UNE-EN 14625:2025

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 specified in Annex I of Directive 2008/50/EC [1] 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 ¼g/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 ¼g/m3 (at 20 °C and 101,3 kPa).

NOTE 3 500 ¼g/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 uncertainty of the measurement results of 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.

The present document represents an evolution of earlier editions (EN 14625:2005 and EN 14625:2012). It is recommended that when equipment is procured it complies fully with the present document.

NOTE 4 Type testing performed prior to the publication of this document for the purpose of demonstrating equivalence are still valid.

NOTE 5 Analysers type tested prior to the publication of this document remain valid for use for regulated monitoring purposes.