BS EN 14625:2024 - Page 3

Ambient air. Standard method for the measurement of the concentration of ozone by ultraviolet photometry. | Status: Current

1 Scope This document specifies a continuous measurement method for the determination of the concentrations of ozone present in ambient air based on the ultraviolet photometric measuring principle. This document describes the performance characteristics and sets the relevant minimum criteria required to select an appropriate ultraviolet photometric analyser by means of type testing. It also includes the evaluation of the suitability of an analyser for use in a specific fixed site in order 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 ozone present in ambient air up to 500 µg/m3. This concentration range represents the certification range for ozone for type testing.

NOTE 1 Other ranges may be used for measurement systems applied at rural locations monitoring ecosystems.

NOTE 2 When this document is used for other purposes than Directive 2008/50/EC, the ranges and uncertainty requirements may not apply.

The method covers the determination of ambient air concentrations of ozone in zones classified as rural areas, urban and urban-background areas. The results are expressed in µg/m3 (at 20 °C and 101,3 kPa).

NOTE 3 500 µg/m3 of O3 corresponds to 250 nmol/mol of O3 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 ozone measurement by ultraviolet photometric analyser and sampling equipment. Clause 8 and Annex E are specifically directed towards test houses and laboratories that perform type testing of ozone analysers. 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 ozone analyser 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 ozone 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 uncertainty of measurement results under practical monitoring conditions.

This document represents an evolution of earlier editions (EN 14625:2005 and EN 14625:2012).

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.