Exceedances of air quality limit values due to traffic

Assessment versions

Published (reviewed and quality assured)

• No published assessments

Rationale

Justification for indicator selection

This indicator shows the effect that transport has on air quality, focusing on particulate matter (both PM₁₀ and PM_2.5) and NO₂. The negative impacts of these pollutants on human health are outlined in CSI004 (EEA, 2018a). Road transport is the largest source (or one of the largest sources) of emissions for these selected pollutants. Especially in urban areas, where the majority of the European population lives and works, the contribution of road transport emissions to observed pollutant concentrations is particularly high, leading to increased exposure to those pollutants. It is, therefore, relevant to compare concentrations observed at traffic stations (stations located close to road traffic emission sources, which are often in city centres) with those observed at background stations.

Scientific references

• No rationale references available

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 PM_2.5 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 PM_2.5: 10 µg/m³.
• Twenty-four-hour mean of PM_2.5 (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 PM_2.5 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.

Data specifications

EEA data references

• Air Quality e-Reporting (AQ e-Reporting) provided by European Commission

Data sources in latest figures

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.