Exceedances of air quality objectives due to traffic

Indicator Assessment
Prod-ID: IND-106-en
Also known as: TERM 004
Created 29 Nov 2017 Published 07 Dec 2017 Last modified 07 Dec 2017
5 min read
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The annual EU limit value for nitrogen dioxide (NO 2 ) — one of the main air quality pollutants of concern, which is typically associated with vehicle emissions — was widely exceeded across Europe in 2015. Some  89 % o f these exceedances occurred at roadside monitoring locations.  The EU limit values for the two categories of particulate matter ( PM 10  and   PM 2.5 ) were exceeded at fewer locations and at around the same amount of traffic and background stations, in comparison with last year. This indicates the importance of other emission sources  for these pollutants , such as commercial and institutional buildings, household heating, etc.

Key messages

  • The annual EU limit value for nitrogen dioxide (NO2) — one of the main air quality pollutants of concern, which is typically associated with vehicle emissions — was widely exceeded across Europe in 2015. Some 89 % of these exceedances occurred at roadside monitoring locations. 
  • The EU limit values for the two categories of particulate matter (PM10 and PM2.5) were exceeded at fewer locations and at around the same amount of traffic and background stations, in comparison with last year. This indicates the importance of other emission sources for these pollutants, such as commercial and institutional buildings, household heating, etc.

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

Annual mean NO2 concentrations observed at traffic stations, 2015

Note: The figure shows the annual mean concentrations of nitrogen dioxide (NO2) observed at traffic stations in 2015.

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Annual mean NO2 concentrations observed at background stations, 2015

Note: The figure shows the annual mean concentrations of nitrogen dioxide (NO2) observed at background stations in 2015.

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90.4 percentile of daily mean PM10 concentrations observed at traffic stations, 2015

Note: The map shows the 90.4 percentile 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. The red and dark-red dots 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.

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90.4 percentile of daily PM10 concentrations at background stations, 2015

Note: The map shows the 90.4 percentile 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. The red and dark-red dots 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.

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Annual mean PM2.5 concentrations observed at traffic stations, 2015

Note: The figure shows the annual mean concentrations of particulate matter (PM2.5) observed at traffic stations in 2015.

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Annual mean PM2.5 concentrations observed at background stations, 2015

Note: The figure shows the annual mean concentrations of particulate matter (PM2.5) observed at background stations in 2015.

Data source:
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Figures 1 to 6 show the air quality situation in 2015 at monitoring stations across Europe for three main pollutants related to road transport, i.e. NO2, PM10 and PM2.5. For each pollutant, measurements taken at two different locations 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, most of the exceedances (89 %) of the 40 µg/m3 annual limit value, were recorded at traffic stations (Figure 1). Of all the 752 traffic stations considered, 250 (33 %) reported concentrations above the annual limit value. The situation for background concentrations is quite different (Figure 2): of the 1 590 stations shown, only 27 (2 %) recorded concentrations above the annual limit value. These are located in big cities such as Milan, London, Madrid, Rome, Barcelona, Marseille, Turin and Genoa.

These results are consistent with the observations that road transport is the main emitting source of nitrogen oxides (EEA, 2017c), of which NO2 is a component, and that emission reductions from road transport have been lower than originally anticipated over the last two decades. The latter is because, among other things, growth in 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, 2017b).

For PM10, the situation is different. Around one fifth of reporting stations (for both traffic and background stations) show values above the daily limit value of 50 µg/m3. Figure 3 shows, of a total of 633 traffic stations, of which 113 stations (18 %) show concentrations above the daily limit value. Figure 4 shows that 300 (21 %) out of a total of 1 449 background stations exceeded the daily limit value. Nevertheless, traffic is the cause of these exceedances in certain countries; Cyprus, Estonia, Germany, Lithuania, Portugal and Sweden.

As highlighted in EEA (2017c), there are other major sectors responsible for primary PM10 emissions. These include the 'commercial, institutional and households', 'industrial processes and product use' and 'agriculture' sectors, which also influence the exceedances recorded by background stations.

Finally, for PM2.5, exceedances of the annual limit value of 25 µg/m3 seem to be caused by sources other than traffic. Figure 5 shows that out of 256 traffic stations, only 13 (5 %) reported concentrations above the annual limit value. Similarly, figure 6 shows that out of 718 background stations, 54 (8 %) reported values above the annual limit value. Again, the 'commercial, institutional and households' sector is the main emitter of primary PM2.5 (EEA, 2017c), followed by road transport, whose emissions in 2015 decreased by just 5 % compared with 2014 figures (EEA, 2017b).

Indicator specification and metadata

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 increased 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 data base.

Units

The units used in this indicator are pollutant concentrations at traffic and background stations, measured 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 emission targets (EU, 2016), the reduction of transport related emissions (discussed in detail in TERM 003 (EEA, 2017b)) and the protection of human health from harmful air pollutant levels (EU, 2008). It is related to the WHO 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
  • 24-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
  • 24-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
  • 1-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 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. That is, in the case of daily values, those having more than 274 valid daily values per calendar year (or 275 days in a leap year). And in the case of hourly values, this means those stations with more than 6 570 valid hourly values per calendar year (or 6 588 hours in a leap year).

Average yearly data were obtained for PM2.5 and NO2. For PM10, the annual series of the daily values is ordered and the percentile 90.41 (P90.41) selected. This 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 the 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

Generic metadata

Topics:

information.png Tags:
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DPSIR: State
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)

Contacts and ownership

EEA Contact Info

Alberto Gonzalez Ortiz

EEA Management Plan

2017 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