3.2.1.1 Monitoring requirements
The EU Air Quality Directive 2008/50/EC requires that as a minimum one rural background station is installed every 100,000 km2 for measuring PM2.5 in order to get data on the total mass concentration and the chemical speciation (EC, 2008). This minimum is larger than the total surface area of several Member States. The Directive further states that Member States shall set up at least one measuring station or may by agreement with adjoining Member State set up together one or several common measuring stations. It is recommended to identify types of rural background areas relating to climatic and topographic conditions that can be considered representative for large parts of the Member State’s territory (EC, 2011). Existing stations or potential new sites can then be selected in such a way that a maximum percentage of the territory is covered. Subsequently, agreement with neighboring Member States on appropriate common stations should be sought.
3.2.1.2 Reference measurement methods
For each regulated pollutant, a reference measurement method is prescribed. At the time of the adoption of directives, standardized methods had not been developed for all pollutants. The situation has since developed, and the updated list of reference measurement method is shown in Table 0.1.
Table 0.1: Standard methods for the measurement of air pollutants
Pollutant Reference Title
SO2 EN 14212:2012 Ambient air - Standard method for the measurement of the concentration of sulphur dioxide by ultraviolet fluorescence
NO2 and NO EN 14211:2012 Ambient air - Standard method for the measurement of the concentration of nitrogen dioxide and nitrogen monoxide by chemiluminescence
Pb, Cd, As and Ni EN 14902:2005 Ambient air quality - Standard method for the measurement of Pb, Cd, As and Ni in the PM10 fraction of suspended particulate matter
PM2.5/PM10 EN 12341:2014 Ambient air - Standard gravimetric measurement method for the determination of the PM10 or PM2.5 mass concentration of suspended particulate matter
Benzene EN 14662:2005 Ambient air quality - Standard method for measurement of benzene concentrations
CO EN 14626:2012 Ambient air - Standard method for the measurement of the concentration of carbon monoxide by non-dispersive infrared spectroscopy
OC/EC EN 16909:2017 (WI=00264164)
Ambient air - Measurement of elemental carbon (EC) and organic carbon (OC) collected on filters
Source: https://www.cen.eu/cenorm/members/members/index.asp accessed on 01/07/2020
3.2.1.3 Equivalence
Non-reference measurement methods can also be used provided they respect provisions for equivalence set out in the Directives (see for example Directive 2008/50/EC, Annex VI). A Commission Working Group on Equivalence has prepared a document describing principles and methodologies to be used for the demonstration of the equivalence of alternative (non-reference) measurement methods to the reference methods described by the EN2 Standard methods. The air quality committee established under Directive 2008/50/EC endorsed the new guidance for the implementation of the Directive 2008/50/EC (EC, 2008). 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 in MS-Excel3.
2 Each European Standard is identified by a unique reference code which contains the letters 'EN'. A European Standard is a standard that has been adopted by one of the three recognized European Standardization Organizations (ESOs): CEN, CENELEC or ETSI. It is produced by all interested parties through a transparent, open and consensus-based process.
3 See: https://ec.europa.eu/environment/air/quality/legislation/pdf/Equivalence%20Tool%20v10.xlsm
3.2.1.4 Modelling
In the AAQ Directive, modelling is considered to provide supplemental information to air quality monitoring and is to be used where monitoring is not mandatory. Modelling is becoming a principal assessment tool that is validated by monitoring. It provides much more comprehensive information as regards public exposure, identification of sources, and future projections of air quality based on different policy measures scenarios.
Use of modelling has been also developed under specific initiatives such as the ‘Harmonization within atmospheric dispersion modelling for regulatory purposes’ project (HARMO). Under the 6th Research Framework programme an Air4EU project (https://www.air4eu.nl/) has been concluded which facilitates combined use of monitoring and modelling for the air quality assessment through the developed guidance and IT tools.
3.2.1.5 Objective estimation
Objective estimation is reserved for the air quality zones with very good air quality and no large conurbations.
It is usually combined with modelling. By identification of local pollution sources and information of regional air quality an estimation of concentration of a regulated pollutant is made.
3.2.1.6 Ensuring quality of assessment information
Ensuring the quality of assessment information either generated through monitoring, modelling or objective estimation is one of the paramount provisions of the directives. Data quality objectives are prescribed which define maximum allowed uncertainty, time coverage and data coverage. While Member States are responsible for appropriate quality assurance of the assessment as well as for appropriate quality control of the information provided to the public and through assessment reports, the Commission set-up a community-wide process managed by the Joint Research Centre (JRC). JRC organizes comparison exercises for the national reference laboratories and manages the AQUILA4 (European Network of National Air Quality Reference Laboratories) network which monitors the implementation of assessments by monitoring, serves as exchange forum, and provides expert advice to the Commission.
3.2.2 Reporting
Member States have to send validated monitoring data to the Commission once a year, and to continuously transmit up to date (near real-time) air quality data. Reporting obligations include monitoring data and information about sampling points and assessment methods, exceedance situations and alerts, about contributions from natural sources, road sanding and salting, about air quality plans and measures.
Since 2013, the requirements for the reciprocal exchange of information and reporting on ambient air quality are governed by Implementing Decision 2011/850/EU5. Accordingly, data is by now submitted via e-reporting through the Reporting Obligation Database (Central Data Repository) of the European Environment Information and Observation Network (EIONET), hosted by the European Environment Agency (EEA).
4 See: https://ec.europa.eu/jrc/en/aquila
5 Implementing Decision 2011/850/EU laying down rules as regards the reciprocal exchange of information and reporting on ambient air quality applies since 1 January 2014 (i.e. for data observed in 2013).
In this manner, all Member States report information on zones and agglomerations (Dataflow B), on assessment regimes (Dataflow C), on assessment methods (Dataflow D), on primary validated assessment data (Dataflow E1a), and on the attainment of environmental objectives (Dataflow G)6. By 2019, 26 Member States reported primary up-to-date assessment data (Dataflow E2a). For 2017, 12 Member States reported also modelled data (Dataflow E1b).
Based on the data reported by Member States, the EEA provides online access to all reported air quality data, statistics, and maps, and publishes an annual air quality report summarizing key findings. It also provides access to this data via online information services such as the European Air Quality Index.
This information has been increasingly made available and accessed by a wider public. In addition to the official air quality data and information that is made available to a wider public at EU-level and by national authorities, the availability and popularity of so-called low‑cost air quality sensors has increased over the past few years.
The current generation of low-cost sensors, however, tends to deliver measurements of lower data quality than monitoring carried out in accordance with the AAQ Directives (JRC, 2017). Recently, citizen science monitoring campaigns have successfully used low-cost sensors to increase public awareness and public engagement on air quality issues (https://curieuzeneuzen.be/).
3.2.3 Enforcement
The AAQD requires Member States to take appropriate measures to ensure compliance with the limit and target values within a specified deadline and/or to maintain compliance once the limit and target values have been met. Therefore, air quality plans are required for polluted zones and agglomerations where air quality standards are exceeded and/or for zones and agglomerations where there is a risk of exceedances. These plans must aim to reduce concentrations of air pollutants to below the legislative limit and target values specified in the Directives in the shortest possible time. Details of the plans must be reported by Member States to the European Commission via the EEA. When and where concentrations of pollutants in ambient air exceed the relevant target values or limit values, the AAQ Directives require Member States to develop air quality plans and/or take appropriate measures (depending on the pollutant), so that the related target values or limit values are achieved in the respective zones and agglomerations, and that exceedance periods are kept as short as possible.