002 relating to ozone in ambient air
  • Directive 2008/50/EC, air quality
    Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe.

Methodology

Methodology for indicator calculation

Concentrations:
Data submitted to Airbase has been used. The average diurnal variation was obtained by averaging each hour of the hourly data available at the selected measurement station. Average weekly variation was obtained by averaging the daily average for each day of the week (hourly or average daily data were used, depending on data availability) at the selected measurement station. Average yearly data were obtained from average hourly or average daily data, whichever were available at the selected measurement station (see data availability table for details). For all of the above, data gaps were not filled in.

Methodology for gap filling

No gap-filling is applied for this indicator, however, the databases and spreadsheets used for the production of the indicator contain gap-filled values.

Methodology references

Uncertainties

Methodology uncertainty

Air quality data are officially submitted. It is assumed that data have been validated by the national data supplier. Station characteristics and representativeness are often insufficiently documented. The data are thought to be representative for the urban population in each city. Locally (at the city level) the indicator is subject to year-on-year variations due to meteorological variability.

Data sets uncertainty

  • Strengths and weaknesses (at data level): data officially reported by the countries to Airbase are used, however, the data reported across countries vary in quantity. Also, the station characterisation (urban background or traffic) is difficult to compare across countries. 
  • Reliability, accuracy, robustness, uncertainty (at data level): Uncertainties are discussed separately for each graph. The data quality cannot be commented upon, since the data are reported by the individual countries, but data availability is sometimes low and does not allow for robust conclusions/intercomparisons (see data availability table for details). The main problem is the lack of data and not the actual quality of the data available.

Rationale uncertainty

No uncertainty has been specified

Data sources

Generic metadata

Topics:

Transport Transport (Primary topic)

Air pollution Air pollution

Tags:
transport | air pollution
DPSIR: State
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • TERM 004
Dynamic
Temporal coverage:
2013
Geographic coverage:
Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, United Kingdom

Contacts and ownership

EEA Contact Info

Cinzia Pastorello

EEA Management Plan

2015 1.1.2 (note: EEA internal system)

Dates

Frequency of updates

Updates are scheduled once per year
Filed under: ,
European Environment Agency (EEA)
Kongens Nytorv 6
1050 Copenhagen K
Denmark
Phone: +45 3336 7100