The Ambient Air Quality Directives require the assessment of the ambient air quality in Member States based on common methods and criteria for air quality monitoring and modelling. This comprehensive assessment is required throughout the whole territory of each country. The assessments should be done in a way so that they are representative of other locations. Find out more about spatial representativeness.
When air quality monitoring is being used for air quality assessment, it is extremely important to appropriately site sampling points. This ensures monitoring information can be used to obtain further information on:
- Exposure of the population to air pollutants
- Source apportionment that supports the development of air policy
- Air pollution management in the area
Key provisions
Amongst other key provisions, Directive (EU) 2024/2881:
- Requires that air quality zones be classified according to an assessment regime, which will define which assessment methods are required.
- Establishes a minimum number of sampling points for regulated pollutants, ultrafine particles (UFPs), and for the additional pollutants of Annex VII.
- Establishes the location for these sampling points.
- Allows Member States to subtract the contribution of natural sources under certain conditions before comparing the ambient air pollutant concentrations to the limit values. See the Guidelines and an assessment study performed in 2022 for more information.
- Allows Member States to subtract PM10 attributable to winter-sanding or winter-salting of roads when assessing compliance with air quality limit values provided that reasonable measures have been taken to lower concentrations. See the Guidelines for more information.
Guidance and technical support documents
For the implementation of the Ambient Air Quality Directives, several guidance and technical support documents have been prepared with the extensive support from national experts.
- Technical support document on the use of reference and non-reference methods, and on the quality assurance process to meet relevant data quality objectives for regulated air pollutants
- Technical support document on the use of modelling for various application domains under the Ambient Air Quality Directive
- Support document on setting up common measuring stations for PM2.5 under Directive 2008/50/EC on ambient air quality and cleaner air for Europe
- Guidance report on Preliminary Assessment under EC Air Quality Directives
- Guidance on Assessment under the EU Air Quality Directives
- Decision 2004/279/EC, guidance for implementing the ozone directive
- Guidance on assessment around point sources
Reference air quality measurement methods
For regulated pollutants, a reference measurement method has been prescribed, which can be found in Annex VI of the Ambient Air Quality Directive (EU) 2024/2881. The situation has evolved and the following reference measurement methods have been updated since the adoption:
- Benzene part 1 EN 14662: 2023
- Ozone: EN14625:2024
The standards can be obtained through the national standardisation organisation here.
Non-reference measurement methods can also be used provided they respect provisions for equivalence set out in the Directives (Annex VI). A Commission Working Group on Equivalence has prepared a document describing principles and methodologies to be used to demonstrate the equivalence of alternative (non-reference) measurement methods to the reference methods described by the EN Standard methods:
The corresponding tool to facilitate the use of the guidance (in particular for checking the equivalence of non-reference methods for PM-monitoring) has been developed. The updated version is now available:
The technical support document on the use of reference and non-reference methods provides information on measurement related matters for all regulated pollutants in the AAQD. This includes description of measurement methods, data quality objectives, Quality Assurance and Quality Control (QA/QC) for fixed and indicative measurements and considers objective estimation. The document also gives advice on best practices and references other sources of information where applicable.
Air quality modelling
Air quality modelling applications are considered to provide supplemental information to air quality monitoring by enabling point data (e.g. from fixed measurements) to be interpreted in terms of the geographical distribution of concentrations.
In addition to air quality assessments, modelling applications can provide more comprehensive information on public exposure, support the identification of sources, inform air quality plans and roadmaps, and perform future projections based on different measures scenarios.
The Technical support document on the use of modelling for various application domains provides support for the use of modelling systems under various application domains mentioned by the AAQD.
A Forum for AIR quality Modelling (FAIRMODE) of modellers and users has been established. It aims in bringing together air quality modelers and users in order to promote and support the harmonized use of models by EU Member States, with emphasis on model application under the European Air Quality Directives. The FAIRMODE webpage contains links to its current activities.
Objective estimation of air quality
The Ambient Air Quality Directives also allow for objective estimation as an air quality assessment method for air quality zones with very good air quality. By identifying local pollution sources and information on regional air quality, an estimation of the concentration of a regulated pollutant is made.
Ensuring the quality of assessment information either generated through monitoring, modelling, or objective estimation is one of the paramount provisions of the Directive. Data quality objectives are prescribed with the aim of defining maximum allowed uncertainty and data coverage (proportion of the calendar year for which there is valid data).
Member States are responsible for ensuring appropriate quality assurance of the assessment as well as the appropriate quality control of the information provided to the public and through the assessment reports. The Commission has set-up a community-wide process, managed by the Joint Research Centre (JRC).
AQUILA is a network of national reference laboratories that provides expert advice to the Commission. In its website you may find more information on its objectives, support documents, and quality assurance procedures and programmes. It has prepared an extensive document that summarises the roles and responsibilities of the national reference laboratories and of the network itself, describes the quality assurance procedures and makes EU-wide comparisons.
The European Environment Agency (EEA) together with EIONET and its Topic Centre also supports quality assurance of the data and reporting of air quality assessment information.