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Indicator Assessment

Exceedances of air quality limit values due to traffic

Indicator Assessment
Prod-ID: IND-106-en
  Also known as: TERM 004
Published 17 Dec 2019 Last modified 17 Dec 2019
5 min read
    • The annual EU limit value for nitrogen dioxide — one of the main air quality pollutants of concern, which is typically associated with vehicle emissions — was widely exceeded across Europe in 2017. Some 86 % of these exceedances were detected at roadside monitoring locations. 
    • The EU limit values for the two categories of particulate matter (PM10 and PM2.5) were also widely exceeded in 2017. For PM2.5, the percentage of exceedances recorded at traffic stations was very similar to that recorded at background stations. For PM10, a higher percentage of exceedances was recorded at background stations than at traffic stations. This indicates the importance of other emission sources for these pollutants, such as commercial and institutional buildings, household heating, etc.

Annual mean NO2 concentrations observed at traffic stations, 2017

Note: The figure shows the annual mean concentrations of nitrogen dioxide (NO2) observed at traffic stations in 2017.

Data source:

Annual mean NO2 concentrations observed at background stations, 2017

Note: The figure shows the annual mean concentrations of nitrogen dioxide (NO2) observed at background stations in 2017.

Data source:

Percentile 90.4 of daily mean PM10 concentrations observed at traffic stations, 2017

Note: The map shows the Percentile 90.4 of daily mean PM10 concentrations at traffic stations. This represents the 36th highest value in a complete series. It is related to the PM10 daily limit value, which allows 35 exceedances of the 50 µg/m3 threshold over a 1-year period. Dots in the last two colour categories indicate stations with concentrations above this daily limit value. Only stations for which more than 75 % of data are valid have been included in the map.

Data source:

Percentile 90.4 of daily mean PM10 concentrations observed at background stations, 2017

Note: The map shows the Percentile 90.4 of daily mean PM10 concentrations at background stations. This represents the 36th highest value in a complete series. It is related to the PM10 daily limit value, which allows 35 exceedances of the 50 μg/m3 threshold over a 1-year period. Dots in the last two colour categories indicate stations with exceedances of this daily limit value. Only stations for which more than 75 % of data are valid have been included in the map.

Data source:

Annual mean PM2.5 concentrations observed at traffic stations, 2017

Note: The figure shows the annual mean concentrations of particulate matter (PM2.5) observed at traffic stations in 2017.

Data source:

Annual mean PM2.5 concentrations observed at background stations, 2017

Note: The figure shows the annual mean concentrations of particulate matter (PM2.5) observed at background stations in 2017.

Data source:

Figs 1 to 6 show the air quality situation in 2017 at monitoring stations across Europe for three main pollutants related to road transport, i.e. nitrogen dioxide (NO2), particulate matter with a diameter of 10 μm or less (PM10) and particulate matter with a diameter of 2.5 μm or less (PM2.5). For each pollutant, measurements taken at two different types of location are shown. The first map shows traffic air quality monitoring stations, which are located in close proximity to major roads and affected predominantly by traffic sources. The second map shows background stations, which are located away from dominant single sources, so that the pollution levels recorded are representative of the average exposure of the general population.

For NO2, 10 % of reporting stations recorded concentrations above the annual limit value in 2017. The highest concentrations, as well as 86 % of all concentrations recorded above the annual limit value, were observed at traffic stations, with the exception of a few urban background stations in Turkey (EEA, 2019a). Of the 1 004 traffic stations considered, 284 (28 %) reported concentrations above the annual limit value (Fig. 1). The situation for background concentrations is quite different (Fig. 2): of the 1 808 stations shown, only 44 (2.4 %) recorded concentrations above the annual limit value. These are mainly located in big cities such as Istanbul, Ankara, Milan, London, Madrid, Rome and Barcelona, but also in smaller cities such as Ordu, Konya and Cremona.

These results are consistent with observations that indicate that road transport is the main emitting source of nitrogen oxides (NOx) (EEA, 2019b), of which NO2 is one, in the 33 European Environment Agency (EEA) member countries, that is, the 28 EU Member States plus Iceland, Liechtenstein, Norway, Switzerland and Turkey (EEA-33), and that reductions in emissions from road transport were lower than originally anticipated over the last two decades. This is because, among other things, growth in the use of diesel vehicles has been higher than expected and 'real-world' emissions of NO— particularly from diesel passenger cars and vans — generally exceed the permitted European emission (Euro) standards (EEA, 2018b).

For PM10, the situation is different. Of all reporting stations, 22 % show values above the daily limit value of 50 µg/m3 (EEA, 2019b). Fig. 3 illustrates that, of a total of 750 traffic stations, 142 (19 %) show concentrations above the daily limit value. Fig. 4 shows that 447 (26 %) out of a total of 1 751 background stations exceeded the daily limit value. Nevertheless, in certain countries these exceedances are recorded at only traffic stations, i.e. in Germany, Iceland, Latvia, Malta, Portugal and Sweden. On the contrary, the exceedances in Bosnia and Herzegovina and Serbia were measured at only background stations. 

As highlighted in the EEA's Air quality in Europe — 2019 report (2019a), other major sectors are also responsible for primary PM10 emissions. These include the 'commercial, institutional and households', 'industrial processes and product use' and 'agriculture' sectors (EEA, 2019b), which also contribute to exceedances recorded at background stations.

Finally, for PM2.5, exceedances of the annual limit value of 25 µg/m3 also seem to be caused by sources other than traffic. In 2017, PM2.5 concentrations were higher than the annual limit value at 7 % of all reporting stations (EEA, 2019a). Fig. 5 shows that, of 340 traffic stations, only 23 (around 7 %) reported concentrations above the annual limit value. Similarly, Fig. 6 shows that, of 901 background stations, 69 (8 %) reported values above the annual limit value. Again, in the EEA-33, the 'commercial, institutional and households' sector was the main emitter of primary PM2.5 in 2017, followed by 'industrial processes and product use' and 'road transport'.

Supporting information

Indicator definition

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

The indicator makes use of official data submitted to the EEA’s Air Quality e-Reporting database.

Units

This indicator reports pollutant concentrations at traffic and background stations in micrograms per cubic metre (µg/m3).


 

Policy context and targets

Context description

This indicator provides information relevant to current European air quality legislation related to the setting of national emissions targets, the reduction of transport-related emissions (discussed in detail in TERM003 (EEA, 2018b)) and the protection of human health from harmful air pollutant levels (EU, 2008). It is related to the World Health Organization's (WHO's) Air Quality Guidelines (WHO, 2000, 2006) for protecting public health.

Targets

EU ambient air quality limit values set by Directive 2008/50/EC for the protection of human health

  • A limit value for PM2.5 of 25 µg/m3 as an annual average; in force since 1 January 2015.
  • A limit value for PM10 of 50 µg/m3 as a daily average, not to be exceeded more than 35 times in a calendar year; in force since 1 January 2005.
  • An additional limit value for PM10 of 40 µg/m3 as an annual average; in force since 1 January 2005.
  • A limit value for NO2 of 200 µg/m3 as an hourly average, not to be exceeded more than 18 times in a calendar year; in force since 1 January 2010.
  • An additional limit value for NO2 of 40 µg/m3 as an annual average; in force since 1 January 2010.

WHO Air Quality Guidelines

  • Annual mean of PM2.5: 10 µg/m3.
  • Twenty-four-hour mean of PM2.5 (99th percentile of the annual daily series (3 days per year)): 25 µg/m3.
  • Annual mean of PM10: 20 µg/m3.
  • Twenty-four-hour mean of PM10 (99th percentile of the annual daily series (3 days per year)): 50 µg/m3.
  • Annual mean of NO2: 40 µg/m3.
  • One-hour mean of NO2: 200 µg/m3.

Related policy documents

  • Directive (EU) 2016/2284, reduction of national emissions of certain atmospheric pollutants
    The directive is amending Directive 2003/35/EC (providing for public participation in respect of the drawing up of certain plans and programmes relating to the environment) and repealing Directive 2001/81/EC. It entered into force at the end of 2016 and aims at compliance with the 2012 amended Gothenburg Protocol. In July 2017, the EU ratified the 2012 amendments to the 1999 protocol.
  • 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

Data submitted to the EEA's Air Quality e-Reporting database have been used. The selected stations include station types classified as 'traffic' for the traffic map and 'background' for the background map. Only stations for which at least 75 % of data per calendar year are valid are used. This means that, in the case of daily values, only those stations with more than 274 valid daily values per calendar year (or 275 days in a leap year) are used and, in the case of hourly values, only those stations with more than 6 570 valid hourly values per calendar year (or 6 588 hours in a leap year) are used.

Average yearly data were obtained for PM2.5 and NO2. For PM10, the annual series of daily values is ordered and percentile 90.41 (P90.41) selected. P90.41 represents, in a complete series, the 36th highest value; if it is above 50 µg/m3, it suggests an exceedance of the PM10 daily limit value. Using P90.41 diminishes the effect of the missing values. 

Methodology for gap filling

No gap filling is applied to the air quality data in the EEA air quality databases.

Methodology references

No methodology references available.

 

Uncertainties

Methodology uncertainty

No uncertainty has been specified.

Data sets uncertainty

Air quality data are officially submitted by national authorities. It is assumed that data have been validated by the national data suppliers. The number of reported stations varies across countries.

Station characteristics and representativeness are often insufficiently documented. Locally (i.e. at the station level), the indicator is subject to year-on-year variations due to meteorological variability.

Rationale uncertainty

No uncertainty has been specified.

Data sources

Other info

DPSIR: State
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • TERM 004
Frequency of updates
Updates are scheduled once per year
EEA Contact Info info@eea.europa.eu

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Geographic coverage

Temporal coverage

Dates

Topics

Tags

Filed under: pm10, transport, air pollution
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