BS EN 14211:2024 - Page 2

Ambient air. Standard method for the measurement of the concentration of nitrogen dioxide and nitrogen monoxide by chemiluminescence. | Status: Current

1 Scope This document specifies a continuous measurement method for the determination of the concentrations of nitrogen dioxide and nitrogen monoxide present in ambient air based on the chemiluminescence measuring principle. This document describes the performance characteristics and sets the relevant minimum criteria required to select an appropriate chemiluminescence analyser by means of type testing. It also includes the evaluation of the suitability of an analyser for use in a specific fixed site so as to meet the data quality requirements (see Annex I of Directive 2008/50/EC[1] for additional information) and requirements during sampling, calibration and quality assurance for use. The method is applicable to the determination of the concentration of nitrogen dioxide present in ambient air up to 500 µg/m3. This concentration range represents the certification range for nitrogen dioxide for type testing. The method is applicable to the determination of the concentration of nitrogen monoxide present in ambient air up to 1 200 µg/m3. This concentration range represents the certification range for nitrogen monoxide for the type testing.

NOTE 1 It is possible to use other ranges depending on the levels present in ambient air.

NOTE 2 Exemplar uncertainty budget calculations are given in Annexes F to H referring to Directive 2008/50/EC[1]. In the event that the Limit Values are updated in future iterations of Directive 2008/50/EC[1], the user can use these new values to calculate measurement uncertainties.

The method covers the determination of ambient air concentrations of nitrogen dioxide and nitrogen monoxide in zones classified as rural areas, urban-background areas, traffic-orientated locations and locations influenced by industrial sources. The results are expressed in µg/m3 (at 20 °C and 101,3 kPa).

NOTE 3 500 µg/m3 of nitrogen dioxide corresponds to 261 nmol/mol of nitrogen dioxide at 20 °C and 101,3 kPa. 1 200 µg/m3 of nitrogen monoxide corresponds to 962 nmol/mol of nitrogen monoxide at 20 °C and 101,3 kPa.

This document contains information for different groups of users. Clause 5 to Clause 7 and Annex B and Annex C contain general information about the principles of NOx measurement by chemiluminescence analyser and sampling equipment. Clause 8, Annex E is specifically directed towards test houses and laboratories that perform type testing of NOxanalysers. These sections contain information about:

• — type testing conditions, test procedures and test requirements;
• — analyser performance requirements;
• — evaluation of the type testing results;
• — evaluation of the associated uncertainty of the measurement performed by the NOxanalyser based on the type testing results.

Clause 9 to Clause 11 and Annex F and Annex G are directed towards monitoring networks performing the practical measurements of NOx in ambient air. These sections contain information about:

• — initial installation of the analyser in the monitoring network and acceptance testing;
• — ongoing quality assurance/quality control;
• — calculation and reporting of measurement results;
• — evaluation of the associated uncertainty of the measurements under practical monitoring conditions.

This document represents an evolution of earlier editions (EN 14211:2005 and EN 14211:2012).

NOTE 4 Analysers type tested prior to the publication of this document can still be used for regulated monitoring purposes. As newer versions of analysers tested under this document become available, discontinue the use of older reference analysers.