Quality assurance principles

The quality of emission and ambient air quality measurements is based essentially on a range of programmes to whose implementation science, industry and administrative authorities contribute to different degrees. Recognised measuring and testing institutes deserve particular mention in this context, since they fulfil important tasks.

Measurement quality is assured by

• the provision of reference measurement methods,
• the preparation and implementation of tests to verify the suitability of measuring instruments,
• the qualification and accreditation of specialised institutes,
• ring tests among accredited measuring institutes for measurement tasks in the field of emission and ambient air quality monitoring.

The German Federal Environment Agency (Umweltbundesamt – UBA) serves as the national reference laboratory, together with the State Office for Nature, Environment and Consumer Affairs (Landesamt für Natur, Umwelt und Verbraucherschutz) of North-Rhine Westphalia, to set the benchmarks of air quality assessment. In observance of the Directive of the European Parliament and of the Council on ambient air quality and cleaner air for Europe, it ensures the application of standardised methods and criteria by the responsible authorities at the federal state level.

Quality assurance

A number of different methods are applied to assure validity of measurements. In intercomparison tests measurements of an identical sample are taken at the different institutions to allow inter-comparison of the institutes, and accuracy of measurement and capability of the institutions in the network can be determined.

Measurement requires consistent and comparable reference values, thus international and national standards. These standards, which act in measurements of air pollution as something of the International Prototype Metre, are issued by the UBA reference laboratory. All other measurements taken in Germany are traceable to these standards. Traceability is indispensable in quality assurance.

European cooperation

The Federal Environment Agency Reference Laboratory participates in interlaboratory comparisons and harmonisation programmes, which are carried out by the European Reference Laboratory for Air Pollution (ERLAP) of the Institute for Environment and Sustainability at the EC Joint Research Centre in Ispra, Italy.
The reference laboratory is also a member of AQUILA, a network of European reference laboratories. It is a forum for the laboratories responsible for implementation of the directive in their respective countries to exchange information at training courses, in workshops, and at conferences.  

EU-project MACPoll

The Joint Research Project MACPoll (Metrology for Chemical Pollutants in Air) runs under the European Metrology Research Program.
Twelve European Metrology Institutes and two Researchers Excellence Grants are working side by side in research activities related to ambient and indoor air. The overall goal is to improve the traceability and comparability of measurement results in current air monitoring techniques and to set-up the metrological bases for sensor technology used in air quality applications.

The duties and responsibilities of the UBA National EU Reference Laboratory comprise the coordination of quality assurance activities for the measurements of the compounds regulated by EU Directive 2008/50 on ambient air quality and cleaner air for Europe.

The air pollutants addressed are:

• Sulphur dioxide
• Nitrogen oxides
• Carbon monoxide
• Benzene
• Ozone

Main focus areas include:

• Organisation and execution of intercomparison tests and calibration experiments at  national level.
• Participation in international intercomparisons under the responsibility of the Commission (ERLAP).
• Cooperation with all Member State reference laboratories to establish quality policy and quality objectives.
• Development of guidelines and standards of measurement methods for air quality monitoring in the national (VDI, DIN) and international (ISO, CEN) framework.
• Support development and introduction of new techniques and methods.
• Cooperation with WHO Collaborating Centre for Air Quality Management and Air Pollution at UBA.
• Collaboration with Physikalisch-Technische-Bundesanstalt (PTB – national metrology institute providing scientific and technical services) in the field of in metrology in chemistry particularly with regard to air pollution control.

Metrological traceability of ambient air measurements

The reference laboratory supplies the German national standards for comparison measurements to ensure that all measurements made by the  authorities responsible for air quality monitoring (federal states) are based on and traceable to these standards. The objective is to harmonise air quality data within Germany so that data from the entire country is based on a consistent reference standard.

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 requires that national reference laboratories be accredited for application of reference methods according to DIN EN ISO/IEC 17025 standard  “General requirements for the competence of testing and calibration laboratories" when participating in Community interlaboratory tests.

Compliance with the standard was secured when the UBA’s National EU Reference Laboratory introduced a quality management system, which has been reviewed and verified by the German Association for Accreditation (Deutsche Gesellschaft für Akkreditierung).

The quality management system is based on the quality management manual which details the quality assurance strategy, quality policy and the interrelationships of departments within UBA.

The scope of the accreditation in the category of chemical testing comprises the standard methods required by the EU Directive:

1. DIN EN 14211:2005 “Ambient air quality – Measurement method for the determination of the concentration of nitrogen dioxide and nitrogen monoxide by chemiluminescence”
2. DIN EN 14212:2005 “Ambient air quality – Measurement method for the determination of the concentration of sulphur dioxide by UV fluorescence”
3. DIN EN 14626:2005 “Ambient air quality – Measurement method for the determination of the concentration of carbon monoxide by non-dispersive infrared”
4. DIN EN 14625:2005 “Ambient air quality – Measurement method for the determination of the concentration of ozone by UV photometry”
5. DIN EN 14662:2005 “Standard method for the determination of benzene in ambient air – Part 3: Method with automated gas chromatographs”,

applied exclusively for measurement of synthetic test gases, e.g. in interlaboratory comparisons or test gases in cylinders. Monitoring of ambient air quality is the responsibility of the individual federal states.

Accreditation certifies the UBA’s National EU Reference Laboratory for Ambient Air Quality   competence to apply the aforementioned reference methods and grants international recognition.

Within Germany’s metrological network, it is the responsibility of the EU Reference Laboratory to develope, maintain, and disseminate national standards for air quality monitoring activities pursuant to EU regulations and thus ensure the metrological traceability of air quality data.

These measurement standards are realizations of the mole (the SI unit of amount of substance) as primary gas mixtures or primary measurement methods to calibrate the reference instruments.

 Certified reference materials with assigned values traceable to our standards are then used  for instrument calibration in the measurement networks of the air quality monitoring authorities (German federal states).

As part of the national metrology network the EU Reference Laboratory is committed to accuracy in preparation and dissemination of the standards.

To retain its recognition as the ultimate authority in the national chain of traceability, the EU Reference Laboratory is obliged to participate in international comparisons of measurements, so called key comparisons, organised by the Comité Consultatif pour la Quantité de Matière (CCQM), and Consultative Committee for Amount of Substance – Metrology in Chemistry.  Participation results in securing international recognition of metrological standards upon entry of Calibration and Measurement Capability (CMC) in Annex C to the International Bureau of Weights and Measures database (BIPM).

The EU Reference Laboratory has proved successful since 1999 in comparison measurements of the gaseous air pollutants regulated by the air quality directive. Results are available in Annex B of the BIPM database.